Hill-Harfe, Katherine, Alam, Tashrique, Choe, Keith, Leung, Chi, Harfe, Brian, Wang, Ying
[
International Worm Meeting,
2011]
Calcium-activated chloride channels (CaCCs) function in transmitter release from photoreceptors, excitability in neuron and myocyte membranes, sensory signal transduction, and epithelial membrane transport. Despite their importance, the molecular identity of CaCCs remained unknown until the TMEM16 transmembrane protein family was recently identified as CaCCs. Two current goals of the field are to characterize the physiological functions of TMEM16 proteins and define the molecular mechanisms that regulate channel activity. There are 10 TMEM16 family members in mammals with overlapping expression and potentially redundant functions that can hinder genetic and physiological analysis; there are only two TMEM16 family members in C. elegans, F56A8.1 and Y57G11C.37. To establish a genetic model for TMEM16 function and regulation, we have begun to characterize the expression and function of both C. elegans homologues. GFP reporter analysis demonstrates that the F56A8.1 promoter is active in amphid and phasmid neurons and suggest that the protein is enriched in sensory cilia. The Y57G11C.37 promoter is active in the spermatheca, lateral mechanosensory neurons, ventral nerve cord, and a few neurons in the head. Y57G11C.37::GFP fusion proteins are in or near the basal membrane of the spermatheca and in punctate structures with the appearance of synapses in the ventral nerve cord. F56A8.1(RNAi) in a strain of worms sensitized to neuronal RNAi (Calixto et al., 2010 Nat. Methods 7(7):554) reduces osmotic avoidance behaviors suggesting a role in sensory perception or signal transduction. Y57G11C.37(RNAi) in the same strain of worm reduces motility suggesting that the gene plays a role in neuromuscular function. We are currently generating null alleles for both TMEM16 genes in C. elegans and designing genetic screens to identify pathway components.