Diverse regulation of sensory signaling by C. elegans nPKC-epsilon/eta TTX-4

Molecular and pharmacological studies in vitro suggest that protein kinase C (PKC) family members play important roles in intracellular signal transduction. Nevertheless, the in vivo roles of PKC are poorly understood. We show here that nPKC-epsilon/eta TTX-4 in the nematode Caenorhabditis elegans is required for the regulation of signal transduction in various sensory neurons for temperature, odor, taste, and high osmolality. Interestingly, the requirement for TTX-4 differs in different sensory neurons. In AFD thermosensory neurons, gain or loss of TTX-4 function inactivates or hyperactivates the neural activity, respectively, suggesting negative regulation of temperature sensation by TTX-4. In contrast, TTX-4 positively regulates the signal sensation of ASH nociceptive neurons. Moreover, in AWA and AWC olfactory neurons, TTX-4 plays a partially redundant role with another nPKC, TPA-1, to regulate olfactory signaling. These results suggest that C. elegans nPKCs regulate different sensory signaling in various sensory neurons. Thus, C. elegans provides an ideal model to reveal genetically novel components of nPKC-mediated molecular pathways in sensory signaling.