尼罗罗非鱼traf6基因表达谱及信号转导

EXPRESSION PROFILES AND SIGNAL TRANSDUCTION OF TRAF6 IN NILE TILAPIA

肿瘤坏死因子受体相关因子6(TRAF6)是一种重要的接头蛋白,在Toll样受体/白细胞介素-1受体(TLR/IL-1R)超家族所触发的信号通路中起重要作用,与先天性免疫密切相关。文章研究了尼罗罗非鱼(Oreochromis niloticus)traf6的表达模式和初步的功能。在健康鱼中,traf6转录本广泛表达于所有受检组织中,在血液中表达水平最高,在肝脏中最低。在不同的胚胎发育阶段也检测到traf6的表达。在无乳链球菌体内感染后,大多数受检组织中traf6 mRNA的表达量上调。此外,LPS、Poly I:C和S.agalactiae可显著诱导尼罗罗非鱼巨噬细胞traf6的表达。此外,在HEK293T细胞中过表达表明,TRAF6分布于细胞质中,可显著提高NF-κB的活性。免疫共沉淀(Co-IP)实验表明,TRAF6可与IRAK1(白细胞介素-1受体相关激酶1)相互作用,IRAK1在TLR/IL-1R信号通路中也起重要作用。在体内,TLR2、TLR21和TLR13b的过表达可上调traf6 mRNA的表达水平,表明TRAF6参与了TLR2、TLR21和TLR13b介导的信号转导,提示TRAF6在病原体入侵的免疫应答中起重要作用。

Tumour necrosis factor receptor-associated factor 6(TRAF6)is a key adaptor protein that plays important role in signalling pathways triggered by the Toll-like receptor/interleukin-1 receptor(TLR/IL-1R)superfamily,which is highly involved in innate immunity.In this study,we investigated expression patterns and preliminary functional analyses of Nile tilapia traf6.In healthy fish,traf6 transcripts were broadly expressed in all examined tissues with the highest expression level in the blood and the lowest in the liver.traf6 was also detected at various embryonic developmental stages.After challenge with S.agalactiae in vivo,upregulated mRNA expression of traf6 was observed in most examined tissues.Moreover,traf6 expression could be significantly induced in Nile tilapia macrophages by treatment with LPS,Poly I:C and S.agalactiae.In addition,overexpression in HEK293T cells showed that TRAF6 was distributed in the cytoplasm and could significantly increase NF-κB activation.Co-immunoprecipitation(Co-IP)assays showed that TRAF6 could interact with IRAK1(interleukin-1 receptor associated kinase 1),which also plays a vital role in the TLR/IL-1R signalling pathway.In vivo,TLR2,TLR21 and TLR13b overexpression could upregulate traf6 expression levels,which indicates that TRAF6 is involved in the signal transduction of TLR2,TLR21 and TLR13b.These findings suggest that TRAF6 plays important roles in the immune response to pathogen invasion.