Mitochondrial Hydrogen Peroxide as a Redox Signal

Mitochondria are at the heart of cell metabolism and contribute to many aspects of the life and death of the cell. Mitochondria are the site of oxidative phosphorylation; consequently, they are the major source of ATP in most eukaryotic cells and hence any defects to these processes impact cell survival. The metabolic pathways, notably Krebs cycle and fatty acid oxidation, that provide electrons to the respiratory chain are vital for oxidative phosphorylation, but they affect many other processes beyond the supply of ATP. The many roles carried out by the mitochondrion are closely integrated into the function of the cell. Mitochondria can generate superoxide within the matrix from a number of sources, and this superoxide is then dismutated to H₂O₂ by the high concentration of MnSOD present. For H₂O₂ itself to act as a redox signal it has to leave the mitochondria and enter the cytosol.