1
|
Rouchidane Eyitayo A, Daury L, Priault M, Manon S. The membrane insertion of the pro-apoptotic protein Bax is a Tom22-dependent multi-step process: a study in nanodiscs. Cell Death Discov 2024; 10:335. [PMID: 39043635 PMCID: PMC11266675 DOI: 10.1038/s41420-024-02108-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 07/11/2024] [Accepted: 07/17/2024] [Indexed: 07/25/2024] Open
Abstract
Membrane insertion of the pro-apoptotic protein Bax was investigated by setting up cell-free synthesis of full-length Bax in the presence of pre-formed nanodiscs. While Bax was spontaneously poorly inserted in nanodiscs, co-synthesis with the mitochondrial receptor Tom22 stimulated Bax membrane insertion. The initial interaction of Bax with the lipid bilayer exposed the hydrophobic GALLL motif in Hα1 leading to Bax precipitation through hydrophobic interactions. The same motif was recognized by Tom22, triggering conformational changes leading to the extrusion and the ensuing membrane insertion of the C-terminal hydrophobic Hα9. Tom22 was also required for Bax-membrane insertion after Bax was activated either by BH3-activators or by its release from Bcl-xL by WEHI-539. The effect of Tom22 was impaired by D154Y substitution in Bax-Hα7 and T174P substitution in Bax-Hα9, which are found in several tumors. Conversely, a R9E substitution promoted a spontaneous insertion of Bax in nanodiscs, in the absence of Tom22. Both Tom22-activated Bax and BaxR9E alone permeabilized liposomes to dextran-10kDa and formed ~5-nm-diameter pores in nanodiscs. The concerted regulation of Bax membrane insertion by Tom22 and BH3-activators is discussed.
Collapse
Affiliation(s)
| | - Laetitia Daury
- CNRS, Université de Bordeaux, UMR 5248, CBMN, Pessac, France
| | - Muriel Priault
- CNRS, Université de Bordeaux, UMR 5095, IBGC, Bordeaux, France
| | - Stéphen Manon
- CNRS, Université de Bordeaux, UMR 5095, IBGC, Bordeaux, France.
| |
Collapse
|
2
|
Simonyan L, Gonin M, Hanks J, Friedlein J, Dutrec K, Arokium H, Rouchidane Eyitayo A, Doudy TM, Chaignepain S, Manon S, Dejean L. Non-phosphorylatable mutants of Ser184 lead to incomplete activation of Bax. Front Oncol 2023; 12:1068994. [PMID: 36741728 PMCID: PMC9892840 DOI: 10.3389/fonc.2022.1068994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/15/2022] [Indexed: 01/20/2023] Open
Abstract
The S184 residue of Bax is the target of several protein kinases regulating cell fate, including AKT. It is well-established that, in cellulo, the substitution of S184 by a non-phosphorylatable residue stimulates both the mitochondrial localization of Bax, cytochrome c release, and apoptosis. However, in in vitro experiments, substituted mutants did not exhibit any increase in their binding capacity to isolated mitochondria or liposomes. Despite exhibiting a significant increase of the 6A7 epitope exposure, substituted mutants remain limited in their ability to form large oligomers, suggesting that they high capacity to promote apoptosis in cells was more related to a high content than to an increased ability to form large pores in the outer mitochondrial membranes.
Collapse
Affiliation(s)
- Lilit Simonyan
- Université de Bordeaux, Centre National de la Recherche Scientifique (CNRS), Institut de Biochimie et de Génétique Cellulaires (IBGC), Bordeaux, France
| | - Mathilde Gonin
- Université de Bordeaux, Centre National de la Recherche Scientifique (CNRS), Institut de Biochimie et de Génétique Cellulaires (IBGC), Bordeaux, France
| | - James Hanks
- California State University of Fresno, Department of Chemistry and Biochemistry, Fresno, CA, United States
| | - Jordan Friedlein
- California State University of Fresno, Department of Chemistry and Biochemistry, Fresno, CA, United States
| | - Kevin Dutrec
- Université de Bordeaux, Centre National de la Recherche Scientifique (CNRS), Institut de Biochimie et de Génétique Cellulaires (IBGC), Bordeaux, France
| | - Hubert Arokium
- Université de Bordeaux, Centre National de la Recherche Scientifique (CNRS), Institut de Biochimie et de Génétique Cellulaires (IBGC), Bordeaux, France
| | - Akandé Rouchidane Eyitayo
- Université de Bordeaux, Centre National de la Recherche Scientifique (CNRS), Institut de Biochimie et de Génétique Cellulaires (IBGC), Bordeaux, France
| | - Toukounou Megann Doudy
- Université de Bordeaux, CNRS, Centre de Génomique Fonctionnelle Bordeaux (CGFB), Bordeaux, France
| | - Stéphane Chaignepain
- Université de Bordeaux, CNRS, Centre de Génomique Fonctionnelle Bordeaux (CGFB), Bordeaux, France
| | - Stéphen Manon
- Université de Bordeaux, Centre National de la Recherche Scientifique (CNRS), Institut de Biochimie et de Génétique Cellulaires (IBGC), Bordeaux, France,*Correspondence: Stéphen Manon, ; Laurent Dejean,
| | - Laurent Dejean
- California State University of Fresno, Department of Chemistry and Biochemistry, Fresno, CA, United States,*Correspondence: Stéphen Manon, ; Laurent Dejean,
| |
Collapse
|
3
|
Rouchidane Eyitayo A, Giraud MF, Daury L, Lambert O, Gonzalez C, Manon S. Cell-free synthesis and reconstitution of Bax in nanodiscs: Comparison between wild-type Bax and a constitutively active mutant. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184075. [PMID: 36273540 DOI: 10.1016/j.bbamem.2022.184075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/11/2022] [Accepted: 10/16/2022] [Indexed: 11/06/2022]
Abstract
Bax is a major player in the mitochondrial pathway of apoptosis, by making the Outer Mitochondrial Membrane (OMM) permeable to various apoptogenic factors, including cytochrome c. In order to get further insight into the structure and function of Bax when it is inserted in the OMM, we attempted to reconstitute Bax in nanodiscs. Cell-free protein synthesis in the presence of nanodiscs did not yield Bax-containing nanodiscs, but it provided a simple way to purify full-length Bax without any tag. Purified wild-type Bax (BaxWT) and a constitutively active mutant (BaxP168A) displayed biochemical properties that were in line with previous characterizations following their expression in yeast and human cells followed by their reconstitution into liposomes. Both Bax variants were then reconstituted in nanodiscs. Size exclusion chromatography, dynamic light scattering and transmission electron microscopy showed that nanodiscs formed with BaxP168A were larger than nanodiscs formed with BaxWT. This was consistent with the hypothesis that BaxP168A was reconstituted in nanodiscs as an active oligomer.
Collapse
Affiliation(s)
| | - Marie-France Giraud
- IBGC, UMR5095, CNRS, Université de Bordeaux, France; CBMN, UMR5248, CNRS, Université de Bordeaux, France
| | | | | | | | - Stéphen Manon
- IBGC, UMR5095, CNRS, Université de Bordeaux, France.
| |
Collapse
|
4
|
Bcl-2 Family Members and the Mitochondrial Import Machineries: The Roads to Death. Biomolecules 2022; 12:biom12020162. [PMID: 35204663 PMCID: PMC8961529 DOI: 10.3390/biom12020162] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 01/27/2023] Open
Abstract
The localization of Bcl-2 family members at the mitochondrial outer membrane (MOM) is a crucial step in the implementation of apoptosis. We review evidence showing the role of the components of the mitochondrial import machineries (translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM)) in the mitochondrial localization of Bcl-2 family members and how these machineries regulate the function of pro- and anti-apoptotic proteins in resting cells and in cells committed into apoptosis.
Collapse
|
5
|
Reconstituting the Mammalian Apoptotic Switch in Yeast. Genes (Basel) 2020; 11:genes11020145. [PMID: 32013249 PMCID: PMC7073680 DOI: 10.3390/genes11020145] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 01/28/2020] [Accepted: 01/28/2020] [Indexed: 12/22/2022] Open
Abstract
Proteins of the Bcl-2 family regulate the permeabilization of the mitochondrial outer membrane that represents a crucial irreversible step in the process of induction of apoptosis in mammalian cells. The family consists of both proapoptotic proteins that facilitate the membrane permeabilization and antiapoptotic proteins that prevent it in the absence of an apoptotic signal. The molecular mechanisms, by which these proteins interact with each other and with the mitochondrial membranes, however, remain under dispute. Although yeast do not have apparent homologues of these apoptotic regulators, yeast cells expressing mammalian members of the Bcl-2 family have proved to be a valuable model system, in which action of these proteins can be effectively studied. This review focuses on modeling the activity of proapoptotic as well as antiapoptotic proteins of the Bcl-2 family in yeast.
Collapse
|
6
|
Aghaei M, KhanAhmad H, Aghaei S, Ali Nilforoushzadeh M, Mohaghegh MA, Hejazi SH. The role of Bax in the apoptosis of Leishmania-infected macrophages. Microb Pathog 2019; 139:103892. [PMID: 31778755 DOI: 10.1016/j.micpath.2019.103892] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 10/30/2019] [Accepted: 11/23/2019] [Indexed: 12/18/2022]
Abstract
BACKGROUND Leishmania is a protozoan parasite that nests in macrophages and is responsible for the Leishmaniasis disease. In spite of different defense pathways, last strategy of macrophage for killing parasite is apoptosis process. By permeableizing the mitochondrial outer membrane (MOM). As breaching MOM releases apoptogenic factors like cytochrome-c which activate caspases that result in the destruction of the cell. In this review, we summarized the appropriate manuscripts regarding the bax includes, its different types and the effect of bax on the apoptosis of Leishmania and parasite-infected macrophages. METHODS Information about the role of BAX in the apoptosis of parasite-infected macrophage of recent articles were surveyed by searching computerized bibliographic database PubMed and Google Scholar entering the keywords BAX and leishmaniasis. RESULTS The common studies revealed Leishmania use different survival strategies for inhibiting macrophage apoptosis. As Leishmania by preventing homooligomerization or upregulating the anti-apoptotic molecule Bcl-2 can prohibits proteins of host-cell apoptosis such as Bax that is required for mitochondrial permeabilisation during apoptosis. CONCLUSION With regard to the supportive role of bax in apoptosis and the preventive role of Leishmania in its function, it seems that expression of bax gene in parasite by technologies like transgenic or down regulating of anti-apoptotic molecule Bcl-2 by miRNA could be prompted the apoptosis process of infected-macrophages and inhibited extensive spread of Leishmania and the resulting lesions.
Collapse
Affiliation(s)
- Maryam Aghaei
- Skin Diseases and Leishmaniasis Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hossein KhanAhmad
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shahrzad Aghaei
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | | | - Mohammad-Ali Mohaghegh
- Department of Laboratory Sciences, School of Paramedical Sciences, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh, Iran; Health Sciences Research Center, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh, Iran
| | - Seyed Hossein Hejazi
- Skin Diseases and Leishmaniasis Research Center, Isfahan University of Medical Sciences, Isfahan, Iran; Skin Disease and Leishmaniasis Research Center, Department of Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
| |
Collapse
|
7
|
Topology of active, membrane-embedded Bax in the context of a toroidal pore. Cell Death Differ 2018; 25:1717-1731. [PMID: 30185826 DOI: 10.1038/s41418-018-0184-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/20/2018] [Accepted: 05/21/2018] [Indexed: 01/18/2023] Open
Abstract
Bax is a Bcl-2 protein critical for apoptosis induction. In healthy cells, Bax is mostly a monomeric, cytosolic protein, while upon apoptosis initiation it inserts into the outer mitochondrial membrane, oligomerizes, and forms pores that release proapoptotic factors like Cytochrome c into the cytosol. The structures of active Bax and its homolog Bak are only partially understood and the topology of the proteins with respect to the membrane bilayer is controversially described in the literature. Here, we systematically review and examine the protein-membrane, protein-water, and protein-protein contacts of the nine helices of active Bax and Bak, and add a new set of topology data obtained by fluorescence and EPR methods. We conclude based on the consistent part of the datasets that the core/dimerization domain of Bax (Bak) is water exposed with only helices 4 and 5 in membrane contact, whereas the piercing/latch domain is in peripheral membrane contact, with helix 9 being transmembrane. Among the available structural models, those considering the dimerization/core domain at the rim of a toroidal pore are the most plausible to describe the active state of the proteins, although the structural flexibility of the piercing/latch domain does not allow unambiguous discrimination between the existing models.
Collapse
|
8
|
Popgeorgiev N, Jabbour L, Gillet G. Subcellular Localization and Dynamics of the Bcl-2 Family of Proteins. Front Cell Dev Biol 2018; 6:13. [PMID: 29497611 PMCID: PMC5819560 DOI: 10.3389/fcell.2018.00013] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/30/2018] [Indexed: 12/12/2022] Open
Abstract
Bcl-2 family proteins are recognized as major regulators of the mitochondrial pathway of apoptosis. They control the mitochondrial outer membrane permeabilization (MOMP) by directly localizing to this organelle. Further investigations demonstrated that Bcl-2 related proteins are also found in other intracellular compartments such as the endoplasmic reticulum, the Golgi apparatus, the nucleus and the peroxisomes. At the level of these organelles, Bcl-2 family proteins not only regulate MOMP in a remote fashion but also participate in major cellular processes including calcium homeostasis, cell cycle control and cell migration. With the advances of live cell imaging techniques and the generation of fluorescent recombinant proteins, it became clear that the distribution of Bcl-2 proteins inside the cell is a dynamic process which is profoundly affected by changes in the cellular microenvironment. Here, we describe the current knowledge related to the subcellular distribution of the Bcl-2 family of proteins and further emphasize on the emerging concept that this highly dynamic process is critical for cell fate determination.
Collapse
Affiliation(s)
- Nikolay Popgeorgiev
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, U1052 Institut National de la Santé et de la Recherche Médicale, UMR Centre National de la Recherche Scientifique 5286, Université Lyon I, Centre Léon Bérard, Lyon, France
| | - Lea Jabbour
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, U1052 Institut National de la Santé et de la Recherche Médicale, UMR Centre National de la Recherche Scientifique 5286, Université Lyon I, Centre Léon Bérard, Lyon, France
| | - Germain Gillet
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, U1052 Institut National de la Santé et de la Recherche Médicale, UMR Centre National de la Recherche Scientifique 5286, Université Lyon I, Centre Léon Bérard, Lyon, France.,Hospices Civils de Lyon, Laboratoire d'anatomie et Cytologie Pathologiques, Centre Hospitalier Lyon Sud, Pierre Bénite, France
| |
Collapse
|
9
|
Pang SW, Lahiri C, Poh CL, Tan KO. PNMA family: Protein interaction network and cell signalling pathways implicated in cancer and apoptosis. Cell Signal 2018; 45:54-62. [PMID: 29378289 DOI: 10.1016/j.cellsig.2018.01.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/23/2018] [Accepted: 01/23/2018] [Indexed: 12/22/2022]
Abstract
Paraneoplastic Ma Family (PNMA) comprises a growing number of family members which share relatively conserved protein sequences encoded by the human genome and is localized to several human chromosomes, including the X-chromosome. Based on sequence analysis, PNMA family members share sequence homology to the Gag protein of LTR retrotransposon, and several family members with aberrant protein expressions have been reported to be closely associated with the human Paraneoplastic Disorder (PND). In addition, gene mutations of specific members of PNMA family are known to be associated with human mental retardation or 3-M syndrome consisting of restrictive post-natal growth or dwarfism, and development of skeletal abnormalities. Other than sequence homology, the physiological function of many members in this family remains unclear. However, several members of this family have been characterized, including cell signalling events mediated by these proteins that are associated with apoptosis, and cancer in different cell types. Furthermore, while certain PNMA family members show restricted gene expression in the human brain and testis, other PNMA family members exhibit broader gene expression or preferential and selective protein interaction profiles, suggesting functional divergence within the family. Functional analysis of some members of this family have identified protein domains that are required for subcellular localization, protein-protein interactions, and cell signalling events which are the focus of this review paper.
Collapse
Affiliation(s)
- Siew Wai Pang
- Department of Biological Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia
| | - Chandrajit Lahiri
- Department of Biological Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia
| | - Chit Laa Poh
- Research Centre for Biomedical Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia
| | - Kuan Onn Tan
- Department of Biological Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia.
| |
Collapse
|
10
|
Mañas A, Chen W, Nelson A, Yao Q, Xiang J. BaxΔ2 sensitizes colorectal cancer cells to proteasome inhibitor-induced cell death. Biochem Biophys Res Commun 2018; 496:18-24. [PMID: 29291406 PMCID: PMC6022363 DOI: 10.1016/j.bbrc.2017.12.156] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 12/26/2017] [Indexed: 12/23/2022]
Abstract
Proteasome inhibitors, such as bortezomib and carfilzomib, are FDA approved for the treatment of hemopoietic cancers, but recent studies have shown their great potential for treatment of solid tumors. BaxΔ2, a unique proapoptotic Bax isoform, promotes non-mitochondrial cell death and sensitizes cancer cells to chemotherapy. However, endogenous BaxΔ2 proteins are unstable and susceptible to proteasomal degradation. Here, we screened a panel of proteasome inhibitors in colorectal cancer cells with different Bax statuses. We found that all proteasome inhibitors tested were able to block BaxΔ2 degradation without affecting the level of Baxα or Bcl-2 proteins. Among the inhibitors tested, only bortezomib and carfilzomib were able to induce differential cell death corresponding to the distinct Bax statuses. BaxΔ2-positive cells had a significantly higher level of cell death at low nanomolar concentrations than Baxα-positive or Bax-negative cells. Furthermore, bortezomib-induced cell death in BaxΔ2-positive cells was predominantly dependent on the caspase 8/3 pathway, consistent with our previous studies. These results imply that BaxΔ2 can selectively sensitize cancer cells to proteasome inhibitors, enhancing their potential to treat colon cancer and other solid tumors.
Collapse
Affiliation(s)
- Adriana Mañas
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Wenjing Chen
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Adam Nelson
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Qi Yao
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jialing Xiang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA.
| |
Collapse
|
11
|
N-terminal acetylation modulates Bax targeting to mitochondria. Int J Biochem Cell Biol 2017; 95:35-42. [PMID: 29233735 DOI: 10.1016/j.biocel.2017.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/28/2017] [Accepted: 12/06/2017] [Indexed: 01/13/2023]
Abstract
The pro-apoptotic Bax protein is the main effector of mitochondrial permeabilization during apoptosis. Bax is controlled at several levels, including post-translational modifications such as phosphorylation and S-palmitoylation. However, little is known about the contribution of other protein modifications to Bax activity. Here, we used heterologous expression of human Bax in yeast to study the involvement of N-terminal acetylation by yNaa20p (yNatB) on Bax function. We found that human Bax is N-terminal (Nt-)acetylated by yNaa20p and that Nt-acetylation of Bax is essential to maintain Bax in an inactive conformation in the cytosol of yeast and Mouse Embryonic Fibroblast (MEF) cells. Bax accumulates in the mitochondria of yeast naa20Δ and Naa25-/- MEF cells, but does not promote cytochrome c release, suggesting that an additional step is required for full activation of Bax. Altogether, our results show that Bax N-terminal acetylation by NatB is involved in its mitochondrial targeting.
Collapse
|
12
|
Mañas A, Wang S, Nelson A, Li J, Zhao Y, Zhang H, Davis A, Xie B, Maltsev N, Xiang J. The functional domains for Bax∆2 aggregate-mediated caspase 8-dependent cell death. Exp Cell Res 2017; 359:342-355. [PMID: 28807790 PMCID: PMC5718386 DOI: 10.1016/j.yexcr.2017.08.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/07/2017] [Accepted: 08/08/2017] [Indexed: 01/09/2023]
Abstract
Bax∆2 is a functional pro-apoptotic Bax isoform having alterations in its N-terminus, but sharing the rest of its sequence with Baxα. Bax∆2 is unable to target mitochondria due to the loss of helix α1. Instead, it forms cytosolic aggregates and activates caspase 8. However, the functional domain(s) responsible for BaxΔ2 behavior have remained elusive. Here we show that disruption of helix α1 makes Baxα mimic the behavior of Bax∆2. However, the other alterations in the Bax∆2 N-terminus have no significant impact on aggregation or cell death. We found that the hallmark BH3 domain is necessary but not sufficient for aggregation-mediated cell death. We also noted that the core region shared by Baxα and Bax∆2 is required for the formation of large aggregates, which is essential for BaxΔ2 cytotoxicity. However, aggregation by itself is unable to trigger cell death without the C-terminus. Interestingly, the C-terminal helical conformation, not its primary sequence, appears to be critical for caspase 8 recruitment and activation. As Bax∆2 shares core and C-terminal sequences with most Bax isoforms, our results not only reveal a structural basis for Bax∆2-induced cell death, but also imply an intrinsic potential for aggregate-mediated caspase 8-dependent cell death in other Bax family members.
Collapse
Affiliation(s)
- Adriana Mañas
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Sheng Wang
- Human Genetics Department, Computation Institute, University of Chicago, Chicago, IL 60637, USA
| | - Adam Nelson
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jiajun Li
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Yu Zhao
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Huaiyuan Zhang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Aislinn Davis
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Bingqing Xie
- Department of Computer Science, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Natalia Maltsev
- Human Genetics Department, Computation Institute, University of Chicago, Chicago, IL 60637, USA
| | - Jialing Xiang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA.
| |
Collapse
|
13
|
Simonyan L, Légiot A, Lascu I, Durand G, Giraud MF, Gonzalez C, Manon S. The substitution of Proline 168 favors Bax oligomerization and stimulates its interaction with LUVs and mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1144-1155. [DOI: 10.1016/j.bbamem.2017.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 02/28/2017] [Accepted: 03/14/2017] [Indexed: 12/23/2022]
|
14
|
Garenne D, Renault TT, Manon S. Bax mitochondrial relocation is linked to its phosphorylation and its interaction with Bcl-xL. MICROBIAL CELL 2016; 3:597-605. [PMID: 28357332 PMCID: PMC5348979 DOI: 10.15698/mic2016.12.547] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The heterologous expression of Bax, and other Bcl-2 family members, in the yeast Saccharomyces cerevisiae, has proved to be a valuable reporter system to investigate the molecular mechanisms underlying their interaction with mitochondria. By combining the co-expression of Bax and Bcl-xL mutants with analyzes of their localization and interaction in mitochondria and post-mitochondrial supernatants, we showed that the ability of Bax and Bcl-xL to interact is dependent both on Bax phosphorylation - mimicked by a substitution S184D - and by Bax and Bcl-xL localization. This, and previous data, provide the molecular basis for a model of dynamic equilibrium for Bax localization and activation, regulated both by phosphorylation and Bcl-xL.
Collapse
Affiliation(s)
- David Garenne
- Institut de Biochimie et de Génétique Cellulaires, UMR5095, CNRS & Université de Bordeaux, CS61390, 146 Rue Léo Saignat, 33077 Bordeaux, France. ; Present address: INRA, UMR1332, 71 Avenue Edouard Bourlaud, 33882 Villenave d'Ornon, France
| | - Thibaud T Renault
- Institut de Biochimie et de Génétique Cellulaires, UMR5095, CNRS & Université de Bordeaux, CS61390, 146 Rue Léo Saignat, 33077 Bordeaux, France. ; Present address: Department of Regulation in Infection Biology, Charitéplatz 1, 10117 Berlin, Germany
| | - Stéphen Manon
- Institut de Biochimie et de Génétique Cellulaires, UMR5095, CNRS & Université de Bordeaux, CS61390, 146 Rue Léo Saignat, 33077 Bordeaux, France
| |
Collapse
|
15
|
Wang H, He L, Pei Y, Chu P, Huang R, Li Y, Liao L, Zhu Z, Wang Y. Cloning and characterization of Bax1 and Bax2 genes of Ctenopharyngodon idellus and evaluation of transcript expression in response to grass carp reovirus infection. FISH PHYSIOLOGY AND BIOCHEMISTRY 2016; 42:1369-1382. [PMID: 27048597 DOI: 10.1007/s10695-016-0225-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/28/2016] [Indexed: 06/05/2023]
Abstract
Multidomain proapoptotic Bcl-2-associated X (Bax) protein is an essential effector responsible for mitochondrial outer membrane permeabilization, resulting in cell death via apoptosis. In this study, two Bax genes of grass carp (Ctenopharyngodon idellus), designated as CiBax1 and CiBax2, were isolated and analyzed. The obtained CiBax1 cDNA is 2058 bp long, with a 579 bp open reading frame (ORF) coding a protein of 192 amino acid residues. The full-length cDNA of CiBax2 is 1161 bp, with a 618 bp ORF coding 205 amino acids. Both CiBax1 and CiBax2 are typical members of Bcl-2 family containing conserved Bcl and C-terminal domains, and they share conserved synteny with zebrafish Bax genes despite the grass carp Bax mapping to different linkage groups. Phylogenetic analysis showed that CiBax1 was clustered with Bax from most teleost fish, and CiBax2 was close to Bax2 from teleost fish but far separated from that of Salmo salar. Quantitative real-time PCR analysis revealed broad expression of CiBax1 and CiBax2 in tissues from healthy grass carp, but the relative expression level differed. The mRNA expression of CiBax1 and CiBax2 was both upregulated significantly and peaked in all examined tissues at days 5 or 6 post-infection with grass carp reovirus. Subcellular localization indicated that CiBax1 protein was localized in both nucleus and cytosol, while CiBax2 protein only in cytosol. Moreover, CiBax2, but not CiBax1 was colocalized with mitochondrion under normal condition. Taken together, the findings would be helpful for further understanding of the function of Bax in teleost fish.
Collapse
Affiliation(s)
- Hao Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Libo He
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Yongyan Pei
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengfei Chu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Rong Huang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Yongming Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Lanjie Liao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Zuoyan Zhu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Yaping Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
| |
Collapse
|
16
|
Liu Z, Ding Y, Ye N, Wild C, Chen H, Zhou J. Direct Activation of Bax Protein for Cancer Therapy. Med Res Rev 2015; 36:313-41. [PMID: 26395559 DOI: 10.1002/med.21379] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 08/18/2015] [Accepted: 08/22/2015] [Indexed: 12/13/2022]
Abstract
Bax, a central cell death regulator, is an indispensable gateway to mitochondrial dysfunction and a major proapoptotic member of the B-cell lymphoma 2 (Bcl-2) family proteins that control apoptosis in normal and cancer cells. Dysfunction of apoptosis renders the cancer cell resistant to treatment as well as promotes tumorigenesis. Bax activation induces mitochondrial membrane permeabilization, thereby leading to the release of apoptotic factor cytochrome c and consequently cancer cell death. A number of drugs in clinical use are known to indirectly activate Bax. Intriguingly, recent efforts demonstrate that Bax can serve as a promising direct target for small-molecule drug discovery. Several direct Bax activators have been identified to hold promise for cancer therapy with the advantages of specificity and the potential of overcoming chemo- and radioresistance. Further investigation of this new class of drug candidates will be needed to advance them into the clinic as a novel means to treat cancer.
Collapse
Affiliation(s)
- Zhiqing Liu
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, 77555
| | - Ye Ding
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, 77555
| | - Na Ye
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, 77555
| | - Christopher Wild
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, 77555
| | - Haiying Chen
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, 77555
| | - Jia Zhou
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, 77555
| |
Collapse
|
17
|
Abstract
Permeabilization of the outer mitochondrial membrane that leads to the release of cytochrome c and several other apoptogenic proteins from mitochondria into cytosol represents a commitment point of apoptotic pathway in mammalian cells. This crucial event is governed by proteins of the Bcl-2 family. Molecular mechanisms, by which Bcl-2 family proteins permeabilize mitochondrial membrane, remain under dispute. Although yeast does not have apparent homologues of these proteins, when mammalian members of Bcl-2 family are expressed in yeast, they retain their activity, making yeast an attractive model system, in which to study their action. This review focuses on using yeast expressing mammalian proteins of the Bcl-2 family as a tool to investigate mechanisms, by which these proteins permeabilize mitochondrial membranes, mechanisms, by which pro- and antiapoptotic members of this family interact, and involvement of other cellular components in the regulation of programmed cell death by Bcl-2 family proteins.
Collapse
Affiliation(s)
- Peter Polčic
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic
| | - Petra Jaká
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic
| | - Marek Mentel
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic
| |
Collapse
|
18
|
Xu S, Liu J, Zhang Y, Wang C, Wang J, Yang Y, Huo J, Sun W. Apoptosis-related protein expression in rabbits with blast brain injury following early hyperbaric oxygen therapy. Neural Regen Res 2015; 7:1318-24. [PMID: 25657662 PMCID: PMC4308802 DOI: 10.3969/j.issn.1673-5374.2012.17.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 04/12/2012] [Indexed: 01/11/2023] Open
Abstract
We treated detonator-explosion-induced craniocerebral injury in rabbits with hyperbaric oxygen 1-24 hours post-injury. Expression of the apoptosis-regulating protein cytochrome c, the pro-apoptotic protein Bax and the apoptosis marker caspase-3 in the tissues surrounding the area of injury was significantly reduced, while that of the anti-apoptotic protein Bcl-2 was significantly increased. Our findings indicate that the curative effects of early hyperbaric oxygen on cortical cell apoptosis is associated with suppression of cytochrome c release from mitochondria. This mechanism underlies the observed reduction in Bax expression and upregulation of Bcl-2 expression.
Collapse
Affiliation(s)
- Shaonian Xu
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| | - Jiachuan Liu
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| | - Yongming Zhang
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| | - Chunlin Wang
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| | - Jinbiao Wang
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| | - Yanyan Yang
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| | - Jian Huo
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| | - Wenjiang Sun
- Department of Neurosurgery, the 105 Hospital of Chinese PLA, Hefei 230031, Anhui Province, China
| |
Collapse
|
19
|
Grazia G, Vegetti C, Benigni F, Penna I, Perotti V, Tassi E, Bersani I, Nicolini G, Canevari S, Carlo-Stella C, Gianni AM, Mortarini R, Anichini A. Synergistic anti-tumor activity and inhibition of angiogenesis by cotargeting of oncogenic and death receptor pathways in human melanoma. Cell Death Dis 2014; 5:e1434. [PMID: 25275595 PMCID: PMC4649516 DOI: 10.1038/cddis.2014.410] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/11/2014] [Accepted: 08/18/2014] [Indexed: 12/11/2022]
Abstract
Improving treatment of advanced melanoma may require the development of effective strategies to overcome resistance to different anti-tumor agents and to counteract relevant pro-tumoral mechanisms in the microenvironment. Here we provide preclinical evidence that these goals can be achieved in most melanomas, by co-targeting of oncogenic and death receptor pathways, and independently of their BRAF, NRAS, p53 and PTEN status. In 49 melanoma cell lines, we found independent susceptibility profiles for response to the MEK1/2 inhibitor AZD6244, the PI3K/mTOR inhibitor BEZ235 and the death receptor ligand TRAIL, supporting the rationale for their association. Drug interaction analysis indicated that a strong synergistic anti-tumor activity could be achieved by the three agents and the AZD6244–TRAIL association on 20/21 melanomas, including cell lines resistant to the inhibitors or to TRAIL. Mechanistically, synergy was explained by enhanced induction of caspase-dependent apoptosis, mitochondrial depolarization and modulation of key regulators of extrinsic and intrinsic cell death pathways, including c-FLIP, BIM, BAX, clusterin, Mcl-1 and several IAP family members. Moreover, silencing experiments confirmed the central role of Apollon downmodulation in promoting the apoptotic response of melanoma cells to the combinatorial treatments. In SCID mice, the AZD6244–TRAIL association induced significant growth inhibition of a tumor resistant to TRAIL and poorly responsive to AZD6244, with no detectable adverse events on body weight and tissue histology. Reduction in tumor volume was associated not only with promotion of tumor apoptosis but also with suppression of the pro-angiogenic molecules HIF1α, VEGFα, IL-8 and TGFβ1 and with inhibition of tumor angiogenesis. These results suggest that synergistic co-targeting of oncogenic and death receptor pathways can not only overcome melanoma resistance to different anti-tumor agents in vitro but can also promote pro-apoptotic effects and inhibition of tumor angiogenesis in vivo.
Collapse
Affiliation(s)
- G Grazia
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - C Vegetti
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - F Benigni
- San Raffaele Scientific Institute, URI, Milan, Italy
| | - I Penna
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - V Perotti
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - E Tassi
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - I Bersani
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - G Nicolini
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - S Canevari
- Functional Genomics Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - C Carlo-Stella
- 1] Department of Oncology and Hematology, Humanitas Cancer Center, Humanitas Clinical and Research Center, Rozzano, Italy [2] Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - A M Gianni
- Medical Oncology Unit 2, Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - R Mortarini
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| | - A Anichini
- Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, and Medical Oncology, Università degli Studi di Milano, Milan, Italy
| |
Collapse
|
20
|
Functions of the C-terminal domains of apoptosis-related proteins of the Bcl-2 family. Chem Phys Lipids 2014; 183:77-90. [PMID: 24892727 DOI: 10.1016/j.chemphyslip.2014.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 02/06/2023]
Abstract
Bcl-2 family proteins are involved in cell homeostasis, where they regulate cell death. Some of these proteins are pro-apoptotic and others pro-survival. Moreover, many of them share a similar domain composition with several of the so-called BH domains, although some only have a BH3 domain. A C-terminal domain is present in all the multi-BH domain proteins and in some of the BH3-only ones. This C-terminal domain is hydrophobic or amphipathic, for which reason it was thought when they were discovered that they were membrane anchors. Although this is indeed one of their functions, it has since been observed that they may also serve as regulators of the function of some members of this family, such as Bax. They may also serve to recognize the target membrane of some of these proteins, which only after an apoptotic signal, are incorporated into a membrane. It has been shown that peptides that imitate the sequence of C-terminal domains can form pores and may serve as a model to design cytotoxic molecules.
Collapse
|
21
|
Zhang H, Lin Y, Mañas A, Zhao Y, Denning MF, Ma L, Xiang J. BaxΔ2 Promotes Apoptosis through Caspase-8 Activation in Microsatellite-Unstable Colon Cancer. Mol Cancer Res 2014; 12:1225-32. [DOI: 10.1158/1541-7786.mcr-14-0162] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
22
|
Renault TT, Floros KV, Chipuk JE. BAK/BAX activation and cytochrome c release assays using isolated mitochondria. Methods 2013; 61:146-55. [PMID: 23567751 DOI: 10.1016/j.ymeth.2013.03.030] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 03/26/2013] [Accepted: 03/27/2013] [Indexed: 12/31/2022] Open
Abstract
The mitochondrial pathway of apoptosis proceeds when the outer mitochondrial membrane (OMM) is compromised by the pro-apoptotic BCL-2 family members, BAK and BAX. Once activated, BAK and BAX form proteolipid pores in the OMM leading to mitochondrial outer membrane permeabilization (MOMP), and the release of inner membrane space proteins, such as cytochrome c, which promotes caspase activation. The use of isolated mitochondria has been instrumental to understanding the key interactions necessary to engage BAK and BAX activation, MOMP, and apoptosis. Furthermore, it is possible to biochemically define the relationships between BCL-2 family function and mitochondrial physiology using isolated systems. Our laboratory uses freshly isolated mitochondria from numerous sources to better understand BCL-2 family function and requirements for BAK and BAX activation. Here, we will discuss commonly used in vitro techniques to perform MOMP and cytochrome c release assays; and provide several key methodologies to implicate BAK and BAX activity in these processes.
Collapse
Affiliation(s)
- Thibaud T Renault
- Icahn School of Medicine at Mount Sinai, Department of Oncological Sciences, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA
| | | | | |
Collapse
|
23
|
McNally MA, Soane L, Roelofs BA, Hartman AL, Hardwick JM. The N-terminal helix of Bcl-xL targets mitochondria. Mitochondrion 2013; 13:119-24. [PMID: 23333404 DOI: 10.1016/j.mito.2013.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 12/16/2012] [Accepted: 01/07/2013] [Indexed: 11/26/2022]
Abstract
Anti- and pro-apoptotic Bcl-2 family members regulate the mitochondrial phase of apoptotic cell death. The mitochondrial targeting mechanisms of Bcl-2 family proteins are tightly regulated. Known outer mitochondrial membrane targeting sequences include the C-terminal tail and central helical hairpin. Bcl-xL also localizes to the inner mitochondrial membrane, but these targeting sequences are unknown. Here we investigate the possibility that the N-terminus of Bcl-xL also contains mitochondrial targeting information. Amino acid residues 1-28 of Bcl-xL fused to EGFP are sufficient to target mitochondria. Although positive charges and helical propensity are required for targeting, similar to import sequences the N-terminus is not sufficient for efficient mitochondrial import.
Collapse
Affiliation(s)
- Melanie A McNally
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD 21205, USA.
| | | | | | | | | |
Collapse
|
24
|
Haferkamp B, Zhang H, Lin Y, Yeap X, Bunce A, Sharpe J, Xiang J. BaxΔ2 is a novel bax isoform unique to microsatellite unstable tumors. J Biol Chem 2012; 287:34722-9. [PMID: 22910913 PMCID: PMC3464575 DOI: 10.1074/jbc.m112.374785] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The pro-death Bcl-2 family protein and tumor suppressor Bax is frequently mutated in tumors with microsatellite instability (MSI). The mutation often results in a "Bax negative" phenotype and therefore is generally thought to be beneficial to the development of the tumor. Here, we report the identification of a novel Bax isoform, BaxΔ2, which is unique to microsatellite unstable tumors. BaxΔ2 is generated by a unique combination of a microsatellite deletion in Bax exon 3 and alternative splicing of Bax exon 2. Consistently, BaxΔ2 is only detected in MSI cell lines and primary tumors. BaxΔ2 is a potent cell death inducer but does not directly target mitochondria. In addition, BaxΔ2 sensitizes certain MSI tumor cells to a subset of chemotherapeutic agents, such as adriamycin. Thus, our data provide evidence that mutation and alternative splicing of tumor suppressors such as Bax are not always beneficial to tumor development but can be detrimental instead.
Collapse
Affiliation(s)
- Bonnie Haferkamp
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Honghong Zhang
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Yuting Lin
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Xinyi Yeap
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Alex Bunce
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | | | - Jialing Xiang
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
- To whom correspondence should be addressed: Dept. of Biological and Chemical Sciences, Illinois Institute of Technology, 3101 South Dearborn St., Chicago, IL 60616. Tel.: 312-567-3491; Fax: 312-567-3494; E-mail:
| |
Collapse
|
25
|
Non-apoptotic functions of apoptosis-regulatory proteins. EMBO Rep 2012; 13:322-30. [PMID: 22402666 DOI: 10.1038/embor.2012.19] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Accepted: 01/23/2012] [Indexed: 01/24/2023] Open
Abstract
During the past two decades, apoptotic cell death has been the subject of an intense wave of investigation, leading to the discovery of multiple gene products that govern both its induction and execution. In parallel, it has progressively become evident that most, if not all, proteins that had initially been discovered for their essential role in apoptosis also mediate a wide range of non-apoptotic functions. On the one hand, apoptotic regulators and executioners are involved in non-lethal physiological processes as diverse as cell cycle progression, differentiation, metabolism, autophagy and inflammation. On the other hand, pro-apoptotic proteins can control other modalities of programmed cell death, in particular regulated necrosis. In this review, we summarize the unconventional roles of the apoptotic core machinery from a functional perspective and discuss their pathophysiological implications.
Collapse
|
26
|
Interaction of the full-length Bax protein with biomimetic mitochondrial liposomes: A small-angle neutron scattering and fluorescence study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:384-401. [DOI: 10.1016/j.bbamem.2011.10.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 09/15/2011] [Accepted: 10/07/2011] [Indexed: 12/13/2022]
|
27
|
Rovini A, Savry A, Braguer D, Carré M. Microtubule-targeted agents: When mitochondria become essential to chemotherapy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:679-88. [DOI: 10.1016/j.bbabio.2011.01.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 01/02/2011] [Accepted: 01/04/2011] [Indexed: 12/22/2022]
|
28
|
Abstract
The pro-apoptototic protein Bax (Bcl-2 Associated protein X) plays a central role in the mitochondria-dependent apoptotic pathway. In healthy mammalian cells, Bax is essentially cytosolic and inactive. Following a death signal, the protein is translocated to the outer mitochondrial membrane, where it promotes a permeabilization that favors the release of different apoptogenic factors, such as cytochrome c. The regulation of Bax translocation is associated to conformational changes that are under the control of different factors. The evidences showing the involvement of different Bax domains in its mitochondrial localization are presented. The interactions between Bax and its different partners are described in relation to their ability to promote (or prevent) Bax conformational changes leading to mitochondrial addressing and to the acquisition of the capacity to permeabilize the outer mitochondrial membrane.
Collapse
Affiliation(s)
- Thibaud T Renault
- CNRS, Institut de Biochimie et de Génétique Cellulaires, UMR5095, F-33000 Bordeaux, France
| | | |
Collapse
|
29
|
Westphal D, Dewson G, Czabotar PE, Kluck RM. Molecular biology of Bax and Bak activation and action. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1813:521-31. [PMID: 21195116 DOI: 10.1016/j.bbamcr.2010.12.019] [Citation(s) in RCA: 378] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 12/17/2010] [Accepted: 12/19/2010] [Indexed: 12/26/2022]
Abstract
Bax and Bak are two nuclear-encoded proteins present in higher eukaryotes that are able to pierce the mitochondrial outer membrane to mediate cell death by apoptosis. Thus, organelles recruited by nucleated cells to supply energy can be recruited by Bax and Bak to kill cells. The two proteins lie in wait in healthy cells where they adopt a globular α-helical structure, seemingly as monomers. Following a variety of stress signals, they convert into pore-forming proteins by changing conformation and assembling into oligomeric complexes in the mitochondrial outer membrane. Proteins from the mitochondrial intermembrane space then empty into the cytosol to activate proteases that dismantle the cell. The arrangement of Bax and Bak in membrane-bound complexes, and how the complexes porate the membrane, is far from being understood. However, recent data indicate that they first form symmetric BH3:groove dimers which can be linked via an interface between the α6-helices to form high order oligomers. Here, we review how Bax and Bak change conformation and oligomerize, as well as how oligomers might form a pore. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
Collapse
|
30
|
Bax activation by engagement with, then release from, the BH3 binding site of Bcl-xL. Mol Cell Biol 2010; 31:832-44. [PMID: 21173168 DOI: 10.1128/mcb.00161-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bcl-2 homologues (such as Bcl-x(L)) promote survival in part through sequestration of "activator" BH3-only proteins (such as Puma), preventing them from directly activating Bax. It is thus assumed that inhibition of interactions between activators and Bcl-x(L) is a prerequisite for small molecules to antagonize Bcl-x(L) and induce cell death. The biological properties, described here of a terphenyl-based alpha-helical peptidomimetic inhibitor of Bcl-x(L) attest that displacement of Bax from Bcl-x(L) is also critical. Terphenyl 14 triggers Bax-dependent but Puma-independent cell death, disrupting Bax/Bcl-x(L) interactions without affecting Puma/Bcl-x(L) interactions. In cell-free assays, binding of inactive Bax to Bcl-x(L), followed by its displacement from Bcl-x(L) by terphenyl 14, produces mitochondrially permeabilizing Bax molecules. Moreover, the peptidomimetic kills yeast cells that express Bax and Bcl-x(L), and it uses Bax-binding Bcl-x(L) to induce mammalian cell death. Likewise, ectopic expression of Bax in yeast and mammalian cells enhances sensitivity to another Bcl-x(L) inhibitor, ABT-737, when Bcl-x(L) is present. Thus, the interaction of Bcl-x(L) with Bax paradoxically primes Bax at the same time it keeps Bax activity in check, and displacement of Bax from Bcl-x(L) triggers an apoptotic signal by itself. This mechanism might contribute to the clinical efficiency of Bcl-x(L) inhibitors.
Collapse
|
31
|
Yan B, Kong M, Chen YH. Prevention of apoptosis by the interaction between FIH1 and Bax. Mol Cell Biochem 2010; 348:1-9. [PMID: 21069436 DOI: 10.1007/s11010-010-0631-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 10/18/2010] [Indexed: 01/21/2023]
Abstract
Bax induces mitochondrial-dependent cell apoptosis signals in mammalian cells. However, the mechanism of how Bax is kept inactive is not fully elucidated. Here, we identify FIH1 as a potential interactor of Bax through mass spectrometry analysis. Coimmunoprecipitation and GST pull-down experiments show that FIH1 can directly interact with Bax. Bax-mediated apoptosis is suppressed by FIH1 overexpression, but accelerated by FIH1 deficiency. FIH1 functions as a cytosol retention factor of Bax, blocking Bax translocation from cytosol to mitochondria in response to apoptotic stimuli. Overall, there results unveil a novel role of FIH1 in the regulation of Bax-mediated apoptosis.
Collapse
Affiliation(s)
- Biao Yan
- Department of Biochemistry and Molecular Biology, College of Life Science and Technology, Tongji University, Shanghai, China.
| | | | | |
Collapse
|
32
|
Guillemin Y, Lopez J, Gimenez D, Fuertes G, Valero JG, Blum L, Gonzalo P, Salgado J, Girard-Egrot A, Aouacheria A. Active fragments from pro- and antiapoptotic BCL-2 proteins have distinct membrane behavior reflecting their functional divergence. PLoS One 2010; 5:e9066. [PMID: 20140092 PMCID: PMC2816717 DOI: 10.1371/journal.pone.0009066] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Accepted: 01/17/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The BCL-2 family of proteins includes pro- and antiapoptotic members acting by controlling the permeabilization of mitochondria. Although the association of these proteins with the outer mitochondrial membrane is crucial for their function, little is known about the characteristics of this interaction. METHODOLOGY/PRINCIPAL FINDINGS Here, we followed a reductionist approach to clarify to what extent membrane-active regions of homologous BCL-2 family proteins contribute to their functional divergence. Using isolated mitochondria as well as model lipid Langmuir monolayers coupled with Brewster Angle Microscopy, we explored systematically and comparatively the membrane activity and membrane-peptide interactions of fragments derived from the central helical hairpin of BAX, BCL-xL and BID. The results show a connection between the differing abilities of the assayed peptide fragments to contact, insert, destabilize and porate membranes and the activity of their cognate proteins in programmed cell death. CONCLUSION/SIGNIFICANCE BCL-2 family-derived pore-forming helices thus represent structurally analogous, but functionally dissimilar membrane domains.
Collapse
Affiliation(s)
- Yannis Guillemin
- Institut de Biologie et Chimie des Protéines (IBCP), CNRS UMR5086, University of Lyon, Lyon, France
| | - Jonathan Lopez
- Institut de Biologie et Chimie des Protéines (IBCP), CNRS UMR5086, University of Lyon, Lyon, France
| | - Diana Gimenez
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Paterna, Valencia, España
| | - Gustavo Fuertes
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Paterna, Valencia, España
| | - Juan Garcia Valero
- Institut de Biologie et Chimie des Protéines (IBCP), CNRS UMR5086, University of Lyon, Lyon, France
| | - Loïc Blum
- Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS), CNRS UMR5246, University of Lyon, Villeurbanne, France
| | - Philippe Gonzalo
- Institut de Biologie et Chimie des Protéines (IBCP), CNRS UMR5086, University of Lyon, Lyon, France
| | - Jesùs Salgado
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Paterna, Valencia, España
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia, España
| | - Agnès Girard-Egrot
- Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS), CNRS UMR5246, University of Lyon, Villeurbanne, France
| | - Abdel Aouacheria
- Institut de Biologie et Chimie des Protéines (IBCP), CNRS UMR5086, University of Lyon, Lyon, France
- * E-mail:
| |
Collapse
|
33
|
Kim H, Tu HC, Ren D, Takeuchi O, Jeffers JR, Zambetti GP, Hsieh JJD, Cheng EHY. Stepwise activation of BAX and BAK by tBID, BIM, and PUMA initiates mitochondrial apoptosis. Mol Cell 2010; 36:487-99. [PMID: 19917256 DOI: 10.1016/j.molcel.2009.09.030] [Citation(s) in RCA: 463] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 06/30/2009] [Accepted: 08/21/2009] [Indexed: 11/25/2022]
Abstract
While activation of BAX/BAK by BH3-only molecules (BH3s) is essential for mitochondrial apoptosis, the underlying mechanisms remain unsettled. Here we demonstrate that BAX undergoes stepwise structural reorganization leading to mitochondrial targeting and homo-oligomerization. The alpha1 helix of BAX keeps the alpha9 helix engaged in the dimerization pocket, rendering BAX as a monomer in cytosol. The activator BH3s, tBID/BIM/PUMA, attack and expose the alpha1 helix of BAX, resulting in secondary disengagement of the alpha9 helix and thereby mitochondrial insertion. Activator BH3s remain associated with the N-terminally exposed BAX through the BH1 domain to drive homo-oligomerization. BAK, an integral mitochondrial membrane protein, has bypassed the first activation step, explaining why its killing kinetics are faster than those of BAX. Furthermore, death signals initiated at ER induce BIM and PUMA to activate mitochondrial apoptosis. Accordingly, deficiency of Bim/Puma impedes ER stress-induced BAX/BAK activation and apoptosis. Our study provides mechanistic insights regarding the spatiotemporal execution of BAX/BAK-governed cell death.
Collapse
Affiliation(s)
- Hyungjin Kim
- Molecular Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | | | | | | | | | | | | |
Collapse
|
34
|
George NM, Targy N, Evans JJD, Zhang L, Luo X. Bax contains two functional mitochondrial targeting sequences and translocates to mitochondria in a conformational change- and homo-oligomerization-driven process. J Biol Chem 2009; 285:1384-92. [PMID: 19880508 DOI: 10.1074/jbc.m109.049924] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The apoptosis gateway protein Bax normally exists in the cytosol as a globular shaped monomer composed of nine alpha-helices. During apoptosis, Bax translocates to the mitochondria, forms homo-oligomers, and subsequently induces mitochondrial damage. The mechanism of Bax mitochondrial translocation remains unclear. Among the nine alpha-helices of Bax, helices 4, 5, 6, and 9 are capable of targeting a heterologous protein to mitochondria. However, only helices 6 and 9 can independently direct the oligomerized Bax to the mitochondria. Although Bax mitochondrial translocation can still proceed with mutations in either helix 6 or helix 9, combined mutations completely abolished mitochondrial targeting in response to activating signals. Using a proline mutagenesis scanning analysis, we demonstrated that conformational changes were sufficient to cause Bax to move from the cytosol to the mitochondria. Moreover, we found that homo-oligomerization of Bax contributed to its mitochondrial translocation. These results suggest that Bax is targeted to the mitochondria through the exposure of one or both of the two functional mitochondrial targeting sequences in a conformational change-driven and homo-oligomerization-aided process.
Collapse
Affiliation(s)
- Nicholas M George
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198-7696, USA
| | | | | | | | | |
Collapse
|
35
|
The Bax carboxy-terminal hydrophobic helix does not determine organelle-specific targeting but is essential for maintaining Bax in an inactive state and for stable mitochondrial membrane insertion. Apoptosis 2009; 15:14-27. [DOI: 10.1007/s10495-009-0410-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
36
|
Abstract
Bid, a pro-apoptotic member of the Bcl-2 family, was initially discovered through binding to both pro-apoptotic Bax and anti-apoptotic Bcl-2. During apoptosis, Bid can be cleaved not only by caspase-8 during death receptor apoptotic signaling, but also by other caspases, granzyme B, calpains and cathepsins. Protease-cleaved Bid migrates to mitochondria where it induces permeabilization of the outer mitochondrial membrane that is dependent on the pro-apoptotic proteins Bax and/or Bak, and thus Bid acts as a sentinel for protease-mediated death signals. Although sequence analysis suggests that Bid belongs to the BH3-only subgroup of the Bcl-2 family, structural and phylogenetic analysis suggests that Bid may be more related to multi-BH region proteins such as pro-apoptotic Bax. Analysis of membrane binding by protease-cleaved Bid reveals mechanistic similarities with the membrane binding of Bax. For both proteins, membrane binding is characterized by relief of N-terminal inhibition of sequences promoting migration to membranes, insertion into the bilayer of the central hydrophobic hairpin helices and exposure of the BH3 region. These findings implicate Bid as a BH3-only protein that is both structurally and functionally related to multi-BH region Bcl-2 family proteins such as Bax.
Collapse
|
37
|
Ferecatu I, Le Floch N, Bergeaud M, Rodríguez-Enfedaque A, Rincheval V, Oliver L, Vallette FM, Mignotte B, Vayssière JL. Evidence for a mitochondrial localization of the retinoblastoma protein. BMC Cell Biol 2009; 10:50. [PMID: 19555499 PMCID: PMC2711044 DOI: 10.1186/1471-2121-10-50] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 06/25/2009] [Indexed: 11/10/2022] Open
Abstract
Background The retinoblastoma protein (Rb) plays a central role in the regulation of cell cycle, differentiation and apoptosis. In cancer cells, ablation of Rb function or its pathway is a consequence of genetic inactivation, viral oncoprotein binding or deregulated hyperphosphorylation. Some recent data suggest that Rb relocation could also account for the regulation of its tumor suppressor activity, as is the case for other tumor suppressor proteins, such as p53. Results In this reported study, we present evidence that a fraction of the total amount of Rb protein can localize to the mitochondria in proliferative cells taken from both rodent and human cells. This result is also supported by the use of Rb siRNAs, which substantially reduced the amount of mitochondrial Rb, and by acellular assays, in which [35S]-Methionine-labeled Rb proteins bind strongly to mitochondria isolated from rat liver. Moreover, endogenous Rb is found in an internal compartment of the mitochondria, within the inner-membrane. This is consistent with the protection of Rb from alkaline treatment, which destroys any interaction of proteins that are weakly bound to mitochondria. Conclusion Although a few data regarding an unspecific cytosolic localization of Rb protein have been reported for some tumor cells, our results are the first evidence of a mitochondrial localization of Rb. The mitochondrial localization of Rb is observed in parallel with its classic nuclear location and paves the way for the study of potential as-yet-unknown roles of Rb at this site.
Collapse
Affiliation(s)
- Ioana Ferecatu
- Laboratoire de génétique et biologie cellulaire - CNRS UMR 8159, Université de Versailles Saint-Quentin-en-Yvelines, Versailles, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Bleicken S, Zeth K. Conformational changes and protein stability of the pro-apoptotic protein Bax. J Bioenerg Biomembr 2009; 41:29-40. [PMID: 19255832 PMCID: PMC2778690 DOI: 10.1007/s10863-009-9202-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 01/24/2009] [Indexed: 11/03/2022]
Abstract
Pro-apoptotic Bax is a soluble and monomeric protein under normal physiological conditions. Upon its activation substantial structural rearrangements occur: The protein inserts into the mitochondrial outer membrane and forms higher molecular weight oligomers. Subsequently, the cells can undergo apoptosis. In our studies, we focused on the structural rearrangements of Bax during oligomerization and on the protein stability. Both protein conformations exhibit high stability against thermal denaturation, chemically induced unfolding and proteolytic processing. The oligomeric protein is stable up to 90 degrees C as well as in solutions of 8 M urea or 6 M guanidinium hydrochloride. Helix 9 appears accessible in the monomer but hidden in the oligomer assessed by proteolysis. Tryptophan fluorescence indicates that the environment of the C-terminal protein half becomes more apolar upon oligomerization, whereas the loop region between helices 1 and 2 gets solvent exposed.
Collapse
Affiliation(s)
- Stephanie Bleicken
- Department of Membrane Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | | |
Collapse
|
39
|
How does the Bax-α1 targeting sequence interact with mitochondrial membranes? The role of cardiolipin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:623-31. [DOI: 10.1016/j.bbamem.2008.12.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 11/19/2008] [Accepted: 12/18/2008] [Indexed: 01/21/2023]
|
40
|
Ausili A, Torrecillas A, Martínez-Senac MM, Corbalán-García S, Gómez-Fernández JC. The interaction of the Bax C-terminal domain with negatively charged lipids modifies the secondary structure and changes its way of insertion into membranes. J Struct Biol 2008; 164:146-52. [DOI: 10.1016/j.jsb.2008.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 07/04/2008] [Accepted: 07/07/2008] [Indexed: 10/21/2022]
|
41
|
Cartron PF, Bellot G, Oliver L, Grandier-Vazeille X, Manon S, Vallette FM. Bax inserts into the mitochondrial outer membrane by different mechanisms. FEBS Lett 2008; 582:3045-51. [DOI: 10.1016/j.febslet.2008.07.047] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 07/14/2008] [Accepted: 07/18/2008] [Indexed: 11/25/2022]
|
42
|
Pereira C, Silva R, Saraiva L, Johansson B, Sousa M, Côrte-Real M. Mitochondria-dependent apoptosis in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1286-302. [DOI: 10.1016/j.bbamcr.2008.03.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 03/05/2008] [Accepted: 03/13/2008] [Indexed: 12/18/2022]
|
43
|
The pleiotropic effects of heterologous Bax expression in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1449-65. [DOI: 10.1016/j.bbamcr.2007.12.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 12/14/2007] [Accepted: 12/30/2007] [Indexed: 12/27/2022]
|
44
|
Valentijn AJ, Upton JP, Bates N, Gilmore AP. Bax targeting to mitochondria occurs via both tail anchor-dependent and -independent mechanisms. Cell Death Differ 2008; 15:1243-54. [PMID: 18437166 DOI: 10.1038/cdd.2008.39] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Bax is a member of the Bcl-2 family that, together with Bak, is required for permeabilisation of the outer mitochondrial membrane (OMM). Bax differs from Bak in that it is predominantly cytosolic in healthy cells and only associates with the OMM after an apoptotic signal. How Bax is targeted to the OMM is still a matter of debate, with both a C-terminal tail anchor and an N-terminal pre-sequence being implicated. We now show definitively that Bax does not contain an N-terminal import sequence, but does have a C-terminal anchor. The isolated N terminus of Bax cannot target a heterologous protein to the OMM, whereas the C terminus can. Furthermore, if the C terminus is blocked, Bax fails to target to mitochondria upon receipt of an apoptotic stimulus. Zebra fish Bax, which shows a high degree of amino-acid homology with mammalian Bax within the C terminus, but not in the N terminus, can rescue the defective cell-death phenotype of Bax/Bak-deficient cells. Interestingly, we find that Bax mutants, which themselves cannot target mitochondria or induce apoptosis, are recruited to clusters of activated wild-type Bax on the OMM of apoptotic cells. This appears to be an amplification of Bax activation during cell death that is independent of the normal tail anchor-mediated targeting.
Collapse
Affiliation(s)
- A J Valentijn
- Wellcome Trust Centre for Cell Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
| | | | | | | |
Collapse
|
45
|
Cytomegalovirus proteins vMIA and m38.5 link mitochondrial morphogenesis to Bcl-2 family proteins. J Virol 2008; 82:6232-43. [PMID: 18417572 DOI: 10.1128/jvi.02710-07] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apoptosis is a host defense mechanism against viruses that can be subverted by viral gene products. Human cytomegalovirus encodes viral mitochondria-localized inhibitor of apoptosis (vMIA; also known as pUL37x1), which is targeted to mitochondria and functions as a potent cell death suppressor by binding to and inhibiting proapoptotic Bcl-2 family members Bax and Bak. vMIA expression also dramatically alters mitochondrial morphology, causing the fragmentation of these organelles. A potential ortholog of vMIA, m38.5, which was identified in murine cytomegalovirus, has been shown to localize to mitochondria and protect against chemically induced apoptosis by unknown mechanisms. Despite sharing negligible homology with vMIA and no region detectably corresponding to the vMIA Bax-binding domain, we find that m38.5, like vMIA, binds to Bax and recruits Bax to mitochondria. Interestingly, m38.5 and vMIA appear to block Bax downstream of translocation to mitochondria and after an initial stage of Bax conformational change. In contrast to vMIA, m38.5 neither binds to Bak nor causes mitochondrial fragmentation. Consistently with Bax-selective inactivation by m38.5, m38.5 fragments mitochondria in Bak knockout (KO) cells and protects Bak KO cells from apoptosis better than Bax KO cells. Thus, vMIA and m38.5 share some, but not all, features of apoptosis regulation through Bcl-2 family interaction and allow the dissection of Bax translocation into discrete steps.
Collapse
|
46
|
Lalier L, Cartron PF, Juin P, Nedelkina S, Manon S, Bechinger B, Vallette FM. Bax activation and mitochondrial insertion during apoptosis. Apoptosis 2008; 12:887-96. [PMID: 17453158 DOI: 10.1007/s10495-007-0749-1] [Citation(s) in RCA: 237] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The mitochondrial apoptotic pathway is a highly regulated biological mechanism which determines cell fate. It is defined as a cascade of events, going from an apoptotic stimulus to the MOM permeabilization, resulting in the activation of the so-called executive phase. This pathway is very often altered in cancer cells. The mitochondrial permeabilization is under the control of the Bcl-2 family of proteins (pBcls). These proteins share one to four homology domains (designed BH1-4) with Bcl-2, and are susceptible of homo- and/or hetero-dimerization. In spite of a poor amino-acid sequence homology, these proteins exhibit very similar tertiary structures. Strikingly, while some of these proteins are anti-apoptotic, the others are pro-apoptotic. Pro-apoptotic proteins are further divided in two sub-classes: multi-domains proteins, among which Bax and Bak, which exhibit BH1-3 domains, and BH3-only proteins (or BOPs). Schematically, BOPs and anti-apoptotic proteins antagonistically regulate the activation of the multi-domain proteins Bax and Bak and their oligomerization in the MOM, the latter process being responsible for the apoptotic mitochondrial permeabilization. Considering the critical role of Bax in cancer cells apoptosis, we focus in this review on the molecular events of Bax activation through its interaction with the other proteins from the Bcl-2 family. The mechanism by which Bax triggers the MOM permeabilization once activated will be discussed in some other reviews in this special issue.
Collapse
|
47
|
Arokium H, Ouerfelli H, Velours G, Camougrand N, Vallette FM, Manon S. Substitutions of Potentially Phosphorylatable Serine Residues of Bax Reveal How They May Regulate Its Interaction with Mitochondria. J Biol Chem 2007; 282:35104-12. [PMID: 17911107 DOI: 10.1074/jbc.m704891200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
During apoptosis, the pro-apoptotic protein Bax relocalizes from the cytosol to the mitochondrial outer membrane. This relocalization is associated to major conformational changes, namely at the N- and C-terminal ends of the protein. Substitution of residues located at critical positions within the protein potentially stimulates or inhibits this process. In the present study, we investigated the hypothesis that phosphorylation of serine residues might trigger these conformational changes, with a focus on Ser(163) and Ser(184), which have been shown to be phosphorylatable by protein kinases GSK3beta and Akt/PKB, respectively, and on Ser(60), which is located in a consensus target sequence for PKA. Substitutions of these serine residues by alanine or aspartate were done in wild type or previously characterized Bax mutants, and the capacity of the resulting proteins to interact with mitochondria and to release cytochrome c was assayed in yeast, which provides a tool to study the function of Bax, independently of the rest of the apoptotic network. We conclude that sequential phosphorylation of these serine residues might participate in the triggering of the different conformational changes associated with Bax activation during apoptosis.
Collapse
Affiliation(s)
- Hubert Arokium
- CNRS, UMR5095, Université de Bordeaux 2, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France
| | | | | | | | | | | |
Collapse
|
48
|
Wattenberg BW, Clark D, Brock S. An artificial mitochondrial tail signal/anchor sequence confirms a requirement for moderate hydrophobicity for targeting. Biosci Rep 2007; 27:385-401. [PMID: 17968654 DOI: 10.1007/s10540-007-9061-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Accepted: 09/06/2007] [Indexed: 10/22/2022] Open
Abstract
Tail-anchored proteins are a group of membrane proteins oriented with their amino terminus in the cytoplasm and their carboxy terminus embedded in intracellular membranes. This group includes the apoptosis-mediating proteins of the Bcl-2 family as well as the vesicle targeting proteins of the SNARE group, among others. A stretch of hydrophobic amino acids at the extreme carboxy terminus of these proteins serves both as a membrane anchor and as a targeting signal. Tail-anchored proteins are differentially targeted to either the endoplasmic reticulum or the mitochondrial outer membrane and the mechanism which accomplishes this selective targeting is poorly understood. Here we define important characteristics of the signal/anchor region which directs proteins to the mitochondrial outer membrane. We have created an artificial sequence consisting of a stretch of 16 leucines bounded by positively charged amino acids. Using this template we demonstrate that moderate hydrophobicity distinguishes the mitochondrial tail-anchor sequence from that of the endoplasmic reticulum tail-anchor sequence. A change as small as introduction of a single polar residue into a sequence that otherwise targets to the endoplasmic reticulum can substantially switch targeting to the mitochondrial outer membrane. Further we show that a mitochondrially targeted tail-anchor has a higher propensity for the formation of alpha-helical structure than a sequence directing tail-anchored proteins to the endoplasmic reticulum.
Collapse
Affiliation(s)
- Binks W Wattenberg
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA.
| | | | | |
Collapse
|
49
|
Kalbfleisch T, Cambon A, Wattenberg BW. A bioinformatics approach to identifying tail-anchored proteins in the human genome. Traffic 2007; 8:1687-1694. [PMID: 17892534 DOI: 10.1111/j.1600-0854.2007.00661.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Intracellular proteins with a carboxy-terminal transmembrane domain and the amino-terminus oriented toward the cytosol are known as 'tail-anchored' proteins. Tail-anchored proteins have been of considerable interest because several important classes of proteins, including the vesicle-targeting/fusion proteins known as SNAREs and the apoptosis-related proteins of the Bcl-2 family, among others, utilize this unique membrane-anchoring motif. Here, we use a bioinformatic technique to develop a comprehensive list of potentially tail-anchored proteins in the human genome. Our final list contains 411 entries derived from 325 unique genes. We also analyzed both known and predicted tail-anchored proteins with respect to the amino acid composition of the transmembrane segments. This analysis revealed a distinctive composition of the membrane anchor in SNARE proteins.
Collapse
Affiliation(s)
- Ted Kalbfleisch
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Alex Cambon
- Department of Bioinformatics and Biostatistics, School of Public Health and Information Sciences, University of Louisville, Louisville, KY 40202, USA
| | - Binks W Wattenberg
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| |
Collapse
|
50
|
Ott M, Norberg E, Walter KM, Schreiner P, Kemper C, Rapaport D, Zhivotovsky B, Orrenius S. The mitochondrial TOM complex is required for tBid/Bax-induced cytochrome c release. J Biol Chem 2007; 282:27633-9. [PMID: 17635912 DOI: 10.1074/jbc.m703155200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome c release from mitochondria is a key event in apoptosis signaling that is regulated by Bcl-2 family proteins. Cleavage of the BH3-only protein Bid by multiple proteases leads to the formation of truncated Bid (tBid), which, in turn, promotes the oligomerization/insertion of Bax into the mitochondrial outer membrane and the resultant release of proteins residing in the intermembrane space. Bax, a monomeric protein in the cytosol, is targeted by a yet unknown mechanism to the mitochondria. Several hypotheses have been put forward to explain this targeting specificity. Using mitochondria isolated from different mutants of the yeast Saccharomyces cerevisiae and recombinant proteins, we have now investigated components of the mitochondrial outer membrane that might be required for tBid/Bax-induced cytochrome c release. Here, we show that the protein translocase of the outer mitochondrial membrane is required for Bax insertion and cytochrome c release.
Collapse
Affiliation(s)
- Martin Ott
- Institute of Environmental Medicine, Division of Toxicology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | | | | | | | | | | | | | | |
Collapse
|