Chen Meng, Ding Mingmei, Li Yuan, Zhong Xiaofang, Liu Shuo, Guo Zheng, Yin Xiaoxue, Fu Shengli, Ye Jianmin
Guangdong Provincial Key Laboratory for Health and Safe Aquaculture, Guangdong Provincial Engineering Technology Research Center for Environmentally-Friendly Aquaculture, College of Life Sciences, South China Normal University, Guangdong, 510631, PR China.
Guangdong Provincial Key Laboratory for Health and Safe Aquaculture, Guangdong Provincial Engineering Technology Research Center for Environmentally-Friendly Aquaculture, College of Life Sciences, South China Normal University, Guangdong, 510631, PR China.
Dev Comp Immunol. 2018 Oct;87:98-108. doi: 10.1016/j.dci.2018.05.023. Epub 2018 Jun 8.
Complement component 1q (C1q) is the initial protein of the classical complement pathway and plays an important role in immune response against bacterial infection. In this study, the full-length of C1q subcomponent A, B and C chain genes (C1qA, C1qB and C1qC) were identified and characterized from Nile tilapia (Oreochromis niloticus). Molecular characterization of these three C1q subcomponents (OnC1qs) harbored conserved amino acids through analyses of multiple sequence alignment and phylogenetic tree, which were homologous to other teleost species. Expression analysis revealed that the OnC1qs were highly expressed in liver. After the in vivo challenges of Streptococcus agalactiae and LPS, the mRNA expressions of OnC1qs were significantly up-regulated in liver. Meanwhile, the concentration variation of OnC1qs at the protein level from tilapia serum after challenge with S. agalactiae were measured by a competitive-inhibition ELISA. In addition, the up-regulation expressions of OnC1qs were also demonstrated in head kidney adherent leukocytes and the cell culture medium in vitro stimulation with S. agalactiae, Aeromonas hydrophila and LPS, respectively. Moreover, the recombinant OnC1qs enhanced expression of cytokines IL-6, IL-8 and IL-10 in head kidney adherent leukocytes, and were able to bind both heat-aggregated mouse IgG and IgM. Taken together, the results of this study indicated that OnC1qs might be involved in host defense against bacterial infection in Nile tilapia.
补体成分1q（C1q）是经典补体途径的起始蛋白，在抵抗细菌感染的免疫反应中起重要作用。在本研究中，从尼罗罗非鱼（Oreochromis niloticus）中鉴定并表征了C1q亚成分A、B和C链基因（C1qA、C1qB和C1qC）的全长。通过多序列比对和系统发育树分析，这三个C1q亚成分（OnC1qs）的分子特征具有保守氨基酸，与其他硬骨鱼物种同源。表达分析显示OnC1qs在肝脏中高表达。在用无乳链球菌和脂多糖进行体内攻毒后，肝脏中OnC1qs的mRNA表达显著上调。同时，通过竞争抑制ELISA检测了无乳链球菌攻毒后罗非鱼血清中OnC1qs在蛋白质水平的浓度变化。此外，在用无乳链球菌、嗜水气单胞菌和脂多糖分别进行体外刺激时，OnC1qs在头肾贴壁白细胞和细胞培养基中的上调表达也得到了证实。此外，重组OnC1qs增强了头肾贴壁白细胞中细胞因子IL-6、IL-8和IL-10的表达，并且能够结合热聚集的小鼠IgG和IgM。综上所述，本研究结果表明OnC1qs可能参与尼罗罗非鱼对细菌感染的宿主防御。
