title: The DEG/ENaC protein MEC-10 regulates the transduction channel complex in Caenorhabditis elegans touch receptor neurons.
abstract: Gentle touch sensation in Caenorhabditis elegans is mediated by the MEC-4/MEC-10 channel complex, which is expressed exclusively in six touch receptor neurons (TRNs). The complex contains two pore-forming subunits, MEC-4 and MEC-10, as well as the accessory subunits MEC-2, MEC-6, and UNC-24. MEC-4 is essential for channel function, but beyond its role as a pore-forming subunit, the functional contribution of MEC-10 to the channel complex and to touch sensation is unclear. We addressed this question using behavioral assays, in vivo electrophysiological recordings from TRNs, and heterologous expression of mutant MEC-10 isoforms. Animals with a deletion in mec-10 showed only a partial loss of touch sensitivity and a modest decrease in the size of the mechanoreceptor current (MRC). In contrast, five previously identified mec-10 alleles acted as recessive gain-of-function alleles that resulted in complete touch insensitivity. Each of these alleles produced a substantial decrease in MRC size and a shift in the reversal potential in vivo. The latter finding indicates that these mec-10 mutations alter the ionic selectivity of the transduction channel in vivo. All mec-10 mutant animals had properly localized channel complexes, indicating that the loss of MRCs was not attributable to a dramatic mislocalization of transduction channels. Finally, electrophysiological examination of heterologously expressed complexes suggests that mutant MEC-10 proteins may affect channel current via MEC-2.
authors: Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
authors: Jóhanna
authors: J
authors: Arnadóttir
authors: Robert
authors: R
authors: O'Hagan
authors: Yushu
authors: Y
authors: Chen
authors: Miriam B
authors: MB
authors: Goodman
authors: Martin
authors: M
authors: Chalfie
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics; D047468:Immunoprecipitation / Q000379:methods; D066298:In Vitro Techniques; D040542:Mechanotransduction, Cellular / Q000235:genetics / Q000502:physiology*; D008564:Membrane Potentials / Q000235:genetics / Q000502:physiology; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008845:Microinjections / Q000379:methods; D020125:Mutation, Missense / Q000235:genetics; D009865:Oocytes; D010812:Physical Stimulation / Q000379:methods; D017354:Point Mutation / Q000235:genetics; D034622:RNA Interference / Q000502:physiology; D011984:Sensory Receptor Cells / Q000378:metabolism*; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism; D014110:Touch / Q000235:genetics*
chemical_list: D029742:Caenorhabditis elegans Proteins; C094927:Deg-1 protein, C elegans; C096705:MEC-2 protein, C elegans; D008565:Membrane Proteins; D015222:Sodium Channels; C085942:MEC-10 protein, C elegans