1
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Nguyen D, Osterlund E, Kale J, Andrews DW. The C-terminal sequences of Bcl-2 family proteins mediate interactions that regulate cell death. Biochem J 2024; 481:903-922. [PMID: 38985308 DOI: 10.1042/bcj20210352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 07/11/2024]
Abstract
Programmed cell death via the both intrinsic and extrinsic pathways is regulated by interactions of the Bcl-2 family protein members that determine whether the cell commits to apoptosis via mitochondrial outer membrane permeabilization (MOMP). Recently the conserved C-terminal sequences (CTSs) that mediate localization of Bcl-2 family proteins to intracellular membranes, have been shown to have additional protein-protein binding functions that contribute to the functions of these proteins in regulating MOMP. Here we review the pivotal role of CTSs in Bcl-2 family interactions including: (1) homotypic interactions between the pro-apoptotic executioner proteins that cause MOMP, (2) heterotypic interactions between pro-apoptotic and anti-apoptotic proteins that prevent MOMP, and (3) heterotypic interactions between the pro-apoptotic executioner proteins and the pro-apoptotic direct activator proteins that promote MOMP.
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Affiliation(s)
- Dang Nguyen
- Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Canada
- Biological Sciences Platform, Odette Cancer Program, Sunnybrook Research Institute, Toronto, Canada
| | - Elizabeth Osterlund
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Science, McMaster University, Hamilton, Canada
| | - Justin Kale
- Biological Sciences Platform, Odette Cancer Program, Sunnybrook Research Institute, Toronto, Canada
| | - David W Andrews
- Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Canada
- Biological Sciences Platform, Odette Cancer Program, Sunnybrook Research Institute, Toronto, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Canada
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2
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Chota A, George BP, Abrahamse H. Apoptotic efficiency of Dicoma anomala biosynthesized silver nanoparticles against A549 lung cancer cells. Biomed Pharmacother 2024; 176:116845. [PMID: 38810403 DOI: 10.1016/j.biopha.2024.116845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/21/2024] [Accepted: 05/26/2024] [Indexed: 05/31/2024] Open
Abstract
Lung cancer is one of the common forms of cancer that affects both men and women and is regarded as the leading cause of cancer related deaths. It is characterized by unregulated cell division of altered cells within the lung tissues. Green nanotechnology is a promising therapeutic option that is adopted in cancer research. Dicoma anomala (D. anomala) is one of the commonly used African medicinal plant in the treatment of different medical conditions including cancer. In the present study, silver nanoparticles (AgNPs) were synthesized using D. anomala MeOH root extract. We evaluated the anticancer efficacy of the synthesized AgNPs as an individual treatment as well as in combination with pheophorbide a (PPBa) mediated photodynamic therapy (PDT) in vitro. UV-VIS spectroscopy, high-resolution transmission electron microscopy (HR-TEM), Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) was used to confirm the formation of D.A AgNPs. Post 24 h treatment, A549 cells were evaluated for ATP proliferation, morphological changes supported by LIVE/DEAD assay, and caspase activities. All experiments were repeated four times (n=4), with findings being analysed using SPSS statistical software version 27 set at 0.95 confidence interval. The results from the present study revealed a dose-dependent decrease in cell proliferation in both individual and combination therapy of PPBa mediated PDT and D.A AgNPs on A549 lung cancer cells with significant morphological changes. Additionally, LIVE/DEAD assay displayed a significant increase in the number of dead cell population in individual treatments (i.e., IC50's treated A549 cells) as well as in combination therapy. In conclusion, the findings from this study demonstrated the anticancer efficacy of green synthesized AgNPs as a mono-therapeutic drug as well as in combination with a chlorophyll derivative PPBa in PDT. Taken together, the findings highlight the therapeutic potential of green nanotechnology in medicine.
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Affiliation(s)
- Alexander Chota
- Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, P.O. Box 1711, Doornfontein, Johannesburg 2028, South Africa
| | - Blassan P George
- Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, P.O. Box 1711, Doornfontein, Johannesburg 2028, South Africa.
| | - Heidi Abrahamse
- Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, P.O. Box 1711, Doornfontein, Johannesburg 2028, South Africa
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3
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Pandey R, Bisht P, Wal P, Murti K, Ravichandiran V, Kumar N. SMAC Mimetics for the Treatment of Lung Carcinoma: Present Development and Future Prospects. Mini Rev Med Chem 2024; 24:1334-1352. [PMID: 38275029 DOI: 10.2174/0113895575269644231120104501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/07/2023] [Accepted: 10/10/2023] [Indexed: 01/27/2024]
Abstract
BACKGROUND Uncontrolled cell growth and proliferation, which originate from lung tissue often lead to lung carcinoma and are more likely due to smoking as well as inhaled environmental toxins. It is widely recognized that tumour cells evade the ability of natural programmed death (apoptosis) and facilitates tumour progression and metastasis. Therefore investigating and targeting the apoptosis pathway is being utilized as one of the best approaches for decades. OBJECTIVE This review describes the emergence of SMAC mimetic drugs as a treatment approach, its possibilities to synergize the response along with current limitations as well as future perspective therapy for lung cancer. METHOD Articles were analysed using search engines and databases namely Pubmed and Scopus. RESULT Under cancerous circumstances, the level of Inhibitor of Apoptosis Proteins (IAPs) gets elevated, which suppresses the pathway of programmed cell death, plus supports the proliferation of lung cancer. As it is a major apoptosis regulator, natural drugs that imitate the IAP antagonistic response like SMAC mimetic agents/Diablo have been identified to trigger cell death. SMAC i.e. second mitochondria activators of caspases is a molecule produced by mitochondria, stimulates apoptosis by neutralizing/inhibiting IAP and prevents its potential responsible for the activation of caspases. Various preclinical data have proven that these agents elicit the death of lung tumour cells. Apart from inducing apoptosis, these also sensitize the cancer cells toward other effective anticancer approaches like chemo, radio, or immunotherapies. There are many SMAC mimetic agents such as birinapant, BV-6, LCL161, and JP 1201, which have been identified for diagnosis as well as treatment purposes in lung cancer and are also under clinical investigation. CONCLUSION SMAC mimetics acts in a restorative way in the prevention of lung cancer.
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Affiliation(s)
- Ruchi Pandey
- Department of Pharmacology & Toxicology, National Institute of Pharmaceutical Education & Research (NIPER), Hajipur, Bihar, 844102, India
| | - Priya Bisht
- Department of Pharmacology & Toxicology, National Institute of Pharmaceutical Education & Research (NIPER), Hajipur, Bihar, 844102, India
| | - Pranay Wal
- Department of Pharmacy, Pranveer Singh Institute of Technology, Kanpur, Uttar Pradesh, India
| | - Krishna Murti
- Department of Pharmacy Practice, National Institute of Pharmaceutical Education & Research (NIPER), Hajipur, Bihar, 844102, India
| | - V Ravichandiran
- Department of Pharmacology & Toxicology, National Institute of Pharmaceutical Education & Research (NIPER), Hajipur, Bihar, 844102, India
| | - Nitesh Kumar
- Department of Pharmacology & Toxicology, National Institute of Pharmaceutical Education & Research (NIPER), Hajipur, Bihar, 844102, India
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4
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Gonzalo Ó, Benedi A, Vela L, Anel A, Naval J, Marzo I. Study of the Bcl-2 Interactome by BiFC Reveals Differences in the Activation Mechanism of Bax and Bak. Cells 2023; 12:cells12050800. [PMID: 36899936 PMCID: PMC10000386 DOI: 10.3390/cells12050800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/23/2023] [Accepted: 02/28/2023] [Indexed: 03/08/2023] Open
Abstract
Evasion of apoptosis is one of the hallmarks of cancer cells. Proteins of the Bcl-2 family are key regulators of the intrinsic pathway of apoptosis, and alterations in some of these proteins are frequently found in cancer cells. Permeabilization of the outer mitochondrial membrane, regulated by pro- and antiapoptotic members of the Bcl-2 family of proteins, is essential for the release of apoptogenic factors leading to caspase activation, cell dismantlement, and death. Mitochondrial permeabilization depends on the formation of oligomers of the effector proteins Bax and Bak after an activation event mediated by BH3-only proteins and regulated by antiapoptotic members of the Bcl-2 family. In the present work, we have studied interactions between different members of the Bcl-2 family in living cells via the BiFC technique. Despite the limitations of this technique, present data suggest that native proteins of the Bcl-2 family acting inside living cells establish a complex network of interactions, which would fit nicely into "mixed" models recently proposed by others. Furthermore, our results point to differences in the regulation of Bax and Bak activation by proteins of the antiapoptotic and BH3-only subfamilies. We have also applied the BiFC technique to explore the different molecular models proposed for Bax and Bak oligomerization. Bax and Bak's mutants lacking the BH3 domain were still able to associate and give BiFC signals, suggesting the existence of alternative surfaces of interaction between two Bax or Bak molecules. These results agree with the widely accepted symmetric model for the dimerization of these proteins and also suggest that other regions, different from the α6 helix, could be involved in the oligomerization of BH3-in groove dimers.
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5
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Wolf P, Schoeniger A, Edlich F. Pro-apoptotic complexes of BAX and BAK on the outer mitochondrial membrane. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119317. [PMID: 35752202 DOI: 10.1016/j.bbamcr.2022.119317] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/02/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
In multicellular organisms the regulated cell death apoptosis is critically important for both ontogeny and homeostasis. Mitochondria are indispensable for stress-induced apoptosis. The BCL-2 protein family controls mitochondrial apoptosis and initiates cell death through the pro-apoptotic activities of BAX and BAK at the outer mitochondrial membrane (OMM). Cellular survival is ensured by the retrotranslocation of mitochondrial BAX and BAK into the cytosol by anti-apoptotic BCL-2 proteins. BAX/BAK-dependent OMM permeabilization releases the mitochondrial cytochrome c (cyt c), which initiates activation of caspase-9. The caspase cascade leads to cell shrinkage, plasma membrane blebbing, chromatin condensation, and apoptotic body formation. Although it is clear that ultimately complexes of active BAX and BAK commit the cell to apoptosis, the nature of these complexes is still enigmatic. Excessive research has described a range of complexes, varying from a few molecules to several 10,000, in different systems. BAX/BAK complexes potentially form ring-like structures that could expose the inner mitochondrial membrane. It has been suggested that these pores allow the efflux of small proteins and even mitochondrial DNA. Here we summarize the current state of knowledge for mitochondrial BAX/BAK complexes and the interactions between these proteins and the membrane.
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Affiliation(s)
- Philipp Wolf
- Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Axel Schoeniger
- Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Frank Edlich
- Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, 04103 Leipzig, Germany.
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6
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Gahl RF. Expanding the Biological Importance of Protein Structures: Insight into Dynamic Biological Function from Protein Folding Theory Analyses. J Phys Chem B 2022; 126:6438-6445. [PMID: 35984908 DOI: 10.1021/acs.jpcb.2c04581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While recent developments in the determination of the three-dimensional structure of proteins have rapidly progressed, there remains a difficult challenge of studying proteins that exhibit dynamic behavior as part of their biological functions in environments considerably different than how their three-dimensional structure was determined. This study investigates the dynamic behavior of Bax, a member of the Bcl-2 family of proteins, during the regulation of apoptosis in the context of its published three-dimensional structure. The location of Bax in live cells is an equilibrium between the cytosol and outer-mitochondrial membrane. However, the regions of Bax that have been determined to be responsible for this equilibrium are shown to be inaccessible to engage in these interactions, namely, the C-terminal helix, according to the solved three-dimensional structure. Therefore, the analyses that have been applied to identify chain folding initiation sites (CFIS) and propose unfolding pathways have also been applied to the three-dimensional structure of Bax to provide a rationale for how Bax can engage in the dynamic behavior that is part of its biological function. The analyses identified regions in Bax that contribute to its stability and regions that could be susceptible to conformational changes, including the C-terminal helix, and, consequently, dynamic behavior. Experimental observations confirmed the classification of these regions. Consequently, the utilization of methods to identify CFIS on three-dimensional structures can be an effective tool to help expand our knowledge about the biological function of proteins that exhibit dynamic behavior.
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Affiliation(s)
- Robert F Gahl
- Division of Extramural Activities, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20850, United States
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7
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BAX mitochondrial integration is regulated allosterically by its α1-α2 loop. Cell Death Differ 2021; 28:3270-3281. [PMID: 34135480 DOI: 10.1038/s41418-021-00815-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 11/08/2022] Open
Abstract
The conformational changes converting BAX from an inert cytosolic monomer into the homo-oligomers that permeabilize the mitochondrial outer membrane (MOM) are crucial steps toward apoptosis. Here, we have explored the potential role of the BAX α1-α2 loop in this process by three mutagenic approaches: replacing loop segments with cognate loop regions from closely related proteins, alanine scanning and analysis of BAX α1-α2 loop missense mutations observed in tumours. Responsiveness to a death signal, such as tBID, was reduced by mutations in the N-terminal but not C-terminal half of the loop. N-terminal loop variants, which were enriched in tumours, impaired MOM integration by allosterically reducing exposure of the BAX α9 transmembrane anchor. Most C-terminal loop variants reduced BAX stability, leading to increased BAX apoptotic function in some variants. Thus, our systematic mutagenesis suggests that the two halves of the α1-α2 loop have distinct functions. We show that the N-terminal half of the loop (its first nine residues) comprises an important allosteric regulator of BAX activation by setting the proportion of MOM-integrated BAX following a death signal. The enrichment of N-terminal loop mutations in tumours indicates that they may promote tumour cell survival and underscore the loop as a target for therapeutic manipulation of BAX function.
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8
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Lv F, Qi F, Zhang Z, Wen M, Kale J, Piai A, Du L, Wang S, Zhou L, Yang Y, Wu B, Liu Z, Del Rosario J, Pogmore J, Chou JJ, Andrews DW, Lin J, OuYang B. An amphipathic Bax core dimer forms part of the apoptotic pore wall in the mitochondrial␣membrane. EMBO J 2021; 40:e106438. [PMID: 34101209 PMCID: PMC8280806 DOI: 10.15252/embj.2020106438] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 04/17/2021] [Accepted: 04/27/2021] [Indexed: 02/01/2023] Open
Abstract
Bax proteins form pores in the mitochondrial outer membrane to initiate apoptosis. This might involve their embedding in the cytosolic leaflet of the lipid bilayer, thus generating tension to induce a lipid pore with radially arranged lipids forming the wall. Alternatively, Bax proteins might comprise part of the pore wall. However, there is no unambiguous structural evidence for either hypothesis. Using NMR, we determined a high-resolution structure of the Bax core region, revealing a dimer with the nonpolar surface covering the lipid bilayer edge and the polar surface exposed to water. The dimer tilts from the bilayer normal, not only maximizing nonpolar interactions with lipid tails but also creating polar interactions between charged residues and lipid heads. Structure-guided mutations demonstrate the importance of both types of protein-lipid interactions in Bax pore assembly and core dimer configuration. Therefore, the Bax core dimer forms part of the proteolipid pore wall to permeabilize mitochondria.
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Affiliation(s)
- Fujiao Lv
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Fei Qi
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Zhi Zhang
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Maorong Wen
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Justin Kale
- Biological Sciences, Sunnybrook Research Institute, University of Toronto, Toronto, ON, Canada
| | - Alessandro Piai
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Lingyu Du
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Shuqing Wang
- School of Pharmacy, Tianjin Medical University, Tianjin, China
| | - Liujuan Zhou
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yaqing Yang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Bin Wu
- National Facility for Protein Science in Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Zhijun Liu
- National Facility for Protein Science in Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Juan Del Rosario
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Justin Pogmore
- Biological Sciences, Sunnybrook Research Institute, University of Toronto, Toronto, ON, Canada
| | - James J Chou
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - David W Andrews
- Biological Sciences, Sunnybrook Research Institute, University of Toronto, Toronto, ON, Canada
| | - Jialing Lin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.,Stephenson Cancer Center, Oklahoma City, OK, USA
| | - Bo OuYang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
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9
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Morris DL, Tjandra N. Inducible fold-switching as a mechanism to fibrillate pro-apoptotic BCL-2 proteins. Biopolymers 2021; 112:e23424. [PMID: 33764501 DOI: 10.1002/bip.23424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/18/2021] [Accepted: 03/05/2021] [Indexed: 12/12/2022]
Abstract
Neurodegenerative diseases often are associated with cellular dysregulation that results in premature cell death or apoptosis. A common example is the accumulation of amyloid plaques that promotes the excessive expression of p38 mitogen-activated protein kinase. The increased abundance of this enzyme leads to mass phosphorylation and activation of a protein from the B-cell lymphoma 2 (BCL-2) family, BAX. BAX is the central regulatory protein for mitochondrial outer membrane permeabilization (MOMP), a poration process that commits cells to apoptosis by releasing death-propagating factors from the mitochondria. Recent reports identify a naturally occurring peptide, Humanin (HN), that could block amyloid-beta-associated neuronal apoptosis by interacting with BCL-2 proteins. We recently showed humanin interaction leads to the amyloid-like fibrillation of BAX and a second BCL-2 family member, BID. We proposed this as a novel anti-apoptotic mechanism that inhibits pro-apoptotic BCL-2 proteins from initiating MOMP by sequestering them into fibrils, a heretofore unprecedented phenomenon that involves refolding globular BCL-2 proteins rapidly into fibrils where they undergo significant alpha-helix to beta-sheet fold-switching. Here we seek to further characterize the fibrillation and fold-switch in conditions that are known to induce amyloid fibrillation.
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Affiliation(s)
- Daniel L Morris
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Nico Tjandra
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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10
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Cohen DT, Wales TE, McHenry MW, Engen JR, Walensky LD. Site-Dependent Cysteine Lipidation Potentiates the Activation of Proapoptotic BAX. Cell Rep 2021; 30:3229-3239.e6. [PMID: 32160532 PMCID: PMC7343539 DOI: 10.1016/j.celrep.2020.02.057] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 12/23/2019] [Accepted: 02/11/2020] [Indexed: 11/19/2022] Open
Abstract
BCL-2 family proteins converge at the mitochondrial outer membrane to regulate apoptosis and maintain the critical balance between cellular life and death. This physiologic process is essential to organism homeostasis and relies on protein-protein and protein-lipid interactions among BCL-2 family proteins in the mitochondrial lipid environment. Here, we find that trans-2-hexadecenal (t-2-hex), previously implicated in regulating BAX-mediated apoptosis, does so by direct covalent reaction with C126, which is located on the surface of BAX at the junction of its α5/α6 core hydrophobic hairpin. The application of nuclear magnetic resonance spectroscopy, hydrogen-deuterium exchange mass spectrometry, specialized t-2-hex-containing liposomes, and BAX mutational studies in mitochondria and cells reveals structure-function insights into the mechanism by which covalent lipidation at the mitochondria sensitizes direct BAX activation. The functional role of BAX lipidation as a control point of mitochondrial apoptosis could provide a therapeutic strategy for BAX modulation by chemical modification of C126. Cohen et al. show that trans-2-hexadecenal (t-2-hex) potentiates BAX-mediated apoptosis by non-enzymatic covalent lipidation of BAX C126. t-2-hex derivatization induces BAX-activating conformational changes and enhances BH3-triggered BAX poration of liposomal and mitochondrial membranes in a C126-dependent manner. This mechanism informs a therapeutic strategy for modulating BAX-mediated apoptosis by targeting C126.
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Affiliation(s)
- Daniel T Cohen
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA; Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Thomas E Wales
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Matthew W McHenry
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA; Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Loren D Walensky
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA; Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA.
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11
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Gao K, Liu M, Li Y, Wang L, Zhao C, Zhao X, Zhao J, Ding Y, Tang H, Jia Y, Wang J, Wen A. Lyciumamide A, a dimer of phenolic amide, protects against NMDA-induced neurotoxicity and potential mechanisms in vitro. J Mol Histol 2021; 52:449-459. [PMID: 33755822 DOI: 10.1007/s10735-020-09952-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 12/28/2020] [Indexed: 12/24/2022]
Abstract
Currently, the excessive activation of N-methyl-D-aspartate receptors (NMDARs) is considered to be a crucial mechanism of brain injury. Lycium barbarum A (LyA) is a dimer of phenol amides isolated from the fruit of Lycium barbarum. Our previous studies have shown that LyA has potential antioxidant activity. This study aimed to explore the neuroprotective effect of LyA and its potential mechanism. Firstly, the molecular docking was used to preliminarily explore the potential function of LyA to block NMDAR. Then, the ability of LyA was further verified by NMDA-induced human neuroblastoma SH-SY5Y cells in vivo. Treatment with LyA significantly attenuated NMDA-induced neuronal insults by increasing cell viability, reducing lactate dehydrogenase (LDH) release, and increasing cell survival. Meanwhile, LyA significantly reversed the increase in intracellular calcium and in ROS production induced by NMDA. Finally, the western blot indicated that LyA could suppress the Ca2+ influx and increase the p-NR2B, p-CaMKII, p-JNK, and p-p38 level induced by NMDA. These above findings provide evidence that LyA protect against brain injury, and restraining NMDARs and suppressing mitochondrial oxidative stress and inhibiting cell apoptosis may be involved in the protective mechanism.
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Affiliation(s)
- Kai Gao
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Meiyou Liu
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Yuan Li
- Department of Pharmacy, Xi'an Children's Hospital, Xi'an, China
| | - Lei Wang
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Chao Zhao
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Xian Zhao
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Jinyi Zhao
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Yi Ding
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Haifeng Tang
- Institute of Materia Medica, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Yanyan Jia
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China.
| | - Jingwen Wang
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China.
| | - Aidong Wen
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China.
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12
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Soond SM, Savvateeva LV, Makarov VA, Gorokhovets NV, Townsend PA, Zamyatnin AA. Cathepsin S Cleaves BAX as a Novel and Therapeutically Important Regulatory Mechanism for Apoptosis. Pharmaceutics 2021; 13:pharmaceutics13030339. [PMID: 33807987 PMCID: PMC8035670 DOI: 10.3390/pharmaceutics13030339] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 02/08/2021] [Accepted: 03/01/2021] [Indexed: 12/11/2022] Open
Abstract
Certain lysosomal cathepsin proteins have come into focus as being good candidates for therapeutic targeting, based on them being over-expressed in a variety of cancers and based on their regulation of the apoptotic pathway. Here, we report novel findings that highlight the ability of cathepsin S expression to be up-regulated under Paclitaxel-stimulatory conditions in kidney cell lines and it being able to cleave the apoptotic p21 BAX protein in intact cells and in vitro. Consistent with this, we demonstrate that this effect can be abrogated in vitro and in mammalian cells under conditions that utilize dominant-inhibitory cathepsin S expression, cathepsin S expression-knockdown and through the activity of a novel peptide inhibitor, CS-PEP1. Moreover, we report a unique role for cathepsin S in that it can cleave a polyubiquitinated-BAX protein intermediate and is a step that may contribute to down-regulating post-translationally-modified levels of BAX protein. Finally, CS-PEP1 may possess promising activity as a potential anti-cancer therapeutic against chemotherapeutic-resistant Renal Clear Cell Carcinoma kidney cancer cells and for combined uses with therapeutics such as Paclitaxel.
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Affiliation(s)
- Surinder M. Soond
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, 119991 Moscow, Russia; (L.V.S.); (V.A.M.); (N.V.G.)
- Correspondence: (S.M.S.); (A.A.Z.J.)
| | - Lyudmila V. Savvateeva
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, 119991 Moscow, Russia; (L.V.S.); (V.A.M.); (N.V.G.)
| | - Vladimir A. Makarov
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, 119991 Moscow, Russia; (L.V.S.); (V.A.M.); (N.V.G.)
| | - Neonila V. Gorokhovets
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, 119991 Moscow, Russia; (L.V.S.); (V.A.M.); (N.V.G.)
| | - Paul A. Townsend
- Division of Cancer Sciences and Manchester Cancer Research Centre, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK;
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7X, UK
| | - Andrey A. Zamyatnin
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, 119991 Moscow, Russia; (L.V.S.); (V.A.M.); (N.V.G.)
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
- Department of Biotechnology, Sirius University of Science and Technology, 1 Olympic Ave, 354340 Sochi, Russia
- Correspondence: (S.M.S.); (A.A.Z.J.)
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13
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Price DA, Hill TD, Hutson KA, Rightnowar BW, Moran SD. Membrane-dependent amyloid aggregation of human BAX α9 (173-192). Protein Sci 2021; 30:1072-1080. [PMID: 33641228 DOI: 10.1002/pro.4053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 02/08/2021] [Accepted: 02/24/2021] [Indexed: 11/07/2022]
Abstract
Mitochondrial outer membrane permeabilization, which is a critical step in apoptosis, is initiated upon transmembrane insertion of the C-terminal α-helix (α9) of the proapoptotic Bcl-2 family protein BAX. The isolated α9 fragment (residues 173-192) is also competent to disrupt model membranes, and the structures of its membrane-associated oligomers are of interest in understanding the potential roles of this sequence in apoptosis. Here, we used ultrafast two-dimensional infrared (2D IR) spectroscopy, thioflavin T binding, and transmission electron microscopy to show that the synthetic BAX α9 peptide (α9p) forms amyloid aggregates in aqueous environments and on the surfaces of anionic small unilamellar vesicles. Its inherent amyloidogenicity was predicted by sequence analysis, and 2D IR spectra reveal that vesicles modulate the β-sheet structures of insoluble aggregates, motivating further examination of the formation or suppression of BAX amyloids in apoptosis.
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Affiliation(s)
- David A Price
- Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, Illinois, USA
| | - Tayler D Hill
- Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, Illinois, USA
| | - Kaitlyn A Hutson
- Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, Illinois, USA
| | - Blaze W Rightnowar
- Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, Illinois, USA
| | - Sean D Moran
- Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, Illinois, USA
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14
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The Impact of Mitochondrial Fission-Stimulated ROS Production on Pro-Apoptotic Chemotherapy. BIOLOGY 2021; 10:biology10010033. [PMID: 33418995 PMCID: PMC7825353 DOI: 10.3390/biology10010033] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/29/2020] [Accepted: 01/01/2021] [Indexed: 02/06/2023]
Abstract
Cancer is one of the world's deadliest afflictions. Despite recent advances in diagnostic and surgical technologies, as well as improved treatments of some individual tumor types, there is currently no universal cure to prevent or impede the uncontrolled proliferation of malignant cells. Targeting tumors by inducing apoptosis is one of the pillars of cancer treatment. Changes in mitochondrial morphology precede intrinsic apoptosis, but mitochondrial dynamics has only recently been recognized as a viable pharmacological target. In many cancers, oncogenic transformation is accompanied by accumulation of elevated cellular levels of ROS leading to redox imbalance. Hence, a common chemotherapeutic strategy against such tumor types involves deploying pro-oxidant agents to increase ROS levels above an apoptotic death-inducing threshold. The aim of this chapter is to investigate the benefit of stimulating mitochondrial fission-dependent production of ROS for enhanced killing of solid tumors. The main question to be addressed is whether a sudden and abrupt change in mitochondrial shape toward the fragmented phenotype can be pharmacologically harnessed to trigger a burst of mitochondrial ROS sufficient to initiate apoptosis specifically in cancer cells but not in non-transformed healthy tissues.
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15
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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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16
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Robust autoactivation for apoptosis by BAK but not BAX highlights BAK as an important therapeutic target. Cell Death Dis 2020; 11:268. [PMID: 32327636 PMCID: PMC7181796 DOI: 10.1038/s41419-020-2463-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/05/2020] [Accepted: 04/06/2020] [Indexed: 02/08/2023]
Abstract
BAK and BAX, which drive commitment to apoptosis, are activated principally by certain BH3-only proteins that bind them and trigger major rearrangements. One crucial conformation change is exposure of their BH3 domain which allows BAK or BAX to form homodimers, and potentially to autoactivate other BAK and BAX molecules to ensure robust pore formation and cell death. Here, we test whether full-length BAK or mitochondrial BAX that are specifically activated by antibodies can then activate other BAK or BAX molecules. We found that antibody-activated BAK efficiently activated BAK as well as mitochondrial or cytosolic BAX, but antibody-activated BAX unexpectedly proved a poor activator. Notably, autoactivation by BAK involved transient interactions, as BAK and BAX molecules it activated could dissociate and homodimerize. The results suggest that BAK-driven autoactivation may play a substantial role in apoptosis, including recruitment of BAX to the mitochondria. Hence, directly targeting BAK rather than BAX may prove particularly effective in inhibiting unwanted apoptosis, or alternatively, inducing apoptosis in cancer cells.
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17
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PEGylation-based strategy to identify pathways involved in the activation of apoptotic BAX protein. Biochim Biophys Acta Gen Subj 2020; 1864:129541. [PMID: 31987956 DOI: 10.1016/j.bbagen.2020.129541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 10/25/2022]
Abstract
BACKGROUND BAX activation is a crucial step for commitment to apoptosis. Several activators, such as BimBH3-based therapeutic peptides and cleaved Bid (cBid) protein, can trigger BAX-mediated apoptosis, but it is unclear whether they proceed through the same pathway. METHODS Here we utilize PEGylation-based approach, which is shown to efficiently shield individual binding grooves in BAX from activators, to investigate and reveal that the activators take different routes to induce BAX-mediated apoptosis. Various spectroscopic/biochemical tools, including electron spin resonance, circular dichroism, fluorescence recovery after photobleaching, and label-transfer assay, were employed to reveal details in the processes. RESULTS We observe a key mutant BAX 164-PEG that acts differently in response to cBid and BimBH3 stimuli. While BimBH3 directly interacts with the trigger groove (TG) to induce the conformational changes in BAX that includes the release of α9 from the canonical groove (CG) and oligomerization, cBid engages with CG and works with mitochondrial lipids to fully activate BAX. CONCLUSION PEGylation-based approach is proven useful to shield individual binding grooves of BAX from apoptotic stimuli. Groove engagement in CG of BAX is required for a full cBid-induced BAX activation. This study has identified differences in the pathways involved during the initiation of BAX activation by full-length cBid protein versus synthetic BimBH3-based peptides. GENERAL SIGNIFICANCE Our finding is potentially valuable for therapeutic application as the pore-forming activity of 164-PEG is independent from the cBid-mediated apoptotic pathways, but can be administrated by the synthetic short peptides.
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18
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Morris DL, Kastner DW, Johnson S, Strub MP, He Y, Bleck CKE, Lee DY, Tjandra N. Humanin induces conformational changes in the apoptosis regulator BAX and sequesters it into fibers, preventing mitochondrial outer-membrane permeabilization. J Biol Chem 2019; 294:19055-19065. [PMID: 31690630 DOI: 10.1074/jbc.ra119.011297] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/31/2019] [Indexed: 01/27/2023] Open
Abstract
The mitochondrial, or intrinsic, apoptosis pathway is regulated mainly by members of the B-cell lymphoma 2 (BCL-2) protein family. BCL-2-associated X apoptosis regulator (BAX) plays a pivotal role in the initiation of mitochondria-mediated apoptosis as one of the factors causing mitochondrial outer-membrane permeabilization (MOMP). Of current interest are endogenous BAX ligands that inhibit its MOMP activity. Mitochondrial-derived peptides (MDPs) are a recently identified class of mitochondrial retrograde signaling molecules and are reported to be potent apoptosis inhibitors. Among them, humanin (HN) has been shown to suppress apoptosis by inhibiting BAX translocation to the mitochondrial outer membrane, but the molecular mechanism of this interaction is unknown. Here, using recombinant protein expression, along with light-scattering, CD, and fluorescence spectroscopy, we report that HN and BAX can form fibers together in vitro Results from negative stain EM experiments suggest that BAX undergoes secondary and tertiary structural rearrangements and incorporates into the fibers, and that its membrane-associating C-terminal helix is important for the fibrillation process. Additionally, HN mutations known to alter its anti-apoptotic activity affect fiber morphology. Our findings reveal for the first time a potential mechanism by which BAX can be sequestered by fibril formation, which can prevent it from initiating MOMP and committing the cell to apoptosis.
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Affiliation(s)
- Daniel L Morris
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814
| | - David W Kastner
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814
| | - Sabrina Johnson
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814
| | - Marie-Paule Strub
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814.,Protein Expression Facility, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814
| | - Yi He
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814.,Protein Expression Facility, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814
| | - Christopher K E Bleck
- Electron Microscopy Core Facility, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Duck-Yeon Lee
- Biochemistry Core Facility, NHLBI, National Institutes of Health, Bethesda, Maryland 20814
| | - Nico Tjandra
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20814
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19
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Liu Z, Lang B, Gao M, Chang X, Guan Q, Xu Q, Wu D, Li Z, Zuo D, Zhang W, Wu Y. 3-(3-Methoxyphenyl)-6-(3-amino-4-methoxyphenyl)-7H-[1,2,4] triazolo [3,4-b][1,3,4] thiadiazine, a novel tubulin inhibitor, evokes G2/M cell cycle arrest and apoptosis in SGC-7901 and HeLa cells. J Cell Biochem 2019; 121:2184-2196. [PMID: 31642107 DOI: 10.1002/jcb.29442] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 10/10/2019] [Indexed: 12/14/2022]
Abstract
Gastric cancer and cervical cancer are two major malignant tumors that threaten human health. The novel chemotherapeutic drugs are needed urgently to treat gastric cancer and cervical cancer with high anticancer activity and metabolic stability. Previously we have reported the synthesis, characterization and identification of a novel combretastatin A-4 analog, 3-(3-methoxyphenyl)-6-(3-amino-4- methoxyphenyl) -7H-[1,2,4]triazolo[3,4-b][1,3,4] thiadiazine (XSD-7). In this study, we sought to investigate its anticancer mechanisms in a human gastric cancer cell line (SGC-7901 cells) and human cervical carcinoma cell line (HeLa cells). The 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay showed that XSD-7 induced cytotoxicity in SGC-7901 and HeLa cells with inhibitory concentration 50 values of 0.11 ± 0.03 and 0.12 ± 0.05 µM, respectively. Immunofluorescence studies proved that XSD-7 inhibited microtubule polymerization during cell division in SGC-7901 and HeLa cells. Then, these cells were arrested at G2/M cell cycle and subsequently progressed into apoptosis. In further study, mitochondrial membrane potential analysis and Western blot analysis demonstrated that XSD-7 treatment-induced SGC-7901 cell apoptosis via both the mitochondria-mediated pathway and the death receptor-mediated pathway. In contrast, XSD-7 induced apoptosis in HeLa cells mainly via the mitochondria-mediated pathway. Hence, our data indicate that XSD-7 exerted antiproliferative activity by disrupting microtubule dynamics, leading to cell cycle arrest, and eventually inducing cell apoptosis. XSD-7 with novel structure has the potential to be developed for therapeutic treatment of gastric cancer and cervical cancer.
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Affiliation(s)
- Zi Liu
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Binyue Lang
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Minghuan Gao
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Xing Chang
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Qi Guan
- Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Qile Xu
- Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Di Wu
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Zengqiang Li
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Daiying Zuo
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Weige Zhang
- Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
| | - Yingliang Wu
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Shenhe, China
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20
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He Y, Chen Y, Morris DL, Lee DY, Tjandra N. Bax expression is optimal at low oxygen tension and constant agitation. Protein Expr Purif 2019; 165:105501. [PMID: 31542563 PMCID: PMC6908824 DOI: 10.1016/j.pep.2019.105501] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 12/02/2022]
Abstract
Bax is a pro-apoptosis protein that translocates from the cytosol to the mitochondria membrane upon initiation of programed cell death. Bax subsequently disrupts the mitochondria membrane, resulting in the release of cytochrome C which activates the downstream caspases. The structure of inactive Bax has been solved, but despite intensive investigation, the mechanism by which it regulates apoptosis is not established. The low yield of Bax expression in E. coli hampers efforts to elucidate the mechanism. Thus, we undertook a systematic study aimed at improving the yield of Bax. Bacteria were grown in a computer-controlled fermenter and expression was induced by addition of Isopropyl ß-D-1-thiogalactopyranoside (IPTG). The Bax expression level decreased continuously when the dissolved oxygen level was kept at 30%, which is non-limiting for E. coli. Alternatively, when oxygen input was decreased with constant agitation and air flow (or kLa), Bax yield increased by a factor of three. To make sure the short chain fatty acids generated during micro-aerobic fermentation had no adverse effect, their concentrations were closely monitored with HPLC and their effect on cell growth and Bax expression were investigated additionally using shake flasks. Through proteomic analysis using Tandem Mass Tag (TMT) labeling, we identified degradation pathway within E. coli cells as a potential player behind the lower expression level.
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Affiliation(s)
- Yi He
- National Institutes of Health, National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Bethesda, MD, 20892, USA.
| | - Yong Chen
- National Institutes of Health, National Heart, Lung and Blood Institute, Proteomics Core, Bethesda, MD, 20892, USA
| | - Daniel L Morris
- National Institutes of Health, National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Bethesda, MD, 20892, USA
| | - Duck-Yeon Lee
- National Institutes of Health, National Heart, Lung and Blood Institute, Biochemistry Core, Bethesda, MD, 20892, USA
| | - Nico Tjandra
- National Institutes of Health, National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Bethesda, MD, 20892, USA
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21
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健愉 冯, 玉山 朱, 陈 权, 凌 林, Jianyu F, Yushan Z, Quan C, Jialing L. [Physiological Function and Structural Basis of Bcl-2 Family Proteins]. ZHONGGUO XI BAO SHENG WU XUE XUE BAO 2019; 41:1477-1489. [PMID: 34249113 PMCID: PMC8265309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Apoptosis is an important biological process that plays a key role in the regulation of cell fate and homeostasis. The B-cell lymphoma-2 (Bcl-2) family proteins are important regulators of the apoptotic pathway, and their dysfunction is associated with a variety of diseases, including cancer, neurodegenerative and autoimmune diseases. In the past decade, a large number of research work on the physiological functions and atomic structures of Bcl-2 family proteins have been reported, which has deepened our understanding of the molecular mechanism and pathological significance of Bcl-2 family proteins. Recently, new drugs targeting different Bcl-2 proteins have been developed and used in clinics or tested in clinical trials. However, the complexity and diversity in functions and structures of Bcl-2 family have left many unsolved problems. This article summarizes current knowledge of the structure and function of Bcl-2 family proteins and discusses the pharmacological significance of Bcl-2 proteins as effective therapeutic targets.
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Affiliation(s)
| | | | | | - 林家 凌
- 俄克拉荷马大学健康科学中心生物化学与分子生物学系, 俄克拉何马城 73126-0901
| | - Feng Jianyu
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Zhu Yushan
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Chen Quan
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Lin Jialing
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma 73126, USA
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22
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sun H, Zhang C, Ma Y, Du M, Chen T. Controlling and online measurement of automatic dual-channel E-FRET microscope. Biomed Signal Process Control 2019. [DOI: 10.1016/j.bspc.2019.101585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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23
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Walensky LD. Targeting BAX to drug death directly. Nat Chem Biol 2019; 15:657-665. [PMID: 31209350 DOI: 10.1038/s41589-019-0306-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/10/2019] [Indexed: 02/07/2023]
Abstract
BCL-2 family protein interactions regulate apoptosis, a critical process that maintains tissue homeostasis but can cause a host of human diseases when deregulated. Venetoclax is the first FDA-approved drug to reactivate apoptosis in cancer by selectively targeting an anti-apoptotic BCL-2 family member. The drug's activity relies on an 'inhibit the inhibitor' mechanism, whereby blockade of a key surface groove on BCL-2 disables its capacity to neutralize pro-apoptotic effectors, such as BAX, a chief executioner protein of the apoptotic pathway. A series of physiologic and pharmacologic regulatory sites that mediate the activation or inhibition of BAX have recently been identified, providing blueprints for the development of alternative apoptosis modulators to block pathologic cell survival or avert unwanted cell death by drugging BAX directly.
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Affiliation(s)
- Loren D Walensky
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA. .,Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA, USA.
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24
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Kristiansson A, Ahlstedt J, Holmqvist B, Brinte A, Tran TA, Forssell-Aronsson E, Strand SE, Gram M, Åkerström B. Protection of Kidney Function with Human Antioxidation Protein α 1-Microglobulin in a Mouse 177Lu-DOTATATE Radiation Therapy Model. Antioxid Redox Signal 2019; 30:1746-1759. [PMID: 29943622 PMCID: PMC6477591 DOI: 10.1089/ars.2018.7517] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
AIMS Peptide receptor radionuclide therapy (PRRT) is in clinical use today to treat metastatic neuroendocrine tumors. Infused, radiolabeled, somatostatin analog peptides target tumors that are killed by irradiation damage. The peptides, however, are also retained in kidneys due to glomerular filtration, and the administered doses must be limited to avoid kidney damage. The human radical scavenger and antioxidant, α1-microglobulin (A1M), has previously been shown to protect bystander tissue against irradiation damage and has pharmacokinetic and biodistribution properties similar to somatostatin analogs. In this study, we have investigated if A1M can be used as a renal protective agent in PRRT. RESULTS We describe nephroprotective effects of human recombinant A1M on the short- and long-term renal damage observed following lutetium 177 (177Lu)-DOTATATE (150 MBq) exposure in BALB/c mice. After 1, 4, and 8 days (short term), 177Lu-DOTATATE injections resulted in increased formation of DNA double-strand breaks in the renal cortex, upregulated expression of apoptosis and stress response-related genes, and proteinuria (albumin in urine), all of which were significantly suppressed by coadministration of A1M (7 mg/kg). After 6, 12, and 24 weeks (long term), 177Lu-DOTATATE injections resulted in increased animal death, kidney lesions, glomerular loss, upregulation of stress genes, proteinuria, and plasma markers of reduced kidney function, all of which were suppressed by coadministration of A1M. Innovation and Conclusion: This study demonstrates that A1M effectively inhibits radiation-induced renal damage. The findings suggest that A1M may be used as a radioprotector during clinical PRRT, potentially facilitating improved tumor control and enabling more patients to receive treatment.
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Affiliation(s)
- Amanda Kristiansson
- 1 Division of Infection Medicine, Department of Clinical Sciences in Lund, Lund University , Lund, Sweden
| | - Jonas Ahlstedt
- 1 Division of Infection Medicine, Department of Clinical Sciences in Lund, Lund University , Lund, Sweden
| | | | | | - Thuy A Tran
- 3 Lund University Bioimaging Center , Lund, Sweden .,4 Department of Clinical Neuroscience, Karolinska Institutet , Stockholm, Sweden
| | - Eva Forssell-Aronsson
- 5 Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Cancer Center, University of Gothenburg , Sweden
| | - Sven-Erik Strand
- 6 Medical Radiation Physics, Department of Clinical Sciences in Lund, Lund University , Lund, Sweden
| | - Magnus Gram
- 1 Division of Infection Medicine, Department of Clinical Sciences in Lund, Lund University , Lund, Sweden .,7 Pediatrics, Department of Clinical Sciences in Lund, Skane University Hospital, Lund University , Lund, Sweden
| | - Bo Åkerström
- 1 Division of Infection Medicine, Department of Clinical Sciences in Lund, Lund University , Lund, Sweden
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25
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Dengler MA, Robin AY, Gibson L, Li MX, Sandow JJ, Iyer S, Webb AI, Westphal D, Dewson G, Adams JM. BAX Activation: Mutations Near Its Proposed Non-canonical BH3 Binding Site Reveal Allosteric Changes Controlling Mitochondrial Association. Cell Rep 2019; 27:359-373.e6. [DOI: 10.1016/j.celrep.2019.03.040] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 02/13/2019] [Accepted: 03/12/2019] [Indexed: 12/26/2022] Open
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26
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Abstract
BCL-2 family proteins interact in a network that regulates apoptosis. The BH3 amino acid sequence motif serves to bind together this conglomerate protein family, both literally and figuratively. BH3 motifs are present in antiapoptotic and proapoptotic BCL-2 homologs, and in a separate group of unrelated BH3-only proteins often appended to the BCL-2 family. BH3-containing helices mediate many of their physical interactions to determine cell death versus survival, leading to the development of BH3 mimetics as therapeutics. Here we provide an overview of BCL-2 family interactions, their relevance in health and disease, and the progress toward regulating their interactions therapeutically.
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Affiliation(s)
- Jason D Huska
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Heather M Lamb
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - J Marie Hardwick
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
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27
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Li SZ, Ren JW, Fei J, Zhang XD, Du RL. Cordycepin induces Bax‑dependent apoptosis in colorectal cancer cells. Mol Med Rep 2018; 19:901-908. [PMID: 30535479 PMCID: PMC6323220 DOI: 10.3892/mmr.2018.9717] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 10/25/2018] [Indexed: 01/25/2023] Open
Abstract
Cordycepin, or 3′-deoxyadenosine, is a derivative of the nucleoside adenosine. Initially extracted from the fungus Cordyceps militaris, cordycepin exhibits antitumor activity against certain cancer cell lines; however, the mechanism by which cordycepin counteracts colorectal cancer (CRC) remains poorly understood. The aim of the present study was to explore the underlying mechanisms of cordycepin against human CRC. To investigate the molecular mechanisms of cordycepin against colon cancer and in driving apoptosis, p53 and Bcl-2-like protein 4-null (Bax−/−) colon cancer HCT116 cell lines were used. Cell viability and growth were repressed in a dose-dependent manner in cells treated with cordycepin. Treatment with cordycepin resulted in increased apoptosis in HCT116 cells; however, flow cytometic analysis demonstrated that apoptosis was notably decreased in the Bax−/− HCT116 cell lines, but not in the p53−/− HCT116 cell lines. Furthermore, cordycepin exposure resulted in the translocation of Bax from the cytosol to the mitochondria and the subsequent release of cytochrome c from the mitochondria. Results from the present study demonstrated that cordycepin inhibited colon cancer cell growth in vitro and this appears to be through the endogenous Bax-dependent mitochondrial apoptosis pathway, which suggested a molecular mechanism for cordycepin against human colon cancer. These results indicated the possibility of cordycepin as a novel drug for the prevention of colon cancer.
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Affiliation(s)
- Shang-Ze Li
- Medical Science Research Center, Zhongnan Hospital of Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Jian-Wei Ren
- Tibet University Medical College, Lhasa, Tibet 850000, P.R. China
| | - Jing Fei
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Xiao-Dong Zhang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Run-Lei Du
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P.R. China
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28
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Topology of active, membrane-embedded Bax in the context of a toroidal pore. Cell Death Differ 2018; 25:1717-1731. [PMID: 30185826 DOI: 10.1038/s41418-018-0184-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/20/2018] [Accepted: 05/21/2018] [Indexed: 01/18/2023] Open
Abstract
Bax is a Bcl-2 protein critical for apoptosis induction. In healthy cells, Bax is mostly a monomeric, cytosolic protein, while upon apoptosis initiation it inserts into the outer mitochondrial membrane, oligomerizes, and forms pores that release proapoptotic factors like Cytochrome c into the cytosol. The structures of active Bax and its homolog Bak are only partially understood and the topology of the proteins with respect to the membrane bilayer is controversially described in the literature. Here, we systematically review and examine the protein-membrane, protein-water, and protein-protein contacts of the nine helices of active Bax and Bak, and add a new set of topology data obtained by fluorescence and EPR methods. We conclude based on the consistent part of the datasets that the core/dimerization domain of Bax (Bak) is water exposed with only helices 4 and 5 in membrane contact, whereas the piercing/latch domain is in peripheral membrane contact, with helix 9 being transmembrane. Among the available structural models, those considering the dimerization/core domain at the rim of a toroidal pore are the most plausible to describe the active state of the proteins, although the structural flexibility of the piercing/latch domain does not allow unambiguous discrimination between the existing models.
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29
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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] [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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30
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Ekanayake V, Nisan D, Ryzhov P, Yao Y, Marassi FM. Lipoprotein Particle Formation by Proapoptotic tBid. Biophys J 2018; 115:533-542. [PMID: 30017071 DOI: 10.1016/j.bpj.2018.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/13/2018] [Accepted: 06/19/2018] [Indexed: 10/28/2022] Open
Abstract
The interactions of Bcl-2 family proteins with intracellular lipids are essential for the regulation of apoptosis, a mechanism of programmed cell death that is central to the health and development of multicellular organisms. Bid and its caspase-8 cleavage product, tBid, promote the permeabilization of the mitochondrial outer membrane and sequester antiapoptotic Bcl-2 proteins to counter their cytoprotective activity. Bid and tBid also promote lipid exchange, a characteristic trait of apoptosis. Here, we show that tBid is capable of associating with phospholipids to form soluble, nanometer-sized lipoprotein particles that retain binding affinity for the antiapoptotic protein Bcl-xL. The tBid lipoprotein particles form with a lipid/protein stoichiometry in the range of 20/1 and have a diameter of ∼11.5 nm. Lipoparticle-bound tBid retains an α-helical structure and binds Bcl-xL through its third Bcl-2 homology motif, forming a soluble, lipid-associated heteroprotein complex. The results shed light on the role of lipids in mediating Bcl-2 protein mobility and interactions.
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Affiliation(s)
- Vindana Ekanayake
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Danielle Nisan
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Pavel Ryzhov
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Yong Yao
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Francesca M Marassi
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California.
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31
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Ma ZW, Liu DX. Humanin decreases mitochondrial membrane permeability by inhibiting the membrane association and oligomerization of Bax and Bid proteins. Acta Pharmacol Sin 2018; 39:1012-1021. [PMID: 29265109 DOI: 10.1038/aps.2017.169] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 10/18/2017] [Indexed: 12/13/2022] Open
Abstract
Humanin (HN) is a 24-residue peptide identified from the brain of a patient with Alzheimer's disease (AD). HN has been found to protect against neuronal insult caused by Aβ peptides or transfection of familial AD mutant genes. In order to elucidate the molecular mechanisms of HN neuroprotection, we explored the effects of HN on the association of Bax or Bid with lipid bilayers and their oligomerization in the membrane. By using single-molecule fluorescence and Förster resonance energy transfer techniques, we showed that Bax was mainly present as monomers, dimers and tetramers in lipid bilayers, while truncated Bid (tBid) enhanced the membrane association and tetramerization of Bax. HN (100 nmol/L) inhibited the self-association and tBid-activated association of Bax with the bilayers, and significantly decreased the proportion of Bax in tetramers. Furthermore, HN inhibited Bid translocation to lipid bilayers. HN could bind with Bax and Bid either in solution or in the membrane. However, HN could not pull the proteins out of the membrane. Based on these results, we propose that HN binds to Bax and cBid in solution and inhibits their translocation to the membrane. Meanwhile, HN interacts with the membrane-bound Bax and tBid, preventing the recruitment of cytosolic Bax and its oligomerization in the membrane. In this way, HN inhibits Bax pore formation in mitochondrial outer membrane and suppresses cytochrome c release and mitochondria-dependent apoptosis.
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32
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Edlich F. BCL-2 proteins and apoptosis: Recent insights and unknowns. Biochem Biophys Res Commun 2018; 500:26-34. [DOI: 10.1016/j.bbrc.2017.06.190] [Citation(s) in RCA: 233] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/30/2017] [Indexed: 01/08/2023]
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33
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Uren RT, Iyer S, Kluck RM. Pore formation by dimeric Bak and Bax: an unusual pore? Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630157 DOI: 10.1098/rstb.2016.0218] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Apoptotic cell death via the mitochondrial pathway occurs in all vertebrate cells and requires the formation of pores in the mitochondrial outer membrane. Two Bcl-2 protein family members, Bak and Bax, form these pores during apoptosis, and how they do so has been investigated for the last two decades. Many of the conformation changes that occur during their transition to pore-forming proteins have now been delineated. Notably, biochemical, biophysical and structural studies indicate that symmetric homodimers are the basic unit of pore formation. Each dimer contains an extended hydrophobic surface that lies on the outer membrane, and is anchored at either end by a transmembrane domain. Membrane-remodelling events such as positive membrane curvature have been reported to accompany apoptotic pore formation, suggesting Bak and Bax form lipidic pores rather than proteinaceous pores. However, it remains unclear how symmetric dimers assemble to porate the membrane. Here, we review how clusters of dimers and their lipid-mediated interactions provide a molecular explanation for the heterogeneous assemblies of Bak and Bax observed during apoptosis.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Rachel T Uren
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Sweta Iyer
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Ruth M Kluck
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia .,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
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34
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Transmembrane TNF-alpha promotes chemoresistance in breast cancer cells. Oncogene 2018; 37:3456-3470. [PMID: 29559745 PMCID: PMC6013421 DOI: 10.1038/s41388-018-0221-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 02/10/2018] [Accepted: 02/25/2018] [Indexed: 12/22/2022]
Abstract
Chemoresistance remains a major obstacle to successful treatment of breast cancer. Although soluble tumor necrosis factor-α (sTNF-α) has been implicated in mediating drug-resistance in human cancers, whether transmembrane tumor necrosis factor-α (tmTNF-α) plays a role in chemoresistance remains unclear. Here we found that over 50% of studied patients expressed tmTNF-α at high levels in breast cancer tissues and tmTNF-α expression positively correlated with resistance to anthracycline chemotherapy. Alteration of tmTNF-α expression changed the sensitivity of primary human breast cancer cells and breast cancer cell lines to doxorubicin (DOX). Overexpression of N-terminal fragment (NTF) of tmTNF-α, a mutant form with intact intracellular domain of tmTNF-α to transmit reverse signals, induced DOX-resistance. Mechanistically, the tmTNF-α/NTF-ERK-GST-π axis and tmTNF-α/NTF-NF-κB-mediated anti-apoptotic functions were required for tmTNF-α-induced DOX-resistance. In a xenograft mouse model, the combination of tmTNF-α suppression with chemotherapy significantly enhanced the efficacy of DOX. Our data indicate that tmTNF-α mediates DOX-resistance through reverse signaling and targeting tmTNF-α may be beneficial for the treatment of DOX-resistant breast cancer.
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35
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Lin F, Du M, Yang F, Wei L, Chen T. Improved spectrometer-microscope for quantitative fluorescence resonance energy transfer measurement based on simultaneous spectral unmixing of excitation and emission spectra. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-10. [PMID: 29313324 DOI: 10.1117/1.jbo.23.1.016006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 12/07/2017] [Indexed: 06/07/2023]
Abstract
Based on our recently developed quantitative fluorescence resonance energy transfer (FRET) measurement method using simultaneous spectral unmixing of excitation and emission spectra (ExEm-spFRET), we here set up an improved spectrometer-microscope (SM) for implementing modified ExEm-spFRET (mExEm-spFRET), in which a system correction factor (fsc) is introduced. Our SM system is very stable for at least six months. Implementation of mExEm-spFRET with four or two excitation wavelengths on SM for single living cells expressing different FRET constructs obtained consistent FRET efficiency (E) and acceptor-donor concentration ratio (Rc) values. We also performed mExEm-spFRET measurement for single living cells coexpressing cyan fluorescent protein (CFP)-Bax and yellow fluorescent protein (YFP)-Bax and found that the E values between CFP-Bax and YFP-Bax were very low (2.2%) and independent of Rc for control cells, indicating that Bax did not exist as homooligomer in healthy cells, but positively proportional to Rc in the case of Rc<1 and kept constant value (25%) when Rc>1 for staurosporine (STS)-treated cells, demonstrating that all Bax formed homooligomer after STS treatment for 6 h.
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Affiliation(s)
- Fangrui Lin
- South China Normal University, MOE Key Laboratory of Laser Life Science and College of Life Science,, China
| | - Mengyan Du
- South China Normal University, MOE Key Laboratory of Laser Life Science and College of Life Science,, China
| | - Fangfang Yang
- South China Normal University, MOE Key Laboratory of Laser Life Science and College of Life Science,, China
| | - Lichun Wei
- South China Normal University, MOE Key Laboratory of Laser Life Science and College of Life Science,, China
| | - Tongsheng Chen
- South China Normal University, MOE Key Laboratory of Laser Life Science and College of Life Science,, China
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36
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Zhang JJ, Zhu Y, Yang C, Liu X, Peng YP, Jiang KR, Miao Y, Xu ZK. Yin Yang-1 increases apoptosis through Bax activation in pancreatic cancer cells. Oncotarget 2017; 7:28498-509. [PMID: 27074573 PMCID: PMC5053741 DOI: 10.18632/oncotarget.8654] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 03/28/2016] [Indexed: 01/05/2023] Open
Abstract
The transcriptional regulator Yin Yang-1 (YY1) is a tumor suppressor known to be overexpressed in pancreatic cancer. We found that overexpression of YY1 promoted apoptosis and increased the expression and mitochondrial localization of the pro-apoptotic Bax protein in pancreatic cancer cell lines. Luciferase reporter, electrophoretic mobility shift (EMSA), and chromatin immunoprecipitation (ChIP) assays revealed binding of YY1 to the BAX promoter. Moreover, YY1 promoted pancreatic cancer cell apoptosis through Bax transcriptional activation and subsequent translocation of Bax to the mitochondrial membrane, leading to cytochrome c release, and caspase activation.YY1 and BAX are co-expressed in pancreatic cancer tissues and higher BAX expression predicts better outcomes for patients. The ability of YY1 to promote apoptosis in pancreatic cancer cells suggests it may represent a valuable diagnostic and therapeutic target.
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Affiliation(s)
- Jing-Jing Zhang
- Pancreas Institute of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
| | - Yi Zhu
- Pancreas Institute of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
| | - Chuang Yang
- Pancreas Institute of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
| | - Xian Liu
- Pancreas Institute of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
| | - Yun-Peng Peng
- Pancreas Institute of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
| | - Kui-Rong Jiang
- Pancreas Institute of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
| | - Yi Miao
- Pancreas Institute of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China.,Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
| | - Ze-Kuan Xu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, People's Republic of China
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37
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Membrane insertion of the BAX core, but not latch domain, drives apoptotic pore formation. Sci Rep 2017; 7:16259. [PMID: 29176554 PMCID: PMC5701199 DOI: 10.1038/s41598-017-16384-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 10/31/2017] [Indexed: 12/31/2022] Open
Abstract
Despite intensive research effort, how the paradigmatic proapoptotic protein BAX forms lethal apoptotic pores at the mitochondrial outer membrane (MOM) remains incompletely understood. Here, we used biophysical tools and minimalist model systems to identify the specific regions in BAX driving apoptotic pore formation, and to gain more insight into underlying mechanisms. Fluorescence mapping revealed that fully active BAX adopts a BH3-in-groove dimeric conformation in MOM-like membranes, with BAX α4-α5 helices belonging to its core domain inserting deeper into the membrane lipid bilayer than BAX α6-α8 helices belonging to its latch domain. In our reconstituted systems, antiapoptotic BCLXL formed canonical heterodimeric BH3-in-groove complexes with BAX, and blocked membrane insertion of BAX core α4-α5 helices, but not BAX latch α6-α8 helices. Moreover, poly(ethylene glycol) (PEG) conjugation (PEGylation) at multiple individual sites along the BAX core, but not latch domain, potently inhibited BAX pore-forming activity. Additional combined computational and experimental evidence revealed that the BAX core α5 helix displays a bilayer-destabilizing membrane interaction mode that is absent in BAX latch α6-α8 helices. Based on this collective set of evidence, we propose that membrane insertion of the BAX core, but not latch domain, is critical for BAX apoptotic pore formation.
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38
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Peña‐Blanco A, García‐Sáez AJ. Bax, Bak and beyond — mitochondrial performance in apoptosis. FEBS J 2017; 285:416-431. [DOI: 10.1111/febs.14186] [Citation(s) in RCA: 340] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/12/2017] [Accepted: 07/26/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Aida Peña‐Blanco
- Interfaculty Institute of Biochemistry Tübingen University Germany
| | - Ana J. García‐Sáez
- Interfaculty Institute of Biochemistry Tübingen University Germany
- Max‐Planck Institute for Intelligent Systems Stuttgart Germany
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39
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Dingeldein APG, Pokorná Š, Lidman M, Sparrman T, Šachl R, Hof M, Gröbner G. Apoptotic Bax at Oxidatively Stressed Mitochondrial Membranes: Lipid Dynamics and Permeabilization. Biophys J 2017; 112:2147-2158. [PMID: 28538152 DOI: 10.1016/j.bpj.2017.04.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 02/23/2017] [Accepted: 04/05/2017] [Indexed: 12/20/2022] Open
Abstract
Mitochondria are crucial compartments of eukaryotic cells because they function as the cellular power plant and play a central role in the early stages of programmed cell death (apoptosis). To avoid undesired cell death, this apoptotic pathway is tightly regulated by members of the Bcl-2 protein family, which interact on the external surface of the mitochondria, i.e., the mitochondrial outer membrane (MOM), and modulate its permeability to apoptotic factors, controlling their release into the cytosol. A growing body of evidence suggests that the MOM lipids play active roles in this permeabilization process. In particular, oxidized phospholipids (OxPls) formed under intracellular stress seem to directly induce apoptotic activity at the MOM. Here we show that the process of MOM pore formation is sensitive to the type of OxPls species that are generated. We created MOM-mimicking liposome systems, which resemble the cellular situation before apoptosis and upon triggering of oxidative stress conditions. These vesicles were studied using 31P solid-state magic-angle-spinning nuclear magnetic resonance spectroscopy and differential scanning calorimetry, together with dye leakage assays. Direct polarization and cross-polarization nuclear magnetic resonance experiments enabled us to probe the heterogeneity of these membranes and their associated molecular dynamics. The addition of apoptotic Bax protein to OxPls-containing vesicles drastically changed the membranes' dynamic behavior, almost completely negating the previously observed effect of temperature on the lipids' molecular dynamics and inducing an ordering effect that led to more cooperative membrane melting. Our results support the hypothesis that the mitochondrion-specific lipid cardiolipin functions as a first contact site for Bax during its translocation to the MOM in the onset of apoptosis. In addition, dye leakage assays revealed that different OxPls species in the MOM-mimicking vesicles can have opposing effects on Bax pore formation.
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Affiliation(s)
| | - Šárka Pokorná
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Lidman
- Department of Chemistry, Umeå University, Umeå, Sweden
| | | | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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40
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Conformational Heterogeneity in the Activation Mechanism of Bax. Structure 2017; 25:1310-1316.e3. [PMID: 28712810 DOI: 10.1016/j.str.2017.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/05/2017] [Accepted: 06/16/2017] [Indexed: 01/02/2023]
Abstract
Bax is known for its pro-apoptotic role within the mitochondrial pathway of apoptosis. However, the mechanism for transitioning Bax from cytosolic to membrane-bound oligomer remains elusive. Previous nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) studies defined monomeric Bax as conformationally homogeneous. Yet it has recently been proposed that monomeric Bax exists in equilibrium with a minor state that is distinctly different from its NMR structure. Here, we revisited the structural analysis of Bax using methods uniquely suited for unveiling "invisible" states of proteins, namely, NMR paramagnetic relaxation enhancements and EPR double electron-electron resonance (DEER). Additionally we examined the effect of glycerol, the co-solvent of choice in DEER studies, on the structure of Bax using NMR chemical-shift perturbations and residual dipolar couplings. Based on our combined NMR and EPR results, Bax is a conformationally homogeneous protein prior to its activation.
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41
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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] [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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42
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Bax transmembrane domain interacts with prosurvival Bcl-2 proteins in biological membranes. Proc Natl Acad Sci U S A 2016; 114:310-315. [PMID: 28028215 DOI: 10.1073/pnas.1612322114] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [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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43
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Cosentino K, García-Sáez AJ. Bax and Bak Pores: Are We Closing the Circle? Trends Cell Biol 2016; 27:266-275. [PMID: 27932064 DOI: 10.1016/j.tcb.2016.11.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/28/2016] [Accepted: 11/07/2016] [Indexed: 01/19/2023]
Abstract
Bax and its homolog Bak are key regulators of the mitochondrial pathway of apoptosis. On cell stress Bax and Bak accumulate at distinct foci on the mitochondrial surface where they undergo a conformational change, oligomerize, and mediate cytochrome c release, leading to cell death. The molecular mechanisms of Bax and Bak assembly and mitochondrial permeabilization have remained a longstanding question in the field. Recent structural and biophysical studies at several length scales have shed light on key aspects of Bax and Bak function that have shifted how we think this process occurs. These discoveries reveal an unexpected molecular mechanism in which Bax (and likely Bak) dimers assemble into oligomers with an even number of molecules that fully or partially delineate pores of different sizes to permeabilize the mitochondrial outer membrane (MOM) during apoptosis.
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany; Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, Stuttgart, Germany.
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44
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Gahl RF, Dwivedi P, Tjandra N. Bcl-2 proteins bid and bax form a network to permeabilize the mitochondria at the onset of apoptosis. Cell Death Dis 2016; 7:e2424. [PMID: 27763642 PMCID: PMC5133987 DOI: 10.1038/cddis.2016.320] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/23/2016] [Accepted: 09/05/2016] [Indexed: 12/23/2022]
Abstract
The most critical step in the initiation of apoptosis is the activation of the Bcl-2 family of proteins to oligomerize and permeabilize the outer-mitochondrial membrane (OMM). As this step results in the irreversible release of factors that enhance cellular degradation, it is the point of no return in programmed cell death and would be an ideal therapeutic target. However, the arrangement of the Bcl-2 proteins in the OMM during permeabilization still remains unknown. It is also unclear whether the Bcl-2 protein, Bid, directly participates in the formation of the oligomers in live cells, even though it is cleaved and translocates to the OMM at the initiation of apoptosis. Therefore, we utilized confocal microscopy to measure Förster resonance energy transfer (FRET) efficiencies in live cells to determine the conformation(s) and intermolecular contacts of Bid within these Bcl-2 oligomers. We found that Bid adopts an extended conformation, which appears to be critical for its association with the mitochondrial membrane. This conformation is also important for intermolecular contacts within the Bid oligomer. More importantly for the first time, direct intermolecular contacts between Bid and Bax were observed, thereby, confirming Bid as a key component of these oligomers. Furthermore, the observed FRET efficiencies allowed us to propose an oligomeric arrangement of Bid, Bax, and possibly other members of the Bcl-2 family of proteins that form a self-propagating network that permeabilizes the OMM.
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Affiliation(s)
- Robert F Gahl
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda 20892, MD, USA
| | - Pallavi Dwivedi
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda 20892, MD, USA
| | - Nico Tjandra
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda 20892, MD, USA
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45
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Wang P, Wang P, Liu B, Zhao J, Pang Q, Agrawal SG, Jia L, Liu FT. Dynamin-related protein Drp1 is required for Bax translocation to mitochondria in response to irradiation-induced apoptosis. Oncotarget 2016; 6:22598-612. [PMID: 26093086 PMCID: PMC4673185 DOI: 10.18632/oncotarget.4200] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/21/2015] [Indexed: 01/02/2023] Open
Abstract
Translocation of the pro-apoptotic protein Bax from the cytosol to the mitochondria is a crucial step in DNA damage-mediated apoptosis, and is also found to be involved in mitochondrial fragmentation. Irradiation-induced cytochrome c release and apoptosis was associated with Bax activation, but not mitochondrial fragmentation. Both Bax and Drp1 translocated from the cytosol to the mitochondria in response to irradiation. However, Drp1 mitochondrial translocation and oligomerization did not require Bax, and failed to induce apoptosis in Bax deficient diffuse large B-cell lymphoma (DLBCL) cells. Using fluorescent microscopy and the intensity correlation analysis, we demonstrated that Bax and Drp1 were colocalized and the levels of colocalization were increased by UV irradiation. Using co-immuno-precipitation, we confirmed that Bax and Drp1 were binding partners. Irradiation induced a time-associated increase in the interaction between active Bax and Drp1. Knocking down Drp1 using siRNA blocked UV irradiation-mediated Bax mitochondrial translocation. In conclusion, our findings demonstrate for the first time, that Drp1 is required for Bax mitochondrial translocation, but Drp1-induced mitochondrial fragmentation alone is not sufficient to induce apoptosis in DLBCL cells.
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Affiliation(s)
- Ping Wang
- Department of Radiobiology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Centre of Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Peiguo Wang
- Department of Radiobiology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Centre of Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Becky Liu
- East Surrey Hospital, Surrey and Sussex Healthcare NHS Trust, Redhill, Surrey, United Kingdom
| | - Jing Zhao
- Department of Radiobiology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Centre of Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Qingsong Pang
- Department of Radiobiology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Centre of Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Samir G Agrawal
- Pathology Group, Blizard Institute, Queen Mary University of London, London, United Kingdom
| | - Li Jia
- Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Feng-Ting Liu
- Department of Radiobiology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Centre of Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
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46
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Zhang M, Zheng J, Nussinov R, Ma B. Oncogenic Mutations Differentially Affect Bax Monomer, Dimer, and Oligomeric Pore Formation in the Membrane. Sci Rep 2016; 6:33340. [PMID: 27630059 PMCID: PMC5024136 DOI: 10.1038/srep33340] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 08/25/2016] [Indexed: 12/20/2022] Open
Abstract
Dysfunction of Bax, a pro-apoptotic regulator of cellular metabolism is implicated in neurodegenerative diseases and cancer. We have constructed the first atomistic models of the Bax oligomeric pore consisting with experimental residue-residue distances. The models are stable, capturing well double electron-electron resonance (DEER) spectroscopy measurements and provide structural details in line with the DEER data. Comparison with the latest experimental results revealed that our models agree well with both Bax and Bak pores, pointed to a converged structural arrangement for Bax and Bak pore formation. Using multi-scale molecular dynamics simulations, we probed mutational effects on Bax transformation from monomer → dimer → membrane pore formation at atomic resolution. We observe that two cancer-related mutations, G40E and S118I, allosterically destabilize the monomer and stabilize an off-pathway swapped dimer, preventing productive pore formation. This observation suggests a mechanism whereby the mutations may work mainly by over-stabilizing the monomer → dimer transformation toward an unproductive off-pathway swapped-dimer state. Our observations point to misfolded Bax states, shedding light on the molecular mechanism of Bax mutation-elicited cancer. Most importantly, the structure of the Bax pore facilitates future study of releases cytochrome C in atomic detail.
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Affiliation(s)
- Mingzhen Zhang
- Department of Chemical & Biomolecular Engineering, the University of Akron, Akron, Ohio 44325
| | - Jie Zheng
- Department of Chemical & Biomolecular Engineering, the University of Akron, Akron, Ohio 44325
| | - 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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47
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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] [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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48
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Conformational Heterogeneity of Bax Helix 9 Dimer for Apoptotic Pore Formation. Sci Rep 2016; 6:29502. [PMID: 27381287 PMCID: PMC4933972 DOI: 10.1038/srep29502] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [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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49
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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] [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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50
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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] [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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