MiR-338-5p ameliorates pathological cardiac hypertrophy by targeting CAMKIIδ

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• MicroRNA Therapeutics

Background:

• Pathological cardiac hypertrophy (PCH) involves cardiomyocyte growth and ventricular thickening, potentially leading to heart failure.
• MicroRNAs (miRNAs) are implicated in the pathogenesis of PCH.

Purpose of the Study:

• To investigate the role of miR-338-5p in PCH.
• To identify the molecular targets and mechanisms underlying miR-338-5p's function in cardiac hypertrophy.

Main Methods:

• Analysis of miR-338-5p expression in human heart failure patients and a mouse model of PCH (transverse aortic constriction - TAC).
• Cardiac function assessment using echocardiography and hemodynamic measurements in TAC mice overexpressing miR-338-5p via rAAV9.
• Identification of CAMKIIδ as a direct target of miR-338-5p using bioinformatics and luciferase reporter assays.
• In vitro experiments using H9c2 cells to assess the effect of miR-338-5p on Ang-II-induced cell enlargement.

Main Results:

• miR-338-5p expression was altered in cardiac tissues of heart failure patients and TAC-induced PCH mice.
• Overexpression of miR-338-5p using rAAV9 significantly ameliorated TAC-induced PCH, reducing heart weight/body weight ratio.
• miR-338-5p improved cardiac contraction and relaxation function in TAC mice.
• CAMKIIδ was confirmed as a direct target of miR-338-5p.
• miR-338-5p-mediated downregulation of CAMKIIδ reversed Ang-II-induced cardiomyocyte enlargement in vitro.

Conclusions:

• Aberrant regulation of miR-338-5p is observed in pathological cardiac hypertrophy.
• The miR-338-5p/CAMKIIδ axis represents a novel molecular mechanism contributing to PCH pathogenesis.
• Modulating miR-338-5p offers a potential therapeutic avenue for treating PCH and preventing heart failure progression.