Smoothelin expression during chicken embryogenesis: Detection of an embryonic isoform

Two isoforms of a novel smooth muscle cell (SMC)-specific cytoskeletal prot ein, smoothelin, have been described. In the adult chick, the 55-kDa smooth elin-A is expressed in visceral SMC, whereas the 120-kDa smoothelin-B is th e major product in vascular SMC. Chicken was chosen to study smoothelin exp ression during embryogenesis and neonatally. Smoothelin-B was found in vasc ular SMC from stage 20 onward. In visceral SMC, smoothelin-B was present fr om stage 29 until hatching. Perinatally, a strong up-regulation of smoothel in synthesis was observed in visceral tissues, coinciding with a switch to the A-isoform. Transient smoothelin synthesis was observed in the somites a nd the developing heart. Western blotting revealed in these tissues a 62-kD a smoothelin isoform, designated. smoothelin-C. Expression of the smootheli n isoforms seems to be strictly controlled with respect to cell type and de velopmental stage and may be related to the mode of contraction of the diff erent cells. (C) 2001 Wiley-Liss, Inc.