1
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Jenner A, Garcia-Saez AJ. The regulation of the apoptotic pore-An immunological tightrope walk. Adv Immunol 2024; 162:59-108. [PMID: 38866439 DOI: 10.1016/bs.ai.2024.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Apoptotic pore formation in mitochondria is the pivotal point for cell death during mitochondrial apoptosis. It is regulated by BCL-2 family proteins in response to various cellular stress triggers and mediates mitochondrial outer membrane permeabilization (MOMP). This allows the release of mitochondrial contents into the cytosol, which triggers rapid cell death and clearance through the activation of caspases. However, under conditions of low caspase activity, the mitochondrial contents released into the cytosol through apoptotic pores serve as inflammatory signals and activate various inflammatory responses. In this chapter, we discuss how the formation of the apoptotic pore is regulated by BCL-2 proteins as well as other cellular or mitochondrial proteins and membrane lipids. Moreover, we highlight the importance of sublethal MOMP in the regulation of mitochondrial-activated inflammation and discuss its physiological consequences in the context of pathogen infection and disease and how it can potentially be exploited therapeutically, for example to improve cancer treatment.
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Affiliation(s)
- Andreas Jenner
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Ana J Garcia-Saez
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
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2
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Czabotar PE, Garcia-Saez AJ. Mechanisms of BCL-2 family proteins in mitochondrial apoptosis. Nat Rev Mol Cell Biol 2023; 24:732-748. [PMID: 37438560 DOI: 10.1038/s41580-023-00629-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2023] [Indexed: 07/14/2023]
Abstract
The proteins of the BCL-2 family are key regulators of mitochondrial apoptosis, acting as either promoters or inhibitors of cell death. The functional interplay and balance between the opposing BCL-2 family members control permeabilization of the outer mitochondrial membrane, leading to the release of activators of the caspase cascade into the cytosol and ultimately resulting in cell death. Despite considerable research, our knowledge about the mechanisms of the BCL-2 family of proteins remains insufficient, which complicates cell fate predictions and does not allow us to fully exploit these proteins as targets for drug discovery. Detailed understanding of the formation and molecular architecture of the apoptotic pore in the outer mitochondrial membrane remains a holy grail in the field, but new studies allow us to begin constructing a structural model of its arrangement. Recent literature has also revealed unexpected activities for several BCL-2 family members that challenge established concepts of how they regulate mitochondrial permeabilization. In this Review, we revisit the most important advances in the field and integrate them into a new structure-function-based classification of the BCL-2 family members that intends to provide a comprehensive model for BCL-2 action in apoptosis. We close this Review by discussing the potential of drugging the BCL-2 family in diseases characterized by aberrant apoptosis.
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Affiliation(s)
- Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia.
| | - Ana J Garcia-Saez
- Membrane Biophysics, Institute of Genetics, CECAD, University of Cologne, Cologne, Germany.
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3
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Moldoveanu T. Apoptotic mitochondrial poration by a growing list of pore-forming BCL-2 family proteins. Bioessays 2023; 45:e2200221. [PMID: 36650950 PMCID: PMC9975053 DOI: 10.1002/bies.202200221] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/31/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023]
Abstract
The pore-forming BCL-2 family proteins are effectors of mitochondrial poration in apoptosis initiation. Two atypical effectors-BOK and truncated BID (tBID)-join the canonical effectors BAK and BAX. Gene knockout revealed developmental phenotypes in the absence the effectors, supporting their roles in vivo. During apoptosis effectors are activated and change shape from dormant monomers to dynamic oligomers that associate with and permeabilize mitochondria. BID is activated by proteolysis, BOK accumulates on inhibition of its degradation by the E3 ligase gp78, while BAK and BAX undergo direct activation by BH3-only initiators, autoactivation, and crossactivation. Except tBID, effector oligomers on the mitochondria appear as arcs and rings in super-resolution microscopy images. The BH3-in-groove dimers of BAK and BAX, the tBID monomers, and uncharacterized BOK species are the putative building blocks of apoptotic pores. Effectors interact with lipids and bilayers but the mechanism of membrane poration remains elusive. I discuss effector-mediated mitochondrial poration.
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Affiliation(s)
- Tudor Moldoveanu
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences,Correspondence:
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4
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Ke FS, Holloway S, Uren RT, Wong AW, Little MH, Kluck RM, Voss AK, Strasser A. The BCL-2 family member BID plays a role during embryonic development in addition to its BH3-only protein function by acting in parallel to BAX, BAK and BOK. EMBO J 2022; 41:e110300. [PMID: 35758142 PMCID: PMC9340487 DOI: 10.15252/embj.2021110300] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 05/27/2022] [Accepted: 05/30/2022] [Indexed: 12/31/2022] Open
Abstract
The intrinsic apoptosis pathway, regulated by the BCL-2 protein family, is essential for embryonic development. Using mice lacking all known apoptosis effectors, BAX, BAK and BOK, we have previously defined the processes during development that require apoptosis. Rare Bok-/- Bax-/- Bak-/- triple knockout (TKO) mice developed to adulthood and several tissues that were thought to require apoptosis during development appeared normal. This raises the question if all apoptosis had been abolished in the TKO mice or if other BCL-2 family members could act as effectors of apoptosis. Here, we investigated the role of BID, generally considered to link the extrinsic and intrinsic apoptosis pathways, acting as a BH3-only protein initiating apoptosis upstream of BAX and BAK. We found that Bok-/- Bax-/- Bak-/- Bid-/- quadruple knockout (QKO) mice have additional developmental anomalies compared to TKO mice, consistent with a role of BID, not only upstream but also in parallel to BAX, BAK and BOK. Mitochondrial experiments identified a small cytochrome c-releasing activity of full-length BID. Collectively, these findings suggest a new effector role for BID in the intrinsic apoptosis pathway.
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Affiliation(s)
- Francine S Ke
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Steven Holloway
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia
| | - Rachel T Uren
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Agnes W Wong
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia
| | - Melissa H Little
- Department of PaediatricsUniversity of MelbourneMelbourneVicAustralia,Murdoch Children's Medical Research InstituteMelbourneVicAustralia
| | - Ruth M Kluck
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Anne K Voss
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Andreas Strasser
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
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5
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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: 19] [Impact Index Per Article: 9.5] [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.
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6
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Flores‐Romero H, Hohorst L, John M, Albert M, King LE, Beckmann L, Szabo T, Hertlein V, Luo X, Villunger A, Frenzel LP, Kashkar H, Garcia‐Saez AJ. BCL‐2‐family protein tBID can act as a BAX‐like effector of apoptosis. EMBO J 2021; 41:e108690. [PMID: 34931711 PMCID: PMC8762556 DOI: 10.15252/embj.2021108690] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 11/14/2021] [Accepted: 11/22/2021] [Indexed: 12/26/2022] Open
Abstract
During apoptosis, the BCL‐2‐family protein tBID promotes mitochondrial permeabilization by activating BAX and BAK and by blocking anti‐apoptotic BCL‐2 members. Here, we report that tBID can also mediate mitochondrial permeabilization by itself, resulting in release of cytochrome c and mitochondrial DNA, caspase activation and apoptosis even in absence of BAX and BAK. This previously unrecognized activity of tBID depends on helix 6, homologous to the pore‐forming regions of BAX and BAK, and can be blocked by pro‐survival BCL‐2 proteins. Importantly, tBID‐mediated mitochondrial permeabilization independent of BAX and BAK is physiologically relevant for SMAC release in the immune response against Shigella infection. Furthermore, it can be exploited to kill leukaemia cells with acquired venetoclax resistance due to lack of active BAX and BAK. Our findings define tBID as an effector of mitochondrial permeabilization in apoptosis and provide a new paradigm for BCL‐2 proteins, with implications for anti‐bacterial immunity and cancer therapy.
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Affiliation(s)
- Hector Flores‐Romero
- Institute for Genetics University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD) University of Cologne Cologne Germany
- Interfaculty Institute of Biochemistry Eberhard‐Karls‐Universität Tübingen Tübingen Germany
| | - Lisa Hohorst
- Institute for Genetics University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD) University of Cologne Cologne Germany
| | - Malina John
- Interfaculty Institute of Biochemistry Eberhard‐Karls‐Universität Tübingen Tübingen Germany
| | - Marie‐Christine Albert
- Institute for Molecular Immunology, and Center for Molecular Medicine Cologne (CMMC) Faculty of Medicine University Hospital of Cologne University of Cologne Cologne Germany
| | - Louise E King
- Institute for Genetics University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD) University of Cologne Cologne Germany
| | - Laura Beckmann
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD) University of Cologne Cologne Germany
- Department I of Internal Medicine University Hospital of Cologne Cologne Germany
- Center of Integrated Oncology ABCD University Hospital of Cologne Cologne Germany
| | - Tamas Szabo
- Division of Developmental Immunology Biocenter Medical University of Innsbruck Innsbruck Austria
| | - Vanessa Hertlein
- Interfaculty Institute of Biochemistry Eberhard‐Karls‐Universität Tübingen Tübingen Germany
| | - Xu Luo
- Eppley Institute for Research in Cancer and Allied Diseases Fred & Pamela Buffett Cancer Center University of Nebraska Medical Center Omaha ME USA
- Department of Pathology and Microbiology University of Nebraska Medical Center Omaha NE USA
| | - Andreas Villunger
- Division of Developmental Immunology Biocenter Medical University of Innsbruck Innsbruck Austria
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences Vienna Austria
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases Vienna Austria
| | - Lukas P Frenzel
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD) University of Cologne Cologne Germany
- Department I of Internal Medicine University Hospital of Cologne Cologne Germany
- Center of Integrated Oncology ABCD University Hospital of Cologne Cologne Germany
| | - Hamid Kashkar
- Institute for Molecular Immunology, and Center for Molecular Medicine Cologne (CMMC) Faculty of Medicine University Hospital of Cologne University of Cologne Cologne Germany
| | - Ana J Garcia‐Saez
- Institute for Genetics University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD) University of Cologne Cologne Germany
- Interfaculty Institute of Biochemistry Eberhard‐Karls‐Universität Tübingen Tübingen Germany
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7
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Contribution of Yeast Studies to the Understanding of BCL-2 Family Intracellular Trafficking. Int J Mol Sci 2021; 22:ijms22084086. [PMID: 33920941 PMCID: PMC8071328 DOI: 10.3390/ijms22084086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 12/24/2022] Open
Abstract
BCL-2 family members are major regulators of apoptotic cell death in mammals. They form an intricate regulatory network that ultimately regulates the release of apoptogenic factors from mitochondria to the cytosol. The ectopic expression of mammalian BCL-2 family members in the yeast Saccharomyces cerevisiae, which lacks BCL-2 homologs, has been long established as a useful addition to the available models to study their function and regulation. In yeast, individual proteins can be studied independently from the whole interaction network, thus providing insight into the molecular mechanisms underlying their function in a living context. Furthermore, one can take advantage of the powerful tools available in yeast to probe intracellular trafficking processes such as mitochondrial sorting and interactions/exchanges between mitochondria and other compartments, such as the endoplasmic reticulum that are largely conserved between yeast and mammals. Yeast molecular genetics thus allows the investigation of the role of these processes on the dynamic equilibrium of BCL-2 family members between mitochondria and extramitochondrial compartments. Here we propose a model of dynamic regulation of BCL-2 family member localization, based on available evidence from ectopic expression in yeast.
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8
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Gottlieb RA, Piplani H, Sin J, Sawaged S, Hamid SM, Taylor DJ, de Freitas Germano J. At the heart of mitochondrial quality control: many roads to the top. Cell Mol Life Sci 2021; 78:3791-3801. [PMID: 33544154 PMCID: PMC8106602 DOI: 10.1007/s00018-021-03772-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2021] [Indexed: 12/26/2022]
Abstract
Mitochondrial quality control depends upon selective elimination of damaged mitochondria, replacement by mitochondrial biogenesis, redistribution of mitochondrial components across the network by fusion, and segregation of damaged mitochondria by fission prior to mitophagy. In this review, we focus on mitochondrial dynamics (fusion/fission), mitophagy, and other mechanisms supporting mitochondrial quality control including maintenance of mtDNA and the mitochondrial unfolded protein response, particularly in the context of the heart.
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Affiliation(s)
- Roberta A Gottlieb
- Smidt Heart Institute, Cedars-Sinai Medical Center, AHSP9313, 127 S. San Vicente Blvd., Los Angeles, CA, 90048, USA.
| | - Honit Piplani
- Smidt Heart Institute, Cedars-Sinai Medical Center, AHSP9313, 127 S. San Vicente Blvd., Los Angeles, CA, 90048, USA
| | - Jon Sin
- Smidt Heart Institute, Cedars-Sinai Medical Center, AHSP9313, 127 S. San Vicente Blvd., Los Angeles, CA, 90048, USA
| | - Savannah Sawaged
- Smidt Heart Institute, Cedars-Sinai Medical Center, AHSP9313, 127 S. San Vicente Blvd., Los Angeles, CA, 90048, USA
| | - Syed M Hamid
- Smidt Heart Institute, Cedars-Sinai Medical Center, AHSP9313, 127 S. San Vicente Blvd., Los Angeles, CA, 90048, USA
| | - David J Taylor
- Smidt Heart Institute, Cedars-Sinai Medical Center, AHSP9313, 127 S. San Vicente Blvd., Los Angeles, CA, 90048, USA
| | - Juliana de Freitas Germano
- Smidt Heart Institute, Cedars-Sinai Medical Center, AHSP9313, 127 S. San Vicente Blvd., Los Angeles, CA, 90048, USA
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9
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The Mysteries around the BCL-2 Family Member BOK. Biomolecules 2020; 10:biom10121638. [PMID: 33291826 PMCID: PMC7762061 DOI: 10.3390/biom10121638] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 12/19/2022] Open
Abstract
BOK is an evolutionarily conserved BCL-2 family member that resembles the apoptotic effectors BAK and BAX in sequence and structure. Based on these similarities, BOK has traditionally been classified as a BAX-like pro-apoptotic protein. However, the mechanism of action and cellular functions of BOK remains controversial. While some studies propose that BOK could replace BAK and BAX to elicit apoptosis, others attribute to this protein an indirect way of apoptosis regulation. Adding to the debate, BOK has been associated with a plethora of non-apoptotic functions that makes this protein unpredictable when dictating cell fate. Here, we compile the current knowledge and open questions about this paradoxical protein with a special focus on its structural features as the key aspect to understand BOK biological functions.
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10
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Kitamata M, Hotta M, Hamada‐Nakahara S, Suetsugu S. The membrane binding and deformation property of vaccinia virus K1 ankyrin repeat domain protein. Genes Cells 2020; 25:187-196. [DOI: 10.1111/gtc.12749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/11/2020] [Accepted: 01/15/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Manabu Kitamata
- Graduate School of Science and Technology Nara Institute of Science and Technology Ikoma Japan
| | - Mitsukuni Hotta
- Graduate School of Science and Technology Nara Institute of Science and Technology Ikoma Japan
| | | | - Shiro Suetsugu
- Graduate School of Science and Technology Nara Institute of Science and Technology Ikoma Japan
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11
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Flores-Romero H, Ros U, García-Sáez AJ. A lipid perspective on regulated cell death. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2019; 351:197-236. [PMID: 32247580 DOI: 10.1016/bs.ircmb.2019.11.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lipids are fundamental to life as structural components of cellular membranes and for signaling. They are also key regulators of different cellular processes such as cell division, proliferation, and death. Regulated cell death (RCD) requires the engagement of lipids and lipid metabolism for the initiation and execution of its killing machinery. The permeabilization of lipid membranes is a hallmark of RCD that involves, for each kind of cell death, a unique lipid profile. While the permeabilization of the mitochondrial outer membrane allows the release of apoptotic factors to the cytosol during apoptosis, permeabilization of the plasma membrane facilitates the release of intracellular content in other nonapoptotic types of RCD like necroptosis and ferroptosis. Lipids and lipid membranes are important accessory molecules required for the activation of protein executors of cell death such as BAX in apoptosis and MLKL in necroptosis. Peroxidation of membrane phospholipids and the subsequent membrane destabilization is a prerequisite to ferroptosis. Here, we discuss how lipids are essential players in apoptosis, the most common form of RCD, and also their role in necroptosis and ferroptosis. Altogether, we aim to highlight the contribution of lipids and membrane dynamics in cell death regulation.
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Affiliation(s)
- Hector Flores-Romero
- Interfaculty Institute of Biochemistry, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
| | - Uris Ros
- Interfaculty Institute of Biochemistry, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, Eberhard-Karls-Universität Tübingen, Tübingen, Germany.
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12
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The Incomplete Puzzle of the BCL2 Proteins. Cells 2019; 8:cells8101176. [PMID: 31569576 PMCID: PMC6830314 DOI: 10.3390/cells8101176] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 09/25/2019] [Accepted: 09/26/2019] [Indexed: 02/07/2023] Open
Abstract
The proteins of the BCL2 family are key players in multiple cellular processes, chief amongst them being the regulation of mitochondrial integrity and apoptotic cell death. These proteins establish an intricate interaction network that expands both the cytosol and the surface of organelles to dictate the cell fate. The complexity and unpredictability of the BCL2 interactome resides in the large number of family members and of interaction surfaces, as well as on their different behaviours in solution and in the membrane. Although our current structural knowledge of the BCL2 proteins has been proven therapeutically relevant, the precise structure of membrane-bound complexes and the regulatory effect that membrane lipids exert over these proteins remain key questions in the field. Here, we discuss the complexity of BCL2 interactome, the new insights, and the black matter in the field.
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13
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López CA, Swift MF, Xu XP, Hanein D, Volkmann N, Gnanakaran S. Biophysical Characterization of a Nanodisc with and without BAX: An Integrative Study Using Molecular Dynamics Simulations and Cryo-EM. Structure 2019; 27:988-999.e4. [DOI: 10.1016/j.str.2019.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 12/21/2018] [Accepted: 03/15/2019] [Indexed: 10/27/2022]
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14
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Bax to the future - A novel, high-yielding approach for purification and expression of full-length Bax protein for structural studies. Protein Expr Purif 2019; 158:20-26. [PMID: 30738180 DOI: 10.1016/j.pep.2019.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 01/18/2019] [Accepted: 02/05/2019] [Indexed: 01/27/2023]
Abstract
Mitochondria-mediated apoptosis (programmed cell death) involves a sophisticated signaling and regulatory network that is regulated by the Bcl-2 protein family. Members of this family have either pro- or anti-apoptotic functions. An important pro-apoptotic member of this family is the cytosolic Bax. This protein is crucial for the onset of apoptosis by perforating the mitochondrial outer membrane (MOM). This process can be seen as point of no return, since disintegration of the MOM leads to the release of apotogenic factors such as cytochrome c into the cytosol triggering the activation of caspases and subsequent apoptotic steps. Bax is able to interact with the MOM with both its termini, making it inherently difficult to express in E. coli. In this study, we present a novel approach to express and purify full-length Bax with significantly increased yields, when compared to the commonly applied strategy. Using a double fusion approach with an N-terminal GST-tag and a C-terminal Intein-CBD-tag, we were able to render both Bax termini inactive and prevent disruptive interactions from occurring during gene expression. By deploying an Intein-CBD-tag at the C-terminus we were further able to avoid the introduction of any artificial residues, hence ensuring the native like activity of the membrane-penetrating C-terminus of Bax. Further, by engineering a His6-tag to the C-terminus of the CBD-tag we greatly improved the robustness of the purification procedure. We report yields for pure, full-length Bax protein that are increased by an order of magnitude, when compared to commonly used Bax expression protocols.
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15
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Direct Detection of Membrane-Inserting Fragments Defines the Translocation Pores of a Family of Pathogenic Toxins. J Mol Biol 2018; 430:3190-3199. [DOI: 10.1016/j.jmb.2018.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 06/26/2018] [Accepted: 07/03/2018] [Indexed: 11/22/2022]
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16
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Hung CL, Lin YY, Chang HH, Chiang YW. Accessing local structural disruption of Bid protein during thermal denaturation by absorption-mode ESR spectroscopy. RSC Adv 2018; 8:34656-34669. [PMID: 35548640 PMCID: PMC9087001 DOI: 10.1039/c8ra06740f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 10/04/2018] [Indexed: 01/19/2023] Open
Abstract
The apoptotic function of Bid does not depend on its native structure.
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Affiliation(s)
- Chien-Lun Hung
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Yu-Ying Lin
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Hsin-Ho Chang
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
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17
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Zhang J, Ming C, Zhang W, Okechukwu PN, Morak-Młodawska B, Pluta K, Jeleń M, Akim AM, Ang KP, Ooi KK. 10 H-3,6-Diazaphenothiazine induces G 2/M phase cell cycle arrest and caspase-dependent apoptosis and inhibits cell invasion of A2780 ovarian carcinoma cells through the regulation of NF-κB and (BIRC6-XIAP) complexes. DRUG DESIGN DEVELOPMENT AND THERAPY 2017; 11:3045-3063. [PMID: 29123378 PMCID: PMC5661483 DOI: 10.2147/dddt.s144415] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The asymptomatic properties and high treatment resistance of ovarian cancer result in poor treatment outcomes and high mortality rates. Although the fundamental chemotherapy provides promising anticancer activities, it is associated with severe side effects. The derivative of phenothiazine, namely, 10H-3,6-diazaphenothiazine (PTZ), was synthesized and reported with ideal anticancer effects in a previous paper. In this study, detailed anticancer properties of PTZ was examined on A2780 ovarian cancer cells by investigating the cytotoxicity profiles, mechanism of apoptosis, and cell invasion. Research outcomes revealed PTZ-induced dose-dependent inhibition on A2780 cancer cells (IC50 =0.62 µM), with significant less cytotoxicity toward HEK293 normal kidney cells and H9C2 normal heart cells. Generation of reactive oxygen species (ROS) and polarization of mitochondrial membrane potential (ΔΨm) suggests PTZ-induced cell death through oxidative damage. The RT2 Profiler PCR Array on apoptosis pathway demonstrated PTZ-induced apoptosis via intrinsic (mitochondria-dependent) and extrinsic (cell death receptor-dependent) pathway. Inhibition of NF-κB and subsequent inhibition of (BIRC6-XIAP) complex activities reduced the invasion rate of A2780 cancer cells penetrating through the Matrigel™ Invasion Chamber. Lastly, the cell cycle analysis hypothesizes that the compound is cytostatic and significantly arrests cell proliferation at G2/M phase. Hence, the exploration of the underlying anticancer mechanism of PTZ suggested its usage as promising chemotherapeutic agent.
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Affiliation(s)
- Jianxin Zhang
- Department of Gynecology and Obstetrics, Capital Medical University Affiliated Beijing Chaoyang Hospital, Beijing
| | - Chen Ming
- Department of Gynecologic Oncology, Taizhou People's Hospital, Jiangsu, People's Republic of China
| | | | | | - Beata Morak-Młodawska
- Department of Organic Chemistry, School of Pharmacy with the Division of Laboratory Medicine, The Medical University of Silesia, Sosnowiec, Poland
| | - Krystian Pluta
- Department of Organic Chemistry, School of Pharmacy with the Division of Laboratory Medicine, The Medical University of Silesia, Sosnowiec, Poland
| | - Małgorzata Jeleń
- Department of Organic Chemistry, School of Pharmacy with the Division of Laboratory Medicine, The Medical University of Silesia, Sosnowiec, Poland
| | - Abdah Md Akim
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang
| | | | - Kah Kooi Ooi
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang.,Research Centre for Crystaline Materials, School of Science and Technology, Sunway University, Petaling Jaya, Malaysia
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18
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Karageorgis A, Claron M, Jugé R, Aspord C, Thoreau F, Leloup C, Kucharczak J, Plumas J, Henry M, Hurbin A, Verdié P, Martinez J, Subra G, Dumy P, Boturyn D, Aouacheria A, Coll JL. Systemic Delivery of Tumor-Targeted Bax-Derived Membrane-Active Peptides for the Treatment of Melanoma Tumors in a Humanized SCID Mouse Model. Mol Ther 2017; 25:534-546. [PMID: 28153100 DOI: 10.1016/j.ymthe.2016.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/09/2016] [Accepted: 11/11/2016] [Indexed: 01/03/2023] Open
Abstract
Melanoma is a highly metastatic and deadly form of cancer. Invasive melanoma cells overexpress integrin αvβ3, which is a well-known target for Arg-Gly-Asp-based (RGD) peptides. We developed a sophisticated method to synthetize milligram amounts of a targeted vector that allows the RGD-mediated targeting, internalization, and release of a mitochondria-disruptive peptide derived from the pro-apoptotic Bax protein. We found that 2.5 μM Bax[109-127] was sufficient to destabilize the mitochondria in ten different tumor cell lines, even in the presence of the anti-apoptotic Bcl2 protein, which is often involved in tumor resistance. This pore-forming peptide displayed antitumor activity when it was covalently linked by a disulfide bridge to the tetrameric RAFT-c[RGD]4-platform and after intravenous injection in a human melanoma tumor model established in humanized immuno-competent mice. In addition to its direct toxic effect, treatment with this combination induced the release of the immuno-stimulating factor monocyte chimoattractant protein 1 (MCP1) in the blood and a decrease in the level of the pro-angiogenic factor FGF2. Our novel multifunctional, apoptosis-inducing agent could be further customized and assayed for potential use in tumor-targeted therapy.
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Affiliation(s)
- Anastassia Karageorgis
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France
| | - Michaël Claron
- Université Grenoble Alpes, 38000 Grenoble, France; CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France
| | - Romain Jugé
- Molecular Biology of the Cell Laboratory (LBMC), Ecole Normale Supérieure de Lyon, UMR 5239 CNRS - UCBL - ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | - Caroline Aspord
- Université Grenoble Alpes, 38000 Grenoble, France; EMR EFS-UGA-INSERM U1209- CNRS, Immunobiology and Immunotherapy of Chronic Diseases, 38706 La Tronche, France; EFS Rhone-Alpes, R&D Laboratory, 38701 La Tronche, France
| | - Fabien Thoreau
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France; CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France
| | - Claire Leloup
- Université Grenoble Alpes, 38000 Grenoble, France; EMR EFS-UGA-INSERM U1209- CNRS, Immunobiology and Immunotherapy of Chronic Diseases, 38706 La Tronche, France; EFS Rhone-Alpes, R&D Laboratory, 38701 La Tronche, France
| | - Jérôme Kucharczak
- Molecular Biology of the Cell Laboratory (LBMC), Ecole Normale Supérieure de Lyon, UMR 5239 CNRS - UCBL - ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | - Joël Plumas
- Université Grenoble Alpes, 38000 Grenoble, France; EMR EFS-UGA-INSERM U1209- CNRS, Immunobiology and Immunotherapy of Chronic Diseases, 38706 La Tronche, France; EFS Rhone-Alpes, R&D Laboratory, 38701 La Tronche, France
| | - Maxime Henry
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France
| | - Amandine Hurbin
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France
| | - Pascal Verdié
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Jean Martinez
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Gilles Subra
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Pascal Dumy
- CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France; CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Didier Boturyn
- Université Grenoble Alpes, 38000 Grenoble, France; CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France
| | - Abdel Aouacheria
- Molecular Biology of the Cell Laboratory (LBMC), Ecole Normale Supérieure de Lyon, UMR 5239 CNRS - UCBL - ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; Institut des Sciences de l'Evolution de Montpellier (ISEM), UMR 5554, Université de Montpellier, CNRS, IRD, EPHE, Place Eugène Bataillon, 34095 Montpellier, France.
| | - Jean-Luc Coll
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France.
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19
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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]
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20
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Gupta R, Ghosh S. JNK3 phosphorylates Bax protein and induces ability to form pore on bilayer lipid membrane. BIOCHIMIE OPEN 2017; 4:41-46. [PMID: 29450140 PMCID: PMC5801821 DOI: 10.1016/j.biopen.2017.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/01/2017] [Indexed: 11/15/2022]
Abstract
Bax is a pro-apoptotic cytosolic protein. In this work native (unphosphorylated) and JNK3 phosphorylated Bax proteins are studied on artificial bilayer membranes for pore formation. Phosphorylated Bax formed pore on the bilayer lipid membrane whereas native one does not. In cells undergoing apoptosis the pore formed by the phosphorylated Bax could be important in cytochrome c release from the mitochondrial intermembrane space to the cytosol. The low conductance (1.5 nS) of the open state of the phosphorylated Bax pore corresponds to pore diameter of 0.9 nm which is small to release cytochrome c (∼3.4 nm). We hypothesized that JNK3 phosphorylated Bax protein can form bigger pores after forming complexes with other mitochondrial proteins like VDAC, t-Bid etc. to release cytochrome c.
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Affiliation(s)
- Rajeev Gupta
- Department of Physiology, All India Institute of Medical Sciences, India
| | - Subhendu Ghosh
- Department of Biophysics, University of Delhi South Campus, India
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21
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Maes ME, Schlamp CL, Nickells RW. BAX to basics: How the BCL2 gene family controls the death of retinal ganglion cells. Prog Retin Eye Res 2017; 57:1-25. [PMID: 28064040 DOI: 10.1016/j.preteyeres.2017.01.002] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/22/2016] [Accepted: 01/03/2017] [Indexed: 12/19/2022]
Abstract
Retinal ganglion cell (RGC) death is the principal consequence of injury to the optic nerve. For several decades, we have understood that the RGC death process was executed by apoptosis, suggesting that there may be ways to therapeutically intervene in this cell death program and provide a more direct treatment to the cells and tissues affected in diseases like glaucoma. A major part of this endeavor has been to elucidate the molecular biological pathways active in RGCs from the point of axonal injury to the point of irreversible cell death. A major component of this process is the complex interaction of members of the BCL2 gene family. Three distinct family members of proteins orchestrate the most critical junction in the apoptotic program of RGCs, culminating in the activation of pro-apoptotic BAX. Once active, BAX causes irreparable damage to mitochondria, while precipitating downstream events that finish off a dying ganglion cell. This review is divided into two major parts. First, we summarize the extent of knowledge of how BCL2 gene family proteins interact to facilitate the activation and function of BAX. This area of investigation has rapidly changed over the last few years and has yielded a dramatically different mechanistic understanding of how the intrinsic apoptotic program is run in mammalian cells. Second, we provided a comprehensive analysis of nearly two decades of investigation of the role of BAX in the process of RGC death, much of which has provided many important insights into the overall pathophysiology of diseases like glaucoma.
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Affiliation(s)
- Margaret E Maes
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Cassandra L Schlamp
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Robert W Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA.
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22
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Pro-apoptotic cBid and Bax exhibit distinct membrane remodeling activities: An AFM study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:17-27. [PMID: 27755971 DOI: 10.1016/j.bbamem.2016.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 09/16/2016] [Accepted: 10/13/2016] [Indexed: 11/22/2022]
Abstract
Bcl-2 proteins are key regulators of the mitochondrial outer membrane (MOM) permeabilization that mediates apoptosis. During apoptosis, Bid is cleaved (cBid) and translocates to the MOM, where it activates Bax. Bax then oligomerizes and induces MOM permeabilization. However, little is known about how these proteins affect membrane organization aside from pore formation. In previous studies, we have shown that both cBid and Bax are able to remodel membranes and stabilize curvature. Here, we dissected the independent effects of Bax and cBid on supported lipid structures mimicking the mitochondrial composition by means of atomic force spectroscopy. We show that cBid did not permeabilize the membrane but lowered the membrane breakthrough force. On the other hand, Bax effects were dependent on its oligomeric state. Monomeric Bax did not affect the membrane properties. In contrast, oligomeric Bax lowered the breakthrough force of the membrane, which in the context of pore formation, implies a lowering of the line tension at the edge of the pore.
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23
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Caspase-3-dependent cleavage of Bcl-xL in the stroma exosomes is required for their uptake by hematological malignant cells. Blood 2016; 128:2655-2665. [PMID: 27742710 DOI: 10.1182/blood-2016-05-715961] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 10/05/2016] [Indexed: 12/31/2022] Open
Abstract
The intercellular crosstalk between hematological malignancies and the tumor microenvironment is mediated by cell-to-cell interactions and soluble factors. One component of the secretome that is gaining increasing attention is the extracellular vesicles and, in particular, the exosomes. Apart from the role as vectors of molecular information, exosomes have been shown to possess intrinsic biological activity. In this study, we found that caspase-3 is activated in L88 bone marrow stroma cell-derived exosomes and identified 1 of the substrates to be the antiapoptotic protein Bcl-xL. The cleaved Bcl-xL is found in a panel of normal and cancer cell-derived exosomes and is localized on the outer leaflet of the exosomal membrane. Incubation of the exosomes with a caspase-3 inhibitor or the pan-caspase inhibitor prevents the cleavage of Bcl-xL. Importantly, MCF-7 cell-derived exosomes that are caspase-3-deficient are enriched in full-length Bcl-xL, whereas ectopic expression of caspase-3 restores the cleavage of Bcl-xL. Chemical inhibition of Bcl-xL with ABT737 or molecular inhibition by using the D61A and D76A Bcl-xL mutant leads to a significant decrease in the uptake of exosomes by hematopoietic malignant cells. These data indicate that the cleaved Bcl-xL is required for the uptake of exosomes by myeloma and lymphoma cells, leading to their increased proliferation. In summary, we demonstrate for the first time that Bcl-xL is an exosomal caspase-3 substrate and that this processing is required for the uptake of exosomes by recipient cells.
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24
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Andreu-Fernández V, García-Murria MJ, Bañó-Polo M, Martin J, Monticelli L, Orzáez M, Mingarro I. The C-terminal Domains of Apoptotic BH3-only Proteins Mediate Their Insertion into Distinct Biological Membranes. J Biol Chem 2016; 291:25207-25216. [PMID: 27758854 DOI: 10.1074/jbc.m116.733634] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/31/2016] [Indexed: 11/06/2022] Open
Abstract
Changes in the equilibrium of pro- and anti-apoptotic members of the B-cell lymphoma-2 (Bcl-2) protein family in the mitochondrial outer membrane (MOM) induce structural changes that commit cells to apoptosis. Bcl-2 homology-3 (BH3)-only proteins participate in this process by either activating pro-apoptotic effectors or inhibiting anti-apoptotic components and by promoting MOM permeabilization. The association of BH3-only proteins with MOMs is necessary for the activation and amplification of death signals; however, the nature of this association remains controversial, as these proteins lack a canonical transmembrane sequence. Here we used an in vitro expression system to study the insertion capacity of hydrophobic C-terminal regions of the BH3-only proteins Bik, Bim, Noxa, Bmf, and Puma into microsomal membranes. An Escherichia coli complementation assay was used to validate the results in a cellular context, and peptide insertions were modeled using molecular dynamics simulations. We also found that some of the C-terminal domains were sufficient to direct green fluorescent protein fusion proteins to specific membranes in human cells, but the domains did not activate apoptosis. Thus, the hydrophobic regions in the C termini of BH3-only members associated in distinct ways with various biological membranes, suggesting that a detailed investigation of the entire process of apoptosis should include studying the membranes as a setting for protein-protein and protein-membrane interactions.
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Affiliation(s)
- Vicente Andreu-Fernández
- From the Departament de Bioquímica i Biologia Molecular, ERI BioTecMed, Universitat de València, E-46100 Burjassot, Spain.,the Laboratory of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain, and
| | - María J García-Murria
- From the Departament de Bioquímica i Biologia Molecular, ERI BioTecMed, Universitat de València, E-46100 Burjassot, Spain
| | - Manuel Bañó-Polo
- From the Departament de Bioquímica i Biologia Molecular, ERI BioTecMed, Universitat de València, E-46100 Burjassot, Spain
| | - Juliette Martin
- the Bases Moléculaires et Structurales des Systèmes Infectieux (BMSSI), CNRS UMR 5086, 7 Passage du Vercors, 69007 Lyon, France
| | - Luca Monticelli
- the Bases Moléculaires et Structurales des Systèmes Infectieux (BMSSI), CNRS UMR 5086, 7 Passage du Vercors, 69007 Lyon, France
| | - Mar Orzáez
- the Laboratory of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain, and
| | - Ismael Mingarro
- From the Departament de Bioquímica i Biologia Molecular, ERI BioTecMed, Universitat de València, E-46100 Burjassot, Spain,
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25
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Cholesterol Promotes Interaction of the Protein CLIC1 with Phospholipid Monolayers at the Air-Water Interface. MEMBRANES 2016; 6:membranes6010015. [PMID: 26875987 PMCID: PMC4812421 DOI: 10.3390/membranes6010015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 01/27/2016] [Accepted: 01/29/2016] [Indexed: 11/17/2022]
Abstract
CLIC1 is a Chloride Intracellular Ion Channel protein that exists either in a soluble state in the cytoplasm or as a membrane bound protein. Members of the CLIC family are largely soluble proteins that possess the intriguing property of spontaneous insertion into phospholipid bilayers to form integral membrane ion channels. The regulatory role of cholesterol in the ion-channel activity of CLIC1 in tethered lipid bilayers was previously assessed using impedance spectroscopy. Here we extend this investigation by evaluating the influence of cholesterol on the spontaneous membrane insertion of CLIC1 into Langmuir film monolayers prepared using 1-palmitoyl-2-oleoylphosphatidylcholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-ethanolamine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine alone or in combination with cholesterol. The spontaneous membrane insertion of CLIC1 was shown to be dependent on the presence of cholesterol in the membrane. Furthermore, pre-incubation of CLIC1 with cholesterol prior to its addition to the Langmuir film, showed no membrane insertion even in monolayers containing cholesterol, suggesting the formation of a CLIC1-cholesterol pre-complex. Our results therefore suggest that CLIC1 membrane interaction involves CLIC1 binding to cholesterol located in the membrane for its initial docking followed by insertion. Subsequent structural rearrangements of the protein would likely also be required along with oligomerisation to form functional ion channels.
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26
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Salvador-Gallego R, Mund M, Cosentino K, Schneider J, Unsay J, Schraermeyer U, Engelhardt J, Ries J, García-Sáez AJ. Bax assembly into rings and arcs in apoptotic mitochondria is linked to membrane pores. EMBO J 2016; 35:389-401. [PMID: 26783362 DOI: 10.15252/embj.201593384] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/01/2015] [Indexed: 11/09/2022] Open
Abstract
Bax is a key regulator of apoptosis that, under cell stress, accumulates at mitochondria, where it oligomerizes to mediate the permeabilization of the mitochondrial outer membrane leading to cytochrome c release and cell death. However, the underlying mechanism behind Bax function remains poorly understood. Here, we studied the spatial organization of Bax in apoptotic cells using dual-color single-molecule localization-based super-resolution microscopy. We show that active Bax clustered into a broad distribution of distinct architectures, including full rings, as well as linear and arc-shaped oligomeric assemblies that localized in discrete foci along mitochondria. Remarkably, both rings and arcs assemblies of Bax perforated the membrane, as revealed by atomic force microscopy in lipid bilayers. Our data identify the supramolecular organization of Bax during apoptosis and support a molecular mechanism in which Bax fully or partially delineates pores of different sizes to permeabilize the mitochondrial outer membrane.
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Affiliation(s)
- Raquel Salvador-Gallego
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Markus Mund
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | | | - Joseph Unsay
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Ulrich Schraermeyer
- Core Facility for Electron Microscopy Section for Experimental Vitreoretinal Surgery, Universitätsklinikum Tübingen, Tübingen, Germany
| | | | - Jonas Ries
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
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27
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Simonyan L, Renault TT, da Costa Novais MJ, Sousa MJ, Côrte-Real M, Camougrand N, Gonzalez C, Manon S. Regulation of Bax/mitochondria interaction by AKT. FEBS Lett 2015; 590:13-21. [DOI: 10.1002/1873-3468.12030] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 11/23/2015] [Accepted: 11/24/2015] [Indexed: 12/19/2022]
Affiliation(s)
| | | | | | | | | | | | | | - Stéphen Manon
- CNRS; Université de Bordeaux, UMR5095; Bordeaux France
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28
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Cosentino K, Ros U, García-Sáez AJ. Assembling the puzzle: Oligomerization of α-pore forming proteins in membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:457-466. [PMID: 26375417 DOI: 10.1016/j.bbamem.2015.09.013] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/26/2015] [Accepted: 09/09/2015] [Indexed: 12/21/2022]
Abstract
Pore forming proteins (PFPs) share the ability of creating pores that allow the passage of ions, proteins or other constituents through a wide variety of target membranes, ranging from bacteria to humans. They often cause cell death, as pore formation disrupts the membrane permeability barrier required for maintaining cell homeostasis. The organization into supramolecular complexes or oligomers that pierce the membrane is a common feature of PFPs. However, the molecular pathway of self-assembly and pore opening remains unclear. Here, we review the most recent discoveries in the mechanism of membrane oligomerization and pore formation of a subset of PFPs, the α-PFPs, whose pore-forming domains are formed by helical segments. Only now we are starting to grasp the molecular details of their function, mainly thanks to the introduction of single molecule microscopy and nanoscopy techniques. This article is part of a Special Issue entitled: Pore-forming toxins edited by Mauro Dalla Serra and Franco Gambale.
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.,Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Uris Ros
- Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.,Max-Planck Institute for Intelligent Systems, Stuttgart, Germany.,Center for Protein Studies, Havana University, Havana, Cuba
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.,Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
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29
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Bax monomers form dimer units in the membrane that further self-assemble into multiple oligomeric species. Nat Commun 2015; 6:8042. [PMID: 26271728 PMCID: PMC4557355 DOI: 10.1038/ncomms9042] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 07/11/2015] [Indexed: 12/12/2022] Open
Abstract
Bax is a key regulator of apoptosis that mediates the release of cytochrome c to the cytosol via oligomerization in the outer mitochondrial membrane before pore formation. However, the molecular mechanism of Bax assembly and regulation by other Bcl-2 members remains obscure. Here, by analysing the stoichiometry of Bax oligomers at the single-molecule level, we find that Bax binds to the membrane in a monomeric state and then self-assembles in <1 min. Strikingly, active Bax does not exist in a unique oligomeric state, but as several different species based on dimer units. Moreover, we show that cBid activates Bax without affecting its assembly, while Bcl-xL induces the dissociation of Bax oligomers. On the basis of our experimental data and theoretical modelling, we propose a new mechanism for the molecular pathway of Bax assembly to form the apoptotic pore.
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30
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Bleicken S, Jeschke G, Stegmueller C, Salvador-Gallego R, García-Sáez AJ, Bordignon E. Structural model of active Bax at the membrane. Mol Cell 2014; 56:496-505. [PMID: 25458844 DOI: 10.1016/j.molcel.2014.09.022] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 07/28/2014] [Accepted: 09/25/2014] [Indexed: 11/18/2022]
Abstract
Bax plays a central role in the mitochondrial pathway of apoptosis. Upon activation, cytosolic Bax monomers oligomerize on the surface of mitochondria and change conformation concertedly to punch holes into the outer membrane. The subsequent release of cytochrome c initiates cell death. However, the structure of membrane-inserted Bax and its mechanism of action remain largely unknown. Here, we propose a 3D model of active Bax at the membrane based on double electron-electron resonance (DEER) spectroscopy in liposomes and isolated mitochondria. We show that active Bax is organized at the membrane as assemblies of dimers. In addition to a stable dimerization domain, each monomer contains a more flexible piercing domain involved in interdimer interactions and pore formation. The most important structural change during Bax activation is the opening of the hairpin formed by helices 5 and 6, which adopts a clamp-like conformation central to the mechanism of mitochondrial permeabilization.
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Affiliation(s)
- Stephanie Bleicken
- Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany; German Cancer Research Center, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Strasse 4, 72076 Tübingen, Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Carolin Stegmueller
- Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany; German Cancer Research Center, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Strasse 4, 72076 Tübingen, Germany
| | - Raquel Salvador-Gallego
- Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany; German Cancer Research Center, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Strasse 4, 72076 Tübingen, Germany
| | - Ana J García-Sáez
- Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany; German Cancer Research Center, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Strasse 4, 72076 Tübingen, Germany.
| | - Enrica Bordignon
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland; Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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31
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Luo L, Yang J, Liu D. Integration and oligomerization of Bax protein in lipid bilayers characterized by single molecule fluorescence study. J Biol Chem 2014; 289:31708-31718. [PMID: 25288797 DOI: 10.1074/jbc.m114.583393] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Bax is a pro-apoptotic Bcl-2 family protein. The activated Bax translocates to mitochondria, where it forms pore and permeabilizes the mitochondrial outer membrane. This process requires the BH3-only activator protein (i.e. tBid) and can be inhibited by anti-apoptotic Bcl-2 family proteins such as Bcl-xL. Here by using single molecule fluorescence techniques, we studied the integration and oligomerization of Bax in lipid bilayers. Our study revealed that Bax can bind to lipid membrane spontaneously in the absence of tBid. The Bax pore formation undergoes at least two steps: pre-pore formation and membrane insertion. The activated Bax triggered by tBid or BH3 domain peptide integrates on bilayers and tends to form tetramers, which are termed as pre-pore. Subsequent insertion of the pre-pore into membrane is highly dependent on the composition of cardiolipin in lipid bilayers. Bcl-xL can translocate Bax from membrane to solution and inhibit the pore formation. The study of Bax integration and oligomerization at the single molecule level provides new evidences that may help elucidate the pore formation of Bax and its regulatory mechanism in apoptosis.
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Affiliation(s)
- Lu Luo
- Department of Pharmacology III and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu-Chong-Zhi Road, Shanghai 201203 and
| | - Jun Yang
- Shanghai Institute of Planned Parenthood Research, 2140 Xie Tu Road, Shanghai 200032, China
| | - Dongxiang Liu
- Department of Pharmacology III and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu-Chong-Zhi Road, Shanghai 201203 and.
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Andreu-Fernández V, Genoves A, Lee TH, Stellato M, Lucantoni F, Orzáez M, Mingarro I, Aguilar MI, Pérez-Payá E. Peptides derived from the transmembrane domain of Bcl-2 proteins as potential mitochondrial priming tools. ACS Chem Biol 2014; 9:1799-811. [PMID: 24905660 DOI: 10.1021/cb5002679] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Bcl-2 family of proteins is crucial for apoptosis regulation. Members of this family insert through a specific C-terminal anchoring transmembrane domain (TMD) in the mitochondrial outer membrane where they hierarchically interact to determine cell fate. While the mitochondrial membrane has been proposed to actively participate in these protein-protein interactions, the influence of the TMD in the membrane-mediated interaction is poorly understood. Synthetic peptides (TMD-pepts) corresponding to the putative TMD of antiapoptotic (Bcl-2, Bcl-xL, Bcl-w, and Mcl-1) and pro-apoptotic (Bax, Bak) members were synthesized and characterized. TMD-pepts bound more efficiently to mitochondria-like bilayers than to plasma membrane-like bilayers, and higher binding correlated with greater membrane perturbation. The Bcl-2 TMD peptides promoted mitochondrial outer membrane permeabilization (MOMP) and cytochrome c release from isolated mitochondria and different cell lines. TMD-pepts exhibited nonapoptotic pro-death activity when apoptosis stimuli were absent. In addition, the peptides enhanced the apoptotic pathway induced by chemotherapeutic agents in cotreatment. Overall, the membrane perturbation effects of the TMD-pepts observed in the present study open the way for their use as new chemical tools to sensitize tumor cells to chemotherapeutic agents, in accordance with the concept of mitochondria priming.
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Affiliation(s)
- Vicente Andreu-Fernández
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
| | - Ainhoa Genoves
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
- Instituto de Biomedicina de Valencia, IBV-CSIC, E-46010 Valencia, Spain
| | - Tzong-Hsien Lee
- Department
of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800 Australia
| | - Matthew Stellato
- Department
of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800 Australia
| | - Federico Lucantoni
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
| | - Mar Orzáez
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
| | - Ismael Mingarro
- Departament
de Bioquímica i Biologia Molecular, Universitat de València, 46100 Burjassot, Spain
| | - Marie-Isabel Aguilar
- Department
of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800 Australia
| | - Enrique Pérez-Payá
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
- Instituto de Biomedicina de Valencia, IBV-CSIC, E-46010 Valencia, Spain
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33
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Pataraia S, Liu Y, Lipowsky R, Dimova R. Effect of cytochrome c on the phase behavior of charged multicomponent lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2036-45. [DOI: 10.1016/j.bbamem.2014.04.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 04/14/2014] [Accepted: 04/18/2014] [Indexed: 11/25/2022]
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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.
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Abstract
Bax, despite being a cytosolic protein, has the distinct ability to form channels in the mitochondrial outer membrane, which are capable of releasing proteins that initiate the execution phase of apoptosis. When studied in a planar phospholipid membrane system, full-length activated Bax can form conducting entities consistent with linearly organized three-channel units displaying steep voltage-gating (n=14) that rivals that of channels in excitable membranes. In addition, the channels display strong positive co-operativity possibly arising from the charge distribution of the voltage sensors. On the basis of functional behaviour, one of the channels in this functional triplet is oriented in the opposite direction to the others often resulting in conflicts between the effects of the electric field and the positive co-operativity of adjacent channels. The closure of the first channel occurs at positive potentials and this permits the second to close, but at negative potentials. The closure of the second channel in turn permits closure of the third, but at positive potentials. Positive co-operativity manifests itself in a number of ways including the second and the third channels opening virtually simultaneously. This extraordinary behaviour must have important, although as yet undefined, physiological roles.
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36
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Abstract
Fluorescence imaging provides a powerful technique to visualize spatiotemporal dynamics of biomolecules in living cells, if fluorescent biosensors for the relevant biomolecules become available. Here I describe a fluorescent biosensor for a lipid second messenger, phosphatidylinositol 3,4,5-triphosphate (PI(3,4,5)P3). The biosensor overcomes limitations of existing methods for the lipid analysis and allows us to pinpoint that the PI(3,4,5)P3 concentrations are increasing and/or decreasing not only at the plasma membrane but also at organelle membranes, such as the Golgi apparatus membranes and endoplasmic reticulum membranes. The present biosensor has also been shown to be applicable to a variety of lipid second messengers, including diacylglycerol and phosphatidylinositol 3,4-bisphosphate.
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Affiliation(s)
- Moritoshi Sato
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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37
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Han E, Lee H. Effect of the structural difference between Bax-α5 and Bcl-xL-α5 on their interactions with lipid bilayers. Phys Chem Chem Phys 2014; 16:981-8. [DOI: 10.1039/c3cp53486c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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38
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Peter B, Polyansky AA, Fanucchi S, Dirr HW. A Lys-Trp cation-π interaction mediates the dimerization and function of the chloride intracellular channel protein 1 transmembrane domain. Biochemistry 2013; 53:57-67. [PMID: 24328417 DOI: 10.1021/bi401433f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Chloride intracellular channel protein 1 (CLIC1) is a dual-state protein that can exist either as a soluble monomer or in an integral membrane form. The oligomerization of the transmembrane domain (TMD) remains speculative despite it being implicated in pore formation. The extent to which electrostatic and van der Waals interactions drive folding and association of the dimorphic TMD is unknown and is complicated by the requirement of interactions favorable in both aqueous and membrane environments. Here we report a putative Lys37-Trp35 cation-π interaction and show that it stabilizes the dimeric form of the CLIC1 TMD in membranes. A synthetic 30-mer peptide comprising a K37M TMD mutant was examined in 2,2,2-trifluoroethanol, sodium dodecyl sulfate micelles, and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes using far-ultraviolet (UV) circular dichroism, fluorescence, and UV absorbance spectroscopy. Our data suggest that Lys37 is not implicated in the folding, stability, or membrane insertion of the TMD peptide. However, removal of this residue impairs the formation of dimers and higher-order oligomers. This is accompanied by a 30-fold loss of chloride influx activity, suggesting that dimerization modulates the rate of chloride conductance. We propose that, within membranes, individual TMD helices associate via a Lys37-mediated cation-π interaction to form active dimers. The latter findings are also supported by results of modeling a putative TMD dimer conformation in which Lys37 and Trp35 form cation-π pairs at the dimer interface. Dimeric helix bundles may then associate to form fully active ion channels. Thus, within a membrane-like environment, aromatic interactions involving a polar lysine side chain provide a thermodynamic driving force for helix-helix association.
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Affiliation(s)
- Bradley Peter
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand , Johannesburg 2050, South Africa
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39
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Vargas-Uribe M, Rodnin MV, Ladokhin AS. Comparison of membrane insertion pathways of the apoptotic regulator Bcl-xL and the diphtheria toxin translocation domain. Biochemistry 2013; 52:7901-9. [PMID: 24134052 DOI: 10.1021/bi400926k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The diphtheria toxin translocation domain (T-domain) and the apoptotic repressor Bcl-xL are membrane proteins that adopt their final topology by switching folds from a water-soluble to a membrane-inserted state. While the exact molecular mechanisms of this transition are not clearly understood in either case, the similarity in the structures of soluble states of the T-domain and Bcl-xL led to the suggestion that their membrane insertion pathways will be similar, as well. Previously, we have applied an array of spectroscopic methods to characterize the pH-triggered refolding and membrane insertion of the diphtheria toxin T-domain. Here, we use the same set of methods to describe the membrane insertion pathway of Bcl-xL, which allows us to make a direct comparison between both systems with respect to the thermodynamic stability in solution, pH-dependent membrane association, and transmembrane insertion. Thermal denaturation measured by circular dichroism indicates that, unlike the T-domain, Bcl-xL does not undergo a pH-dependent destabilization of the structure. Förster resonance energy transfer measurements demonstrate that Bcl-xL undergoes reversible membrane association modulated by the presence of anionic lipids, suggesting that formation of the membrane-competent form occurs close to the membrane interface. Membrane insertion of the main hydrophobic helical hairpin of Bcl-xL, α5-α6, was studied by site-selective attachment of environment-sensitive dye NBD. In contrast to the insertion of the corresponding TH8-TH9 hairpin into the T-domain, insertion of α5-α6 was found not to depend strongly on the presence of anionic lipids. Taken together, our results indicate that while Bcl-xL and the T-domain share structural similarities, their modes of conformational switching and membrane insertion pathways are distinctly different.
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Affiliation(s)
- Mauricio Vargas-Uribe
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center , Kansas City, Kansas 66160, United States
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40
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Maity A, Yadav S, Verma CS, Ghosh Dastidar S. Dynamics of Bcl-xL in water and membrane: molecular simulations. PLoS One 2013; 8:e76837. [PMID: 24116174 PMCID: PMC3792877 DOI: 10.1371/journal.pone.0076837] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 08/28/2013] [Indexed: 11/18/2022] Open
Abstract
The Bcl2 family of proteins is capable of switching the apoptotic machinery by directly controlling the release of apoptotic factors from the mitochondrial outer membrane. They have 'pro' and 'anti'-apoptotic subgroups of proteins which antagonize each other's function; however a detailed atomistic understanding of their mechanisms based on the dynamical events, particularly in the membrane, is lacking. Using molecular dynamics simulations totaling 1.6µs we outline the major differences between the conformational dynamics in water and in membrane. Using implicit models of solvent and membrane, the simulated results reveal a picture that is in agreement with the 'hit-and run' concept which states that BH3-only peptides displace the tail (which acts as a pseudo substrate of the protein itself) from its binding pocket; this helps the membrane association of the protein after which the BH3 peptide becomes free. From simulations, Bcl-xL appears to be auto-inhibited by its C-terminal tail that embeds into and covers the hydrophobic binding pocket. However the tail is unable to energetically compete with BH3-peptides in water. In contrast, in the membrane, neither the tail nor the BH3-peptides are stable in the binding pocket and appear to be easily dissociated off as the pocket expands in response to the hydrophobic environment. This renders the binding pocket large and open, thus receptive to interactions with other protein partners. Principal components of the motions are dramatically different in the aqueous and in the membrane environments and provide clues regarding the conformational transitions that Bcl-xL undergoes in the membrane, in agreement with the biochemical data.
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Affiliation(s)
- Atanu Maity
- Bioinformatics Centre, Bose Institute, Kolkata, West Bengal, India
| | - Seema Yadav
- Bioinformatics Centre, Bose Institute, Kolkata, West Bengal, India
| | - Chandra S. Verma
- Bioinformatics Institute, Agency for Science, Technology and Research, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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41
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Peter B, Ngubane NCML, Fanucchi S, Dirr HW. Membrane Mimetics Induce Helix Formation and Oligomerization of the Chloride Intracellular Channel Protein 1 Transmembrane Domain. Biochemistry 2013; 52:2739-49. [DOI: 10.1021/bi4002776] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Bradley Peter
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Nomxolisi Chloë Mina-Liz Ngubane
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Sylvia Fanucchi
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Heini W. Dirr
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
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42
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Caspase-8 binding to cardiolipin in giant unilamellar vesicles provides a functional docking platform for bid. PLoS One 2013; 8:e55250. [PMID: 23418437 PMCID: PMC3572128 DOI: 10.1371/journal.pone.0055250] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 12/21/2012] [Indexed: 12/28/2022] Open
Abstract
Caspase-8 is involved in death receptor-mediated apoptosis in type II cells, the proapoptotic programme of which is triggered by truncated Bid. Indeed, caspase-8 and Bid are the known intermediates of this signalling pathway. Cardiolipin has been shown to provide an anchor and an essential activating platform for caspase-8 at the mitochondrial membrane surface. Destabilisation of this platform alters receptor-mediated apoptosis in diseases such as Barth Syndrome, which is characterised by the presence of immature cardiolipin which does not allow caspase-8 binding. We used a simplified in vitro system that mimics contact sites and/or cardiolipin-enriched microdomains at the outer mitochondrial surface in which the platform consisting of caspase-8, Bid and cardiolipin was reconstituted in giant unilamellar vesicles. We analysed these vesicles by flow cytometry and confirm previous results that demonstrate the requirement for intact mature cardiolipin for caspase-8 activation and Bid binding and cleavage. We also used confocal microscopy to visualise the rupture of the vesicles and their revesiculation at smaller sizes due to alteration of the curvature following caspase-8 and Bid binding. Biophysical approaches, including Laurdan fluorescence and rupture/tension measurements, were used to determine the ability of these three components (cardiolipin, caspase-8 and Bid) to fulfil the minimal requirements for the formation and function of the platform at the mitochondrial membrane. Our results shed light on the active functional role of cardiolipin, bridging the gap between death receptors and mitochondria.
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43
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Garg P, Nemec KN, Khaled AR, Tatulian SA. Transmembrane pore formation by the carboxyl terminus of Bax protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:732-42. [DOI: 10.1016/j.bbamem.2012.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 07/29/2012] [Accepted: 08/07/2012] [Indexed: 12/29/2022]
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44
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Charge Pair Interactions in Transmembrane Helices and Turn Propensity of the Connecting Sequence Promote Helical Hairpin Insertion. J Mol Biol 2013; 425:830-40. [DOI: 10.1016/j.jmb.2012.12.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 10/25/2012] [Accepted: 12/02/2012] [Indexed: 11/21/2022]
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45
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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.
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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.
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46
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Ho D, Lugo MR, Merrill AR. Harmonic analysis of the fluorescence response of bimane adducts of colicin E1 at helices 6, 7, and 10. J Biol Chem 2012; 288:5136-48. [PMID: 23264635 DOI: 10.1074/jbc.m112.436303] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pre-channel state of helices 6, 7, and 10 (Val(447)-Gly(475) and Ile(508)-Ile(522)) of colicin E1 was investigated by a site-directed fluorescence labeling technique. A total of 44 cysteine variants were purified and covalently labeled with monobromobimane fluorescent probe. A variety of fluorescence properties of the bimane fluorophore were measured for both the soluble and membrane-bound states of the channel peptide, including the fluorescence emission maximum, fluorescence anisotropy, and membrane bilayer penetration depth. Using site-directed fluorescence labeling combined with our novel helical periodicity analysis method, the data revealed that helices 6, 7, and 10 are separate amphipathic α-helices with a calculated periodicity of T = 3.34 ± 0.08 for helix 6, T = 3.56 ± 0.03 for helix 7, and T = 2.99 ± 0.12 for helix 10 in the soluble state. In the membrane-bound state, the helical periodicity was determined to be T = 3.00 ± 0.15 for helix 6, T = 3.68 ± 0.03 for helix 7, and T = 3.47 ± 0.04 for helix 10. Dual fluorescence quencher analysis showed that both helices 6 and 7 adopt a tilted topology that correlates well with the analysis based on the fluorescence anisotropy profile. These data provide further support for the umbrella model of the colicin E1 channel domain.
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Affiliation(s)
- Derek Ho
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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47
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Bañó-Polo M, Baeza-Delgado C, Orzáez M, Marti-Renom MA, Abad C, Mingarro I. Polar/Ionizable residues in transmembrane segments: effects on helix-helix packing. PLoS One 2012; 7:e44263. [PMID: 22984481 PMCID: PMC3440369 DOI: 10.1371/journal.pone.0044263] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 07/31/2012] [Indexed: 01/14/2023] Open
Abstract
The vast majority of membrane proteins are anchored to biological membranes through hydrophobic α-helices. Sequence analysis of high-resolution membrane protein structures show that ionizable amino acid residues are present in transmembrane (TM) helices, often with a functional and/or structural role. Here, using as scaffold the hydrophobic TM domain of the model membrane protein glycophorin A (GpA), we address the consequences of replacing specific residues by ionizable amino acids on TM helix insertion and packing, both in detergent micelles and in biological membranes. Our findings demonstrate that ionizable residues are stably inserted in hydrophobic environments, and tolerated in the dimerization process when oriented toward the lipid face, emphasizing the complexity of protein-lipid interactions in biological membranes.
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Affiliation(s)
- Manuel Bañó-Polo
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain
| | - Carlos Baeza-Delgado
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain
| | - Mar Orzáez
- Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Marc A. Marti-Renom
- Genome Biology Group, Structural Genomics Team, Centre Nacional d'Anàlisi Genòmic, Barcelona, Spain
- Structural Genomics Group, Center for Genomic Regulation, Barcelona, Spain
| | - Concepción Abad
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain
| | - Ismael Mingarro
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain
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48
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Abstract
The Bcl-2 family of proteins is formed by pro- and antiapoptotic members. Together they regulate the permeabilization of the mitochondrial outer membrane, a key step in apoptosis. Their complex network of interactions both in the cytosol and on mitochondria determines the fate of the cell. In the past 2 decades, the members of the family have been identified and classified according to their function. Several competing models have been proposed to explain how the Blc-2 proteins orchestrate apoptosis signaling. However, basic aspects of the action of these proteins remain elusive. This review is focused on the biophysical mechanisms that are relevant for their action in apoptosis and on the challenging gaps in our knowledge that necessitate further exploration to finally understand how the Bcl-2 family regulates apoptosis.
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Affiliation(s)
- A J García-Sáez
- Membrane Biophysics, Max Planck Institute for Intelligent Systems, Stuttgart, Germany.
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49
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Zhao K, Zhou H, Zhao X, Wolff DW, Tu Y, Liu H, Wei T, Yang F. Phosphatidic acid mediates the targeting of tBid to induce lysosomal membrane permeabilization and apoptosis. J Lipid Res 2012; 53:2102-2114. [PMID: 22761256 DOI: 10.1194/jlr.m027557] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Upon apoptotic stimuli, lysosomal proteases, including cathepsins and chymotrypsin, are released into cytosol due to lysosomal membrane permeabilization (LMP), where they trigger apoptosis via the lysosomal-mitochondrial pathway of apoptosis. Herein, the mechanism of LMP was investigated. We found that caspase 8-cleaved Bid (tBid) could result in LMP directly. Although Bax or Bak might modestly enhance tBid-triggered LMP, they are not necessary for LMP. To study this further, large unilamellar vesicles (LUVs), model membranes mimicking the lipid constitution of lysosomes, were used to reconstitute the membrane permeabilization process in vitro. We found that phosphatidic acid (PA), one of the major acidic phospholipids found in lysosome membrane, is essential for tBid-induced LMP. PA facilitates the insertion of tBid deeply into lipid bilayers, where it undergoes homo-oligomerization and triggers the formation of highly curved nonbilayer lipid phases. These events induce LMP via pore formation mechanisms because encapsulated fluorescein-conjugated dextran (FD)-20 was released more significantly than FD-70 or FD-250 from LUVs due to its smaller molecular size. On the basis of these data, we proposed tBid-PA interactions in the lysosomal membranes form lipidic pores and result in LMP. We further noted that chymotrypsin-cleaved Bid is more potent than tBid at binding to PA, inserting into the lipid bilayer, and promoting LMP. This amplification mechanism likely contributes to the culmination of apoptotic signaling.
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Affiliation(s)
- Kai Zhao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China
| | - Hejiang Zhou
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China; Graduate University of Chinese Academy of Sciences, Shijingshan District, Beijing 100049, China
| | - Xingyu Zhao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China
| | - Dennis W Wolff
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE 68178; and
| | - Yaping Tu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China; Department of Pharmacology, Creighton University School of Medicine, Omaha, NE 68178; and
| | - Huili Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Taotao Wei
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China.
| | - Fuyu Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China.
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µ-Calpain conversion of antiapoptotic Bfl-1 (BCL2A1) into a prodeath factor reveals two distinct alpha-helices inducing mitochondria-mediated apoptosis. PLoS One 2012; 7:e38620. [PMID: 22745672 PMCID: PMC3379997 DOI: 10.1371/journal.pone.0038620] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Accepted: 05/09/2012] [Indexed: 01/09/2023] Open
Abstract
Anti-apoptotic Bfl-1 and pro-apoptotic Bax, two members of the Bcl-2 family sharing a similar structural fold, are classically viewed as antagonist regulators of apoptosis. However, both proteins were reported to be death inducers following cleavage by the cysteine protease µ-calpain. Here we demonstrate that calpain-mediated cleavage of full-length Bfl-1 induces the release of C-terminal membrane active α-helices that are responsible for its conversion into a pro-apoptotic factor. A careful comparison of the different membrane-active regions present in the Bfl-1 truncated fragments with homologous domains of Bax show that helix α5, but not α6, of Bfl-1 induces cell death and cytochrome c release from purified mitochondria through a Bax/Bak-dependent mechanism. In contrast, both helices α5 and α6 of Bax permeabilize mitochondria regardless of the presence of Bax or Bak. Moreover, we provide evidence that the α9 helix of Bfl-1 promotes cytochrome c release and apoptosis through a unique membrane-destabilizing action whereas Bax-α9 does not display such activities. Hence, despite a common 3D-structure, C-terminal toxic domains present on Bfl-1 and Bax function in a dissimilar manner to permeabilize mitochondria and induce apoptosis. These findings provide insights for designing therapeutic approaches that could exploit the cleavage of endogenous Bcl-2 family proteins or the use of Bfl-1/Bax-derived peptides to promote tumor cell clearance.
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