Distinct sources and effects of mitochondrial reactive oxygen species.

Mitochondrial reactive oxygen species (mtROS) have been implicated in aging and disease for decades and are typically viewed as a unitary, non-specific oxidative burden on cells and tissues. However, recent studies have identified at least eleven individual sources of mitochondrial ROS (ISOMRs) and revealed that ISOMRs have distinct, dynamic, and often reversible roles in diverse physiological and pathological processes, including neurodegenerative diseases, immune and metabolic dysregulation, and ischemia-reperfusion injury. This review describes the upstream molecular events that control ISOMR activity, recently developed tools for studying mtROS in general and ISOMRs more specifically, and the evolving perspectives on ISOMR roles in context-specific cell signaling. Future studies to define predictive principles of ISOMR regulation are necessary to open frontiers of redox biology and identify therapeutic strategies for selective modulation of ISOMR-dependent mechanisms in aging and disease.