Caenorhabditis elegans cog-1 Locus Encodes GTX/Nkx6.1 Homeodomain Proteins and Regulates Multiple Aspects of Reproductive System Development

Abstract

The development of the reproductive system in Caenorhabditis elegans is a well-established model system for patterning and organogenesis. We report the characterization of the cog-1 gene, mutations in which cause novel phenotypes in late patterning in vulval lineages, establishment of the vulva–uterine connection, development and function of the spermathecal–uterine junction, and the development of vas deferens–proctodeal connection in the male. We positionally cloned cog-1 and found that it encodes a homeobox protein most similar to the mammalian GTX and Nkx6.1 proteins. Analysis of cog-1 transcripts revealed that cog-1 is likely a complex locus with two promoters. Two mutant alleles of cog-1 differentially affect alternative transcripts and cause different phenotypes, suggesting that the two forms of cog-1 have distinct functions in C. elegans.