Sun Yu, Lu Fanghao, Yu Xiangjing, Wang Bingzhu, Chen Jian, Lu Fangping, Peng Shuo, Sun Xiaojiao, Yu Miao, Chen He, Wang Yan, Zhang Linxue, Liu Ning, Du Haining, Zhao Dechao, Zhang Weihua
1Department of Pathophysiology, Harbin Medical University, Harbin, China.
2Department of Forensic Medicine, Harbin Medical University, Harbin, China.
Aging Dis. 2020 Mar 9;11(2):269-285. doi: 10.14336/AD.2019.0524. eCollection 2020 Apr.
Hydrogen sulfide (HS), an important gasotransmitter, regulates cardiovascular functions. Mitochondrial damage induced by the overproduction of reactive oxygen species (ROS) results in myocardial injury with a diabetic state. The purpose of this study was to investigate the effects of exogenous HS on mitophagy formation in diabetic cardiomyopathy. In this study, we found that exogenous HS could improve cardiac functions, reduce mitochondrial fragments and ROS levels, enhance mitochondrial respiration chain activities and inhibit mitochondrial apoptosis in the hearts of db/db mice. Our results showed that exogenous HS facilitated parkin translocation into mitochondria and promoted mitophagy formation in the hearts of db/db mice. Our studies further revealed that the ubiquitination level of cytosolic parkin was increased and the expression of USP8, a deubiquitinating enzyme, was decreased in db/db cardiac tissues. S-sulfhydration is a novel posttranslational modification of specific cysteine residues on target proteins by HS. Our results showed that the S-sulfhydration level of USP8 was obviously decreased in vivo and in vitro under hyperglycemia and hyperlipidemia, however, exogenous HS could reverse this effect and promote USP8/parkin interaction. Dithiothreitol, a reducing agent that reverses sulfhydration-mediated covalent modification, increased the ubiquitylation level of parkin, abolished the effects of exogenous HS on USP8 deubiquitylation and suppressed the interaction of USP8 with parkin in neonatal rat cardiomyocytes treated with high glucose, oleate and palmitate. Our findings suggested that HS promoted mitophagy formation by increasing S-sulfhydration of USP8, which enhanced deubiquitination of parkin through the recruitment of parkin in mitochondria.
硫化氢（HS）作为一种重要的气体信号分子，可调节心血管功能。活性氧（ROS）过量产生所导致的线粒体损伤会引发糖尿病状态下的心肌损伤。本研究旨在探讨外源性HS对糖尿病心肌病中线粒体自噬形成的影响。在本研究中，我们发现外源性HS可改善db/db小鼠心脏的心脏功能，减少线粒体片段和ROS水平，增强线粒体呼吸链活性并抑制线粒体凋亡。我们的结果表明，外源性HS促进了帕金森蛋白向线粒体的转位，并促进了db/db小鼠心脏中的线粒体自噬形成。我们的研究进一步揭示，db/db心脏组织中胞质帕金森蛋白的泛素化水平升高，而去泛素化酶USP8的表达降低。S-硫巯基化是HS对靶蛋白上特定半胱氨酸残基进行的一种新型翻译后修饰。我们的结果表明，在体内和体外的高血糖和高血脂条件下，USP8的S-硫巯基化水平明显降低，然而，外源性HS可逆转这种效应并促进USP8/帕金森蛋白的相互作用。二硫苏糖醇是一种可逆转硫巯基化介导的共价修饰的还原剂，它增加了帕金森蛋白的泛素化水平，消除了外源性HS对USP8去泛素化的影响，并抑制了高糖、油酸和棕榈酸处理的新生大鼠心肌细胞中USP8与帕金森蛋白的相互作用。我们的研究结果表明，HS通过增加USP8的S-硫巯基化促进线粒体自噬形成，这通过将帕金森蛋白募集到线粒体中增强了帕金森蛋白的去泛素化作用。
