Cell growth, differentiation and development; Cytoskeleton and cell motility; Genomics and proteomics; Molecular and Cellular Biology; Molecular Basis of Disease; Gene Expression; Signal Transduction; Cell Cycle
I am a cell biologist and bioengineer, and my primary research focuses on the rapidly growing area of cell mechanics and mechanotransduction: the role that mechanical forces play in regulating cellular function from healthy to diseased phenotypes. (1) Cardiovascular Biology, Mechanics and Disease: Funding source: American Heart Association (7/1/2018–6/30/2021; PI) Cardiovascular disease (CVD) is the main cause of death globally. Arterial stiffness is associated with many CVD. The molecular mechanisms governing arterial stiffening and the phenotypic changes in vascular smooth muscle cells (VSMCs) associated with the stiffening process are key areas in cardiovascular biology, mechanics and disease. Evidence suggests that arterial stiffening can drive aberrant migration and proliferation of VSMCs within the vessel wall. Yet, the underlying mechanisms regulating vascular stiffening and the molecular changes within VSMCs associated with the stiffening process remain unclear. While medications reduce hypertension, none specifically target pathways directly related to arterial stiffness. The overall goal of work in my lab is to address this gap in our understanding by investigating how changes in arterial stiffness affect VSMC function and fundamentally contribute to the progression of CVD. This study also addresses an important concept in vascular tissue remodeling (the interaction between extracellular matrix stiffness and VSMC behavior). Methodologically, my lab use a novel approach to dissect the molecular mechanism in VSMCs: My lab combines methods for manipulating and measuring tissue and cell stiffness using atomic force microscopy and traction force microscopy for simultaneously modulating substrate stiffness and measuring contraction force by culturing cells on a compliant substrate that mimics in vivo mechanical environments of the VSMCs. (2) Smooth Muscle Cell (and Cancer Cell) Heterogeneity: Highly heterogeneous responses of VSMCs to arterial stiffness or CVD make it difficult to dissect underlying molecular mechanisms. To overcome this, my lab integrates Mechanobiology, Vascular Cell Biology, and Machine Learning to manipulate stiffness and assess responses with unique precision. Machine learning is used to deconvolve inter- and intra-cellular heterogeneity and identify specific subcellular traits that correlate with stiffness and VSMC behavior. My lab also applies Machine Learning approaches to identify specific breast cancer cell behaviors that respond to different stiffness conditions. (3) Optogenetics and Biophotonics in Stem Cell Biology: Funding source: National Science Foundation (8/1/2017–7/31/2020; co-PI) Major breakthroughs in the field of genomics, embryonic stem cell biology, optogenetics and biophotonics are enabling the control and monitoring of biological processes through light. Additional research in my laboratory focuses on developing a nanophotonic platform able to activate/inactivate gene expression and, thus, control stem cell differentiation in neuronal cells, by means of light-controlled protein-protein interactions. More specifically, the light-controlled molecular toggle-switch based on Plant Phytochrome B and transcription factor Pif6 will be utilized to control the nuclear fibroblast growth factor receptor-1, which is a master regulator of stem cell differentiation. Open Positions: The Bae lab is currently accepting graduate students through the Pathology Masters program (or other programs) as well as motivated undergraduates. For Graduate Students: I am looking for one or two graduate (MS) students who understand my research interests, have read my previous publications, and have their own (crazy!!!) ideas as to where my research efforts should be directed. All graduate students are required to complete and submit internationally recognized Journal article(s) before graduation from my lab. A Masters thesis should generate at least one first author publication. For Undergraduate Students: I encourage all UB undergraduates (with GPA 3.0 or higher) to get "hands on" experimental training in the sciences. An undergraduate research project tends to be part of a larger whole, but I make sure to include credit for students work in presentations and publications.
Eukaryotic Pathogenesis; Microbial Pathogenesis; Microbiology; Molecular and Cellular Biology
Human African trypanosomiasis (commonly called Sleeping Sickness) is one of the global great neglected diseases, causing ~10,000 cases annually according to most recent estimates (2009). The related veterinary disease of livestock (Nagana) also has significant impact on human economic well being throughout sub-Saharan Africa wherever the insect vector (tsetse flies) are found. Both diseases are caused parasitic protozoa called trypanosomes (Trypanosoma brucei ssp.) Because trypanosomes are eukaryotic cells, organized similarly to every cell in our bodies, treatment of infection is not unlike cancer treatment in that chemotherapy against the parasite has harsh consequences for the patient. However, infection is invariably fatal without intervention, consequently new more specific drugs are desperately needed. In addition, because trypanosomes are an anciently divergent evolutionary lineage, they provide a unique model system for studying basic eukaryotic biology. My laboratory focuses on the cell biology of these protozoa, specifically on intracellular trafficking of lysosomal and cell surface proteins as key aspects of the host:parasite relationship. The trypanosome lifecycle alternates between the mammalian bloodstream and the tsetse midgut, and each stage has a unique protein surface coat that forms the first line of contact with the host. These coat proteins are anchored in membranes by glycosylphosphatidylinositol (GPI) anchors and are essential for survival in each stage. Consequently, correct protein targeting to the cell surface is critical to the success of the parasite. Also, endocytic and lysosomal functions are greatly up-regulated in the pathogenic bloodstream stage for both nutritional and defensive purposes. Using classic and current cell biological and biochemical approaches we work on four distinct areas: 1) GPI-dependent targeting of surface coat proteins; 2) machinery of secretory trafficking; 3) stage-specific lysosomal biogenesis and proteomics; and 4) role of sphingolipids in secretory transport. Our ultimate goal is to define aspects of trypanosomal secretory processes that may provide novel avenues to chemotherapeutic intervention.
Addictions; Drug abuse; Behavioral pharmacology; Gene therapy; Molecular and Cellular Biology; Neurobiology; Gene Expression; Neuropharmacology
My laboratory seeks to understand the neurobiology of motivation and how these systems can be "highjacked" by abused substances. Substance abuse and addiction are wide-spread problems that have an enormous economic and emotional toll. Reports indicate that it costs the US upwards to $600 billion a year to deal with the health and criminal consequences and loss of productivity from substance abuse. Despite this, there are few effective treatments to combat this illness. The brain has natural systems responsible for motivating an organism to participate in behaviors that are necessary for survival, such as eating, exercise and reproduction. These same brain regions are highly sensitive to drugs of abuse, including cocaine, heroin and marijuana. My laboratory seeks to understand how these brain regions are affected by exposure to abused drugs, and in particular how the motivation to take drugs is altered by various molecular mediators in the neurons on these regions. The two basic questions we are interested in are 1) how projections from the cortex to the striatum influence drug seeking behaviors, and 2) how neurotransmitter receptors, particularly dopamine and cannbinoid receptors in these regions influence drug seeking. Our technical approaches include a number of basic behavioral models including measurements of locomotor activity, catalepsy, conditioned place preference and drug self-administration. In order to probe the circuitry of these brain regions, we use a number of advanced molecular techniques to activate and inactivate neuronal populations including optogenetics and artificial receptors. We probe the molecular pathways within the neurons by over expressing genes or knocking down expression using RNA interference. Gene delivery is accomplished using recombinant adeno-associated virus (rAAV) and several projects in the laboratory focus on improving this approach and exploring potential gene therapy applications for these vectors. The ultimate goal is to understand the basic neurobiology and molecular biology of addiction in order to develop more effective treatments for addiction.
Molecular and Cellular Biology; RNA; Virology
My research is dedicated to the folding of biological macromolecules such as ribonucleic acids and proteins into higher-order structures and to the role their conformation plays in the way they exert their function within the cell. In particular, my research group studies RNA structural switches involved in the replication of RNA viruses and subviral RNA pathogens. We also study RNA and protein structures that contribute to the regulation of gene expression in other microbial systems through specific RNA-RNA and RNA-protein interactions. Plus-strand RNA viruses are responsible for many diseases in humans, animals and plants. Our efforts are focused on an early step in the viral life cycle within the host cell, the recruitment of the viral RNA genome into a replication complex with viral and cellular proteins. We use yeast as a model host to express two RNA replicons, turnip crinkle virus associated with satellite RNA, by itself or in the presence of viral replication proteins, and potato spindle tuber viroid RNA. Satellites and viroids are subviral RNAs that do not encode their own proteins; they rely entirely on factors provided by the associated helper virus or the host cell. The smaller size and simpler organization of their genome makes them convenient model systems to investigate the role of RNA structure in recognition by viral and host proteins, structural changes involved in these interactions, molecular evolution and intracellular transport. Our goal is to develop a fully controlled replication system where every component is tractable and tunable using tools from genetics, biochemistry, cellular and molecular biology. With this system, we will be able to screen for RNA replication inhibitors and develop RNA vectors with novel functions. I enjoy teaching and mentoring students from a variety of disciplines in the laboratory as well as in the classroom. I believe that meaningful faculty/student interaction is mutually beneficial: it helps students grow into well-rounded citizen-scientists, researchers or health care professionals, and it helps me become a better educator. In my research group, I deeply value and strive to foster diversity. I believe a diverse team creates a more energizing and successful research environment--one where everyone learns from one another and the range of backgrounds and perspectives adds up to a rich learning environment that is much more than the sum of its parts. I am the course director for, and teach in Microbiology for Allied Health Professionals. On the graduate level, I direct the master’s program and teach in the core course of virology.
Apoptosis and cell death; Bioinformatics; Molecular Basis of Disease; Molecular and Cellular Biology; Molecular genetics; Neurobiology; Regulation of metabolism
My laboratory studies the cell-autonomous and non-cell-autonomous mechanisms of axon degeneration, a process akin to programmed cell death. In other words, we are attempting to elucidate what causes axon breakdown from within neurons and which external (glial) events trigger axon loss. Degeneration of axons is a hallmark in many neurodegenerative conditions, including those associated with abnormal glia. We have great hope that understanding why and how axons degenerate may lead to more efficient neuroprotective therapies tailored specifically to support axons and their surrounding glia. Axons are the longest cellular projections of neurons relaying electrical and biochemical signals in nerves and white-matter tracts of the nervous system. As such, they are critical for neuronal wiring and transport of neuronal maintenance signals. Because of their incredible length and energetic demand (human motor neurons can be one meter long), however, axons are very vulnerable and at continuous risk of damage. Axons do not exist in isolation but are inextricably and intimately associated with their enwrapping glia (Schwann cells and oligodendrocytes) to form a unique axon-glia unit. The most relevant neurological symptoms in a number of debilitating neurodegenerative conditions are due to compromised axon integrity. Thus, neuroprotective therapies promoting axon stability have great potential for more effective treatment. Recent studies indicate that axonal degeneration, at least in experimental settings, is an active and highly regulated process akin to programmed cell death (‘axonal auto-destruction’). Moreover, it is increasingly realized that axonal maintenance relies not only on neuron-derived provisions but also on trophic support from their enwrapping glia. The mechanism for this non-cell-autonomous support function remains unknown, but emerging evidence indicates that it is distinct from the glial role in insulating axons with myelin. We are pursuing the intriguing question of whether abolished support by aberrant delivery of metabolites and other trophic factors from glia into axons is mechanistically linked to the induction of axonal auto-destruction. This concept is supported by our recent finding that metabolic dysregulation exclusively in Schwann cells is sufficient to trigger axon breakdown.
Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular and Cellular Biology; Neurobiology; Pathophysiology; Gene Expression; Signal Transduction
Neuronal firing patterns are highly diverse because neurons regulate a wide variety of different behaviors and physiological functions including cognition and memory. Whether a neuron exhibits regular spiking, burst firing, adaptation or high frequency firing will largely be determined by which specific ion channel genes a neuron chooses to express. I am interested in a class of potassium channels that are sensitive to intracellular sodium. There are two members in this family, known as Slack and Slick, and both channel subunits are expressed in many different types of neurons. I am particularly interested in how these channels contribute to the firing patterns of pain-sensing neurons and neurons of the cerebral cortex. Understanding when, where and how these channels are working should provide important information on sensory and cortical processing and will provide insights on nociception, psychiatric disorders such as schizophrenia and bipolar disorder and neurological diseases such as epilepsy.
Bioinformatics; Genomics and proteomics; Molecular and Cellular Biology; Molecular genetics; Gene Expression; Transcription and Translation
Instructions controlling cellular functions are contained within DNA that is wrapped and packaged around proteins into chromatin. Chromatin can be modified in response to the environment and these modifications can be passed onto their daughter cells. These modifications act as a cellular memory and are known as epigenetic modifications. Changes in epigenetic modifications are essential players in many disease pathways including: cancer, diabetes, obesity, and autism. Dr. Buck’s research is focused on uncovering how epigenetic changes redirect regulatory proteins and how regulatory proteins read epigenetic modifications. Dr. Buck’s laboratory uses multiple model systems to uncover fundamental biological principles which are subsequently translated to the study of human disease. Epigenomics and Cancer Epigenetic alterations have been associated with cancer-specific expression differences in development of human tumors. The ability to recognize and detect the progression of epigenetic events occurring during tumorigenesis is critical to developing strategies for therapeutic intervention. Key epigenetic alterations, leading to silencing or activation, are associated with changes in nucleosome occupancy. We use chromatin assays (FAIRE-seq, ATAC-seq, MNase-seq, and ChIP-seq) to examine cancer epigenomes from patient samples and cell line models. Transcription factor binding specificity to chromatin. To understand normal developmental processes and disease manifestation and progression we must understand the mechanisms regulating the essential first step of gene activation, transcription factor binding at regulatory regions. Using the developmental transcription factor TP63 we have begun to uncover the rules dictating p63 binding to chromatin. Our findings demonstrated that p63 functions has a pioneer transcription factor that can target it bindings site in closed inaccessible genomic locations. Current in vitro and in vivo studies are beginning to define the how nucleosome position and histone modifications regulate p63 binding. Microbiota in human health Our bodies are populated by a diverse and complex population of thousands of microbes, mostly bacteria, but also viruses, fungi and archaea, termed the human microbiota. This co-inhabiting microbial ecosystem has been associated with various human disease including colon cancer, diabetes, periodontal disease, and others. To understand how the microbiota is affecting human health we are participating in a large epidemiological study examining human oral microbiota samples. We have developed robust and reproducible high-throughput approaches to examine thousands of samples and we are currently defining causual relationships between the microbiota and human health.
Molecular and Cellular Biology; Neurobiology; Neuropharmacology
The goal of my research is the elucidation of the role of brainstem systems in motivated behaviors. My current focus is the function of neuropeptide systems, specifically urotensin II (UII). Ultimately I would like to exploit this system to better treat people with neuropsychiatric disorders. Currently my lab is pursuing the following: 1) Determine the role of UIIR activation and the UIIR expressing neurons in reward-related behaviors:. Our results support the need for further investigation of the UII-system as a therapeutic target for treating drug abuse disorders. In addition, we are investigating the i) bias-signaling properties of the endogenous UIIR ligands, and ii) the impact of UIIR single-nucleotide polymorphisms on receptor signaling. 2) Establish the contribution of cholinergic PPT to Parkinsonism-related behaviors: We designed a toxin that selectively targets UIIR expressing neurons (cholinergic PPT). In rats the toxin-mediated lesion mimics Progressive Supranuclear Palsy (the most common atypical parkinsonism) on multiple fronts: selective ablation of cholinergic PPT neurons, impaired motor function, and deficits in acoustic startle reaction (MacLaren et al, 2014a; MacLaren et al, 2014b). Similarly, the collection of deficits found after non-selective manipulations of the PPT overlap with that of Parkinson’s Disease [e.g. reduced prepulse inhibition, impaired attention, cognitive deficits, sleep disturbances]. Traditional dopamine-depletion models do not produce similar sensorimotor and cognitive deficits. Therefore, PPT lesions as an adjunct or stand alone preclinical models of Parkinsonism may be useful in identifying non-dopaminergic pharmacotherapeutics. We are pursuing further studies utilizing our selective cholinergic depletion and a viral-mediated tauopathy method with support from the CurePSP Foundation.
Allergy and Immunology; Medical Microbiology; Infectious Disease; Microbiology; Genomics and proteomics; Immunology; Microbial Pathogenesis; Molecular and Cellular Biology; Molecular Basis of Disease; Molecular genetics; Gene Expression; Signal Transduction; Protein Function and Structure; Bacterial Pathogenesis
Research efforts in my laboratory are focused in the fields of immunology and bacterial pathogenesis, two diverse fields of biomedical research for which I have two separate research groups. Projects in both fields are performed by undergraduates, doctoral and master’s degree students, postdoctoral fellows and senior research associates. One major focus of my laboratory is studying the regulation of mucosal immune responses. We investigate the cellular and molecular events by which Type II heat-labile enterotoxins (HLTs), produced by certain strains of Escherichia coli, modulate immune responses. We have demonstrated that LT-Ilia, LT-IIb and LT-IIc, when co-administered with an antigen, have the capacity to enhance antibody and cellular immune responses to that antigen. Using a variety of immunological and cellular technologies, including flow cytometry, fluorescence resonance energy transfer (FRET) detection, cytokine multiplex analysis, mutagenesis, quantitative Reverse Transcription PCR (qRT-PCR), RNA-sequencing (RNA-Seq) and a variety of transgenic mice, we are investigating the mechanisms by which these immunomodulators productively interact with various immunocompetent cells (T cells, B cells, dendritic cells, macrophages) to induce or suppress cytokine production, costimulatory ligand expression and cellular proliferation. A practical outgrowth of these experiments is the potential to engineer novel recombinant vaccines by genetically fusing antigens from different pathogens to the enterotoxins. Recent experiments have shown that these HLT are lethal for triple-negative breast cancer cells, which has opened a new area of oncological research for the lab. A second focus of my laboratory is to investigate the molecular mechanisms by which adherent-invasive Escherichia coli (AIEC) induce, exacerbate or prolong the symptoms of inflammatory bowel disease (IBD) and Crohn’s disease, two acute and chronic inflammatory diseases of the human gut. In vitro, AIEC strains invade into the cytoplasm of several epithelial cell lines. Using recombinant screening methods and RNA-Seq technologies, we are identifying the genes of AIEC that are required to attach and to invade gut cells.
Autoimmunity; Bioinformatics; Genomics and proteomics; Immunology; Infectious Disease; Molecular and Cellular Biology; Molecular genetics; Neurobiology
My primary research is in the field of biomedical ontology development. An ontology is a controlled, structured vocabulary intended to represent knowledge within a particular domain. Terms in an ontology have logical relationships to each other and to terms in other ontologies, to allow for reasoning and inference across the ontology. Biomedical ontologies allow annotation and integration of scientific data within particular fields of science and medicine, and their careful curation and logical structure facilitate data analysis. My work in biomedical ontology is strongly informed by my earlier experience in laboratory research in immunology, genetics, molecular biology and virology. My research group works on ontologies for both basic and clinical applications, in collaboration with researchers both at UB and other institutions. I led efforts to revise and extend the Cell Ontology, which is intended to represent in vivo cell types from across biology. We worked extensively to bring it up to community-accepted standards in ontology development, placing particular emphasis on improving the representation of hematopoietic cells and neurons. We are developing the Cell Ontology as a metadata standard for annotation and analysis of experimental data in immunology in support of the National Institute of Allergy and Infectious Diseases (NIAID) ImmPort Immunology Database and Analysis Portal and Human Immunology Project Consortium. We have also developed ways to use the Cell Ontology in support of the analysis of gene expression data linked to cell types and have contributed to the Functional Annotation of the Mammalian Genome (FANTOM) 5 Consortium‘s work on identifying gene transcription start sites across multiple cell types and tissues. My research team is also developing the Neurological Disease Ontology to represent clinical and basic aspects of neurological diseases in order to support translational research in this area. In collaboration with clinical colleagues at UB, we are initially focusing on Alzheimer’s disease and dementia, multiple sclerosis and stroke. We have as well developed a companion ontology, the Neuropsychological Testing Ontology, to aid in the annotation and analysis of neuropsychological testing results used as part of the diagnosis of Alzheimer‘s disease and other neurological diseases. I am a long-term member of the Gene Ontology (GO) Consortium and have a particular interest in the representation of immunology and neuroscience in the GO. I am also involved in UB’s contribution to the Protein Ontology and contribute as well to the work of the Infectious Disease Ontology Consortium, Immunology Ontology Consortium and Vaccine Ontology Consortium. I teach and mentor students at the master’s and doctoral levels, and advise undergraduate, graduate, and medical students in summer research projects as well.
Children and Adults; Psychiatry; Molecular and Cellular Biology; Neuropharmacology; Signal Transduction
Research Interests: Calcium Metabolism in Affective Disorders; Psychopharmacology; Psychosomatic Medicine; Medical Education. Clinical specialties: mood disorders, psychosis, interactions between medical and psychiatric disorders, psychopharmacology, difficult diagnoses, complex clinical entities
Gastroenterology; Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular and Cellular Biology
Research in my laboratory concerns neurotransmitter and hormone-mediated anion secretion by gastrointestinal secretory tissues like intestinal crypts and liver ducts. I am determining the mechanisms that regulate the basolateral membrane K+ channel, KCNQ1, in anion secretion because these channels play a critical role in secretion by maintaining membrane potential as a driving force for anion exit across the apical cell membrane. Characterization of KCNQ1 K+ channels will help us to understand and remedy defects in anion secretion, especially in diseases like cystic fibrosis. I use electrophysiological techniques, including Ussing chamber, patch-clamp, and Fura-2 fluorescence techniques. I am also studying the mechanisms by which K+ channel antagonists (e.g., Zn2+) block KCNQ1 channels so that anti-secretory, anti-diarrheal drugs can be developed. I have past experience determining the mechanisms by which neurotransmitters regulate K+ channels via inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ release transduction pathways. I am also collaborating with Dr. John Crane to define the mechanisms by which Zn2+ inhibits the effects of Enteropathogenic E. coli (EPEC) on epithelial cell death and EPEC-stimulated phosphorylation and activation of the CFTR Cl- channel. There is considerable controversy concerning the role and basis of GI disorders associated with autism. In collaboration with Drs. Randall Rasmusson and Glenna Bett, I am investigating the mechanistic link between autism susceptibility and abnormal GI function. I propose that disorders of cellular Ca2+ homeostasis play a key role in the GI disorders of autism. Using mouse models derived from Cav1.2 Ca2+ channel defect that produces the human disorder, Timothy Syndrome, I am characterizing muscle tension and electrophysiological properties of the Ca2+ channel in intestinal smooth muscle. This information will lead to new approaches to identify therapeutic targets and treatments for autistic spectrum GI disorders and symptoms.
Oncology; Cell Cycle; Cell growth, differentiation and development; Gene Expression; Molecular Basis of Disease; Molecular and Cellular Biology; Signal Transduction; Transcription and Translation
Protein phosphorylation is an essential mechanism by which intercellular signals regulate specific intracellular events. Protein kinases, the enzymes catalyzing protein phosphorylation reactions, represent a major superfamily of genes, collectively representing 2% of the protein coding potential of the human genome. Current projects in Dr. Edelman‘s lab are devoted to the role of protein kinases in prostate and ovarian cancer. These projects utilize a wide range of techniques and involve, collaboration with investigators at Roswell Park Cancer Institute to develop protein kinase-targeted therapies for both types of cancer.
Neurology; Cytoskeleton and cell motility; Molecular and Cellular Biology; Molecular Basis of Disease; Molecular genetics; Neurobiology; Signal Transduction; Inherited Metabolic Disorders; Transgenic organisms
My laboratory seeks to understand the molecular basis of myelination and myelin diseases. Myelin is a multi-lamellar sheath that invests large axons and permits rapid conduction of nerve signals. Failure in myelin synthesis and myelin breakdown cause several important neurological diseases, including multiple sclerosis, leukodystrophies and peripheral dysmyelinating neuropathies. In some of these diseases, genetic mutations cause defects in cytoskeletal, adhesion and signaling molecules. I work with a team of undergraduate and graduate students, postdoctoral fellows, technicians, senior scientists and many international collaborators to discover how these molecules normally coordinate cell-cell and cell-extracellular matrix interactions to generate the cytoarchitecture of myelinated axons. We use a variety of approaches, including generation of mice carrying genetic abnormalities, cultures of myelinating glia and neurons, imaging, biochemistry and morphology to understand the role of these molecules in normal and pathological development. By comparing normal myelination to the abnormalities occurring in human diseases, we aim to identify molecular mechanisms that pharmacological intervention might correct. For example, we described how the protein dystroglycan associates with different proteins, some of which impact human neuropathies, depending on a proteolitic cleavage that can be regulated to improve the disease. Similarly, we found that molecules such as integrins and RhoGTPAses are required for glia to extend large processes that will become myelin around axons. In certain neuromuscular disorders, defective signaling pathways that converge on these molecules cause failure to produce or mantain an healthy myelin Finally, in collaborations with scientists and clinicians in the Hunter J. Kelly Research Institute, we are generating transgenic forms of GalC, an enzyme deficient in Krabbe leukodystrophy, to investigate which cells requires the enzyme. Investigating how GalC is handled may help find a cure for this devastating disease.
Neurology; Neurodegenerative disorders; Pathophysiology; Apoptosis and cell death; Cytoskeleton and cell motility; Molecular and Cellular Biology; Molecular genetics; Neurobiology; Protein Folding; Gene Expression; Transcription and Translation; Signal Transduction; Toxicology and Xenobiotics
My research is aimed at finding the cause and a cure for Parkinson’s disease. Parkinson’s disease (PD) is defined by a characteristic set of locomotor symptoms (rest tremor, rigidity, bradykinesia and postural instability) that are believed to be caused by the selective loss of dopaminergic (DA) neurons in substantia nigra. The persistent difficulties in using animals to model this human disease suggest that human nigral dopaminergic neurons have certain vulnerabilities that are unique to our species. One of our unique features is the large size of the human brain (1350 grams on average) relative to the body. A single nigral dopaminergic neuron in a rat brain (2 grams) has a massive axon arbor with a total length of 45 centimeters. Assuming that all mammalian species share a similar brain wiring plan, we can estimate (using the cube root of brain weight) that a single human nigral dopaminergic neuron may have an axon with gigantic arborization that totals 4 meters. Another unique feature of our species is our strictly bipedal movement, which is affected by Parkinson’s disease, in contrast to the quadrupedal movement of almost all other mammalian species. The much more unstable bipedal movement may require more dopamine, which supports the neural computation necessary for movement. The landmark discovery of human induced pluripotent stem cells (iPSC) made it possible to generate patient-specific human midbrain dopaminergic neurons to study Parkinson’s disease. A key problem for dopaminergic neurons is the duality of dopamine as a signal required for neural computation and a toxin as its oxidation produces free radicals. Our study using iPSC-derived midbrain dopaminergic neurons from PD patients with parkin mutations and normal subjects shows that parkin sustains this necessary duality by maintaining the precision of the signal while suppressing the toxicity. Mutations of parkin cause increased spontaneous release of dopamine and reduced dopamine uptake, thereby disrupting the precision of dopaminergic transmission. On the other hand, transcription of monoamine oxidase is greatly increased when parkin is mutated. This markedly increases dopamine oxidation and oxidative stress. These phenomena have not been seen in parkin knockout mice, suggesting the usefulness of parkin-deficient iPSC-derived midbrain DA neurons as a cellular model for Parkinson’s disease. Currently, we are using iPS cells and induced DA neurons to expand our studies on parkin to idiopathic Parkinson’s disease. We are also utilizing the molecular targets identified in our studies to find small-molecule compounds that can mimic the beneficial functions of parkin. The availability of human midbrain DA neurons should significantly speed up the discovery of a cure for Parkinson’s disease.
Apoptosis and cell death; Inherited Metabolic Disorders; Molecular Basis of Disease; Molecular and Cellular Biology; Neurobiology; Regulation of metabolism; Transgenic organisms; Vision science
Our lab is focused on studies of retinal degenerations caused by metabolic defects, particularly dyslipidemias involving defective cholesterol metabolism (e.g., Smith-Lemli-Opitz syndrome), using pharmacological and transgenic animal models. Current studies are focused on the role of lipid and protein oxidation in the underlying mechanisms of photoreceptor cell death in such retinal degenerations, using a combination of genomic, proteomic, and lipidomic approaches.
Bioinformatics; Genomics and proteomics; Immunology; Membrane Transport (Ion Transport); Molecular and Cellular Biology; Molecular Basis of Disease; Molecular genetics; Neurobiology; Gene Expression
The current focus of my lab is on iron metabolism in animals and humans. From the practical viewpoint, iron is an important nutrient, but its ability to act in the ferrous and ferric state also makes it toxic. Thus, iron deficiency is the most frequent disorder in the world and hereditary hemochromatosis (HH) is the most common Mendelian disorder in the United States. Our research is related to erythroid differentiation on the fundamental level and to genetic and acquired diseases on the applied level, with four long-term themes: 1.) analysis of the molecular basis of differential gene expression among tissues and during development, with hemoglobin synthesis and red blood cell (RBC) development as models; 2.) application of molecular and genetic advances to inherited diseases; 3.) iron metabolism; 4.) study of gene variation in populations and divergence of gene loci during evolution. New vistas have opened recently for the anemia of chronic diseases, leading us to re-exam how microbes and their human hosts fight for iron. We approach these issues by working on rodent models like the Belgrade rat, plus a series of genetically engineered mice. The rat has a hypochromic, microcytic anemia inherited as an autosomal recessive. The defect is in an iron transporter called DMT1 (or slc11a2, previously called Nramp2 or DCT1) that is responsible for iron uptake by enterocytes and is also responsible for iron exiting endosomes in the transferrin cycle. The rats appear to have a severe iron deficiency, and although dietary iron and iron injection increase the number of RBCs, they do not restore the RBCs nor the rat itself to a normal phenotype. Recent discoveries show that DMT1 is ubiquitous and responsible for transport of other metals such as Mn and Ni. It occurs in the kidney, brain and lung at even higher levels than in the GI tract or in erythroid cells. It also has multiple isoforms, and we have cloned them and developed cell lines that express high levels of particular isoforms. We have specific antibodies to the isoforms and assays for each of the mRNAs too. Future projects in my lab will continue to address whether DMT1 is dysregulated in HH. We will also tackle how DMT1 functions in neurons, pneumocytes and other tissues, look at isoforms of DMT1 under circumstances where we suspect that they must have different functions from one another, and examine DMT1’s relevance to iron metabolism and human disease. Because we cloned the gene and identified the mutation, a number of molecular and cellular approaches can now be used. As evidence indicates that metal ion homeostasis fails in Parkinson’s disease, Alzheimer’s disease and Huntington’s disease, research on DMT1 has opened new vistas for these disorders.
Bioinformatics; Cell growth, differentiation and development; Genomics and proteomics; Molecular and Cellular Biology; Molecular Basis of Disease; Molecular genetics; Neurobiology; Gene Expression; Stem Cells; Transgenic organisms
My research goal is to gain a better understanding of how proteins that interact with DNA regulate RNA transcription, DNA replication and metazoan development. I mentor undergraduate and graduate students in my lab; we focus on the structure and function of the Nuclear Factor I (NFI) family of site-specific DNA binding proteins, and we are investigating their roles in development. Our work has been made possible by our development of loss-of-function mutations of the NFI genes in the mouse and C. elegans. We are addressing four major questions in my laboratory and in collaboration with a number of talented collaborators: What is the structure of the NFI DNA-binding domain? How does NFI recognize and interact with DNA? Does NFI change the structure of DNA when it binds? What proteins interact with NFI to stimulate RNA transcription and/or DNA replication? These research questions are explored in my lab through two major projects focused on the role of NFIB in lung development and the role of NFIX in brain development. When NFIB is deleted from the germline of mice the animals die at birth because their lungs fail to mature normally. This provides a good model for the problems that occur with premature infants, whose lungs also fail to mature normally. We are using this model to determine how NFIB promotes lung maturation with the goal of being able to stimulate this process in premature infants. In our NFIX knockout animals, the brains of the animals are actually larger than normal and contain large numbers of cells in an area known to be the site of postnatal neurogenesis. We have evidence that NFIX may regulate the proliferation and differentiation of neural stem cells, which produce new neurons throughout adult life. Our aim is to understand the specific target genes that NFIX regulates in the adult brain to control this process of neurogenesis.
Molecular and Cellular Biology; Neurodegenerative disorders; Transcription and Translation; Signal Transduction; Toxicology and Xenobiotics
My lab studies the receptor signaling mechanisms for a family of neurotrophic factors that includes ciliary neurotrophic factor (CNTF), leptin, interferon gamma, and cardiotrophin-1. These factors use the Jak/STAT pathway to regulate neuronal survival, development and response to trauma. Our interests are in how activity of the receptors and their pathway components are regulated. Currently this has focused on the impact of cellular oxidative stress on the inhibition of Jak tyrosine kinase activity. Increases in oxidative stress in neurons result in the blockade of not only CNTF family factor effects, but of many other cytokines that also use the Jak/STAT pathway for signaling such as interferons and interleukins. Non-nerve cells appear resistant to these effects of oxidative stress. Ongoing projects include testing the theory that environmental contaminants known to increase oxidative stress in cells may promote neurodegenerative diseases by inhibiting growth factor signaling. We have been studying the effects of certain heavy metals (cadmium & mercury) and pesticides (e.g. rotenone) on nerve cells in culture to determine the molecular basis for Jak inhibition. Another examines a possible role of oxidative stress in obesity. This study tests the hypothesis that the loss of the ability of the hormone leptin to regulate metabolism and appetite during obesity is a result of oxidative reactions that inhibit Jak-mediated signaling in the hypothalamus and other brain regions.
Mucociliiary Transport; Cell growth, differentiation and development; Cytoskeleton and cell motility; Molecular and Cellular Biology; Signal Transduction
Our lab is involved in two major projects: 1) Cell motility research – mucociliary transport. We have developed a series of real “models” or simplifications of the respiratory mucociliary epithelium (primary cultures, isolated epithelial sheets, isolated ciliated cells, demembranated and MgATP-reactivated cell models, and isolated, demembranated and reactivated ciliary axonemes) that allow one to study mucociliary transport at number of levels of organization. We have studied these models using biochemical methods, stroboscopic imaging, high speed image analysis, and EM to analyze the control of the beat frequency, waveform and coordination of respiratory cilia. We have developed correlative LM/EM methods and correlative live/immunofluorescence methods for this purpose. These studies have import for 1) detecting and understanding abnormal parameters of ciliary function, as in primary ciliary diskinesis (PCD) 2) for the testing of exogenous agents (drugs, environmental agents, etc.) on mucociliary transport. 2) Along with 4 other UB labs in Chemistry and Engineering, plus 1 lab in Head and Neck Surgery Dept. at Roswell Park, our lab is involved in an interdisciplinary project to develop a “high tech bandage” that is doped with tissue specific growth factors and cytokines that can be released with full activity and at known rates to stimulate wound healing in scrape and burn types of acute (and potentially, chronic) injuries. These agents are selected to promote: a) the motogenic and mitogenic activity of epithelia and b) blood vessel formation. Our lab specifically is responsible for the in-vitro testing of doped membranes for their ability to promote wound closure (re-epithelialization of 9 mm wounds) in a human epidermal cell line by image analysis of wound closure kinetics and cell division and cell death rates. We also are responsible for the in-vivo testing of such membranes in animals using a porcine burn model to assay inflammation, epithelial closure rates, blood vessel formation, and inflammation. As a faculty member and Co-Director of one of the oldest biological imaging courses in the U.S. (Optical Microscopy and Imaging in the Biomedical Sciences Course, Marine Biology Laboratory, Woods Hole, MA) my lab frequently is asked to help other researchers with digital imaging problems and has contributed computerized digital image analyses in a number of scientific publications.
Neuroimmunology; Behavioral pharmacology; Gene therapy; Immunology; Molecular and Cellular Biology; Molecular Basis of Disease; Neurobiology; Gene Expression; Signal Transduction; Protein Function and Structure; Neuropharmacology
My research spans three interrelated fields: chronic pain, depression and inflammation. Experiments in my laboratory focus on how brain-derived pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF), function as modulators of brain-body interactions during neuropathic pain and how brain-TNF is involved in the mechanism of action of antidepressant drugs. My overall goal is to advance knowledge of, and therapeutic efficacy for pain, depression, neuro-inflammation and drug addiction. This research is based on my earlier work showing that neurons produce the pro-inflammatory cytokine TNF and that the production of TNF by macrophages is regulated by neurotransmitters. Cytokines and neurotransmitters are principal signaling molecules that mediate bidirectional communication between the nervous and immune systems--the crosstalk important in maintaining homeostasis. Consequently, aberrant production of either of these two classes of mediators could profoundly affect signaling by the other, thereby impacting health. A shift in balanced cytokine-neuron interactions that regulate neurotransmitter release in the central nervous system (CNS), and that have potential behavioral consequences, manifest themselves as states of depression and chronic pain. My research uses both cell systems and animal models to test these hypotheses. Colleagues and I use a combination of imaging techniques to localize cytokine production, bioassays and ELISA (enzyme-linked immunosorbent assays) for pharmacological and functional analyses, electrophysiological (brain slice stimulation) and molecular methods for our studies. In addition to investigating neuron functioning in the brain, trainees in my laboratory also study the peripheral macrophage, a major source of TNF during inflammation. Specifically studying neurotransmitter regulation of TNF production in the periphery is enhancing our knowledge of how the brain controls a peripheral inflammatory lesion. Our studies are designed to investigate the mechanisms of centrally mediated pain as associated with immune dysfunction and to elucidate mechanisms of drugs used to treat such pain states. My projects are evolving to investigate the mechanisms and neural pathways involved in TNF neuromodulator functions during chronic pain (due to peripheral nerve injury and diabetes) and stress-induced depressive behavior. We also study mechanisms contributing to the comorbidity of chronic pain and depression. I collaborate with researchers in several UB departments and at other institutions. Our projects include using noninvasive methods for delivery of anti-TNF therapeutics for chronic pain, elucidating the neural-immune mechanisms involved in the rapid recovery afforded by centrally administered anti-TNF therapy and using nanotechnology-mediated, targeted gene silencing within the CNS. I am invested in helping my undergraduate and graduate students, medical residents and postdoctoral fellows realize their potential and achieve their goals. Previous students have advanced professionally and hold clinical, academic and industrial positions.
Anatomic Pathology; Biomedical Imaging; Molecular and Cellular Biology
I am a classically trained gross anatomist with a specific interest in clinical anatomy. Although I received my PhD through the Interdisciplinary Program in Molecular and Cellular Biology at Ohio University, with a specific focus on skeletal muscle biology, my professional interest and focus since graduation has been in the teaching of the anatomical sciences, and in educational research and theory, in general. I am also involved in the development of anatomical models for teaching purposes and in research and documentation of anatomical variants identified during gross anatomy dissection. Presently, I am one of the instructors for the ANA 500 gross anatomy course for the medical and dental students and serve as the coordinator for the dental section of the course. I also serve as course director for the ANA 407 gross anatomy course for OT, PT, and exercise science students. My educational research interests involve the development and execution of a flipped classroom approach to teaching, with the replacement of traditional didactic lectures with facilitated active learning (FAL) sessions. The traditional university classroom, in which a content expert lectures and students take notes, dates back to the earliest universities and predates the printing press. This was therefore the most effective and efficient means by which to disseminate knowledge. Current technology makes this approach unnecessary, and allows instructors to explore other teaching approaches that may improve retention and help develop lifelong learning strategies. Pre-recorded lectures give students more control over the time and pace at which they view the didactic sessions. My classroom sessions are modelled after the Team Based Learning (TBL) paradigm and make use of the latest in audience response technology. I am also interested in the utilization of Open Educational Resources (OER) to deliver lessons to a wider population base without violating copyright restrictions.
Gene Expression; Immunology; Molecular and Cellular Biology; Molecular genetics; Signal Transduction
I am the administrator for flow cytometry in the Confocal Microscopy and Flow Cytometry Core Facility that serves investigators throughout the university. In that role, I oversee the use of the LSRFortessa and the FACSCalibur analytical flow cytometers, providing instruction on their use and the analysis of acquired data and serving as a consultant on the design and interpretation of experiments. I also operate the FACSAria cell sorter, providing sterile live cell sorting. In addition, I operate and provide assistance to users on the application of cytometric bead array analysis on the FACSArray, as well as Elispot analysis using the Zeiss KS-ELISPOT microscope. My own research centers on investigating the responsiveness of human T cells in the tumor microenvironment of lung and ovarian cancer and lymphomas. In that research, I am a coinvestigator in a collaborative group of oncologists and immunologists coordinated by Richard Bankert, PhD. We have observed that T cells in the tumor microenvironment are hyporesponsive to T cell receptor-mediated activation and that factor(s) present in ovarian tumors and associated ascites fluid can cause this hyporesponsiveness. We are investigating the mechanism(s) of this phenomenon. Also, as an approach to the in vivo study of the immune response to human tumor associated antigens, our group has established a novel xenograft model by injecting human tumor cell aggregates of solid ovarian tumor biopsies intraperitoneally into immune-deficient NSG mice. The result is a human tumor microenvironment in the greater omentum of the mice, i.e., the omental tumor xenograft (OTX) model. The progression of the human tumor xenograft closely approximates the characteristics of the tumor in cancer patients, and it is possible to quantify the presence of tumor cells and stromal cells in the OTX model. These findings have led to our program goals to: 1.) determine whether the OTX model can be used as a predictive tool of the outcome of therapeutic approaches for the treatment of human ovarian cancer and B cell lymphoma, and 2.) determine whether the inhibition of activation in the tumor microenvironment can be reversed so that the antitumor T cell response can be reactivated.
Cardiovascular Disease; Cytoskeleton and cell motility; Molecular Basis of Disease; Molecular and Cellular Biology
My primary research interest is the behavior of endothelial cells, which form the inner lining of blood vessels and are key players in the remodeling events that occur during wound healing, aneurysm formation, tumor growth, and a wide variety of disease conditions. There are two questions about endothelial behavior that drive most of the research in my laboratory: (1) How does an endothelial cell migrate during wound healing and blood-vessel remodeling? We are particularly interested in the motor protein, myosin II, and how it exerts force within the cytoskeleton to push or pull the cell as it moves. In order to study the organization and movements of cytoskeletal proteins - and not just there biochemical properties - we use a variety of light microscopic methods to examine the dynamics and biochemistry of cytoskeletal proteins in living migrating endothelial cells. We also use conventional biochemical, genetic, and pharmacological manipulations to investigate the regulatory events that control myosin II behavior in situ. (2) How do endothelial cells sense and respond to their mechanical environment? Blood vessels remodel to accommodate long-term changes in blood flow. Certain flow environments can cause destructive remodeling that leads to cerebral aneurysms (local “ballooning” of vessels). Working with biomedical engineers in the laboratory of Dr. Hui Meng at the Toshiba Stroke Research Center, we use cell culture and whole animal systems to examine how endothelial cells respond to specific hemodynamic micro-environments in order to understand the mechanism and regulation of flow-induced remodeling, especially as it relates to cerebral aneurysms. A third interest is understanding the response of cultured endothelial cells to electrical fields, which have been shown to orient endothelial migration in vitro and to suppress edema in vivo by enhancing the endothelial permeability barrier.
Cardiology; Cardiovascular Disease; Cell growth, differentiation and development; Gene Expression; Molecular and Cellular Biology; Signal Transduction; Stem Cells
As a general cardiologist, I diagnose and treat a wide range of problems that affect the heart and blood vessels, including but not limited to coronary artery disease, valvular heart disease, heart failure, diseases of the myocardium and pericardium, cardiac arrhythmias, conduction disorders and syncope. I attend on the inpatient Coronary Care ICU (CCU), Cardiac Step-down Unit, and Cardiology Consult service at Buffalo General Medical Center as well as see patients in my outpatient clinic. In addition to treating pre-existing cardiac conditions, I also believe in strong preventive care and addressing modifiable risk factors for coronary disease. I take time to get to know my patients, and I talk with them about measures they can take to reduce their risk for cardiovascular disease and improve their health. As a clinician-scientist, I have a special interest in developing new stem cell based treatments for heart disease. My research is focused on understanding what stem cell secreted factors are responsible for improved heart function, what their targets are and how these can be modulated to develop new cell-free therapies that can help patients with a wide spectrum of coronary disease and heart failure. I welcome medical students, graduate students, residents and fellows to conduct research with me in my lab. As a native Buffalonian, I am honored to partner with the patients in our community to help improve their heart health and cardiac knowledge base. I am equally excited to be involved in shaping the next generation of physicians through the teaching I conduct at the medical student, resident and fellow level.
Apoptosis and cell death; Endocrinology; Molecular and Cellular Biology; Gene Expression; Regulation of metabolism; Signal Transduction
Suzanne Laychock, PhD, is senior associate dean for faculty affairs and facilities, and professor of pharmacology and toxicology. She is responsible for overseeing faculty development, space management, and undergraduate biomedical education programs. Dr. Laychock earned a bachelor’s degree in biology from Brooklyn College, a master’s degree in biology for the City University of New York and a doctorate in pharmacology from the Medical College of Virginia. An accomplished scientist, Dr. Laychock’s research focuses on endocrine pharmacology with an emphasis on signal transduction mechanisms involved in insulin secretion and models of diabetes mellitus. The author of numerous journal articles, she has served as associate editor of the research journal LIPIDS, and on the editorial boards of Diabetes and the Journal of Pharmacology and Experimental Therapeutics. She is the recipient of research grants from, among others, the Juvenile Diabetes Research Foundation, the National Institutes of Health, and the American Diabetes Association. Dr. Laychock is Council Member and has chaired the Women in Pharmacology Committee of the American Society for Pharmacology and Experimental Therapeutics. She has served the university as a member and chair of the President’s Review Board, and as co-director of the Institute for Research and Education on Women and Gender.
Apoptosis and cell death; Bioinformatics; Endocrinology; Gene Expression; Gene therapy; Genomics and proteomics; Immunology; Molecular Basis of Disease; Molecular and Cellular Biology; Neurobiology; RNA; Viral Pathogenesis
Dr. Mahajan has established herself as an investigator in the area of neuropathogenesis of HIV-1 in the context of drug abuse. She has initiated several new projects that investigate the role of a unique key signaling molecule in the dopaminergic pathway that impacts drug addiction, depression and other neurological disorders. Her focus has always been on collaborative, interdisciplinary partnerships between various Departments within UB that include the Institute of Lasers, Photonics and Biophotonics, Research Institute of Addiction, Dept of Computer Science and Engineering, Dept of Pharmaceutical sciences and the Department of Bioengineering. This inclusive strategy has facilitated the emergence of a robust, innovative clinical translational research program for our Division that continues to grow steadily. Dr Mahajan has obtained independent research funding from NIDA, the pharmaceutical Pfizer, US- Fulbright and other Private Foundations such as Dr. Louis Skalrow Memorial trust to conduct some of these research projects. Dr. Mahajan is Director of Research of the Division of Allergy, Immunology & Rheumatology. She supervises the research training of the Allergy fellows,Medical residents, graduate and undergraduate students. Dr. Mahajan has presented her research work at National and International conferences and was an invited speaker at several seminars and colloquiums. She has authored over 95 publications in several top quality peer reviewed journals and has thus demonstrated a high level of scholarly productivity. She is a reviewer and an adhoc member of the editorial board of several journals in her field. The following is a brief synopsis of her research interests. HIV neuropathogenesis in the context of drug abuse: We proposed that Opiates act as co-factors in the pathogenesis of HIV-1 infections by directly suppressing immune functions of the host through interactions with mu-opioid receptors on lymphocytes. Exacerbation of HIV encephalopathy (HIVE) is observed with opiate abuse. The mechanisms underlying HIVE are currently undetermined however, they likely to include the generation of endogenous neurotoxins combined, perhaps synergistically, with bioreactive HIV-1 envelope proteins. We believe that these proposed mechanisms may work through a common signal transduction mechanism activating dopamine D1 receptors in the nucleus accumbens of the brain. Opiate abuse by HIV-1 infected subjects may exacerbate the progression of HIVE as a consequence of the combined effects of HIV-1 induced neurotoxins plus opiate induced increases in the D1 receptor activation. We hypothesize that the dopaminergic signaling pathway is the central molecular mechanism that integrates the neuropathogenic activities of both HIV-1 infections and the abuse of opiate drugs. In this context our investigation is focused on the DARPP-32 signalling pathway. Addictive drugs act on the dopaminergic system of the brain and perturb the function of the dopamine- and cyclic-AMP-regulated phosphoprotein of molecular weight 32 kD (DARPP-32). DARPP-32 is critical to the pathogenesis of drug addiction by modulating both transcriptional and post-translational events in different regions of the brain. DARPP-32 is localized within neurons containing dopamine receptors and is a potent inhibitor of another key molecule in the dopaminergic signaling pathway, protein phosphatase 1 (PP-1). We propose that the sustained silencing of DARPP-32 gene expression using specific siRNA delivered to the brain is an innovative approach for the treatment of drug addiction. The specific challenge of the proposed project is the non-invasive delivery of biologically stable, therapeutic siRNA molecules to target cells within the brain. We are developing biocompatible nanoparticles to both protect DARPP-32 specific siRNA against degradation and deliver it from the systemic circulation across the BBB to specific dopaminergic neurons in the brain of patients with opiate addictions. BBB Research: While examining neuropathogenesis of HIV, we became interested in the role of the blood-brain barrier (BBB) in HIV neuropathogenesis with the objective of developing therapeutic interventions to prevent and limit the progression of HIV associated neurological disease. The blood-brain barrier is an intricate cellular system composed of vascular endothelial cells and perivascular astrocytes that restrict the passage of molecules between the blood stream and the brain parenchyma. We evaluated and validated both the 2 and 3 dimensional human in-vitro BBB models in my laboratory, that allowed examining permeability of virus, effects of drugs of abuse on BBB permeability, mechanisms of BBB transport, and tight junction modulation. Our goal remains to determine the impact of current and potential CNS antiretrovirals, psychopharmacologic, and other medications on the integrity of the BBB in HIV associated neurological disorder and other neurodegenerative diseases. Additionally, We also investigate mechanisms that underlie drugs of abuse induced neuronal apoptosis. Systems biology approach: We expanded our investigation to include functional genomic/proteomic analyses that allowed characterization of gene/ protein modulation in response to a drug stimulus or under a specific disease condition. We developed an expertise in these large-scale genomic and proteomic studies and the genomic studies helped identify key genes that underlie molecular mechanisms in drug addiction, HIV diseases progression, and allowed examination of the interplay of genes and environmental factors. The proteomic studies confirmed the presence of specific proteins that regulate key biological processes in drug addiction and HIV diseases progression. Recently, We have expanded my research program to include microbiome analyses and incorporated the utility of the computational drug discovery platform (CANDO) model that allows studying interaction between protein structures from microbiome genomes and determine the interactions that occur between them and small molecules (drugs and human/bacterial metabolites that are already a part of or continue to be added to the CANDO library. Using the CANDO Platform we are able to do the hierarchical fragment-based docking with dynamics between those compounds/drugs and the microbiome proteins/proteomes to determine which ones of the drugs and metabolites will work most efficaciously in patients using specific drugs. NanoMedicine: Over the last couple of years, We have become increasingly interested in nanomedicine and have developed several interdisciplinary clinical translational research focused collaborations that include 1) Nanotechnology based delivery systems to examine antitretroviral transport across the BBB; 2) Nanotherapeutics using siRNA/Plasmid delivery to specific regions in the brain to target various genes of interest specifically those pertaining to the dopaminergic pathway that includes a phosphor protein called “DARPP-32”. Targeting various key genes in the dopaminergic pathway results in the modulation of behavioral response which we observed in animal models of addiction/depression, 3) Biodistribution studies of various nanotherapeutic formulations using PET small animal imaging. Additionally, We are also focused on exploring epigenetic mechanisms that under drug addiction and mechanisms that underlie oxidative stress in neurodegenerative diseases.
Infectious Disease; Microbiology; Molecular and Cellular Biology; Molecular genetics; DNA Replication, Recombination and Repair; Virology; Genome Integrity
The major focus of my laboratory is in understanding the molecular machines that make up the DNA replication forks of the small human DNA viruses, polyoma- and papillomaviruses. Papillomaviruses and polyomaviruses are human pathogens; human papillomavirus (HPV) results in a vast number of human cancers, and the human polyomaviruses JC and BK cause serious disease and death in immunocompromised patients. Both viral systems provide important models for the study of human DNA replication mechanisms and have allowed for vital insights into eukaryotic DNA replication. The study of polyomavirus DNA replication led to the first identification of many cellular DNA replication complexes and processes; papillomavirus has provided the best structures and models to date of replicative hexameric DNA helicases and how they function. I typically train undergraduate, master’s and doctoral students and postdoctoral scholars, assistant research professors and laboratory technicians. My laboratory focuses on two primary areas. One is elucidating the dynamic protein-protein interactions that allow the series of enzymes required to replicate DNA to act in concert and in the correct sequence required to duplicate the genome. My laboratory has been at the forefront of identifying the interactions between the one critical HPV DNA replication protein, the origin-binding DNA helicase, E1, and cellular DNA replication proteins. Understanding these interactions and the roles they play in the HPV DNA replication process has helped our understanding of, and continues to lead to information that tells us more about how both viral and eukaryotic DNA replication forks function. In addition, as we identify protein-protein interactions between HPV E1 and cellular factors that are essential for HPV DNA synthesis, we will uncover potential targets for development of broad-range HPV antivirals that could act to block HPV replication. We recently obtained a large multilaboratory NIH research grant to investigate just this possibility for the interaction between HPV E1 and the human DNA replication protein, Topoisomerase I. The second primary area of investigation is elucidating how the cellular DNA damage response (DDR) pathways inhibit DNA replication when cells are subjected to DNA damage. For many years, the DDR field focused on the effects of DDR on the cell cycle kinases as the only method by which DNA replication was arrested. In the mid- to late-2000s, researchers recognized that in mammalian cells there is also a substantial (tenfold) inhibition of elongation of DNA replication following DDR. The mechanisms for this inhibition are unknown. Using both in vitro and cell-based simian virus 40 (SV40) DNA replication systems, we have shown that SV40 DNA replication is also shut down in response to DDR kinase pathways and that this is not based on cell cycle kinase action. Therefore, SV40 provides a useful model system for determining how elongation of DNA replication is inhibited by DDR. Furthermore, we have shown that in contrast HPV DNA replication does not respond to DDR, providing us an important control DNA replication system for these studies. (The lack of DDR arrest of HPV DNA replication likely explains why HPV integrates so readily into host cell chromosomes−an important step for HPV-induced carcinogenesis). Our studies on the DDR effect on polyoma and papilloma virus DNA replication will lead to insights into the effect of DDR on cellular DNA replication as well as an understanding of how HPV integrates into host cell chromosomes causing HPV-induced cancers.
Microbial Pathogenesis; Molecular and Cellular Biology; Gene Expression; Regulation of metabolism
The adaptive success of bacteria depends, in part, on the ability to sense and respond to their environment. Metals such as iron and manganese are important nutrients that can often be limiting, and therefore cellular metabolism must be modified to either scavenge the nutrients or use alternative processes that do not require the metal. Bradyrhizobium japonicum belongs to a group of related organisms that form close or intracellular and related bacteria that form an intracellular relationship with eukaryotes in a pathogenic or symbiotic context. This bacterium serves as a model to study related pathogens that are refractive to genetic and biochemical study. One project involves understanding the mechanisms by which cells maintain iron homeostasis at the level of gene expression. We discovered the global transcriptional regulator Irr that controls iron-dependent processes. Irr is stable only under iron limitation, where it positively and negatively controls target genes. We are interested in understanding the mechanism of this conditional stability, how Irr regulates genes, and the functions of numerous genes under its control. We initiated a new project to understand the requirement for manganese in cellular processes, how it is acquired from the environment, and how manganese controls gene expression. Also, we identified cross-talk between regulators that control iron and manganese homeostasis and are pursuing this unique mechanism.
Ion channel kinetics and structure; Molecular and Cellular Biology; Neurobiology; Neuropharmacology
Our research program focuses on brain development, studying the development of the oligodendroglial and astroglial cell lineages in the central nervous system in normal, mutant and transgenic mice. The primary focus in the laboratory is on ion channels that regulate specification, migration and differentiation of these glial cells. The oligodendrocyte generates CNS myelin, which is essential for normal nervous system function. Thus, investigating the regulatory and signaling mechanisms that control its differentiation and the production of myelin is relevant to our understanding of brain development and of adult pathologies such as multiple sclerosis. We have recently discovered that voltage-gated Ca++ channels are necessary for normal myelination acting at multiple steps during oligodendrocyte progenitor cells (OPCs) development, however nothing is known about its role in demyelination or remyelination events. Our research aims to determine if voltage-gated Ca++ channels plays a functional role in myelin repair. Using transgenic mice and new imaging techniques we are testing the hypothesis that voltage-gated Ca++ entry promotes OPC survival and proliferation in the remyelinating adult brain. Therefore, this work is relevant to developing means to induce remyelination in myelin degenerative diseases and for myelin repair in damaged nervous tissue. Astrocytes are the most abundant cell of the human brain. They perform many functions, including biochemical support of endothelial cells that form the blood brain barrier, provision of nutrients to the nervous tissue and a role in the repair and scarring process of the brain and spinal cord following traumatic injuries. Our lab has made the novel finding of voltage-gated Ca++ channels function in astrocyte Ca++ homeostasis, and this has implications for plasticity in astrocyte development and for Ca++ regulation in general. We are testing the hypothesis that voltage-gated Ca++ entry plays a key role in astrocyte function and glial-neuronal interactions. We have generated a conditional knockout mice for voltage-gated Ca++ channels in astrocytes, these conditional knockout mice will allow the functional analysis of voltage-gated Ca++ channels in astroglia of the postnatal and adult brain. Analyzing such mice using a combination of behavioral, electrophysiological, imaging, and immunohistochemical techniques will provide new insights in our understanding of astroglial contribution to brain function. These projects have been supported for many years by grants from the NIH and the National Multiple Sclerosis Society.
Inherited Metabolic Disorders; Membrane Transport (Ion Transport); Molecular Basis of Disease; Molecular and Cellular Biology; Molecular genetics; Protein Function and Structure; Transgenic organisms; Vision science
Most physiological processes and numerous disease states influence or are influenced by pH. Even relatively small deviations in whole body pH can have devastating consequences for our health. Our bodies are subject to a constant challenge from dietary and metabolic acids, thus it is critical for the body to have mechanisms that tightly regulate pH. Blood plasma pH is maintained at a value close to 7.4, predominantly thanks to the buffering action of 24 mM bicarbonate (HCO3-). HCO3- neutralizes acid, generating carbon dioxide and water (HCO3- + H+ to CO2 + H2O), preventing lethal acidosis. I study the SLC4 family of membrane proteins that move acid/base equivalents across cell membranes. Notable members include  the Na/2HCO3 cotransporter NBCe1-A that reclaims HCO3- from filtered blood plasma in kidney tubules (preventing loss of vital plasma HCO3- to the urine),  NBCe1-B that promotes fluid removal from the corneal stroma (preventing corneal edema and vision loss),  the Cl-HCO3 exchanger AE1 that promotes O2-CO2 exchange in red blood cells, and  SLC4A11 that conducts H+ and promotes corneal clarity. Dysfunction of SLC4 family members is associated with renal tubular acidosis, blindness, cancer, deafness, epilepsy, and hypertension.
Gene Expression; Molecular Basis of Disease; Molecular and Cellular Biology; Molecular genetics; Protein Function and Structure; Transcription and Translation
Our laboratory uses genetic, biochemical and molecular biological approaches to study the molecular mechanisms of eukaryotic transcription initiation and regulation. Previous work in our laboratory utilizing both the budding yeast Saccharomyces cerevisiae and human cells resulted in the identification and biochemical characterization of mutants of nuclear RNA polymerase II (RNAPII) and the general transcription factors TFIIB and TFIIF that coordinately affect transcription start site utilization and transcript elongation. These studies supported a model where yeast and human TFIIF induce global conformational changes in RNAPII that result in structural and functional changes in the polymerase active center. Our current work is aimed toward gaining a better understanding of the mechanisms of kinetoplast transcription by the mitochondrial RNA polymerase of Trypanosoma brucei. T. brucei is a protozoan parasite that is the causative agent of African sleeping sickness (trypanosomiasis) in humans and nagana in animals. Procyclic trypanosomes growing in the midgut of the tsetse fly have fully functional mitochondria whereas trypanosomes in the mammalian bloodstream display repressed mitochondrial function. The mitochondrial DNA in trypanosomes is unusual in its structure, comprising a highly catenated network of maxicircles and minicircles termed kinetoplast DNA (kDNA). Our objective is to elucidate the mechanisms and regulation of T. brucei maxicircle and minicircle transcription.
Gene Expression; Gene therapy; Molecular Basis of Disease; Molecular and Cellular Biology; Neurobiology; Neuropharmacology; Transcription and Translation
The efforts in my lab are broadly directed at the translational research of neuroprotective/neurorestorative agents. Specifically, I am focused on the preclinical and clinical development of therapies used to prevent behavioral and cognitive deficits following traumatic brain injury (TBI) and stroke. Over 800,000 patients each year in the US suffer stroke and more than twice that number suffer TBI. Unfortunately there are currently no FDA approved therapies for TBI. TPA is the only therapy approved for stroke but is only applied in about 4% of stroke patients. Furthermore, while TPA is thrombolytic, it does not limit the cascade of pathology initiated by the original occlusion. We have demonstrated that low dose methamphetamine is highly neuroprotective when administered as an acute treatment (within 12 hours after injury) following severe stroke or TBI. We have show that treatment with methamphetamine significantly improve cognition and functional behavior in rat models of these injuries. This effect is primarily mediated through the activation of a dopamine/PI3K/AKT signaling cascade and results in the preservation of primary neurons, and axons, as well as enhanced granule cell neurogenesis and white mater track remodeling. Furthermore, gene expression analysis suggests methamphetamine treatment significantly reduces pro-inflammatory signals and stabilizes the blood brain barrier. These observations led us to further investigate the potential of low dose methamphetamine to reduce or prevent post-traumatic epilepsy. Using long-term video/EEG monitoring, we determined that methamphetamine treatment significantly reduces the incidence and susceptibility to post traumatic epilepsy/seizures after severe TBI in rats. This becomes quite relevant when one considers that many patients with post-traumatic epilepsy are pharmacoresistant. We are continuing to use the TBI model to investigate the causes of post-traumatic epilepsy and test novel therapeutics. In addition to single severe injury, we are also very interested in the effects of repeated mild TBIs. It has now been observed that multiple mild TBIs can cause clinical seizures in about 50% of rats. Therefore, we are also using this model to investigate the causes of post-traumatic epilepsy and potential therapeutic interventions. We have now completed a phase I human trial of methamphetamine in healthy volunteers and are moving to conduct a phase IIa dose escalation safety study in TBI patients. In addition, we are currently using NGS to examine plasma miRNA changes as potential biomarkers and objective measures of activity to support the phase IIa study. In addition to small molecules, my lab also is investigating the development of Adeno- associated virus (AAV) vector based gene therapy approaches to the treatment of CNS injuries such as post-traumatic epilepsy. Specifically, we are using recombinant AAV vectors to modulate targeted gene expression in a temporal, tissue-specific and cell type-specific manner within the CNS.
Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular Basis of Disease; Molecular and Cellular Biology; Protein Folding; Protein Function and Structure; Signal Transduction
Work in my lab seeks to elucidate the transduction mechanisms of ion channels involved in thermal sensation and pain, such as the heat-activated vanilloid receptors (TRPV1-4) and the cold-activated TRPM8 – the so-called thermal TRP channels. Expressed in peripheral afferent nerve endings, these channels function as an array of thermometers for sensing ambient temperature from noxious cold to noxious hot. While all proteins are thermally sensitive, thermal TRP channels are gated by temperature and possess unprecedentedly high temperature dependence. But the mechanisms of their temperature gating has remained mysterious, in contrast to our abundant knowledge on other types of ion channel gating (e.g. voltage or ligand-driven). Thermal TRP channels are also distinct for their polymodal responsiveness. TRPV1, for example, is responsive to heat, voltage, pH, capsaicin (i.e. the hot ingredient of chili peppers) among many other irritant compounds. The channels are thus informative for deciphering how biological proteins achieve multitasking. Thermal TRP channels also have receptor-like roles in mediating intracellular signaling. The calcium influx through the channels has potentially a broad spectrum of functional consequences, one of which is the desensitization of the channels themselves, a phenomenon that is believed to underlie peripheral analgesics. Our research is centered on problems like these, and we approach them by a combination of techniques such as recombinant mutagenesis, patch-clamp recording, fluorescence measurements, quantitative modeling, etc, which together allow us to draw insights into functions of the channels at mechanistic levels. Complementing our experimental studies, we are also interested in development of methodology to ever extend experimental resolutions. For example, to time-resolve temperature-dependent activation of thermal TRP channels, we have developed a laser diode-based temperature clamp apparatus, which achieves for the first time a submillisecond resolution (>105 oC/s) while capable of clamping temperature constant. For the past decade we have also been developing sophisticated algorithms for statistical analysis of single-molecule measurements such as single-channel patch-clamp recordings, which can help unravel the richness of data pertaining to molecular mechanisms at high resolutions. Together, these approaches provide us with unique abilities for in-depth studies of structure-mechanisms of ion channels.
Drug abuse; Apoptosis and cell death; Molecular and Cellular Biology; Neurobiology; Signal Transduction; Toxicology and Xenobiotics
My laboratory is focused on understanding the molecular and cellular actions of drugs of abuse such as ethanol and hallucinogens such as lysergic acid diethylamide (LSD). This information is a requisite step in the ultimate development of therapeutic interventions to alleviate the major healthcare and social burden associated with use and abuse of these drugs. In addition, these drugs provide an avenue to explore the basic workings of the brain under pathological conditions that are manifested as various psychiatric disorders. Previous studies, in collaboration with Dr JC Winter in the Dept of Pharmacology and Toxicology at UB, have investigated the roles of the various serotonin receptors subtypes and their associated signaling pathways as well as glutamatergic neurotransmission in the subjective effects of LSD-type hallucinogens. Our other studies have been aimed at understanding the adverse developmental effects of ethanol exposure that result in the fetal alcohol spectrum disorders with the fetal alcohol syndrome (FAS) as the most severe manifestation. Using zebrafish and neuronal cells in culture as model systems, my laboratory in collaboration with Dr CA Dlugos in the Dept of Pathology and Anatomical Sciences at UB have investigated the morphological and histological changes associated with ethanol exposure during different developmental stages as well as the mechanisms by which developmental ethanol exposure causes neuronal loss. Currently, we are investigating the neurotoxic interaction of ethanol with pesticides. Because of the wide-spread use of pesticides, people are continually exposed both voluntarily and involuntarily to an array of toxic chemicals. In addition, since consumption of alcohol is pervasive in our society with a very high prevalence of alcohol use and abuse, it is extremely likely that people with be co-exposed to both ethanol and pesticides. Because simultaneous or sequential exposure to multiple chemicals can dramatically modify the ensuing toxicological responses, we are using both in vitro (e.g., cells in culture) and in vivo (e.g., zebrafish) model systems to begin assessing the possible health risk of co-exposure to ethanol and pesticides. Using the herbicide paraquat, which is widely used throughout the world, as a test compound, we have found that ethanol synergistically increases the in vitro neurotoxicity of this pesticide. Our efforts are now aimed at ascertaining whether a similar interaction occurs in vivo as well as determining the molecular mechanism responsible for this synergistic neurotoxicity. Teaching is a naturally complement to research. Accordingly, I have also been engaged in efforts to both improve how we provide the knowledge base to our undergraduate, graduate, and professional students, and also how we help students learn to integrate and apply this information in problem-solving at the clinical and basic science levels. Efforts include: 1. using “clickers” in large class formats to assess student’s understanding of the material and well as provide each student instantaneous feedback for their own self-assessment; 2. using cases studies and a small group learning format; and 3. Having students write short grant proposals based upon the current literature as well as reviewing and critiquing their classmate’s proposals.
Eukaryotic Pathogenesis; Gene Expression; Genomics and proteomics; Infectious Disease; Microbial Pathogenesis; Microbiology; Molecular and Cellular Biology; Molecular genetics; Protein Function and Structure; RNA
Trypanosoma brucei is a eukaryotic pathogen that causes human African trypanosomiasis, a disease that is invariably fatal if not treated. Essential and novel processes in this parasite may serve as starting platforms for new chemotherapeutics, which are urgently needed. Our laboratory combines biochemical, genetic, genomic and proteomic approaches toward understanding gene regulation and protein modification in this pathogenic eukaryote. One focus in my laboratory is RNA editing, a novel mechanism for regulating mitochondrial gene expression in which sequence information is added to mRNAs after transcription by specific insertion and deletion of uridine residues. RNA editing is essential for creating translatable open reading frames (ORFs). We are performing functional and biochemical characterization of the large, dynamic RNA-protein complex termed MRB1, which coordinates multiple aspects of the RNA editing process. A second focus is on regulating RNA stability and translational control in T. brucei, which constitute the major methods of gene regulation in this organism. We identified an RNA binding protein, DRBD18, that impacts the stabilities of hundreds of mRNAs. Our data support a model in which posttranslational modification of DRBD18 by arginine methylation acts as a switch to change DRBD18 from an mRNA destabilizer to an mRNA stabilizer by regulating specific protein-protein and protein-RNA interactions. We are testing this model in vitro and in vivo using reporter assays, in vivo protein-RNA cross-linking and protein-protein interaction assays. A third focus is on understanding the mechanisms by which protein arginine methylation modulates trypanosome biology. We performed a global proteomic analysis of the arginine methylome of T. brucei, identifying >1100 methylproteins spanning most cellular compartments and a wide array of functional classes. We are now analyzing novel mechanisms of protein arginine methyltransferase regulation and defining the physiological and molecular functions of arginine methylmarks on selected proteins. I foster a collaborative and flexible laboratory environment, and I encourage my students to explore the research topics that interest them.
Cardiopulmonary physiology; Cytoskeleton and cell motility; Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular and Cellular Biology; Molecular Basis of Disease; Signal Transduction
My research interests center on mechanical and electrical biophysics, from molecules to organs, and the development of new tools. And, in recent years I worked in transitional science; bringing basic science to the clinic and to industry. My basic research interests are on cell mechanics and the mechanisms by which mechanical forces are transduced into messages such as voltage and chemicals such as ATP and Ca2+. I discovered mechanosensitive ion channels in 1983. My methodology has included patch clamp, high resolution bright field light microscopy, low light fluorescence microscopy, high speed digital imaging, TIRF, digital image analysis, high voltage EM with tomography, Atomic Force Microscopy, molecular biology, natural product and recombinant protein biochemistry, NMR and microfabrication and microfluidics. We discovered the only known specific inhibitor of mechanosensitive ion channels and uncovered its remarkable mode action by using a combination of electrophysiology and chiral chemistry. We have demonstrated potential clinical applications of the peptide for cardiac arrhythmias, oncology, muscular dystrophy, and incontinence. We have developed many scientific tools. Recently we developed a sensor chip to measure cell volume in real time, and that is now entering production with Reichert Instruments of Buffalo. We also have an Small Business Innovation Research contract to develop a microfluidic, bipolar, temperature jump chip with ALA Scientific and developed a microfabricated Atomic Force Microscopy probe that is an order of magnitude faster and more stable than any commercial probes. We have made probe operable with two independent degrees of freedom on a standard Atomic Force Microscopy. This permits us to remove all drift and coherent noise by using one axis to measure the substrate position and the other the sample position. These probes are being produced by a new company in Buffalo, kBtwist. We have used the Atomic Force Microscope combined with electrophysiology to study the dynamics of single voltage dependent ion channels. This technique provides a resolution of >0.01nm in a kHz bandwidth. I have developed other hardware including the first automated microelectrode puller, a micron sized thermometer and heater and a high speed pressure servo. Some of these devices have been patented by the University of Buffalo and some are in current production. To analyze the reaction kinetics of single molecules, we developed and made publicly available (www.qub.buffalo.edu) a complete software package for Windows that does data acquisition and Markov likelihood analysis. The development was funded by the National Science Foundation, National Institutes of Health and Keck over the last fifteen years, and has been applied to ion channels, molecular motors and the even the sleep patterns of mice. We have taught at UB hands-on course to use the software, and the course was attended by an international group of academic scientists and students, government and industry.
Cell growth, differentiation and development; DNA Replication, Recombination and Repair; Gene Expression; Molecular and Cellular Biology; Proteins and metalloenzymes; Signal Transduction; Transcription and Translation
The main goal of my research group is to understand the role of N-terminal methylation on human development and disease. I identified the first eukaryotic N-terminal methyltransferases, NRMT1 and NRMT2, and am now working to identify how these enzymes and this new type of methylation affect cancer development and ageing. Our laboratory has shown that NRMT1 functions as a tumor suppressor in mammary glands, and its loss sensitizes breast cancer cells to DNA damaging chemotherapeutics. We have also created the first NRMT1 knockout mouse and shown it to have developmental defects, as well as, exhibit phenotypes of premature ageing. Currently, we are working to understand the exact biochemical pathways that lead from loss of N-terminal methylation to these phenotypes. We are also studying how post-translational modifications on the N-terminus of proteins may interact and dictate protein function, similar to the post-translational modifications found on histone tails.
Genomics and proteomics; Molecular and Cellular Biology; Regulation of metabolism; Toxicology and Xenobiotics
Dr. David Shubert has been at the University at Buffalo since 2006. He received is B.S in Pharmacy from Duquesne University and a Ph.D from the University at Buffalo. His research interests include the mechanism by which environmental chemicals initiate and promote cancer. He is the Assistant Dean for Biomedical Undergraduate Education and teaches pharmacology, toxicology and cardiovascular physiology. Dr. Shubert accepts undergraduate students interested in pursuing research in his areas of interest. He is an active member of the Society of Toxciology.
Genomics and proteomics; Molecular and Cellular Biology; Gene Expression
My laboratory is interested in understanding the transcriptional control mechanisms that dictate epithelial cell development and differentiation. Specifically, we seek to understand the functional role of a p53-family member, p63 and Ets family of proteins in epithelial cells such as those of the skin and mammary glands. Towards this end, we have developed and characterized transgenic mice in which the normal expression pattern of these crucial factors is altered by both gain-of-function (Tet-inducible transgenic system) and loss-of-function (knockout) experiments. Our broad objectives are to elucidate the molecular mechanism by which transcription factors such as p63 and Ets proteins regulate their target genes and how such regulation of specific pathways dictate cell fate, development and differentiation. We utilize broad biochemical and genetic approaches, cell culture systems and state of the art genome-wide interrogation techniques to answer questions about differentiation of progenitor/stem populations and to examine molecular consequences of altered expression of transcription factors. These studies will not only help better understand the normal physiological processes but also lead to novel mechanistic insights into the pathophysiology of wide range of disease including cancer.
Cell growth, differentiation and development; Gene Expression; Molecular and Cellular Biology; Neurobiology; Signal Transduction
The long term mission of my research has been to understand developmental and regenerative processes within the mammalian CNS. Towards these goals I have employed stereological and microscopic imaging techniques, stem cell cultures and in vivo models to analyze brain development, regenerative capacity, etiology of neurodevelopmental and neurodegenerative diseases. I have established a quantitative Neuroanatomy Stereology laboratory within a multi-disciplinary Molecular and Structural Neurobiology and Gene Therapy Program. Current projects: Developmental disorder- Schizophrenia The studies that I have been engaged in the last several years have addressed fundamental aspects of organismal development, their pathological disruptions and their targeting for regenerative medicine. With the advent of multicellular organisms, mechanisms emerged that imposed new controls which limited the natural propensity of organisms composed of single cells to proliferate, and to invade new locales, which ultimately results in the formation of tissues and organs. How such an immense task is accomplished has been largely unknown. Our collaborative studies have revealed a pan-ontogenic gene mechanism, Integrative Nuclear Fibroblast Growth Factor Receptor 1 (FGFR1) Signaling (INFS), which mediates global gene programing through the nuclear form of the FGFR1 receptor (nFGFR1) and its partner CREB Binding Protein, so as to assimilate signals from diverse signaling pathways. My work, which has contributed to these findings, has been focused on the role of INFS in cellular development. I have shown that INFS is central to the development of neural cells and that pluripotent ESC and multipotent NPCs can be programmed to exit from their cycles of self-renewal, and to undergo neuronal differentiation simply by transfecting a single protein, nFGFR1. Using viral and novel, nanotechnology based gene transfers, I have demonstrated that it is possible to reactivate developmental neurogenesis in adult brain by overexpressing nFGFR1 in brain stem/progenitor cells. We have shown that similar effects can be produced by small molecules that activate the INFS. These findings may revolutionize treatments of abnormal brain development, injury and neurodegenerative diseases by targeting INFS to reactivate brain neurogenesis. Schizophrenia (SZ) has been linked to the abnormal development of multiple neuronal systems, and to changes in genes within diverse ontogenic networks. Genetic studies have established a link between FGFs and nFGFR1 with these networks and SZ. nFGFR1 integrates signals from diverse SZ linked genes (>200 identified) and pathways[2-6] and controls developmental gene networks. By manipulating nFGFR1 function in the brain of transgenic mice I have established a model that mimics important characteristics of human schizophrenia: including its neurodevelopmental origin, the hypoplasia of DA neurons, increased numbers of immature neurons in cortex and hippocampus, disruption of brain cortical layers and connections, a delayed onset of behavioral symptoms, deficits across multiple domains of the disorder, and their correction by typical and atypical antipsychotics[6, 7]. To understand how SZ affects neural development, I have begun to generate induced pluripotent stem cells (iPSCs) using fibroblast of SZ patients with different genetic backgrounds. In my studies I employ 3-dimensional cultures of iPSCs, co-developmental grafting of the iPSCs neural progeny into murine brain, FISH (Fluorescent In Situ Hybridization), gene transfer and quantitative stereological analyses. I am testing how genomic dysregulation affects the developmental potential of schizophrenia NPCs (formation of 3D cortical organoids, in vivo development of grafted iPSCs) which may be normalized by correcting nFGFR1 and miRNA functions. In summary, my studies are aimed to develop to new treatments for Schizophrenia and other neurodevelopmental disorders including potential preventive therapies. Effect of maternal diet and metabolic deficits on brain development (collaboration with Dr. Mulchand Patel, Department of Biochemistry, UB) Approximately 36% of the adults in the US are classified as obese. Available evidence from epidemiological and animal studies indicate that altered nutritional experiences early in life can affect the development of obesity and associated metabolic diseases in adulthood and subsequently in the offspring of these people. Furthermore, there is an increased risk for mental health disorders that is associated with these conditions. Our studies show that an altered maternal environment in female rats produced by consuming a high fat (HF) or high sugar diet (HS) negatively impacts the development of brain stem cells and fetal brain circuitry in the offspring[8, 9]. Increased numbers of immature, underdeveloped neurons are found in the hypothalamus, which controls feeding behavior. Similar changes are found in areas of the cerebral cortex involved in other diverse behavioral functions. These changes reveal an alarming predisposition for neurodevelopmental abnormalities in the offspring of obese female rats. Blast induced brain injury and regeneration (collaboration with Dr. Richard Salvi, Department of Communicative Disorders and Sciences, UB) Sound blast induced brain injury is a major concern in military exposure to excessive noise. In mice exposed to the sound blast we found marked loss of myelinated fibers and neuronal apoptosis in brain cortex. These degenerative changes were accompanied by increased proliferation of brain neural progenitor cells in the subventricular zone of the lateral ventricles. Immunohistochemical and stereological analyses reveal that these initial changes are followed by the gradual reappearance of myelinated cortical fibers. This is accompanied by increased proliferation of oligodendrocytic progenitors. I found that these progenitors also differentiate to mature oligodendrocytes in brain cortex. Our findings show that the blast-induced activation of the brain neural stem/progenitor cells generates predominantly new oligodendrocytes. The capacity of these new cells to myelinate damaged and regenerating neurons will be addressed in my planned future investigation.
Bioinformatics; Cell growth, differentiation and development; Gene Expression; Gene therapy; Genome Integrity; Genomics and proteomics; Molecular Basis of Disease; Molecular and Cellular Biology; Neurobiology; Signal Transduction; Stem Cells; Transcription and Translation
The long term mission of our laboratory, which I co-direct with Dr. Ewa Stachowiak, is to understand the principles governing molecular control of neural development, the implications for developmental- and aging-related diseases and the wide ranging effects on brain functions including behavior. The main achievement of our program has been the discovery of “Integrative Nuclear FGFR1 Signaling”, INFS a universal signaling mechanism which plays a novel integral role in cell development and complements other universal mechanisms such as mitotic cycle and pluripotency .Based on these revolutionary findings we have formulated a new theory called “Feed-Forward End-Gate Signaling” that explains how epigenetic factors either extracellular like neurotransmitters, hormonal or growth factors or intracellular signaling pathways control developmental gene programs and cellular development. This discovery is a product of our twenty-year multidisciplinary research that has been reported in several peer-reviewed papers in major journals including Proc. Natl. Acad. of Science (USA), Integrative Biology, Molecular Biology of the Cell, Journal of Cell Biology, Journal of Biological Chemistry, Journal of Physical Chemistry (etc.). In addition, we have applied this theory to analyze the etiology of neurodevelopmental /neurodegenerative disorders, and cancer in order to utilize it in new potential therapies. Towards these goals we have employed new technologies for an in vivo gene transfer, developed new transgenic mouse models for Schizophrenia and Parkinson-like diseases and established an interdisciplinary Molecular and Structural Neurobiology and Gene Therapy Program which has o engaged researchers from the different UB departments, other universities in the US as well as foreign institutions including Hannover Medical School (Germany), Gdansk Medical University, and Polish Academy of Science. Detailed research activities and future goals of our research program: 1. Molecular mechanisms controlling development of neural stem and related cells. In studying molecular mechanisms controlling development of neural stem and related cells we have established a novel universal signal transduction mechanism -Feed-Forward-And Gate network module that effects the differentiation of stem cells and neural progenitor cells. In the center of this module is the new gene-controlling mechanism "Integrative Nuclear Fibroblast Growth Factor Receptor-1 (FGFR1) Signaling" (INFS), which integrates diverse epigenetic signals and controls cell progression through ontogenic stages of proliferation, growth, and differentiation. We have shown that, Fibroblast Growth Factor Receptor-1 (FGFR1) a protein previously thought to be exclusively involved with transmembrane FGF signaling, resides in multiple subcellular compartments and is a multifactorial molecule that interacts with diverse cellular proteins In INFS, newly synthesized FGFR1 is released from the endoplasmic reticulum and translocates to the nucleus. In the nucleus, FGFR1 associates with nuclear matrix-attached centers of RNA transcription, interacts directly with transcriptional coactivators and kinases, activates transcription machinery and stimulates chromatin remodeling conducive of elevated gene activities. Our biophotonic experiments revealed that the gene activation by nuclear FGFR1 involves conversion of the immobile matrix-bound and the fast kinetic nucleoplasmic R1 into a slow kinetic chromatin binding population This conversion occurs through FGFR1’s interaction with the CBP and other nuclear proteins. The studies support a novel general mechanism in which gene activation is governed by FGFR1 protein movement and collisions with other proteins and nuclear structures. The INFS governs expression of developmentally regulated genes and plays a key role in the transition of proliferating neural stem cells into differentiating neurons development of glial cells, and can force neoplastic medulloblastoma and neuroblastoma cells to exit the cell cycle and enter a differentiation pathway and thus provides a new target for anti-cancer therapies. In our in vitro studies we are using different types of stem cells cultures, protein biochemistry, biophotonics analyses of protein mobility and interactions [Fluorescence Recovery after Photobleaching (FRAP), Fluorescence Loss In Photobleaching (FLIP), and Fluorescence Resonance Energy Transfer (FRET)] and diverse transcription systems to further elucidate the molecular circuits that control neural development. 2. Analyses of neural stem cell developmental mechanisms in vivo by direct gene transfer into the mammalian nervous system. An understanding of the mechanisms that control the transition of neural stem/progenitor cells (NS/PC) into functional neurons could potentially be used to recruit endogenously-produced NS/PC for neuronal replacement in a variety of neurological diseases. Using DNA-silica based nanoplexes and viral vectors we have shown that neuronogenesis can be effectively reinstated in the adult brain by genes engineered to target the Integrative Nuclear FGF Receptor-1 Signaling (INFS) pathway. Thus, targeting the INFS in brain stem cells via gene transfers or pharmacological activation may be used to induce selective neuronal differentiation, providing potentially revolutionizing treatment strategies of a broad range of neurological disorders. 3. Studies of brain development and neurodevelopmental diseases using transgenic mouse models. Our laboratory is also interested in the abnormal brain development affecting dopamine and other neurotransmitter neurons and its link to psychiatric diseases, including schizophrenia. Changes in FGF and its receptors FGFR1 have been found in the brains of schizophrenia and bipolar patients suggesting that impaired FGF signaling could underlie abnormal brain development and function associated with these disorders. Furthermore the INFS mechanism, integrates several pathways in which the schizophrenia-linked mutations have been reported. To test this hypothesis we engineered a new transgenic mouse model which results from hypoplastic development of DA neurons induced by a tyrosine kinase-deleted dominant negative mutant FGFR1(TK-) expressed in dopamine neurons. The structure and function of the brain’s DA neurons, serotonin neurons and other neuronal systems including cortical and hippocampal neurons are altered in TK- mice in a manner similar to that reported in patients with schizophrenia. Moreover, TK- mice express behavioral deficits that model schizophrenia-like positive symptoms (impaired sensory gaiting), negative symptoms (e.g. low social motivation), and impaired cognition ameliorated by typical or atypical antipsychotics. Supported by the grants from the pharmaceutical industry we are investigating new potential targets for anti-psychotic therapies using our preclinical FGFR1(TK-) transgenic model. Our future goals include in vivo gene therapy to verify whether neurodevelopmental pathologies may be reversed by targeting endogenous brain stem cells. Together with the other researchers of the SUNY Buffalo we have established Western New York Stem Cells Analysis Center in 2010 which includes Stem Cell Grafting and in vivo Analysis core which I direct. Together with Dr. E. Tzanakakis (UB Bioengineering Department) we have written book “ Stem cells- From Mechanisms to Technologies’ (World Scientific Publishing, 2011). Educational Activities and Teaching: I have participated together with the members of our neuroscience community in developing a new Graduate Program in Neuroscience at the SUNY, Buffalo. I am teaching neuroanatomy courses for dental students (ANA811) and for graduate students (NRS524). At present I participate in team-taught graduate courses in Neuroscience and Developmental Neuroscience (NRS 520, 521 and NRS 524). I am serving as a mentor for several undergraduate, graduate (masters and doctoral students) and postdoctoral fellows in the Neuroscience Program, Anatomy and Cell Biology Program and in the IGERT program in the Departments of Chemistry and Engineering. Additionally to mentoring master and Ph.D. students at the UB, I have helped to train graduate students in the University of Camerino (Italy) and Hannover Medical School (Germany). The works of our graduate students have been described in several publications.
DNA Replication, Recombination and Repair; Genome Integrity; Molecular and Cellular Biology; Molecular genetics; Protein Function and Structure
In my laboratory, we are interested in the general problem of maintaining genome stability. To this end, we focus on two distinct aspects of genome stability: 1) the roles of mismatch (MMR) proteins in multiple pathways for DNA repair and 2) the manner in which regulation of dNTP pools, through the regulation of ribonucleotide reductase (RNR) activity, impacts genome integrity. 1) MMR proteins recognize many different types of DNA lesions and then target the lesion for the appropriate repair pathway. We are interested in the mechanism(s) by which recognition of a lesion is translated into the appropriate DNA repair pathway, using the yeast Saccharomyces cerevisiae as a model system. Is it through differential protein-nucleic acid or protein-protein interactions? To address these questions as well as the regulation of DNA repair pathway selection, we use a combination of genetic, biochemical and biophysical approaches. 2) RNR activity modulates the level of dNTPs that are available in a cell at a given time. Higher levels of dNTPs lead to higher mutation rates. We are interested in the various ways in which misregulated dNTP pools might affect cellular metabolism and affect the stability of the genome.
DNA Replication, Recombination and Repair; Gene Expression; Genome Integrity; Microbiology; Molecular and Cellular Biology; Protein Function and Structure; Signal Transduction
We are interested in developing an integrated mechanistic view of how organisms coordinate the actions of their DNA replication machinery with those of other cellular factors involved in DNA repair and damage tolerance. Failure to properly coordinate these functions leads to mutations, genome instability, and in extreme cases, cell death. We utilize a combination of biochemical, biophysical, and genetic approaches to investigate the molecular mechanisms of DNA replication, DNA repair, and error-prone DNA damage tolerance functions in Escherichia coli. The primary mechanism for damage tolerance involves direct bypass of damaged bases in the DNA. This process is inherently error-prone, and is the basis for most mutations. Current efforts are focused on understanding the mechanisms by which the actions of high fidelity and error-prone lesion bypass DNA polymerases are coordinated with each other, as well as other proteins involved in DNA metabolism. Our goal in this work is to develop methods that enable us to control the fidelity of DNA repair for therapeutic gain. We are also interested in understanding the mechanisms that contribute to DNA mutagenesis in the opportunistic human pathogen, P. aeruginosa. P. aeruginosa is a particular problem for individuals afflicted with cystic fibrosis. Persistent colonization of cystic fibrosis airways with P. aeruginosa serves as a major source of morbidity and mortality for these patients. The ability of P. aeruginosa to persist in the airways relies in part on its ability to adapt to the continuously changing environment within the diseased airways. We are particularly interested in determining the contribution of mutagenesis and DNA repair to adaptive mutations that contribute to clonal expansion and pathoadaptation of P. aeruginosa during colonization of cystic fibrosis airways.
Cell growth, differentiation and development; Membrane Transport (Ion Transport); Molecular and Cellular Biology; Signal Transduction; Inherited Metabolic Disorders; RNA
Regulation of Kidney Epithelial Cell Growth, Transport and Differentiation Our laboratory is investigating the molecular mechanisms by which hormones, growth factors and extracellular matrix proteins regulate kidney tubule epithelial cell growth and functional differentiation in vitro. An established canine kidney epithelial cell line, MDCK, and isolated "mutants" are currently being utilized to examine the actions of growth regulatory on the expression of several proteins including the Na+, K+-ATPase and laminin, a glycoprotein in the extracellular matrix. The effects of novel growth regulatory factors on the expression of proteins involved in gluconeogenesis, membrane transport, renal disease and growth control in primary renal cell cultures are being examined. Primary kidney epithelial cells differentiate into nephrons in a reconstituted extracellular matrix proteins is the subject of study.
Infectious Disease; Microbiology; Microbial Pathogenesis; Molecular and Cellular Biology; Gene Expression; Transcription and Translation; Protein Function and Structure; RNA; Eukaryotic Pathogenesis
In my laboratory, we use molecular biological and biochemical approaches to study Trypanosoma brucei, the causative agent of African sleeping sickness, and Trypanosoma cruzi, which causes Chagas disease in South and Central America. Treatment for these diseases is severely limited due to increasing drug resistance and lack of available drugs. The goal of our work is to discover and exploit critical events that occur in the parasite life cycle that may be used to prevent growth or transmission of the parasite. The major project in my laboratory examines the ribosome, the complex molecular machine that drives protein synthesis. While many features of the ribosome and its assembly pathway are conserved in the parasites we study, we have identified features that are very different from the human host. Our laboratory discovered a pair of trypanosome-specific RNA binding proteins, P34 and P37, that are part of a unique preribosomal complex that is essential for ribosomal biogenesis and survival of trypanosomes. This may suggest that the interaction of these proteins with other components of the ribosomal assembly pathway can be developed as targets for chemotherapy. We are developing a high-throughput screen for small molecules that disrupt the complex in trypanosomes and do not harm the human host. My team and I also collaborate with Dr. Joachim Frank at Columbia University on a project to examine the structure of the ribosome and intermediates in the pathway of assembly using cryo-electron microscopy (cryo-EM). These experiments will provide important information about the unique features of the structure and function of the trypanosome ribosome and further our discovery of potential drug targets. In addition, we continue in a long-standing collaboration with Dr. Beatriz Garat at the Universidad de la Républica in Uruguay, examining both DNA and RNA binding proteins which regulate gene expression in Trypanosoma cruzi. The balance of graduate, undergraduate and medical students and postdoctoral researchers I mentor changes from year to year, though the international quality I strive to maintain has distinguished my laboratory for years: I enjoy having students from around the world as part of my research team. I am the course director for, and lecture in Critical Analysis and Eukaryotic Pathogens. I am also the course director for Eukaryotic Gene Expression and the co-course director for Molecular Parasitology.
Cell growth, differentiation and development; Microbiology; Molecular Basis of Disease; Molecular and Cellular Biology; Regulation of metabolism; Signal Transduction; Toxicology and Xenobiotics; Vitamins and Trace Nutrient
Dr. Willsky’s research focuses on the role of oxovanadium compounds in cellular metabolism. V is a trace metal believed to be required for growth. Oral administration of oxovanadium compounds alleviates the symptoms of Diabetes in animal models and humans. The techniques of genetics, microbiology, molecular biology, biochemistry, pharmacology, magnetic resonance spectroscopy, and cell physiology are used. The diabetes-altered gene expression of genes involved in lipid metabolism, oxidative stress and signal transduction is returned to normal by V treatment of rats with STZ-induced diabetes, as demonstrated using DNA microarrays. Inhibition of tyrosine protein phosphatases is believed to be a major cause of the insulin-like effects of V. Our results implicate the interaction of V with cellular oxidation-reduction reactions as being important in the anti-diabetic mechanism of V complexes. A new project in the lab studies the mode of action of medicinal plant mixtures used by the native healers of Peru.
Neurodegenerative disorders; Pathophysiology; Cytoskeleton and cell motility; Molecular Basis of Disease; Molecular and Cellular Biology; Neurobiology; Neuropharmacology; Signal Transduction
Synaptic Mechanisms of Mental Health and Disorders Our research goal is to understand the synaptic action of various neuromodulators that are linked to mental health and illness, including dopamine, stress hormones, and disease susceptibility genes. Specifically, we try to understand how these neuromodulators regulate glutamatergic and GABAergic transmission in prefrontal cortex (PFC), which is important for emotional and cognitive control under normal conditions. We also try to understand how the aberrant action of neuromodulators under pathological conditions leads to dysregulation of synaptic transmission in PFC, which is commonly implicated in brain disorders. The major techniques used in our studies include: • whole-cell patch-clamp recordings of synaptic currents, • viral-based in vivo gene transfer, • biochemical and immunocytochemical detection of synaptic proteins, • molecular analysis of genetic and epigenetic alterations, • chemogenetic manipulation of neuronal circuits, • behavioral assays. By integrating the multidisciplinary approaches, we have been investigating the unique and convergent actions of neuromodulators on postsynaptic glutamate and GABAA receptors, and their contributions to the pathogenesis of a variety of mental disorders, including ADHD, autism, schizophrenia, depression, PTSD and Alzheimer‘s disease.
Ophthalmology; Retina; Apoptosis and cell death; Gene Expression; Gene therapy; Molecular Basis of Disease; Molecular and Cellular Biology; Neurobiology; Protein Folding; Regulation of metabolism; Signal Transduction; Vision science
The research in my lab has focused on two main areas: 1). molecular mechanisms of inflammation, angiogenesis, vascular and neuronal degeneration in retinal diseases; 2). potential roles of angiogenic inhibitors in obesity, insulin resistance and diabetes. The first line of research centers on gene regulation and signal transduction pathways underlying the neurovascular injury in diabetic retinopathy, retinopathy of prematurity and age-related macular degeneration. In recent years, we are focusing our efforts on the function and mechanism of the UPR signaling in normal and diseased retinal cells. The latter one combines basic and clinical research to study biomarkers and mechanism of type 2 diabetes. 1. ER stress and the UPR signaling in retinal neurovascular injury and diabetic retinopathy. The endoplasmic reticulum (ER) is the primary site for protein synthesis and folding. Failure of this machinery to fold newly synthesized proteins presents unique dangers to the cell and is termed “ER stress.” In response to the stress, cells have evolved an intricate set of signaling pathways named the unfolded protein response (UPR) to restore the ER homeostasis. In addition, the UPR is known to regulates many genes involved in important physiological processes to modulate cell activity and cell fate. The project in my laboratory is aimed to understand the role of ER stress and the UPR in retinal vascular endothelial cell dysfunction and neuronal degeneration in diabetic retinopathy. Our previous work has implicated several key UPR branches such as IRE-XBP1 and ATF4-CHOP in retinal inflammation and vasculopathy in diabetes. Currently, we are employing integrated genetic tools and animal models to study the function of UPR genes in the retina and to dicepher the molecular links between the UPR signaling and inflammatory pathways in retinal cells. Findings from these studies are anticipated to identify novel therapeutic targets and develop new treatments for diabetic retinopathy. 2. Mechanisms and potential therapies for RPE death in age-related macular degeneration. The retinal pigment epithelium (RPE) plays an essential role in maintaining the normal structure and function of photoreceptors. RPE dysfunction and cell death is a hallmark pathological characteristic of age-related macular degeneration (AMD), a disease that accounts for the majority of vision impairment in the elderly. Using transgenic mouse models, we discovered that the transcription factor XBP1 is a critical regulator of oxidative stress and cell survival in RPE cells. Genetic depletion or inhibition of XBP1 sensitizes the RPE to stress resulting in cell death. Our ongoing studies focus on identifying the target genes of XBP1 in RPE cells through which the protein regulates cell survival. We are also investigating if these proteins could offer potential salutary effects to protect RPE cells from oxidative injury and degeneration in disease conditions such as AMD. 3. Roles and mechanisms of angiogenic/anti-angiogenic factors in obesity, insulin resistance and diabetes. Obesity, insulin resistance and Type 2 diabetes are clustered as the most important metabolic disorders, substantially increasing morbidity and impairing quality of life. Excess body fat mass, particularly visceral fat, leads to dysregulation of adipokines (proteins secreted from fat cells), resulting in higher risk of cardiovascular diseases. Our recent findings indicate that angiogenic/anti-angiogenic factors are associated with obesity, diabetes and diabetic complications. For example, pigment epithelium-derived factor (PEDF), a major angiogenic inhibitor, is an active player in adipose tissue formation, insulin resistance and vascular function. In the future, we hope to futher understand the functions and mechanisms of these proteins in lipid metabolism and adiposity. In collaboration with a number of clinical investigators, we are exploring the physiological application of these factors as novel biomarkers and therapeutic targets in the diagnosis and treatment of diabetes, metabolic disorders and peripheral vascular diseases.