College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China.
Dev Comp Immunol. 2013 Mar;39(3):133-46. doi: 10.1016/j.dci.2012.11.008. Epub 2012 Dec 7.
High mobility group box 1 (HMGB1) is a nuclear weapon in the immune arsenal and a master regulator of innate immunity, at the crossroads between innate and adaptive immunity. To clarify the immune characterizations of HMGB1 in fishes, two co-orthologs of HMGB1 (CiHMGB1a and CiHMGB1b) were identified in grass carp Ctenopharyngodon idella by local EST database searching and RACE techniques. mRNA expressions of the two HMGB1 genes are widespread in fifteen tissues investigated. The transcripts of CiHMGB1a and CiHMGB1b were significantly up-regulated and reached peak at 24h post GCRV challenge in spleen and head kidney tissues (P<0.05). The modulations are slow post-bacterial PAMP stimulations by contrast with those after viral PAMP or GCRV challenge. They are inhibited by bacterial PAMPs, but are enhanced by viral PAMP or virus. mRNA expression of CiHMGB1a is high and strongly modulated by nucleic acids and transcription of CiHMGB1b is low and mildly regulated by nucleic acids and capsids of GCRV. The over-expression vectors were constructed and transfected into C. idella kidney cell line to obtain stably expressing recombinant proteins. In HMGB1 over-expressed cells, mRNA expressions of IPS-1, MyD88 and Mx1 were down-regulated, whereas TRIF was found to be up-regulated and IFN-I showed no change in its expression. After GCRV challenge, the transcripts of IPS-1, MyD88 and Mx1 were up-regulated, while IFN-I showed down-regulation, and TRIF showed up-regulation after an initial phase of decline. The titer assay demonstrated no antiviral activity of HMGB1s. The results indicated mRNA expressions of HMGB1a and HMGB1b are enhanced by GCRV or viral PAMP, and are inhibited by bacterial PAMPs; HMGB1a and HMGB1b collaborate with each other and play important roles in modulating the innate immune responses, although without direct antiviral effect; the immune network triggered by HMGB1 work together in concert to maintain homeostasis.
高迁移率族蛋白 B1（HMGB1）是免疫武器库中的核武器，也是天然免疫的主要调节剂，位于天然免疫和适应性免疫的交叉点。为了阐明鱼类中 HMGB1 的免疫特征，通过本地 EST 数据库搜索和 RACE 技术，在草鱼（Ctenopharyngodon idella）中鉴定了两个 HMGB1 的共直系同源物（CiHMGB1a 和 CiHMGB1b）。在所研究的 15 种组织中，这两个 HMGB1 基因的 mRNA 表达广泛存在。CiHMGB1a 和 CiHMGB1b 的转录物在 GCRV 攻毒后 24 小时在脾脏和头肾组织中显著上调并达到峰值（P<0.05）。与病毒 PAMP 或 GCRV 攻毒后相比，细菌 PAMP 刺激后的调节速度较慢。它们被细菌 PAMPs 抑制，但被病毒 PAMP 或病毒增强。CiHMGB1a 的 mRNA 表达水平较高，受核酸强烈调节，CiHMGB1b 的转录水平较低，受 GCRV 的核酸和衣壳的轻度调节。构建了过表达载体并转染到草鱼肾脏细胞系中，获得稳定表达重组蛋白的细胞。在 HMGB1 过表达细胞中，IPS-1、MyD88 和 Mx1 的 mRNA 表达下调，而 TRIF 上调，IFN-I 的表达不变。在 GCRV 攻毒后，IPS-1、MyD88 和 Mx1 的转录物上调，而 IFN-I 下调，TRIF 在初始下调阶段后上调。滴度测定表明 HMGB1s 没有抗病毒活性。结果表明，GCRV 或病毒 PAMP 增强了 HMGB1a 和 HMGB1b 的 mRNA 表达，而细菌 PAMPs 抑制了它们的表达；HMGB1a 和 HMGB1b 相互协作，在调节先天免疫反应中发挥重要作用，尽管没有直接的抗病毒作用；HMGB1 触发的免疫网络协同作用以维持体内平衡。
