内源性H2S促进SIRT3线粒体转位调控糖尿病心肌糖脂代谢的研究

Hyperglycemia and hyperlipidemia are the main reasons to induce diabetic cardiomyopatthy(DCM). At present, the studies focus on the apoptosis and autophage in DCM. However, it is neglected to research glucose and fatty acid metabolism in DCM. H2S has extensive biological functions, including acelyation and polysulfide for proteins. Our previous LC-MS results demonstrated that acelyation to the key enzymes for glucose and fatty acid metabolism has been increased in db/db mice, whereas, exogenous H2S reversed acelyation of these enzymes, ameolirating the cardiac functions. We hypothesize “ Endogenous H2S regulates the activity of Nampt and NAD+/NADH level to increase the expression and activity SIRT3 and SIRT1 and promoting SIRT3 translocation to mitochondria and SIRT1 tanslocation to nuclei to modulating glucose and fatty acid metabolism and effect on mitochondrial functions and initiates the protection against DCM.” Db/db mice and rat neonatal cardiomyocytes as experimental model, this grant is tested that H2S is involved in regulating the expression of SIRT3 and how its gene is modulated. We also confirmed that H2S affect glucose and fatty acid metabolism to protect diabetic cardiomyopathy.The goal of this study is to investigate the protective role and its mechanisms of H2S and to provide a new idea to therapy in diabetic cardiomyopathy.

高糖高脂是诱导糖尿病心肌病的主要原因,目前研究集中在其诱导心肌细胞凋亡及自噬，葡萄糖和脂肪酸代谢异常引发糖尿病心肌病的机制尚不清楚。研究证实H2S具有广泛的生物学功能，可调控蛋白乙酰化和多硫化，从而影响细胞功能。我们前期结果证实，db/db小鼠心肌组织中H2S含量降低，LC-MS结果证实糖脂代谢关键酶乙酰化水平改变，给予外源性H2S后，其关键酶乙酰化水平及活性逆转，心脏功能明显改善。我们推测“内源性H2S通过调控Nampt活性，增加SIRT3活性并促进其线粒体转位，调控心肌线粒体脂肪酸氧化向葡萄糖氧化转变，从而改善线粒体多重功能，启动糖尿病心肌的保护作用”。本项目以db/db小鼠心肌和乳鼠心肌细胞为研究对象，揭示H2S如何调控SIRT3的基因表达并参与调控线粒体糖脂代谢的转化，阐明对糖尿病心肌细胞保护作用的机制。本课题在器官、细胞、线粒体及分子水平上阐明H2S防治糖尿病心肌病的新机制。

高糖高脂是诱导糖尿病心肌病的主要原因,目前研究集中在其诱导心肌细胞凋亡及自噬，葡萄糖和脂肪酸代谢异常引发糖尿病心肌病的机制尚不清楚。研究证实H2S具有广泛的生物学功能，可调控蛋白乙酰化和多硫化，从而影响细胞功能。我们前期结果证实，db/db小鼠心肌组织中H2S含量降低，LC-MS结果证实糖脂代谢关键酶乙酰化水平改变，给予外源性H2S后，其关键酶乙酰化水平及活性逆转，心脏功能明显改善。我们推测“内源性H2S通过调控Nampt活性，增加SIRT3活性并促进其线粒体转位，调控心肌线粒体脂肪酸氧化向葡萄糖氧化转变，从而改善线粒体多重功能，启动糖尿病心肌的保护作用”。我们的研究采用db/db小鼠心肌和乳鼠心肌细胞为研究对象，我们的结果证实，外源性H2S增加了db/db小鼠心肌组织中H2S的含量，减轻了CSE蛋白的降解；外源性H2S可以提高db/db小鼠中NAD+/NADH的比值而促进SIRT3的表达，从而降低db/db小鼠线粒体糖脂代谢关键酶乙酰化水平而改善能量底物代谢酶活性，增加葡萄糖有氧氧化、降低脂肪酸代谢，从而调控心肌能量底物代谢从对脂肪酸β-氧化的利用转换成葡萄糖氧化；外源性H2S可以提高SIRT3的活性和表达降低线粒体呼吸链相关酶乙酰化水平，改善线粒体功能。外源性H2S可以降低高糖高脂诱导的心肌细胞线粒体分裂；通过多硫化修饰促进USP8的表达，从而促进Parkin去泛素化，增强心肌细胞的线粒体自噬发生。外源性H2S可以改善db/db小鼠心肌细胞中内质网应激，改善db/db小鼠心脏舒缩功能；H2S通过对MuRF1的泛素化作用降低与心肌结构蛋白MYH6和MyL2的相互作用，减轻了糖尿病心脏心肌结构的降解。本课题在器官、细胞、线粒体及分子水平上阐明H2S防治糖尿病心肌病的新机制。