Molecular cloning and characterization of orange-spotted grouper (Epinephelus coioides) CXC chemokine ligand 12.

Chemokines are a family of soluble peptides that can recruit a wide range of immune cells to sites of infection and disease. The CXCL12 is a chemokine that binds to its cognate receptor CXCR4 and thus involved in multiple physiological and pathophysiological processes. In this study, we cloned and characterized CXCL12 from Epinephelus coioides (osgCXCL12). We found that the open reading frame of osgCXCL12 consists of 98 amino acid residues with the small cytokine C-X-C domain located between residues 29 and 87. Higher expression levels for osgCXCL12 were detected at the kitting stage, compared with the prolarva and larva shape stages. The expression patterns revealed that osgCXCL12 may play a key role in early grouper development. We detected mRNA transcripts for osgCXCL12 in healthy tissues and found the highest osgCXCL12 expression in the head kidney. Furthermore, a time-course analysis revealed significantly increased osgCXCL12 and osgCXCR4 expression levels after the nervous necrosis virus (NNV) challenge. In addition, expression of osgCXCL12 was affected by injection with microbial mimics [LPS and poly(I:C)]. These results suggest that osgCXCL12 is associated with inflammatory and developmental processes in the grouper.