Bcl-2 Family of Proteins: Life-or-Death Switch in Mitochondria

2002 ◽  
Vol 22 (1) ◽  
pp. 47-58 ◽  
Author(s):  
Yoshihide Tsujimoto
Keyword(s):  
Cell Death ◽  
Mitochondrial Membrane ◽  
Apoptotic Cell ◽  
Regulatory Protein ◽  
Family Members ◽  
Anion Channel ◽  
Permeability Transition ◽  
Outer Mitochondrial Membrane ◽  
Voltage Dependent Anion Channel ◽  
Membrane Barrier

An increase in the permeability of outer mitochondrial membrane is central to apoptotic cell death, and results in the release of several apoptogenic factors such as cytochrome c into the cytoplasm to activate downstream destructive programs. The voltage-dependent anion channel (VDAC or mitochondrial porin) plays an essential role in disrupting the mitochondrial membrane barrier and is regulated directly by members of the Bcl-2 family proteins. Anti-apoptotic Bcl-2 family members interact with and close the VDAC, whereas some, but not all, proapoptotic members interact with VDAC to open protein-conducting pore through which apoptogenic factors pass. Although the VDAC is involved directly in breaking the mitochondrial membrane barrier and is a known component of the permeability transition pore complex, VDAC-dependent increase in outer membrane permeability can be independent of the permeability transition event such as mitochondrial swelling followed by rupture of the outer mitochondrial membrane. VDAC interacts not only with Bcl-2 family members but also with proteins such as gelsolin, an actin regulatory protein, and appears to be a convergence point for a variety of cell survival and cell death signals.

scholarly journals Expression of leucine-rich repeat kinase 2 (LRRK2) inhibits the processing of uMtCK to induce cell death in a cell culture model system

2011 ◽  
Vol 31 (5) ◽  
pp. 429-437 ◽  
Author(s):  
Jie Cui ◽  
Mei Yu ◽  
Jingwen Niu ◽  
Zhenyu Yue ◽  
Zhiheng Xu
Keyword(s):  
Cell Death ◽  
Mitochondrial Membrane ◽  
Neuronal Apoptosis ◽  
Adenine Nucleotide ◽  
Anion Channel ◽  
Permeability Transition ◽  
Underlying Mechanism ◽  
Mutant Form ◽  
Leucine Rich Repeat ◽  
Voltage Dependent Anion Channel

PD (Parkinson's disease) is the most common neurodegenerative movement disorder. Mutations in LRRK2 (leucine-rich repeat kinase 2) gene are linked to the most common inherited and sporadic PD. Overexpression of LRRK2 and its mutants could induce mitochondrial-dependent neuronal apoptosis. However, the underlying mechanism remains elusive. We have identified several novel LRRK2 interacting proteins and showed that LRRK2 can interact with three components of the PTPC (permeability transition pore complex) including ANT (adenine nucleotide translocator), VDAC (voltage-dependent anion channel) and uMtCK [ubiquitous MtCK (mitochondrial creatine kinase)]. Those components have been reported to be involved in the permeability of mitochondrial membrane. We provide evidence that LRRK2 is likely to interact with uMtCK directly and expression of LRRK2 and its mutant form can suppress the processing of the immature form of uMtCK. LRRK2 expression keeps the uMtCK preprotein on the outer mitochondrial membrane instead of entering the mitochondria. In addition, the expression of both wild-type and mutant forms of LRRK2 promotes the interaction between ANT and VDAC, which plays a role in permeabilization transition pore opening. Finally, LRRK2-induced cell death can be suppressed by uMtCK. Our findings imply that LRRK2 can interact directly with uMtCK to block its entry into mitochondria and its subsequent processing, resulting in inhibition of mitochondrial energy channelling. Meanwhile, the decrease of uMtCK in mitochondria results in elevated interaction between ANT and VDAC and leads to neuronal apoptosis. Thus, our study provides the rational for clinical trials using creatine to treat PD and supports the notion of exploiting LRRK2 as a drug target for PD.

scholarly journals Biochemical and Genetic Analysis of the Mitochondrial Response of Yeast to BAX and BCL-XL

2000 ◽  
Vol 20 (9) ◽  
pp. 3125-3136 ◽  
Author(s):  
Atan Gross ◽  
Kirsten Pilcher ◽  
Elizabeth Blachly-Dyson ◽  
Emy Basso ◽  
Jennifer Jockel ◽  
...  
Keyword(s):  
Cell Death ◽  
Mitochondrial Genome ◽  
Atp Synthase ◽  
Mitochondrial Permeability Transition ◽  
Family Members ◽  
Growth Arrest ◽  
Anion Channel ◽  
Cell Killing ◽  
Β Subunit ◽  
Voltage Dependent Anion Channel

ABSTRACT The BCL-2 family includes both proapoptotic (e.g., BAX and BAK) and antiapoptotic (e.g., BCL-2 and BCL-XL) molecules. The cell death-regulating activity of BCL-2 members appears to depend on their ability to modulate mitochondrial function, which may include regulation of the mitochondrial permeability transition pore (PTP). We examined the function of BAX and BCL-XL using genetic and biochemical approaches in budding yeast because studies with yeast suggest that BCL-2 family members act upon highly conserved mitochondrial components. In this study we found that in wild-type yeast, BAX induced hyperpolarization of mitochondria, production of reactive oxygen species, growth arrest, and cell death; however, cytochrome c was not released detectably despite the induction of mitochondrial dysfunction. Coexpression of BCL-XL prevented all BAX-mediated responses. We also assessed the function of BCL-XL and BAX in the same strain of Saccharomyces cerevisiae with deletions of selected mitochondrial proteins that have been implicated in the function of BCL-2 family members. BAX-induced growth arrest was independent of the tested mitochondrial components, including voltage-dependent anion channel (VDAC), the catalytic β subunit or the δ subunit of the F0F1-ATP synthase, mitochondrial cyclophilin, cytochrome c, and proteins encoded by the mitochondrial genome as revealed by [rho 0] cells. In contrast, actual cell killing was dependent upon select mitochondrial components including the β subunit of ATP synthase and mitochondrial genome-encoded proteins but not VDAC. The BCL-XL protection from either BAX-induced growth arrest or cell killing proved to be independent of mitochondrial components. Thus, BAX induces two cellular processes in yeast which can each be abrogated by BCL-XL: cell arrest, which does not require aspects of mitochondrial biochemistry, and cell killing, which does.

A role for mitochondrial aquaporins in cellular life-and-death decisions?

2006 ◽  
Vol 291 (2) ◽  
pp. C195-C202 ◽  
Author(s):  
Wing-Kee Lee ◽  
Frank Thévenod
Keyword(s):  
Cell Death ◽  
Mitochondrial Membrane ◽  
Water Movement ◽  
Apoptotic Cell ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mitochondrial Swelling ◽  
Inner Mitochondrial Membrane ◽  
Osmotic Swelling ◽  
Life And Death

Mitochondria dominate the process of life-and-death decisions of the cell. Continuous generation of ATP is essential for cell sustenance, but, on the other hand, mitochondria play a central role in the orchestra of events that lead to apoptotic cell death. Changes of mitochondrial volume contribute to the modulation of physiological mitochondrial function, and several ion permeability pathways located in the inner mitochondrial membrane have been implicated in the mediation of physiological swelling-contraction reactions, such as the K+ cycle. However, the channels and transporters involved in these processes have not yet been identified. Osmotic swelling is also one of the fundamental characteristics exhibited by mitochondria in pathological situations, which activates downstream cascades, culminating in apoptosis. The permeability transition pore has long been postulated to be the primary mediator for water movement in mitochondrial swelling during cell death, but its molecular identity remains obscure. Inevitably, accumulating evidence shows that mitochondrial swelling induced by apoptotic stimuli can also occur independently of permeability transition pore activation. Recently, a novel mechanism for osmotic swelling of mitochondria has been described. Aquaporin-8 and -9 channels have been identified in the inner mitochondrial membrane of various tissues, including the kidney, liver, and brain, where they may mediate water transport associated with physiological volume changes, contribute to the transport of metabolic substrates, and/or participate in osmotic swelling induced by apoptotic stimuli. Hence, the recent discovery that aquaporins are expressed in mitochondria opens up new areas of investigation in health and disease.

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 Redox-dependent gating of VDAC by mitoNEET

2019 ◽  
Vol 116 (40) ◽  
pp. 19924-19929 ◽  
Author(s):  
Colin H. Lipper ◽  
Jason T. Stofleth ◽  
Fang Bai ◽  
Yang-Sung Sohn ◽  
Susmita Roy ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
Anion Channel ◽  
Fatty Acid Transport ◽  
Dependent Manner ◽  
Outer Mitochondrial Membrane ◽  
Voltage Dependent Anion Channel ◽  
Ros Homeostasis ◽  
Parkinson’S Diseases ◽  
Voltage Dependent

MitoNEET is an outer mitochondrial membrane protein essential for sensing and regulation of iron and reactive oxygen species (ROS) homeostasis. It is a key player in multiple human maladies including diabetes, cancer, neurodegeneration, and Parkinson’s diseases. In healthy cells, mitoNEET receives its clusters from the mitochondrion and transfers them to acceptor proteins in a process that could be altered by drugs or during illness. Here, we report that mitoNEET regulates the outer-mitochondrial membrane (OMM) protein voltage-dependent anion channel 1 (VDAC1). VDAC1 is a crucial player in the cross talk between the mitochondria and the cytosol. VDAC proteins function to regulate metabolites, ions, ROS, and fatty acid transport, as well as function as a “governator” sentry for the transport of metabolites and ions between the cytosol and the mitochondria. We find that the redox-sensitive [2Fe-2S] cluster protein mitoNEET gates VDAC1 when mitoNEET is oxidized. Addition of the VDAC inhibitor 4,4′-diisothiocyanatostilbene-2,2′-disulfonate (DIDS) prevents both mitoNEET binding in vitro and mitoNEET-dependent mitochondrial iron accumulation in situ. We find that the DIDS inhibitor does not alter the redox state of MitoNEET. Taken together, our data indicate that mitoNEET regulates VDAC in a redox-dependent manner in cells, closing the pore and likely disrupting VDAC’s flow of metabolites.

scholarly journals Bax and Bak Coalesce into Novel Mitochondria-Associated Clusters during Apoptosis

2001 ◽  
Vol 153 (6) ◽  
pp. 1265-1276 ◽  
Author(s):  
Amotz Nechushtan ◽  
Carolyn L. Smith ◽  
Itschak Lamensdorf ◽  
Soo-Han Yoon ◽  
Richard J. Youle
Keyword(s):  
Cell Death ◽  
Mitochondrial Membrane ◽  
Cluster Formation ◽  
Family Members ◽  
Outer Mitochondrial Membrane ◽  
Mitochondrial Membranes ◽  
Mitochondrial Translocation ◽  
Novel Structure ◽  
Large Clusters ◽  
Confocal And Electron Microscopy

Bax is a member of the Bcl-2 family of proteins known to regulate mitochondria-dependent programmed cell death. Early in apoptosis, Bax translocates from the cytosol to the mitochondrial membrane. We have identified by confocal and electron microscopy a novel step in the Bax proapoptotic mechanism immediately subsequent to mitochondrial translocation. Bax leaves the mitochondrial membranes and coalesces into large clusters containing thousands of Bax molecules that remain adjacent to mitochondria. Bak, a close homologue of Bax, colocalizes in these apoptotic clusters in contrast to other family members, Bid and Bad, which circumscribe the outer mitochondrial membrane throughout cell death progression. We found the formation of Bax and Bak apoptotic clusters to be caspase independent and inhibited completely and specifically by Bcl-XL, correlating cluster formation with cytotoxic activity. Our results reveal the importance of a novel structure formed by certain Bcl-2 family members during the process of cell death.

scholarly journals In self-defence: hexokinase promotes voltage-dependent anion channel closure and prevents mitochondria-mediated apoptotic cell death

2004 ◽  
Vol 377 (2) ◽  
pp. 347-355 ◽  
Author(s):  
Heftsi AZOULAY-ZOHAR ◽  
Adrian ISRAELSON ◽  
Salah ABU-HAMAD ◽  
Varda SHOSHAN-BARMATZ
Keyword(s):  
Cell Death ◽  
Cell Survival ◽  
Molecular Mechanisms ◽  
Apoptotic Cell ◽  
Direct Interaction ◽  
Anion Channel ◽  
Mitochondrial Outer Membrane ◽  
Voltage Dependent Anion Channel ◽  
Metabolic Intermediate ◽  
Voltage Dependent

In tumour cells, elevated levels of mitochondria-bound isoforms of hexokinase (HK-I and HK-II) result in the evasion of apoptosis, thereby allowing the cells to continue proliferating. The molecular mechanisms by which bound HK promotes cell survival are not yet fully understood. Our studies relying on the purified mitochondrial outer membrane protein VDAC (voltage-dependent anion channel), isolated mitochondria or cells in culture suggested that the anti-apoptotic activity of HK-I occurs via modulation of the mitochondrial phase of apoptosis. In the present paper, a direct interaction of HK-I with bilayer-reconstituted purified VDAC, inducing channel closure, is demonstrated for the first time. Moreover, HK-I prevented the Ca2+-dependent opening of the mitochondrial PTP (permeability transition pore) and release of the pro-apoptotic protein cytochrome c. The effects of HK-I on VDAC activity and PTP opening were prevented by the HK reaction product glucose 6-phosphate, a metabolic intermediate in most biosynthetic pathways. Furthermore, glucose 6-phosphate re-opened both the VDAC and the PTP closed by HK-I. The HK-I-mediated effects on VDAC and PTP were not observed using either yeast HK or HK-I lacking the N-terminal hydrophobic peptide responsible for binding to mitochondria, or in the presence of an antibody specific for the N-terminus of HK-I. Finally, HK-I overexpression in leukaemia-derived U-937 or vascular smooth muscle cells protected against staurosporine-induced apoptosis, with a decrease of up to 70% in cell death. These results offer insight into the mechanisms by which bound HK promotes tumour cell survival, and suggests that its overexpression not only ensures supplies of energy and phosphometabolites, but also reflects an anti-apoptotic defence mechanism.

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