Recombinant Expression and Characterization of the β-Integrin Gene of Solen grandis

Abstract:

Integrins are heterodimeric cell surface receptors that consist of α and β subunits to regulate cell adhesion, migration, proliferation, apoptosis and phagocytosis. The present study identified the β-integrin gene from Solen grandis (SgβInt) and analyzed the characterization of its encoded protein. The phylogenetic tree was constructed by the neighbor-joining method and the three-dimensional structure was predicted with SWISS-MODEL. The full-length cDNA of SgβInt was 1168 bp, containing a 61 bp 5´UTR, 18 bp 3´UTR and an open reading frame (ORF) of 1089 bp that encodes a polypeptide of 362 amino acids with an estimated molecular mass of 30.0 kDa. The encoded protein of SgβInt shared significant similarities with that in Capra hircus and Mus musculus. The phylogenetic tree indicated that SgβInt had a close genetic relationship with Crassostrea gigas to form a mollusk branch. The three-dimensional structure of SgβInt consisted of one α-helice and nine β-sheets as a member of integrin superfamily. SgβInt expressed in all tested tissues, including mantle, gill, hemocyte, gonad, muscle and hepatopancreas, with the highest expression in gill which was 487.5 times higher than gonad. SgβInt was induced by all the three pathogen associated molecular patterns (PAMPs) including LPS, PGN and glucan with the peak level at 3 and 48 h post LPS and glucan stimulation, respectively. SgβInt expression reached the maximal level at 6 h post PGN stimulation with 53.5-fold induction. All the results revealed that SgβInt might regulate the immune response of S. grandis to microorganism. This study shed new light on the research of β-integrin in mollusk and immune defense mechanism of S. grandis.