MCU Up-regulation contributes to myocardial ischemia-reperfusion Injury through calpain/OPA-1-mediated mitochondrial...

Area of Science:

• Cardiovascular Research
• Mitochondrial Biology
• Cellular Physiology

Background:

• Mitochondrial dynamics are crucial for cellular health and are implicated in myocardial ischemia/reperfusion (I/R) injury.
• Disruptions in mitochondrial fission, fusion, and mitophagy contribute to I/R-induced damage.

Purpose of the Study:

• To investigate the role of the mitochondrial calcium uniporter (MCU) in mitochondrial dynamic imbalance during myocardial I/R.
• To elucidate the signaling pathways linking MCU to mitochondrial dysfunction and cardiomyocyte apoptosis.

Main Methods:

• Established mouse myocardial I/R and cardiomyocyte hypoxia/reoxygenation (H/R) models.
• Utilized MCU inhibitor (Ru360) and enhancer (spermine) to modulate MCU function.
• Investigated calpain-1/2 and Optic atrophy type 1 (OPA1) expression and activation.
• Employed transgenic mice overexpressing calpastatin and siRNA for OPA1 knockdown.

Main Results:

• MCU expression and activity increased during I/R, correlating with myocardial injury, increased fission, and reduced fusion and mitophagy.
• Inhibition of MCU protected against I/R injury, reducing infarct size and apoptosis, and restoring mitochondrial dynamics.
• Enhanced MCU function exacerbated injury and mitochondrial imbalance.
• MCU upregulation promoted calpain-1/2 activation and OPA1 downregulation.
• Calpain inhibition or OPA1 restoration ameliorated I/R-induced mitochondrial dysfunction and apoptosis.

Conclusions:

• MCU upregulation during I/R triggers a pathway involving calpain activation and OPA1 downregulation, leading to mitochondrial dynamic imbalance.
• Targeting MCU or its downstream effectors (calpains, OPA1) represents a potential therapeutic strategy for myocardial I/R injury.