Molecular clone and characterization of c-Jun N-terminal kinases 2 from orange-spotted grouper, Epinephelus coioides

c-Jun N-terminal kinase 2 (JNK2) is a multifunctional mitogen-activated protein kinases involving in cell differentiation and proliferation, apoptosis, immune response and inflammatory conditions. In this study, we reported a new JNK2 (Ec-JNK2) derived from orange-spotted grouper, Epinephelus coioides. The full-length cDNA of Ec-JNK2 was 1920 bp in size, containing a 174 bp 5'-untranslated region (UTR), 483 bp 3'-UTR, and a 1263 bp open reading frame (ORF), which encoded a putative protein of 420 amino acids. The deduced protein sequence of Ec-JNK2 contained a conserved Thr-Pro-Tyr (TPY) motif in the domain of serine/threonine protein kinase (S-TKc). Ec-JNK2 has been found to involve in the immune response to pathogen challenges in vivo, and the infection of Singapore grouper iridovirus (SGIV) in vitro. Immunofluorescence staining showed that Ec-JNK2 was localized in the cytoplasm of grouper spleen (GS) cells, and moved to the nucleus after infecting with SGIV. Ec-JNK2 distributed in all immune-related tissues examined. After challenging with lipopolysaccharide (LPS), SGIV and polyriboinosinic polyribocytidylic acid (poly I:C), the mRNA expression of Ec-JNK2 was significantly (P < 0.01) up-regulated in juvenile orange-spotted grouper. Over-expressing Ec-JNK2 in fathead minnow (FHM) cells increased the SGIV infection and replication, while over-expressing the dominant-negative Ec-JNK2Δ181-183 mutant decreased it. These results indicated that Ec-JNK2 could be an important molecule in the successful infection and evasion of SGIV.