Cardiac fibroblast miR-27a may function as an endogenous anti-fibrotic by negatively regulating Early Growth Response...

Area of Science:

• Cardiovascular Biology
• Molecular Medicine
• Fibrosis Research

Background:

• Chronic cardiac stress leads to pathological myocardial fibrosis and hypertrophy.
• MicroRNA-27a (miR-27a) is known to regulate collagen production and inhibit fibrosis.
• The specific role of miR-27a in cardiac hypertrophy and remodeling remains less understood.

Purpose of the Study:

• To investigate the in vivo effects of miR-27a on cardiac remodeling and fibrosis.
• To elucidate the molecular mechanisms by which miR-27a influences cardiac fibroblasts.
• To identify miR-27a's direct targets involved in cardiac fibrosis.

Main Methods:

• Utilized a transverse aortic constriction (TAC) murine model for left ventricular pressure overload.
• Employed genetic miR-27a knockout, antisense inhibition, and fibroblast-specific modulation in vivo.
• Performed in silico Venn analysis and reporter assays to identify miR-27a-5p targets, specifically Early Growth Response Protein 3 (Egr3).
• Evaluated the impact of miR-27a-5p and Egr3 on transforming growth factor-beta (Tgf-β) signaling and cardiac fibroblast secretome in vitro.

Main Results:

• miR-27a-5p significantly attenuated TAC-induced cardiac fibrosis and myofibroblast activation.
• No discernible effect of miR-27a-5p was observed on cardiac myocytes.
• miR-27a-5p inhibited Tgf-β signaling and pro-fibrotic protein secretion in cardiac fibroblasts by suppressing Egr3.
• Identified Egr3 as a direct target of miR-27a-5p.

Conclusions:

• Cardiac fibroblast miR-27a acts as an endogenous anti-fibrotic agent.
• miR-27a negatively regulates Egr3 expression in cardiac fibroblasts.
• This mechanism highlights miR-27a as a potential therapeutic target for mitigating cardiac fibrosis.