In wild-type C. elegans, touch cell fate is restricted to a set of six cells. In
egl-44 mutants, an extra pair of neurons, the FLP cells, express touch receptor-like features.
egl-44 was first identified as a gene needed for the development of the HSN neurons (Desai et al., 1988; Desai and Horvitz, 1989). Thus,
egl-44 appears to affect several different neurons. We cloned
egl-44 by transformation rescue with cosmid F28B12 and identified the mutations in the three known
egl-44 alleles. The exon-intron structure has been derived through sequencing a cDNA and
egl-44 transcript(2.1kb) has been identified by northern blotting.
egl-44 encodes a protein of 471 amino acids with similarity to members of the TEF(transcriptional enhancer factor) family. These proteins are conserved from yeast to human and are involved in a variety of developmental processes. Like other family members, the predicted EGL-44 protein contains a specific DNA-binding domain(the TEA/ATTS domain) in the N-terminal region and a transcriptional regulation domian in the C-terminal region.
egl-44::lacZ and
egl-44::GFP reporter constructs are expressed throughout the pharynx, a few neurons in the head and some intestinal cells. The identities of the staining cells are being determined. Some staining in the region near FLP suggests that these cells may express
egl-44. We hope to study the interaction of
egl-44 with related genes, particularly
egl-46, which can be mutated to a similar phenotype, to understand how cell fates are regulated during neural development. References: Desai, C. and Horvitz, R. 1989. Caenorhabditis elegans mutants defective in the functioning of the motor neurons responsible for egg laying. Genetics 121: 703-721 Desai, C., Garriga, G., McIntire, S.L. and Horvitz, R. 1988. A genetic pathway for the development of the Caenorhabditis elegans HSN motor neurons. Nature 336: 638-646