ELT-3: ACaenorhabditis elegansGATA Factor Expressed in the Embryonic Epidermis during Morphogenesis

Abstract

We have identified a gene encoding a new member of theCaenorhabditis elegansGATA transcription factor family,elt-3.The predicted ELT-3 polypeptide contains a single GATA-type zinc finger (C-X2-C-X17-C-X2-C) along with a conserved adjacent basic region.elt-3mRNA is present in all stages ofC. elegansdevelopment but is most abundant in embryos. Reporter gene analysis and antibody staining show thatelt-3is first expressed in the dorsal and ventral hypodermal cells, and in hypodermal cells of the head and tail, immediately after the final embryonic cell division that gives rise to these cells. No expression is seen in the lateral hypodermal (seam) cells.elt-3expression is maintained at a constant level in the epidermis until the 212-fold stage of development, after which reporter gene expression declines to a low level and endogenous protein can no longer be detected by specific antibody. A second phase ofelt-3expression in cells immediately anterior and posterior to the gut begins in pretzel-stage embryos.elt-1andlin-26are two genes known to be important in specification and maintenance of hypodermal cell fates. We have found thatelt-1is required for the formation of most, but not all,elt-3-expressing cells. In contrast,lin-26function does not appear necessary forelt-3expression. Finally, we have characterised the candidate homologue ofelt-3in the nematodeCaenorhabditis briggsae.Many features of theelt-3genomic and transcript structure are conserved between the two species, suggesting thatelt-3is likely to perform an evolutionarily significant function during development.