Genetic regulation of mec‐3 gene expression implicated in the specification of the mechanosensory neuron cell types in Caenorhabditis elegans

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Abstract
The mec‐3 gene, a member of the LIM‐homeodomain transcription factors, is required for touch receptor, FLP and PVD neurons to differentiate in the nematode Caenorhabditis elegans. Stably integrated transgenic strains with mec‐3‐lacZ fusion were generated by irradiating UV light to an unstable transgenic strain with the extrachromosomal DNA. Expression patterns of the mec‐3‐lacZ fusion were examined in mutant backgrounds (lin‐4, lin‐14, egl‐44, egl‐46 and sem‐4 genes) which alter touch receptor‐specific gene expression. In the lin‐4 mutant background, ectopic mec‐3‐lacZ positive AVM/PVM‐like cells were observed in 9% of the animals. By contrast, in the lin‐14 mutant background, mec‐3‐lacZ staining in AVM/PVM cells was lost in 86% of the animals. In the egl‐44 and egl‐46 mutant backgrounds, expression pattern was the same as wild‐type animals. In the sem‐4 mutant background, more than half of the animals (54–69%) had ectopic staining cells in the tail in addition to the wild‐type staining pattern. The modes of action of these genetically interacting genes in the differentiation of mechanosensory neurons are proposed.