Ischemic dilated cardiomyopathy pathophysiology through microRNA-16-5p

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• Cellular Stress Response

Background:

• MicroRNA-16-5p (miR-16) is upregulated in ischemic cardiomyopathy (iCM) and contributes to myocardial apoptosis.
• Investigating miR-16's role in endoplasmic reticulum (ER) stress and autophagy is crucial for understanding the apoptotic iCM environment.

Purpose of the Study:

• To determine the specific association of miR-16 with ischemic dilated cardiomyopathy (iDCM).
• To elucidate the role of miR-16 in ER stress, autophagy, and apoptosis in iDCM.

Main Methods:

• Quantitative real-time PCR measured plasma miR-16 levels in 168 participants (controls, iDCM, familial DCM).
• In vitro studies analyzed miR-16 overexpression effects on apoptosis, cell viability, ER stress markers (PERK/CHOP), and autophagic flux in human cardiac cells.

Main Results:

• Plasma miR-16 levels were significantly higher in iDCM patients (P=.039) and associated with clinical variables (P <.001).
• In vitro, miR-16 overexpression increased apoptosis (P=.02), reduced cell viability (P=.008), and induced ER stress via the PERK/CHOP pathway.
• miR-16 also augmented autophagic flux (P <.001) without lysosomal blockade, suggesting a cytoprotective role.

Conclusions:

• MiR-16 is specifically linked to iDCM.
• In ischemic conditions, miR-16 triggers ER stress and inflammation, subsequently activating autophagy in cardiac cells.
• Autophagy appears to be a cellular defense mechanism to maintain homeostasis against ER stress-induced protein aggregation before apoptosis occurs.