Bax directly induces release of cytochrome c from isolated mitochondria
Juliane M. Jürgensmeier,Zhihua Xie,Quinn Deveraux,Lisa M. Ellerby,Dale E. Bredesen,John C. Reed +5 more
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TLDR
It is shown that addition of submicromolar amounts of recombinant Bax protein to isolated mitochondria can induce cytochrome c (Cyt c) release, whereas a peptide representing the Bax BH3 domain was inactive, implying that Bax uses an alternative mechanism for triggering release of Cyt c from mitochondria.Abstract:
Bax is a pro-apoptotic member of the Bcl-2 protein family that resides in the outer mitochondrial membrane. It is controversial whether Bax promotes cell death directly through its putative function as a channel protein versus indirectly by inhibiting cellular regulators of the cell death proteases (caspases). We show here that addition of submicromolar amounts of recombinant Bax protein to isolated mitochondria can induce cytochrome c (Cyt c) release, whereas a peptide representing the Bax BH3 domain was inactive. When placed into purified cytosol, neither mitochondria nor Bax individually induced proteolytic processing and activation of caspases. In contrast, the combination of Bax and mitochondria triggered release of Cyt c from mitochondria and induced caspase activation in cytosols. Supernatants from Bax-treated mitochondria also induced caspase processing and activation. Recombinant Bcl-XL protein abrogated Bax-induced release of Cyt c from isolated mitochondria and prevented caspase activation. In contrast, the broad-specificity caspase inhibitor benzyloxycarbonyl-valinyl-alaninyl-aspartyl-(0-methyl)-fluoromethylketone (zVAD-fmk) and the caspase-inhibiting protein X-IAP had no effect on Bax-induced release of Cyt c from mitochondria in vitro but prevented the subsequent activation of caspases in cytosolic extracts. Unlike Ca2+, a classical inducer of mitochondrial permeability transition, Bax did not induce swelling of mitochondria in vitro. Because the organellar swelling caused by permeability transition causes outer membrane rupture, the findings, therefore, dissociate these two events, implying that Bax uses an alternative mechanism for triggering release of Cyt c from mitochondria.read more
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Mitochondria and apoptosis
Douglas R. Green,John C. Reed +1 more
TL;DR: A variety of key events in apoptosis focus on mitochondria, including the release of caspase activators (such as cytochrome c), changes in electron transport, loss of mitochondrial transmembrane potential, altered cellular oxidation-reduction, and participation of pro- and antiapoptotic Bcl-2 family proteins.
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The BCL-2 protein family: opposing activities that mediate cell death
TL;DR: New insights into interactions among BCL-2 family proteins reveal how these proteins are regulated, but a unifying hypothesis for the mechanisms they use to activate caspases remains elusive.
Journal ArticleDOI
Bid, a Bcl2 Interacting Protein, Mediates Cytochrome c Release from Mitochondria in Response to Activation of Cell Surface Death Receptors
TL;DR: The purification of a cytosolic protein that induces cytochrome c release from mitochondria in response to caspase-8, the apical caspases activated by cell surface death receptors such as Fas and TNF is reported.
Journal ArticleDOI
BCL-2 family members and the mitochondria in apoptosis
TL;DR: As the BCL-2 family members reside upstream of irreversible cellular damage and focus much of their efforts at the level of mitochondria, they play a pivotal role in deciding whether a cell will live or die, and it is argued that the amphipathic a-helical BH3 domain serves as a critical death domain in the pro-apoptotic members.
Journal ArticleDOI
Emerging roles of caspase-3 in apoptosis
Alan G. Porter,Reiner U. Jänicke +1 more
TL;DR: Caspase-3 is essential for certain processes associated with the dismantling of the cell and the formation of apoptotic bodies, but it may also function before or at the stage when commitment to loss of cell viability is made.
References
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Induction of apoptotic program in cell-free extracts : requirement for datp and cytochrome c
TL;DR: Cells undergoing apoptosis in vivo showed increased release of cy tochrome c to their cytosol, suggesting that mitochondria may function in apoptosis by releasing cytochrome c.
Journal ArticleDOI
Prevention of Apoptosis by Bcl-2: Release of Cytochrome c from Mitochondria Blocked
Jie Yang,Xuesong Liu,Xuesong Liu,Kapil N. Bhalla,Caryn Naekyung Kim,Ana Maria Ibrado,Jiyang Cai,Tsung I. Peng,Dean P. Jones,Xiaodong Wang,Xiaodong Wang +10 more
TL;DR: One possible role of Bcl-2 in prevention of apoptosis is to block cytochrome c release from mitochondria, which is normally located in the mitochondrial intermembrane space.
Journal ArticleDOI
The Release of Cytochrome c from Mitochondria: A Primary Site for Bcl-2 Regulation of Apoptosis
TL;DR: In a cell-free apoptosis system, mitochondria spontaneously released cytochrome c, which activated DEVD-specific caspases, leading to fodrin cleavage and apoptotic nuclear morphology, and Bcl-2 acts to inhibit cy tochrome c translocation, thereby blocking caspase activation and the apoptotic process.
Journal ArticleDOI
Tumor suppressor p53 is a direct transcriptional activator of the human bax gene
T Miyashita,John C. Reed +1 more
TL;DR: The bax gene promoter region contains four motifs with homology to consensus p53-binding sites and wild-type but not mutant p53 protein bound to oligonucleotides corresponding to this region of the bax promoter, suggesting that bax is a p53 primary-response gene, presumably involved in a p 53-regulated pathway for induction of apoptosis.
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Apaf-1, a Human Protein Homologous to C. elegans CED-4, Participates in Cytochrome c–Dependent Activation of Caspase-3
TL;DR: The purification and cDNA cloning of Apaf-1, a novel 130 kd protein from HeLa cell cytosol that participates in the cytochrome c-dependent activation of caspase-3, leading to apoptosis is reported here.