Hu Yong-Hua, Zhang Jian
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Fish Shellfish Immunol. 2015 Aug;45(2):771-9. doi: 10.1016/j.fsi.2015.05.043. Epub 2015 Jun 5.
CC chemokines are the largest subfamily of chemokines, which are important components of the innate immune system. To date, sequences of several CC chemokines have been identified in half-smooth tongue sole (Cynoglossus semilaevis); however, the activities and functions of these putative chemokines remain unknown. Herein, we characterized a CC chemokine, CsCCL17, from tongue sole, and examined its activity. CsCCL17 contains a 303 bp open reading frame, which encodes a polypeptide of 100 amino acids with a molecular mass of 12 kDa CsCCL17 is phylogenetically related to the CCL17/22 group of CC chemokines and possesses the typical arrangement of four cysteines and an SCCR motif found in known CC chemokines. Under normal physiological conditions, CsCCL17 expression was detected in spleen, liver, heart, gill, head kidney, muscle, brain, and intestine. When the fish were infected by bacterial and viral pathogens, CsCCL17 expression was significantly up-regulated in a time-dependent manner. Chemotactic analysis showed that recombinant CsCCL17 (rCsCCL17) induced migration of peripheral blood leukocytes. A mutagenesis study showed that when the two cysteine residues in the SCCR motif were replaced by serine, no apparent chemotactic activity was observed in the mutant protein rCsCCL17M. rCsCCL17 enhanced the resistance of tongue sole against viral infection, but rCsCCL17M lacked this antiviral effect. Taken together, these findings indicate that CsCCL17 is a functional CC chemokine with the ability to recruit leukocytes and enhance host immune defense in a manner that requires the conserved SCCR motif.
CC趋化因子是趋化因子中最大的亚家族，是天然免疫系统的重要组成部分。迄今为止，已在半滑舌鳎（Cynoglossus semilaevis）中鉴定出几种CC趋化因子的序列；然而，这些假定趋化因子的活性和功能仍不清楚。在此，我们对舌鳎的一种CC趋化因子CsCCL17进行了表征，并检测了其活性。CsCCL17包含一个303 bp的开放阅读框，编码一个100个氨基酸的多肽，分子量为12 kDa。CsCCL17在系统发育上与CC趋化因子的CCL17/22组相关，并且具有已知CC趋化因子中发现的四个半胱氨酸和一个SCCR基序的典型排列。在正常生理条件下，在脾脏、肝脏、心脏、鳃、头肾、肌肉、脑和肠道中检测到CsCCL17的表达。当鱼受到细菌和病毒病原体感染时，CsCCL17的表达以时间依赖性方式显著上调。趋化分析表明，重组CsCCL17（rCsCCL17）诱导外周血白细胞迁移。诱变研究表明，当SCCR基序中的两个半胱氨酸残基被丝氨酸取代时，突变蛋白rCsCCL17M未观察到明显的趋化活性。rCsCCL17增强了舌鳎对病毒感染的抵抗力，但rCsCCL17M缺乏这种抗病毒作用。综上所述，这些发现表明CsCCL17是一种功能性CC趋化因子，具有招募白细胞并以需要保守SCCR基序的方式增强宿主免疫防御的能力。
