MTD-1, a touch-cell-specific membrane protein with a subtle effect on touch sensitivity

We have used representational difference analysis (RDA) applied to cDNA to isolate transcripts regulated by MEC-3, a transcription factor needed for the differentiation of the six touch receptor neurons in Caenorhabditis elegans. Six percent of 595 cDNAs isolated by cDNA RDA were mec-3-dependent. These cDNAs represented mRNA from two previously known genes, mec-18 and mec-7, and one new gene, mtd-1 (mec-three-dependent). mtd-1 encodes a novel transmembrane protein that is exclusively expressed in the six touch cells throughout development. mtd-1 loss results in a subtle defect in the touch receptor neurons. Neither mtd-1 RNAi nor a putative mtd-1 loss-of-function mutation resulted in touch insensitivity, but both enhanced the touch insensitivity of mec-6(u247), a temperature sensitive allele, at the permissive temperature.