FIG. 7.

Regulation of mitochondrial morphology and OXPHOS by Trolox-sensitive endogenous signaling reactive oxygen species (sROS). Trolox reduces the levels of endogenous CM-H₂DCF oxidizing signaling ROS (sROS) but not HEt oxidizing sROS in a glutathione (GSH)-dependent manner. This leads to increased levels of mitochondria-attached mitofusins and ensuing mitochondrial filamentation. The latter is associated with increased OXPHOS activity, O₂ consumption, and sarcoplasmatic-endoplasmatic reticulum Ca²⁺ ATPase (SERCA) action, thereby affecting cellular calcium handling (see Discussion for details).