Oxidative insults disrupt OPA1-mediated mitochondrial dynamics in cultured mammalian cells.

OBJECTIVE

To explore the impact of oxidative insults on mitochondrial dynamics. In mammalian cells, oxidative insults activate stress response pathways including inflammation, cytokine secretion, and apoptosis. Intriguingly, mitochondria are emerging as a sensitive network that may function as an early indicator of subsequent cellular stress responses. Mitochondria form a dynamic network, balancing fusion, mediated by optic atrophy-1 (OPA1), and fission events, mediated by dynamin-related protein-1 (DRP1), to maintain homeostasis.

METHODS

Here, we examine the impact of oxidative insults on mitochondrial dynamics in 143B osteosarcoma and H9c2 cardiomyoblast cell lines via confocal microscopy, flow cytometry, and protein-based analyses.

RESULTS

When challenged with hydrogen peroxide (H2O2), a ROS donor, both cell lines display fragmentation of the mitochondrial network and loss of fusion-active OPA1 isoforms, indicating that OPA1-mediated mitochondrial fusion is disrupted by oxidative damage in mammalian cells. Consistent with this, cells lacking OMA1, a key protease responsible for cleavage of OPA1, are protected against OPA1 cleavage and mitochondrial fragmentation in response to H2O2 challenge.

DISCUSSION: Taken together, these findings indicate that oxidative insults damage OPA1-mediated mitochondrial dynamics in mammalian cells via activation of OMA1, consistent with an emerging role for mitochondrial dynamics as an early indicator of cellular stress signaling.