Cloning of endothelin-1 (ET-1) from European sea bass (Dicentrarchus labrax) and its gene expression analysis in larvae with retinoic acid-induced malformations

It is known in vertebrates that endothelin-1 (ET-1) plays a key role in morphogenesis whose expression level greatly influences the development of craniofacial malformations. In the present study, the complete cDNA fragment encoding a precursor of endothelin-1, the preproendothelin-1 (PPET1), was cloned by RACE-PCR from European sea bass. The cDNA encoded a 199 amino acid polypeptide that was composed of the “mature” and “big” ET-1. Relative ET-1 expression levels were investigated in European sea bass larvae fed microparticulate diets containing the standard amount (0.08 g retinol/kg diet: group N) or an excess of retinoic acid which induces skeletal malformations (0.5 g retinol/kg diet: group RA). Real-time reverse transcription polymerase chain reaction analysis revealed that \{PPET1\} mRNA levels were sensitively reduced in the \{RA\} group during early development (days 10 and 15 post hatching). Regulation of ET-1 gene expression in larvae fed the teratogenic level of vitamin A confirmed the involvement of ET-1 in the molecular mechanism involved in craniofacial deformities. These results suggest that the expression level of ET-1 may be used as a precocious molecular marker to predict malformations during European sea bass development.