Molecular cloning and expression analysis of interferon-gamma-inducible-lysosomal thiol reductase gene in orange-spotted grouper, Epinephelus coioides.

In mammals, interferon-gamma-inducible-lysosomal thiol reductase (GILT) has been demonstrated to play a key role in the processing and presentation of MHC class II-restricted antigen (Ag) by catalyzing disulfide bond reduction, thus unfolding native protein Ag and facilitating subsequent cleavage by proteases. In this study a cDNA containing the orange-spotted grouper GILT (OsgGILT) coding sequence has been cloned and its complete sequence determined. The full-length cDNA of OsgGILT gene is 1066 bp nucleotides (nt) encoding a protein of 260 amino acids (aa), with a putative molecular weight of 28.7 kDa. The deduced OsgGILT possesses the typical structural feature of mammalian GILT, including an active-site CXXC motif, a GILT signature sequence CQHGX(2)ECX(2)NX(4)C, and 10 conserved cysteines. The result of real-time PCR showed that OsgGILT mRNA was expressed in heart, liver, brain, gill, kidney and muscle and more highly expressed in spleen. The OsgGILT expression is obviously up-regulated in spleen and kidney after induction with LPS, these results suggest that OsgGILT may be involved in the immune response to LPS challenge in orange-spotted grouper.