Mitochondrial regulation of cellular senescence heterogeneity.

Cellular senescence is a stable cell-cycle arrest program accompanied by extensive metabolic remodeling and acquisition of a senescence-associated secretory phenotype (SASP). Emerging evidence indicates that senescence is not a uniform endpoint but a heterogeneous spectrum of cell states shaped by the nature of the initiating stimulus. Mitochondria have recently emerged as central regulators of this heterogeneity by integrating metabolic, redox, and inflammatory signaling. Senescent cells share common mitochondrial features-including increased mitochondrial mass, elevated reactive oxygen species (ROS), impaired mitophagy, and altered metabolic programs-yet distinct senescence subtypes exhibit unique mitochondrial adaptations. Replicative senescence is governed by a telomere-mitochondria feedback loop, whereas stress- and oncogene-induced senescence involve rapid mitochondrial stress responses and stimulus-specific metabolic rewiring. Therapy-induced senescence further introduces context-dependent mitochondrial dependencies that influence therapeutic resistance and senolytic vulnerability. In this review, we synthesize current understanding of mitochondrial regulation across senescence subtypes and highlight how mitochondrial dysfunction actively drives senescence heterogeneity. We further discuss emerging therapeutic strategies that exploit mitochondrial vulnerabilities to selectively modulate or eliminate senescent cells. Understanding mitochondrial control of senescence heterogeneity provides a conceptual framework for developing precision interventions in aging and cancer.