scholarly journals Identification of a Novel Protein MICS1 that is Involved in Maintenance of Mitochondrial Morphology and Apoptotic Release of Cytochrome c

2008 ◽  
Vol 19 (6) ◽  
pp. 2597-2608 ◽  
Author(s):  
Toshihiko Oka ◽  
Tomoko Sayano ◽  
Shoko Tamai ◽  
Sadaki Yokota ◽  
Hiroki Kato ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Morphological Changes ◽  
Mitochondrial Protein ◽  
Membrane Integrity ◽  
Mitochondrial Morphology ◽  
Cytochrome C Release ◽  
Down Regulation ◽  
Inner Membrane ◽  
Inner Membrane Protein ◽  
Tight Association

Mitochondrial morphology dynamically changes in a balance of membrane fusion and fission in response to the environment, cell cycle, and apoptotic stimuli. Here, we report that a novel mitochondrial protein, MICS1, is involved in mitochondrial morphology in specific cristae structures and the apoptotic release of cytochrome c from the mitochondria. MICS1 is an inner membrane protein with a cleavable presequence and multiple transmembrane segments and belongs to the Bi-1 super family. MICS1 down-regulation causes mitochondrial fragmentation and cristae disorganization and stimulates the release of proapoptotic proteins. Expression of the anti-apoptotic protein Bcl-XL does not prevent morphological changes of mitochondria caused by MICS1 down-regulation, indicating that MICS1 plays a role in maintaining mitochondrial morphology separately from the function in apoptotic pathways. MICS1 overproduction induces mitochondrial aggregation and partially inhibits cytochrome c release during apoptosis, regardless of the occurrence of Bax targeting. MICS1 is cross-linked to cytochrome c without disrupting membrane integrity. Thus, MICS1 facilitates the tight association of cytochrome c with the inner membrane. Furthermore, under low-serum condition, the delay in apoptotic release of cytochrome c correlates with MICS1 up-regulation without significant changes in mitochondrial morphology, suggesting that MICS1 individually functions in mitochondrial morphology and cytochrome c release.

scholarly journals Intramitochondrial sorting of the precursor to yeast cytochrome c oxidase subunit Va.

1993 ◽  
Vol 121 (5) ◽  
pp. 1021-1029 ◽  
Author(s):  
B R Miller ◽  
M G Cumsky
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mitochondrial Protein ◽  
Inner Membrane ◽  
Oxidase Subunit ◽  
Mitochondrial Inner Membrane ◽  
The Matrix ◽  
Inner Membrane Protein ◽  
Membrane Spanning ◽  
Mitochondrial Heat Shock Protein

We have continued our studies on the import pathway of the precursor to yeast cytochrome c oxidase subunit Va (pVa), a mitochondrial inner membrane protein. Previous work on this precursor demonstrated that import of pVa is unusually efficient, and that inner membrane localization is directed by a membrane-spanning domain in the COOH-terminal third of the protein. Here we report the results of studies aimed at analyzing the intramitochondrial sorting of pVa, as well as the role played by ancillary factors in import and localization of the precursor. We found that pVa was efficiently imported and correctly sorted in mitochondria prepared from yeast strains defective in the function of either mitochondrial heat shock protein (hsp)60 or hsp70. Under identical conditions the import and sorting of another mitochondrial protein, the precursor to the beta subunit of the F1 ATPase, was completely defective. Consistent with previous results demonstrating that the subunit Va precursor is loosely folded, we found that pVa could be efficiently imported into mitochondria after translation in wheat germ extracts. This results suggests that normal levels of extramitochondrial hsp70 are also not required for import of the protein. The results of this study enhance our understanding of the mechanism by which pVa is routed to the mitochondrial inner membrane. They suggest that while the NH2 terminus of pVa is exposed to the matrix and processed by the matrix metalloprotease, the protein remains anchored to the inner membrane before being assembled into a functional holoenzyme complex.

scholarly journals Preservation of Mitochondrial Structure and Function after Bid- or Bax-Mediated Cytochrome c Release

2000 ◽  
Vol 150 (5) ◽  
pp. 1027-1036 ◽  
Author(s):  
Oliver von Ahsen ◽  
Christian Renken ◽  
Guy Perkins ◽  
Ruth M. Kluck ◽  
Ella Bossy-Wetzel ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Protein Import ◽  
Mitochondrial Protein ◽  
Intermembrane Space ◽  
Caspase Activation ◽  
Cytochrome C Release ◽  
Mitochondrial Protein Import ◽  
Inner Membrane ◽  
And Function

Proapoptotic members of the Bcl-2 protein family, including Bid and Bax, can activate apoptosis by directly interacting with mitochondria to cause cytochrome c translocation from the intermembrane space into the cytoplasm, thereby triggering Apaf-1–mediated caspase activation. Under some circumstances, when caspase activation is blocked, cells can recover from cytochrome c translocation; this suggests that apoptotic mitochondria may not always suffer catastrophic damage arising from the process of cytochrome c release. We now show that recombinant Bid and Bax cause complete cytochrome c loss from isolated mitochondria in vitro, but preserve the ultrastructure and protein import function of mitochondria, which depend on inner membrane polarization. We also demonstrate that, if caspases are inhibited, mitochondrial protein import function is retained in UV-irradiated or staurosporine-treated cells, despite the complete translocation of cytochrome c. Thus, Bid and Bax act only on the outer membrane, and lesions in the inner membrane occurring during apoptosis are shown to be secondary caspase-dependent events.

scholarly journals MITOCHONDRIAL BIOGENESIS DURING DIFFERENTIATION OF ARTEMIA SALINA CYSTS

1973 ◽  
Vol 58 (3) ◽  
pp. 643-649 ◽  
Author(s):  
H. Schmitt ◽  
H. Grossfeld ◽  
U. Z. Littauer
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome B ◽  
Mitochondrial Biogenesis ◽  
Brine Shrimp ◽  
Morphological Changes ◽  
Artemia Salina ◽  
Mitochondrial Morphology ◽  
Second Stage ◽  
Two Stages

Mitochondria isolated from cysts of Artemia salina (brine shrimp) were found to be devoid of cristae and to possess a low respiratory capability. Hydration of the cysts induces marked biochemical and morphological changes in the mitochondria. Their biogenesis proceeds in two stages. The first stage is completed within 1 h and is characterized by a rapid increase in the respiratory capability of the mitochondria, their cytochrome oxidase, cytochrome b, cytochrome c and perhaps some morphological changes. In the second stage there is an increase in the protein-synthesizing capacity of the mitochondria as well as striking changes in mitochondrial morphology leading to the formation of cristae.

scholarly journals Nuclear Translocation of Apoptosis-Inducing Factor after Focal Cerebral Ischemia

2004 ◽  
Vol 24 (4) ◽  
pp. 458-466 ◽  
Author(s):  
Nikolaus Plesnila ◽  
Changlian Zhu ◽  
Carsten Culmsee ◽  
Moritz Gröger ◽  
Michael A. Moskowitz ◽  
...  
Keyword(s):  
Cell Death ◽  
Cerebral Ischemia ◽  
Cytochrome C ◽  
Nuclear Translocation ◽  
Focal Cerebral Ischemia ◽  
Mitochondrial Protein ◽  
Neuronal Cell ◽  
Experimental Stroke ◽  
Cytochrome C Release ◽  
Apoptosis Inducing Factor

Signaling cascades associated with apoptosis contribute to cell death after focal cerebral ischemia. Cytochrome c release from mitochondria and the subsequent activation of caspases 9 and 3 are critical steps. Recently, a novel mitochondrial protein, apoptosis-inducing factor (AIF), has been implicated in caspase-independent programmed cell death following its translocation to the nucleus. We, therefore, addressed the question whether AIF also plays a role in cell death after focal cerebral ischemia. We detected AIF relocation from mitochondria to nucleus in primary cultured rat neurons 4 and 8 hours after 4 hours of oxygen/glucose deprivation. In ischemic mouse brain, AIF was detected within the nucleus 1 hour after reperfusion after 45 minutes occlusion of the middle cerebral artery. AIF translocation preceded cell death, occurred before or at the time when cytochrome c was released from mitochondria, and was evident within cells showing apoptosis-related DNA fragmentation. From these findings, we infer that AIF may be involved in neuronal cell death after focal cerebral ischemia and that caspase-independent signaling pathways downstream of mitochondria may play a role in apoptotic-like cell death after experimental stroke.

Nitric Oxide–Induced Apoptosis in Human Leukemic Lines Requires Mitochondrial Lipid Degradation and Cytochrome C Release

Blood ◽  
1999 ◽  
Vol 93 (7) ◽  
pp. 2342-2352 ◽  
Author(s):  
Alexey Ushmorov ◽  
Frank Ratter ◽  
Volker Lehmann ◽  
Wulf Dröge ◽  
Volker Schirrmacher ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cytochrome C ◽  
Mitochondrial Protein ◽  
Jurkat Cells ◽  
Leukemic Cells ◽  
Human Leukemia ◽  
Cytochrome C Release ◽  
Mitochondrial Functions ◽  
Mitochondrial Lipid ◽  
Induced Apoptosis

Abstract We have previously shown that nitric oxide (NO) stimulates apoptosis in different human neoplastic lymphoid cell lines through activation of caspases not only via CD95/CD95L interaction, but also independently of such death receptors. Here we investigated mitochondria-dependent mechanisms of NO-induced apoptosis in Jurkat leukemic cells. NO donor glycerol trinitrate (at the concentration, which induces apoptotic cell death) caused (1) a significant decrease in the concentration of cardiolipin, a major mitochondrial lipid; (2) a downregulation in respiratory chain complex activities; (3) a release of the mitochondrial protein cytochrome c into the cytosol; and (4) an activation of caspase-9 and caspase-3. These changes were accompanied by an increase in the number of cells with low mitochondrial transmembrane potential and with a high level of reactive oxygen species production. Higher resistance of the CD95-resistant Jurkat subclone (APO-R) cells to NO-mediated apoptosis correlated with the absence of cytochrome c release and with less alterations in other mitochondrial parameters. An inhibitor of lipid peroxidation, trolox, significantly suppressed NO-mediated apoptosis in APO-S Jurkat cells, whereas bongkrekic acid (BA), which blocks mitochondrial permeability transition, provided only a moderate antiapoptotic effect. Transfection of Jurkat cells with bcl-2 led to a complete block of apoptosis due to the prevention of changes in mitochondrial functions. We suggest that the mitochondrial damage (in particular, cardiolipin degradation and cytochrome c release) induced by NO in human leukemia cells plays a crucial role in the subsequent activation of caspase and apoptosis.

scholarly journals SMS1, a high-copy suppressor of the yeast mas6 mutant, encodes an essential inner membrane protein required for mitochondrial protein import.

1994 ◽  
Vol 5 (5) ◽  
pp. 529-538 ◽  
Author(s):  
K R Ryan ◽  
M M Menold ◽  
S Garrett ◽  
R E Jensen
Keyword(s):  
Membrane Protein ◽  
Protein Import ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Import ◽  
Yeast Saccharomyces Cerevisiae ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Inner Membrane Protein ◽  
Membrane Spanning ◽  
Membrane Spanning Domains

MAS6 encodes an essential inner membrane protein required for mitochondrial protein import in the yeast Saccharomyces cerevisiae (Emtage and Jensen, 1993). To identify new inner membrane import components, we isolated a high-copy suppressor (SMS1) of the mas6-1 mutant. SMS1 encodes a 16.5-kDa protein that contains several potential membrane-spanning domains. The Sms1 protein is homologous to the carboxyl-terminal domain of the Mas6 protein. Like Mas6p, Sms1p is located in the mitochondrial inner membrane and is an essential protein. Depletion of Sms1p from cells causes defects in the import of several mitochondrial precursor proteins, suggesting that Sms1p is a new inner membrane import component. Our observations raise the possibility that Sms1p and Mas6p act together to translocate proteins across the inner membrane.

scholarly journals A mitochondrial-focused genetic interaction map reveals a scaffold-like complex required for inner membrane organization in mitochondria

2011 ◽  
Vol 195 (2) ◽  
pp. 323-340 ◽  
Author(s):  
Suzanne Hoppins ◽  
Sean R. Collins ◽  
Ann Cassidy-Stone ◽  
Eric Hummel ◽  
Rachel M. DeVay ◽  
...  
Keyword(s):  
Genetic Interaction ◽  
Skeletal Structure ◽  
Mitochondrial Morphology ◽  
Functional Connection ◽  
Inner Membrane ◽  
Cellular Pathways ◽  
Inner Membrane Protein ◽  
Interaction Map ◽  
Membrane Components ◽  
And Function

To broadly explore mitochondrial structure and function as well as the communication of mitochondria with other cellular pathways, we constructed a quantitative, high-density genetic interaction map (the MITO-MAP) in Saccharomyces cerevisiae. The MITO-MAP provides a comprehensive view of mitochondrial function including insights into the activity of uncharacterized mitochondrial proteins and the functional connection between mitochondria and the ER. The MITO-MAP also reveals a large inner membrane–associated complex, which we term MitOS for mitochondrial organizing structure, comprised of Fcj1/Mitofilin, a conserved inner membrane protein, and five additional components. MitOS physically and functionally interacts with both outer and inner membrane components and localizes to extended structures that wrap around the inner membrane. We show that MitOS acts in concert with ATP synthase dimers to organize the inner membrane and promote normal mitochondrial morphology. We propose that MitOS acts as a conserved mitochondrial skeletal structure that differentiates regions of the inner membrane to establish the normal internal architecture of mitochondria.

Cardiac mitochondrial cGMP stimulates cytochrome c release

2006 ◽  
Vol 112 (2) ◽  
pp. 113-121 ◽  
Author(s):  
Kazuhiko Seya ◽  
Shigeru Motomura ◽  
Ken-Ichi Furukawa
Keyword(s):  
Cytochrome C ◽  
Mitochondrial Permeability Transition ◽  
Mitochondrial Protein ◽  
Left Ventricular ◽  
Cgmp Level ◽  
Dependent Manner ◽  
Cardiac Mitochondria ◽  
Cytochrome C Release ◽  
Independent Manner ◽  
Rat Cardiomyocytes

Although the existence of cardiac mitochondrial cGMP has been reported previously [Kimura and Murad (1974) J. Biol. Chem. 249, 6910–6916], the physiological and pathophysiological properties of cGMP in cardiac mitochondria have remained unknown. The aim of the present study was to clarify whether cardiac mitochondrial cGMP regulates the apoptosis of cardiomyocytes. In the presence of GTP, the NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine; 1 mmol/l) and SNP (sodium nitroprusside; 1 mmol/l) each markedly increased the cGMP level in a highly purified mitochondrial protein fraction prepared from left ventricular myocytes of male Wistar rats, and these increases were inhibited by 1 μmol/l ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), an inhibitor of NO-sensitive guanylate cyclase. In purified mitochondria, both SNAP (1 mmol/l) and the membrane-permeant cGMP analogue 8-Br-cGMP (8-bromo-cGMP; 1 mmol/l), but not cGMP (1 mmol/l), increased cytochrome c release from succinate-energized mitochondria without inducing mitochondrial swelling and depolarization of the mitochondrial membrane as factors of activation of MPT (mitochondrial permeability transition). The cytochrome c release mediated by SNAP was inhibited in the presence of 1 μmol/l ODQ. On the other hand, 1 mmol/l SNAP induced apoptosis in primary cultured adult rat cardiomyocytes in a time-dependent manner, and this induction was significantly inhibited in the presence of ODQ. Furthermore, apoptosis induced in primary cultured cardiomyocytes by hypoxia/re-oxygenation was also inhibited by ODQ. These results suggest that the acceleration of cGMP production in cardiac mitochondria stimulates cytochrome c release from mitochondria in an MPT-independent manner, resulting in apoptosis.

scholarly journals Rhein ElicitsIn VitroCytotoxicity in Primary Human Liver HL-7702 Cells by Inducing Apoptosis through Mitochondria-Mediated Pathway

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Guy-Armel Bounda ◽  
Wang Zhou ◽  
Dan-dan Wang ◽  
Feng Yu
Keyword(s):  
Cytochrome C ◽  
Molecular Mechanisms ◽  
Caspase 3 ◽  
Morphological Changes ◽  
Fatty Degeneration ◽  
Apoptotic Cells ◽  
Dependent Manner ◽  
Caspase 9 ◽  
Cytochrome C Release ◽  
Induced Apoptosis

Objective. To study rhein-induced apoptosis signaling pathway and to investigate its molecular mechanisms in primary human hepatic cells.Results. Cell viability of HL-7702 cells treated with rhein showed significant decrease in dose-dependent manner. Following rhein treatment (25 μM, 50 μM, and 100 μM) for 12 h, the detection of apoptotic cells was significantly analyzed by flow cytometry and nuclear morphological changes by Hoechst 33258, respectively. Fatty degeneration studies showed upregulation level of the relevant hepatic markers (P< 0.01). Caspase activities expressed significant upregulation of caspase-3, caspase-9, and caspase-8. Moreover, apoptotic cells by rhein were significantly inhibited by Z-LEHD-FMK and Z-DEVD-FMK, caspase-9 inhibitor, and caspase-3 inhibitor, respectively. Overproduction of reactive oxygen species, lipid peroxidation, and loss of mitochondrial membrane potential were detected by fluorometry. Additionally, NAC, a ROS scavenger, significantly attenuated rhein-induced oxidative damage in HL-7702 cells. Furthermore, real-time qPCR results showed significant upregulation of p53, PUMA, Apaf-1, and Casp-9 and Casp-3 mRNA, with no significant changes of Fas and Cytochrome-c. Immunoblotting revealed significant Cytochrome-c release from mitochondria into cytosol and no change in Fas expression.Conclusion. Taken together, these observations suggested that rhein could induce apoptosis in HL-7702 cells via mitochondria-mediated signal pathway with involvement of oxidative stress mechanism.

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