DataSheet1_FSTL1-USP10-Notch1 Signaling Axis Protects Against Cardiac Dysfunction Through Inhibition of Myocardial Fibrosis in Diabetic Mice.docx

The incidence of type 2 diabetes mellitus (T2DM) has been increasing globally, and T2DM patients are at an increased risk of major cardiac events such as myocardial infarction (MI). Nevertheless, the molecular mechanisms underlying MI injury in T2DM remain elusive. Ubiquitin-specific protease 10 (USP10) functions as a NICD1 (Notch1 receptor) deubiquitinase that fine-tunes the essential myocardial fibrosis regulator Notch signaling. Follistatin-like protein 1 (FSTL1) is a cardiokine with proven benefits in multiple pathological processes including cardiac fibrosis and insulin resistance. This study was designed to examine the roles of FSTL1/USP10/Notch1 signaling in MI-induced cardiac dysfunction in T2DM. High-fat-diet-treated, 8-week-old C57BL/6J mice and db/db T2DM mice were used. Intracardiac delivery of AAV9-FSTL1 was performed in T2DM mice following MI surgery with or without intraperitoneal injection of crenigacestat (LY3039478) and spautin-1. Our results demonstrated that FSTL1 improved cardiac function following MI under T2DM by reducing serum lactate dehydrogenase (LDH) and myocardial apoptosis as well as cardiac fibrosis. Further in vivo studies revealed that the protective role of FSTL1 against MI injury in T2DM was mediated by the activation of USP10/Notch1. FSTL1 protected cardiac fibroblasts (CFs) against DM-MI-induced cardiofibroblasts injury by suppressing the levels of fibrosis markers, and reducing LDH and MDA concentrations in a USP10/Notch1-dependent manner. In conclusion, FSTL1 treatment ameliorated cardiac dysfunction in MI with co-existent T2DM, possibly through inhibition of myocardial fibrosis and apoptosis by upregulating USP10/Notch1 signaling. This finding suggests the clinical relevance and therapeutic potential of FSTL1 in T2DM-associated MI and other cardiovascular diseases.

全球范围内2型糖尿病（type 2 diabetes mellitus, T2DM）的发病率持续攀升，且T2DM患者发生心肌梗死（myocardial infarction, MI）等主要心脏不良事件的风险显著升高。然而，T2DM背景下心肌梗死损伤的分子机制仍未明确。泛素特异性蛋白酶10（ubiquitin-specific protease 10, USP10）可作为Notch1受体胞内域（NICD1，Notch1 receptor）的去泛素化酶，精准调控关键心肌纤维化调控因子Notch信号通路。卵泡抑素样蛋白1（Follistatin-like protein 1, FSTL1）是一种心脏分泌因子，已被证实可在心肌纤维化、胰岛素抵抗等多种病理过程中发挥有益作用。本研究旨在探究FSTL1/USP10/Notch1信号通路在T2DM合并MI诱导的心脏功能障碍中的作用。实验选用高脂饮食喂养的8周龄C57BL/6J小鼠及db/db型T2DM小鼠。在MI造模后的T2DM小鼠中，经心内递送腺相关病毒9-FSTL1（AAV9-FSTL1）载体，并辅以或不辅以腹腔注射克立吉司他（crenigacestat, LY3039478）与spautin-1。研究结果表明，在T2DM背景下，FSTL1可通过降低血清乳酸脱氢酶（lactate dehydrogenase, LDH）水平、减少心肌细胞凋亡及心肌纤维化，改善MI后心脏功能。进一步体内实验显示，FSTL1对T2DM合并MI损伤的保护作用，可通过激活USP10/Notch1信号通路介导。体外实验证实，FSTL1可通过USP10/Notch1依赖的方式，抑制心脏成纤维细胞（cardiac fibroblasts, CFs）的纤维化标志物表达、降低LDH与丙二醛（MDA）浓度，从而减轻糖尿病合并MI诱导的心脏成纤维细胞损伤。综上，FSTL1治疗可改善T2DM合并MI状态下的心脏功能障碍，其潜在机制可能通过上调USP10/Notch1信号通路，抑制心肌纤维化与细胞凋亡。该研究结果提示FSTL1在T2DM相关MI及其他心血管疾病中具有临床应用价值与治疗潜力。