1
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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2
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Cheng P, Hou Y, Bian M, Fang X, Liu Y, Rao Y, Cao S, Liu Y, Zhang S, Chen Y, Dong X, Liu Z. Parkin-mediated ubiquitination inhibits BAK apoptotic activity by blocking its canonical hydrophobic groove. Commun Biol 2023; 6:1260. [PMID: 38087033 PMCID: PMC10716173 DOI: 10.1038/s42003-023-05650-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
BAK permeabilizes the mitochondrial outer membrane, causing apoptosis. This apoptotic activity of BAK is stimulated by binding prodeath activators within its canonical hydrophobic groove. Parkin, an E3 ubiquitin (Ub) ligase, can ubiquitinate BAK, which inhibits BAK apoptotic activity. However, the molecular mechanism underlying the inhibition of ubiquitination remains structurally uncharacterized. Here, we utilize truncated and soluble BAK to construct a mimetic of K113-ubiquitinated BAK (disulfide-linked UbG76C ~ BAKK113C) and further present its NMR-derived structure model. The classical L8-I44-H68-V70 hydrophobic patch of the conjugated Ub subunit binds within the canonical hydrophobic groove of BAK. This Ub occludes the binding of prodeath BID activators in the groove and impairs BID-triggered BAK activation and membrane permeabilization. Reduced interaction between Ub and BAK subunits allows BID to activate K113-ubiquitinated BAK. These mechanistic insights suggest a nonsignaling function of Ub in that it directly antagonizes stimuli targeting Ub-modified proteins rather than by recruiting downstream partners for cellular messaging.
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Affiliation(s)
- Peng Cheng
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuzhu Hou
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Mingxing Bian
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xueru Fang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yan Liu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuanfang Rao
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Shuo Cao
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yanjun Liu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Shuai Zhang
- College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yanke Chen
- College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Xu Dong
- Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, China.
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, 430074, China.
| | - Zhu Liu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China.
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3
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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4
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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5
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Moldoveanu T. Apoptotic mitochondrial poration by a growing list of pore-forming BCL-2 family proteins. Bioessays 2023; 45:e2200221. [PMID: 36650950 PMCID: PMC9975053 DOI: 10.1002/bies.202200221] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/31/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023]
Abstract
The pore-forming BCL-2 family proteins are effectors of mitochondrial poration in apoptosis initiation. Two atypical effectors-BOK and truncated BID (tBID)-join the canonical effectors BAK and BAX. Gene knockout revealed developmental phenotypes in the absence the effectors, supporting their roles in vivo. During apoptosis effectors are activated and change shape from dormant monomers to dynamic oligomers that associate with and permeabilize mitochondria. BID is activated by proteolysis, BOK accumulates on inhibition of its degradation by the E3 ligase gp78, while BAK and BAX undergo direct activation by BH3-only initiators, autoactivation, and crossactivation. Except tBID, effector oligomers on the mitochondria appear as arcs and rings in super-resolution microscopy images. The BH3-in-groove dimers of BAK and BAX, the tBID monomers, and uncharacterized BOK species are the putative building blocks of apoptotic pores. Effectors interact with lipids and bilayers but the mechanism of membrane poration remains elusive. I discuss effector-mediated mitochondrial poration.
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Affiliation(s)
- Tudor Moldoveanu
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences,Correspondence:
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6
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Sorokin M, Rabushko E, Rozenberg JM, Mohammad T, Seryakov A, Sekacheva M, Buzdin A. Clinically relevant fusion oncogenes: detection and practical implications. Ther Adv Med Oncol 2022; 14:17588359221144108. [PMID: 36601633 PMCID: PMC9806411 DOI: 10.1177/17588359221144108] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 11/22/2022] [Indexed: 12/28/2022] Open
Abstract
Mechanistically, chimeric genes result from DNA rearrangements and include parts of preexisting normal genes combined at the genomic junction site. Some rearranged genes encode pathological proteins with altered molecular functions. Those which can aberrantly promote carcinogenesis are called fusion oncogenes. Their formation is not a rare event in human cancers, and many of them were documented in numerous study reports and in specific databases. They may have various molecular peculiarities like increased stability of an oncogenic part, self-activation of tyrosine kinase receptor moiety, and altered transcriptional regulation activities. Currently, tens of low molecular mass inhibitors are approved in cancers as the drugs targeting receptor tyrosine kinase (RTK) oncogenic fusion proteins, that is, including ALK, ABL, EGFR, FGFR1-3, NTRK1-3, MET, RET, ROS1 moieties. Therein, the presence of the respective RTK fusion in the cancer genome is the diagnostic biomarker for drug prescription. However, identification of such fusion oncogenes is challenging as the breakpoint may arise in multiple sites within the gene, and the exact fusion partner is generally unknown. There is no gold standard method for RTK fusion detection, and many alternative experimental techniques are employed nowadays to solve this issue. Among them, RNA-seq-based methods offer an advantage of unbiased high-throughput analysis of only transcribed RTK fusion genes, and of simultaneous finding both fusion partners in a single RNA-seq read. Here we focus on current knowledge of biology and clinical aspects of RTK fusion genes, related databases, and laboratory detection methods.
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Affiliation(s)
| | - Elizaveta Rabushko
- Moscow Institute of Physics and Technology,
Dolgoprudny, Moscow Region, Russia,I.M. Sechenov First Moscow State Medical
University, Moscow, Russia
| | | | - Tharaa Mohammad
- Moscow Institute of Physics and Technology,
Dolgoprudny, Moscow Region, Russia
| | | | - Marina Sekacheva
- I.M. Sechenov First Moscow State Medical
University, Moscow, Russia
| | - Anton Buzdin
- Moscow Institute of Physics and Technology,
Dolgoprudny, Moscow Region, Russia,I.M. Sechenov First Moscow State Medical
University, Moscow, Russia,Shemyakin-Ovchinnikov Institute of Bioorganic
Chemistry, Moscow, Russia,PathoBiology Group, European Organization for
Research and Treatment of Cancer (EORTC), Brussels, Belgium
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7
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Vandenabeele P, Bultynck G, Savvides SN. Pore-forming proteins as drivers of membrane permeabilization in cell death pathways. Nat Rev Mol Cell Biol 2022. [PMID: 36543934 DOI: 10.1038/s41580-022-00564-w] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [What about the content of this article? (0)] [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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8
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Athanasopoulou K, Adamopoulos PG, Daneva GN, Scorilas A. Decoding the concealed transcriptional signature of the apoptosis-related BCL2 antagonist/killer 1 (BAK1) gene in human malignancies. Apoptosis 2022; 27:869-882. [DOI: 10.1007/s10495-022-01753-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2022] [Indexed: 11/29/2022]
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9
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Sekar G, Ojoawo A, Moldoveanu T. Protein-protein and protein-lipid interactions of pore-forming BCL-2 family proteins in apoptosis initiation. Biochem Soc Trans 2022:BST20220323. [PMID: 35521828 DOI: 10.1042/BST20220323] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [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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10
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Martens MD, Karch J, Gordon JW. The molecular mosaic of regulated cell death in the cardiovascular system. Biochim Biophys Acta Mol Basis Dis 2021; 1868:166297. [PMID: 34718119 DOI: 10.1016/j.bbadis.2021.166297] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 10/07/2021] [Accepted: 10/22/2021] [Indexed: 12/11/2022]
Abstract
Cell death is now understood to be a highly regulated process that contributes to normal development and tissue homeostasis, alongside its role in the etiology of various pathological conditions. Through detailed molecular analysis, we have come to know that all cells do not always die in the same way, and that there are at least 7 processes involved, including: apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, and autophagy-mediated cell death. These processes act as pieces in the mosaic of cardiomyocyte cell death, which come together depending on context and stimulus. This review details each individual process, as well as highlights how they come together to produce various cardiac pathologies. By knowing how the pieces go together we can aim towards the development of efficacious therapeutics, which will enable us to prevent cardiomyocyte loss in the face of stress, both reducing mortality and improving quality of life.
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Affiliation(s)
- Matthew D Martens
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Science, University of Manitoba, Winnipeg, Manitoba, Canada; The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Canada
| | - Jason Karch
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, United States
| | - Joseph W Gordon
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Science, University of Manitoba, Winnipeg, Manitoba, Canada; College of Nursing, Rady Faculty of Health Science, University of Manitoba, Winnipeg, Manitoba, Canada; The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Canada.
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11
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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12
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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13
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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14
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He XL, He YM, Zhang D, Li HS, Zhang Q, Yuan SS, Zhang Z, Wang YY, Liu CH, Fan CH, Li YH, Zheng M, Yang HJ, Zhou P. Efficacy and Mechanism of a Chinese Classic Prescription of Yueju in Treating Nonalcoholic Steatohepatitis and Protecting Hepatocytes from Apoptosis. Evid Based Complement Alternat Med 2020; 2020:8888040. [PMID: 33178326 PMCID: PMC7644301 DOI: 10.1155/2020/8888040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/03/2020] [Accepted: 10/11/2020] [Indexed: 02/06/2023]
Abstract
Yueju, a famous classic Chinese prescription, has been extensively used in treating depression syndromes for hundreds of years. Recent studies have reported that Yueju showed good effects in treating metabolic diseases, such as obesity and hyperlipidemia. Nonalcoholic steatohepatitis (NASH), which leads to cirrhosis and severe cardiovascular diseases, is closely linked to obesity and abnormal lipid metabolism. In this study, Yueju could decrease the levels of alanine aminotransferase, aspartate transaminase, triglyceride, cholesterol, and low-density lipoprotein-C but increase the high-density lipoprotein-C in the serum of the NASH rat model induced by high-fat and high-cholesterol diet. Yueju could alleviate hepatosteatosis by increasing the phosphorylation of acetyl-CoA carboxylase and inhibiting the expression of fatty acid synthase and stearoyl-CoA desaturase 1. Yueju downregulated the expression of α-smooth muscle actin and collagen type 1A1, ameliorating the liver fibrilization. Yueju could also protect the hepatocytes from apoptosis by upregulating antiapoptosis protein Bcl-2 and X-linked inhibitor of apoptosis protein and downregulating apoptotic proteins Bax and cleaved poly ADP-ribose polymerase. Thus, Yueju could improve liver function, regulate lipid metabolism, alleviate hepatosteatosis and fibrosis, and protect hepatocytes from apoptosis against NASH. Yueju may be used as an alternative effective medicine for NASH treatment.
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Affiliation(s)
- Xiao-Li He
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Yan-Ming He
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Dan Zhang
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Hong-Shan Li
- Department of Hepatology, Ningbo Huamei Hospital, University of Chinese Academy of Sciences, 41 Xibei Road, Ningbo 315010, China
| | - Qiang Zhang
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Sha-Sha Yuan
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Zeng Zhang
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Yan-Yan Wang
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Cheng-Hao Liu
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Chao-Hua Fan
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Yun-Hao Li
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Min Zheng
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Hong-Jie Yang
- Department of Endocrinology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China
| | - Ping Zhou
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, 220 Handan Road, Shanghai 200433, China
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15
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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] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 07/31/2020] [Indexed: 12/27/2022]
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16
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Abstract
Bax and Bak, two functionally similar, pro-apoptotic proteins of the Bcl-2 family, are known as the gateway to apoptosis because of their requisite roles as effectors of mitochondrial outer membrane permeabilization (MOMP), a major step during mitochondria-dependent apoptosis. The mechanism of how cells turn Bax/Bak from inert molecules into fully active and lethal effectors had long been the focal point of a major debate centered around two competing, but not mutually exclusive, models: direct activation and indirect activation. After intensive research efforts for over two decades, it is now widely accepted that to initiate apoptosis, some of the BH3-only proteins, a subclass of the Bcl-2 family, directly engage Bax/Bak to trigger their conformational transformation and activation. However, a series of recent discoveries, using previously unavailable CRISPR-engineered cell systems, challenge the basic premise that undergirds the consensus and provide evidence for a novel and surprisingly simple model of Bax/Bak activation: the membrane (lipids)-mediated spontaneous model. This review will discuss the evidence, rationale, significance, and implications of this new model.
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Affiliation(s)
- Xu Luo
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Alaska Medical Center, Omaha, ME, 68198-7696, USA.,Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198-6805, USA
| | - Katelyn L O'Neill
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Alaska Medical Center, Omaha, ME, 68198-7696, USA
| | - Kai Huang
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Alaska Medical Center, Omaha, ME, 68198-7696, USA.,Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198-6805, USA
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17
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Yi G, Li H, Li Y, Zhao F, Ying Z, Liu M, Zhang J, Liu X. The protective effect of soybean protein-derived peptides on apoptosis via the activation of PI3K-AKT and inhibition on apoptosis pathway. Food Sci Nutr 2020; 8:4591-4600. [PMID: 32884739 PMCID: PMC7455986 DOI: 10.1002/fsn3.1776] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 06/10/2020] [Accepted: 06/11/2020] [Indexed: 12/11/2022] Open
Abstract
Soybean protein-derived peptides (SBP) are a rich source of various bioactive peptides with multiple health benefits. However, the prospective effects of SBP on human cells are still unclear. Therefore, this article investigated the effects of small molecular weight SBP on MG132-induced apoptosis in RAW264.7 cells. SBP inhibited MG132-induced apoptosis of RAW264.7 cells in a dose-dependent manner by flow cytometry. To further study its molecular mechanisms, Western blot analysis demonstrated that SBP could activate the PI3K-AKT pathway by increasing the phosphorylation of PI3K and AKT and inhibiting apoptosis pathway by downregulating the expressions of pro-apoptotic proteins of Bim, Bax, Fas, and Fasl and promoting the expressions of anti-apoptotic proteins of Bcl-xL and Bcl-2. These results indicated the protective effect of SBP on MG132-induced apoptosis in RAW264.7 cells.
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Affiliation(s)
- Guofu Yi
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
| | - He Li
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
| | - You Li
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
| | - Fen Zhao
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
| | - Zhiwei Ying
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
| | - Menglan Liu
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
| | - Jian Zhang
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
| | - Xinqi Liu
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Engineering and Technology Research Center of Food AdditivesBeijing Technology and Business University (BTBU)BeijingChina
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18
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Iyer S, Uren RT, Dengler MA, Shi MX, Uno E, Adams JM, Dewson G, Kluck RM. Robust autoactivation for apoptosis by BAK but not BAX highlights BAK as an important therapeutic target. Cell Death Dis 2020; 11:268. [PMID: 32327636 DOI: 10.1038/s41419-020-2463-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [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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19
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Dudko HV, Urban VA, Davidovskii AI, Veresov VG. Structure-based modeling of turnover of Bcl-2 family proteins bound to voltage-dependent anion channel 2 (VDAC2): Implications for the mechanisms of proapoptotic activation of Bak and Bax in vivo. Comput Biol Chem 2020; 85:107203. [DOI: 10.1016/j.compbiolchem.2020.107203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/31/2019] [Accepted: 01/13/2020] [Indexed: 12/15/2022]
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20
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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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21
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van Delft MF, Chappaz S, Khakham Y, Bui CT, Debrincat MA, Lowes KN, Brouwer JM, Grohmann C, Sharp PP, Dagley LF, Li L, McArthur K, Luo MX, Chin HS, Fairlie WD, Lee EF, Segal D, Duflocq S, Lessene R, Bernard S, Peilleron L, Nguyen T, Miles C, Wan SS, Lane RM, Wardak A, Lackovic K, Colman PM, Sandow JJ, Webb AI, Czabotar PE, Dewson G, Watson KG, Huang DCS, Lessene G, Kile BT. A small molecule interacts with VDAC2 to block mouse BAK-driven apoptosis. Nat Chem Biol 2019; 15:1057-66. [PMID: 31591564 DOI: 10.1038/s41589-019-0365-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/15/2019] [Indexed: 02/07/2023]
Abstract
Activating the intrinsic apoptosis pathway with small molecules is now a clinically validated approach to cancer therapy. In contrast, blocking apoptosis to prevent the death of healthy cells in disease settings has not been achieved. Caspases have been favored, but they act too late in apoptosis to provide long-term protection. The critical step in committing a cell to death is activation of BAK or BAX, pro-death BCL-2 proteins mediating mitochondrial damage. Apoptosis cannot proceed in their absence. Here we show that WEHI-9625, a novel tricyclic sulfone small molecule, binds to VDAC2 and promotes its ability to inhibit apoptosis driven by mouse BAK. In contrast to caspase inhibitors, WEHI-9625 blocks apoptosis before mitochondrial damage, preserving cellular function and long-term clonogenic potential. Our findings expand on the key role of VDAC2 in regulating apoptosis and demonstrate that blocking apoptosis at an early stage is both advantageous and pharmacologically tractable.
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22
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Abstract
The proteins of the BCL2 family are key players in multiple cellular processes, chief amongst them being the regulation of mitochondrial integrity and apoptotic cell death. These proteins establish an intricate interaction network that expands both the cytosol and the surface of organelles to dictate the cell fate. The complexity and unpredictability of the BCL2 interactome resides in the large number of family members and of interaction surfaces, as well as on their different behaviours in solution and in the membrane. Although our current structural knowledge of the BCL2 proteins has been proven therapeutically relevant, the precise structure of membrane-bound complexes and the regulatory effect that membrane lipids exert over these proteins remain key questions in the field. Here, we discuss the complexity of BCL2 interactome, the new insights, and the black matter in the field.
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23
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Razaghi A, Heimann K, Schaeffer PM, Gibson SB. Negative regulators of cell death pathways in cancer: perspective on biomarkers and targeted therapies. Apoptosis 2018; 23:93-112. [PMID: 29322476 DOI: 10.1007/s10495-018-1440-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cancer is a primary cause of human fatality and conventional cancer therapies, e.g., chemotherapy, are often associated with adverse side-effects, tumor drug-resistance, and recurrence. Molecularly targeted therapy, composed of small-molecule inhibitors and immunotherapy (e.g., monoclonal antibody and cancer vaccines), is a less harmful alternative being more effective against cancer cells whilst preserving healthy tissues. Drug-resistance, however, caused by negative regulation of cell death signaling pathways, is still a challenge. Circumvention of negative regulators of cell death pathways or development of predictive and response biomarkers is, therefore, quintessential. This review critically discusses the current state of knowledge on targeting negative regulators of cell death signaling pathways including apoptosis, ferroptosis, necroptosis, autophagy, and anoikis and evaluates the recent advances in clinical and preclinical research on biomarkers of negative regulators. It aims to provide a comprehensive platform for designing efficacious polytherapies including novel agents for restoring cell death signaling pathways or targeting alternative resistance pathways to improve the chances for antitumor responses. Overall, it is concluded that nonapoptotic cell death pathways are a potential research arena for drug discovery, development of novel biomarkers and targeted therapies.
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24
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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25
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Bernardini JP, Brouwer JM, Tan IK, Sandow JJ, Huang S, Stafford CA, Bankovacki A, Riffkin CD, Wardak AZ, Czabotar PE, Lazarou M, Dewson G. Parkin inhibits BAK and BAX apoptotic function by distinct mechanisms during mitophagy. EMBO J 2018; 38:embj.201899916. [PMID: 30573668 DOI: 10.15252/embj.201899916] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 11/08/2018] [Accepted: 11/13/2018] [Indexed: 12/26/2022] Open
Abstract
The E3 ubiquitin ligase Parkin is a key effector of the removal of damaged mitochondria by mitophagy. Parkin determines cell fate in response to mitochondrial damage, with its loss promoting early onset Parkinson's disease and potentially also cancer progression. Controlling a cell's apoptotic response is essential to co-ordinate the removal of damaged mitochondria. We report that following mitochondrial damage-induced mitophagy, Parkin directly ubiquitinates the apoptotic effector protein BAK at a conserved lysine in its hydrophobic groove, a region that is crucial for BAK activation by BH3-only proteins and its homo-dimerisation during apoptosis. Ubiquitination inhibited BAK activity by impairing its activation and the formation of lethal BAK oligomers. Parkin also suppresses BAX-mediated apoptosis, but in the absence of BAX ubiquitination suggesting an indirect mechanism. In addition, we find that BAK-dependent mitochondrial outer membrane permeabilisation during apoptosis promotes PINK1-dependent Parkin activation. Hence, we propose that Parkin directly inhibits BAK to suppress errant apoptosis, thereby allowing the effective clearance of damaged mitochondria, but also promotes clearance of apoptotic mitochondria to limit their potential pro-inflammatory effect.
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Affiliation(s)
- Jonathan P Bernardini
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia.,Department of Medical Biology, University of Melbourne, Parkville, Melbourne, Vic., Australia
| | - Jason M Brouwer
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia.,Department of Medical Biology, University of Melbourne, Parkville, Melbourne, Vic., Australia
| | - Iris Kl Tan
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia
| | - Jarrod J Sandow
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia.,Department of Medical Biology, University of Melbourne, Parkville, Melbourne, Vic., Australia
| | - Shuai Huang
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia.,Department of Medical Biology, University of Melbourne, Parkville, Melbourne, Vic., Australia
| | - Che A Stafford
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia.,Department of Medical Biology, University of Melbourne, Parkville, Melbourne, Vic., Australia
| | - Aleksandra Bankovacki
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia
| | - Christopher D Riffkin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia
| | - Ahmad Z Wardak
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia.,Department of Medical Biology, University of Melbourne, Parkville, Melbourne, Vic., Australia
| | - Michael Lazarou
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute Monash University, Clayton, Melbourne, Vic., Australia
| | - Grant Dewson
- Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Vic., Australia .,Department of Medical Biology, University of Melbourne, Parkville, Melbourne, Vic., Australia
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26
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Bleicken S, Assafa TE, Stegmueller C, Wittig A, Garcia-Saez AJ, Bordignon E. Topology of active, membrane-embedded Bax in the context of a toroidal pore. Cell Death Differ 2018; 25:1717-31. [PMID: 30185826 DOI: 10.1038/s41418-018-0184-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [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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27
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Robin AY, Iyer S, Birkinshaw RW, Sandow J, Wardak A, Luo CS, Shi M, Webb AI, Czabotar PE, Kluck RM, Colman PM. Ensemble Properties of Bax Determine Its Function. Structure 2018; 26:1346-1359.e5. [PMID: 30122452 DOI: 10.1016/j.str.2018.07.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 05/31/2018] [Accepted: 07/21/2018] [Indexed: 11/20/2022]
Abstract
BAX and BAK are essential mediators of intrinsic apoptosis that permeabilize the mitochondrial outer membrane. BAX activation requires its translocation from cytosol to mitochondria where conformational changes cause its oligomerization. To better understand the critical step of translocation, we examined its blockade by mutation near the C terminus (P168G) or by antibody binding near the N terminus. Similarities in the crystal structures of wild-type and BAX P168G but significant other differences suggest that cytosolic BAX exists as an ensemble of conformers, and that the distribution of conformers within the ensemble determines the different functions of wild-type and mutant proteins. We also describe the structure of BAX in complex with an antibody, 3C10, that inhibits cytosolic BAX by limiting exposure of the membrane-associating helix α9, as does the P168G mutation. Our data for both means of BAX inhibition argue for an allosteric model of BAX regulation that derives from properties of the ensemble of conformers.
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28
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Bordignon E, Bleicken S. New limits of sensitivity of site-directed spin labeling electron paramagnetic resonance for membrane proteins. Biochimica et Biophysica Acta (BBA) - Biomembranes 2018; 1860:841-53. [DOI: 10.1016/j.bbamem.2017.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [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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29
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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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30
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Lindqvist LM, Frank D, McArthur K, Dite TA, Lazarou M, Oakhill JS, Kile BT, Vaux DL. Autophagy induced during apoptosis degrades mitochondria and inhibits type I interferon secretion. Cell Death Differ 2018; 25:784-96. [PMID: 29229994 DOI: 10.1038/s41418-017-0017-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 10/10/2017] [Accepted: 10/18/2017] [Indexed: 02/08/2023] Open
Abstract
Cells undergoing Bax/Bak-mediated apoptosis exhibit signs of autophagy, but how it is activated and its significance is unknown. By directly activating Bax/Bak with BH3-only proteins or BH3 mimetic compounds, we demonstrate that mitochondrial damage correlated with a rapid increase in intracellular [AMP]/[ATP], phosphorylation of 5' AMP-activated protein kinase (AMPK), and activation of unc-51 like autophagy activating kinase 1 (ULK1). Consequently, autophagic flux was triggered early in the apoptotic pathway, as activation of the apoptosome and caspases were not necessary for its induction. Bax/Bak-triggered autophagy resulted in the clearance of damaged mitochondria in an ATG5/7-dependent manner that did not require Parkin. Importantly, Bax/Bak-mediated autophagy inhibited the secretion of the pro-inflammatory cytokine interferon-β (IFN-β) produced in response to mitochondrial damage, but not another cytokine interleukin-6 (IL-6). These findings show that Bax/Bak stimulated autophagy is essential for ensuring immunological silence during apoptosis.
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31
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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: 362] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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32
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Kvansakul M, Caria S, Hinds MG. The Bcl-2 Family in Host-Virus Interactions. Viruses 2017; 9:E290. [PMID: 28984827 DOI: 10.3390/v9100290] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/01/2017] [Accepted: 10/03/2017] [Indexed: 12/13/2022] Open
Abstract
Members of the B cell lymphoma-2 (Bcl-2) family are pivotal arbiters of mitochondrially mediated apoptosis, a process of fundamental importance during tissue development, homeostasis, and disease. At the structural and mechanistic level, the mammalian members of the Bcl-2 family are increasingly well understood, with their interplay ultimately deciding the fate of a cell. Dysregulation of Bcl-2-mediated apoptosis underlies a plethora of diseases, and numerous viruses have acquired homologs of Bcl-2 to subvert host cell apoptosis and autophagy to prevent premature death of an infected cell. Here we review the structural biology, interactions, and mechanisms of action of virus-encoded Bcl-2 proteins, and how they impact on host-virus interactions to ultimately enable successful establishment and propagation of viral infections.
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33
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Li MX, Tan IKL, Ma SB, Hockings C, Kratina T, Dengler MA, Alsop AE, Kluck RM, Dewson G. BAK α6 permits activation by BH3-only proteins and homooligomerization via the canonical hydrophobic groove. Proc Natl Acad Sci U S A 2017; 114:7629-34. [PMID: 28673969 DOI: 10.1073/pnas.1702453114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BAK and BAX are the essential effectors of apoptosis because without them a cell is resistant to most apoptotic stimuli. BAK and BAX undergo conformation changes to homooligomerize then permeabilize the mitochondrial outer membrane during apoptosis. How BCL-2 homology 3 (BH3)-only proteins bind to activate BAK and BAX is unclear. We report that BH3-only proteins bind inactive full-length BAK at mitochondria and then dissociate following exposure of the BAK BH3 and BH4 domains before BAK homodimerization. Using a functional obstructive labeling approach, we show that activation of BAK involves important interactions of BH3-only proteins with both the canonical hydrophobic binding groove (α2-5) and α6 at the rear of BAK, with interaction at α6 promoting an open groove to receive a BH3-only protein. Once activated, how BAK homodimers multimerize to form the putative apoptotic pore is unknown. Obstructive labeling of BAK beyond the BH3 domain and hydrophobic groove did not inhibit multimerization and mitochondrial damage, indicating that critical protein-protein interfaces in BAK self-association are limited to the α2-5 homodimerization domain.
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34
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Abstract
How cytochrome C is released from the mitochondria to the cytosol via Bax oligomeric pores, a process which is required for apoptosis, is still a mystery. Based on experimentally measured residue-residue distances, we recently solved the first atomic model for Bax oligomeric pores at the membranes using computational approaches. Here, we investigate the mechanism at the microsecond time- and nanometer space- scale using MD simulations. Our free energy landscape depicts a low barrier for the permeation of cytochrome C into the Bax C-terminal mouth, with the pathway proceeding to the inner cavity and exiting via the N-terminal mouth. Release is guided by organized charged/hydrophilic surfaces. The hydrophilicity and negative charge of the pore surface gradually increase along the release pathway from the pore entry to the exit opening. Rather than inert passing of the cytochrome C through a rigid pore, the flexible pore may selectively aid the cytochrome C passage. Once the Bax pore is formed in the membrane, with a low energy barrier, the release of cytochrome C may be readily achieved through energy fluctuations. Collectively, our work provides mechanistic insight in atomic detail into the release of cytochrome C through Bax oligomeric pores.
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Affiliation(s)
- Mingzhen Zhang
- Department of Chemical & Biomolecular Engineering, the University of Akron, Akron, Ohio, 44325, USA
| | - Jie Zheng
- Department of Chemical & Biomolecular Engineering, the University of Akron, Akron, Ohio, 44325, USA
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, 21702, USA
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, 21702, USA.
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35
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Simonyan L, Légiot A, Lascu I, Durand G, Giraud MF, Gonzalez C, Manon S. The substitution of Proline 168 favors Bax oligomerization and stimulates its interaction with LUVs and mitochondria. Biochimica et Biophysica Acta (BBA) - Biomembranes 2017; 1859:1144-1155. [DOI: 10.1016/j.bbamem.2017.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 02/28/2017] [Accepted: 03/14/2017] [Indexed: 12/23/2022]
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36
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Aouacheria A, Baghdiguian S, Lamb HM, Huska JD, Pineda FJ, Hardwick JM. Connecting mitochondrial dynamics and life-or-death events via Bcl-2 family proteins. Neurochem Int 2017; 109:141-161. [PMID: 28461171 DOI: 10.1016/j.neuint.2017.04.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 04/17/2017] [Indexed: 12/12/2022]
Abstract
The morphology of a population of mitochondria is the result of several interacting dynamical phenomena, including fission, fusion, movement, elimination and biogenesis. Each of these phenomena is controlled by underlying molecular machinery, and when defective can cause disease. New understanding of the relationships between form and function of mitochondria in health and disease is beginning to be unraveled on several fronts. Studies in mammals and model organisms have revealed that mitochondrial morphology, dynamics and function appear to be subject to regulation by the same proteins that regulate apoptotic cell death. One protein family that influences mitochondrial dynamics in both healthy and dying cells is the Bcl-2 protein family. Connecting mitochondrial dynamics with life-death pathway forks may arise from the intersection of Bcl-2 family proteins with the proteins and lipids that determine mitochondrial shape and function. Bcl-2 family proteins also have multifaceted influences on cells and mitochondria, including calcium handling, autophagy and energetics, as well as the subcellular localization of mitochondrial organelles to neuronal synapses. The remarkable range of physical or functional interactions by Bcl-2 family proteins is challenging to assimilate into a cohesive understanding. Most of their effects may be distinct from their direct roles in apoptotic cell death and are particularly apparent in the nervous system. Dual roles in mitochondrial dynamics and cell death extend beyond BCL-2 family proteins. In this review, we discuss many processes that govern mitochondrial structure and function in health and disease, and how Bcl-2 family proteins integrate into some of these processes.
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Affiliation(s)
- Abdel Aouacheria
- Institute of Evolutionary Sciences of Montpellier (ISEM), CNRS UMR 5554, University of Montpellier, Place Eugène Bataillon, 34095 Montpellier, France
| | - Stephen Baghdiguian
- Institute of Evolutionary Sciences of Montpellier (ISEM), CNRS UMR 5554, University of Montpellier, Place Eugène Bataillon, 34095 Montpellier, France
| | - Heather M Lamb
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - Jason D Huska
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - Fernando J Pineda
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA; Department of Biostatistics, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - J Marie Hardwick
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA.
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37
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Birkinshaw RW, Czabotar PE. The BCL-2 family of proteins and mitochondrial outer membrane permeabilisation. Semin Cell Dev Biol 2017; 72:152-162. [PMID: 28396106 DOI: 10.1016/j.semcdb.2017.04.001] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 03/03/2017] [Accepted: 04/06/2017] [Indexed: 01/24/2023]
Abstract
Apoptosis is a form of programmed cell death critical for the development and homeostasis of multicellular organisms. A key event within the mitochondrial pathway to apoptosis is the permeabilisation of the mitochondrial outer membrane (MOM), a point of no return in apoptotic progression. This event is governed by a complex interplay of interactions between BCL-2 family members. Here we discuss the roles of opposing factions within the family. We focus on the structural details of these interactions, how they promote or prevent apoptosis and recent developments towards understanding the conformational changes of BAK and BAX that lead to MOM permeabilisation. These interactions and structural insights are of particular interest for drug discovery, as highlighted by the development of therapeutics that target pro-survival family members and restore apoptosis in cancer cells.
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Affiliation(s)
- Richard W Birkinshaw
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia.
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38
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Niu X, Brahmbhatt H, Mergenthaler P, Zhang Z, Sang J, Daude M, Ehlert FGR, Diederich WE, Wong E, Zhu W, Pogmore J, Nandy JP, Satyanarayana M, Jimmidi RK, Arya P, Leber B, Lin J, Culmsee C, Yi J, Andrews DW. A Small-Molecule Inhibitor of Bax and Bak Oligomerization Prevents Genotoxic Cell Death and Promotes Neuroprotection. Cell Chem Biol 2017; 24:493-506.e5. [PMID: 28392146 DOI: 10.1016/j.chembiol.2017.03.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/29/2016] [Accepted: 03/13/2017] [Indexed: 11/24/2022]
Abstract
Aberrant apoptosis can lead to acute or chronic degenerative diseases. Mitochondrial outer membrane permeabilization (MOMP) triggered by the oligomerization of the Bcl-2 family proteins Bax/Bak is an irreversible step leading to execution of apoptosis. Here, we describe the discovery of small-molecule inhibitors of Bax/Bak oligomerization that prevent MOMP. We demonstrate that these molecules disrupt multiple, but not all, interactions between Bax dimer interfaces thereby interfering with the formation of higher-order oligomers in the MOM, but not recruitment of Bax to the MOM. Small-molecule inhibition of Bax/Bak oligomerization allowed cells to evade apoptotic stimuli and rescued neurons from death after excitotoxicity, demonstrating that oligomerization of Bax is essential for MOMP. Our discovery of small-molecule Bax/Bak inhibitors provides novel tools for the investigation of the mechanisms leading to MOMP and will ultimately facilitate development of compounds inhibiting Bax/Bak in acute and chronic degenerative diseases.
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39
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Uren RT, O'Hely M, Iyer S, Bartolo R, Shi MX, Brouwer JM, Alsop AE, Dewson G, Kluck RM. Disordered clusters of Bak dimers rupture mitochondria during apoptosis. eLife 2017; 6. [PMID: 28182867 PMCID: PMC5302884 DOI: 10.7554/elife.19944] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 01/08/2017] [Indexed: 11/13/2022] Open
Abstract
During apoptosis, Bak and Bax undergo major conformational change and form symmetric dimers that coalesce to perforate the mitochondrial outer membrane via an unknown mechanism. We have employed cysteine labelling and linkage analysis to the full length of Bak in mitochondria. This comprehensive survey showed that in each Bak dimer the N-termini are fully solvent-exposed and mobile, the core is highly structured, and the C-termini are flexible but restrained by their contact with the membrane. Dimer-dimer interactions were more labile than the BH3:groove interaction within dimers, suggesting there is no extensive protein interface between dimers. In addition, linkage in the mobile Bak N-terminus (V61C) specifically quantified association between dimers, allowing mathematical simulations of dimer arrangement. Together, our data show that Bak dimers form disordered clusters to generate lipidic pores. These findings provide a molecular explanation for the observed structural heterogeneity of the apoptotic pore. DOI:http://dx.doi.org/10.7554/eLife.19944.001 A healthy organism must carefully remove unwanted, diseased or damaged cells. These unwanted cells can bring about their own death in a controlled process known as apoptosis. Maintaining an appropriate level of apoptosis is crucial to good health: excessive cell death can contribute to neurodegenerative disorders, whereas too little can result in cancer. All cells contain powerhouses called mitochondria, which produce energy. Mitochondria are the scene of a critical ‘point of no return’ in apoptosis. When a cell receives a death signal, a ‘killer’ protein known as Bak punches holes (or pores) in the membrane of the mitochondria. These pores allow toxic molecules to leak out from the mitochondria into the interior of the cell, where they trigger a series of events that dismantles the cell from the inside out. To create the pores, Bak undergoes extensive shape changes that allow the proteins to form dimers that then cluster and perforate the membrane. To investigate how Bak clusters assemble on the mitochondrial membrane, Uren et al. used cultured cells and biochemical techniques to show where the Bak dimers contacted each other before and after the pore formed; these findings were complemented with mathematical modelling. The results show that during apoptosis, Bak dimers contact each other at several different places (rather than at one or two places) to assemble into disorderly, ever-changing clusters. Based on these observations, Uren et al. suggest that the enlarging clusters stress the membrane and cause pores to form. The next step is to investigate whether physical forces that act within the mitochondrial membrane could drive the clustering of Bak proteins. This knowledge could ultimately enable us to learn how to manipulate apoptosis in cells, potentially as part of treatments for the diseases in which this cell death process occurs inappropriately. DOI:http://dx.doi.org/10.7554/eLife.19944.002
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Affiliation(s)
- Rachel T Uren
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Martin O'Hely
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Sweta Iyer
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Ray Bartolo
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Melissa X Shi
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Jason M Brouwer
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Amber E Alsop
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Grant Dewson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Ruth M Kluck
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
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40
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Andreu-Fernández V, Sancho M, Genovés A, Lucendo E, Todt F, Lauterwasser J, Funk K, Jahreis G, Pérez-Payá E, Mingarro I, Edlich F, Orzáez M. Bax transmembrane domain interacts with prosurvival Bcl-2 proteins in biological membranes. Proc Natl Acad Sci U S A 2017; 114:310-5. [PMID: 28028215 DOI: 10.1073/pnas.1612322114] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Bcl-2 (B-cell lymphoma 2) protein Bax (Bcl-2 associated X, apoptosis regulator) can commit cells to apoptosis via outer mitochondrial membrane permeabilization. Bax activity is controlled in healthy cells by prosurvival Bcl-2 proteins. C-terminal Bax transmembrane domain interactions were implicated recently in Bax pore formation. Here, we show that the isolated transmembrane domains of Bax, Bcl-xL (B-cell lymphoma-extra large), and Bcl-2 can mediate interactions between Bax and prosurvival proteins inside the membrane in the absence of apoptotic stimuli. Bcl-2 protein transmembrane domains specifically homooligomerize and heterooligomerize in bacterial and mitochondrial membranes. Their interactions participate in the regulation of Bcl-2 proteins, thus modulating apoptotic activity. Our results suggest that interactions between the transmembrane domains of Bax and antiapoptotic Bcl-2 proteins represent a previously unappreciated level of apoptosis regulation.
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41
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Mandal T, Shin S, Aluvila S, Chen HC, Grieve C, Choe JY, Cheng EH, Hustedt EJ, Oh KJ. Assembly of Bak homodimers into higher order homooligomers in the mitochondrial apoptotic pore. Sci Rep 2016; 6:30763. [PMID: 27488021 PMCID: PMC4973285 DOI: 10.1038/srep30763] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/08/2016] [Indexed: 11/09/2022] Open
Abstract
In mitochondrial apoptosis, Bak is activated by death signals to form pores of unknown structure on the mitochondrial outer membrane via homooligomerization. Cytochrome c and other apoptotic factors are released from the intermembrane space through these pores, initiating downstream apoptosis events. Using chemical crosslinking and double electron electron resonance (DEER)-derived distance measurements between specific structural elements in Bak, here we clarify how the Bak pore is assembled. We propose that previously described BH3-in-groove homodimers (BGH) are juxtaposed via the 'α3/α5' interface, in which the C-termini of helices α3 and α5 are in close proximity between two neighboring Bak homodimers. This interface is observed concomitantly with the well-known 'α6:α6' interface. We also mapped the contacts between Bak homodimers and the lipid bilayer based on EPR spectroscopy topology studies. Our results suggest a model for the lipidic Bak pore, whereby the mitochondrial targeting C-terminal helix does not change topology to accommodate the lining of the pore lumen by BGH.
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Affiliation(s)
- Tirtha Mandal
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, USA
| | - Seungjin Shin
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, USA
| | - Sreevidya Aluvila
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, USA
| | - Hui-Chen Chen
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Carter Grieve
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, USA
| | - Jun-Yong Choe
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, USA
| | - Emily H Cheng
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Eric J Hustedt
- Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Kyoung Joon Oh
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, USA
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42
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Falah M, Najafi M, Houshmand M, Farhadi M. Expression levels of the BAK1 and BCL2 genes highlight the role of apoptosis in age-related hearing impairment. Clin Interv Aging 2016; 11:1003-8. [PMID: 27555755 PMCID: PMC4968686 DOI: 10.2147/cia.s109110] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Age-related hearing impairment (ARHI) is a progressive and a common sensory disorder in the elderly and will become an increasingly important clinical problem given the growing elderly population. Apoptosis of cochlear cells is an important factor in animal models of ARHI. As these cells cannot regenerate, their loss leads to irreversible hearing impairment. Identification of molecular mechanisms can facilitate disease prevention and effective treatment. In this study, we compared the expression of the genes BAK1 and BCL2 as two arms of the intrinsic apoptosis pathway between patients with ARHI and healthy subjects. ARHI and healthy subjects were selected after an ear nose throat examination, otoscopic investigation, and pure tone audiometry. RNA was extracted from peripheral blood samples, and relative gene expression levels were measured using quantitative real-time polymerase chain reaction. BAK1 and the BAK1/BCL2 ratio were statistically significantly upregulated in the ARHI subjects. The BAK1/BCL2 ratio was positively correlated with the results of the audiometric tests. Our results indicate that BAK-mediated apoptosis may be a core mechanism in the progression of ARHI in humans, similar to finding in animal models. Moreover, the gene expression changes in peripheral blood samples could be used as a rapid and simple biomarker for early detection of ARHI.
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Affiliation(s)
- Masoumeh Falah
- ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Biochemistry Department, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Najafi
- Cellular and Molecular Research Center, Biochemistry Department, Iran University of Medical Sciences, Tehran, Iran
| | - Massoud Houshmand
- Department of Medical Genetics, National Institute for Genetic Engineering and Biotechnology, Tehran, Iran
| | - Mohammad Farhadi
- ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences, Tehran, Iran
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Liao C, Zhang Z, Kale J, Andrews DW, Lin J, Li J. Conformational Heterogeneity of Bax Helix 9 Dimer for Apoptotic Pore Formation. Sci Rep 2016; 6:29502. [PMID: 27381287 DOI: 10.1038/srep29502] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 06/20/2016] [Indexed: 11/27/2022] Open
Abstract
Helix α9 of Bax protein can dimerize in the mitochondrial outer membrane (MOM) and lead to apoptotic pores. However, it remains unclear how different conformations of the dimer contribute to the pore formation on the molecular level. Thus we have investigated various conformational states of the α9 dimer in a MOM model — using computer simulations supplemented with site-specific mutagenesis and crosslinking of the α9 helices. Our data not only confirmed the critical membrane environment for the α9 stability and dimerization, but also revealed the distinct lipid-binding preference of the dimer in different conformational states. In our proposed pathway, a crucial iso-parallel dimer that mediates the conformational transition was discovered computationally and validated experimentally. The corroborating evidence from simulations and experiments suggests that, helix α9 assists Bax activation via the dimer heterogeneity and interactions with specific MOM lipids, which eventually facilitate proteolipidic pore formation in apoptosis regulation.
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44
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Luna-Vargas MP, Chipuk JE. The deadly landscape of pro-apoptotic BCL-2 proteins in the outer mitochondrial membrane. FEBS J 2016; 283:2676-89. [PMID: 26662859 PMCID: PMC4907887 DOI: 10.1111/febs.13624] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 11/11/2015] [Accepted: 12/08/2015] [Indexed: 01/06/2023]
Abstract
Apoptosis is a biological process that removes damaged, excess or infected cells through a genetically controlled mechanism. This process plays a crucial role in organismal development, immunity and tissue homeostasis, and alterations in apoptosis contribute to human diseases including cancer and auto-immunity. In the past two decades, significant efforts have focused on understanding the function of the BCL-2 proteins, a complex family of pro-survival and pro-apoptotic α-helical proteins that directly control the mitochondrial pathway of apoptosis. Diverse structural investigations of the BCL-2 family members have broadened our mechanistic understanding of their individual functions. However, an often over-looked aspect of the mitochondrial pathway of apoptosis is how the BCL-2 family specifically interacts with and targets the outer mitochondrial membrane to initiate apoptosis. Structural information on the relationship between the BCL-2 family and the outer mitochondrial membrane is missing; likewise, knowledge of the biophysical mechanisms by which the outer mitochondrial membrane affects and effects apoptosis is lacking. In this mini-review, we provide a current overview of the BCL-2 family members and discuss the latest structural insights into BAK/BAX activation and oligomerization in the context of the outer mitochondrial membrane and mitochondrial biology.
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Affiliation(s)
- Mark P.A. Luna-Vargas
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
| | - Jerry E. Chipuk
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
- The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
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Iyer S, Anwari K, Alsop AE, Yuen WS, Huang DCS, Carroll J, Smith NA, Smith BJ, Dewson G, Kluck RM. Identification of an activation site in Bak and mitochondrial Bax triggered by antibodies. Nat Commun 2016; 7:11734. [PMID: 27217060 PMCID: PMC4890306 DOI: 10.1038/ncomms11734] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 04/25/2016] [Indexed: 12/31/2022] Open
Abstract
During apoptosis, Bak and Bax are activated by BH3-only proteins binding to the α2–α5 hydrophobic groove; Bax is also activated via a rear pocket. Here we report that antibodies can directly activate Bak and mitochondrial Bax by binding to the α1–α2 loop. A monoclonal antibody (clone 7D10) binds close to α1 in non-activated Bak to induce conformational change, oligomerization, and cytochrome c release. Anti-FLAG antibodies also activate Bak containing a FLAG epitope close to α1. An antibody (clone 3C10) to the Bax α1–α2 loop activates mitochondrial Bax, but blocks translocation of cytosolic Bax. Tethers within Bak show that 7D10 binding directly extricates α1; a structural model of the 7D10 Fab bound to Bak reveals the formation of a cavity under α1. Our identification of the α1–α2 loop as an activation site in Bak paves the way to develop intrabodies or small molecules that directly and selectively regulate these proteins. During apoptosis, Bak and Bax are activated by BH3-only proteins binding to a specific hydrophobic groove. Here, the authors show that antibodies can also activate Bak and mitochondrial Bax by binding to the α1-α2 loop, thus identifying a potential clinical target.
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Affiliation(s)
- Sweta Iyer
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Victoria 3052, Australia
| | - Khatira Anwari
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Victoria 3052, Australia
| | - Amber E Alsop
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Victoria 3052, Australia
| | - Wai Shan Yuen
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - David C S Huang
- Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Victoria 3052, Australia
| | - John Carroll
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - Nicholas A Smith
- Department of Chemistry and Physics, La Trobe Institute for Molecular Sciences, La Trobe University, Victoria 3086, Australia
| | - Brian J Smith
- Department of Chemistry and Physics, La Trobe Institute for Molecular Sciences, La Trobe University, Victoria 3086, Australia
| | - Grant Dewson
- Cell Signalling and Cell Death Division, The Walter and Eliza Hall Institute of Medical Research, Victoria 3052, Australia
| | - Ruth M Kluck
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Victoria 3052, Australia
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O'Neill KL, Huang K, Zhang J, Chen Y, Luo X. Inactivation of prosurvival Bcl-2 proteins activates Bax/Bak through the outer mitochondrial membrane. Genes Dev 2016; 30:973-88. [PMID: 27056669 PMCID: PMC4840302 DOI: 10.1101/gad.276725.115] [Citation(s) in RCA: 225] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/18/2016] [Indexed: 02/06/2023]
Abstract
In this study, O'Neill et al. used genome editing to generate cells deficient for all eight proapoptotic BH3-only proteins (OctaKO) and cells that lack the entire Bcl-2 family (Bcl-2 allKO). Their findings suggest that the outer mitochondrial membrane (OMM), not BH3-only proteins or p53/Rb, is the direct activator of Bax/Bak following BH3-only-mediated neutralization of anti-apoptotic Bcl-2 proteins. The mechanism of Bax/Bak activation remains a central question in mitochondria-dependent apoptotic signaling. While it is established that all proapoptotic Bcl-2 homology 3 (BH3)-only proteins bind and neutralize the anti-apoptotic Bcl-2 family proteins, how this neutralization leads to Bax/Bak activation has been actively debated. Here, genome editing was used to generate cells deficient for all eight proapoptotic BH3-only proteins (OctaKO) and those that lack the entire Bcl-2 family (Bcl-2 allKO). Although the OctaKO cells were resistant to most apoptotic stimuli tested, they underwent Bax/Bak-dependent and p53/Rb-independent apoptosis efficiently when both Bcl-xL and Mcl-1, two anti-apoptotic Bcl-2 proteins, were inactivated or eliminated. Strikingly, when expressed in the Bcl-2 allKO cells, both Bax and Bak spontaneously associated with the outer mitochondrial membrane (OMM) through their respective helix 9, and this association triggered their homo-oligomerization/activation. Together, these results strongly suggest that the OMM, not BH3-only proteins or p53/Rb, is the long-sought-after direct activator of Bax/Bak following BH3-only-mediated neutralization of anti-apoptotic Bcl-2 proteins.
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Affiliation(s)
- Katelyn L O'Neill
- Eppley Institute for Research in Cancer and Allied Diseases, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
| | - Kai Huang
- Eppley Institute for Research in Cancer and Allied Diseases, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
| | - Jingjing Zhang
- Eppley Institute for Research in Cancer and Allied Diseases, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA; Xiangya Hospital, Central South University, Changsha 410008, China
| | - Yi Chen
- Eppley Institute for Research in Cancer and Allied Diseases, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
| | - Xu Luo
- Eppley Institute for Research in Cancer and Allied Diseases, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
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47
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Zhang Z, Subramaniam S, Kale J, Liao C, Huang B, Brahmbhatt H, Condon SGF, Lapolla SM, Hays FA, Ding J, He F, Zhang XC, Li J, Senes A, Andrews DW, Lin J. BH3-in-groove dimerization initiates and helix 9 dimerization expands Bax pore assembly in membranes. EMBO J 2015; 35:208-36. [PMID: 26702098 DOI: 10.15252/embj.201591552] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 11/18/2015] [Indexed: 01/08/2023] Open
Abstract
Pro-apoptotic Bax induces mitochondrial outer membrane permeabilization (MOMP) by forming oligomers through a largely undefined process. Using site-specific disulfide crosslinking, compartment-specific chemical labeling, and mutational analysis, we found that activated integral membrane Bax proteins form a BH3-in-groove dimer interface on the MOM surface similar to that observed in crystals. However, after the α5 helix was released into the MOM, the remaining interface with α2, α3, and α4 helices was rearranged. Another dimer interface was formed inside the MOM by two intersected or parallel α9 helices. Combinations of these interfaces generated oligomers in the MOM. Oligomerization was initiated by BH3-in-groove dimerization, without which neither the other dimerizations nor MOMP occurred. In contrast, α9 dimerization occurred downstream and was required for release of large but not small proteins from mitochondria. Moreover, the release of large proteins was facilitated by α9 insertion into the MOM and localization to the pore rim. Therefore, the BH3-in-groove dimerization on the MOM nucleates the assembly of an oligomeric Bax pore that is enlarged by α9 dimerization at the rim.
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Affiliation(s)
- Zhi Zhang
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | | | - Justin Kale
- Biological Sciences, Sunnybrook Research Institute, Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Chenyi Liao
- Department of Chemistry, University of Vermont, Burlington, VT, USA
| | - Bo Huang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hetal Brahmbhatt
- Biological Sciences, Sunnybrook Research Institute, Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Samson G F Condon
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Suzanne M Lapolla
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Franklin A Hays
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Jingzhen Ding
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Feng He
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Xuejun C Zhang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jianing Li
- Department of Chemistry, University of Vermont, Burlington, VT, USA
| | - Alessandro Senes
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - David W Andrews
- Biological Sciences, Sunnybrook Research Institute, Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Jialing Lin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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