Unraveling Diabetic Cardiomyopathy (DCM): The Critical Role of the Yap–miR-22-3p–Sirt1 axis in the Pathogenesis of DCM
Background: Diabetic cardiomyopathy (DCM), characterized by myocardial hypertrophy and myocardial fibrosis, is a severe complication of diabetes. Yes-associated protein (Yap) activation contributes to myocardial remodeling and cardiac dysfunction. This study investigated the role of Yap and its molecular mechanism in DCM. Methods: Yap expression was assessed in mice with type 2 diabetes mellitus (T2DM) and high glucose (HG) + insulin-treated neonatal rat cardiomyocytes (NRCMs). Adeno-associated virus transfection, siRNA transfection, and a transgenic mouse model were used to manipulate Yap and sirtuin 1 (Sirt1) expression in vivo and in vitro. RNA sequencing, differential gene analysis, and miRNA sequencing were used to identify downstream targets of Yap and the underlying mechanisms. Functional assays were used to evaluate cardiomyocyte hypertrophy and fibrosis through molecular markers, cell morphology, and echocardiography. Results: Yap expression was increased in HG + insulin-treated NRCMs and in the hearts of mice with T2DM, thereby promoting myocardial hypertrophy and fibrosis. Yap inhibition reduced the cardiomyocyte cross-sectional area, collagen deposition, and the levels of the hypertrophy markers atrial natriuretic peptide and ß-myosin heavy chain. RNA sequencing identified Sirt1 as a downstream target of Yap. Bioinformatic analysis suggested that Yap positively regulates miR-22-3p, which inhibits Sirt1. Yap inhibition increased Sirt1 expression, mitigating myocardial remodeling. Conversely, Sirt1 knockdown reversed the protective effects of Yap inhibition, restoring hypertrophy and fibrosis. Conclusion: Yap promotes DCM progression by increasing miR-22-3p expression and suppressing Sirt1 expression. Targeting the Yap–miR-22-3p–Sirt1 axis might represent a novel therapeutic strategy for DCM, thereby improving myocardial structure and function. Overall design: Primary neonatal rat cardiomyocytes (NRCMs) were isolated from 1–2-day-old neonatal SD rats. In brief, hearts collected from anesthetized neonatal rats were digested with pancreatic enzymes and type II collagenase.To create an in vitro diabetic model, NRCMs were initially cultured in DMEM supplemented with 1% FBS and 1 g/L glucose for 14 h, followed by 48 h of treatment with 33 mM glucose and 100 nM insulin. Yap expression in these cells was manipulated using adenovirus. The cells were categorized into the Ad-Yap shRNA or Ad-Yap WT group under high glucose conditions. The group transfected with Ad-GFP with or without glucose + insulin treatment served as the CON group. Total RNA was extracted from NRCMs using a Trizol reagent kit. We then performed gene expression profiling analysis using data obtained from RNA-seq of adenovirus infected cardiomyocytes. Comparative gene expression profilling analysis of RNA-Seq data for infected cells.