Two novel p38 MAPKs identified from Epinephelus coioides and their expression pattern in response to Cryptocaryon irritans infection

mitogen-activated protein kinases (MAPKs) are one of the most important central regulatory proteins response to extra environmental stresses. In this study, two novel p38 MAPKs, Ec-P38 gamma and Ec-P38 delta, were identified from Epinephelus coioides, an economically important cultured fish in China and Southeast Asian counties. Both of Ec-p38 gamma and Ec-p38 delta sequences contain a serine/threonine protein kinase (S_TKc) domain and a highly conserved Thr-Gly-Tyr (TGY) motif. Analysis of phylogenetic relationships illustrated that p38 amino acid sequences were conserved between different species indicating that the functions may be similar. The four subtypes of p38 (alpha, beta, gamma, and delta) mRNA can be detected in all thirteen tissues examined, but the expression level is different in these tissues. The expression patterns of the four Ec-p38 subtypes in E. coioides were also detected response to Cryptocaryon irritans infection, one of the most important protozoan pathogens of marine fish. The expression of four p38 subtypes was up-regulated in the tissues examined, with the highest expressions of Ec-p38 alpha (5.2 times) and Ec-p38 delta (4.2 times) occurring in the skin, while Ec-p38 beta (24.8 times) and gamma (16.6 times) occurred in the spleen. There was no significantly correlation between the expression of Ec-p38 gamma/Ec-p38 delta and the expression of nuclear factor kappaB (NF-kappa B). The results indicated the sequences and the characters of Ec-p38 gamma and Ec-p38 delta were conserved, the p38 subtypes showed tissue-specific expression patterns in healthy grouper, and their expressions were significantly up-regulated post C. irritans infection, suggesting these p38 MAPKs may play important roles in these tissues during pathogen-caused inflammation. (C) 2017 Elsevier Ltd. All rights reserved.