Cloning and expression analysis of a stomatin gene from the sea cucumber Apostichopus japonicas

Abstract

Stomatin was the first member of the stomatin-prohibitin-flotillin-HflC/K (SPFH) superfamily proteins to be studied. It is also known as band 7 integral membrane protein. In this study, a stomatin gene in the sea cucumber Apostichopus japonicus (designated as AjSto) was identified and characterized. Its cDNA was 2085 bp in length including 131 bp of 5’-UTR, 1117 bp of 3’-UTR, and 837 bp of open reading frame (ORF) encoding a putative protein of 279 residues with a SPFH domain of band 7 family, a predicted molecular mass of 30.5 kDa and a theoretical pI of 5.25. Protein structure prediction and phylogenetic analysis showed that AjSto is highly conserved as compared to those from other vertebrate and invertebrate species. Analysis of AjSto expression in the tissues of A. japonicas showed that the respiratory tree and body wall had the highest expression, followed by the intestine, celomocytes, tube feet, and longitudinal muscle. Time-course analysis of AjSto expression in the celomocytes revealed obvious and significant inhibition of expression following Vibrio splendidus challenge, with a 0.18-fold reduction after 6 h of exposure to the bacteria compared to the control, but the expression was up-regulated by 2.12-fold after 72 h of exposure. These results suggested that AjSto might play critical roles not only by acting as the major integral protein of erythrocyte lipid rafts, but may also involved in the innate immune defense against bacterial infections.