MALAT1/miR‐185‐5p mediated high glucose‐induced oxidative stress, mitochondrial injury and cardiomyocyte apoptosis via the RhoA/ROCK pathway

Abstract To explore the underlying mechanism of lncRNA MALAT1 in the pathogenesis of diabetic cardiomyopathy (DCM). DCM models were confirmed in db/db mice. MiRNAs in myocardium were detected by miRNA sequencing. The interactions of miR‐185‐5p with MALAT1 and RhoA were validated by dual‐luciferase reporter assays. Primary neonatal cardiomyocytes were cultured with 5.5 or 30 mmol/L D‐glucose (HG) in the presence or absence of MALAT1‐shRNA and fasudil, a ROCK inhibitor. MALAT1 and miR‐185‐5p expression were determined by real‐time quantitative PCR. The apoptotic cardiomyocytes were evaluated using flow cytometry and TUNEL staining. SOD activity and MDA contents were measured. The ROCK activity, phosphorylation of Drp1 S616 , mitofusin 2 and apoptosis‐related proteins were analysed by Western blotting. Mitochondrial membrane potential was examined by JC‐1. MALAT1 was significantly up‐regulated while miR‐185‐5p was down‐regulated in myocardium of db/db mice and HG‐induced cardiomyocytes. MALAT1 regulated RhoA/ROCK pathway via sponging miR‐185‐5p in cardiomyocytes in HG. Knockdown of MALAT1 and fasudil all inhibited HG‐induced oxidative stress, and alleviated imbalance of mitochondrial dynamics and mitochondrial dysfunction, accompanied by reduced cardiomyocyte apoptosis. MALAT1 activated the RhoA/ROCK pathway via sponging miR‐185‐5p and mediated HG‐induced oxidative stress, mitochondrial damage and apoptosis of cardiomyocytes in mice.