Mec3

MEC3 is a transcription factor found in the nematode Caenorhabditis elegans. The gene was first identified through genetic screens that isolated mutants with defective touch sensation. MEC3 is encoded by a single exon and produces a protein containing a canonical paired domain and a homeobox domain, typical of the DEC (dorsal-ventral patterning) family of homeodomain proteins. Sequence analysis shows high conservation of the homeodomain with other Caenorhabditis species, indicating a critical functional role. Functionally, MEC3 acts as a transcriptional regulator of mechanosensory channel genes, most notably mec-4 and mec-10, which encode subunits of a degenerin/epithelial sodium channel complex required for gentle touch reception. Loss-of-function mutations in mec-3 abolish expression of these channel subunits in touch receptor neurons and result in immobility to gentle mechanical stimuli. MEC3 also interacts genetically with other transcription factors, such as its paralog MEC-18, forming a transcriptional cascade that specifies the identity of the six touch receptor neurons. Despite extensive study in worms, orthologs of MEC3 have not been described in vertebrate genomes, suggesting lineage‑specific adaptation of mechanosensory regulatory mechanisms.