1
|
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 PMCID: PMC11346437 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.
Collapse
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
| |
Collapse
|
2
|
Gitego N, Agianian B, Mak OW, Kumar Mv V, Cheng EH, Gavathiotis E. Chemical modulation of cytosolic BAX homodimer potentiates BAX activation and apoptosis. Nat Commun 2023; 14:8381. [PMID: 38104127 PMCID: PMC10725471 DOI: 10.1038/s41467-023-44084-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 11/29/2023] [Indexed: 12/19/2023] Open
Abstract
The BCL-2 family protein BAX is a major regulator of physiological and pathological cell death. BAX predominantly resides in the cytosol in a quiescent state and upon stress, it undergoes conformational activation and mitochondrial translocation leading to mitochondrial outer membrane permeabilization, a critical event in apoptosis execution. Previous studies reported two inactive conformations of cytosolic BAX, a monomer and a dimer, however, it remains unclear how they regulate BAX. Here we show that, surprisingly, cancer cell lines express cytosolic inactive BAX dimers and/or monomers. Expression of inactive dimers, results in reduced BAX activation, translocation and apoptosis upon pro-apoptotic drug treatments. Using the inactive BAX dimer structure and a pharmacophore-based drug screen, we identify a small-molecule modulator, BDM19 that binds and activates cytosolic BAX dimers and prompts cells to apoptosis either alone or in combination with BCL-2/BCL-XL inhibitor Navitoclax. Our findings underscore the role of the cytosolic inactive BAX dimer in resistance to apoptosis and demonstrate a strategy to potentiate BAX-mediated apoptosis.
Collapse
Affiliation(s)
- Nadege Gitego
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
- Montefiore Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Bogos Agianian
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
- Montefiore Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Oi Wei Mak
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
- Montefiore Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Vasantha Kumar Mv
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
- Montefiore Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Emily H Cheng
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Weill Cornell Medicine, New York, NY, USA
| | - Evripidis Gavathiotis
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA.
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
- Montefiore Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA.
| |
Collapse
|
3
|
Moujalled DM, Brown FC, Chua CC, Dengler MA, Pomilio G, Anstee NS, Litalien V, Thompson E, Morley T, MacRaild S, Tiong IS, Morris R, Dun K, Zordan A, Shah J, Banquet S, Halilovic E, Morris E, Herold MJ, Lessene G, Adams JM, Huang DCS, Roberts AW, Blombery P, Wei AH. Acquired mutations in BAX confer resistance to BH3-mimetic therapy in acute myeloid leukemia. Blood 2023; 141:634-644. [PMID: 36219880 PMCID: PMC10651776 DOI: 10.1182/blood.2022016090] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 08/18/2022] [Accepted: 09/19/2022] [Indexed: 11/20/2022] Open
Abstract
Randomized trials in acute myeloid leukemia (AML) have demonstrated improved survival by the BCL-2 inhibitor venetoclax combined with azacitidine in older patients, and clinical trials are actively exploring the role of venetoclax in combination with intensive chemotherapy in fitter patients with AML. As most patients still develop recurrent disease, improved understanding of relapse mechanisms is needed. We find that 17% of patients relapsing after venetoclax-based therapy for AML have acquired inactivating missense or frameshift/nonsense mutations in the apoptosis effector gene BAX. In contrast, such variants were rare after genotoxic chemotherapy. BAX variants arose within either leukemic or preleukemic compartments, with multiple mutations observed in some patients. In vitro, AML cells with mutated BAX were competitively selected during prolonged exposure to BCL-2 antagonists. In model systems, AML cells rendered deficient for BAX, but not its close relative BAK, displayed resistance to BCL-2 targeting, whereas sensitivity to conventional chemotherapy was variable. Acquired mutations in BAX during venetoclax-based therapy represent a novel mechanism of resistance to BH3-mimetics and a potential barrier to the long-term efficacy of drugs targeting BCL-2 in AML.
Collapse
Affiliation(s)
- Donia M. Moujalled
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Fiona C. Brown
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Chong Chyn Chua
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Michael A. Dengler
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Division of Oncology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia
| | - Giovanna Pomilio
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Natasha S. Anstee
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Veronique Litalien
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | | | - Thomas Morley
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Sarah MacRaild
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Ing S. Tiong
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Department of Pathology, Peter MacCallum Cancer Centre and Royal Melbourne Hospital, Melbourne, Australia
| | - Rhiannon Morris
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Karen Dun
- Victorian Cancer and Cytogenetics Service, St. Vincent’s Hospital, Melbourne, Fitzroy, Australia
| | - Adrian Zordan
- Victorian Cancer and Cytogenetics Service, St. Vincent’s Hospital, Melbourne, Fitzroy, Australia
| | - Jaynish Shah
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
| | - Sebastien Banquet
- Oncology Research and Development Unit, Institut de Recherches International Servier, Paris, France
| | - Ensar Halilovic
- Novartis Institutes for BioMedical Research, Novartis, Cambridge, MA
| | - Erick Morris
- Novartis Institutes for BioMedical Research, Novartis, Cambridge, MA
| | - Marco J. Herold
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - Guillaume Lessene
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - Jerry M. Adams
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - David C. S. Huang
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - Andrew W. Roberts
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- The University of Melbourne, Melbourne, Australia
- Department of Clinical Haematology, Peter MacCallum Cancer Centre and Royal Melbourne Hospital, Melbourne, Australia
| | | | - Andrew H. Wei
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Department of Clinical Haematology, The Alfred, Melbourne, Australia
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- The University of Melbourne, Melbourne, Australia
- Department of Clinical Haematology, Peter MacCallum Cancer Centre and Royal Melbourne Hospital, Melbourne, Australia
| |
Collapse
|
4
|
Kim WJ, Abdel-Wahab O. Acquired BAX mutations in AML. Blood 2023; 141:562-564. [PMID: 36757728 PMCID: PMC9936327 DOI: 10.1182/blood.2022018508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
|
5
|
Rouchidane Eyitayo A, Giraud MF, Daury L, Lambert O, Gonzalez C, Manon S. Cell-free synthesis and reconstitution of Bax in nanodiscs: Comparison between wild-type Bax and a constitutively active mutant. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184075. [PMID: 36273540 DOI: 10.1016/j.bbamem.2022.184075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/11/2022] [Accepted: 10/16/2022] [Indexed: 11/06/2022]
Abstract
Bax is a major player in the mitochondrial pathway of apoptosis, by making the Outer Mitochondrial Membrane (OMM) permeable to various apoptogenic factors, including cytochrome c. In order to get further insight into the structure and function of Bax when it is inserted in the OMM, we attempted to reconstitute Bax in nanodiscs. Cell-free protein synthesis in the presence of nanodiscs did not yield Bax-containing nanodiscs, but it provided a simple way to purify full-length Bax without any tag. Purified wild-type Bax (BaxWT) and a constitutively active mutant (BaxP168A) displayed biochemical properties that were in line with previous characterizations following their expression in yeast and human cells followed by their reconstitution into liposomes. Both Bax variants were then reconstituted in nanodiscs. Size exclusion chromatography, dynamic light scattering and transmission electron microscopy showed that nanodiscs formed with BaxP168A were larger than nanodiscs formed with BaxWT. This was consistent with the hypothesis that BaxP168A was reconstituted in nanodiscs as an active oligomer.
Collapse
Affiliation(s)
| | - Marie-France Giraud
- IBGC, UMR5095, CNRS, Université de Bordeaux, France; CBMN, UMR5248, CNRS, Université de Bordeaux, France
| | | | | | | | - Stéphen Manon
- IBGC, UMR5095, CNRS, Université de Bordeaux, France.
| |
Collapse
|
6
|
Pore-forming proteins as drivers of membrane permeabilization in cell death pathways. Nat Rev Mol Cell Biol 2022; 24:312-333. [PMID: 36543934 DOI: 10.1038/s41580-022-00564-w] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2022] [Indexed: 12/24/2022]
Abstract
Regulated cell death (RCD) relies on activation and recruitment of pore-forming proteins (PFPs) that function as executioners of specific cell death pathways: apoptosis regulator BAX (BAX), BCL-2 homologous antagonist/killer (BAK) and BCL-2-related ovarian killer protein (BOK) for apoptosis, gasdermins (GSDMs) for pyroptosis and mixed lineage kinase domain-like protein (MLKL) for necroptosis. Inactive precursors of PFPs are converted into pore-forming entities through activation, membrane recruitment, membrane insertion and oligomerization. These mechanisms involve protein-protein and protein-lipid interactions, proteolytic processing and phosphorylation. In this Review, we discuss the structural rearrangements incurred by RCD-related PFPs and describe the mechanisms that manifest conversion from autoinhibited to membrane-embedded molecular states. We further discuss the formation and maturation of membrane pores formed by BAX/BAK/BOK, GSDMs and MLKL, leading to diverse pore architectures. Lastly, we highlight commonalities and differences of PFP mechanisms involving BAX/BAK/BOK, GSDMs and MLKL and conclude with a discussion on how, in a population of challenged cells, the coexistence of cell death modalities may have profound physiological and pathophysiological implications.
Collapse
|
7
|
Gelles JD, Mohammed JN, Chen Y, Sebastian TM, Chipuk JE. A kinetic fluorescence polarization ligand assay for monitoring BAX early activation. CELL REPORTS METHODS 2022; 2:100174. [PMID: 35419554 PMCID: PMC9004659 DOI: 10.1016/j.crmeth.2022.100174] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 12/20/2021] [Accepted: 02/02/2022] [Indexed: 12/23/2022]
Abstract
Developmental, homeostatic, and pharmacological pro-apoptotic signals converge by activating the BCL-2 family member BAX. Studies investigating molecular regulation of BAX are commonly limited to methodologies measuring endpoint phenotypes and do not assess activation of monomeric BAX. Here, we present FLAMBE, a fluorescence polarization ligand assay for monitoring BAX early activation, that measures activation-induced release of a peptide probe in real time. Using complementary parallel and tandem biochemical techniques, we validate, corroborate, and apply FLAMBE to a contemporary repertoire of BAX modulators, characterizing their contributions within the early steps of BAX activation. Additionally, we use FLAMBE to reveal that historically "dead" BAX mutants remain responsive to activation as quasi-functional monomers. We also identify data metrics for comparative analyses and demonstrate that FLAMBE data align with downstream functional observations. Collectively, FLAMBE advances our understanding of BAX activation and fills a methodological void for studying BAX with broad applications in cell biology and therapeutic development. MOTIVATION In vitro BAX activation studies are invaluable platforms for studying cellular and pharmacological modulators of apoptosis. The gold standard for studying BAX function relies on membrane permeabilization assays, which assess the pore-forming activity of oligomeric BAX. However, there are currently no rapid or kinetic assays to interrogate real-time activation of monomeric BAX in solution, thereby limiting any molecular insights that occur upstream of mitochondrial permeabilization. Furthermore, available methods to observe the activation of monomeric BAX suffer from low throughput and static observations. To address this methodological gap, we developed FLAMBE, a kinetic fluorescence polarization-based assay to measure monomeric BAX activation in solution via concomitant displacement of a labeled peptide. This approach maintains the benefits of rapid kinetic data generation in a low-cost microplate format without requiring specialized equipment or large quantities of protein. FLAMBE compliments available experimental strategies and expands the accessibility of investigators to monitor early steps within the BAX activation continuum.
Collapse
Affiliation(s)
- Jesse D. Gelles
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jarvier N. Mohammed
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Yiyang Chen
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Tara M. Sebastian
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jerry Edward Chipuk
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| |
Collapse
|
8
|
Bcl-2 Family Members and the Mitochondrial Import Machineries: The Roads to Death. Biomolecules 2022; 12:biom12020162. [PMID: 35204663 PMCID: PMC8961529 DOI: 10.3390/biom12020162] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 01/27/2023] Open
Abstract
The localization of Bcl-2 family members at the mitochondrial outer membrane (MOM) is a crucial step in the implementation of apoptosis. We review evidence showing the role of the components of the mitochondrial import machineries (translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM)) in the mitochondrial localization of Bcl-2 family members and how these machineries regulate the function of pro- and anti-apoptotic proteins in resting cells and in cells committed into apoptosis.
Collapse
|
9
|
Luo SW, Xiong NX, Luo ZY, Luo KK, Liu SJ, Wu C, Wang S, Wen M. Effect of Lipopolysaccharide (LPS) stimulation on apoptotic process and oxidative stress in fibroblast cell of hybrid crucian carp compared with those of Carassius cuvieri and Carassius auratus red var. Comp Biochem Physiol C Toxicol Pharmacol 2021; 248:109085. [PMID: 34052412 DOI: 10.1016/j.cbpc.2021.109085] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 05/02/2021] [Accepted: 05/19/2021] [Indexed: 12/25/2022]
Abstract
Bacterial LPS is a heat-stable endotoxin and wall components of gram negative bacteria, which can exhibit a toxicological effect on physiology and biochemical activities of fish. In this study, we investigated the effect of LPS exposure on cell viability, oxidative stress, caspase activity and immune-related gene expressions in cultured fin cell lines of red crucian carp, white crucian carp and their hybrid offspring. LPS stimulation could reduce fish cell viability, whereas gene expression levels and promoter activities in inflammatory signals increased dramatically. Moreover, enhanced levels of intracellular oxidative stress and decreased levels of mitochondrial membrane potential (MMP) were observed in LPS-induced fish cells. N-Acetyl-L-cysteine (NAC) could alleviate LPS-stimulated reactive oxygen species (ROS) generation and caspase-3 activity in fish cells. These results suggested that ROS-mediated cytotoxic stress was involved in LPS-induced inflammation and mitochondrial damage in cultured fish cells.
Collapse
Affiliation(s)
- Sheng-Wei Luo
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China.
| | - Ning-Xia Xiong
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Zi-Ye Luo
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Kai-Kun Luo
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Shao-Jun Liu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China.
| | - Chang Wu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Shi Wang
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Ming Wen
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| |
Collapse
|
10
|
Bloch NB, Wales TE, Prew MS, Levy HR, Engen JR, Walensky LD. The conformational stability of pro-apoptotic BAX is dictated by discrete residues of the protein core. Nat Commun 2021; 12:4932. [PMID: 34389733 PMCID: PMC8363748 DOI: 10.1038/s41467-021-25200-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 07/28/2021] [Indexed: 11/09/2022] Open
Abstract
BAX is a pro-apoptotic member of the BCL-2 family, which regulates the balance between cellular life and death. During homeostasis, BAX predominantly resides in the cytosol as a latent monomer but, in response to stress, transforms into an oligomeric protein that permeabilizes the mitochondria, leading to apoptosis. Because renegade BAX activation poses a grave risk to the cell, the architecture of BAX must ensure monomeric stability yet enable conformational change upon stress signaling. The specific structural features that afford both stability and dynamic flexibility remain ill-defined and represent a critical control point of BAX regulation. We identify a nexus of interactions involving four residues of the BAX core α5 helix that are individually essential to maintaining the structure and latency of monomeric BAX and are collectively required for dimeric assembly. The dual yet distinct roles of these residues reveals the intricacy of BAX conformational regulation and opportunities for therapeutic modulation.
Collapse
Affiliation(s)
- Noah B Bloch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Thomas E Wales
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA
| | - Michelle S Prew
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Hannah R Levy
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA
| | - 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.
| |
Collapse
|
11
|
Lindenboim L, Grozki D, Amsalem-Zafran AR, Peña-Blanco A, Gundersen GG, Borner C, Hodzic D, Garcia-Sáez AJ, Worman HJ, Stein R. Apoptotic stress induces Bax-dependent, caspase-independent redistribution of LINC complex nesprins. Cell Death Discov 2020; 6:90. [PMID: 33024575 PMCID: PMC7501853 DOI: 10.1038/s41420-020-00327-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/28/2020] [Accepted: 09/01/2020] [Indexed: 12/24/2022] Open
Abstract
The canonical function of Bcl-2 family proteins is to regulate mitochondrial membrane integrity. In response to apoptotic signals the multi-domain pro-apoptotic proteins Bax and Bak are activated and perforate the mitochondrial outer membrane by a mechanism which is inhibited by their interaction with pro-survival members of the family. However, other studies have shown that Bax and Bak may have additional, non-canonical functions, which include stress-induced nuclear envelope rupture and discharge of nuclear proteins into the cytosol. We show here that the apoptotic stimuli cisplatin and staurosporine induce a Bax/Bak-dependent degradation and subcellular redistribution of nesprin-1 and nesprin-2 but not nesprin-3, of the linker of nucleoskeleton and cytoskeleton (LINC) complex. The degradation and redistribution were caspase-independent and did not occur in Bax/Bak double knockout (DKO) mouse embryo fibroblasts (MEFs). Re-expression of Bax in Bax/Bak DKO MEFs restored stress-induced redistribution of nesprin-2 by a mechanism which requires Bax membrane localization and integrity of the α helices 5/6, and the Bcl-2 homology 3 (BH3) domain. We found that nesprin-2 interacts with Bax in close proximity to perinuclear mitochondria in mouse and human cells. This interaction requires the mitochondrial targeting and N-terminal region but not the BH3 domain of Bax. Our results identify nesprin-2 as a Bax binding partner and also a new function of Bax in impairing the integrity of the LINC complex.
Collapse
Affiliation(s)
- Liora Lindenboim
- Department of Neurobiology, School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978 Israel
| | - Dan Grozki
- Department of Neurobiology, School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978 Israel
| | - Ayelet R. Amsalem-Zafran
- Department of Neurobiology, School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978 Israel
| | - Aida Peña-Blanco
- Interfaculty Institute of Biochemistry, University of Tübingen, 72074 Tübingen, Germany
| | - Gregg G. Gundersen
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032 USA
| | - Christoph Borner
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University of Freiburg, Stefan Meier Strasse 17, D-79104 Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University of Freiburg, Albertstrasse 19a, D-79104 Freiburg, Germany
| | - Didier Hodzic
- Department of Developmental Biology, Washington University School of Medicine, 660S. Euclid Avenue, St Louis, MO 63110 USA
| | - Ana J. Garcia-Sáez
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Howard J. Worman
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032 USA
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032 USA
| | - Reuven Stein
- Department of Neurobiology, School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978 Israel
| |
Collapse
|
12
|
Popgeorgiev N, Sa JD, Jabbour L, Banjara S, Nguyen TTM, Akhavan-E-Sabet A, Gadet R, Ralchev N, Manon S, Hinds MG, Osigus HJ, Schierwater B, Humbert PO, Rimokh R, Gillet G, Kvansakul M. Ancient and conserved functional interplay between Bcl-2 family proteins in the mitochondrial pathway of apoptosis. SCIENCE ADVANCES 2020; 6:6/40/eabc4149. [PMID: 32998881 PMCID: PMC7527217 DOI: 10.1126/sciadv.abc4149] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 08/10/2020] [Indexed: 06/10/2023]
Abstract
In metazoans, Bcl-2 family proteins are major regulators of mitochondrially mediated apoptosis; however, their evolution remains poorly understood. Here, we describe the molecular characterization of the four members of the Bcl-2 family in the most primitive metazoan, Trichoplax adhaerens All four trBcl-2 homologs are multimotif Bcl-2 group, with trBcl-2L1 and trBcl-2L2 being highly divergent antiapoptotic Bcl-2 members, whereas trBcl-2L3 and trBcl-2L4 are homologs of proapoptotic Bax and Bak, respectively. trBax expression permeabilizes the mitochondrial outer membrane, while trBak operates as a BH3-only sensitizer repressing antiapoptotic activities of trBcl-2L1 and trBcl-2L2. The crystal structure of a trBcl-2L2:trBak BH3 complex reveals that trBcl-2L2 uses the canonical Bcl-2 ligand binding groove to sequester trBak BH3, indicating that the structural basis for apoptosis control is conserved from T. adhaerens to mammals. Finally, we demonstrate that both trBax and trBak BH3 peptides bind selectively to human Bcl-2 homologs to sensitize cancer cells to chemotherapy treatment.
Collapse
Affiliation(s)
- Nikolay Popgeorgiev
- Université de Lyon, Centre de recherche en cancérologie de Lyon, U1052 INSERM, UMR CNRS 5286, Université Lyon I, Centre Léon Bérard, 28 rue Laennec, 69008 Lyon, France.
| | - Jaison D Sa
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Lea Jabbour
- Université de Lyon, Centre de recherche en cancérologie de Lyon, U1052 INSERM, UMR CNRS 5286, Université Lyon I, Centre Léon Bérard, 28 rue Laennec, 69008 Lyon, France
| | - Suresh Banjara
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Trang Thi Minh Nguyen
- Université de Lyon, Centre de recherche en cancérologie de Lyon, U1052 INSERM, UMR CNRS 5286, Université Lyon I, Centre Léon Bérard, 28 rue Laennec, 69008 Lyon, France
| | - Aida Akhavan-E-Sabet
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Rudy Gadet
- Université de Lyon, Centre de recherche en cancérologie de Lyon, U1052 INSERM, UMR CNRS 5286, Université Lyon I, Centre Léon Bérard, 28 rue Laennec, 69008 Lyon, France
| | - Nikola Ralchev
- Université de Lyon, Centre de recherche en cancérologie de Lyon, U1052 INSERM, UMR CNRS 5286, Université Lyon I, Centre Léon Bérard, 28 rue Laennec, 69008 Lyon, France
| | - Stéphen Manon
- Institut de Biochimie et de Génétique Cellulaires, UMR5095, CNRS et Université de Bordeaux, CS61390, 1 Rue Camille Saint-Saëns, 33000 Bordeaux, France
| | - Mark G Hinds
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne 3050, Australia
| | - Hans-Jürgen Osigus
- Institute of Animal Ecology, Division of Molecular Evolution, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Bernd Schierwater
- Institute of Animal Ecology, Division of Molecular Evolution, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY 10024, USA
| | - Patrick O Humbert
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Ruth Rimokh
- Université de Lyon, Centre de recherche en cancérologie de Lyon, U1052 INSERM, UMR CNRS 5286, Université Lyon I, Centre Léon Bérard, 28 rue Laennec, 69008 Lyon, France
| | - Germain Gillet
- Université de Lyon, Centre de recherche en cancérologie de Lyon, U1052 INSERM, UMR CNRS 5286, Université Lyon I, Centre Léon Bérard, 28 rue Laennec, 69008 Lyon, France.
| | - Marc Kvansakul
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia.
| |
Collapse
|
13
|
Classical swine fever virus N pro antagonises IRF3 to prevent IFN-independent TLR3 and RIG-I-mediated apoptosis. J Virol 2020; 95:JVI.01136-20. [PMID: 33328306 PMCID: PMC8092839 DOI: 10.1128/jvi.01136-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Classical swine fever virus (CSFV) is the causative agent of classical swine fever, a notifiable disease of economic importance that causes severe leukopenia, fever and haemorrhagic disease in domesticated pigs and wild boar across the globe. CSFV has been shown to antagonise the induction of type I IFN, partly through a function of its N-terminal protease (Npro) which binds IRF3 and targets it for proteasomal degradation. Additionally, Npro has been shown to antagonise apoptosis triggered by the dsRNA-homolog poly(I:C), however the exact mechanism by which this is achieved has not been fully elucidated. In this study we confirm the ability of Npro to inhibit dsRNA-mediated apoptosis and show that Npro is also able to antagonise Sendai virus-mediated apoptosis in PK-15 cells. Gene edited PK-15 cell lines were used to show the dsRNA-sensing pathogen recognition receptors (PRRs) TLR3 and RIG-I specifically respond to poly(I:C) and SeV respectively, subsequently triggering apoptosis through pathways that converge on IRF3 and culminate in the cleavage of caspase-3. Importantly, this IRF3-mediated apoptosis was found to be dependent on transcription-independent functions of IRF3 and also on Bax, a pro-apoptotic Bcl-2 family protein, through a direct interaction between the two proteins. Deletion of IRF3, stable expression of Npro and infection with wild-type CSFV were found to antagonise the mitochondrial localisation of Bax, a key hallmark of the intrinsic, mitochondrial pathway of apoptosis. Together, these findings show that Npro's putative interaction with IRF3 is involved not only in its antagonism of type I IFN, but also dsRNA-mediated mitochondrial apoptosis.Importance Responsible for severe haemorrhagic disease in domestic pigs and wild boar, classical swine fever is recognised by the World Organisation for Animal Health (OIE) and European Union as a notifiable disease of economic importance. Persistent infection, immunotolerance and early dissemination of the virus at local sites of infection have been linked to the antagonism of type I IFN induction by Npro This protein may further contribute to these phenomena by antagonising the induction of dsRNA-mediated apoptosis. Ultimately, apoptosis is an important innate mechanism by which cells counter viruses at local sites of infection, thus preventing wider spread and dissemination within the host, potentially also contributing to the onset of persistence. Elucidation of the mechanism by which Npro antagonises the apoptotic response will help inform the development of rationally-designed live-attenuated vaccines and antivirals for control of outbreaks in typically CSFV-free countries.
Collapse
|
14
|
Guo M, Lv M, Shao Y, Zhang W, Zhao X, Li C. Bax functions as coelomocyte apoptosis regulator in the sea cucumber Apostichopus japonicus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 102:103490. [PMID: 31494220 DOI: 10.1016/j.dci.2019.103490] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 08/26/2019] [Accepted: 08/30/2019] [Indexed: 06/10/2023]
Abstract
Bcl-2-associated X (Bax) belongs to the Bcl-2 protein family and its pro-apoptotic function has been confirmed in many vertebrate species. However, the functional role of Bax in apoptosis in invertebrates is limited. Here, a Bax homologue (AjBax) in Apostichopus japonicas was cloned and characterized, and its pro-apoptotic function explored. In healthy sea cucumbers, AjBax was expressed in coelomocyte with the highest levels. AjBax mRNA and protein levels were significantly induced in coelomocytes post Vibrio splendidus challenge in vivo and LPS-exposed in vitro. Moreover, siRNA-mediated AjBax knockdown in coelomocyte significantly decreased AjBax mRNA and protein levels as well as the apoptosis levels of coelomocyte. Furthermore, AjBax protein levels and coelomocyte apoptosis levels could be partially recovered to their original levels after supplementation with recombinant AjBax. Our results support that AjBax has a similar function to Bax proteins in vertebrates and that it may serve as a pro-apoptotic regulator in sea cucumbers.
Collapse
Affiliation(s)
- Ming Guo
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Miao Lv
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Yina Shao
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Weiwei Zhang
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Xuelin Zhao
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Chenghua Li
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China.
| |
Collapse
|
15
|
Maes ME, Grosser JA, Fehrman RL, Schlamp CL, Nickells RW. Completion of BAX recruitment correlates with mitochondrial fission during apoptosis. Sci Rep 2019; 9:16565. [PMID: 31719602 PMCID: PMC6851089 DOI: 10.1038/s41598-019-53049-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/23/2019] [Indexed: 12/30/2022] Open
Abstract
BAX, a member of the BCL2 gene family, controls the committed step of the intrinsic apoptotic program. Mitochondrial fragmentation is a commonly observed feature of apoptosis, which occurs through the process of mitochondrial fission. BAX has consistently been associated with mitochondrial fission, yet how BAX participates in the process of mitochondrial fragmentation during apoptosis remains to be tested. Time-lapse imaging of BAX recruitment and mitochondrial fragmentation demonstrates that rapid mitochondrial fragmentation during apoptosis occurs after the complete recruitment of BAX to the mitochondrial outer membrane (MOM). The requirement of a fully functioning BAX protein for the fission process was demonstrated further in BAX/BAK-deficient HCT116 cells expressing a P168A mutant of BAX. The mutant performed fusion to restore the mitochondrial network. but was not demonstrably recruited to the MOM after apoptosis induction. Under these conditions, mitochondrial fragmentation was blocked. Additionally, we show that loss of the fission protein, dynamin-like protein 1 (DRP1), does not temporally affect the initiation time or rate of BAX recruitment, but does reduce the final level of BAX recruited to the MOM during the late phase of BAX recruitment. These correlative observations suggest a model where late-stage BAX oligomers play a functional part of the mitochondrial fragmentation machinery in apoptotic cells.
Collapse
Affiliation(s)
- M E Maes
- Department of Ophthalmology and Visual Sciences, University of Wisconsin - Madison, Madison, WI, USA.,Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - J A Grosser
- Department of Ophthalmology and Visual Sciences, University of Wisconsin - Madison, Madison, WI, USA
| | - R L Fehrman
- Department of Ophthalmology and Visual Sciences, University of Wisconsin - Madison, Madison, WI, USA
| | - C L Schlamp
- Department of Ophthalmology and Visual Sciences, University of Wisconsin - Madison, Madison, WI, USA
| | - R W Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin - Madison, Madison, WI, USA.
| |
Collapse
|
16
|
Lu P, Vander Mause ER, Redd Bowman KE, Brown SM, Ahne L, Lim CS. Mitochondrially targeted p53 or DBD subdomain is superior to wild type p53 in ovarian cancer cells even with strong dominant negative mutant p53. J Ovarian Res 2019; 12:45. [PMID: 31092272 PMCID: PMC6521536 DOI: 10.1186/s13048-019-0516-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 04/18/2019] [Indexed: 12/26/2022] Open
Abstract
Background While tumor suppressor p53 functions primarily as a transcription factor in the nucleus, cellular stress can cause p53 to translocate to the mitochondria and directly trigger a rapid apoptotic response. We have previously shown that fusing p53 (or its DNA binding domain, DBD, alone) to the mitochondrial targeting signal (MTS) from Bak or Bax can target p53 to the mitochondria and induce apoptosis in gynecological cancer cell lines including cervical cancer cells (HeLa; wt p53), ovarian cancer cells (SKOV-3; p53 267del non-expressing), and breast cancer cells (T47D; L194F p53 mutation). However, p53 with Bak or Bax MTSs have not been previously tested in cancers with strong dominant negative (DN) mutant p53 which are capable of inactivating wt p53 by homo-oligomerization. Since p53-Bak or Bax MTS constructs act as monomers, they are not subject to DN inhibition. For this study, the utility of p53-Bak or p53-Bax MTS constructs was tested for ovarian cancers which are known to have varying p53 statuses, including a strong DN contact mutant p53 (Ovcar-3 cells), a p53 DN structural mutant (Kuramochi cells), and a p53 wild type, low expressing cells (ID8). Results Our mitochondrial p53 constructs were tested for their ability to localize to the mitochondria in both mutant non-expressing p53 (Skov-3) and p53 structural mutant (Kuramochi) cell lines using fluorescence microscopy and a nuclear transcriptional activity assay. The apoptotic activity of these mitochondrial constructs was determined using a mitochondrial outer membrane depolarization assay (TMRE), caspase assay, and a late stage cell death assay (7-AAD). We also tested the possibility of using our constructs with paclitaxel, the current standard of care in ovarian cancer treatment. Our data indicates that our mitochondrial p53 constructs are able to effectively localize to the mitochondria in cancer cells with structural mutant p53 and induce apoptosis in many ovarian cancer cell lines with different p53 statuses. These constructs can also be used in combination with paclitaxel for an increased apoptotic effect. Conclusions The results suggest that targeting p53 to mitochondria can be a new strategy for ovarian cancer treatment. Electronic supplementary material The online version of this article (10.1186/s13048-019-0516-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Phong Lu
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S 2000 E Rm 301, Salt Lake City, UT, 84112, USA
| | - Erica R Vander Mause
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S 2000 E Rm 301, Salt Lake City, UT, 84112, USA
| | - Katherine E Redd Bowman
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S 2000 E Rm 301, Salt Lake City, UT, 84112, USA
| | - Sarah M Brown
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S 2000 E Rm 301, Salt Lake City, UT, 84112, USA
| | - Lisa Ahne
- Philipps-Universitat Marburg, Biegenstraße 10, Marburg, 35037, Germany
| | - Carol S Lim
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S 2000 E Rm 301, Salt Lake City, UT, 84112, USA.
| |
Collapse
|
17
|
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
|
18
|
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.
Collapse
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.
| |
Collapse
|
19
|
Topology of active, membrane-embedded Bax in the context of a toroidal pore. Cell Death Differ 2018; 25:1717-1731. [PMID: 30185826 DOI: 10.1038/s41418-018-0184-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/20/2018] [Accepted: 05/21/2018] [Indexed: 01/18/2023] Open
Abstract
Bax is a Bcl-2 protein critical for apoptosis induction. In healthy cells, Bax is mostly a monomeric, cytosolic protein, while upon apoptosis initiation it inserts into the outer mitochondrial membrane, oligomerizes, and forms pores that release proapoptotic factors like Cytochrome c into the cytosol. The structures of active Bax and its homolog Bak are only partially understood and the topology of the proteins with respect to the membrane bilayer is controversially described in the literature. Here, we systematically review and examine the protein-membrane, protein-water, and protein-protein contacts of the nine helices of active Bax and Bak, and add a new set of topology data obtained by fluorescence and EPR methods. We conclude based on the consistent part of the datasets that the core/dimerization domain of Bax (Bak) is water exposed with only helices 4 and 5 in membrane contact, whereas the piercing/latch domain is in peripheral membrane contact, with helix 9 being transmembrane. Among the available structural models, those considering the dimerization/core domain at the rim of a toroidal pore are the most plausible to describe the active state of the proteins, although the structural flexibility of the piercing/latch domain does not allow unambiguous discrimination between the existing models.
Collapse
|
20
|
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.
Collapse
|
21
|
Hou D, Che Z, Chen P, Zhang W, Chu Y, Yang D, Liu J. Suppression of AURKA alleviates p27 inhibition on Bax cleavage and induces more intensive apoptosis in gastric cancer. Cell Death Dis 2018; 9:781. [PMID: 30013101 PMCID: PMC6048174 DOI: 10.1038/s41419-018-0823-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/03/2018] [Accepted: 05/31/2018] [Indexed: 12/13/2022]
Abstract
Bax is a key molecule in mitochondria-apoptosis pathway, however it is not always an efficient apoptosis inducer in chemotherapeutic agents-treated cancer cells. Here, we found that specific inhibition of AURKA by MLN8237-induced calpain-mediated Bax cleavage at N-terminal 33th asparagine (c-Bax) to promote apoptosis. The c-Bax, as Bax, could also efficiently located to mitochondria but c-Bax is a stronger apoptosis inducer than Bax. Morever, c-Bax-induced apoptosis could not be blocked by the canonical Bax inhibitor, Bcl-2. Further study found p27 was degraded and subsequently Bax was transformed to c-Bax through calpain. Also, p27 efficiently inhibited Bax cleavage and p27 knockdown sensitized apoptosis through Bax cleavage when cancer cells were treated with MLN8237. It is also demonstrated that the anti-apoptotic role of p27 lies its cytoplasmic localization. Finally, we found that the positive correlation between AURKA and p27 in advanced gastric cancer patients. In conclusion, we found that MNL8237 suppressed cell growth by regulating calpain-dependent Bax cleavage and p27 dysregulation in gastric cancer cells.
Collapse
Affiliation(s)
- Daisen Hou
- Department of Digestive Diseases of Huashan Hospital and Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Zhihui Che
- Department of Digestive Diseases, National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Ping Chen
- Department of Digestive Diseases of Huashan Hospital and Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Wenli Zhang
- Department of Digestive Diseases, National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Yiwei Chu
- Institute of Biomedical Sciences and Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Dongqin Yang
- Department of Digestive Diseases, National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China.
| | - Jie Liu
- Department of Digestive Diseases of Huashan Hospital and Institute of Biomedical Sciences, Fudan University, Shanghai, China. .,Department of Digestive Diseases, National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China.
| |
Collapse
|
22
|
Xiao K, Zhao W, Zhou L, Chang DC. Alpha 5/6 helix domains together with N-terminus determine the apoptotic potency of the Bcl-2 family proteins. Apoptosis 2018; 21:1214-1226. [PMID: 27553060 DOI: 10.1007/s10495-016-1283-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A critical process in apoptosis is the permeabilization of the mitochondrial outer membrane (MOM). This process is known to be regulated by the multi-domain Bcl-2 family proteins. For example, the pro-apoptotic proteins Bax and Bak are responsible for forming pores at MOM. The anti-apoptotic proteins (including Bcl-2, Mcl-1 and Bcl-xL), on the other hand, can inhibit this pore-forming process. Interestingly, although these two subgroups of proteins perform opposite apoptotic functions, their structures are very similar. This raises two highly interesting questions: (1) Why do these structurally similar proteins play opposite roles in apoptosis? (2) What are the roles of different functional domains of a Bcl-2 family protein in determining its apoptotic property? In this study, we generated a series of deletion mutants and substitution chimera, and used a combination of molecular biology, bio-informatics and living cell imaging techniques to answer these questions. Our major findings are: (1) All of the Bcl-2 family proteins appear to possess an intrinsic pro-apoptotic property. (2) The N-termini of these proteins play an active role in suppressing their pro-apoptotic function. (3) The apoptotic potency is positively correlated with membrane affinity of the alpha 5/6 helix domains. (4) Charge distribution flanking the alpha 5/6 helices is also important for the apoptotic potency. These findings explain why different members of Bcl-2 family proteins with similar domain composition can function oppositely in the apoptotic process.
Collapse
Affiliation(s)
- Kang Xiao
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Guangdong Engineering Research; Center for Marine Algal Biotechnology, College of Life Science and Oceanography; Key Laboratory of Optoeletronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoeletronic Engineering, Shenzhen University, 518060, Shenzhen, China
| | - Wenrui Zhao
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Liying Zhou
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Donald Choy Chang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
| |
Collapse
|
23
|
N-terminal acetylation modulates Bax targeting to mitochondria. Int J Biochem Cell Biol 2017; 95:35-42. [PMID: 29233735 DOI: 10.1016/j.biocel.2017.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/28/2017] [Accepted: 12/06/2017] [Indexed: 01/13/2023]
Abstract
The pro-apoptotic Bax protein is the main effector of mitochondrial permeabilization during apoptosis. Bax is controlled at several levels, including post-translational modifications such as phosphorylation and S-palmitoylation. However, little is known about the contribution of other protein modifications to Bax activity. Here, we used heterologous expression of human Bax in yeast to study the involvement of N-terminal acetylation by yNaa20p (yNatB) on Bax function. We found that human Bax is N-terminal (Nt-)acetylated by yNaa20p and that Nt-acetylation of Bax is essential to maintain Bax in an inactive conformation in the cytosol of yeast and Mouse Embryonic Fibroblast (MEF) cells. Bax accumulates in the mitochondria of yeast naa20Δ and Naa25-/- MEF cells, but does not promote cytochrome c release, suggesting that an additional step is required for full activation of Bax. Altogether, our results show that Bax N-terminal acetylation by NatB is involved in its mitochondrial targeting.
Collapse
|
24
|
Mañas A, Wang S, Nelson A, Li J, Zhao Y, Zhang H, Davis A, Xie B, Maltsev N, Xiang J. The functional domains for Bax∆2 aggregate-mediated caspase 8-dependent cell death. Exp Cell Res 2017; 359:342-355. [PMID: 28807790 PMCID: PMC5718386 DOI: 10.1016/j.yexcr.2017.08.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/07/2017] [Accepted: 08/08/2017] [Indexed: 01/09/2023]
Abstract
Bax∆2 is a functional pro-apoptotic Bax isoform having alterations in its N-terminus, but sharing the rest of its sequence with Baxα. Bax∆2 is unable to target mitochondria due to the loss of helix α1. Instead, it forms cytosolic aggregates and activates caspase 8. However, the functional domain(s) responsible for BaxΔ2 behavior have remained elusive. Here we show that disruption of helix α1 makes Baxα mimic the behavior of Bax∆2. However, the other alterations in the Bax∆2 N-terminus have no significant impact on aggregation or cell death. We found that the hallmark BH3 domain is necessary but not sufficient for aggregation-mediated cell death. We also noted that the core region shared by Baxα and Bax∆2 is required for the formation of large aggregates, which is essential for BaxΔ2 cytotoxicity. However, aggregation by itself is unable to trigger cell death without the C-terminus. Interestingly, the C-terminal helical conformation, not its primary sequence, appears to be critical for caspase 8 recruitment and activation. As Bax∆2 shares core and C-terminal sequences with most Bax isoforms, our results not only reveal a structural basis for Bax∆2-induced cell death, but also imply an intrinsic potential for aggregate-mediated caspase 8-dependent cell death in other Bax family members.
Collapse
Affiliation(s)
- Adriana Mañas
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Sheng Wang
- Human Genetics Department, Computation Institute, University of Chicago, Chicago, IL 60637, USA
| | - Adam Nelson
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jiajun Li
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Yu Zhao
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Huaiyuan Zhang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Aislinn Davis
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Bingqing Xie
- Department of Computer Science, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Natalia Maltsev
- Human Genetics Department, Computation Institute, University of Chicago, Chicago, IL 60637, USA
| | - Jialing Xiang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA.
| |
Collapse
|
25
|
Live-cell imaging to measure BAX recruitment kinetics to mitochondria during apoptosis. PLoS One 2017; 12:e0184434. [PMID: 28880942 PMCID: PMC5589231 DOI: 10.1371/journal.pone.0184434] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/23/2017] [Indexed: 12/03/2022] Open
Abstract
The pro-apoptotic BCL2 gene family member, BAX, plays a pivotal role in the intrinsic apoptotic pathway. Under cellular stress, BAX recruitment to the mitochondria occurs when activated BAX forms dimers, then oligomers, to initiate mitochondria outer membrane permeabilization (MOMP), a process critical for apoptotic progression. The activation and recruitment of BAX to form oligomers has been studied for two decades using fusion proteins with a fluorescent reporter attached in-frame to the BAX N-terminus. We applied high-speed live cell imaging to monitor the recruitment of BAX fusion proteins in dying cells. Data from time-lapse imaging was validated against the activity of endogenous BAX in cells, and analyzed using sigmoid mathematical functions to obtain detail of the kinetic parameters of the recruitment process at individual mitochondrial foci. BAX fusion proteins behave like endogenous BAX during apoptosis. Kinetic studies show that fusion protein recruitment is also minimally affected in cells lacking endogenous BAK or BAX genes, but that the kinetics are moderately, but significantly, different with different fluorescent tags in the fusion constructs. In experiments testing BAX recruitment in 3 different cell lines, our results show that regardless of cell type, once activated, BAX recruitment initiates simultaneously within a cell, but exhibits varying rates of recruitment at individual mitochondrial foci. Very early during BAX recruitment, pro-apoptotic molecules are released in the process of MOMP, but different molecules are released at different times and rates relative to the time of BAX recruitment initiation. These results provide a method for BAX kinetic analysis in living cells and yield greater detail of multiple characteristics of BAX-induced MOMP in living cells that were initially observed in cell free studies.
Collapse
|
26
|
Identification and expression analysis of alternatively spliced new transcript isoform of Bax gene in mouse. Gene 2017; 621:21-31. [DOI: 10.1016/j.gene.2017.04.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 04/07/2017] [Accepted: 04/12/2017] [Indexed: 12/29/2022]
|
27
|
Simonyan L, Légiot A, Lascu I, Durand G, Giraud MF, Gonzalez C, Manon S. The substitution of Proline 168 favors Bax oligomerization and stimulates its interaction with LUVs and mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1144-1155. [DOI: 10.1016/j.bbamem.2017.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 02/28/2017] [Accepted: 03/14/2017] [Indexed: 12/23/2022]
|
28
|
Basic Fibroblast Growth Factor Inhibits Apoptosis and Promotes Proliferation of Adipose-Derived Mesenchymal Stromal Cells Isolated from Patients with Type 2 Diabetes by Reducing Cellular Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:3027109. [PMID: 28168007 PMCID: PMC5267085 DOI: 10.1155/2017/3027109] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/15/2016] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes (T2D) is a chronic metabolic disorder affecting increasing number of people in developed countries. Therefore new strategies for treatment of T2D and its complications are of special interest. Nowadays, cellular therapies involving mesenchymal stromal cells that reside in adipose tissue (ASCs) constitute a promising approach; however, there are still many obstacles concerning safety and effectiveness that need to be overcome before ASCs could be engaged for the treatment of diabetes mellitus. One of the challenges is preventing ASCs from deterioration caused by elevated oxidative stress present in diabetes milieu. In the current study we investigated the effect of basic fibroblast growth factor (bFGF) treatment on ASCs isolated from patients with diagnosed T2D. We demonstrate here that cell exposition to bFGF in 5 and 10 ng/mL dosages results in improved morphology, increased proliferative activity, reduced cellular senescence and apoptosis, and decreased oxidative stress, indicating recovery of ASCs' function impaired by T2D. Therefore our results provide a support for bFGF as a potential therapeutic agent for improving stem cell-based approaches for the treatment of diabetes mellitus and its complications.
Collapse
|
29
|
Maes ME, Schlamp CL, Nickells RW. BAX to basics: How the BCL2 gene family controls the death of retinal ganglion cells. Prog Retin Eye Res 2017; 57:1-25. [PMID: 28064040 DOI: 10.1016/j.preteyeres.2017.01.002] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/22/2016] [Accepted: 01/03/2017] [Indexed: 12/19/2022]
Abstract
Retinal ganglion cell (RGC) death is the principal consequence of injury to the optic nerve. For several decades, we have understood that the RGC death process was executed by apoptosis, suggesting that there may be ways to therapeutically intervene in this cell death program and provide a more direct treatment to the cells and tissues affected in diseases like glaucoma. A major part of this endeavor has been to elucidate the molecular biological pathways active in RGCs from the point of axonal injury to the point of irreversible cell death. A major component of this process is the complex interaction of members of the BCL2 gene family. Three distinct family members of proteins orchestrate the most critical junction in the apoptotic program of RGCs, culminating in the activation of pro-apoptotic BAX. Once active, BAX causes irreparable damage to mitochondria, while precipitating downstream events that finish off a dying ganglion cell. This review is divided into two major parts. First, we summarize the extent of knowledge of how BCL2 gene family proteins interact to facilitate the activation and function of BAX. This area of investigation has rapidly changed over the last few years and has yielded a dramatically different mechanistic understanding of how the intrinsic apoptotic program is run in mammalian cells. Second, we provided a comprehensive analysis of nearly two decades of investigation of the role of BAX in the process of RGC death, much of which has provided many important insights into the overall pathophysiology of diseases like glaucoma.
Collapse
Affiliation(s)
- Margaret E Maes
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Cassandra L Schlamp
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Robert W Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA.
| |
Collapse
|
30
|
Evidence for Amino Acid Snorkeling from a High-Resolution, In Vivo Analysis of Fis1 Tail-Anchor Insertion at the Mitochondrial Outer Membrane. Genetics 2016; 205:691-705. [PMID: 28007883 PMCID: PMC5289845 DOI: 10.1534/genetics.116.196428] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 12/12/2016] [Indexed: 01/03/2023] Open
Abstract
Proteins localized to mitochondria by a carboxyl-terminal tail anchor (TA) play roles in apoptosis, mitochondrial dynamics, and mitochondrial protein import. To reveal characteristics of TAs that may be important for mitochondrial targeting, we focused our attention upon the TA of the Saccharomyces cerevisiaeFis1 protein. Specifically, we generated a library of Fis1p TA variants fused to the Gal4 transcription factor, then, using next-generation sequencing, revealed which Fis1p TA mutations inhibited membrane insertion and allowed Gal4p activity in the nucleus. Prompted by our global analysis, we subsequently analyzed the ability of individual Fis1p TA mutants to localize to mitochondria. Our findings suggest that the membrane-associated domain of the Fis1p TA may be bipartite in nature, and we encountered evidence that the positively charged patch at the carboxyl terminus of Fis1p is required for both membrane insertion and organelle specificity. Furthermore, lengthening or shortening of the Fis1p TA by up to three amino acids did not inhibit mitochondrial targeting, arguing against a model in which TA length directs insertion of TAs to distinct organelles. Most importantly, positively charged residues were more acceptable at several positions within the membrane-associated domain of the Fis1p TA than negatively charged residues. These findings, emerging from the first high-resolution analysis of an organelle targeting sequence by deep mutational scanning, provide strong, in vivo evidence that lysine and arginine can “snorkel,” or become stably incorporated within a lipid bilayer by placing terminal charges of their side chains at the membrane interface.
Collapse
|
31
|
Garner TP, Reyna DE, Priyadarshi A, Chen HC, Li S, Wu Y, Ganesan YT, Malashkevich VN, Cheng EH, Gavathiotis E. An Autoinhibited Dimeric Form of BAX Regulates the BAX Activation Pathway. Mol Cell 2016; 63:485-97. [PMID: 27425408 PMCID: PMC4975667 DOI: 10.1016/j.molcel.2016.06.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 04/22/2016] [Accepted: 05/06/2016] [Indexed: 12/21/2022]
Abstract
Pro-apoptotic BAX is a cell fate regulator playing an important role in cellular homeostasis and pathological cell death. BAX is predominantly localized in the cytosol, where it has a quiescent monomer conformation. Following a pro-apoptotic trigger, cytosolic BAX is activated and translocates to the mitochondria to initiate mitochondrial dysfunction and apoptosis. Here, cellular, biochemical, and structural data unexpectedly demonstrate that cytosolic BAX also has an inactive dimer conformation that regulates its activation. The full-length crystal structure of the inactive BAX dimer revealed an asymmetric interaction consistent with inhibition of the N-terminal conformational change of one protomer and the displacement of the C-terminal helix α9 of the second protomer. This autoinhibited BAX dimer dissociates to BAX monomers before BAX can be activated. Our data support a model whereby the degree of apoptosis induction is regulated by the conformation of cytosolic BAX and identify an unprecedented mechanism of cytosolic BAX inhibition.
Collapse
Affiliation(s)
- Thomas P Garner
- Department of Biochemistry and Department of Medicine, Albert Einstein Cancer Center, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Denis E Reyna
- Department of Biochemistry and Department of Medicine, Albert Einstein Cancer Center, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Amit Priyadarshi
- Department of Biochemistry and Department of Medicine, Albert Einstein Cancer Center, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Hui-Chen Chen
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sheng Li
- Department of Medicine and UCSD DXMS Proteomics Resource, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yang Wu
- Department of Biochemistry and Department of Medicine, Albert Einstein Cancer Center, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Yogesh Tengarai Ganesan
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Vladimir N Malashkevich
- Department of Biochemistry and Department of Biophysics and Physiology, Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Emily H Cheng
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Evripidis Gavathiotis
- Department of Biochemistry and Department of Medicine, Albert Einstein Cancer Center, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| |
Collapse
|
32
|
Luo SW, Wang WN, Sun ZM, Xie FX, Kong JR, Liu Y, Cheng CH. Molecular cloning, characterization and expression analysis of (B-cell lymphoma-2 associated X protein) Bax in the orange-spotted grouper (Epinephelus coioides) after the Vibrio alginolyticus challenge. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 60:66-79. [PMID: 26905633 DOI: 10.1016/j.dci.2016.02.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/13/2016] [Accepted: 02/15/2016] [Indexed: 06/05/2023]
Abstract
Bax is a pro-apoptotic member of Bcl-2 like superfamily, playing an important role in regulating the apoptosis. In this study, the full-length Bax (EcBax) was obtained, containing a 5'UTR of 64 bp, an ORF of 579 bp and a 3'UTR of 1021 bp. The EcBax gene encoded a polypeptide of 192 amino acids with an estimated molecular mass of 21.55 KDa and a predicted isoelectric point (pI) of 6.75. The deduced amino acid sequence analysis showed that EcBax comprised the conserved residues and the characteristic domains known to the critical function of Bax. qRT-PCR analysis revealed that EcBax mRNA was broadly expressed in all of the examined tissues, while the highest expression level was observed in blood, followed by the expression in liver, gill, spleen, kidney, heart, muscle and intestine. A sharp increase of EcBax expression was observed in the vibrio challenge group by comparing with those in the control. Subcellular localization analysis revealed that EcBax was predominantly localized in the cytoplasm. EcBax exerted a regulatory role in modulating the mitochondrial membrane potential, promoting the cytochrome c release, and then activating the downstream caspase signaling. Moreover, the overexpression of EcBax can decrease the cell viability and antagonize NF-kB, AP-1, Stat3 promoter activity in Hela cells. These results indicate that EcBax containing the conserved domain of pro-apoptotic member of Bcl-2 family may disrupt the mammalian signaling and play a regulative role in the apoptotic process.
Collapse
Affiliation(s)
- Sheng-Wei Luo
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Wei-Na Wang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China.
| | - Zuo-Ming Sun
- Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
| | - Fu-Xing Xie
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Jing-Rong Kong
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Yuan Liu
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Chang-Hong Cheng
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| |
Collapse
|
33
|
Große L, Wurm CA, Brüser C, Neumann D, Jans DC, Jakobs S. Bax assembles into large ring-like structures remodeling the mitochondrial outer membrane in apoptosis. EMBO J 2016; 35:402-13. [PMID: 26783364 PMCID: PMC4755111 DOI: 10.15252/embj.201592789] [Citation(s) in RCA: 220] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/23/2015] [Accepted: 12/01/2015] [Indexed: 12/05/2022] Open
Abstract
The Bcl-2 family proteins Bax and Bak are essential for the execution of many apoptotic programs. During apoptosis, Bax translocates to the mitochondria and mediates the permeabilization of the outer membrane, thereby facilitating the release of pro-apoptotic proteins. Yet the mechanistic details of the Bax-induced membrane permeabilization have so far remained elusive. Here, we demonstrate that activated Bax molecules, besides forming large and compact clusters, also assemble, potentially with other proteins including Bak, into ring-like structures in the mitochondrial outer membrane. STED nanoscopy indicates that the area enclosed by a Bax ring is devoid of mitochondrial outer membrane proteins such as Tom20, Tom22, and Sam50. This strongly supports the view that the Bax rings surround an opening required for mitochondrial outer membrane permeabilization (MOMP). Even though these Bax assemblies may be necessary for MOMP, we demonstrate that at least in Drp1 knockdown cells, these assemblies are not sufficient for full cytochrome c release. Together, our super-resolution data provide direct evidence in support of large Bax-delineated pores in the mitochondrial outer membrane as being crucial for Bax-mediated MOMP in cells.
Collapse
Affiliation(s)
- Lena Große
- Department of Neurology, University Medical Center of Göttingen, Göttingen, Germany Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christian A Wurm
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christian Brüser
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Daniel Neumann
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Daniel C Jans
- Department of Neurology, University Medical Center of Göttingen, Göttingen, Germany Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Stefan Jakobs
- Department of Neurology, University Medical Center of Göttingen, Göttingen, Germany Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| |
Collapse
|
34
|
Affiliation(s)
- Zhenyan Jiang
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, 91058Germany
| | - Hansi Zhang
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, 91058Germany
| | - Rainer A. Böckmann
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, 91058Germany
| |
Collapse
|
35
|
Mutation-induced protein interaction kinetics changes affect apoptotic network dynamic properties and facilitate oncogenesis. Proc Natl Acad Sci U S A 2015; 112:E4046-54. [PMID: 26170328 DOI: 10.1073/pnas.1502126112] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has been a consensus in cancer research that cancer is a disease caused primarily by genomic alterations, especially somatic mutations. However, the mechanism of mutation-induced oncogenesis is not fully understood. Here, we used the mitochondrial apoptotic pathway as a case study and performed a systematic analysis of integrating pathway dynamics with protein interaction kinetics to quantitatively investigate the causal molecular mechanism of mutation-induced oncogenesis. A mathematical model of the regulatory network was constructed to establish the functional role of dynamic bifurcation in the apoptotic process. The oncogenic mutation enrichment of each of the protein functional domains involved was found strongly correlated with the parameter sensitivity of the bifurcation point. We further dissected the causal mechanism underlying this correlation by evaluating the mutational influence on protein interaction kinetics using molecular dynamics simulation. We analyzed 29 matched mutant-wild-type and 16 matched SNP--wild-type protein systems. We found that the binding kinetics changes reflected by the changes of free energy changes induced by protein interaction mutations, which induce variations in the sensitive parameters of the bifurcation point, were a major cause of apoptosis pathway dysfunction, and mutations involved in sensitive interaction domains show high oncogenic potential. Our analysis provided a molecular basis for connecting protein mutations, protein interaction kinetics, network dynamics properties, and physiological function of a regulatory network. These insights provide a framework for coupling mutation genotype to tumorigenesis phenotype and help elucidate the logic of cancer initiation.
Collapse
|
36
|
Gai XY, Tang F, Ma J, Zeng KW, Wang SL, Wang YP, Wuren TN, Lu DX, Zhou Y, Ge RL. Antiproliferative effect of echinacoside on rat pulmonary artery smooth muscle cells under hypoxia. J Pharmacol Sci 2015; 126:155-63. [PMID: 25341567 DOI: 10.1254/jphs.14072fp] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
The main purpose of this study is to evaluate the effect of echinacoside (ECH) on hypoxia-induced proliferation of rat pulmonary artery smooth muscle cells (PASMCs) and the underlying mechanism. PASMCs were incubated under normoxia (nor), hypoxia (hyp), hypoxia + 0.35 mM ECH (hyp + ECH0.35), or hypoxia + 0.4 mM ECH (hyp + ECH0.4) for 24 h. Cell viability was assessed by MTS assays. The morphology of apoptosis was observed by DAPI staining, and apoptosis was quantified by flow cytometric analysis. Caspase-3 activity was determined by immunohistochemistry and real-time PCR, and the expressions of HIF-1α, Bax, Bcl-2, and Fas were determined by real-time PCR. Hypoxia induced significant proliferation of PASMCs, which could be inhibited by ECH in a concentration-dependent manner. This was associated with apoptosis of PASMCs. Z-DEVD-FMK could partly reduce the suppression effect of ECH; protein and gene expression of caspase-3 were significantly higher in the hyp + ECH0.4 and hyp + ECH0.35 groups. ECH significantly increased the expressions of Bax and Fas, but decreased the expressions of Bcl-2 and HIF-1α. ECH could inhibit hypoxia-induced proliferation of rat PASMCs, which is associated with apoptosis of PASMCs and improvement of hypoxia. ECH might be a potential agent for prevention and treatment of hypoxia-induced PAH.
Collapse
Affiliation(s)
- Xiang-Yun Gai
- Department of Pharmacology, School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Iyer S, Bell F, Westphal D, Anwari K, Gulbis J, Smith BJ, Dewson G, Kluck RM. Bak apoptotic pores involve a flexible C-terminal region and juxtaposition of the C-terminal transmembrane domains. Cell Death Differ 2015; 22:1665-75. [PMID: 25744027 DOI: 10.1038/cdd.2015.15] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 01/07/2015] [Accepted: 01/21/2015] [Indexed: 12/22/2022] Open
Abstract
Bak and Bax mediate apoptotic cell death by oligomerizing and forming a pore in the mitochondrial outer membrane. Both proteins anchor to the outer membrane via a C-terminal transmembrane domain, although its topology within the apoptotic pore is not known. Cysteine-scanning mutagenesis and hydrophilic labeling confirmed that in healthy mitochondria the Bak α9 segment traverses the outer membrane, with 11 central residues shielded from labeling. After pore formation those residues remained shielded, indicating that α9 does not line a pore. Bak (and Bax) activation allowed linkage of α9 to neighboring α9 segments, identifying an α9:α9 interface in Bak (and Bax) oligomers. Although the linkage pattern along α9 indicated a preferred packing surface, there was no evidence of a dimerization motif. Rather, the interface was invoked in part by Bak conformation change and in part by BH3:groove dimerization. The α9:α9 interaction may constitute a secondary interface in Bak oligomers, as it could link BH3:groove dimers to high-order oligomers. Moreover, as high-order oligomers were generated when α9:α9 linkage in the membrane was combined with α6:α6 linkage on the membrane surface, the α6-α9 region in oligomerized Bak is flexible. These findings provide the first view of Bak carboxy terminus (C terminus) membrane topology within the apoptotic pore.
Collapse
Affiliation(s)
- S Iyer
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - F Bell
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia
| | - D Westphal
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - K Anwari
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - J Gulbis
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - B J Smith
- Department of Chemistry and Physics, La Trobe Institute for Molecular Sciences, La Trobe University, Melbourne, Victoria 3086, Australia
| | - G Dewson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - R M Kluck
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| |
Collapse
|
38
|
How do viruses control mitochondria-mediated apoptosis? Virus Res 2015; 209:45-55. [PMID: 25736565 PMCID: PMC7114537 DOI: 10.1016/j.virusres.2015.02.026] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 12/16/2022]
Abstract
There is no doubt that viruses require cells to successfully reproduce and effectively infect the next host. The question is what is the fate of the infected cells? All eukaryotic cells can "sense" viral infections and exhibit defence strategies to oppose viral replication and spread. This often leads to the elimination of the infected cells by programmed cell death or apoptosis. This "sacrifice" of infected cells represents the most primordial response of multicellular organisms to viruses. Subverting host cell apoptosis, at least for some time, is therefore a crucial strategy of viruses to ensure their replication, the production of essential viral proteins, virus assembly and the spreading to new hosts. For that reason many viruses harbor apoptosis inhibitory genes, which once inside infected cells are expressed to circumvent apoptosis induction during the virus reproduction phase. On the other hand, viruses can take advantage of stimulating apoptosis to (i) facilitate shedding and hence dissemination, (ii) to prevent infected cells from presenting viral antigens to the immune system or (iii) to kill non-infected bystander and immune cells which would limit viral propagation. Hence the decision whether an infected host cell undergoes apoptosis or not depends on virus type and pathogenicity, its capacity to oppose antiviral responses of the infected cells and/or to evade any attack from immune cells. Viral genomes have therefore been adapted throughout evolution to satisfy the need of a particular virus to induce or inhibit apoptosis during its life cycle. Here we review the different strategies used by viruses to interfere with the two major apoptosis as well as with the innate immune signaling pathways in mammalian cells. We will focus on the intrinsic mitochondrial pathway and discuss new ideas about how particular viruses could activately engage mitochondria to induce apoptosis of their host.
Collapse
|
39
|
Todt F, Cakir Z, Reichenbach F, Emschermann F, Lauterwasser J, Kaiser A, Ichim G, Tait SWG, Frank S, Langer HF, Edlich F. Differential retrotranslocation of mitochondrial Bax and Bak. EMBO J 2014; 34:67-80. [PMID: 25378477 DOI: 10.15252/embj.201488806] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The Bcl-2 proteins Bax and Bak can permeabilize the outer mitochondrial membrane and commit cells to apoptosis. Pro-survival Bcl-2 proteins control Bax by constant retrotranslocation into the cytosol of healthy cells. The stabilization of cytosolic Bax raises the question whether the functionally redundant but largely mitochondrial Bak shares this level of regulation. Here we report that Bak is retrotranslocated from the mitochondria by pro-survival Bcl-2 proteins. Bak is present in the cytosol of human cells and tissues, but low shuttling rates cause predominant mitochondrial Bak localization. Interchanging the membrane anchors of Bax and Bak reverses their subcellular localization compared to the wild-type proteins. Strikingly, the reduction of Bax shuttling to the level of Bak retrotranslocation results in full Bax toxicity even in absence of apoptosis induction. Thus, fast Bax retrotranslocation is required to protect cells from commitment to programmed death.
Collapse
Affiliation(s)
- Franziska Todt
- Institute for Biochemistry and Molecular Biology University of Freiburg, Freiburg, Germany Spemann Graduate School of Biology and Medicine SGBM, Freiburg, Germany Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Zeynep Cakir
- Institute for Biochemistry and Molecular Biology University of Freiburg, Freiburg, Germany Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Frank Reichenbach
- Institute for Biochemistry and Molecular Biology University of Freiburg, Freiburg, Germany Spemann Graduate School of Biology and Medicine SGBM, Freiburg, Germany Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Frederic Emschermann
- Section for Cardioimmunology, University of Tübingen, Tübingen, Germany Department of Cardiovascular Medicine, University Hospital University of Tübingen, Tübingen, Germany
| | - Joachim Lauterwasser
- Institute for Biochemistry and Molecular Biology University of Freiburg, Freiburg, Germany Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Andrea Kaiser
- Institute for Biochemistry and Molecular Biology University of Freiburg, Freiburg, Germany
| | - Gabriel Ichim
- Cancer Research UK Beatson Institute University of Glasgow, Glasgow, UK
| | - Stephen W G Tait
- Cancer Research UK Beatson Institute University of Glasgow, Glasgow, UK
| | - Stephan Frank
- Division of Neuropathology, Institute of Pathology Basel University Hospitals, Basel, Switzerland
| | - Harald F Langer
- Section for Cardioimmunology, University of Tübingen, Tübingen, Germany Department of Cardiovascular Medicine, University Hospital University of Tübingen, Tübingen, Germany
| | - Frank Edlich
- Institute for Biochemistry and Molecular Biology University of Freiburg, Freiburg, Germany Spemann Graduate School of Biology and Medicine SGBM, Freiburg, Germany BIOSS, Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| |
Collapse
|
40
|
Chi X, Kale J, Leber B, Andrews DW. Regulating cell death at, on, and in membranes. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:2100-13. [PMID: 24927885 DOI: 10.1016/j.bbamcr.2014.06.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 05/29/2014] [Accepted: 06/03/2014] [Indexed: 11/17/2022]
Abstract
Bcl-2 family proteins are central regulators of apoptosis. Various family members are located in the cytoplasm, endoplasmic reticulum, and mitochondrial outer membrane in healthy cells. However during apoptosis most of the interactions between family members that determine the fate of the cell occur at the membranes of intracellular organelles. It has become evident that interactions with membranes play an active role in the regulation of Bcl-2 family protein interactions. Here we provide an overview of various models proposed to explain how the Bcl-2 family regulates apoptosis and discuss how membrane binding affects the structure and function of each of the three categories of Bcl-2 proteins (pro-apoptotic, pore-forming, and anti-apoptotic). We also examine how the Bcl-2 family regulates other aspects of mitochondrial and ER physiology relevant to cell death.
Collapse
Affiliation(s)
- Xiaoke Chi
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - Justin Kale
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - Brian Leber
- Department of Medicine, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - David W Andrews
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8N 3Z5, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada; Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
| |
Collapse
|
41
|
Functions of the C-terminal domains of apoptosis-related proteins of the Bcl-2 family. Chem Phys Lipids 2014; 183:77-90. [PMID: 24892727 DOI: 10.1016/j.chemphyslip.2014.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 02/06/2023]
Abstract
Bcl-2 family proteins are involved in cell homeostasis, where they regulate cell death. Some of these proteins are pro-apoptotic and others pro-survival. Moreover, many of them share a similar domain composition with several of the so-called BH domains, although some only have a BH3 domain. A C-terminal domain is present in all the multi-BH domain proteins and in some of the BH3-only ones. This C-terminal domain is hydrophobic or amphipathic, for which reason it was thought when they were discovered that they were membrane anchors. Although this is indeed one of their functions, it has since been observed that they may also serve as regulators of the function of some members of this family, such as Bax. They may also serve to recognize the target membrane of some of these proteins, which only after an apoptotic signal, are incorporated into a membrane. It has been shown that peptides that imitate the sequence of C-terminal domains can form pores and may serve as a model to design cytotoxic molecules.
Collapse
|
42
|
Zhao YX, Cui M, Chen SF, Dong Q, Liu XY. Amelioration of ischemic mitochondrial injury and Bax-dependent outer membrane permeabilization by Mdivi-1. CNS Neurosci Ther 2014; 20:528-38. [PMID: 24712408 DOI: 10.1111/cns.12266] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 03/10/2014] [Accepted: 03/10/2014] [Indexed: 01/11/2023] Open
Abstract
AIMS Disturbance of the balance between mitochondrial fission and fusion has been implicated in cerebral ischemia and several neurodegenerative diseases, whereas the underlying mechanisms remain poorly understood. In the present study, we attempted to investigate the role of dynamin-related protein 1 (Drp1), a key mitochondrial fission protein, in the pathogenesis of cerebral ischemia. METHODS Using Drp1 siRNA or Mdivi-1, a small molecule inhibitor of Drp1, we examined the effect of Drp1 knockdown or inhibition on oxygen-glucose deprivation (OGD)-induced mitochondrial dysfunction and death of SH-SY-5Y cells. Cell death and viability were evaluated with LDH and MTT assays, respectively, and mitochondrial morphology, mitochondrial membrane potential (Δψm), and ATP production were assessed using epifluorescence microscopy, flow cytometry, and HPLC, respectively. Moreover, to examine the effect of Drp1 inhibition on ischemic brain injury, middle cerebral artery occlusion (MCAO) mice were injected (i.p.) with Mdivi1, and blood-brain barrier permeability, brain water content, and cell apoptosis were assessed. RESULTS Knockdown or inhibition of Drp1 by Mdivi-1 significantly attenuated OGD-induced cell death in SH-SY-5Y cells, associated with reduced morphological change of mitochondria and attenuated Bax insertion,oligomerization. Moreover, treatment of the MCAO mice with Mdivi-1 remarkably reduced the infarct volume and neurological deficits in a dose-dependent manner, associated with marked reduction of mitochondrial fragmentation and BAX expression. CONCLUSIONS Down-regulation or inhibition of Drp1 may reduce cerebral ischemic damage through maintaining normal mitochondrial morphology and function, and decreasing Bax insertion and oligomerization in mitochondria.
Collapse
Affiliation(s)
- Yan-Xin Zhao
- Department of Neurology, The 10th People's Hospital, Tongji University, Shanghai, China
| | | | | | | | | |
Collapse
|
43
|
Matissek KJ, Okal A, Mossalam M, Lim CS. Delivery of a monomeric p53 subdomain with mitochondrial targeting signals from pro-apoptotic Bak or Bax. Pharm Res 2014; 31:2503-15. [PMID: 24633417 DOI: 10.1007/s11095-014-1346-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 02/24/2014] [Indexed: 12/12/2022]
Abstract
PURPOSE p53 targeted to the mitochondria is the fastest and most direct pathway for executing p53 death signaling. The purpose of this work was to determine if mitochondrial targeting signals (MTSs) from pro-apoptotic Bak and Bax are capable of targeting p53 to the mitochondria and inducing rapid apoptosis. METHODS p53 and its DNA-binding domain (DBD) were fused to MTSs from Bak (p53-BakMTS, DBD-BakMTS) or Bax (p53-BaxMTS, DBD-BaxMTS). Mitochondrial localization was tested via fluorescence microscopy in 1471.1 cells, and apoptosis was detected via 7-AAD in breast (T47D), non-small cell lung (H1373), ovarian (SKOV-3) and cervical (HeLa) cancer cells. To determine that apoptosis is via the intrinsic apoptotic pathway, TMRE and caspase-9 assays were conducted. Finally, the involvement of p53/Bak specific pathway was tested. RESULTS MTSs from Bak and Bax are capable of targeting p53 to the mitochondria, and p53-BakMTS and p53-BaxMTS cause apoptosis through the intrinsic apoptotic pathway. Additionally, p53-BakMTS, DBD-BakMTS, p53-BaxMTS and DBD-BaxMTS caused apoptosis in T47D, H1373, SKOV-3 and HeLa cells. The apoptotic mechanism of p53-BakMTS and DBD-BakMTS was Bak dependent. CONCLUSION Our data demonstrates that p53-BakMTS (or BaxMTS) and DBD-BakMTS (or BaxMTS) cause apoptosis at the mitochondria and can be used as a potential gene therapeutic in cancer.
Collapse
Affiliation(s)
- Karina J Matissek
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah, USA
| | | | | | | |
Collapse
|
44
|
Fröhlich M, Dejanovic B, Kashkar H, Schwarz G, Nussberger S. S-palmitoylation represents a novel mechanism regulating the mitochondrial targeting of BAX and initiation of apoptosis. Cell Death Dis 2014; 5:e1057. [PMID: 24525733 PMCID: PMC3944235 DOI: 10.1038/cddis.2014.17] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 12/23/2013] [Accepted: 01/02/2014] [Indexed: 12/19/2022]
Abstract
The intrinsic pathway of apoptotic cell death is mainly mediated by the BCL-2-associated X (BAX) protein through permeabilization of the mitochondrial outer membrane (MOM) and the concomitant release of cytochrome c into the cytosol. In healthy, non-apoptotic cells, BAX is predominantly localized in the cytosol and exhibits a dynamic shuttle cycle between the cytosol and the mitochondria. Thus, the initial association with mitochondria represents a critical regulatory step enabling BAX to insert into MOMs, promoting the release of cytochrome c and ultimately resulting in apoptosis. However, the molecular mode of how BAX associates with MOMs and whether a cellular regulatory mechanism governs this process is poorly understood. Here we show that in both primary tissues and cultured cells, the association with MOMs and the proapoptotic action of BAX is controlled by its S-palmitoylation at Cys-126. A lack of BAX palmitoylation reduced BAX mitochondrial translocation, BAX oligomerization, caspase activity and apoptosis. Furthermore, ectopic expression of specific palmitoyl transferases in cultured healthy cells increases BAX S-palmitoylation and accelerates apoptosis, whereas malignant tumor cells show reduced BAX S-palmitoylation consistent with their reduced BAX-mediated proapoptotic activity. Our findings suggest that S-palmitoylation of BAX at Cys126 is a key regulatory process of BAX-mediated apoptosis.
Collapse
Affiliation(s)
- M Fröhlich
- Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany
| | - B Dejanovic
- Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany
| | - H Kashkar
- Institute for Medical Microbiology, Immunology and Hygiene and Center for Molecular Medicine, Cologne University, Goldenfels Strasse 19-21, Cologne 50935, Germany
| | - G Schwarz
- Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany
| | - S Nussberger
- 1] Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany [2] Biophysics Department, Institute of Biology, University of Stuttgart, Pfaffenwaldring 57, Stuttgart 70550, Germany
| |
Collapse
|
45
|
Evaluation of Bax and Bak gene mutations and expression in breast cancer. BIOMED RESEARCH INTERNATIONAL 2014; 2014:249372. [PMID: 24672785 PMCID: PMC3933335 DOI: 10.1155/2014/249372] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 11/11/2013] [Indexed: 02/07/2023]
Abstract
Genetic analyses have provided evidence to suggest that Bax and Bak are the essential genes for apoptosis in mammalians cells. This study aimed to search for biomarkers in breast cancer to be used as prognostic markers for the disease. The Bak and Bax genes expressions were analyzed in 23 breast cancer patients by RT-PCR technique. SSCP technique was used to detect the mobility of the abnormal fragment in Bak exon 4. PCR for Bax promoter was digested with Tau 1 restriction enzyme to identify a single polymorphism G(-248)A. The expression of Bak gene is related to several clinical factors of breast cancer. The analysis of Bax RNA showed 4 isoforms of Bax with different distributions in the normal and tumor tissues. These isoforms were Bax α, d, δ, and ζ. Exon 4 had a normal pattern in all cases of breast cancer. There was a statistically significant difference in the frequency distribution of the G(-248)A genotypes in the breast cancer tissues with grade 3+high, T2 stage, lobular +other, and PR −ve subgroups. In this study, Bak expression seems to lead to development of breast cancer and affects the disease progression. Also, Bax d and Bax δ could be used as risk factor and biomarker for breast cancer with the distribution of G284A.
Collapse
|
46
|
Lindenboim L, Sasson T, Worman HJ, Borner C, Stein R. Cellular stress induces Bax-regulated nuclear bubble budding and rupture followed by nuclear protein release. Nucleus 2014; 5:527-41. [PMID: 25482068 PMCID: PMC4615202 DOI: 10.4161/19491034.2014.970105] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 07/31/2014] [Accepted: 09/15/2014] [Indexed: 11/19/2022] Open
Abstract
Cellular stress triggers many pathways including nuclear protein redistribution. We previously discovered that this process is regulated by Bax but the underlying mechanism has not yet been studied. Here we define this mechanism by showing that apoptotic stimuli cause Bax-regulated disturbances in lamin A/C and nuclear envelope (NE)-associated proteins which results in the generation and subsequent rupture of nuclear protein-containing bubbles. The bubbles do not contain DNA and are encapsulated by impaired nuclear pore-depleted NE. Stress-induced generation and rupture of nuclear bubbles ultimately leads to the discharge of nuclear proteins into the cytoplasm. This process precedes morphological changes of apoptosis and occurs independently of caspases. Rescue experiments revealed that this Bax effect is non-canonical, i.e. it requires the BH3 domain and α-helices 5 and 6 but it is not inhibited by Bcl(-)xL. Targeting Bax to the NE by the Klarsicht/ANC-1/Syne-1 homology (KASH) domain effectively triggers the generation and rupture of nuclear bubbles. Overall, our findings provide evidence for a novel stress-response, which is regulated by a non-canonical action of Bax on the NE.
Collapse
Key Words
- Bax
- Bax/Bak, Bax and Bak
- DKO, double knockout
- INM, inner nuclear membrane
- KASH, Klarsicht: ANC-1, Syne homology
- LAP, lamina-associated polypeptide
- LINC, links nucleoskeleton and cytoskeleton
- MEFs, mouse embryonic fibroblasts
- MOMP, mitochondrial outer membrane permeabilization
- NE, nuclear envelope
- NPCs, nuclear pore complexes
- NPM, nucleophosmin
- NPR, nuclear protein redistribution
- ONM, outer nuclear membrane
- PI, propidium iodide
- Q-VD-OPH, quinoline-Val-Asp(OMe)-CH2-OPH.
- SIGRUNB, stress-induced generation and rupture of nuclear bubbles
- apoptosis
- lamin
- nuclear envelope
- nucleus
Collapse
Affiliation(s)
- Liora Lindenboim
- Department of Neurobiology; George S. Wise Faculty of Life Sciences; Tel Aviv University; Ramat Aviv, Israel
| | - Tiki Sasson
- Department of Neurobiology; George S. Wise Faculty of Life Sciences; Tel Aviv University; Ramat Aviv, Israel
| | - Howard J Worman
- Department of Medicine and Department of Pathology and Cell Biology; College of Physicians and Surgeons; Columbia University; New York, NY, USA
| | - Christoph Borner
- Institute of Molecular Medicine and Cell Research; Albert Ludwigs University Freiburg; Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM); Albert Ludwigs University Freiburg; Freiburg, Germany
- Excellence Cluster, Centre for Biological Signaling Studies (BIOSS); Albert Ludwigs University Freiburg; Freiburg, Germany
| | - Reuven Stein
- Department of Neurobiology; George S. Wise Faculty of Life Sciences; Tel Aviv University; Ramat Aviv, Israel
| |
Collapse
|
47
|
Lindenboim L, Ferrando-May E, Borner C, Stein R. Non-canonical function of Bax in stress-induced nuclear protein redistribution. Cell Mol Life Sci 2013; 70:3013-27. [PMID: 23475110 PMCID: PMC11113441 DOI: 10.1007/s00018-013-1306-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 02/13/2013] [Accepted: 02/18/2013] [Indexed: 10/27/2022]
Abstract
Bax and Bak (Bax/Bak) are essential pro-apoptotic proteins of the Bcl-2 family that trigger mitochondrial outer membrane permeabilization (MOMP) in a Bcl-2/Bcl-xL-inhibitable manner. We recently discovered a new stress-related function for Bax/Bak-regulation of nuclear protein redistribution (NPR) from the nucleus to cytoplasm. This effect was independent of Bax/Bak N-terminus exposure and not inhibited by Bcl-xL over-expression. Here, we studied the molecular mechanism governing this novel non-canonical response. Wild-type (WT) and mutant versions of Bax were re-expressed in Bax/Bak double-knockout mouse embryonic fibroblasts and their ability to promote NPR, apoptotic events, and changes in lamin A mobility was examined. Our results show that, in this system, Bax expression was sufficient to restore NPR such as in WT cells undergoing apoptosis. This activity of Bax was uncoupled from cytochrome c release from the mitochondria (indicative of MOMP) and required its membrane localization, α helices 5/6, and the Bcl-2 homology 3 (BH3) domain. Moreover, enrichment of Bax in the nuclear envelope by the so-called Klarsicht/ANC-1/Syne-1 homology domain effectively triggered NPR as in WT Bax, but without inducing MOMP or cell death. Bax-induced NPR was associated with impairment in lamin A mobility, implying a connection between these two nuclear envelope-associated events. Overall, the results indicate a new MOMP-independent, stress-induced Bax function on the nuclear envelope.
Collapse
Affiliation(s)
- Liora Lindenboim
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Ramat Aviv, Israel
| | - Elisa Ferrando-May
- Department of Biology, Bioimaging Center, University of Konstanz, 78457 Constance, Germany
| | - Christoph Borner
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University Freiburg, Stefan Meier Strasse 17, 79104 Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, Albertstrasse 19a, 79104 Freiburg, Germany
- Excellence Cluster, Centre for Biological Signaling Studies (BIOSS), Albert Ludwigs University Freiburg, Hebelstrasse 25, 79104 Freiburg, Germany
| | - Reuven Stein
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Ramat Aviv, Israel
| |
Collapse
|
48
|
Schellenberg B, Wang P, Keeble JA, Rodriguez-Enriquez R, Walker S, Owens TW, Foster F, Tanianis-Hughes J, Brennan K, Streuli CH, Gilmore AP. Bax exists in a dynamic equilibrium between the cytosol and mitochondria to control apoptotic priming. Mol Cell 2013; 49:959-71. [PMID: 23375500 PMCID: PMC3594749 DOI: 10.1016/j.molcel.2012.12.022] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 11/02/2012] [Accepted: 12/20/2012] [Indexed: 12/19/2022]
Abstract
The proapoptotic Bcl-2 protein Bax is predominantly found in the cytosol of nonapoptotic cells and is commonly thought to translocate to mitochondria following an apoptotic stimulus. The current model for Bax activation is that BH3 proteins bind to cytosolic Bax, initiating mitochondrial targeting and outer-membrane permeabilization. Here, we challenge this and show that Bax is constitutively targeted to mitochondria but in nonapoptotic cells is constantly translocated back to the cytosol. Using live-cell spinning-disk confocal imaging with a combination of FLIP, FRAP, and photoactivatable GFP-Bax, we demonstrate that disrupting adhesion-dependent survival signals slows the rate of Bax’s dissociation from mitochondria, leading to its accumulation on the outer mitochondrial membrane. The overall accumulation of mitochondrial Bax following loss of survival signaling sensitizes cells to proapoptotic BH3 proteins. Our findings show that Bax is normally in a dynamic equilibrium between cytosol and mitochondria, enabling fluctuations in survival signals to finely adjust apoptotic sensitivity.
Collapse
Affiliation(s)
- Barbara Schellenberg
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Gowda PS, Zhou F, Chadwell LV, McEwen DG. p53 binding prevents phosphatase-mediated inactivation of diphosphorylated c-Jun N-terminal kinase. J Biol Chem 2012; 287:17554-17567. [PMID: 22467874 DOI: 10.1074/jbc.m111.319277] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
c-Jun N-terminal kinase (JNK) is a serine/threonine phosphotransferase whose sustained activation in response to genotoxic stress promotes apoptosis. In Drosophila, the normally rapid JNK-dependent apoptotic response to genotoxic stress is significantly delayed in Dmp53 (Drosophila p53) mutants. Likewise, the extent of JNK activity after UV irradiation is dependent on p53 in murine embryonic fibroblasts with loss of p53 resulting in diminished JNK activity. Together, these results suggest that p53 potentiates the JNK-dependent response to genotoxic stress; however, the mechanism whereby p53 stimulates JNK activity remains undefined. Here, we demonstrate that both Drosophila and human p53 can directly stimulate JNK activity independently of p53-dependent gene transcription. Furthermore, we demonstrate that both the Drosophila and human p53 orthologs form a physical complex with diphosphorylated JNK ((DP)JNK) both in vivo and in vitro, suggesting that the interaction is evolutionarily conserved. Focusing on human p53, we demonstrate that the interaction maps to the DNA binding domain (hp53(DBD)). Intriguingly, binding of p53(DBD) alone to (DP)JNK prevented its inactivation by MAPK phosphatase (MKP)-5; however, JNK was still able to phosphorylate c-Jun while in a complex with the p53(DBD). Apparent dissociation constants for the p53(DBD)·(DP)JNK (274 ± 14 nm) and MKP-5·(DP)JNK (55 ± 8 nm) complexes were established; however, binding of MKP-5 and p53 to JNK was not mutually exclusive. Together, these results suggest that stress-dependent increases in p53 levels potentiate JNK activation by preventing its rapid dephosphorylation by MKPs and that the simultaneous activation of p53 and JNK may constitute a "fail-safe" switch for the JNK-dependent apoptotic response.
Collapse
Affiliation(s)
- Pramod S Gowda
- Departments of Biochemistry and The University of Texas Health Science Center, San Antonio, Texas 78229
| | - Fuchun Zhou
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center, San Antonio, Texas 78229; Department of Pediatrics and The University of Texas Health Science Center, San Antonio, Texas 78229
| | - Linda V Chadwell
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center, San Antonio, Texas 78229
| | - Donald G McEwen
- Departments of Biochemistry and The University of Texas Health Science Center, San Antonio, Texas 78229; Greehey Children's Cancer Research Institute, The University of Texas Health Science Center, San Antonio, Texas 78229.
| |
Collapse
|
50
|
Ferrer PE, Frederick P, Gulbis JM, Dewson G, Kluck RM. Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function. PLoS One 2012; 7:e31510. [PMID: 22442658 PMCID: PMC3307716 DOI: 10.1371/journal.pone.0031510] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 01/11/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND One of two proapoptotic Bcl-2 proteins, Bak or Bax, is required to permeabilize the mitochondrial outer membrane during apoptosis. While Bax is mostly cytosolic and translocates to mitochondria following an apoptotic stimulus, Bak is constitutively integrated within the outer membrane. Membrane anchorage occurs via a C-terminal transmembrane domain that has been studied in Bax but not in Bak, therefore what governs their distinct subcellular distribution is uncertain. In addition, whether the distinct subcellular distributions of Bak and Bax contributes to their differential regulation during apoptosis remains unclear. METHODOLOGY/PRINCIPAL FINDINGS To gain insight into Bak and Bax targeting to mitochondria, elements of the Bak C-terminus were mutated, or swapped with those of Bax. Truncation of the C-terminal six residues (C-segment) or substitution of three basic residues within the C-segment destabilized Bak. Replacing the Bak C-segment with that from Bax rescued stability and function, but unexpectedly resulted in a semi-cytosolic protein, termed Bak/BaxCS. When in the cytosol, both Bax and Bak/BaxCS sequestered their hydrophobic transmembrane domains in their hydrophobic surface groove. Upon apoptotic signalling, Bak/BaxCS translocated to the mitochondrial outer membrane, inserted its transmembrane domain, oligomerized, and released cytochrome c. Despite this Bax-like subcellular distribution, Bak/BaxCS retained Bak-like regulation following targeting of Mcl-1. CONCLUSIONS/SIGNIFICANCE Residues in the C-segment of Bak and of Bax contribute to their distinct subcellular localizations. That a semi-cytosolic form of Bak, Bak/BaxCS, could translocate to mitochondria and release cytochrome c indicates that Bak and Bax share a conserved mode of activation. In addition, the differential regulation of Bak and Bax by Mcl-1 is predominantly independent of the initial subcellular localizations of Bak and Bax.
Collapse
Affiliation(s)
- Pedro Eitz Ferrer
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Paul Frederick
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Jacqueline M. Gulbis
- 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
- * E-mail:
| |
Collapse
|