Mitochondrial UQCRC2 as a Redox-Regulatory Node in Metabolic and Cardiometabolic Diseases

Metabolic and cardiometabolic diseases are closely associated with mitochondrial dysfunction and redox imbalance. Ubiquinol–cytochrome c reductase core protein 2 (UQCRC2), a non-catalytic structural core subunit of mitochondrial respiratory chain Complex III, is increasingly recognized as a regulator of Complex III integrity, electron transfer, oxidative phosphorylation, and mitochondrial redox homeostasis. Under metabolic stress, reduced expression or functional impairment of UQCRC2 may promote electron leakage, mitochondrial reactive oxygen species (mtROS) generation, lipid peroxidation, impaired antioxidant defense, and disrupted glucose–lipid metabolism. These alterations may contribute to insulin resistance (IR), metabolic dysfunction-associated steatotic liver disease (MASLD), obesity, and cardiovascular disease (CVD). This review summarizes current evidence linking UQCRC2 dysfunction to mitochondrial bioenergetic failure, oxidative stress, inflammatory signaling, and cardiometabolic injury. We further discuss redox-regulatory pathways, including Nrf2, AMPK–SIRT1–PGC-1α, glutathione metabolism, and mitophagy, as well as pharmacological agents and natural compounds that may modulate UQCRC2-related mitochondrial responses. Collectively, these findings highlight UQCRC2 as a redox-sensitive mitochondrial node linking Complex III dysfunction to cardiometabolic injury and targeted redox-based interventions.