Apoptosis and cytochrome c release in cerebellar granule cells.

In the light of both the major role played by released cytochrome c in apoptosis of a variety of cells and the availability of cerebellar granule cells as a model system to investigate apoptosis as a function of time from induction to cell death, we review data aimed at elucidating the events dealing with cytochrome c release from mitochondria as well as its role outside mitochondria. We report cytochrome c release in the apoptosis time course as dependent on the function of both the antioxidant and proteolytic systems. We show that, beside the role played by cytochrome c in participating in apoptosome formation and in triggering the caspase cascade, at least in cerebellar granule cells, released cytochrome c can maintain its ability to work as an electron carrier, being a scavenger of reactive oxygen species and an electron donor to cytochrome oxidase, thus driving the ATP synthesis.