Characterization of a TRPP complex and its interacting components acting in sex pheromone perception of male C. elegans

In nature, chemical communication between animals is important for species survival. Finding a mating partner in dioecious species is one of these survival strategies. Caenorhabditis remanei females produce a sex pheromone with long-range attractiveness for both C. remanei and C. elegans males. Using C. elegans as a model for studying this chemotactic behavior, two polycystin genes lov-1 and pkd-2, were shown to be required for sex pheromone sensation. These genes encode a transient receptor potential polycystin (TRPP) ion channel complex, which is localized to the ciliary structures implicated in sensation underlying both developmental and physiological processes. TRPP complex in human is important in kidney’s function, and their mutations are associated with autosomal dominant polycystic kidney disease (ADPKD). In mice, this protein complex is involved in determining left-right asymmetry during organogenesis. In C. elegans, the TRPP complex is localized to the ciliated endings of male-specific CEM neurons, which were previously shown to be required for sex pheromone chemotaxis through laser ablation and genetic analyses. In this study, I confined the acting site of PKD-2 to neuronal cilia in which odorants interact with their corresponding receptors. I also performed an electrophysiological assay to correlate the chemical stimuli with polycystin proteins in CEM neurons. These findings support the notion that the TRPP complex is activated by sex pheromone with intracellular signal relay. Importantly, these give us a glimpse into the chemosensory role of CEM neurons, the function of which remains elusive. In addition, I screened for additional mediators of polycystin signaling. Interestingly, atp-2 (ATP synthase subunit) was found to be acting in polycystin signaling to regulate sex pheromone chemotaxis. This ATP synthase subunit is co-localized with polycystin proteins to the neuronal ciliary compartment and is probably playing an unanticipated role to modulate C. elegans sexual behavior