State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, PR China.
State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China.
Fish Shellfish Immunol. 2020 Jul;102:350-360. doi: 10.1016/j.fsi.2020.04.060. Epub 2020 May 1.
Succinate dehydrogenase (SDH) is a mitochondrial enzyme with the unique ability to participate in both the tricarboxylic acid cycle and the electron transport chain to produce reactive oxygen species (ROS). The B subunit of SDH is required for succinate oxidation, which is critical for pro-inflammatory response. In this study, we cloned the iron-sulfur protein subunit of SDH from Apostichopus japonicus (denoted as AjSDHB) via RACE technology and explored its role in the immune system as a response to pathogen infection. The full-length cDNA of AjSDHB was 1442 bp with a complete open reading frame of 858 bp encoding 286 amino acids. Simple modular architecture research tool analysis revealed that AjSDHB contained two conserved domains, including a 2Fe-2S iron-sulfur cluster binding domain and a 4Fe-4S dicluster domain, without a signal peptide. Multiple sequence alignment demonstrated that AjSDHB shared a high degree of structural conservation and sequence identities with other counterparts from invertebrates and vertebrates. Phylogenetic analysis supported the finding that AjSDHB is a new member of the SDHB protein subfamily. Tissue distribution analysis revealed that AjSDHB was expressed in all examined tissues and particularly highly expressed in the muscles. AjSDHB transcripts were markedly induced in coelomocytes both by Vibrio splendidus challenge in vivo and lipopolysaccharide exposure in vitro. Function analysis showed that siRNA-mediated AjSDHB knockdown could substantially reduce the mitochondrial membrane potential (ΔΨm) and further decrease mitochondrial ROS production in A. japonicus coelomocytes. By contrast, AjSDHB overexpression considerably increased ΔΨm and mitochondrial ROS production of A. japonicus coelomocytes. These results supported the idea that AjSDHB is involved in the innate immunity of A. japonicus through its participation in mitochondrial ROS generation.
琥珀酸脱氢酶（SDH）是一种具有独特能力的线粒体酶，既能参与三羧酸循环，又能参与电子传递链产生活性氧（ROS）。SDH 的 B 亚基是琥珀酸氧化所必需的，这对促炎反应至关重要。在这项研究中，我们通过 RACE 技术从刺参（Apostichopus japonicus）中克隆了 SDH 的铁硫蛋白亚基（命名为 AjSDHB），并探讨了其作为对病原体感染的免疫反应中的作用。AjSDHB 的全长 cDNA 为 1442bp，完整的开放阅读框为 858bp，编码 286 个氨基酸。简单模块化架构研究工具分析表明，AjSDHB 包含两个保守结构域，包括一个 2Fe-2S 铁硫簇结合域和一个 4Fe-4S 双簇域，没有信号肽。多重序列比对表明，AjSDHB 与其他无脊椎动物和脊椎动物的同源物在结构上高度保守且具有序列同一性。系统发育分析支持 AjSDHB 是 SDHB 蛋白亚家族的一个新成员的发现。组织分布分析表明，AjSDHB 在所有检测组织中均有表达，在肌肉中表达尤为丰富。AjSDHB 转录物在体内 Vibrio splendidus 攻击和体外脂多糖暴露后，在体腔细胞中均明显诱导。功能分析表明，siRNA 介导的 AjSDHB 敲低可显著降低刺参体腔细胞的线粒体膜电位（ΔΨm），并进一步降低线粒体 ROS 的产生。相比之下，AjSDHB 的过表达可显著增加刺参体腔细胞的ΔΨm 和线粒体 ROS 的产生。这些结果支持了 AjSDHB 通过参与线粒体 ROS 生成参与刺参先天免疫的观点。
