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Li Y, Zhao R, Xiu Z, Yang X, Zhu Y, Han J, Li S, Li Y, Sun L, Li X, Jin N, Li Y. Neobavaisoflavone induces pyroptosis of liver cancer cells via Tom20 sensing the activated ROS signal. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 116:154869. [PMID: 37196512 DOI: 10.1016/j.phymed.2023.154869] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 04/27/2023] [Accepted: 05/08/2023] [Indexed: 05/19/2023]
Abstract
BACKGROUND Neobavaisoflavone (NBIF), a natural active ingredient isolated from Psoralea, possesses anti-inflammatory, anti-cancer, and antioxidant properties; however, the anti-tumor mechanism of NBIF has not been thoroughly investigated, and the inhibitory effect and inhibitory pathway of NBIF on liver cancer are still unknown. PURPOSE Our study aimed to explore the effects of NBIF on hepatocellular carcinoma and its potential mechanisms. METHODS First, we detected the inhibition of NBIF on HCC cells by the CCK8 assay and then observed the morphological changes of the cells under the microscope. Besides, we analyzed the changes in the pyroptosis level of NBIF when inhibiting the cells through flow cytometry, immunofluorescence, and a western blot assay. Finally, we used a mouse tumor-bearing model to explore the effects of NBIF in vivo on HCCLM3 cells. RESULTS NBIF-treated HCC cells exhibited specific features of pyroptosis. Analysis of pyroptosis-related protein levels revealed that NBIF primarily induced pyroptosis in HCC cells via the caspase-3-GSDME signaling pathway. Then, we demonstrated that NBIF impacted the protein expression of Tom20 by producing ROS in HCC cells, hence promoting the recruitment of Bax to mitochondria, activating caspase-3, cutting GSDME, and triggering pyroptosis. CONCLUSIONS By activating ROS, NBIF was able to trigger pyroptosis in HCC cells, providing an experimental basis for the future study of new treatments for liver cancer.
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Affiliation(s)
- Yaru Li
- Medical College, Yanbian University, Yanji, 133002, PR China
| | - Renshuang Zhao
- Medical College, Yanbian University, Yanji, 133002, PR China
| | - Zhiru Xiu
- Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China
| | - Xia Yang
- Medical College, Yanbian University, Yanji, 133002, PR China
| | - Yilong Zhu
- Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China
| | - Jicheng Han
- Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China; Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, 130122, PR China
| | - Shanzhi Li
- Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China
| | - Yue Li
- Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China
| | - Lili Sun
- Medical College, Yanbian University, Yanji, 133002, PR China
| | - Xiao Li
- Medical College, Yanbian University, Yanji, 133002, PR China; Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China; Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, 130122, PR China.
| | - Ningyi Jin
- Medical College, Yanbian University, Yanji, 133002, PR China; Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China; Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, 130122, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, PR China.
| | - Yiquan Li
- Medical College, Yanbian University, Yanji, 133002, PR China; Academician Workstation of Jilin Province, Changchun University of Chinese Medicine, Changchun, 130117, PR China.
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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.
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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.
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3
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Yadav S, Sawarni N, Kumari P, Sharma M. Advancement in analytical techniques fabricated for the quantitation of cytochrome c. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.09.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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4
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Wolf P, Schoeniger A, Edlich F. Pro-apoptotic complexes of BAX and BAK on the outer mitochondrial membrane. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119317. [PMID: 35752202 DOI: 10.1016/j.bbamcr.2022.119317] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/02/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
In multicellular organisms the regulated cell death apoptosis is critically important for both ontogeny and homeostasis. Mitochondria are indispensable for stress-induced apoptosis. The BCL-2 protein family controls mitochondrial apoptosis and initiates cell death through the pro-apoptotic activities of BAX and BAK at the outer mitochondrial membrane (OMM). Cellular survival is ensured by the retrotranslocation of mitochondrial BAX and BAK into the cytosol by anti-apoptotic BCL-2 proteins. BAX/BAK-dependent OMM permeabilization releases the mitochondrial cytochrome c (cyt c), which initiates activation of caspase-9. The caspase cascade leads to cell shrinkage, plasma membrane blebbing, chromatin condensation, and apoptotic body formation. Although it is clear that ultimately complexes of active BAX and BAK commit the cell to apoptosis, the nature of these complexes is still enigmatic. Excessive research has described a range of complexes, varying from a few molecules to several 10,000, in different systems. BAX/BAK complexes potentially form ring-like structures that could expose the inner mitochondrial membrane. It has been suggested that these pores allow the efflux of small proteins and even mitochondrial DNA. Here we summarize the current state of knowledge for mitochondrial BAX/BAK complexes and the interactions between these proteins and the membrane.
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Affiliation(s)
- Philipp Wolf
- Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Axel Schoeniger
- Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Frank Edlich
- Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, 04103 Leipzig, Germany.
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5
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Wei X, Xie F, Zhou X, Wu Y, Yan H, Liu T, Huang J, Wang F, Zhou F, Zhang L. Role of pyroptosis in inflammation and cancer. Cell Mol Immunol 2022; 19:971-992. [PMID: 35970871 PMCID: PMC9376585 DOI: 10.1038/s41423-022-00905-x] [Citation(s) in RCA: 167] [Impact Index Per Article: 83.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 07/11/2022] [Indexed: 12/13/2022] Open
Abstract
Pyroptosis is a form of programmed cell death mediated by gasdermin and is a product of continuous cell expansion until the cytomembrane ruptures, resulting in the release of cellular contents that can activate strong inflammatory and immune responses. Pyroptosis, an innate immune response, can be triggered by the activation of inflammasomes by various influencing factors. Activation of these inflammasomes can induce the maturation of caspase-1 or caspase-4/5/11, both of which cleave gasdermin D to release its N-terminal domain, which can bind membrane lipids and perforate the cell membrane. Here, we review the latest advancements in research on the mechanisms of pyroptosis, newly discovered influencing factors, antitumoral properties, and applications in various diseases. Moreover, this review also provides updates on potential targeted therapies for inflammation and cancers, methods for clinical prevention, and finally challenges and future directions in the field.
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Bcl-2 Family Members and the Mitochondrial Import Machineries: The Roads to Death. Biomolecules 2022; 12:biom12020162. [PMID: 35204663 PMCID: PMC8961529 DOI: 10.3390/biom12020162] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 01/27/2023] Open
Abstract
The localization of Bcl-2 family members at the mitochondrial outer membrane (MOM) is a crucial step in the implementation of apoptosis. We review evidence showing the role of the components of the mitochondrial import machineries (translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM)) in the mitochondrial localization of Bcl-2 family members and how these machineries regulate the function of pro- and anti-apoptotic proteins in resting cells and in cells committed into apoptosis.
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7
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Doan KN, Grevel A, Mårtensson CU, Ellenrieder L, Thornton N, Wenz LS, Opaliński Ł, Guiard B, Pfanner N, Becker T. The Mitochondrial Import Complex MIM Functions as Main Translocase for α-Helical Outer Membrane Proteins. Cell Rep 2021; 31:107567. [PMID: 32348752 DOI: 10.1016/j.celrep.2020.107567] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/19/2020] [Accepted: 04/02/2020] [Indexed: 01/08/2023] Open
Abstract
The mitochondrial outer membrane contains integral proteins with α-helical membrane anchors or a transmembrane β-barrel. The translocase of the outer membrane (TOM) cooperates with the sorting and assembly machinery (SAM) in the import of β-barrel proteins, whereas the mitochondrial import (MIM) complex inserts precursors of multi-spanning α-helical proteins. Single-spanning proteins constitute more than half of the integral outer membrane proteins; however, their biogenesis is poorly understood. We report that the yeast MIM complex promotes the insertion of proteins with N-terminal (signal-anchored) or C-terminal (tail-anchored) membrane anchors. The MIM complex exists in three dynamic populations. MIM interacts with TOM to accept precursor proteins from the receptor Tom70. Free MIM complexes insert single-spanning proteins that are imported in a Tom70-independent manner. Finally, coupling of MIM and SAM promotes early assembly steps of TOM subunits. We conclude that the MIM complex is a major and versatile protein translocase of the mitochondrial outer membrane.
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Affiliation(s)
- Kim Nguyen Doan
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Alexander Grevel
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Christoph U Mårtensson
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Lars Ellenrieder
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Nicolas Thornton
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Lena-Sophie Wenz
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Łukasz Opaliński
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Bernard Guiard
- Centre de Génétique Moléculaire, CNRS, 91190 Gif-sur-Yvette, France
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
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5-Hydroxytryptamine Modulates Maturation and Mitochondria Function of Human Oligodendrocyte Progenitor M03-13 Cells. Int J Mol Sci 2021; 22:ijms22052621. [PMID: 33807720 PMCID: PMC7962057 DOI: 10.3390/ijms22052621] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 01/07/2023] Open
Abstract
Inside the adult CNS, oligodendrocyte progenitor cells (OPCS) are able to proliferate, migrate and differentiate into mature oligodendrocytes (OLs) which are responsible for the production of myelin sheet and energy supply for neurons. Moreover, in demyelinating diseases, OPCs are recruited to the lesion areas where they undergo differentiation and myelin synthesis. Serotonin (5-hydroxytryptamine, 5-HT) is involved in OLs’ development and myelination, but so far the molecular mechanisms involved or the effects of 5-HT on mitochondria function have not yet been well documented. Our data show that 5-HT inhibits migration and proliferation committing cells toward differentiation in an immortalized human oligodendrocyte precursor cell line, M03-13. Migration blockage is mediated by reactive oxygen species (ROS) generation since antioxidants, such as Vit C and Cu-Zn superoxide dismutase, prevent the inhibitory effects of 5-HT on cell migration. 5-HT inhibits OPC migration and proliferation and increases OL phenotypic markers myelin basic protein (MBP) and Olig-2 via protein kinase C (PKC) activation since the inhibitor of PKC, bis-indolyl-maleimide (BIM), counteracts 5-HT effects. NOX inhibitors as well, reverse the effects of 5-HT, indicating that 5-HT influences the maturation process of OPCs by NOX-dependent ROS production. Finally, 5-HT increases mitochondria function and antioxidant activity. The identification of the molecular mechanisms underlying the effects of 5-HT on maturation and energy metabolism of OPCs could pave the way for the development of new treatments for autoimmune demyelinating diseases such as Multiple Sclerosis where oligodendrocytes are the primary target of immune attack.
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9
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Gupta A, Becker T. Mechanisms and pathways of mitochondrial outer membrane protein biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148323. [PMID: 33035511 DOI: 10.1016/j.bbabio.2020.148323] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/26/2020] [Accepted: 09/29/2020] [Indexed: 11/29/2022]
Abstract
Outer membrane proteins integrate mitochondria into the cellular environment. They warrant exchange of small molecules like metabolites and ions, transport proteins into mitochondria, form contact sites to other cellular organelles for lipid exchange, constitute a signaling platform for apoptosis and inflammation and mediate organelle fusion and fission. The outer membrane contains two types of integral membrane proteins. Proteins with a transmembrane β-barrel structure and proteins with a single or multiple α-helical membrane spans. All outer membrane proteins are produced on cytosolic ribosomes and imported into the target organelle. Precursors of β-barrel and α-helical proteins are transported into the outer membrane via distinct import routes. The translocase of the outer membrane (TOM complex) transports β-barrel precursors across the outer membrane and the sorting and assembly machinery (SAM complex) inserts them into the target membrane. The mitochondrial import (MIM) complex constitutes the major integration site for α-helical embedded proteins. The import of some MIM-substrates involves TOM receptors, while others are imported in a TOM-independent manner. Remarkably, TOM, SAM and MIM complexes dynamically interact to import a large set of different proteins and to coordinate their assembly into protein complexes. Thus, protein import into the mitochondrial outer membrane involves a dynamic platform of protein translocases.
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Affiliation(s)
- Arushi Gupta
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
| | - Thomas Becker
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Universität Bonn, Nussallee 11, 53115 Bonn, Germany.
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Szekerczés T, Gógl A, Illyés I, Mandl J, Borka K, Kiss A, Schaff Z, Lendvai G, Werling K. Autophagy, Mitophagy and MicroRNA Expression in Chronic Hepatitis C and Autoimmune Hepatitis. Pathol Oncol Res 2020; 26:2143-2151. [PMID: 32124227 PMCID: PMC7471137 DOI: 10.1007/s12253-020-00799-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/11/2020] [Indexed: 12/13/2022]
Abstract
Although the role of autophagy has been implicated in several forms of chronic hepatitis, it is still not fully understood. Active autophagy eliminates damaged molecules and organelles (such as mitochondria) by lysosomal degradation. In the present study, we aimed to examine and compare autophagy activity in chronic hepatitis C (CHC) and autoimmune hepatitis (AIH) by detecting the expression of autophagy (LC3 and p62) and mitochondrium-related (TOMM20) proteins, as well as the levels of selected microRNAs (miR-101, -155, -204 and - 224) known to be involved in the regulation of autophagy. In addition, the expression levels were related to pathohistological parameters. Liver biopsy samples, including 45 CHC and 18 AIH cases, were immunohistochemically stained for LC3, p62 and TOMM20 and the expression of miRNAs was determined using real-time PCR. We found elevated LC3 and p62 in AIH samples as compared with CHC ones, indicating an activated autophagy that is impaired in AIH as no degradation of p62 seemed to occur. Moreover, p62 showed strong correlation with necroinflammatory grades in the AIH group. The observed elevated levels of TOMM20 and p62 suggest a less efficient elimination of damaged mitochondria in AIH as opposed to CHC, in which autophagy seems to have a more active function. The level of miR-101 was increased in case of CHC as compared with AIH, however, miR-155, -204 and 224 resulted in no expressional. Furthermore, miR-224 level correlated with steatosis and miR-155 expression with fibrosis stage in CHC. In conclusion, dissimilar autophagic activity was observed in CHC and AIH, suggesting a close association between impaired autophagy and severity of necroinflammation. This impairment may not be regulated by the analyzed miRNAs. Nevertheless, miR-224 and - 155 seem to be associated with CHC progression.
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MESH Headings
- Adolescent
- Adult
- Aged
- Autophagy
- Biomarkers, Tumor/genetics
- Disease Progression
- Female
- Follow-Up Studies
- Gene Expression Regulation, Neoplastic
- Hepatitis C, Chronic/genetics
- Hepatitis C, Chronic/metabolism
- Hepatitis C, Chronic/pathology
- Hepatitis C, Chronic/surgery
- Hepatitis, Autoimmune/genetics
- Hepatitis, Autoimmune/metabolism
- Hepatitis, Autoimmune/pathology
- Hepatitis, Autoimmune/surgery
- Humans
- Male
- MicroRNAs/genetics
- Middle Aged
- Mitophagy
- Prognosis
- Retrospective Studies
- Survival Rate
- Young Adult
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Affiliation(s)
- Tímea Szekerczés
- 2nd Department of Pathology, Semmelweis University, Üllői 93, 1091, Budapest, Hungary
| | - Alíz Gógl
- 2nd Department of Pathology, Semmelweis University, Üllői 93, 1091, Budapest, Hungary
| | - Ildikó Illyés
- 2nd Department of Pathology, Semmelweis University, Üllői 93, 1091, Budapest, Hungary
| | - József Mandl
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, 1094, Budapest, Hungary
| | - Katalin Borka
- 2nd Department of Pathology, Semmelweis University, Üllői 93, 1091, Budapest, Hungary
| | - András Kiss
- 2nd Department of Pathology, Semmelweis University, Üllői 93, 1091, Budapest, Hungary
| | - Zsuzsa Schaff
- 2nd Department of Pathology, Semmelweis University, Üllői 93, 1091, Budapest, Hungary
| | - Gábor Lendvai
- 2nd Department of Pathology, Semmelweis University, Üllői 93, 1091, Budapest, Hungary.
| | - Klára Werling
- 2nd Department of Internal Medicine, Semmelweis University, 1088, Budapest, Hungary
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Kreimendahl S, Rassow J. The Mitochondrial Outer Membrane Protein Tom70-Mediator in Protein Traffic, Membrane Contact Sites and Innate Immunity. Int J Mol Sci 2020; 21:E7262. [PMID: 33019591 PMCID: PMC7583919 DOI: 10.3390/ijms21197262] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 02/08/2023] Open
Abstract
Tom70 is a versatile adaptor protein of 70 kDa anchored in the outer membrane of mitochondria in metazoa, fungi and amoeba. The tertiary structure was resolved for the Tom70 of yeast, showing 26 α-helices, most of them participating in the formation of 11 tetratricopeptide repeat (TPR) motifs. Tom70 serves as a docking site for cytosolic chaperone proteins and co-chaperones and is thereby involved in the uptake of newly synthesized chaperone-bound proteins in mitochondrial biogenesis. In yeast, Tom70 additionally mediates ER-mitochondria contacts via binding to sterol transporter Lam6/Ltc1. In mammalian cells, TOM70 promotes endoplasmic reticulum (ER) to mitochondria Ca2+ transfer by association with the inositol-1,4,5-triphosphate receptor type 3 (IP3R3). TOM70 is specifically targeted by the Bcl-2-related protein MCL-1 that acts as an anti-apoptotic protein in macrophages infected by intracellular pathogens, but also in many cancer cells. By participating in the recruitment of PINK1 and the E3 ubiquitin ligase Parkin, TOM70 can be implicated in the development of Parkinson's disease. TOM70 acts as receptor of the mitochondrial antiviral-signaling protein (MAVS) and thereby participates in the corresponding system of innate immunity against viral infections. The protein encoded by Orf9b in the genome of SARS-CoV-2 binds to TOM70, probably compromising the synthesis of type I interferons.
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Affiliation(s)
| | - Joachim Rassow
- Institute for Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44801 Bochum, Germany;
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12
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Yan Z, Zhan J, Qi W, Lin J, Huang Y, Xue X, Pan X. The Protective Effect of Luteolin in Glucocorticoid-Induced Osteonecrosis of the Femoral Head. Front Pharmacol 2020; 11:1195. [PMID: 32903480 PMCID: PMC7435053 DOI: 10.3389/fphar.2020.01195] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/22/2020] [Indexed: 01/22/2023] Open
Abstract
Glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) is a frequently occurring type of nontraumatic osteonecrosis. A failure of the timely treatment can eventually result in the collapse of the subchondral bone structure. Luteolin (Lut), a compound extracted from Rhizoma Drynariae, is reported to possess multiple pharmacological properties including anticancer, antioxidant, antiapoptosis, and antiinflammatory properties. However, whether Lut has a protective effect on the development of GIONFH remains unclear. In this study, we evaluated the effect of Lut on Dexamethasone (Dex)-induced STAT1/caspase3 pathway in vitro and evaluated GIONFH model in vivo. In vitro, Lut inhibited the upregulation of Dex-induced phospho-STAT1, cleaved caspase9, and cleaved caspase3. In addition, Lut inhibited Dex-induced expression of Bax and cytochrome c and increased the expression of B cell lymphoma-2(Bcl-2). In vivo, Lut decreased the proportion of empty lacunae in rats with GIONFH. Taken together, these findings indicate that Lut may have therapeutic potential in the treatment of GIONFH. Further, this effect might be achieved by suppressing mitochondrial apoptosis of osteoblasts via inhibition of STAT1 activity.
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Affiliation(s)
- Zijian Yan
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Department of Orthopaedics, Zhejiang Provincial Key Laboratory of Orthpaedics, Wenzhou, China.,The Second School of Medicine, WenZhou Medical University, Wenzhou, China
| | - Jingdi Zhan
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Department of Orthopaedics, Zhejiang Provincial Key Laboratory of Orthpaedics, Wenzhou, China.,The Second School of Medicine, WenZhou Medical University, Wenzhou, China
| | - Weihui Qi
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Department of Orthopaedics, Zhejiang Provincial Key Laboratory of Orthpaedics, Wenzhou, China.,The Second School of Medicine, WenZhou Medical University, Wenzhou, China
| | - Jian Lin
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yijiang Huang
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xinghe Xue
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiaoyun Pan
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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Tachtsis B, Whitfield J, Hawley JA, Hoffman NJ. Omega-3 Polyunsaturated Fatty Acids Mitigate Palmitate-Induced Impairments in Skeletal Muscle Cell Viability and Differentiation. Front Physiol 2020; 11:563. [PMID: 32581844 PMCID: PMC7283920 DOI: 10.3389/fphys.2020.00563] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/07/2020] [Indexed: 12/15/2022] Open
Abstract
Accumulation of excess saturated free fatty acids such as palmitate (PAL) in skeletal muscle leads to reductions in mitochondrial integrity, cell viability and differentiation. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) counteract PAL-induced lipid accumulation. EPA and DHA, as well as the n-3 PUFA docosapentaenoic acid (DPA), may therefore mitigate PAL-induced lipotoxicity to promote skeletal muscle cell survival and differentiation. C2C12 myoblasts were treated with 50 μM EPA, DPA, or DHA in the absence or presence of 500 μM PAL for 16 h either prior to myoblast analysis or induction of differentiation. Myoblast viability and markers of apoptosis, endoplasmic reticulum (ER) stress and myotube differentiation capacity were investigated using fluorescence microscopy and immunoblotting. High-resolution respirometry was used to assess mitochondrial function and membrane integrity. PAL induced cell death via apoptosis and increased protein content of ER stress markers BiP and CHOP. EPA, DPA, and DHA co-treatment maintained cell viability, prevented PAL-induced apoptosis and attenuated PAL-induced increases in BiP, whereas only DPA prevented increases in CHOP. PAL subsequently reduced protein content of the differentiation marker myogenin and inhibited myotube formation, and all n-3 PUFAs promoted myotube formation in the presence of PAL. Furthermore, DPA prevented PAL-induced release of cytochrome c and maintained mitochondrial integrity. These findings demonstrate the n-3 PUFAs EPA, DPA and DHA elicit similar protective effects against PAL-induced impairments in muscle cell viability and differentiation. Mechanistically, the protective effects of DPA against PAL lipotoxicity are attributable in part to its ability to maintain mitochondrial respiratory capacity via mitigating PAL-induced loss of mitochondrial membrane integrity.
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Affiliation(s)
- Bill Tachtsis
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Jamie Whitfield
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - John A Hawley
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Nolan J Hoffman
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
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Parvalbumin expression in oligodendrocyte-like CG4 cells causes a reduction in mitochondrial volume, attenuation in reactive oxygen species production and a decrease in cell processes' length and branching. Sci Rep 2019; 9:10603. [PMID: 31332265 PMCID: PMC6646370 DOI: 10.1038/s41598-019-47112-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 07/11/2019] [Indexed: 12/11/2022] Open
Abstract
Forebrain glial cells - ependymal cells and astrocytes -acquire upon injury- a "reactive" phenotype associated with parvalbumin (PV) upregulation. Since free radicals, e.g. reactive oxygen species (ROS) play a role in the pathogenesis of multiple sclerosis, and that PV-upregulation in glial cells is inversely correlated with the level of oxidative stress, we hypothesized that PV-upregulation might also protect oligodendrocytes by decreasing ROS production. Lentiviral transduction techniques allowed for PV overexpression in CG4 oligodendrocyte progenitor cells (OPCs). Depending on the growth medium CG4 cells can be maintained in an OPC-like state, or induced to differentiate into an oligodendrocyte (OLG)-like phenotype. While increased levels of PV had no effect on cell proliferation and invasiveness in vitro, PV decreased the mitochondria volume in CG4 cell bodies, as well as the mitochondrial density in CG4 processes in both OPC-like and OLG-like states. In line with the PV-induced global decrease in mitochondrial volume, elevated PV levels reduced transcript levels of mitochondrial transcription factors involved in mitochondria biogenesis. In differentiated PV-overexpressing CG4 cells with a decreased mitochondrial volume, UV-induced ROS production was lower than in control CG4 cells hinting towards a possible role of PV in counteracting oxidative stress. Unexpectedly, PV also decreased the length of processes in undifferentiated CG4 cells and moreover diminished branching of differentiated CG4 cell processes, strongly correlated with the decreased density of mitochondria in CG4 cell processes. Thus besides conferring a protective role against oxidative stress, PV in a cell autonomous fashion additionally affects process' growth and branching in CG4 cells.
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15
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Vlaski-Lafarge M, Loncaric D, Perez L, Labat V, Debeissat C, Brunet de la Grange P, Rossignol R, Ivanovic Z, Bœuf H. Bioenergetic Changes Underline Plasticity of Murine Embryonic Stem Cells. Stem Cells 2019; 37:463-475. [PMID: 30599083 DOI: 10.1002/stem.2965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 11/13/2018] [Accepted: 12/03/2018] [Indexed: 12/19/2022]
Abstract
Murine embryonic stem cells (mESCs) are endowed by a time-dependent window of plasticity during their early commitment steps. Indeed, while mESCs deprived of leukemia inhibitory factor (LIF) for 24 hours revert to their naive pluripotent state after subsequent LIF readdition, cells deprived of LIF for 48 hours are no longer efficient in reverting, upon LIF addition, and undergo irreversible differentiation. We investigated undisclosed bioenergetic profiles of early mESC-derived committed cells versus their undifferentiated states in order to reveal specific bioenergetic changes associated with mESC plasticity. Multiparametric bioenergetic analysis revealed that pluripotent (+LIF) and reversibly committed cells (-LIF24h) are energetically flexible, depending on both oxidative phosphorylation (OXPHOS) and glycolysis. They exhibit high mitochondrial respiration in the presence of the main energetic substrates and can also rely on glycolysis in the presence of OXPHOS inhibitor. Inhibition of the glycolysis or mitochondrial respiration does not change drastically the expression of pluripotency genes, which remain well expressed. In addition, cells treated with these inhibitors keep their capacity to differentiate efficiently upon embryoid bodies formation. Transition from metabolically active mESCs to irreversibly committed cells is associated with a clear change in mitochondrial network morphology, to an increase of adenosine triphosphate (ATP) produced from glycolysis and a decline of ATP turnover and of the mitochondrial activity without change in the mitochondrial mass. Our study pointed that plasticity window of mESCs is associated with the bivalent energetic metabolism and potency to shift to glycolysis or OXPHOS on demand. LIF removal provokes glycolytic metabolic orientation and consecutive loss of the LIF-dependent reversion of cells to the pluripotent state. Stem Cells 2019;37:463-475.
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Affiliation(s)
- Marija Vlaski-Lafarge
- R&D Department, Etablissement Français du Sang Nouvelle-Aquitaine, Bordeaux, France.,Inserm/U1035, University of Bordeaux
| | - Darija Loncaric
- R&D Department, Etablissement Français du Sang Nouvelle-Aquitaine, Bordeaux, France.,Inserm/U1035, University of Bordeaux
| | - Laura Perez
- R&D Department, Etablissement Français du Sang Nouvelle-Aquitaine, Bordeaux, France
| | - Véronique Labat
- R&D Department, Etablissement Français du Sang Nouvelle-Aquitaine, Bordeaux, France.,Inserm/U1035, University of Bordeaux
| | - Christelle Debeissat
- R&D Department, Etablissement Français du Sang Nouvelle-Aquitaine, Bordeaux, France.,Inserm/U1035, University of Bordeaux
| | - Philippe Brunet de la Grange
- R&D Department, Etablissement Français du Sang Nouvelle-Aquitaine, Bordeaux, France.,Inserm/U1035, University of Bordeaux
| | | | - Zoran Ivanovic
- R&D Department, Etablissement Français du Sang Nouvelle-Aquitaine, Bordeaux, France.,Inserm/U1035, University of Bordeaux
| | - Hélène Bœuf
- Inserm/U1026, University of Bordeaux, Bordeaux, France
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16
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Martins VM, Fernandes TR, Lopes D, Afonso CB, Domingues MRM, Côrte-Real M, Sousa MJ. Contacts in Death: The Role of the ER-Mitochondria Axis in Acetic Acid-Induced Apoptosis in Yeast. J Mol Biol 2018; 431:273-288. [PMID: 30414966 DOI: 10.1016/j.jmb.2018.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/12/2018] [Accepted: 11/05/2018] [Indexed: 02/08/2023]
Abstract
Endoplasmic reticulum-mitochondria contact sites have been a subject of increasing scientific interest since the discovery that these structures are disrupted in several pathologies. Due to the emerging data that correlate endoplasmic reticulum-mitochondria contact sites function with known events of the apoptotic program, we aimed to dissect this interplay using our well-established model of acetic acid-induced apoptosis in Saccharomyces cerevisiae. Until recently, the only known tethering complex between ER and mitochondria in this organism was the ER-mitochondria encounter structure (ERMES). Following our results from a screening designed to identify genes whose deletion rendered cells with an altered sensitivity to acetic acid, we hypothesized that the ERMES complex could be involved in cell death mediated by this stressor. Herein we demonstrate that single ablation of the ERMES components Mdm10p, Mdm12p and Mdm34p increases the resistance of S. cerevisiae to acetic acid-induced apoptosis, which is associated with a prominent delay in the appearance of several apoptotic markers. Moreover, abrogation of Mdm10p or Mdm34p abolished cytochrome c release from mitochondria. Since these two proteins are embedded in the mitochondrial outer membrane, we propose that the ERMES complex plays a part in cytochrome c release, a key event of the apoptotic cascade. In all, these findings will aid in targeted therapies for diseases where apoptosis is disrupted, as well as assist in the development of acetic acid-resistant strains for industrial processes.
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Affiliation(s)
- Vítor M Martins
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
| | - Tânia R Fernandes
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Diana Lopes
- Mass Spectrometry Centre, Department of Chemistry & QOPNA, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal; Department of Chemistry & CESAM & ECOMARE, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Catarina B Afonso
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Maria R M Domingues
- Mass Spectrometry Centre, Department of Chemistry & QOPNA, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal; Department of Chemistry & CESAM & ECOMARE, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Manuela Côrte-Real
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Maria J Sousa
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
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17
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Zhou B, Zhang JY, Liu XS, Chen HZ, Ai YL, Cheng K, Sun RY, Zhou D, Han J, Wu Q. Tom20 senses iron-activated ROS signaling to promote melanoma cell pyroptosis. Cell Res 2018; 28:1171-1185. [PMID: 30287942 PMCID: PMC6274649 DOI: 10.1038/s41422-018-0090-y] [Citation(s) in RCA: 345] [Impact Index Per Article: 57.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/20/2018] [Accepted: 08/22/2018] [Indexed: 12/27/2022] Open
Abstract
Iron has been shown to trigger oxidative stress by elevating reactive oxygen species (ROS) and to participate in different modes of cell death, such as ferroptosis, apoptosis and necroptosis. However, whether iron-elevated ROS is also linked to pyroptosis has not been reported. Here, we demonstrate that iron-activated ROS can induce pyroptosis via a Tom20-Bax-caspase-GSDME pathway. In melanoma cells, iron enhanced ROS signaling initiated by CCCP, causing the oxidation and oligomerization of the mitochondrial outer membrane protein Tom20. Bax is recruited to mitochondria by oxidized Tom20, which facilitates cytochrome c release to cytosol to activate caspase-3, eventually triggering pyroptotic death by inducing GSDME cleavage. Therefore, ROS acts as a causative factor and Tom20 senses ROS signaling for iron-driven pyroptotic death of melanoma cells. Since iron activates ROS for GSDME-dependent pyroptosis induction and melanoma cells specifically express a high level of GSDME, iron may be a potential candidate for melanoma therapy. Based on the functional mechanism of iron shown above, we further demonstrate that iron supplementation at a dosage used in iron-deficient patients is sufficient to maximize the anti-tumor effect of clinical ROS-inducing drugs to inhibit xenograft tumor growth and metastasis of melanoma cells through GSDME-dependent pyroptosis. Moreover, no obvious side effects are observed in the normal tissues and organs of mice during the combined treatment of clinical drugs and iron. This study not only identifies iron as a sensitizer amplifying ROS signaling to drive pyroptosis, but also implicates a novel iron-based intervention strategy for melanoma therapy.
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Affiliation(s)
- Bo Zhou
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Jia-Yuan Zhang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Xian-Shuo Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Hang-Zi Chen
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Yuan-Li Ai
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Kang Cheng
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Ru-Yue Sun
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Dawang Zhou
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Jiahuai Han
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Qiao Wu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China.
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18
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Martin-Sanchez D, Gallegos-Villalobos A, Fontecha-Barriuso M, Carrasco S, Sanchez-Niño MD, Lopez-Hernandez FJ, Ruiz-Ortega M, Egido J, Ortiz A, Sanz AB. Deferasirox-induced iron depletion promotes BclxL downregulation and death of proximal tubular cells. Sci Rep 2017; 7:41510. [PMID: 28139717 PMCID: PMC5282523 DOI: 10.1038/srep41510] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/21/2016] [Indexed: 12/21/2022] Open
Abstract
Iron deficiency has been associated with kidney injury. Deferasirox is an oral iron chelator used to treat blood transfusion-related iron overload. Nephrotoxicity is the most serious and common adverse effect of deferasirox and may present as an acute or chronic kidney disease. However, scarce data are available on the molecular mechanisms of nephrotoxicity. We explored the therapeutic modulation of deferasirox-induced proximal tubular cell death in culture. Deferasirox induced dose-dependent tubular cell death and AnexxinV/7AAD staining showed features of apoptosis and necrosis. However, despite inhibiting caspase-3 activation, the pan-caspase inhibitor zVAD-fmk failed to prevent deferasirox-induced cell death. Moreover, zVAD increased deferasirox-induced cell death, a feature sometimes found in necroptosis. Electron microscopy identified mitochondrial injury and features of necrosis. However, neither necrostatin-1 nor RIP3 knockdown prevented deferasirox-induced cell death. Deferasirox caused BclxL depletion and BclxL overexpression was protective. Preventing iron depletion protected from BclxL downregulation and deferasirox cytotoxicity. In conclusion, deferasirox promoted iron depletion-dependent cell death characterized by BclxL downregulation. BclxL overexpression was protective, suggesting a role for BclxL downregulation in iron depletion-induced cell death. This information may be used to develop novel nephroprotective strategies. Furthermore, it supports the concept that monitoring kidney tissue iron depletion may decrease the risk of deferasirox nephrotoxicity.
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Affiliation(s)
- Diego Martin-Sanchez
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Angel Gallegos-Villalobos
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Miguel Fontecha-Barriuso
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Susana Carrasco
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Maria Dolores Sanchez-Niño
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Francisco J Lopez-Hernandez
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
- Biomedical Research Institute of Salamanca, University of Salamanca, Salamanca, Spain
| | - Marta Ruiz-Ortega
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Jesus Egido
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
| | - Alberto Ortiz
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Ana Belén Sanz
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
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19
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Abstract
Mitochondria have to import the vast majority of their proteins, which are synthesized as precursors on cytosolic ribosomes. The translocase of the outer membrane (TOM complex) forms the general entry gate for the precursor proteins, which are subsequently sorted by protein machineries into the mitochondrial subcompartments: the outer and inner membrane, the intermembrane space and the mitochondrial matrix. The transport across and into the inner membrane is driven by the membrane potential, which is generated by the respiratory chain. Recent studies revealed that the lipid composition of mitochondrial membranes is important for the biogenesis of mitochondrial proteins. Cardiolipin and phosphatidylethanolamine exhibit unexpectedly specific functions for the activity of distinct protein translocases. Both phospholipids are required for full activity of respiratory chain complexes and thus to maintain the membrane potential for protein import. In addition, cardiolipin is required to maintain structural integrity of mitochondrial protein translocases. Finally, the low sterol content in the mitochondrial outer membrane may contribute to the targeting of some outer membrane proteins with a single α-helical membrane anchor. Altogether, mitochondrial lipids modulate protein import on various levels involving precursor targeting, membrane potential generation, stability and activity of protein translocases.
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20
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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: 20] [Impact Index Per Article: 2.5] [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.
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21
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Abstract
Permeabilization of the outer mitochondrial membrane that leads to the release of cytochrome c and several other apoptogenic proteins from mitochondria into cytosol represents a commitment point of apoptotic pathway in mammalian cells. This crucial event is governed by proteins of the Bcl-2 family. Molecular mechanisms, by which Bcl-2 family proteins permeabilize mitochondrial membrane, remain under dispute. Although yeast does not have apparent homologues of these proteins, when mammalian members of Bcl-2 family are expressed in yeast, they retain their activity, making yeast an attractive model system, in which to study their action. This review focuses on using yeast expressing mammalian proteins of the Bcl-2 family as a tool to investigate mechanisms, by which these proteins permeabilize mitochondrial membranes, mechanisms, by which pro- and antiapoptotic members of this family interact, and involvement of other cellular components in the regulation of programmed cell death by Bcl-2 family proteins.
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Affiliation(s)
- Peter Polčic
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic
| | - Petra Jaká
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic
| | - Marek Mentel
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic
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22
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Höhr AIC, Straub SP, Warscheid B, Becker T, Wiedemann N. Assembly of β-barrel proteins in the mitochondrial outer membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:74-88. [PMID: 25305573 DOI: 10.1016/j.bbamcr.2014.10.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/25/2014] [Accepted: 10/01/2014] [Indexed: 12/15/2022]
Abstract
Mitochondria evolved through endosymbiosis of a Gram-negative progenitor with a host cell to generate eukaryotes. Therefore, the outer membrane of mitochondria and Gram-negative bacteria contain pore proteins with β-barrel topology. After synthesis in the cytosol, β-barrel precursor proteins are first transported into the mitochondrial intermembrane space. Folding and membrane integration of β-barrel proteins depend on the mitochondrial sorting and assembly machinery (SAM) located in the outer membrane, which is related to the β-barrel assembly machinery (BAM) in bacteria. The SAM complex recognizes β-barrel proteins by a β-signal in the C-terminal β-strand that is required to initiate β-barrel protein insertion into the outer membrane. In addition, the SAM complex is crucial to form membrane contacts with the inner mitochondrial membrane by interacting with the mitochondrial contact site and cristae organizing system (MICOS) and shares a subunit with the endoplasmic reticulum-mitochondria encounter structure (ERMES) that links the outer mitochondrial membrane to the endoplasmic reticulum (ER).
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Affiliation(s)
- Alexandra I C Höhr
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
| | - Sebastian P Straub
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany; Abteilung Biochemie und Funktionelle Proteomik, Institut für Biologie II, Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
| | - Thomas Becker
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany
| | - Nils Wiedemann
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany.
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Cartron PF, Petit E, Bellot G, Oliver L, Vallette FM. Metaxins 1 and 2, two proteins of the mitochondrial protein sorting and assembly machinery, are essential for Bak activation during TNF alpha triggered apoptosis. Cell Signal 2014; 26:1928-34. [DOI: 10.1016/j.cellsig.2014.04.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 04/27/2014] [Indexed: 10/25/2022]
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Zhang Y, Iqbal S, O'Leary MFN, Menzies KJ, Saleem A, Ding S, Hood DA. Altered mitochondrial morphology and defective protein import reveal novel roles for Bax and/or Bak in skeletal muscle. Am J Physiol Cell Physiol 2013; 305:C502-11. [DOI: 10.1152/ajpcell.00058.2013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The function Bax and/or Bak in constituting a gateway for mitochondrial apoptosis in response to apoptotic stimuli has been unequivocally demonstrated. However, recent work has suggested that Bax/Bak may have unrecognized nonapoptotic functions related to mitochondrial function in nonstressful environments. Wild-type (WT) and Bax/Bak double knockout (DKO) mice were used to determine alternative roles for Bax and Bak in mitochondrial morphology and protein import in skeletal muscle. The absence of Bax and/or Bak altered mitochondrial dynamics by regulating protein components of the organelle fission and fusion machinery. Moreover, DKO mice exhibited defective mitochondrial protein import, both into the matrix and outer membrane compartments, which was consistent with our observations of impaired membrane potential and attenuated expression of protein import machinery (PIM) components in intermyofibrillar mitochondria. Furthermore, the cytosolic chaperones heat-shock protein 90 (Hsp90) and binding immunoglobulin protein (BiP) were markedly increased with the deletion of Bax/Bak, indicating that the cytosolic environment related to protein folding may be changed in DKO mice. Interestingly, endurance training fully restored the deficiency of protein import in DKO mice, likely via the upregulation of PIM components and through improved cytosolic chaperone protein expression. Thus our results emphasize novel roles for Bax and/or Bak in mitochondrial function and provide evidence, for the first time, of a curative function of exercise training in ameliorating a condition of defective mitochondrial protein import.
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Affiliation(s)
- Yuan Zhang
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
- Muscle Health Research Centre, York University, Toronto, Ontario, Canada
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention, Ministry of Education of China, Shanghai, China; and
- College of Physical Education and Health, East China Normal University, Shanghai, China
| | - Sobia Iqbal
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
- Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Michael F. N. O'Leary
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
- Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Keir J. Menzies
- Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Ayesha Saleem
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
- Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Shuzhe Ding
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention, Ministry of Education of China, Shanghai, China; and
- College of Physical Education and Health, East China Normal University, Shanghai, China
| | - David A. Hood
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
- Muscle Health Research Centre, York University, Toronto, Ontario, Canada
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Feng L, Zhang D, Fan C, Ma C, Yang W, Meng Y, Wu W, Guan S, Jiang B, Yang M, Liu X, Guo D. ER stress-mediated apoptosis induced by celastrol in cancer cells and important role of glycogen synthase kinase-3β in the signal network. Cell Death Dis 2013; 4:e715. [PMID: 23846217 PMCID: PMC3730400 DOI: 10.1038/cddis.2013.222] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 01/13/2023]
Abstract
HeLa cells treated with celastrol, a natural compound with inhibitive effect on proteasome, exhibited increase in apoptotic rate and characteristics of apoptosis. To clarify the signal network activated by celastrol to induce apoptosis, both the direct target proteins and undirect target proteins of celastrol were searched in the present study. Proteasome catalytic subunit β1 was predicted by computational analysis to be a possible direct target of celastrol and confirmed by checking direct effect of celastrol on the activity of recombinant human proteasome subunit β1 in vitro. Undirect target-related proteins of celastrol were searched using proteomic studies including two-dimensional electrophoresis (2-DE) analysis and iTRAQ-based LC-MS analysis. Possible target-related proteins of celastrol such as endoplasmic reticulum protein 29 (ERP29) and mitochondrial import receptor Tom22 (TOM22) were found by 2-DE analysis of total cellular protein expression profiles. Further study showed that celastrol induced ER stress and ER stress inhibitor could ameliorate cell death induced by celastrol. Celastrol induced translocation of Bax into the mitochondria, which might be related to the upregulation of BH-3-only proteins such as BIM and the increase in the expression level of TOM22. To further search possible target-related proteins of celastrol in ER and ER-related fractions, iTRAQ-based LC-MS method was use to analyze protein expression profiles of ER/microsomal vesicles-riched fraction of cells with or without celastrol treatment. Based on possible target-related proteins found in both 2-DE analysis and iTRAQ-based LC-MS analysis, protein–protein interaction (PPI) network was established using bioinformatic analysis. The important role of glycogen synthase kinase-3β (GSK3β) in the signal cascades of celastrol was suggested. Pretreatment of LiCL, an inhibitor of GSK3β, could significantly ameliorate apoptosis induced by celastrol. On the basis of the results of the present study, possible signal network of celastrol activated by celastrol leading to apoptosis was predicted.
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Affiliation(s)
- L Feng
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, PR China
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Renault TT, Chipuk JE. Inter-organellar communication with mitochondria regulates both the intrinsic and extrinsic pathways of apoptosis. Commun Integr Biol 2013; 6:e22872. [PMID: 23750296 PMCID: PMC3609836 DOI: 10.4161/cib.22872] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 11/13/2012] [Indexed: 01/11/2023] Open
Abstract
One of our major research interests is to define BCL-2 family function in the cellular decision to induce mitochondrial outer membrane permeabilization and apoptosis. Curiosity in BCL-2 family - mitochondrial interactions led to the identification that the sphingolipid pathway plays a crucial role in BCL-2 family function. For approximately 20 years, sphingolipid biology and apoptotic mechanisms have criss-crossed, but remained distinct, as neither literature could explain the observable interplay between these pathways. We recently identified that two products within the sphingolipid pathway, sphingosine-1-PO4 and hexadecenal, directly regulate BAK and BAX activation, respectively. Furthermore, our work suggests that mitochondrial communication with heterotypic membrane and/or organelles may be an important regulatory mechanism for apoptotic sensitivity.
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Affiliation(s)
- Thibaud T Renault
- Department of Oncological Sciences; Mount Sinai School of Medicine; New York, NY USA ; The Tisch Cancer Institute; New York, NY USA
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Cytochrome c produces pores in cardiolipin-containing planar bilayer lipid membranes in the presence of hydrogen peroxide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:208-12. [PMID: 23085196 DOI: 10.1016/j.bbamem.2012.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 09/21/2012] [Accepted: 10/03/2012] [Indexed: 11/20/2022]
Abstract
Interaction of cytochrome c with cardiolipin in the presence of hydrogen peroxide induces peroxidase activity in cytochrome c and the ability to oxidize membrane lipids. These cytochrome c properties play a substantial role in the cytochrome c-mediated apoptotic reactions. In the present study the electric properties (specific capacitance and integral conductance) of the cardiolipin-containing asolectin planar bilayer lipid membranes (pBLM) in the presence of cytochrome c and hydrogen peroxide were studied. Cytochrome c interaction with cardiolipin-containing pBLM in the presence of hydrogen peroxide resulted in the dramatic increase of the conductance, pore production, their growth up to 3.5 nm diameter and subsequent membrane destruction. In the absence of hydrogen peroxide cytochrome c demonstrated almost no effect on the membrane capacitance and conductance. The data obtained prove the pivotal role of cytochrome c and membrane lipids in the permeabilization of pBLM. Correlation of apoptotic reactions and cytochrome c-mediated membrane permeability is discussed.
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Bax activation initiates the assembly of a multimeric catalyst that facilitates Bax pore formation in mitochondrial outer membranes. PLoS Biol 2012; 10:e1001394. [PMID: 23049480 PMCID: PMC3457932 DOI: 10.1371/journal.pbio.1001394] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 08/15/2012] [Indexed: 11/19/2022] Open
Abstract
Bax/Bak-mediated mitochondrial outer membrane permeabilization (MOMP) is essential for "intrinsic" apoptotic cell death. Published studies used synthetic liposomes to reveal an intrinsic pore-forming activity of Bax, but it is unclear how other mitochondrial outer membrane (MOM) proteins might facilitate this function. We carefully analyzed the kinetics of Bax-mediated pore formation in isolated MOMs, with some unexpected results. Native MOMs were more sensitive than liposomes to added Bax, and MOMs displayed a lag phase not observed with liposomes. Heat-labile MOM proteins were required for this enhanced response. A two-tiered mathematical model closely fit the kinetic data: first, Bax activation promotes the assembly of a multimeric complex, which then catalyzes the second reaction, Bax-dependent pore formation. Bax insertion occurred immediately upon Bax addition, prior to the end of the lag phase. Permeabilization kinetics were affected in a reciprocal manner by [cBid] and [Bax], confirming the "hit-and-run" hypothesis of cBid-induced direct Bax activation. Surprisingly, MOMP rate constants were linearly related to [Bax], implying that Bax acts non-cooperatively. Thus, the oligomeric catalyst is distinct from Bax. Moreover, contrary to common assumption, pore formation kinetics depend on Bax monomers, not oligomers. Catalyst formation exhibited a sharp transition in activation energy at ∼28°C, suggesting a role for membrane lipid packing. Furthermore, catalyst formation was strongly inhibited by chemical antagonists of the yeast mitochondrial fission protein, Dnm1. However, the mammalian ortholog, Drp1, was undetectable in mitochondrial outer membranes. Moreover, ATP and GTP were dispensable for MOMP. Thus, the data argue that oligomerization of a catalyst protein, distinct from Bax and Drp1, facilitates MOMP, possibly through a membrane-remodeling event.
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29
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Vogel S, Raulf N, Bregenhorn S, Biniossek ML, Maurer U, Czabotar P, Borner C. Cytosolic Bax: does it require binding proteins to keep its pro-apoptotic activity in check? J Biol Chem 2012; 287:9112-27. [PMID: 22277657 DOI: 10.1074/jbc.m111.248906] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bax is kept inactive in the cytosol by refolding its C-terminal transmembrane domain into the hydrophobic binding pocket. Although energetic calculations predicted this conformation to be stable, numerous Bax binding proteins were reported and suggested to further stabilize inactive Bax. Unfortunately, most of them have not been validated in a physiological context on the endogenous level. Here we use gel filtration analysis of the cytosol of primary and established cells to show that endogenous, inactive Bax runs 20-30 kDa higher than recombinant Bax, suggesting Bax dimerization or the binding of a small protein. Dimerization was excluded by a lack of interaction of differentially tagged Bax proteins and by comparing the sizes of dimerized recombinant Bax with cytosolic Bax on blue native gels. Surprisingly, when analyzing cytosolic Bax complexes by high sensitivity mass spectrometry after anti-Bax immunoprecipitation or consecutive purification by gel filtration and blue native gel electrophoresis, we detected only one protein, called p23 hsp90 co-chaperone, which consistently and specifically co-purified with Bax. However, this protein could not be validated as a crucial inhibitory Bax binding partner as its over- or underexpression did not show any apoptosis defects. By contrast, cytosolic Bax exhibits a slight molecular mass shift on SDS-PAGE as compared with recombinant Bax, which suggests a posttranslational modification and/or a structural difference between the two proteins. We propose that in most healthy cells, cytosolic endogenous Bax is a monomeric protein that does not necessarily need a binding partner to keep its pro-apoptotic activity in check.
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Affiliation(s)
- Sandra Vogel
- Institute of Molecular Medicine and Cell Research, Center for Biochemistry and Molecular Cell Research, Albert Ludwigs University, Freiburg, Germany
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Abstract
Apoptosis is a process of programmed cell death that serves as a major mechanism for the precise regulation of cell numbers, and as a defense mechanism to remove unwanted and potentially dangerous cells. Studies in nematode, Drosophila and mammals have shown that, although regulation of the cell death machinery is somehow different from one species to another, it is controlled by homologous proteins and involves mitochondria. In mammals, activation of caspases (cysteine proteases that are the main executioners of apoptosis) is under the tight control of the Bcl-2 family proteins, named in reference to the first discovered mammalian cell death regulator. These proteins mainly act by regulating the release of caspases activators from mitochondria. Although for a long time the absence of mitochondrial changes was considered as a hallmark of apoptosis, mitochondria appear today as the central executioner of apoptosis. In this chapter, we present the current view on the mitochondrial pathway of apoptosis with a particular attention to new aspects of the regulation of the Bcl-2 proteins family control of mitochondrial membrane permeabilization: the mechanisms implicated in their mitochondrial targeting and activation during apoptosis, the function(s) of the oncosuppressive protein p53 at the mitochondria and the role of the processes of mitochondrial fusion and fission.
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31
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Renault TT, Grandier-Vazeille X, Arokium H, Velours G, Camougrand N, Priault M, Teijido O, Dejean LM, Manon S. The cytosolic domain of human Tom22 modulates human Bax mitochondrial translocation and conformation in yeast. FEBS Lett 2011; 586:116-21. [DOI: 10.1016/j.febslet.2011.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/15/2011] [Accepted: 12/01/2011] [Indexed: 10/14/2022]
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Becker T, Wenz LS, Krüger V, Lehmann W, Müller JM, Goroncy L, Zufall N, Lithgow T, Guiard B, Chacinska A, Wagner R, Meisinger C, Pfanner N. The mitochondrial import protein Mim1 promotes biogenesis of multispanning outer membrane proteins. ACTA ACUST UNITED AC 2011; 194:387-95. [PMID: 21825073 PMCID: PMC3153637 DOI: 10.1083/jcb.201102044] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Mim1 complex imports α-helical mitochondrial outer membrane proteins with multiple transmembrane segments. The mitochondrial outer membrane contains translocase complexes for the import of precursor proteins. The translocase of the outer membrane complex functions as a general preprotein entry gate, whereas the sorting and assembly machinery complex mediates membrane insertion of β-barrel proteins of the outer membrane. Several α-helical outer membrane proteins are known to carry multiple transmembrane segments; however, only limited information is available on the biogenesis of these proteins. We report that mitochondria lacking the mitochondrial import protein 1 (Mim1) are impaired in the biogenesis of multispanning outer membrane proteins, whereas overexpression of Mim1 stimulates their import. The Mim1 complex cooperates with the receptor Tom70 in binding of precursor proteins and promotes their insertion and assembly into the outer membrane. We conclude that the Mim1 complex plays a central role in the import of α-helical outer membrane proteins with multiple transmembrane segments.
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Affiliation(s)
- Thomas Becker
- Institute for Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research, Freiburg, Germany
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33
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Abstract
The pro-apoptototic protein Bax (Bcl-2 Associated protein X) plays a central role in the mitochondria-dependent apoptotic pathway. In healthy mammalian cells, Bax is essentially cytosolic and inactive. Following a death signal, the protein is translocated to the outer mitochondrial membrane, where it promotes a permeabilization that favors the release of different apoptogenic factors, such as cytochrome c. The regulation of Bax translocation is associated to conformational changes that are under the control of different factors. The evidences showing the involvement of different Bax domains in its mitochondrial localization are presented. The interactions between Bax and its different partners are described in relation to their ability to promote (or prevent) Bax conformational changes leading to mitochondrial addressing and to the acquisition of the capacity to permeabilize the outer mitochondrial membrane.
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Affiliation(s)
- Thibaud T Renault
- CNRS, Institut de Biochimie et de Génétique Cellulaires, UMR5095, F-33000 Bordeaux, France
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34
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Hossain MS, Johannisson A, Wallgren M, Nagy S, Siqueira AP, Rodriguez-Martinez H. Flow cytometry for the assessment of animal sperm integrity and functionality: state of the art. Asian J Androl 2011; 13:406-19. [PMID: 21478895 PMCID: PMC3739346 DOI: 10.1038/aja.2011.15] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 11/19/2010] [Accepted: 01/26/2011] [Indexed: 11/09/2022] Open
Abstract
Flow cytometry is now a recognized methodology within animal spermatology, and has moved from being a research tool to become routine in the assessment of animal semen destined to breeding. The availability of 'bench-top' flow cytometers and of newer and versatile markers for cell structure and function had allowed the instrumentation to measure more sperm parameters, from viability to reactiveness when exposed to exogenous stimuli, and to increase our capabilities to sort spermatozoa for potential fertilizing capacity, or chromosomal sex. The present review summarizes the state of the art regarding flow cytometry applied to animal andrology, albeit keeping an open comparative intent. It critically evaluates the present and future capabilities of flow cytometry for the diagnostics of potential fertility and for the development of current reproductive technologies such as sperm freezing, sperm selection and sperm sorting. The flow cytometry methods will probably further revolutionize our understanding of the sperm physiology and their functionality, and will undoubtedly extend its application in isolating many uncharacterized features of spermatozoa. However, continuous follow-up of the methods is a necessity owing to technical developments and the complexity of mapping spermatozoa.
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Affiliation(s)
- Md Sharoare Hossain
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences (SLU), SE-750 07 Uppsala, Sweden
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35
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Dukanovic J, Rapaport D. Multiple pathways in the integration of proteins into the mitochondrial outer membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:971-80. [DOI: 10.1016/j.bbamem.2010.06.021] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 06/22/2010] [Accepted: 06/23/2010] [Indexed: 11/25/2022]
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36
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Lindsay J, Esposti MD, Gilmore AP. Bcl-2 proteins and mitochondria--specificity in membrane targeting for death. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:532-9. [PMID: 21056595 DOI: 10.1016/j.bbamcr.2010.10.017] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 10/22/2010] [Accepted: 10/27/2010] [Indexed: 01/10/2023]
Abstract
The localization and control of Bcl-2 proteins on mitochondria is essential for the intrinsic pathway of apoptosis. Anti-apoptotic Bcl-2 proteins reside on the outer mitochondrial membrane (OMM) and prevent apoptosis by inhibiting the activation of the pro-apoptotic family members Bax and Bak. The Bcl-2 subfamily of BH3-only proteins can either inhibit the anti-apoptotic proteins or directly activate Bax or Bak. How these proteins interact with each other, the mitochondrial surface and within the OMM are complex processes we are only beginning to understand. However, these interactions are fundamental for the transduction of apoptotic signals to mitochondria and the subsequent release of caspase activating factors into the cytosol. In this review we will discuss our knowledge of how Bcl-2 proteins are directed to mitochondria in the first place, a crucial but poorly understood aspect of their regulation. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
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Affiliation(s)
- Jennefer Lindsay
- Wellcome Trust Centre for Cell Matrix Research, Faculty of Life Sciences The University of Manchester, UK.
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37
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Montessuit S, Somasekharan SP, Terrones O, Lucken-Ardjomande S, Herzig S, Schwarzenbacher R, Manstein DJ, Bossy-Wetzel E, Basañez G, Meda P, Martinou JC. Membrane remodeling induced by the dynamin-related protein Drp1 stimulates Bax oligomerization. Cell 2010; 142:889-901. [PMID: 20850011 DOI: 10.1016/j.cell.2010.08.017] [Citation(s) in RCA: 330] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 04/01/2010] [Accepted: 08/10/2010] [Indexed: 01/08/2023]
Abstract
In response to many apoptotic stimuli, oligomerization of Bax is essential for mitochondrial outer membrane permeabilization and the ensuing release of cytochrome c. These events are accompanied by mitochondrial fission that appears to require Drp1, a large GTPase of the dynamin superfamily. Loss of Drp1 leads to decreased cytochrome c release by a mechanism that is poorly understood. Here we show that Drp1 stimulates tBid-induced Bax oligomerization and cytochrome c release by promoting tethering and hemifusion of membranes in vitro. This function of Drp1 is independent of its GTPase activity and relies on arginine 247 and the presence of cardiolipin in membranes. In cells, overexpression of Drp1 R247A/E delays Bax oligomerization and cell death. Our findings uncover a function of Drp1 and provide insight into the mechanism of Bax oligomerization.
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Affiliation(s)
- Sylvie Montessuit
- Department of Cell Biology, University of Geneva, Sciences III, 30 quai Ernest Ansermet, 1211 Geneva 4, Switzerland
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38
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Ilkow CS, Willows SD, Hobman TC. Rubella virus capsid protein: a small protein with big functions. Future Microbiol 2010; 5:571-84. [PMID: 20353299 DOI: 10.2217/fmb.10.27] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Virus replication occurs in the midst of a life or death struggle between the virus and the infected host cell. To limit virus replication, host cells can activate a number of antiviral pathways, the most drastic of which is programmed cell death. Whereas large DNA viruses have the luxury of encoding accessory proteins whose main function is to interfere with host cell defences, the genomes of RNA viruses are not large enough to encode proteins of this type. Recent studies have revealed that proteins encoded by RNA viruses often play multiple roles in the battles between viruses and host cells. In this article, we discuss the many functions of the rubella virus capsid protein. This protein has well-defined roles in virus assembly, but recent research suggests that it also functions to modulate virus replication and block host cell defences.
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Affiliation(s)
- Carolina S Ilkow
- Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7, Canada.
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39
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Van Herreweghe F, Festjens N, Declercq W, Vandenabeele P. Tumor necrosis factor-mediated cell death: to break or to burst, that's the question. Cell Mol Life Sci 2010; 67:1567-79. [PMID: 20198502 PMCID: PMC11115929 DOI: 10.1007/s00018-010-0283-0] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 01/20/2010] [Indexed: 02/06/2023]
Abstract
In this review, we discuss the signal-transduction pathways of three major cellular responses induced by tumor necrosis factor (TNF): cell survival through NF-kappaB activation, apoptosis, and necrosis. Recruitment and activation of caspases plays a crucial role in the initiation and execution of TNF-induced apoptosis. However, experimental inhibition of caspases reveals an alternative cell death pathway, namely necrosis, also called necroptosis, suggesting that caspases actively suppress the latter outcome. TNF-induced necrotic cell death crucially depends on the kinase activity of receptor interacting protein serine-threonine kinase 1 (RIP1) and RIP3. It was recently demonstrated that ubiquitination of RIP1 determines whether it will function as a pro-survival or pro-cell death molecule. Deeper insight into the mechanisms that control the molecular switches between cell survival and cell death will help us to understand why TNF can exert so many different biological functions in the etiology and pathogenesis of human diseases.
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Affiliation(s)
- Franky Van Herreweghe
- Unit For Molecular Signalling and Cell Death, Department for Molecular Biomedical Research, VIB, Technologiepark 927, 9052 Ghent (Zwijnaarde), Belgium
- Unit for Molecular Signalling and Cell Death, Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, 9052 Ghent, Belgium
| | - Nele Festjens
- Unit for Molecular Glycobiology, Department for Molecular Biomedical Research, VIB, Ghent University, Technologiepark 927, 9052 Ghent, Belgium
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University, Ledeganckstraat 35, 9052 Ghent, Belgium
| | - Wim Declercq
- Unit For Molecular Signalling and Cell Death, Department for Molecular Biomedical Research, VIB, Technologiepark 927, 9052 Ghent (Zwijnaarde), Belgium
- Unit for Molecular Signalling and Cell Death, Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, 9052 Ghent, Belgium
| | - Peter Vandenabeele
- Unit For Molecular Signalling and Cell Death, Department for Molecular Biomedical Research, VIB, Technologiepark 927, 9052 Ghent (Zwijnaarde), Belgium
- Unit for Molecular Signalling and Cell Death, Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, 9052 Ghent, Belgium
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40
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Circu ML, Aw TY. Reactive oxygen species, cellular redox systems, and apoptosis. Free Radic Biol Med 2010; 48:749-62. [PMID: 20045723 PMCID: PMC2823977 DOI: 10.1016/j.freeradbiomed.2009.12.022] [Citation(s) in RCA: 2330] [Impact Index Per Article: 166.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 12/21/2009] [Accepted: 12/27/2009] [Indexed: 02/07/2023]
Abstract
Reactive oxygen species (ROS) are products of normal metabolism and xenobiotic exposure, and depending on their concentration, ROS can be beneficial or harmful to cells and tissues. At physiological low levels, ROS function as "redox messengers" in intracellular signaling and regulation, whereas excess ROS induce oxidative modification of cellular macromolecules, inhibit protein function, and promote cell death. Additionally, various redox systems, such as the glutathione, thioredoxin, and pyridine nucleotide redox couples, participate in cell signaling and modulation of cell function, including apoptotic cell death. Cell apoptosis is initiated by extracellular and intracellular signals via two main pathways, the death receptor- and the mitochondria-mediated pathways. Various pathologies can result from oxidative stress-induced apoptotic signaling that is consequent to ROS increases and/or antioxidant decreases, disruption of intracellular redox homeostasis, and irreversible oxidative modifications of lipid, protein, or DNA. In this review, we focus on several key aspects of ROS and redox mechanisms in apoptotic signaling and highlight the gaps in knowledge and potential avenues for further investigation. A full understanding of the redox control of apoptotic initiation and execution could underpin the development of therapeutic interventions targeted at oxidative stress-associated disorders.
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Affiliation(s)
- Magdalena L Circu
- Department of Molecular & Cellular Physiology, Louisiana University Health Sciences Center, Shreveport, LA 71130, USA
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41
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Adenine nucleotide translocase: a component of the phylogenetically conserved cell death machinery. Cell Death Differ 2009; 16:1419-25. [DOI: 10.1038/cdd.2009.118] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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42
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Abstract
Mitochondrial membrane permeabilization is central to apoptotic signaling and is directly regulated by the Bcl-2 family of proteins, consisting of anti-apoptotic members and pro-apoptotic members, although the precise mechanisms involved remain elusive. When cells are deficient in both pro-apoptotic multidomain members of this family (Bax and Bak), mitochondrial membrane permeabilization does not occur in response to various apoptotic stimuli. We have previously reported that the voltage-dependent anion channel (VDAC or porin) plays a role in apoptotic mitochondrial membrane permeabilization by interacting with Bcl-2 family members. Here, we have provided additional evidence that VDAC2 is required for pro-apoptotic activity of Bax in the absence of Bak. In the absence of Bak, VDAC2-deficient cells showed strong resistance to various apoptotic stimuli, whereas re-introduction of the Vdac2 gene restored their apoptotic response. Consistently, silencing of VDAC2 in Bak-deficient cells, but not Bax-deficient cells, also conferred resistance to various apoptotic stimuli. In the absence of VDAC2 and Bak, the activation of Bax (assessed by mitochondrial membrane integration, conformational changes and oligomerization) was markedly impaired. Taken together, these findings indicate that VDAC2 is required for pro-apoptotic activity of Bax in the absence of Bak.
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43
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Abstract
The release of pro-apoptotic proteins from the mitochondria is a key event in cell death signaling that is regulated by Bcl-2 family proteins. For example, cleavage of the BH3-only protein, Bid, by multiple proteases leads to the formation of truncated Bid that, in turn, promotes the insertion/oligomerization of Bax into the mitochondrial outer membrane, resulting in pore formation and the release of proteins residing in the intermembrane space. Bax, a monomeric protein in the cytosol is targeted to the mitochondria by a yet unknown mechanism. Several proteins of the outer mitochondrial membrane have been proposed to act as receptors for Bax, among them the voltage-dependent anion channel, VDAC, and the mitochondrial protein translocase of the outer membrane, the TOM complex. Alternatively, the unique mitochondrial phospholipid, cardiolipin, has been ascribed a similar function. Here, we review recent work on the mechanisms of activation and the targeting of Bax to the mitochondria and discuss the advantages and limitations of the methods used to study this process.
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44
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Du W, Ayscough KR. Methyl beta-cyclodextrin reduces accumulation of reactive oxygen species and cell death in yeast. Free Radic Biol Med 2009; 46:1478-87. [PMID: 19272445 DOI: 10.1016/j.freeradbiomed.2009.02.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 02/20/2009] [Accepted: 02/23/2009] [Indexed: 01/10/2023]
Abstract
Stabilized F-actin structures have been shown to be detrimental to both mammalian and yeast cells. In yeast, stabilization of actin caused by addition of jasplakinolide, by point mutations in the act1 gene, or by deletion of certain genes that regulate F-actin leads to cell death with hallmarks of apoptosis. In particular, there is an elevation in the levels of reactive oxygen species, and we have shown the importance of the Ras/cAMP pathway for this effect. Here we show that in yeast cells deleted for end3, which functions to regulate actin organization during endocytosis, treatment of cells with methyl beta-cyclodextrin reduces levels of reactive oxygen species and inhibits cell death progression. Methyl beta-cyclodextrin is widely used to disrupt lipid rafts that contain cholesterol. The mechanism through which the rescue is achieved was investigated and we demonstrate that methyl beta-cyclodextrin reduces accumulation of Ras2 at the plasma membrane in Deltaend3 cells. We use FRAP and live cell imaging to determine the possible mechanism through which methyl beta-cyclodextrin functions to elicit this effect on Ras2 localization. Finally, we demonstrate that addition of methyl beta-cyclodextrin to wild-type cells can act to protect cells from acute oxidative stress caused by addition of hydrogen peroxide.
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Affiliation(s)
- Wei Du
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
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Veresov VG, Davidovskii AI. Activation of Bax by joint action of tBid and mitochondrial outer membrane: Monte Carlo simulations. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 38:941-60. [PMID: 19466402 DOI: 10.1007/s00249-009-0475-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Revised: 04/30/2009] [Accepted: 05/04/2009] [Indexed: 12/31/2022]
Abstract
The mitochondrial pathway of apoptosis proceeds when molecules, such as cytochrome c, sequestered between the outer and inner mitochondrial membranes are released to the cytosol by mitochondrial outer membrane (MOM) permeabilization. Bax, a member of the Bcl-2 protein family, plays a pivotal role in mitochondrion-mediated apoptosis. In response to apoptotic stimuli, Bax integrates into the MOM, where it mediates the release of cytochrome c from the intermembrane space into the cytosol, leading to caspase activation and cell death. The pro-death action of Bax is regulated by interactions with both other prosurvival proteins, such as tBid, and the MOM, but the exact mechanisms remain largely unclear. Here, the mechanisms of integration of Bax into a model membrane mimicking the MOM were studied by Monte Carlo simulations preceded by a computer prediction of the docking of tBid with Bax. A novel model of Bax activation by tBid was predicted by the simulations. In this model, tBid binds to Bax at an interaction site formed by Bax helices alpha1, alpha2, alpha3 and alpha5 leading, due to interaction of the positively charged N-terminal fragment of tBid with anionic lipid headgroups, to Bax reorientation such that a hydrogen-bonded pair of residues, Asp98 and Ser184, is brought into close proximity with negatively charged lipid headgroups. The interaction with these headgroups destabilizes the hydrogen bond which results in the release of helix alpha9 from the Bax-binding groove, its insertion into the membrane, followed by insertion into the membrane of the alpha5-alpha6 helical hairpin.
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Affiliation(s)
- Valery G Veresov
- Department of Cell Biophysics, Institute of Biophysics and Cell Engineering, Academicheskaya St. 27, Minsk, 220072, Belarus.
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Colin J, Garibal J, Mignotte B, Guénal I. The mitochondrial TOM complex modulates bax-induced apoptosis in Drosophila. Biochem Biophys Res Commun 2009; 379:939-43. [DOI: 10.1016/j.bbrc.2008.12.176] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 12/28/2008] [Indexed: 10/21/2022]
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TOM-independent complex formation of Bax and Bak in mammalian mitochondria during TNFα-induced apoptosis. Cell Death Differ 2009; 16:697-707. [DOI: 10.1038/cdd.2008.194] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Sapienza K, Bannister W, Balzan R. Mitochondrial involvement in aspirin-induced apoptosis in yeast. MICROBIOLOGY-SGM 2008; 154:2740-2747. [PMID: 18757807 DOI: 10.1099/mic.0.2008/017228-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We have previously reported that aspirin induces apoptosis in manganese superoxide dismutase (MnSOD)-deficient Saccharomyces cerevisiae cells when cultivated on the non-fermentable carbon source ethanol. Here, we investigated the role of mitochondria in aspirin-induced apoptosis. We report that aspirin had an inhibitory effect on cellular respiration, and caused the release of most of the mitochondrial cytochrome c and a dramatic drop in the mitochondrial membrane potential (DeltaPsi(m)). Also, aspirin reduced the intracellular cytosolic pH in the MnSOD-deficient cells growing in ethanol medium, but this did not seem to be the initial trigger that committed these cells to aspirin-induced apoptosis. Furthermore, loss of DeltaPsi(m) was not required for aspirin-induced release of cytochrome c, since the initial release of cytochrome c occurred prior to the disruption of the DeltaPsi(m). It is thus possible that cytochrome c release does not involve the early onset of the mitochondrial permeability transition, but only an alteration of the permeability of the outer mitochondrial membrane.
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Affiliation(s)
- Karen Sapienza
- Department of Physiology and Biochemistry, University of Malta, Msida MSD 2080, Malta
| | - William Bannister
- Department of Physiology and Biochemistry, University of Malta, Msida MSD 2080, Malta
| | - Rena Balzan
- Department of Physiology and Biochemistry, University of Malta, Msida MSD 2080, Malta
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Cartron PF, Bellot G, Oliver L, Grandier-Vazeille X, Manon S, Vallette FM. Bax inserts into the mitochondrial outer membrane by different mechanisms. FEBS Lett 2008; 582:3045-51. [DOI: 10.1016/j.febslet.2008.07.047] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 07/14/2008] [Accepted: 07/18/2008] [Indexed: 11/25/2022]
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Abstract
Apoptosis or programmed cell death represents a physiologically conserved mechanism of cell death that is pivotal in normal development and tissue homeostasis in all organisms. As a key modulator of cell functions, the most abundant non-protein thiol, glutathione (GSH), has important roles in cellular defense against oxidant aggression, redox regulation of proteins thiols and maintaining redox homeostasis that is critical for proper function of cellular processes, including apoptosis. Thus, a shift in the cellular GSH-to-GSSG redox balance in favour of the oxidized species, GSSG, constitutes an important signal that could decide the fate of a cell. The current review will focus on three main areas: (1) general description of cellular apoptotic pathways, (2) cellular compartmentation of GSH and the contribution of mitochondrial GSH and redox proteins to apoptotic signalling and (3) role of redox mechanisms in the initiation and execution phases of apoptosis.
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Affiliation(s)
- Magdalena L Circu
- Department of Molecular & Cellular Physiology, Louisiana University Health Sciences Center, Shreveport, Louisiana, USA
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