Control of Cellular Excitability by KCNQ-Like Potassium Channels in C. Elegans

Washington University School Of Medicine, Saint Louis MO

Investigators

Abstract

"Control of Cellular Excitability by KCNQ-like Potassium Channels in C. elegans." Potassium channels are selectively permeable membrane proteins critical for shaping the normal electrical properties of neurons, muscles and epithelial cells. The availability of whole genomic sequences from a range of organisms has revealed a complete set of evolutionarily conserved genes underlying most potassium channel diversity. The in vivo functions of one particular conserved class of potassium channel genes, forming the KCNQ gene family, will be studied in the model organism Caenorhabditis elegans through a combination of genetic, electrophysiological and behavioral techniques. This gene family is important because members of this family likely form M-type potassium channels. These channels are active at subthreshold voltages and modulated by activation of neurohormonal receptors, and thus may act as long-term determinants of basal excitability. In addition, human members of this gene family are responsible for diverse hereditary diseases. Three KCNQ-like genes are found in the C. elegans genome (kqt-1, kqt -2, and kqt-3). The tissue expression and cellular distribution patterns of these genes will be examined using transgenic reporter constructs fusing regulatory sequences of each gene with green fluorescent protein (GFP) and by developing gene-specific antibodies. The functional properties of channels encoded by these genes will be characterized by voltage-clamp recordings from Xenopus oocytes expressing each gene, and by in situ recordings from selected C. elegans cells. Genetic strains will be created that reduce or eliminate the function of each kqt gene. Resulting mutant phenotypes will be characterized by electrophysiological and behavioral assays. Preliminary results suggest specific roles for these channels in regulating the rhythmicity of pharyngeal muscle contractions and the dynamics of intracellular calcium release in intestinal cells. These studies may reveal conserved in vivo functions for KCNQ potassium channels, and form the basis for forward genetic screens to identify novel genes that regulate these channels.