Department of Physiology and Biophysics
Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular and Cellular Biology; Molecular Basis of Disease; 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.