Research Associate Professor
Arrhythmias; Biomedical Imaging; Biophysical Modeling; Biophysics; Cardiopulmonary physiology; Cardiovascular Disease; Cytoskeleton and cell motility; Drug Design; Drug Design; Drug Development; Drug Transport; Electrophysiology; Image Processing and Analysis; Ion channel kinetics and structure; Membrane Biophysics; Membrane Proteins; Membrane Transport (Ion Transport); Molecular and Cellular Biology; Molecular Imaging Techniques; Muscle disease; Muscular Dystrophy; Preclinical Research; Protein Folding; Protein Function and Structure; Pulmonary Disease; Signal Transduction; Stem Cells
Since 1997 my research has focused on membrane mechanical signaling complexes and their regulation by the cytoskeleton. I have a particular interest in the regulation of ion channels by mechanical stress. These studies led to the seminal discovery of the small peptide GsMTx4 that inhibits these channels. Since its discovery 20 years ago, GsMTx4 is still the only known selective inhibitor of these channels. GsMTx4, and its analogs, have been patented by the University and are sold worldwide by multiple biochemical supply companies. It has been used in hundreds of studies to identify the role of mechanosensitive channels in normal physiology and pathophysiology. These channels are currently being intensely studied as a point of intervention for diseases with strong mechanical components like cancer, cardiovascular, pulmonary and inflammatory disorders.
My lab leverages imaging, genetics, molecular biology and peptide chemistry techniques to study mechanical stress and signaling in muscle and cartilage cells. We use single cells assays and develops model systems of higher order in vitro organoid structures.
Even with the discovery and cloning of Piezo mechanosensitive ion channels (the target of GsMTx4) there are currently no compounds with equal inhibitory potency. This likely reflects its nonconventional mechanism of action which was revealed in a study using the “mirror” enantiomeric form of GsMTx4 made of all D amino acids. GsMTx4-D has the same inhibitory activity as the native L-form, but because they are mirror structures, the peptide mechanism of action cannot be the standard lock-and-key with the receptor channel. From this finding emerged a new model for the mechanism of inhibition of many animal venom peptides, where membrane association is required prior to receptor interactions, which has aided in drug design and modeling. GsMTx4 follows this model, but is a special case, where the membrane association itself interferes with bilayer tension development – the energy source for Piezo channels. My lab subsequently demonstrated using charge mutant analogs of GsMTx4 that the depth of peptide penetration into the outer monolayer was tension dependent, creating a “mobile surface area reservoir” to buffer membrane surface tension. These peptide studies and my background in membrane mechanics have led to my current NIH funding to study fluorescent analogs of GsMTx4 that may prove useful as probes of cell membrane tension changes and biomarkers of cell membrane stress in vitro and in vivo.
As alluded to above, my most recent focus has been studying the transmission and regulation of stresses in cells. For this purpose, I helped develop the first genetically encoded FRET based optical force sensors called cpstFRET. These probes are grafted into host cytoskeletal proteins and, using only visible light, report mechanical stress less invasively than traditional methods. These probes are transforming the way cellular forces are measured and spatio-temporally distributed. I am using these probes to investigate cell differentiation in muscular dystrophy where the cause of pathology is the loss of cortical structural proteins that protect against mechanical stress. Studies in muscle cell differentiation are fertile ground for further development of optical force probes due to the high spatial and functional distinction between the different mechanical compartments. I have used CRISPR technology to generate muscle progenitor cell lines with optical force probes grafted into key cytoskeletal proteins representing the cell nucleus, the cell cortex, and internal elements involved in force generation. My lab is currently completing a study demonstrating the use of force probes to report mechanical stress on the cell nucleus during differentiation and stem cell self-renewal – two processes where external forces influence gene expression critical to muscle regeneration. This publication will form the basis for my NIH R01 submission to study forces involved in aberrant muscle regeneration.
My research into dystrophic myotube development and the Piezo1 mechanosensitive channel inhibitor GsMTx4 became the impetus for a collaboration with my colleagues to cofound the biotech company called Tonus Therapeutics. The primary goal of this company is to develop GsMTx4 into a therapy for treating muscular dystrophy, cardiomyopathy and inflammatory related pathology. Mechanosensitive channel signaling is an important arena for drug development since all pathology results in cell morphological and underlying cytoskeletal changes that dysregulate these channels. In my position as scientific and business officer, I am the lead in procuring funding for efficacy testing of the peptide in different disease models and for developing new targeted forms of GsMTx4 to reduce off-target effects. In this position, I secured funding to complete two studies showing GsMTx4 protects dystrophic muscle from force induced damage, and that GsMTx4 can be used to treat cardiac ischemic reperfusion injury. More recently I have secured new funding for GsMTx4 investigations to elucidate the mechanisms of long-term cardiomyopathy development and as a gene therapy adjuvant for treating muscular dystrophy. We are developing new targeted forms of GsMTx4 to treat osteo arthritis and other inflammatory disease. Tonus is supported and promoted by the University at Buffalo Technology Transfer department as a Buffalo generated biomedical business.