Phylogenetic And Expression Analysis Of Nine CC Chemokines And Six Suppressors Of Cytokine Signaling Of Cynoglossus Semilaevis

In this study, we have identified and characterized nine CC chemokines (CCL) and six suppressors of cytokine signaling (SOCS) from half smooth tongue sole (Cynoglossus semilaevis). We also performed their tissue specific expression patterns under normal physiological conditions and their expression profiles in response to the challenge of Vibrio harveyi, Edwardsiella tarda and megalocytivirus RBIV-C1.CC chemokines are a large, diverse group of small cytokines plays a pivotal role in host defense by inducing leukocyte chemotaxis under physiological and inflammatory conditions. Tongue sole is a species of great economic importance in aquaculture. In this study, we named these chemokines according to the results of the phylogenetic tree, which showed that the nine CCLs distributed in different phylogenetic groups. The tissue specific expression patterns of the 9 chemokines under normal physiological conditions varied much, with most chemokines highly expressed in immune organs, such as head kidney, gill and intestine.In addition, the 9 chemokines exhibited similar or distinctly different expression profiles in a tissue-specific and time-dependent manner. The expression level of CsCCL20a and CsCCL21 were extremely high, which may serve as gene markers linked to antibacterial immunity in tongue sole. These results suggest they are inflammatory chemokines that react quickly to pathogen invasion. Meanwhile, CsCCL20b and CsCCL27a showed weak reactions to bacterial and viral pathogen, suggesting that they are likely homeostatic chemokines. These results indicate that in tongue sole, CC chemokines may be involved in different immune responses as homeostatic or inflammatory chemokines.Suppressors of cytokine signaling (SOCS) family is a group of important feedback inhibitors of cytokine receptor signaling in case that excessive cytokine signaling disrupt the normal homeostasis and cellular functions. They have been extensively studied in mammalian models, but systematic analyses of SOCS in teleost species are limited. In the current study, all six SOCS genes (CsSOCS2 to CsSOCS7) from tongue sole (Cynoglossus semilaevis) exhibit conserved structures of SOCS and were phylogenetically grouped together with the respective SCOS members known in mammalian and teleost species. Under normal physiological conditions, the expression of the six CsSOCS genes were detected at varied levels in nine major tissues, with most CsSOCS highly expressed in head kidney, gill and spleen. Most CsSOCS genes exhibited distinctly different expression profiles in a time-, tissue-, and pathogen-dependent manner. These results indicate that the same bacterial pathogen induces different expression patterns for the six CsSOCS genes, suggesting that different members of SOCS may play different roles in tongue sole. In general, E. tarda enhanced the expressions of CsSOCS in more tissues and with higher induction folds than V. harveyi. It is possible that the augmented expressions of these SCOS members in fish tissues may facilitate bacterial invasion by inhibiting the expression of cytokines with antibacterial functions.