FoxO1巯基硫化修饰在硫化氢抗糖尿病心肌病中的作用及机制研究

Diabetic cardiomyopathy is a common conplication in patients with diabetes mellitus, which can result in cardiac failure and subsequent death. H2S regulates protein post-translational modification termed as S-sulfhydration to exert important effects in various diseases. Yet whether protein S-sulfhydration by H2S mediates diabetic cardiomyopathy remains elusive. FoxO1 is a pleiotropic transcription factor that plays a pivotal role in a variety of physiological processes such as metabolism, oxidative stress and inflammation. Cardiomyocyte-specific deletion of FoxO1 ameliorates DCM in mice, which suggests that FoxO1 is an important mediator of DCM. Our preliminary studies showed that H2S treatment could compensate for the diabetes-induced disturbances on cardiac structure and function. In vitro, H2S decreased ROS levels, inhibited FoxO1 nuclear translocation and augmented FoxO1 S-sulfhydration in hyperglycemia-induced cardiomyocytes. Our project in vivo and in vitro is to validate that H2S may influence FoxO1 nuclear translocation and activity via S-sulfhydration of FoxO1, then modulate oxidative stress and inflammation response in DCM. This may provide a novel target for preventing DCM.

糖尿病心肌病（DCM）是导致糖尿病患者心衰甚至死亡的常见并发症，严重威胁人类健康。硫化氢（H2S）可通过调节蛋白质巯基硫化修饰在多种疾病中发挥作用，但在DCM中的作用及机制尚不明确。FoxO1是调节代谢、炎症、应激等过程的重要转录因子，心肌条件性敲除FoxO1可明显改善DCM，提示FoxO1是DCM的重要分子靶点。我们预实验发现，H2S明显减轻DCM小鼠心肌重构、改善心功能；抑制高糖诱导的心肌细胞活性氧的增加以及FoxO1核转位；增加心肌细胞FoxO1巯基硫化修饰水平。在预实验基础上，本项目拟从离体细胞及整体动物水平验证科学假说，H2S通过上调FoxO1巯基硫化修饰水平，抑制其核转位及活性，影响下游靶基因转录，进而调控氧化应激、炎症相关通路，延缓或逆转糖尿病心肌重构，为阐明DCM机制及寻找防治靶点提供重要依据。

糖尿病早期即可出现心肌结构及功能的异常，随着病情进展，出现心肌肥大、坏死及纤维化，并最终发生心力衰竭。明确糖尿病心肌病的发生机制，寻找早期有效的防控靶点，具有非常重要的意义。硫化氢（H2S）是一种气体信号分子，参与调节炎症介质、对抗氧化应激损伤等病理生理学过程。既往研究显示H2S可通过调控蛋白质翻译后修饰即蛋白质巯基硫化修饰调节蛋白活性、结构及定位。然而，在糖尿病心肌病中，H2S 对蛋白质的巯基硫化修饰是否也发挥关键作用，尚不清楚。通过本研究，我们在离体细胞及整体动物实验上证实了H2S对糖尿病小鼠心脏的保护作用，且发现H2S可显著上调叉头转录因子O1（FoxO1）的巯基硫化修饰水平，并明确H2S通过对FoxO1 半胱氨酸457位点进行修饰，影响高糖刺激下心肌细胞中FoxO1的核转位，进一步抑制FoxO1 下游靶蛋白TXNIP的表达及其与NLRP3的结合，通过调节TXNIP/NLRP3信号通路，抑制 NLRP3炎性复合体形成，从而改善高糖诱发的心肌损伤。本项目揭示了H2S对抗糖尿病心肌病的新机制，为临床干预、治疗糖尿病心肌病提供新的靶点。