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Making ROS for apoptosis

p66Shc reduces cytochrome c and generates hydrogen peroxide. GIORGIO/ELSEVIER

Reactive oxygen species (ROS) are not all accidental and unwanted byproducts. Marco Giorgio, Enrica Migliaccio, Pier Giuseppe Pelicci (University of Milan, Italy), and colleagues report that a protein called p66^Shc purposely siphons electrons from the respiratory chain and uses them to trigger apoptosis during times of stress.

Cells that lack p66^Shc were known to produce less ROS and be resistant to various pro-apoptosis stimuli. Giorgio et al. now show that p66^Shc is sufficient to induce mitochondrial swelling and rupture when added to purified mitochondria. The protein also induces excess ROS production, but only when the organelles are undergoing respiration.p66^Shc takes electrons from the respiratory protein cytochrome c and uses them to produce the ROS hydrogen peroxide. p66^Shc diverts only a fraction of the electrons though, and respiration continues in its presence.

Because hydrogen peroxide can diffuse through the mitochondria and open holes in the membrane, p66^Shc's redirection of electrons must somehow be regulated to prevent unwanted apoptosis. p66^Shc increases production of ROS during times of stress, when cellular damage might be too extensive to repair. But just how the cell limits p66^Shc activity during healthy times is not yet clear.

Reference:

Giorgio, M., et al. 2005. Cell. 122:221–233.[CrossRef][Medline]

Rabiya S. Tuma

rabiya{at}nasw.org

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This Article Full Text (PDF, 419K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Tuma, R. S. Search for Related Content PubMed Articles by Tuma, R. S. Social Bookmarking                            What's this?