Cardiovascular diseases are the leading cause of death globally, among which acute myocardial infarction (AMI) frequently occurs in the heart and proceeds from myocardium ischemia and endoplasmic reticulum (ER) stress-induced cell death. Numerous studies on miRNAs indicated their potential as diagnostic biomarkers and treatment targets for heart diseases. Our study investigated the role of miR-17-5p and its regulatory mechanisms during AMI. Echocardiography, MTT, flow cytometry assay, evaluation of caspase-3 and lactate dehydrogenase (LDH) activity were conducted to assess cell viability, apoptosis in an MI/R mice model, and an H₂O₂-induced H9c2 hypoxia cell model, respectively. The expression levels of ER stress response-related biomarkers were detected using qRT-PCR, IHC, and western blotting assays. The binding site of miR-17-5p on Tsg101 mRNA was determined by bioinformatic prediction and luciferase reporter assay. The expression levels of miR-17-5p were notably elevated in MI/R mice and hypoxia cell models, accompanied by enhanced cell apoptosis. Inhibition of miR-17-5p led to decreased apoptosis related to ER stress response in the hypoxia model, which could be counteracted by knockdown of Tsg101 (tumor susceptibility gene 101). Transfection with miR-17-5p mimics downregulated the expression of Tsg101 in H9c2 cells. Luciferase assay demonstrated the binding between miR-17-5p and Tsg101. Moreover, 4-PBA, the inhibitor of the ER stress response, abolished shTsg101 elevated apoptosis in hypoxic H9c2 cells. Our findings investigated the pro-apoptotic role of miR-17-5p during MI/R, disclosed the specific mechanism of miR-17-5p/Tsg101 regulatory axis in ER stress-induced myocardium injury and cardiomyocytes apoptosis, and presented a promising diagnostic biomarker and potential target for therapy of AMI.

心血管疾病是全球死亡的主要原因，其中急性心肌梗死（AMI）常发生在心脏，由心肌缺血和内质网（ER）应激诱导的细胞死亡引起。大量关于 miRNA 的研究表明它们作为心脏病诊断生物标志物和治疗靶点的潜力。我们的研究调查了 AMI 期间 miR-17-5p 的作用及其调节机制。超声心动图、MTT、流式细胞术、caspase-3 和乳酸脱氢酶 (LDH) 活性评估分别评估 MI/R 小鼠模型和 H ₂ O ₂诱导的 H9c2 缺氧细胞模型的细胞活力和细胞凋亡。使用 qRT-PCR、IHC 和蛋白质印迹法检测 ER 应激反应相关生物标志物的表达水平。通过生物信息学预测和荧光素酶报告基因测定确定 miR-17-5p 在 Tsg101 mRNA 上的结合位点。 MI/R 小鼠和缺氧细胞模型中 miR-17-5p 的表达水平显着升高，并伴有细胞凋亡增强。抑制 miR-17-5p 会导致缺氧模型中与 ER 应激反应相关的细胞凋亡减少，这可以通过敲低 Tsg101（肿瘤易感基因 101）来抵消。转染 miR-17-5p 模拟下调 H9c2 细胞中 Tsg101 的表达。荧光素酶测定证明了 miR-17-5p 和 Tsg101 之间的结合。此外，4-PBA（ER 应激反应抑制剂）消除了 shTsg101 促进缺氧 H9c2 细胞凋亡的作用。 我们的研究结果探讨了 miR-17-5p 在 MI/R 过程中的促凋亡作用，揭示了 miR-17-5p/Tsg101 调节轴在内质网应激诱导的心肌损伤和心肌细胞凋亡中的具体机制，并提出了一种有前景的诊断生物标志物以及 AMI 治疗的潜在靶点。