Molecular cloning and expression of a smooth muscle-specific gene SM22α in zebrafish

SM22α is a kind of 22-kDa protein which is exclusively expressed in smooth muscle containing tissues of the vertebrates. Here we report molecular cloning of a novel zebrafish SM22α gene. The full length of zebrafish SM22α cDNA is 1296 bp and it encodes a polypeptide of 201 amino acids which shares 69.2%, 69.7%, 69.2%, 67.2%, and 61.2% overall identity with human, mouse, rat, chicken, and bovine SM22α, respectively. Characterization of zebrafish SM22α genomic sequence reveals that it spans 7.7 kb and contains five exons and four introns. The expression pattern of SM22α in zebrafish embryonic development is studied by whole-mount in situ hybridization. Strong expression is observed in vascular, gut, swim bladder, branchial arches, and fin epidermis. Furthermore, we carry out gene knock-down by antisense morpholino oligonucleotide, which results in disappearance of yolk extension, caudal fin aberrance, and deficiency of circulation system in zebrafish embryo. Cross-section of SM22α-deficient embryo suggests that SM22α may play roles in smooth muscle cell morphology transform. [Copyright &y& Elsevier]