p53 regulates mitochondrial membrane potential through reactive oxygen species and induces cytochrome c-independent apoptosis blocked by Bcl-2

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Item Type:	Article
Title:	p53 regulates mitochondrial membrane potential through reactive oxygen species and induces cytochrome c-independent apoptosis blocked by Bcl-2
Creators Name:	Li, P.F., Dietz, R. and von Harsdorf, R.
Abstract:	Downstream mediators of p53 in apoptosis induction remain to be elucidated. We report that p53-induced apoptosis occurred in the absence of cytochrome c release into the cytosol. Although Bax was upregulated, it remained largely in the cytosol and there was no detectable translocation to the mitochondria. Bid was not activated as no cleavage could be detected. Thus, the absence of cytochrome c release may be due to the lack of Bax translocation to mitochondria and/or Bid inactivation. Nevertheless, p53-induced apoptosis is still caspase dependent because it could be abolished by z-VAD-fmk. To search for alternative downstream targets of p53, we detected production of reactive oxygen species (ROS) as well as mitochondrial membrane potential (Deltapsi). p53 induced ROS generation, which then caused a transient increase of Deltapsi followed by a decrease. Antioxidants could inhibit the alterations of Deltapsi, thereby preventing apoptosis. z-VAD-fmk was unable to abrogate Deltapsi elevation but inhibited Deltapsi decrease, indicating that Deltapsi elevation and its decrease are two independent events. Bcl-2 may abolish elevation as well as decrease of Deltapsi without interfering with ROS levels. Thus, the ROS-mediated disruption of Deltapsi constitutes a pivotal step in the apoptotic pathway of p53, and this pathway does not involve cytochrome c release.
Keywords:	Amino Acid Chloromethyl Ketones, Antioxidants, Apoptosis, BH3 Interacting Domain Death Agonist Protein, Carbocyanines, Carrier Proteins, Caspases, Cytochrome c Group, Enzyme Activation, Gene Expression Regulation, Hela Cells, Membrane Potentials, Mitochondria, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Reactive Oxygen Species, Signal Transduction, Transfection, Tumor Suppressor Protein p53, bcl-2-Associated X Protein
Source:	EMBO Journal
ISSN:	0261-4189
Publisher:	Oxford University Press
Volume:	18
Number:	21
Page Range:	6027-6036
Date:	1 November 1999
Official Publication:	https://doi.org/10.1093/emboj/18.21.6027
PubMed:	View item in PubMed

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