NOMPC is likely a key component of Drosophila mechanotransduction channels

Mechanotransduction is the basis of several sensory modalities, including touch, hearing, proprioception and gravity sensation. Despite its importance to sensory processing and behavior, the molecular mechanisms underlying mechanotransduction remain to be fully understood. In particular, the identity of the ion channels serving mechanotransduction is still unknown in many species. Drosophila melanogaster nompC (no mechanoreceptor potential C) has been shown to be essential for mechanotransduction in flies, yet there is no direct evidence demonstrating that NOMPC is indeed a mechanotransducing ion channel in Drosophila. To dissect the functional roles of NOMPC in mechanotransduction, we found that NOMPC-dependent transient adapting mechanoreceptor current (MRC) in the external bristle sensory organ was also chloride dependent. However, this chloride-dependent current was not necessary for spike generation. Furthermore, ectopic expression of wild-type NOMPC conferred mechanosensitivity on the interneurons in the antennal lobe (AL) and cation-mediated inward mechanocurrent was recorded, while a point mutation in the putative selective filter region of NOMPC failed to produce the mechanocurrent in the AL interneurons. These functional studies imply that NOMPC is likely to be a crucial component of mechanotransducers that accounts for mechanotransductions in mechanosensory neurons of Drosophila.