Long Noncoding RNA H19 Overexpression Inhibits High Glucose-Induced Oxidative Stress of Cardiomyocytes by Targeting MicroRNA-138-5p/MCU Axis: Implications for Diabetic Cardiomyopathy.

This study investigates the regulatory effects of long non-coding RNA H19 on miR-138-5p and their collective impact on mitochondrial oxidative stress injury in high glucose-exposed cardiomyocytes, while elucidating the underlying molecular mechanisms. The findings aim to establish a theoretical foundation for understanding the pathogenesis of diabetic cardiomyopathy. The expression levels of lncRNA H19, miR-138-5p, and MCU were quantified using RT-qPCR. H9c2 cardiomyocytes were exposed to high glucose (HG, 33 mM) in vitro to establish a diabetic cardiomyopathy (DCM) model. Regulatory targeting relationships between lncRNA H19 and miR-138-5p, as well as between miR-138-5p and mitochondrial calcium uniporter(MCU), were confirmed through dual-luciferase reporter assays. Levels of reactive oxygen species (ROS), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content were quantified to evaluate intracellular oxidative stress in cardiomyocytes. MCU protein expression was analyzed by western blotting. In DCM, H19 and MCU were downregulated; miR-138-5p was upregulated. H19 overexpression increased SOD activity and reduced ROS and MDA levels in HG-treated H9c2 cardiomyocytes. Dual-luciferase assays validated miR-138-5p binding to H19 and MCU 3'UTRs. miR-138-5p overexpression suppressed MCU protein expression. Rescue experiments demonstrated miR-138-5p overexpression or MCU silencing reversed H19-mediated oxidative stress attenuation in HG-stimulated cells. Overexpression of H19 attenuates oxidative stress by modulating the miR-138-5p/MCU axis in DCM, highlighting its potential as a diagnostic biomarker and/or therapeutic target for this condition.