scholarly journals Essential Role of Voltage-Dependent Anion Channel in Various Forms of Apoptosis in Mammalian Cells

2001 ◽  
Vol 152 (2) ◽  
pp. 237-250 ◽  
Author(s):  
Shigeomi Shimizu ◽  
Yosuke Matsuoka ◽  
Yasuo Shinohara ◽  
Yoshihiro Yoneda ◽  
Yoshihide Tsujimoto
Keyword(s):  
Cytochrome C ◽  
Mammalian Cells ◽  
Essential Role ◽  
Biological Significance ◽  
Anion Channel ◽  
Voltage Dependent Anion Channel ◽  
Cytochrome C Release ◽  
Isolated Mitochondria ◽  
Voltage Dependent ◽  
Induced Apoptosis

Through direct interaction with the voltage-dependent anion channel (VDAC), proapoptotic members of the Bcl-2 family such as Bax and Bak induce apoptogenic cytochrome c release in isolated mitochondria, whereas BH3-only proteins such as Bid and Bik do not directly target the VDAC to induce cytochrome c release. To investigate the biological significance of the VDAC for apoptosis in mammalian cells, we produced two kinds of anti-VDAC antibodies that inhibited VDAC activity. In isolated mitochondria, these antibodies prevented Bax-induced cytochrome c release and loss of the mitochondrial membrane potential (Δψ), but not Bid-induced cytochrome c release. When microinjected into cells, these anti-VDAC antibodies, but not control antibodies, also prevented Bax-induced cytochrome c release and apoptosis, whereas the antibodies did not prevent Bid-induced apoptosis, indicating that the VDAC is essential for Bax-induced, but not Bid-induced, apoptogenic mitochondrial changes and apoptotic cell death. In addition, microinjection of these anti-VDAC antibodies significantly inhibited etoposide-, paclitaxel-, and staurosporine-induced apoptosis. Furthermore, we used these antibodies to show that Bax- and Bak-induced lysis of red blood cells was also mediated by the VDAC on plasma membrane. Taken together, our data provide evidence that the VDAC plays an essential role in apoptogenic cytochrome c release and apoptosis in mammalian cells.

scholarly journals Oligomeric states of the voltage-dependent anion channel and cytochrome c release from mitochondria

2005 ◽  
Vol 386 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Ran ZALK ◽  
Adrian ISRAELSON ◽  
Erez S. GARTY ◽  
Heftsi AZOULAY-ZOHAR ◽  
Varda SHOSHAN-BARMATZ
Keyword(s):  
Cytochrome C ◽  
Dynamic Equilibrium ◽  
Resonance Energy ◽  
Permeability Transition Pore ◽  
Anion Channel ◽  
Permeability Transition ◽  
Cross Linking ◽  
Voltage Dependent Anion Channel ◽  
Cytochrome C Release ◽  
Voltage Dependent

The VDAC (voltage-dependent anion channel) plays a central role in apoptosis, participating in the release of apoptogenic factors including cytochrome c. The mechanisms by which VDAC forms a protein-conducting channel for the passage of cytochrome c are not clear. The present study approaches this problem by addressing the oligomeric status of VDAC and its role in the induction of the permeability transition pore and cytochrome c release. Chemical cross-linking of isolated mitochondria or purified VDAC with five different reagents proved that VDAC exists as dimers, trimers or tetramers. Fluorescence resonance energy transfer between fluorescently labelled VDACs supports the concept of dynamic VDAC oligomerization. Mitochondrial cross-linking prevented both permeability transition pore opening and release of cytochrome c, yet had no effect on electron transport or Ca2+ uptake. Bilayer-reconstituted purified cross-linked VDAC showed decreased conductance and voltage-independent channel activity. In the dithiobis(succinimidyl propionate)-cross-linked VDAC, these channel properties could be reverted to those of the native VDAC by cleavage of the cross-linking. Cross-linking of VDAC reconstituted into liposomes inhibited the release of the proteoliposome-encapsulated cytochrome c. Moreover, encapsulated, but not soluble cytochrome c induced oligomerization of liposome-reconstituted VDAC. Thus the results indicate that VDAC exists in a dynamic equilibrium between dimers and tetramers and suggest that oligomeric VDAC may be involved in mitochondria-mediated apoptosis.

scholarly journals Motifs of VDAC2 required for mitochondrial Bak import and tBid-induced apoptosis

2015 ◽  
Vol 112 (41) ◽  
pp. E5590-E5599 ◽  
Author(s):  
Shamim Naghdi ◽  
Péter Várnai ◽  
György Hajnóczky
Keyword(s):  
Sequence Similarity ◽  
Anion Channel ◽  
Loss Of Function ◽  
Voltage Dependent Anion Channel ◽  
Fundamental Function ◽  
Cytoplasmic Surface ◽  
Voltage Dependent ◽  
Critical Residues ◽  
Induced Apoptosis ◽  
Relevant Domain

Voltage-dependent anion channel (VDAC) proteins are major components of the outer mitochondrial membrane. VDAC has three isoforms with >70% sequence similarity and redundant roles in metabolite and ion transport. However, only Vdac2−/− (V2−/−) mice are embryonic lethal, indicating a unique and fundamental function of VDAC2 (V2). Recently, a specific V2 requirement was demonstrated for mitochondrial Bak import and truncated Bid (tBid)-induced apoptosis. To determine the relevant domain(s) of V2 involved, VDAC1 (V1) and V2 chimeric constructs were created and used to rescue V2−/− fibroblasts. Surprisingly, the commonly cited V2-specific N-terminal extension and cysteines were found to be dispensable for Bak import and high tBid sensitivity. In gain-of-function studies, V2 (123–179) was the minimal sequence sufficient to render V1 competent to support Bak insertion. Furthermore, in loss-of-function experiments, T168 and D170 were identified as critical residues. These motifs are conserved in zebrafish V2 (zfV2) that also rescued V2-deficient fibroblasts. Because high-resolution structures of zfV2 and mammalian V1 have become available, we could superimpose these structures and recognized that the critical V2-specific residues help to create a distinctive open “pocket” on the cytoplasmic surface that could facilitate Bak recruitment.

scholarly journals Structure of the human voltage-dependent anion channel

2008 ◽  
Vol 105 (40) ◽  
pp. 15370-15375 ◽  
Author(s):  
Monika Bayrhuber ◽  
Thomas Meins ◽  
Michael Habeck ◽  
Stefan Becker ◽  
Karin Giller ◽  
...  
Keyword(s):  
Metabolic Flux ◽  
3D Structure ◽  
Anion Channel ◽  
Bioinformatic Analysis ◽  
Mitochondrial Outer Membrane ◽  
Voltage Dependent Anion Channel ◽  
X Ray Crystallography ◽  
Voltage Dependent ◽  
Α Helix ◽  
Induced Apoptosis

The voltage-dependent anion channel (VDAC), also known as mitochondrial porin, is the most abundant protein in the mitochondrial outer membrane (MOM). VDAC is the channel known to guide the metabolic flux across the MOM and plays a key role in mitochondrially induced apoptosis. Here, we present the 3D structure of human VDAC1, which was solved conjointly by NMR spectroscopy and x-ray crystallography. Human VDAC1 (hVDAC1) adopts a β-barrel architecture composed of 19 β-strands with an α-helix located horizontally midway within the pore. Bioinformatic analysis indicates that this channel architecture is common to all VDAC proteins and is adopted by the general import pore TOM40 of mammals, which is also located in the MOM.

scholarly journals MAVS Regulates Apoptotic Cell Death by Decreasing K48-Linked Ubiquitination of Voltage-Dependent Anion Channel 1

2013 ◽  
Vol 33 (16) ◽  
pp. 3137-3149 ◽  
Author(s):  
Kai Guan ◽  
Zirui Zheng ◽  
Ting Song ◽  
Xiang He ◽  
Changzhi Xu ◽  
...  
Keyword(s):  
Cell Death ◽  
Apoptotic Cell ◽  
Anion Channel ◽  
Apoptotic Cell Death ◽  
Type I ◽  
Voltage Dependent Anion Channel ◽  
Voltage Dependent ◽  
Consequent Reduction ◽  
Mitochondrial Antiviral Signaling ◽  
Induced Apoptosis

The mitochondrial antiviral signaling protein MAVS (IPS-1, VISA, or Cardif) plays an important role in the host defense against viral infection by inducing type I interferon. Recent reports have shown that MAVS is also critical for virus-induced apoptosis. However, the mechanism of MAVS-mediated apoptosis induction remains unclear. Here, we show that MAVS binds to voltage-dependent anion channel 1 (VDAC1) and induces apoptosis by caspase-3 activation, which is independent of its role in innate immunity. MAVS modulates VDAC1 protein stability by decreasing its degradative K48-linked ubiquitination. In addition, MAVS knockout mouse embryonic fibroblasts (MEFs) display reduced VDAC1 expression with a consequent reduction of the vesicular stomatitis virus (VSV)-induced apoptosis response. Notably, the upregulation of VDAC1 triggered by VSV infection is completely abolished in MAVS knockout MEFs. We thus identify VDAC1 as a target of MAVS and describe a novel mechanism of MAVS control of virus-induced apoptotic cell death.

scholarly journals Depletion of a Toxoplasma porin leads to defects in mitochondrial morphology and contacts with the ER

2021 ◽  
Author(s):  
Natalia Mallo ◽  
Jana Ovciarikova ◽  
Erica S. Martins-Duarte ◽  
Stephan C. Baehr ◽  
Marco Biddau ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Protein Import ◽  
Morphological Changes ◽  
Anion Channel ◽  
Multiple Roles ◽  
Mitochondrial Morphology ◽  
Voltage Dependent Anion Channel ◽  
Voltage Dependent ◽  
Molecule Transport ◽  
Small Molecule Transport

The Voltage Dependent Anion channel (VDAC) is a ubiquitous channel in the outer membrane of the mitochondrion with multiple roles in protein, metabolite and small molecule transport. In mammalian cells, VDAC, as part of a larger complex including the inositol triphosphate receptor, has been shown to have a role in mediating contacts between the mitochondria and endoplasmic reticulum (ER). We identify VDAC of the pathogenic apicomplexan Toxoplasma gondii and demonstrate its importance for parasite growth. We show that VDAC is involved in protein import and metabolite transfer to mitochondria. Further, depletion of VDAC resulted in significant morphological changes of the mitochondrion and ER, suggesting a role in mediating contacts between these organelles in T. gondii.

scholarly journals Polyamine depletion prevents camptothecin-induced apoptosis by inhibiting the release of cytochromec

2002 ◽  
Vol 282 (6) ◽  
pp. C1290-C1297 ◽  
Author(s):  
Qing Yuan ◽  
Ramesh M. Ray ◽  
Leonard R. Johnson
Keyword(s):  
Cytochrome C ◽  
Mammalian Cells ◽  
Caspase 3 ◽  
Intestinal Epithelial ◽  
Caspase 9 ◽  
Cytochrome C Release ◽  
Polyamine Synthesis ◽  
Antiapoptotic Proteins ◽  
Induced Apoptosis ◽  
Rate Limiting

C1297, 2002; 10.1152/ajpcell.00351.2001.We have shown previously that depletion of polyamines delays apoptosis induced by camptothecin in rat intestinal epithelial cells (IEC-6). Mitochondria play an important role in the regulation of apoptosis in mammalian cells because apoptotic signals induce mitochondria to release cytochrome c. The latter interacts with Apaf-1 to activate caspase-9, which in turn activates downstream caspase-3. Bcl-2 family proteins are involved in the regulation of cytochrome c release from mitochondria. In this study, we examined the effects of polyamine depletion on the activation of the caspase cascade, release of cytochrome cfrom mitochondria, and expression and translocation of Bcl-2 family proteins. We inhibited ornithine decarboxylase, the first rate-limiting enzyme in polyamine synthesis, with α-difluoromethylornithine (DFMO) to deplete cells of polyamines. Depletion of polyamines prevented camptothecin-induced release of cytochrome c from mitochondria and decreased the activity of caspase-9 and caspase-3. The mitochondrial membrane potential was not disrupted when cytochrome c was released. Depletion of polyamines decreased translocation of Bax to mitochondria during apoptosis. The expression of antiapoptotic proteins Bcl-xL and Bcl-2 was increased in DFMO-treated cells. Caspase-8 activity and cleavage of Bid were decreased in cells depleted of polyamines. These results suggest that polyamine depletion prevents IEC-6 cells from apoptosis by preventing the translocation of Bax to mitochondria, thus preventing the release of cytochrome c.

scholarly journals Bid-induced Conformational Change of Bax Is Responsible for Mitochondrial Cytochrome c Release during Apoptosis

1999 ◽  
Vol 144 (5) ◽  
pp. 891-901 ◽  
Author(s):  
Solange Desagher ◽  
Astrid Osen-Sand ◽  
Anthony Nichols ◽  
Robert Eskes ◽  
Sylvie Montessuit ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Conformational Change ◽  
Granule Cells ◽  
Cerebellar Granule Cells ◽  
Tumor Cell Lines ◽  
Cytochrome C Release ◽  
Isolated Mitochondria ◽  
Bh3 Domain ◽  
Direct Binding ◽  
Induced Apoptosis

Here we report that in staurosporine-induced apoptosis of HeLa cells, Bid, a BH3 domain containing protein, translocates from the cytosol to mitochondria. This event is associated with a change in conformation of Bax which leads to the unmasking of its NH2-terminal domain and is accompanied by the release of cytochrome c from mitochondria. A similar finding is reported for cerebellar granule cells undergoing apoptosis induced by serum and potassium deprivation. The Bax-conformational change is prevented by Bcl-2 and Bcl-xL but not by caspase inhibitors. Using isolated mitochondria and various BH3 mutants of Bid, we demonstrate that direct binding of Bid to Bax is a prerequisite for Bax structural change and cytochrome c release. Bcl-xL can inhibit the effect of Bid by interacting directly with Bax. Moreover, using mitochondria from Bax-deficient tumor cell lines, we show that Bid- induced release of cytochrome c is negligible when Bid is added alone, but dramatically increased when Bid and Bax are added together. Taken together, our results suggest that, during certain types of apoptosis, Bid translocates to mitochondria and binds to Bax, leading to a change in conformation of Bax and to cytochrome c release from mitochondria.

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