Mec-6 may encode a degenerin Charles Ma, Guoquiang Gu and Marty Chalfie. Dept. of Biological Sciences, Columbia University, NY, NY 10027 The gene
mec-6 is needed for the function of a set of touch receptor neurons (ALMs, PLMs, AVM and PVM). In addition, its was found that recessive mutations in
mec-6 are able to suppress neuronal degenerations caused by dominant mutations in the genes
deg-1,
mec-4, and
mec-10. These three genes all belong to a family of genes encoding degenerin protein. Based on the phenotype of the dominant mutations and the similarities of the degenerins to the components of the vertebrate amiloride-sensitive sodium channel, it is likely that the degenerins form membrane channels that can mutate to cause neuronal degenerations. One attractive model is that MEC-4 and MEC-10 help to form the mechanosensory channel in the touch receptor cells. In rat, the amiloride-sensitive sodium channel is made of three different degenerin-like subunits. We have investigated whether a third degenerin subunit is found in the touch cells. The best candidate for such a component is the
mec-6 protein product. We have found an apparent degenerin homologue that maps to the
mec-6 region on chromosome 1. Using degenerative oligos that encode highly conserved regions of the degenerin gene family, we were able to PCR amplify a small fragment from the cosmid W01 A8 that shares sequence homology with the degenerins. In addition, we cloned a 1 .3kb genomic fragment that includes this region and found that this fragment detects a deletion in animals with the
mec-6(
u450) gamma-ray mutation. Several transcripts were detected on a northern blot using this genomic fragment as probe. We are testing whether these transcripts are absent in the
mec-6(
u450) animals. It seems likely that this degenerin is the
mec-6 gene.