Cytochrome c is rapidly reduced in the cytosol after mitochondrial outer membrane permeabilization

Ripple, Maureen O.; Abajian, Michelle; Springett, Roger

doi:10.1007/s10495-010-0455-2

Cited by 50 publications

(34 citation statements)

References 31 publications

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“…We observed significantly lower levels of mitochondrial Cyt c in the LS12 cells compared to the parental cell line (0.28±0.15, p =0.01), validating the observations of Nagar et al that Cyt c is being released into the cytosol [31]. These observations are also supported by Ripple et al, who demonstrated that the mitochondrial concentration of Cyt c is decreased and the cytosolic concentration of Cyt c is increased when Cyt c is effluxed out of the mitochondria [34]. …”

Section: Resultssupporting

confidence: 84%

Quantitative proteomic analysis of mitochondrial proteins reveals prosurvival mechanisms in the perpetuation of radiation-induced genomic instability

Thomas

Waters

Morgan

et al. 2012

Free Radical Biology and Medicine

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Radiation-induced genomic instability is a well-studied phenomenon that is measured as mitotically heritable genetic alterations observed in the progeny of an irradiated cell. The mechanisms that perpetuate this instability are unclear; however, a role for chronic oxidative stress has consistently been demonstrated. In the chromosomally unstable LS12 cell line, oxidative stress and genomic instability were correlated with mitochondrial dysfunction. To clarify this mitochondrial dysfunction and gain insight into the mechanisms underlying radiation-induced genomic instability we have evaluated the mitochondrial subproteome and performed quantitative mass spectrometry analysis of LS12 cells. Of 98 quantified mitochondrial proteins, 17 met criteria for fold changes and reproducibility; and 11 were statistically significant in comparison with the stable parental GM10115 cell line. Previous observations implicated defects in the electron transport chain (ETC) in the LS12 cell mitochondrial dysfunction. Proteomic analysis supports these observations, demonstrating significantly reduced levels of mitochondrial cytochrome c, the intermediary between complexes III and IV of the ETC. Results also suggest that LS12 cells compensate for ETC dysfunction and oxidative stress through increased levels of tricarboxylic acid cycle enzymes and upregulation of proteins that protect against oxidative stress and apoptosis. More than one cellular defect is likely to contribute to the genomic instability phenotype, and evaluation of gene and microRNA expression suggests that epigenetics play a role in the phenotype. These data suggest that LS12 cells have adapted mechanisms that allow survival under suboptimal conditions of oxidative stress and compromised mitochondrial function to perpetuate genomic instability.

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Section: Resultssupporting

confidence: 84%

Quantitative proteomic analysis of mitochondrial proteins reveals prosurvival mechanisms in the perpetuation of radiation-induced genomic instability

Thomas

Waters

Morgan

et al. 2012

Free Radical Biology and Medicine

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“…Whether the G41T mutation, phosphorylation or nitration of cyt c in vivo will cause adoption of the alkaline conformation is an open question. Following mitochondrial outer membrane permeabilization, the cytosolic cyt c pool has been reported to be fully reduced [50] suggesting there is little relevance to caspase activation in vivo for the alkaline transition per se . However others have suggested that cyt c must be oxidized in order to maximize caspase activation [51].…”

Section: Resultsmentioning

confidence: 99%

Conformational change and human cytochrome c function: mutation of residue 41 modulates caspase activation and destabilizes Met-80 coordination

et al. 2013

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Cytochrome c is a highly conserved protein, with 20 residues identical in all eukaryotic cytochromes c. Glycine 41 is one of these invariant residues, and is the position of the only reported naturally occurring mutation in cytochrome c (human G41S). The basis, if any, for the conservation of Gly-41 is unknown. The mutation of Gly-41 to Ser enhances the apoptotic activity of cytochrome c without altering its role in mitochondrial electron transport. Here we have studied additional residue 41 variants and determined their effects on cytochrome c functions and conformation. A G41T mutation decreased the ability of cytochrome c to induce caspase activation and decreased the redox potential, whereas a G41A mutation had no impact on caspase induction but redox potential increased. All residue 41 variants decreased the pKa of a structural transition of oxidized cytochrome c to the alkaline conformation, and this correlated with a destabilization of the interaction of Met-80 with the heme iron(III) at physiological pH. In reduced cytochrome c the G41T and G41S mutations had distinct effects on a network of hydrogen bonds involving Met-80, and in G41T the conformational mobility of two Ω loops was altered. These results suggest the impact of residue 41 on the conformation of cytochrome c influences its ability to act in both of its physiological roles, electron transport and caspase activation.

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“…To understand how phosphorylation affects the structure of human Cc, we tackled the challenge of fully characterizing the phosphomimetic mutant Y48pCMF Cc in its reduced form, which is the redox state of Cc donating electrons to CcO in homeostasis and is essential for its apoptotic activity, because Cc becomes highly reduced upon its release from the mitochondria to the cytosol (32). Y48pCMF Cc maintains the overall secondary structure and global fold of wild-type (WT) Cc, as inferred from circular dichroism (CD) (Fig.…”

Section: Phosphorylation Of Tyr48 Induces Local Structural Changes Inmentioning

confidence: 99%

Structural basis of mitochondrial dysfunction in response to cytochrome c phosphorylation at tyrosine 48

Moreno‐Beltrán

Guerra‐Castellano

Díaz-Quintana

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Regulation of mitochondrial activity allows cells to adapt to changing conditions and to control oxidative stress, and its dysfunction can lead to hypoxia-dependent pathologies such as ischemia and cancer. Although cytochrome c phosphorylation—in particular, at tyrosine 48—is a key modulator of mitochondrial signaling, its action and molecular basis remain unknown. Here we mimic phosphorylation of cytochrome c by replacing tyrosine 48 with p-carboxy-methyl-l-phenylalanine (pCMF). The NMR structure of the resulting mutant reveals significant conformational shifts and enhanced dynamics around pCMF that could explain changes observed in its functionality: The phosphomimetic mutation impairs cytochrome c diffusion between respiratory complexes, enhances hemeprotein peroxidase and reactive oxygen species scavenging activities, and hinders caspase-dependent apoptosis. Our findings provide a framework to further investigate the modulation of mitochondrial activity by phosphorylated cytochrome c and to develop novel therapeutic approaches based on its prosurvival effects.

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Cytochrome c is rapidly reduced in the cytosol after mitochondrial outer membrane permeabilization

Cited by 50 publications

References 31 publications

Quantitative proteomic analysis of mitochondrial proteins reveals prosurvival mechanisms in the perpetuation of radiation-induced genomic instability

Quantitative proteomic analysis of mitochondrial proteins reveals prosurvival mechanisms in the perpetuation of radiation-induced genomic instability

Conformational change and human cytochrome c function: mutation of residue 41 modulates caspase activation and destabilizes Met-80 coordination

Structural basis of mitochondrial dysfunction in response to cytochrome c phosphorylation at tyrosine 48

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