1
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Miller MS, Cowan AD, Brouwer JM, Smyth ST, Peng L, Wardak AZ, Uren RT, Luo C, Roy MJ, Shah S, Tan Z, Reid GE, Colman PM, Czabotar PE. Sequence differences between BAX and BAK core domains manifest as differences in their interactions with lipids. FEBS J 2024; 291:2335-2353. [PMID: 38088212 DOI: 10.1111/febs.17031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/07/2023] [Accepted: 12/11/2023] [Indexed: 01/21/2024]
Abstract
The B-cell lymphoma 2 (BCL2) family members, BCL2-associated protein X (BAX) and BCL2 homologous antagonist killer (BAK), are required for programmed cell death via the mitochondrial pathway. When cells are stressed, damaged or redundant, the balance of power between the BCL2 family of proteins shifts towards BAX and BAK, allowing their transition from an inactive, monomeric state to a membrane-active oligomeric form that releases cytochrome c from the mitochondrial intermembrane space. That oligomeric state has an essential intermediate, a symmetric homodimer of BAX or BAK. Here we describe crystal structures of dimers of the core domain of BAX, comprising its helices α2-α5. These structures provide an atomic resolution description of the interactions that drive BAX homo-dimerisation and insights into potential interaction between core domain dimers and membrane lipids. The previously identified BAK lipid-interacting sites are not conserved with BAX and are likely to determine the differences between them in their interactions with lipids. We also describe structures of heterodimers of BAK/BAX core domains, yielding further insight into the differences in lipid binding between BAX and BAK.
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Affiliation(s)
- Michelle S Miller
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Angus D Cowan
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Jason M Brouwer
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Sean T Smyth
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
| | - Liuyu Peng
- School of Chemistry, University of Melbourne, Parkville, Vic., Australia
| | - Ahmad Z Wardak
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
| | - Rachel T Uren
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Cindy Luo
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
| | - Michael J Roy
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Sayali Shah
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Ziwen Tan
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Gavin E Reid
- School of Chemistry, University of Melbourne, Parkville, Vic., Australia
- Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, Vic., Australia
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Vic., Australia
| | - Peter M Colman
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
- Department of Medical Biology, University of Melbourne, Parkville, Vic., Australia
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2
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Subas Satish HP, Iyer S, Shi MX, Wong AW, Fischer KC, Wardak AZ, Lio D, Brouwer JM, Uren RT, Czabotar PE, Miller MS, Kluck RM. A novel inhibitory BAK antibody enables assessment of non-activated BAK in cancer cells. Cell Death Differ 2024:10.1038/s41418-024-01289-3. [PMID: 38582955 DOI: 10.1038/s41418-024-01289-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/08/2024] Open
Abstract
BAX and BAK are pro-apoptotic members of the BCL2 family that are required to permeabilize the mitochondrial outer membrane. The proteins can adopt a non-activated monomeric conformation, or an activated conformation in which the exposed BH3 domain facilitates binding either to a prosurvival protein or to another activated BAK or BAX protein to promote pore formation. Certain cancer cells are proposed to have high levels of activated BAK sequestered by MCL1 or BCLXL, thus priming these cells to undergo apoptosis in response to BH3 mimetic compounds that target MCL1 or BCLXL. Here we report the first antibody, 14G6, that is specific for the non-activated BAK conformer. A crystal structure of 14G6 Fab bound to BAK revealed a binding site encompassing both the α1 helix and α5-α6 hinge regions of BAK, two sites involved in the unfolding of BAK during its activation. In mitochondrial experiments, 14G6 inhibited BAK unfolding triggered by three diverse BAK activators, supporting crucial roles for both α1 dissociation and separation of the core (α2-α5) and latch (α6-α9) regions in BAK activation. 14G6 bound the majority of BAK in several leukaemia cell lines, and binding decreased following treatment with BH3 mimetics, indicating only minor levels of constitutively activated BAK in those cells. In summary, 14G6 provides a new means of assessing BAK status in response to anti-cancer treatments.
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Affiliation(s)
- Hema Preethi Subas Satish
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Sweta Iyer
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Melissa X Shi
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Agnes W Wong
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Karla C Fischer
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Ahmad Z Wardak
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Daisy Lio
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Jason M Brouwer
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Rachel T Uren
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Michelle S Miller
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Ruth M Kluck
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia.
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3
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Li ZF, Feng JK, Zhao XC, Liu W, Gu SA, Li R, Lu YL, Mao RJ, Xia LL, Dong LL, Zhang LW, Ruan JY, Liu J, Li GF, Li T, Sun R, Qiu SL, Zheng ZZ, Dong T. The Extract of Pinellia Ternata-Induced Apoptosis of Leukemia Cells by Regulating the Expression of Bax, Bcl-2 and Caspase-3 Protein Expression in Mice. Transplant Proc 2023; 55:2232-2240. [PMID: 37777366 DOI: 10.1016/j.transproceed.2023.08.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/17/2023] [Accepted: 08/01/2023] [Indexed: 10/02/2023]
Abstract
The study aims to lessen the monetary burden on patients and society by decreasing the price of proprietary drugs used in leukemia therapy. Flow cytometry, reverse transcription polymerase chain reaction, western blot, and a patient-derived xenograft mouse model were used to confirm the therapeutic effect of Pinellia ternata extract on leukemia. Three types of leukemia cells (K562, HL-60, and C8166 cell lines) were found to undergo early apoptosis (P ≤ .05) after being exposed to P. ternata extract, as measured by flow cytometry. Reverse transcription polymerase chain reaction results showed that P. ternata extract at both middle (300 μg/mL) and high (500 μg/mL) concentrations was able to down-regulate Bcl-2 and upregulate mRNA expression of Bax and caspase-3. In the patient-derived xenograft mouse model formed by BALB/c-nu/nu nude mice, immunohistochemistry indicated that P. ternata extract effectively suppressed the proliferation of leukemia cells. Therefore, P. ternata extract at 300 μg/mL and 500 μg/mL could effectively inhibit myeloid and lymphocytic leukemia cell proliferation and promote leukemia cell apoptosis by regulating Bax/Bcl-2 and caspase-3.
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Affiliation(s)
- Zheng-Fa Li
- Department of Hematology, Department of Laboratory of the First People's Hospital of Yunnan Province (Affiliated Hospital of Kunming University of Science and Technology), Kunming, Yunnan, China
| | - Jia-Kun Feng
- Department of Hematology, Department of Laboratory of the First People's Hospital of Yunnan Province (Affiliated Hospital of Kunming University of Science and Technology), Kunming, Yunnan, China
| | - Xiao-Chen Zhao
- Yunnan University of Chinese Medicine, Kunming, Yunnan, China
| | - Wei Liu
- Department of Hematology, Department of Laboratory of the First People's Hospital of Yunnan Province (Affiliated Hospital of Kunming University of Science and Technology), Kunming, Yunnan, China
| | - Shi-An Gu
- Department of Hematology, Department of Laboratory of the First People's Hospital of Yunnan Province (Affiliated Hospital of Kunming University of Science and Technology), Kunming, Yunnan, China
| | - Rui Li
- Department of Hematology, Department of Laboratory of the First People's Hospital of Yunnan Province (Affiliated Hospital of Kunming University of Science and Technology), Kunming, Yunnan, China
| | - Yang-Liu Lu
- Yunnan University of Chinese Medicine, Kunming, Yunnan, China
| | - Rui-Jiao Mao
- Department of Hematology, Department of Laboratory of the First People's Hospital of Yunnan Province (Affiliated Hospital of Kunming University of Science and Technology), Kunming, Yunnan, China
| | - Li-Ling Xia
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Lu-Lu Dong
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Li-Wen Zhang
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Jing-Yan Ruan
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Jiao Liu
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Guang-Fen Li
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Tao Li
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Rong Sun
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | - Shui-Lan Qiu
- Department of Hematology, Department of Pathology of Yunnan New Kun Hua Hospital, Kunming, Yunnan, China
| | | | - Ting Dong
- Department of Hematology, Department of Laboratory of the First People's Hospital of Yunnan Province (Affiliated Hospital of Kunming University of Science and Technology), Kunming, Yunnan, China.
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4
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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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Yadav GP, Wang H, Ouwendijk J, Cross S, Wang Q, Qin F, Verkade P, Zhu MX, Jiang QX. Chromogranin B (CHGB) is dimorphic and responsible for dominant anion channels delivered to cell surface via regulated secretion. Front Mol Neurosci 2023; 16:1205516. [PMID: 37435575 PMCID: PMC10330821 DOI: 10.3389/fnmol.2023.1205516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/26/2023] [Indexed: 07/13/2023] Open
Abstract
Regulated secretion is conserved in all eukaryotes. In vertebrates granin family proteins function in all key steps of regulated secretion. Phase separation and amyloid-based storage of proteins and small molecules in secretory granules require ion homeostasis to maintain their steady states, and thus need ion conductances in granule membranes. But granular ion channels are still elusive. Here we show that granule exocytosis in neuroendocrine cells delivers to cell surface dominant anion channels, to which chromogranin B (CHGB) is critical. Biochemical fractionation shows that native CHGB distributes nearly equally in soluble and membrane-bound forms, and both reconstitute highly selective anion channels in membrane. Confocal imaging resolves granular membrane components including proton pumps and CHGB in puncta on the cell surface after stimulated exocytosis. High pressure freezing immuno-EM reveals a major fraction of CHGB at granule membranes in rat pancreatic β-cells. A cryo-EM structure of bCHGB dimer of a nominal 3.5 Å resolution delineates a central pore with end openings, physically sufficient for membrane-spanning and large single channel conductance. Together our data support that CHGB-containing (CHGB+) channels are characteristic of regulated secretion, and function in granule ion homeostasis near the plasma membrane or possibly in other intracellular processes.
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Affiliation(s)
- Gaya P. Yadav
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
| | - Haiyuan Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Joke Ouwendijk
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Stephen Cross
- Wolfson Bioimaging facility, University of Bristol, Bristol, United Kingdom
| | - Qiaochu Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Feng Qin
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Michael X. Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Qiu-Xing Jiang
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
- Cryo-EM Center, Laoshan Laboratory, Qingdao, Shandong, China
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6
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Deng M, He J, Hao C, Guo Y, Si H, Deng X, Zhang C, Li S, Yao S, Ren W, Yao W. EFFECT OF EXOSOMES DERIVED FROM BONE MARROW MESENCHYMAL STEM CELLS ON PROGRAMMED CELL DEATH IN BLAST-INDUCED LUNG INJURY IN RATS. Shock 2023; 59:955-965. [PMID: 37119808 DOI: 10.1097/shk.0000000000002128] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
ABSTRACT Blast lung injuries (BLIs) are frequent because of industrial accidents and terrorist groups. Bone marrow mesenchymal stem cells (BMSCs) and exosomes derived from BMSCs (BMSCs-Exo) have become a hot topic in modern biology because of their significance in damage healing, immune regulation, and gene therapy. The aim of this study is to investigate the effect of BMSCs and BMSCs-Exo on BLI in rats caused by gas explosion. Here, BMSCs and BMSCs-Exo were transplanted into BLI rats via tail vein and then evaluated pathological alterations, oxidative stress, apoptosis, autophagy, and pyroptosis in the lung tissue. Through histopathology and changes in malondialdehyde (MDA) and superoxide dismutase (SOD) contents, we discovered that oxidative stress and inflammatory infiltration in the lungs were significantly reduced by BMSCs and BMSCs-Exo. After treatment with BMSCs and BMSCs-Exo, apoptosis-related proteins, such as cleaved caspase-3 and Bax, were significantly decreased, and the ratio of Bcl-2/Bax was significantly increased; the level of pyroptosis-associated proteins, including NLRP3, GSDMD-N, cleaved caspase-1, IL-1β, and IL-18, were decreased; autophagy-related proteins, beclin-1 and LC3, were downregulated while P62 was upregulated; the number of autophagosomes was decreased. In summary, BMSCs and BMSCs-Exo attenuate BLI caused by gas explosion, which may be associated with apoptosis, aberrant autophagy, and pyroptosis.
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Affiliation(s)
- Meng Deng
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Jing He
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Changfu Hao
- Department of Child and Adolescence Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Yonghua Guo
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Huifang Si
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Xuedan Deng
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Chengpeng Zhang
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Shiyu Li
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Sanqiao Yao
- School of Public Health, Xinxiang Medical University, Xinxiang, China
| | - Wenjie Ren
- Xinxiang Medical University, Xinxiang, China
| | - Wu Yao
- Department of Occupational Health and Environmental Health, College of Public Health, Zhengzhou University, Zhengzhou, China
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7
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Gonzalo Ó, Benedi A, Vela L, Anel A, Naval J, Marzo I. Study of the Bcl-2 Interactome by BiFC Reveals Differences in the Activation Mechanism of Bax and Bak. Cells 2023; 12:cells12050800. [PMID: 36899936 PMCID: PMC10000386 DOI: 10.3390/cells12050800] [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] [Received: 12/02/2022] [Revised: 02/23/2023] [Accepted: 02/28/2023] [Indexed: 03/08/2023] Open
Abstract
Evasion of apoptosis is one of the hallmarks of cancer cells. Proteins of the Bcl-2 family are key regulators of the intrinsic pathway of apoptosis, and alterations in some of these proteins are frequently found in cancer cells. Permeabilization of the outer mitochondrial membrane, regulated by pro- and antiapoptotic members of the Bcl-2 family of proteins, is essential for the release of apoptogenic factors leading to caspase activation, cell dismantlement, and death. Mitochondrial permeabilization depends on the formation of oligomers of the effector proteins Bax and Bak after an activation event mediated by BH3-only proteins and regulated by antiapoptotic members of the Bcl-2 family. In the present work, we have studied interactions between different members of the Bcl-2 family in living cells via the BiFC technique. Despite the limitations of this technique, present data suggest that native proteins of the Bcl-2 family acting inside living cells establish a complex network of interactions, which would fit nicely into "mixed" models recently proposed by others. Furthermore, our results point to differences in the regulation of Bax and Bak activation by proteins of the antiapoptotic and BH3-only subfamilies. We have also applied the BiFC technique to explore the different molecular models proposed for Bax and Bak oligomerization. Bax and Bak's mutants lacking the BH3 domain were still able to associate and give BiFC signals, suggesting the existence of alternative surfaces of interaction between two Bax or Bak molecules. These results agree with the widely accepted symmetric model for the dimerization of these proteins and also suggest that other regions, different from the α6 helix, could be involved in the oligomerization of BH3-in groove dimers.
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8
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Aguilar F, Yu S, Grant RA, Swanson S, Ghose D, Su BG, Sarosiek KA, Keating AE. Peptides from human BNIP5 and PXT1 and non-native binders of pro-apoptotic BAK can directly activate or inhibit BAK-mediated membrane permeabilization. Structure 2023; 31:265-281.e7. [PMID: 36706751 PMCID: PMC9992319 DOI: 10.1016/j.str.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/24/2022] [Accepted: 01/02/2023] [Indexed: 01/27/2023]
Abstract
Apoptosis is important for development and tissue homeostasis, and its dysregulation can lead to diseases, including cancer. As an apoptotic effector, BAK undergoes conformational changes that promote mitochondrial outer membrane disruption, leading to cell death. This is termed "activation" and can be induced by peptides from the human proteins BID, BIM, and PUMA. To identify additional peptides that can regulate BAK, we used computational protein design, yeast surface display screening, and structure-based energy scoring to identify 10 diverse new binders. We discovered peptides from the human proteins BNIP5 and PXT1 and three non-native peptides that activate BAK in liposome assays and induce cytochrome c release from mitochondria. Crystal structures and binding studies reveal a high degree of similarity among peptide activators and inhibitors, ruling out a simple function-determining property. Our results shed light on the vast peptide sequence space that can regulate BAK function and will guide the design of BAK-modulating tools and therapeutics.
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Affiliation(s)
- Fiona Aguilar
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Stacey Yu
- Laboratory of Systems Pharmacology, Harvard Program in Therapeutic Science, Department of Systems Biology, Harvard Medical School, Boston, MA, USA; Program in Molecular and Integrative Physiological Sciences Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA; John B. Little Center for Radiation Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Robert A Grant
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sebastian Swanson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Dia Ghose
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bonnie G Su
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kristopher A Sarosiek
- Laboratory of Systems Pharmacology, Harvard Program in Therapeutic Science, Department of Systems Biology, Harvard Medical School, Boston, MA, USA; Program in Molecular and Integrative Physiological Sciences Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA; John B. Little Center for Radiation Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Amy E Keating
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
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9
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Dai H, Peterson KL, Flatten KS, Meng XW, Venkatachalam A, Correia C, Ramirez-Alvarado M, Pang YP, Kaufmann SH. A BAK subdomain that binds mitochondrial lipids selectively and releases cytochrome C. Cell Death Differ 2023; 30:794-808. [PMID: 36376382 PMCID: PMC9984382 DOI: 10.1038/s41418-022-01083-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 10/20/2022] [Accepted: 10/28/2022] [Indexed: 11/16/2022] Open
Abstract
How BAK and BAX induce mitochondrial outer membrane (MOM) permeabilization (MOMP) during apoptosis is incompletely understood. Here we have used molecular dynamics simulations, surface plasmon resonance, and assays for membrane permeabilization in vitro and in vivo to assess the structure and function of selected BAK subdomains and their derivatives. Results of these studies demonstrate that BAK helical regions α5 and α6 bind the MOM lipid cardiolipin. While individual peptides corresponding to these helical regions lack the full biological activity of BAK, tandem peptides corresponding to α4-α5, α5-α6, or α6-α7/8 can localize exogenous proteins to mitochondria, permeabilize liposomes composed of MOM lipids, and cause MOMP in the absence of the remainder of the BAK protein. Importantly, the ability of these tandem helices to induce MOMP under cell-free conditions is diminished by mutations that disrupt the U-shaped helix-turn-helix structure of the tandem peptides or decrease their lipid binding. Likewise, BAK-induced apoptosis in intact cells is diminished by CLS1 gene interruption, which decreases mitochondrial cardiolipin content, or by BAK mutations that disrupt the U-shaped tandem peptide structure or diminish lipid binding. Collectively, these results suggest that BAK structural rearrangements during apoptosis might mobilize helices involved in specific protein-lipid interactions that are critical for MOMP.
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Affiliation(s)
- Haiming Dai
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA.
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA.
- Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, China.
- Hefei Cancer Hospital, Chinese Academy of Sciences, Hefei, 230031, China.
| | - Kevin L Peterson
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
| | - Karen S Flatten
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
| | - X Wei Meng
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | | | - Cristina Correia
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | | | - Yuan-Ping Pang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | - Scott H Kaufmann
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA.
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA.
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10
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Huang AS, Chin HS, Reljic B, Djajawi TM, Tan IKL, Gong JN, Stroud DA, Huang DCS, van Delft MF, Dewson G. Mitochondrial E3 ubiquitin ligase MARCHF5 controls BAK apoptotic activity independently of BH3-only proteins. Cell Death Differ 2023; 30:632-646. [PMID: 36171332 PMCID: PMC9984372 DOI: 10.1038/s41418-022-01067-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 09/11/2022] [Accepted: 09/13/2022] [Indexed: 11/08/2022] Open
Abstract
Intrinsic apoptosis is principally governed by the BCL-2 family of proteins, but some non-BCL-2 proteins are also critical to control this process. To identify novel apoptosis regulators, we performed a genome-wide CRISPR-Cas9 library screen, and it identified the mitochondrial E3 ubiquitin ligase MARCHF5/MITOL/RNF153 as an important regulator of BAK apoptotic function. Deleting MARCHF5 in diverse cell lines dependent on BAK conferred profound resistance to BH3-mimetic drugs. The loss of MARCHF5 or its E3 ubiquitin ligase activity surprisingly drove BAK to adopt an activated conformation, with resistance to BH3-mimetics afforded by the formation of inhibitory complexes with pro-survival proteins MCL-1 and BCL-XL. Importantly, these changes to BAK conformation and pro-survival association occurred independently of BH3-only proteins and influence on pro-survival proteins. This study identifies a new mechanism by which MARCHF5 regulates apoptotic cell death by restraining BAK activating conformation change and provides new insight into how cancer cells respond to BH3-mimetic drugs. These data also highlight the emerging role of ubiquitin signalling in apoptosis that may be exploited therapeutically.
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Affiliation(s)
- Allan Shuai Huang
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia
| | - Hui San Chin
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia
| | - Boris Reljic
- Bio21 Molecular Science & Biotechnology Institute, 30 Flemington Road, Parkville, Melbourne, 3052, Australia
- Department of Biochemistry and Pharmacology Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia
| | - Tirta M Djajawi
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia
| | - Iris K L Tan
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia
| | - Jia-Nan Gong
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia
- NHC Key Laboratory of Human Disease Comparative Medicine, The Institute of Laboratory Animal Sciences, the Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Beijing Engineering Research Center for Experimental Animal Models of Human Critical Disease, Beijing, China
| | - David A Stroud
- Bio21 Molecular Science & Biotechnology Institute, 30 Flemington Road, Parkville, Melbourne, 3052, Australia
- Department of Biochemistry and Pharmacology Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia
- Murdoch Children's Research Institute, The Royal Children's Hospital, 50 Flemington Road, Parkville, VIC, 3052, Australia
| | - David C S Huang
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia
| | - Mark F van Delft
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia.
| | - Grant Dewson
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia.
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11
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Barisch C, Holthuis JCM, Cosentino K. Membrane damage and repair: a thin line between life and death. Biol Chem 2023; 404:467-490. [PMID: 36810295 DOI: 10.1515/hsz-2022-0321] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/03/2023] [Indexed: 02/24/2023]
Abstract
Bilayered membranes separate cells from their surroundings and form boundaries between intracellular organelles and the cytosol. Gated transport of solutes across membranes enables cells to establish vital ion gradients and a sophisticated metabolic network. However, an advanced compartmentalization of biochemical reactions makes cells also particularly vulnerable to membrane damage inflicted by pathogens, chemicals, inflammatory responses or mechanical stress. To avoid potentially lethal consequences of membrane injuries, cells continuously monitor the structural integrity of their membranes and readily activate appropriate pathways to plug, patch, engulf or shed the damaged membrane area. Here, we review recent insights into the cellular mechanisms that underly an effective maintenance of membrane integrity. We discuss how cells respond to membrane lesions caused by bacterial toxins and endogenous pore-forming proteins, with a primary focus on the intimate crosstalk between membrane proteins and lipids during wound formation, detection and elimination. We also discuss how a delicate balance between membrane damage and repair determines cell fate upon bacterial infection or activation of pro-inflammatory cell death pathways.
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Affiliation(s)
- Caroline Barisch
- Molecular Infection Biology Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
| | - Joost C M Holthuis
- Molecular Cell Biology Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
| | - Katia Cosentino
- Molecular Cell Biophysics Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
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12
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Pore-forming proteins as drivers of membrane permeabilization in cell death pathways. Nat Rev Mol Cell Biol 2022; 24:312-333. [PMID: 36543934 DOI: 10.1038/s41580-022-00564-w] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2022] [Indexed: 12/24/2022]
Abstract
Regulated cell death (RCD) relies on activation and recruitment of pore-forming proteins (PFPs) that function as executioners of specific cell death pathways: apoptosis regulator BAX (BAX), BCL-2 homologous antagonist/killer (BAK) and BCL-2-related ovarian killer protein (BOK) for apoptosis, gasdermins (GSDMs) for pyroptosis and mixed lineage kinase domain-like protein (MLKL) for necroptosis. Inactive precursors of PFPs are converted into pore-forming entities through activation, membrane recruitment, membrane insertion and oligomerization. These mechanisms involve protein-protein and protein-lipid interactions, proteolytic processing and phosphorylation. In this Review, we discuss the structural rearrangements incurred by RCD-related PFPs and describe the mechanisms that manifest conversion from autoinhibited to membrane-embedded molecular states. We further discuss the formation and maturation of membrane pores formed by BAX/BAK/BOK, GSDMs and MLKL, leading to diverse pore architectures. Lastly, we highlight commonalities and differences of PFP mechanisms involving BAX/BAK/BOK, GSDMs and MLKL and conclude with a discussion on how, in a population of challenged cells, the coexistence of cell death modalities may have profound physiological and pathophysiological implications.
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13
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BMSC-Derived Exosomes Alleviate Intervertebral Disc Degeneration by Modulating AKT/mTOR-Mediated Autophagy of Nucleus Pulposus Cells. Stem Cells Int 2022; 2022:9896444. [PMID: 35855812 PMCID: PMC9288351 DOI: 10.1155/2022/9896444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/28/2022] [Accepted: 06/06/2022] [Indexed: 12/14/2022] Open
Abstract
The pathogenesis of intervertebral disc degeneration (IDD) is still unclear. It has been shown that the pathological process of IDD is most closely related to inflammation of nucleus pulposus cells (NPCs), in which inflammatory factors play an important role. Exosomes are the main paracrine mediators and are microvesicles with biological functions similar to those of the cells from which they are derived. Studies have shown that bone mesenchymal stem cells (BMSCs) can inhibit apoptosis of NPCs by sending exosomes as anti-inflammatory and antioxidant, which has been proved to be effective on IDD. However, the specific mechanism of inhibiting apoptosis of NPCs is still unclear. In our study, BMSC-derived exosomes (BMSC-Exo) were isolated from the BMSC culture medium, and their antiapoptotic effects were evaluated in cells and rat models to explore the possible mechanisms. We observed that BMSC-Exo promotes autophagy in NPCs and inhibits the release of inflammatory factors such as IL-1β and TNF-α in LPS-treated NPCs and inhibits apoptosis in NPCs. Further studies showed that BMSC-Exo inhibited the Akt-mTOR pathway. Intramuscular injection of BMSC-Exo alleviates disc degeneration in rat IDD models. In conclusion, our results suggest that BMSC-Exo can reduce NPC apoptosis and alleviate IDD by promoting autophagy by inhibiting the Akt-mTOR pathway. Our study confers a promising therapeutic strategy for IDD.
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14
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At the Crossroads of Life and Death: The Proteins That Influence Cell Fate Decisions. Cancers (Basel) 2022; 14:cancers14112745. [PMID: 35681725 PMCID: PMC9179324 DOI: 10.3390/cancers14112745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 05/30/2022] [Accepted: 05/30/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Cellular senescence and apoptosis were historically thought of as two distinct cell fate pathways. However, many of the proteins involved are integral to both pathways. In particular, the ability of p53 to regulate both senescence and apoptosis meant it was seen as the decisive factor in these decisions, yet questions remain about its ability to select on its own the most appropriate cell fate according to each situation. Therefore, cell fates are no longer considered fixed endpoints but dynamic states that can be shifted given the right combination of activation and/or inhibitions of cofactors. Abstract When a cell is damaged, it must decide how to respond. As a consequence of a variety of stresses, cells can induce well-regulated programmes such as senescence, a persistent proliferative arrest that limits their replication. Alternatively, regulated programmed cell death can be induced to remove the irreversibly damaged cells in a controlled manner. These programmes are mainly triggered and controlled by the tumour suppressor protein p53 and its complex network of effectors, but how it decides between these wildly different responses is not fully understood. This review focuses on the key proteins involved both in the regulation and induction of apoptosis and senescence to examine the key events that determine cell fate following damage. Furthermore, we examine how the regulation and activity of these proteins are altered during the progression of many chronic diseases, including cancer.
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15
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Protein-protein and protein-lipid interactions of pore-forming BCL-2 family proteins in apoptosis initiation. Biochem Soc Trans 2022; 50:1091-1103. [PMID: 35521828 DOI: 10.1042/bst20220323] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 01/26/2023]
Abstract
Apoptosis is a common cell death program that is important in human health and disease. Signaling in apoptosis is largely driven through protein-protein interactions. The BCL-2 family proteins function in protein-protein interactions as key regulators of mitochondrial poration, the process that initiates apoptosis through the release of cytochrome c, which activates the apoptotic caspase cascade leading to cellular demolition. The BCL-2 pore-forming proteins BAK and BAX are the key executors of mitochondrial poration. We review the state of knowledge of protein-protein and protein-lipid interactions governing the apoptotic function of BAK and BAX, as determined through X-ray crystallography and NMR spectroscopy studies. BAK and BAX are dormant, globular α-helical proteins that participate in protein-protein interactions with other pro-death BCL-2 family proteins, transforming them into active, partially unfolded proteins that dimerize and associate with and permeabilize mitochondrial membranes. We compare the protein-protein interactions observed in high-resolution structures with those derived in silico by AlphaFold, making predictions based on combining experimental and in silico approaches to delineate the structural basis for novel protein-protein interaction complexes of BCL-2 family proteins.
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16
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Singh G, Guibao CD, Seetharaman J, Aggarwal A, Grace CR, McNamara DE, Vaithiyalingam S, Waddell MB, Moldoveanu T. Structural basis of BAK activation in mitochondrial apoptosis initiation. Nat Commun 2022; 13:250. [PMID: 35017502 PMCID: PMC8752837 DOI: 10.1038/s41467-021-27851-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 12/14/2021] [Indexed: 12/31/2022] Open
Abstract
BCL-2 proteins regulate mitochondrial poration in apoptosis initiation. How the pore-forming BCL-2 Effector BAK is activated remains incompletely understood mechanistically. Here we investigate autoactivation and direct activation by BH3-only proteins, which cooperate to lower BAK threshold in membrane poration and apoptosis initiation. We define in trans BAK autoactivation as the asymmetric “BH3-in-groove” triggering of dormant BAK by active BAK. BAK autoactivation is mechanistically similar to direct activation. The structure of autoactivated BAK BH3-BAK complex reveals the conformational changes leading to helix α1 destabilization, which is a hallmark of BAK activation. Helix α1 is destabilized and restabilized in structures of BAK engaged by rationally designed, high-affinity activating and inactivating BID-like BH3 ligands, respectively. Altogether our data support the long-standing hit-and-run mechanism of BAK activation by transient binding of BH3-only proteins, demonstrating that BH3-induced structural changes are more important in BAK activation than BH3 ligand affinity. The authors show that the mechanism of BAK activation in mitochondrial apoptosis involves cooperation between direct activation by BH3-only protein BID and BAK autoactivation, providing a unifying basis for BAK triggering by BH3 ligands.
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Affiliation(s)
- Geetika Singh
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA.,Integrative Biomedical Sciences Program, University of Tennessee Health Sciences Center, Memphis, TN, 38163, USA
| | - Cristina D Guibao
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Jayaraman Seetharaman
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Anup Aggarwal
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Christy R Grace
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Dan E McNamara
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | | | - M Brett Waddell
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Tudor Moldoveanu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA. .,Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA.
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17
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Speir M, Chan AH, Simpson DS, Khan T, Saunders TL, Poon IK, Atkin-Smith GK. The Australasian Cell Death Society (ACDS): celebrating 50 years of Australasian cell death research. Immunol Cell Biol 2021; 100:9-14. [PMID: 34761822 DOI: 10.1111/imcb.12510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 10/26/2021] [Indexed: 11/28/2022]
Affiliation(s)
- Mary Speir
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia.,Department of Molecular and Translational Science, Monash University, Clayton, VIC, Australia
| | - Amy H Chan
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, The University of Queensland, St Lucia, QLD, Australia
| | - Daniel S Simpson
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Tashbib Khan
- Beth Israel Deaconess Medical Centre, Harvard Medical School, Boston, MA, USA
| | - Tahnee L Saunders
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Ivan Kh Poon
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC, Australia
| | - Georgia K Atkin-Smith
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC, Australia
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18
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Dong L, Liu F, Liu D, Kang S, Yang X, Wang J. Jolkinolide B attenuates laryngeal cancer cell growth and induces apoptosis via PTEN/PI3K/Akt signaling pathway. In Vitro Cell Dev Biol Anim 2021; 57:786-794. [PMID: 34697781 DOI: 10.1007/s11626-021-00612-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 07/20/2021] [Indexed: 12/24/2022]
Abstract
Jolkinolide B (JB) is a bioactive diterpenoid, isolated from the root of Euphorbia fischeriana Steud, and has been reported to have anti-tumor and anti-inflammation function by regulation of cell migration, invasion, apoptosis, and cell cycle. We aimed to evaluate the effect of JB on laryngeal cancer cells. Human normal larynx epithelial (HBE) cells and cancer cell lines TU212, TU177, and Hep-2 were cultured; MTT assay was used to assess cell proliferation. LY294002 (a PI3K/Akt inhibitor) and IGF-1 (a PI3K/Akt activator) were employed to investigate the expression of PI3K/Akt pathway. Cell migration and invasion activities were detected by scratch wound healing and transwell assay, respectively. Flow cytometry assay was used to assess cell apoptosis. The expression levels of proteins were assessed by immunofluorescence and Western blotting assay. JB inhibited TU212, TU177, and Hep-2 cell viability with an IC50 value of 54.57 ± 0.53 μg/mL, 44.82 ± 0.32 μg/mL, and 49.63 ± 0.47 μg/mL, respectively. Compared with control group, the proliferation, migration, and invasion of cells significantly decreased after JB and LY294002 treatment, while cell apoptosis increased. In IGF-1 group, the results were opposite compared to the JB and LY294002 groups. Western blotting results showed that JB and LY294002 treatment significantly inhibited the levels of Bcl-2, p-PI3K, and p-Akt while the levels of Bax, cleaved caspase-3, and PTEN protein significantly increased. Our study suggested that JB exhibits an inhibition effect on laryngeal cancer cell growth in vitro.
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Affiliation(s)
- Lei Dong
- Department of Otorhinolaryngology Head and Neck Surgery, Yantai Yuhuangding Hospital, No. 20 Yuhuangding East Road, Yantai, 264000, Shandong, China
| | - Feifei Liu
- Department of Otorhinolaryngology Head and Neck Surgery, Yantai Yuhuangding Hospital, No. 20 Yuhuangding East Road, Yantai, 264000, Shandong, China
| | - Dawei Liu
- Department of Otorhinolaryngology Head and Neck Surgery, Yantai Yuhuangding Hospital, No. 20 Yuhuangding East Road, Yantai, 264000, Shandong, China
| | - Shasha Kang
- Department of Otorhinolaryngology Head and Neck Surgery, Yantai Yuhuangding Hospital, No. 20 Yuhuangding East Road, Yantai, 264000, Shandong, China
| | - Xin Yang
- Department of Otorhinolaryngology Head and Neck Surgery, Yantai Yuhuangding Hospital, No. 20 Yuhuangding East Road, Yantai, 264000, Shandong, China.
| | - Junxia Wang
- Department of Otorhinolaryngology, Yantai Haigang Hospital, No. 100 Xingfu Road, Zhifu District, Yantai, 264000, Shandong, China.
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19
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Sandow JJ, Tan IK, Huang AS, Masaldan S, Bernardini JP, Wardak AZ, Birkinshaw RW, Ninnis RL, Liu Z, Dalseno D, Lio D, Infusini G, Czabotar PE, Webb AI, Dewson G. Dynamic reconfiguration of pro-apoptotic BAK on membranes. EMBO J 2021; 40:e107237. [PMID: 34523147 DOI: 10.15252/embj.2020107237] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 12/16/2022] Open
Abstract
BAK and BAX, the effectors of intrinsic apoptosis, each undergo major reconfiguration to an activated conformer that self-associates to damage mitochondria and cause cell death. However, the dynamic structural mechanisms of this reconfiguration in the presence of a membrane have yet to be fully elucidated. To explore the metamorphosis of membrane-bound BAK, we employed hydrogen-deuterium exchange mass spectrometry (HDX-MS). The HDX-MS profile of BAK on liposomes comprising mitochondrial lipids was consistent with known solution structures of inactive BAK. Following activation, HDX-MS resolved major reconfigurations in BAK. Mutagenesis guided by our HDX-MS profiling revealed that the BCL-2 homology (BH) 4 domain maintains the inactive conformation of BAK, and disrupting this domain is sufficient for constitutive BAK activation. Moreover, the entire N-terminal region preceding the BAK oligomerisation domains became disordered post-activation and remained disordered in the activated oligomer. Removal of the disordered N-terminus did not impair, but rather slightly potentiated, BAK-mediated membrane permeabilisation of liposomes and mitochondria. Together, our HDX-MS analyses reveal new insights into the dynamic nature of BAK activation on a membrane, which may provide new opportunities for therapeutic targeting.
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Affiliation(s)
- Jarrod J Sandow
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Iris Kl Tan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Alan S Huang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Shashank Masaldan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Jonathan P Bernardini
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Ahmad Z Wardak
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
| | - Richard W Birkinshaw
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Robert L Ninnis
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Ziyan Liu
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Destiny Dalseno
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Daisy Lio
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia
| | - Giuseppi Infusini
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Andrew I Webb
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
| | - Grant Dewson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Vic., Australia
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20
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Sperl LE, Rührnößl F, Schiller A, Haslbeck M, Hagn F. High-resolution analysis of the conformational transition of pro-apoptotic Bak at the lipid membrane. EMBO J 2021; 40:e107159. [PMID: 34523144 PMCID: PMC8521305 DOI: 10.15252/embj.2020107159] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 08/09/2021] [Accepted: 08/20/2021] [Indexed: 12/21/2022] Open
Abstract
Permeabilization of the outer mitochondrial membrane by pore-forming Bcl2 proteins is a crucial step for the induction of apoptosis. Despite a large set of data suggesting global conformational changes within pro-apoptotic Bak during pore formation, high-resolution structural details in a membrane environment remain sparse. Here, we used NMR and HDX-MS (Hydrogen deuterium exchange mass spectrometry) in lipid nanodiscs to gain important high-resolution structural insights into the conformational changes of Bak at the membrane that are dependent on a direct activation by BH3-only proteins. Furthermore, we determined the first high-resolution structure of the Bak transmembrane helix. Upon activation, α-helix 1 in the soluble domain of Bak dissociates from the protein and adopts an unfolded and dynamic potentially membrane-bound state. In line with this finding, comparative protein folding experiments with Bak and anti-apoptotic BclxL suggest that α-helix 1 in Bak is a metastable structural element contributing to its pro-apoptotic features. Consequently, mutagenesis experiments aimed at stabilizing α-helix 1 yielded Bak variants with delayed pore-forming activity. These insights will contribute to a better mechanistic understanding of Bak-mediated membrane permeabilization.
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Affiliation(s)
- Laura E Sperl
- Bavarian NMR Center at the Department of ChemistryTechnical University of MunichGarchingGermany
- Institute of Structural BiologyHelmholtz Zentrum MünchenNeuherbergGermany
| | - Florian Rührnößl
- Center for Functional Protein Assemblies and Department of ChemistryTechnical University of MunichGarchingGermany
| | - Anita Schiller
- Bavarian NMR Center at the Department of ChemistryTechnical University of MunichGarchingGermany
- Institute of Structural BiologyHelmholtz Zentrum MünchenNeuherbergGermany
| | - Martin Haslbeck
- Center for Functional Protein Assemblies and Department of ChemistryTechnical University of MunichGarchingGermany
| | - Franz Hagn
- Bavarian NMR Center at the Department of ChemistryTechnical University of MunichGarchingGermany
- Institute of Structural BiologyHelmholtz Zentrum MünchenNeuherbergGermany
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21
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Li K, van Delft MF, Dewson G. Too much death can kill you: inhibiting intrinsic apoptosis to treat disease. EMBO J 2021; 40:e107341. [PMID: 34037273 DOI: 10.15252/embj.2020107341] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/11/2021] [Accepted: 03/18/2021] [Indexed: 02/06/2023] Open
Abstract
Apoptotic cell death is implicated in both physiological and pathological processes. Since many types of cancerous cells intrinsically evade apoptotic elimination, induction of apoptosis has become an attractive and often necessary cancer therapeutic approach. Conversely, some cells are extremely sensitive to apoptotic stimuli leading to neurodegenerative disease and immune pathologies. However, due to several challenges, pharmacological inhibition of apoptosis is still only a recently emerging strategy to combat pathological cell loss. Here, we describe several key steps in the intrinsic (mitochondrial) apoptosis pathway that represent potential targets for inhibitors in disease contexts. We also discuss the mechanisms of action, advantages and limitations of small-molecule and peptide-based inhibitors that have been developed to date. These inhibitors serve as important research tools to dissect apoptotic signalling and may foster new treatments to reduce unwanted cell loss.
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Affiliation(s)
- Kaiming Li
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Department of Medical Biology, University of Melbourne, Royal Parade, Melbourne, VIC, Australia
| | - Mark F van Delft
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Department of Medical Biology, University of Melbourne, Royal Parade, Melbourne, VIC, Australia
| | - Grant Dewson
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Department of Medical Biology, University of Melbourne, Royal Parade, Melbourne, VIC, Australia
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22
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Birkinshaw RW, Iyer S, Lio D, Luo CS, Brouwer JM, Miller MS, Robin AY, Uren RT, Dewson G, Kluck RM, Colman PM, Czabotar PE. Structure of detergent-activated BAK dimers derived from the inert monomer. Mol Cell 2021; 81:2123-2134.e5. [PMID: 33794146 DOI: 10.1016/j.molcel.2021.03.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 01/11/2021] [Accepted: 03/09/2021] [Indexed: 01/27/2023]
Abstract
A body of data supports the existence of core (α2-α5) dimers of BAK and BAX in the oligomeric, membrane-perturbing conformation of these essential apoptotic effector molecules. Molecular structures for these dimers have only been captured for truncated constructs encompassing the core domain alone. Here, we report a crystal structure of BAK α2-α8 dimers (i.e., minus its flexible N-terminal helix and membrane-anchoring C-terminal segment) that has been obtained through the activation of monomeric BAK with the detergent C12E8. Core dimers are evident, linked through the crystal by contacts via latch (α6-α8) domains. This crystal structure shows activated BAK dimers with the extended latch domain present. Our data provide direct evidence for the conformational change converting BAK from inert monomer to the functional dimer that destroys mitochondrial integrity. This dimer is the smallest functional unit for recombinant BAK or BAX described so far.
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Affiliation(s)
- Richard W Birkinshaw
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia.
| | - Sweta Iyer
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Daisy Lio
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Cindy S Luo
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Jason M Brouwer
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Michelle S Miller
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Adeline Y Robin
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Rachel T Uren
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Grant Dewson
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Ruth M Kluck
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Peter M Colman
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia.
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23
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Targeting BCL-2 in Cancer: Advances, Challenges, and Perspectives. Cancers (Basel) 2021; 13:cancers13061292. [PMID: 33799470 PMCID: PMC8001391 DOI: 10.3390/cancers13061292] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/08/2021] [Accepted: 03/10/2021] [Indexed: 12/19/2022] Open
Abstract
Simple Summary Apoptosis, a programmed form of cell death, represents the main mechanism by which cells die. Such phenomenon is highly regulated by the BCL-2 family of proteins, which includes both pro-apoptotic and pro-survival proteins. The decision whether cells live or die is tightly controlled by a balance between these two classes of proteins. Notably, the pro-survival Bcl-2 proteins are frequently overexpressed in cancer cells dysregulating this balance in favor of survival and also rendering cells more resistant to therapeutic interventions. In this review, we outlined the most important steps in the development of targeting the BCL-2 survival proteins, which laid the ground for the discovery and the development of the selective BCL-2 inhibitor venetoclax as a therapeutic drug in hematological malignancies. The limitations and future directions are also discussed. Abstract The major form of cell death in normal as well as malignant cells is apoptosis, which is a programmed process highly regulated by the BCL-2 family of proteins. This includes the antiapoptotic proteins (BCL-2, BCL-XL, MCL-1, BCLW, and BFL-1) and the proapoptotic proteins, which can be divided into two groups: the effectors (BAX, BAK, and BOK) and the BH3-only proteins (BIM, BAD, NOXA, PUMA, BID, BIK, HRK). Notably, the BCL-2 antiapoptotic proteins are often overexpressed in malignant cells. While this offers survival advantages to malignant cells and strengthens their drug resistance capacity, it also offers opportunities for novel targeted therapies that selectively kill such cells. This review provides a comprehensive overview of the extensive preclinical and clinical studies targeting BCL-2 proteins with various BCL-2 proteins inhibitors with emphasis on venetoclax as a single agent, as well as in combination with other therapeutic agents. This review also discusses recent advances, challenges focusing on drug resistance, and future perspectives for effective targeting the Bcl-2 family of proteins in cancer.
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Zhang Z, Huang B, Zhang XC, Lin J. Cysteine-based crosslinking approach for characterization of oligomeric pore-forming proteins in the mitochondrial membranes. Methods Enzymol 2021; 649:371-396. [PMID: 33712193 DOI: 10.1016/bs.mie.2021.01.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Mitochondria are important not only to healthy but also dying cells. In particular, apoptotic cell death initiates when the mitochondrial outer membrane is permeabilized by Bax, a protein of the Bcl-2 family. Bax shares a structural fold with some α-helical bacterial pore-forming toxins before these proteins actively engage membranes. Despite decades of intensive research, the structures of the pores formed by these proteins are mostly unknown, mainly because the pores are assembled by different numbers of the proteins whose conformation and interaction are highly dynamic. Site-specific crosslinking of the pore-forming proteins in cellular membranes where the pores are assembled is a powerful approach to assess the biological pore structure, dynamics and function. In this chapter, we describe a cysteine-based site-specific crosslinking protocol for the Bax protein in the mitochondrial membrane. We discuss the expected results and the resulting structural-functional models for the pore-forming Bax oligomer, in comparison with other crosslinking approaches that have been used to study other mitochondrial protein complexes. At the end, we highlight the advantages of the crosslinking approaches as well as the limitations and alternative approaches.
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Affiliation(s)
- Zhi Zhang
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Bo Huang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xuejun C Zhang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jialing Lin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
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25
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Quarleri J, Cevallos C, Delpino MV. Apoptosis in infectious diseases as a mechanism of immune evasion and survival. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 125:1-24. [PMID: 33931136 DOI: 10.1016/bs.apcsb.2021.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In pluricellular organisms, apoptosis is indispensable for the development and homeostasis. During infection, apoptosis plays the main role in the elimination of infected cells. Infectious diseases control apoptosis, and this contributes to disease pathogenesis. Increased apoptosis may participate in two different ways. It can assist the dissemination of intracellular pathogens or induce immunosuppression to favor pathogen dissemination. In other conditions, apoptosis can benefit eradicate infectious agents from the host. Accordingly, bacteria, viruses, fungi, and parasites have developed strategies to inhibit host cell death by apoptosis to allow intracellular survival and persistence of the pathogen. The clarification of the intracellular signaling pathways, the receptors involved and the pathogen factors that interfere with apoptosis could disclose new therapeutic targets for blocking microbial actions on apoptotic pathways. In this review, we summarize the current knowledge on pathogen anti-apoptotic and apoptotic approaches and the mechanisms involving in disease.
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Affiliation(s)
- Jorge Quarleri
- Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Cintia Cevallos
- Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - María Victoria Delpino
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina.
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26
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Abstract
Recent experiments have shown that certain molecular agents can selectively penetrate and aggregate in bacterial lipid membranes, leading to their permeability and rupture. To help reveal and understand the underlying mechanisms, here we establish a theory to show that the deformation energy of the membrane tends to limit the growth of molecular domains on a lipid membrane, resulting in a characteristic domain size, and that the domain aggregation significantly reduces the energy barrier to pore growth. Coarse-grained molecular dynamics simulations are performed to validate such domain aggregation and associated pore formation. This study sheds light on how lipid membranes can be damaged through molecular domain aggregation and contributes to establish a theoretical foundation for the next-generation membrane-targeting nanomedicine.
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Affiliation(s)
- Yue Liu
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Guijin Zou
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore
| | - Huajian Gao
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 639798, Singapore
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27
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Du R, Wu N, Li L. Aberrantly Expressed Non-Coding RNAs in the Placenta and Their Role in the Pathophysiology of Gestational Diabetes Mellitus. Diabetes Metab Syndr Obes 2021; 14:3719-3732. [PMID: 34456579 PMCID: PMC8387639 DOI: 10.2147/dmso.s325993] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/12/2021] [Indexed: 11/23/2022] Open
Abstract
Gestational diabetes mellitus (GDM), one of the most common complications during pregnancy, is associated with a high risk of short- and long-term adverse effects on the mother and offspring. Placenta-derived hormones and cytokines aggravate maternal insulin resistance (IR) during pregnancy, which in turn contribute to GDM. The hyperglycemia and IR in GDM result in aberrant placental structure and function adversely affecting fetal growth and well-being. Therefore, it is reasonable to assume that structural and functional alterations in the placenta contribute to the pathogenesis of GDM and GDM-related complications. Increasing evidence suggests that multiple non-coding RNAs (ncRNAs), including microRNAs, long non-coding RNAs, and circular RNAs, are dysregulated in placentas of patients with GDM and linked to abnormal placental structure, metabolism, and function. Manipulation of ncRNA expression led to some key pathophysiological features of GDM, such as trophoblast dysfunction, changes in intracellular glucose metabolism, and inflammation. Moreover, placenta-specific ncRNAs may be potential diagnostic biomarkers and even therapeutic targets for GDM. This review summarizes data published on the involvement of aberrantly expressed placental ncRNAs in GDM and provides information on their role in the pathogenesis of GDM and GDM-associated complications.
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Affiliation(s)
- Runyu Du
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
| | - Na Wu
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
| | - Ling Li
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
- Correspondence: Ling Li Department of Endocrinology, Shengjing Hospital of China Medical University, No. 36, Sanhao Street, Heping District, Shenyang, Liaoning Province, 110004, People’s Republic of ChinaTel +86 18940251181Fax +86 24-25944460 Email
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28
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Li Y, Zhuang J. miR-345-3p serves a protective role during gestational diabetes mellitus by targeting BAK1. Exp Ther Med 2020; 21:2. [PMID: 33235611 PMCID: PMC7678625 DOI: 10.3892/etm.2020.9434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 03/18/2020] [Indexed: 02/07/2023] Open
Abstract
Recent studies have demonstrated that microRNAs (miRs) serve a crucial role during the development of gestational diabetes mellitus (GDM). However, the mechanisms underlying miR-345-3p and its protective role during GDM have not been previously reported. The present study investigated miR-345-3p expression and function in vitro, and the possible molecular mechanisms underlying GDM. Compared with healthy pregnant women, miR-345-3p was downregulated in the placental tissue and peripheral blood of patients with GDM. Further investigation revealed that BCL2-antagonist/killer 1 (BAK1) was a predicted target gene of miR-345-3p, and the expression of BAK1 was significantly increased in patients with GDM compared with healthy pregnant women. In vitro analysis revealed that miR-345-3p mimic significantly increased cell viability, migration and invasion, inhibited apoptosis, upregulated Bcl-2 and matrix metallopeptidase 9 expression, and decreased Bax expression compared with the control group. Furthermore, miR-245-3p mimic-induced alterations were reversed by BAK1 overexpression. The results suggested that miR-345-3p overexpression exhibited a protective role in patients with GDM by inhibiting HTR8-/SVneo cell apoptosis, and promoting cell proliferation and migration via targeting BAK1. The use of miR-345-3p for the diagnosis of GDM requires further investigation.
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Affiliation(s)
- Yuxia Li
- Department of Gynecology and Obstetrics, Wuhan Children's Hospital, Wuhan Maternal and Child Healthcare Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430010, P.R. China
| | - Jun Zhuang
- Department of Obstetrics, Lianshui County People's Hospital, Huai'an, Jiangsu 223400, P.R. China
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29
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Cowan AD, Smith NA, Sandow JJ, Kapp EA, Rustam YH, Murphy JM, Brouwer JM, Bernardini JP, Roy MJ, Wardak AZ, Tan IK, Webb AI, Gulbis JM, Smith BJ, Reid GE, Dewson G, Colman PM, Czabotar PE. BAK core dimers bind lipids and can be bridged by them. Nat Struct Mol Biol 2020; 27:1024-1031. [DOI: 10.1038/s41594-020-0494-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 07/31/2020] [Indexed: 12/27/2022]
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30
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Robust autoactivation for apoptosis by BAK but not BAX highlights BAK as an important therapeutic target. Cell Death Dis 2020; 11:268. [PMID: 32327636 PMCID: PMC7181796 DOI: 10.1038/s41419-020-2463-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/05/2020] [Accepted: 04/06/2020] [Indexed: 02/08/2023]
Abstract
BAK and BAX, which drive commitment to apoptosis, are activated principally by certain BH3-only proteins that bind them and trigger major rearrangements. One crucial conformation change is exposure of their BH3 domain which allows BAK or BAX to form homodimers, and potentially to autoactivate other BAK and BAX molecules to ensure robust pore formation and cell death. Here, we test whether full-length BAK or mitochondrial BAX that are specifically activated by antibodies can then activate other BAK or BAX molecules. We found that antibody-activated BAK efficiently activated BAK as well as mitochondrial or cytosolic BAX, but antibody-activated BAX unexpectedly proved a poor activator. Notably, autoactivation by BAK involved transient interactions, as BAK and BAX molecules it activated could dissociate and homodimerize. The results suggest that BAK-driven autoactivation may play a substantial role in apoptosis, including recruitment of BAX to the mitochondria. Hence, directly targeting BAK rather than BAX may prove particularly effective in inhibiting unwanted apoptosis, or alternatively, inducing apoptosis in cancer cells.
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31
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Moldoveanu T, Czabotar PE. BAX, BAK, and BOK: A Coming of Age for the BCL-2 Family Effector Proteins. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a036319. [PMID: 31570337 DOI: 10.1101/cshperspect.a036319] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The BCL-2 family of proteins control a key checkpoint in apoptosis, that of mitochondrial outer membrane permeabilization or, simply, mitochondrial poration. The family consists of three subgroups: BH3-only initiators that respond to apoptotic stimuli; antiapoptotic guardians that protect against cell death; and the membrane permeabilizing effectors BAX, BAK, and BOK. On activation, effector proteins are converted from inert monomers into membrane permeabilizing oligomers. For many years, this process has been poorly understood at the molecular level, but a number of recent advances have provided important insights. We review the regulation of these effectors, their activation, subsequent conformational changes, and the ensuing oligomerization events that enable mitochondrial poration, which initiates apoptosis through release of key signaling factors such as cytochrome c We highlight the mysteries that remain in understanding these important proteins in an endeavor to provide a comprehensive picture of where the field currently sits and where it is moving toward.
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Affiliation(s)
- Tudor Moldoveanu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.,Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis Tennessee 38105, USA
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, University of Melbourne, Parkville, Victoria 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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Attenuation of Equine Lentivirus Alters Mitochondrial Protein Expression Profile from Inflammation to Apoptosis. J Virol 2019; 93:JVI.00653-19. [PMID: 31391270 DOI: 10.1128/jvi.00653-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/23/2019] [Indexed: 12/18/2022] Open
Abstract
Equine infectious anemia virus (EIAV) is an equine lentivirus similar to HIV-1, targets host immune cells, and causes a life-long infection in horses. The Chinese live EIAV vaccine is attenuated from long-term passaging of a highly virulent strain in vitro The parent pathogenic strain (EIAVDLV34) induces a host inflammatory storm to cause severe pathological injury of animals. However, the vaccine strain (EIAVDLV121) induces a high level of apoptosis to eliminate infected cells. To investigate how these processes are regulated, we performed a comparative proteomics analysis and functional study in equine monocyte-derived macrophages (eMDMs) and found that the divergent mitochondrial protein expression profiles caused by EIAV strains with different virulence led to disparate mitochondrial function, morphology, and metabolism. This in turn promoted the distinct transformation of macrophage inflammatory polarization and intrinsic apoptosis. In EIAVDLV34-infected cells, a high level of glycolysis and increased mitochondrial fragmentation were induced, resulting in the M1-polarized proinflammatory-type transformation of macrophages and the subsequent production of a strong inflammatory response. Following infection with EIAVDLV121, the infected cells were transformed into M2-polarized anti-inflammatory macrophages by inhibition of glycolysis. In this case, a decrease in the mitochondrial membrane potential and impairment of the electron transport chain led to increased levels of apoptosis and reactive oxygen species. These results correlated with viral pathogenicity loss and may help provide an understanding of the key mechanism of lentiviral attenuation.IMPORTANCE Following viral infection, the working pattern and function of the cell can be transformed through the impact on mitochondria. It still unknown how the mitochondrial response changes in cells infected with viruses in the process of virulence attenuation. EIAVDLV121 is the only effective lentiviral vaccine for large-scale use in the world. EIAVDLV34 is the parent pathogenic strain. Unlike EIAVDLV34-induced inflammation storms, EIAVDLV121 can induce high levels of apoptosis. For the first time, we found that, after the mitochondrial protein expression profile is altered, EIAVDLV34-infected cells are transformed into M1-polarized-type macrophages and cause inflammatory injury and that the intrinsic apoptosis pathway is activated in EIAVDLV121-infected cells. These studies shed light on how the mitochondrial protein expression profile changes between cells infected by pathogenic lentivirus strains and cells infected by attenuated lentivirus strains to drive different cellular responses, especially from inflammation to apoptosis.
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A new perspective on membrane-embedded Bax oligomers using DEER and bioresistant orthogonal spin labels. Sci Rep 2019; 9:13013. [PMID: 31506457 PMCID: PMC6737250 DOI: 10.1038/s41598-019-49370-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 08/20/2019] [Indexed: 12/23/2022] Open
Abstract
Bax is a Bcl-2 protein crucial for apoptosis initiation and execution, whose active conformation is only partially understood. Dipolar EPR spectroscopy has proven to be a valuable tool to determine coarse-grained models of membrane-embedded Bcl-2 proteins. Here we show how the combination of spectroscopically distinguishable nitroxide and gadolinium spin labels and Double Electron-Electron Resonance can help to gain new insights into the quaternary structure of active, membrane-embedded Bax oligomers. We show that attaching labels bulkier than the conventional MTSL may affect Bax fold and activity, depending on the protein/label combination. However, we identified a suitable pair of spectroscopically distinguishable labels, which allows to study complex distance networks in the oligomers that could not be disentangled before. Additionally, we compared the stability of the different spin-labeled protein variants in E. coli and HeLa cell extracts. We found that the gem-diethyl nitroxide-labeled Bax variants were reasonably stable in HeLa cell extracts. However, when transferred into human cells, Bax was found to be mislocalized, thus preventing its characterization in a physiological environment. The successful use of spectroscopically distinguishable labels on membrane-embedded Bax-oligomers opens an exciting new path towards structure determination of membrane-embedded homo- or hetero-oligomeric Bcl-2 proteins via EPR.
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34
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Wang B, Mai Z, Du M, Wang L, Yang F, Ma Y, Wang X, Chen T. BCL-XL directly retrotranslocates the monomeric BAK. Cell Signal 2019; 61:1-9. [DOI: 10.1016/j.cellsig.2019.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 05/02/2019] [Accepted: 05/02/2019] [Indexed: 02/07/2023]
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健愉 冯, 玉山 朱, 陈 权, 凌 林, Jianyu F, Yushan Z, Quan C, Jialing L. [Physiological Function and Structural Basis of Bcl-2 Family Proteins]. ZHONGGUO XI BAO SHENG WU XUE XUE BAO 2019; 41:1477-1489. [PMID: 34249113 PMCID: PMC8265309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Apoptosis is an important biological process that plays a key role in the regulation of cell fate and homeostasis. The B-cell lymphoma-2 (Bcl-2) family proteins are important regulators of the apoptotic pathway, and their dysfunction is associated with a variety of diseases, including cancer, neurodegenerative and autoimmune diseases. In the past decade, a large number of research work on the physiological functions and atomic structures of Bcl-2 family proteins have been reported, which has deepened our understanding of the molecular mechanism and pathological significance of Bcl-2 family proteins. Recently, new drugs targeting different Bcl-2 proteins have been developed and used in clinics or tested in clinical trials. However, the complexity and diversity in functions and structures of Bcl-2 family have left many unsolved problems. This article summarizes current knowledge of the structure and function of Bcl-2 family proteins and discusses the pharmacological significance of Bcl-2 proteins as effective therapeutic targets.
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Affiliation(s)
| | | | | | - 林家 凌
- 俄克拉荷马大学健康科学中心生物化学与分子生物学系, 俄克拉何马城 73126-0901
| | - Feng Jianyu
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Zhu Yushan
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Chen Quan
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Lin Jialing
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma 73126, USA
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36
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Naderer T, Fulcher MC. Targeting apoptosis pathways in infections. J Leukoc Biol 2019; 103:275-285. [PMID: 29372933 DOI: 10.1189/jlb.4mr0717-286r] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/29/2017] [Accepted: 09/13/2017] [Indexed: 11/24/2022] Open
Abstract
The programmed cell death pathway of apoptosis is essential for mammalian development and immunity as it eliminates unwanted and dangerous cells. As part of the cellular immune response, apoptosis removes the replicative niche of intracellular pathogens and enables the resolution of infections. To subvert apoptosis, pathogens have evolved a diverse range of mechanisms. In some circumstances, however, pathogens express effector molecules that induce apoptotic cell death. In this review, we focus on selected host-pathogen interactions that affect apoptotic pathways. We discuss how pathogens control the fate of host cells and how this determines the outcome of infections. Finally, small molecule inhibitors that activate apoptosis in cancer cells can also induce apoptotic cell death of infected cells. This suggests that targeting host death factors to kill infected cells is a potential therapeutic option to treat infectious diseases.
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Affiliation(s)
- Thomas Naderer
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Australia
| | - Maria Cecilia Fulcher
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Australia
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37
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Ader NR, Hoffmann PC, Ganeva I, Borgeaud AC, Wang C, Youle RJ, Kukulski W. Molecular and topological reorganizations in mitochondrial architecture interplay during Bax-mediated steps of apoptosis. eLife 2019; 8:40712. [PMID: 30714902 PMCID: PMC6361589 DOI: 10.7554/elife.40712] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 01/22/2019] [Indexed: 12/25/2022] Open
Abstract
During apoptosis, Bcl-2 proteins such as Bax and Bak mediate the release of pro-apoptotic proteins from the mitochondria by clustering on the outer mitochondrial membrane and thereby permeabilizing it. However, it remains unclear how outer membrane openings form. Here, we combined different correlative microscopy and electron cryo-tomography approaches to visualize the effects of Bax activity on mitochondria in human cells. Our data show that Bax clusters localize near outer membrane ruptures of highly variable size. Bax clusters contain structural elements suggesting a higher order organization of their components. Furthermore, unfolding of inner membrane cristae is coupled to changes in the supramolecular assembly of ATP synthases, particularly pronounced at membrane segments exposed to the cytosol by ruptures. Based on our results, we propose a comprehensive model in which molecular reorganizations of the inner membrane and sequestration of outer membrane components into Bax clusters interplay in the formation of outer membrane ruptures. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Nicholas R Ader
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Patrick C Hoffmann
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Iva Ganeva
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Alicia C Borgeaud
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Chunxin Wang
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Wanda Kukulski
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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38
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Abstract
During apoptosis, mitochondria permeabilize the outer membranes to release apoptogenic proteins from the intermembrane space. This process termed mitochondrial outer membrane permeabilization (MOMP) is regulated by Bcl-2 family proteins. Bax is an effector proapoptotic molecule that permeabilizes the lipid membranes when it is activated by activator BH3-only proteins. We investigated this critical event by developing simple but faithful vesicle systems-outer membrane vesicles (OMVs) and liposomes-to visualize the pores in the membrane by using cryo-electron microscopy (cryo-EM). We have revealed the morphology of the pore, determined the localization of Bax labeled with nanogold and have performed image analysis to help understand the mechanisms of pore formation induced by Bax.
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Affiliation(s)
- Tomomi Kuwana
- La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA.
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39
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Iyer S, Uren RT, Kluck RM. Probing BAK and BAX Activation and Pore Assembly with Cytochrome c Release, Limited Proteolysis, and Oxidant-Induced Linkage. Methods Mol Biol 2019; 1877:201-216. [PMID: 30536008 DOI: 10.1007/978-1-4939-8861-7_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Mitochondrial permeabilization is a key event in the intrinsic pathway of apoptosis, and is mediated by either of the BCL-2 family members BAK or BAX. These two proteins generate pores in the mitochondrial outer membrane that release factors such as cytochrome c into the cytosol to trigger caspase activation and apoptotic cell death. To generate pores, BAK and BAX undergo major changes including BAX translocation to the outer membrane, and partial unfolding, dimerization, and oligomerization. Here we describe biochemical protocols that can be used on most cell types to gain a population overview of BAK and BAX status.
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Affiliation(s)
- Sweta Iyer
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Rachel T Uren
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Ruth M Kluck
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia.
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40
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Topology of active, membrane-embedded Bax in the context of a toroidal pore. Cell Death Differ 2018; 25:1717-1731. [PMID: 30185826 DOI: 10.1038/s41418-018-0184-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/20/2018] [Accepted: 05/21/2018] [Indexed: 01/18/2023] Open
Abstract
Bax is a Bcl-2 protein critical for apoptosis induction. In healthy cells, Bax is mostly a monomeric, cytosolic protein, while upon apoptosis initiation it inserts into the outer mitochondrial membrane, oligomerizes, and forms pores that release proapoptotic factors like Cytochrome c into the cytosol. The structures of active Bax and its homolog Bak are only partially understood and the topology of the proteins with respect to the membrane bilayer is controversially described in the literature. Here, we systematically review and examine the protein-membrane, protein-water, and protein-protein contacts of the nine helices of active Bax and Bak, and add a new set of topology data obtained by fluorescence and EPR methods. We conclude based on the consistent part of the datasets that the core/dimerization domain of Bax (Bak) is water exposed with only helices 4 and 5 in membrane contact, whereas the piercing/latch domain is in peripheral membrane contact, with helix 9 being transmembrane. Among the available structural models, those considering the dimerization/core domain at the rim of a toroidal pore are the most plausible to describe the active state of the proteins, although the structural flexibility of the piercing/latch domain does not allow unambiguous discrimination between the existing models.
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41
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Cosentino K, García-Sáez AJ. MIM through MOM: the awakening of Bax and Bak pores. EMBO J 2018; 37:embj.2018100340. [PMID: 30135068 DOI: 10.15252/embj.2018100340] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
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42
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Lai YC, Li CC, Sung TC, Chang CW, Lan YJ, Chiang YW. The role of cardiolipin in promoting the membrane pore-forming activity of BAX oligomers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:268-280. [PMID: 29958826 DOI: 10.1016/j.bbamem.2018.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 06/17/2018] [Accepted: 06/22/2018] [Indexed: 01/31/2023]
Abstract
BCL-2-associated X (BAX) protein acts as a gatekeeper in regulating mitochondria-dependent apoptosis. Under cellular stress, BAX becomes activated and transforms into a lethal oligomer that causes mitochondrial outer membrane permeabilization (MOMP). Previous studies have identified several structural features of the membrane-associated BAX oligomer; they include the formation of the BH3-in-groove dimer, the collapse of the helical hairpin α5-α6, and the membrane insertion of α9 helix. However, it remains unclear as to the role of lipid environment in determining the conformation and the pore-forming activity of the BAX oligomers. Here we study molecular details of the membrane-associated BAX in various lipid environments using fluorescence and ESR techniques. We identify the inactive versus active forms of membrane-associated BAX, only the latter of which can induce stable and large membrane pores that are sufficient in size to pass apoptogenic factors. We reveal that the presence of CL is crucial to promoting the association between BAX dimers, hence the active oligomers. Without the presence of CL, BAX dimers assemble into an inactive oligomer that lacks the ability to form stable pores in the membrane. This study suggests an important role of CL in determining the formation of active BAX oligomers.
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Affiliation(s)
- Yei-Chen Lai
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chieh-Chin Li
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Tai-Ching Sung
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chia-Wei Chang
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yu-Jing Lan
- 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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43
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Jeng PS, Inoue-Yamauchi A, Hsieh JJ, Cheng EH. BH3-Dependent and Independent Activation of BAX and BAK in Mitochondrial Apoptosis. CURRENT OPINION IN PHYSIOLOGY 2018; 3:71-81. [PMID: 30334018 PMCID: PMC6186458 DOI: 10.1016/j.cophys.2018.03.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mitochondria play key roles in mammalian apoptosis, a highly regulated genetic program of cell suicide. Multiple apoptotic signals culminate in mitochondrial outer membrane permeabilization (MOMP), which not only couples the mitochondria to the activation of caspases but also initiates caspase-independent mitochondrial dysfunction. The BCL-2 family proteins are central regulators of MOMP. Multidomain pro-apoptotic BAX and BAK are essential effectors responsible for MOMP, whereas anti-apoptotic BCL-2, BCL-XL, and MCL-1 preserve mitochondrial integrity. The third BCL-2 subfamily of proteins, BH3-only molecules, promotes apoptosis by either activating BAX and BAK or inactivating BCL-2, BCL-XL, and MCL-1. Through an interconnected hierarchical network of interactions, the BCL-2 family proteins integrate developmental and environmental cues to dictate the survival versus death decision of cells by regulating the integrity of the mitochondrial outer membrane. Over the past 30 years, research on the BCL-2-regulated apoptotic pathway has not only revealed its importance in both normal physiological and disease processes, but has also resulted in the first anti-cancer drug targeting protein-protein interactions.
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Affiliation(s)
- Paul S Jeng
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Akane Inoue-Yamauchi
- Department of Pathology, Tokyo Women's Medical University, Shinjuku-ku, Tokyo 162-8666, Japan
| | - James J Hsieh
- Molecular Oncology, Department of Medicine, Siteman Cancer Center, Washington University, St Louis, MO 63110, USA
| | - Emily H Cheng
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, Cornell University, New York, NY 10065, USA
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44
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Hantusch A, Rehm M, Brunner T. Counting on Death – Quantitative aspects of Bcl‐2 family regulation. FEBS J 2018; 285:4124-4138. [DOI: 10.1111/febs.14516] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/27/2018] [Accepted: 05/21/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Annika Hantusch
- Department of Biology Chair of Biochemical Pharmacology University of Konstanz Germany
- Konstanz Research School Chemical Biology University of Konstanz Germany
| | - Markus Rehm
- Department of Physiology & Medical Physics Royal College of Surgeons in Ireland Dublin 2 Ireland
- Centre for Systems Medicine Royal College of Surgeons in Ireland Dublin 2 Ireland
- Institute of Cell Biology and Immunology University of Stuttgart Germany
- Stuttgart Research Center Systems Biology University of Stuttgart Germany
| | - Thomas Brunner
- Department of Biology Chair of Biochemical Pharmacology University of Konstanz Germany
- Konstanz Research School Chemical Biology University of Konstanz Germany
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45
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Edlich F. BCL-2 proteins and apoptosis: Recent insights and unknowns. Biochem Biophys Res Commun 2018; 500:26-34. [DOI: 10.1016/j.bbrc.2017.06.190] [Citation(s) in RCA: 233] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/30/2017] [Indexed: 01/08/2023]
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46
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New limits of sensitivity of site-directed spin labeling electron paramagnetic resonance for membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:841-853. [DOI: 10.1016/j.bbamem.2017.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 11/27/2017] [Accepted: 12/09/2017] [Indexed: 01/27/2023]
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47
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Uren RT, Iyer S, Kluck RM. Pore formation by dimeric Bak and Bax: an unusual pore? Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630157 DOI: 10.1098/rstb.2016.0218] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Apoptotic cell death via the mitochondrial pathway occurs in all vertebrate cells and requires the formation of pores in the mitochondrial outer membrane. Two Bcl-2 protein family members, Bak and Bax, form these pores during apoptosis, and how they do so has been investigated for the last two decades. Many of the conformation changes that occur during their transition to pore-forming proteins have now been delineated. Notably, biochemical, biophysical and structural studies indicate that symmetric homodimers are the basic unit of pore formation. Each dimer contains an extended hydrophobic surface that lies on the outer membrane, and is anchored at either end by a transmembrane domain. Membrane-remodelling events such as positive membrane curvature have been reported to accompany apoptotic pore formation, suggesting Bak and Bax form lipidic pores rather than proteinaceous pores. However, it remains unclear how symmetric dimers assemble to porate the membrane. Here, we review how clusters of dimers and their lipid-mediated interactions provide a molecular explanation for the heterogeneous assemblies of Bak and Bax observed during apoptosis.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Rachel T Uren
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Sweta Iyer
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Ruth M Kluck
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia .,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
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48
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Membrane insertion of the BAX core, but not latch domain, drives apoptotic pore formation. Sci Rep 2017; 7:16259. [PMID: 29176554 PMCID: PMC5701199 DOI: 10.1038/s41598-017-16384-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 10/31/2017] [Indexed: 12/31/2022] Open
Abstract
Despite intensive research effort, how the paradigmatic proapoptotic protein BAX forms lethal apoptotic pores at the mitochondrial outer membrane (MOM) remains incompletely understood. Here, we used biophysical tools and minimalist model systems to identify the specific regions in BAX driving apoptotic pore formation, and to gain more insight into underlying mechanisms. Fluorescence mapping revealed that fully active BAX adopts a BH3-in-groove dimeric conformation in MOM-like membranes, with BAX α4-α5 helices belonging to its core domain inserting deeper into the membrane lipid bilayer than BAX α6-α8 helices belonging to its latch domain. In our reconstituted systems, antiapoptotic BCLXL formed canonical heterodimeric BH3-in-groove complexes with BAX, and blocked membrane insertion of BAX core α4-α5 helices, but not BAX latch α6-α8 helices. Moreover, poly(ethylene glycol) (PEG) conjugation (PEGylation) at multiple individual sites along the BAX core, but not latch domain, potently inhibited BAX pore-forming activity. Additional combined computational and experimental evidence revealed that the BAX core α5 helix displays a bilayer-destabilizing membrane interaction mode that is absent in BAX latch α6-α8 helices. Based on this collective set of evidence, we propose that membrane insertion of the BAX core, but not latch domain, is critical for BAX apoptotic pore formation.
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49
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Adams JM, Cory S. The BCL-2 arbiters of apoptosis and their growing role as cancer targets. Cell Death Differ 2017; 25:27-36. [PMID: 29099483 PMCID: PMC5729526 DOI: 10.1038/cdd.2017.161] [Citation(s) in RCA: 366] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/30/2017] [Accepted: 08/31/2017] [Indexed: 02/08/2023] Open
Abstract
Impaired apoptosis plays a central role in cancer development and limits the efficacy of conventional cytotoxic therapies. Deepening understanding of how opposing factions of the BCL-2 protein family switch on apoptosis and of their structures has driven development of a new class of cancer drugs that targets various pro-survival members by mimicking their natural inhibitors, the BH3-only proteins. These ‘BH3 mimetic’ drugs seem destined to become powerful new weapons in the arsenal against cancer. Successful clinical trials of venetoclax/ABT-199, a specific inhibitor of BCL-2, have led to its approval for a refractory form of chronic lymphocytic leukaemia and to scores of on-going trials for other malignancies. Furthermore, encouraging preclinical studies of BH3 mimetics that target other BCL-2 pro-survival members, particularly MCL-1, offer promise for cancers resistant to venetoclax. This review sketches the impact of the BCL-2 family on cancer development and therapy, describes how interactions of family members trigger apoptosis and discusses the potential of BH3 mimetic drugs to advance cancer therapy.
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Affiliation(s)
- Jerry M Adams
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Suzanne Cory
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
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50
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Peña‐Blanco A, García‐Sáez AJ. Bax, Bak and beyond — mitochondrial performance in apoptosis. FEBS J 2017; 285:416-431. [DOI: 10.1111/febs.14186] [Citation(s) in RCA: 340] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/12/2017] [Accepted: 07/26/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Aida Peña‐Blanco
- Interfaculty Institute of Biochemistry Tübingen University Germany
| | - Ana J. García‐Sáez
- Interfaculty Institute of Biochemistry Tübingen University Germany
- Max‐Planck Institute for Intelligent Systems Stuttgart Germany
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