A fork head/HNF-3 homolog expressed in the pharynx and intestine of the Caenorhabditis elegans embryo

We have cloned a member of the fork head/HNF-3 family of transcription factors from the nematode Caenorhabditis elegans. Within the predicted DNA binding domain, this gene, called Ce-Fkh-1, is 75-78% identical to the Drosophila fork head and rat liver HNF-3 alpha, beta, and gamma genes. Ce-Fkh-1 mRNA is highly enriched in embryos. The Ce-Fh-1 gene produces three major transcripts: the longest mRNA retains its original 5'-end but two shorter mRNAs are trans-spliced at the beginning of exons 2 and 3, respectively. In situ hybridization and transgenic Ce-Fkh-1::lacZ reporter constructs indicate that the Ce-Fh-1 gene is expressed in both pharynx and intestine of the embryo, beginning at the midproliferation stage. A second phase of Ce-Fh-1 expression occurs in cells of the larval somatic gonad. The pharynx-gut expression of Ce-Fkh-1 in the C. elegans embryo is compared with expression of fork head throughout the gut of Drosophila embryos and with expression of HNF-3 (alpha beta gamma) in the endoderm of mammalian embryos. Such conserved patterns of gene expression point to universal features of gastrulation and of digestive tract formation. (C) 1996 Academic Press, Inc.