Mitochondrial Quality Control in Health and Disease.

Mitochondria are central regulators of cellular energy metabolism, and their functional integrity is essential for maintaining cellular homeostasis. Mitochondrial quality control (MQC) encompasses a coordinated network of mitochondrial biogenesis, dynamics (fusion and fission), and selective autophagy (mitophagy), which together sustain mitochondrial structure and function. Under physiological conditions, MQC ensures the removal of dysfunctional mitochondria, restricts excessive reactive oxygen species production, and modulates apoptosis, thereby supporting the high energy demands of organs such as the heart and brain. Disruption of MQC contributes to the onset and progression of various diseases, including neurodegenerative disorders, cardiovascular pathologies, and metabolic syndromes, largely through accumulation of damaged mitochondria and impaired metabolic signaling. While the core components of MQC have been characterized, the mechanistic interplay among its modules and their disease-specific alterations remain incompletely defined. This review provides an integrated overview of the molecular pathways governing mitochondrial biogenesis, dynamics, and mitophagy, with a focus on their cross-talk in maintaining mitochondrial homeostasis. We further discuss how MQC dysfunction contributes to disease pathogenesis and examine emerging therapeutic approaches aimed at restoring mitochondrial quality. Understanding the regulatory logic of MQC not only elucidates fundamental principles of cellular stress adaptation but also informs novel strategies for disease intervention.