Biosynthesis of human endothelins in transformants expressing cDNAs for human prepro-endothelins

Cloning of bovine preproendothelin-2 cDNA and organ distribution of transcripts

Endothelin-2 (ET2), which was originally identified in human, is a bioactive peptide of 21 amino acids with strong vasoconstrictive and pressor effects. Here we report the cDNA cloning and characterization of bovine preproendothelin-2 (PPET2), the precursor form of ET2. The bovine cDNA encodes 177 amino acids of the PPET2 polypeptide, in which a 21-amino acid mature ET2 peptide and a 16-amino acid ET2-like peptide as well as a 23-amino acid putative signal peptide were found. The bovine ET2-like peptide sequence was missing a dibasic amino acid pair at the C-terminal, in contrast to human, mouse and rat, for which the ET2-like sequence is flanked by dibasic pairs at both the N- and C-terminals. Gene expression analysis by RT-PCR showed that the transcript is expressed in various organs including heart, lung, liver, kidney, gastrointestinal tract, uterus and ovary, but not in spleen. Within the gastrointestinal tract, gene expression was detected in rumen, a ruminant-specific digestive organ, as well as stomach, duodenum and colon.

Interaction of endothelin-3 with endothelin-B receptor is essential for development of epidermal melanocytes and enteric neurons

Defects in the gene encoding the endothelin-B receptor produce aganglionic megacolon and pigmentary disorders in mice and humans. We report that a targeted disruption of the mouse endothelin-3 ligand (EDN3) gene produces a similar recessive phenotype of megacolon and coat color spotting. A natural recessive mutation that results in the same developmental defects in mice, lethal spotting (ls), failed to complement the targeted EDN3 allele. The ls mice carry a point mutation of the EDN3 gene, which replaces the Arg residue at the C-terminus of the inactive intermediate big EDN3 with a Trp residue. This mutation prevents the proteolytic activation of big EDN3 by ECE-1. These findings indicate that interaction of EDN3 with the endothelin-B receptor is essential in the development of neural crest-derived cell lineages. We postulate that defects in the human EDN3 gene may cause Hirschsprung's disease.