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Czabotar PE, Garcia-Saez AJ. Mechanisms of BCL-2 family proteins in mitochondrial apoptosis. Nat Rev Mol Cell Biol 2023; 24:732-748. [PMID: 37438560 DOI: 10.1038/s41580-023-00629-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2023] [Indexed: 07/14/2023]
Abstract
The proteins of the BCL-2 family are key regulators of mitochondrial apoptosis, acting as either promoters or inhibitors of cell death. The functional interplay and balance between the opposing BCL-2 family members control permeabilization of the outer mitochondrial membrane, leading to the release of activators of the caspase cascade into the cytosol and ultimately resulting in cell death. Despite considerable research, our knowledge about the mechanisms of the BCL-2 family of proteins remains insufficient, which complicates cell fate predictions and does not allow us to fully exploit these proteins as targets for drug discovery. Detailed understanding of the formation and molecular architecture of the apoptotic pore in the outer mitochondrial membrane remains a holy grail in the field, but new studies allow us to begin constructing a structural model of its arrangement. Recent literature has also revealed unexpected activities for several BCL-2 family members that challenge established concepts of how they regulate mitochondrial permeabilization. In this Review, we revisit the most important advances in the field and integrate them into a new structure-function-based classification of the BCL-2 family members that intends to provide a comprehensive model for BCL-2 action in apoptosis. We close this Review by discussing the potential of drugging the BCL-2 family in diseases characterized by aberrant apoptosis.
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Affiliation(s)
- Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia.
| | - Ana J Garcia-Saez
- Membrane Biophysics, Institute of Genetics, CECAD, University of Cologne, Cologne, Germany.
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2
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Apoptosis, Pyroptosis, and Necroptosis-Oh My! The Many Ways a Cell Can Die. J Mol Biol 2021; 434:167378. [PMID: 34838807 DOI: 10.1016/j.jmb.2021.167378] [Citation(s) in RCA: 107] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/12/2021] [Accepted: 11/21/2021] [Indexed: 12/12/2022]
Abstract
Cell death is an essential process in all living organisms and occurs through different mechanisms. The three main types of programmed cell death are apoptosis, pyroptosis, and necroptosis, and each of these pathways employs complex molecular and cellular mechanisms. Although there are mechanisms and outcomes specific to each pathway, they share common components and features. In this review, we discuss recent discoveries in these three best understood modes of cell death, highlighting their singularities, and examining the intriguing notion that common players shape different individual pathways in this highly interconnected and coordinated cell death system. Understanding the similarities and differences of these cell death processes is crucial to enable targeted strategies to manipulate these pathways for therapeutic benefit.
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3
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Lemos FO, Bultynck G, Parys JB. A comprehensive overview of the complex world of the endo- and sarcoplasmic reticulum Ca 2+-leak channels. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119020. [PMID: 33798602 DOI: 10.1016/j.bbamcr.2021.119020] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/09/2021] [Accepted: 03/13/2021] [Indexed: 12/11/2022]
Abstract
Inside cells, the endoplasmic reticulum (ER) forms the largest Ca2+ store. Ca2+ is actively pumped by the SERCA pumps in the ER, where intraluminal Ca2+-binding proteins enable the accumulation of large amount of Ca2+. IP3 receptors and the ryanodine receptors mediate the release of Ca2+ in a controlled way, thereby evoking complex spatio-temporal signals in the cell. The steady state Ca2+ concentration in the ER of about 500 μM results from the balance between SERCA-mediated Ca2+ uptake and the passive leakage of Ca2+. The passive Ca2+ leak from the ER is often ignored, but can play an important physiological role, depending on the cellular context. Moreover, excessive Ca2+ leakage significantly lowers the amount of Ca2+ stored in the ER compared to normal conditions, thereby limiting the possibility to evoke Ca2+ signals and/or causing ER stress, leading to pathological consequences. The so-called Ca2+-leak channels responsible for Ca2+ leakage from the ER are however still not well understood, despite over 20 different proteins have been proposed to contribute to it. This review has the aim to critically evaluate the available evidence about the various channels potentially involved and to draw conclusions about their relative importance.
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Affiliation(s)
- Fernanda O Lemos
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, B-3000 Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, B-3000 Leuven, Belgium
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, B-3000 Leuven, Belgium.
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4
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Flores‐Romero H, Ros U, Garcia‐Saez AJ. Pore formation in regulated cell death. EMBO J 2020; 39:e105753. [PMID: 33124082 PMCID: PMC7705454 DOI: 10.15252/embj.2020105753] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/13/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022] Open
Abstract
The discovery of alternative signaling pathways that regulate cell death has revealed multiple strategies for promoting cell death with diverse consequences at the tissue and organism level. Despite the divergence in the molecular components involved, membrane permeabilization is a common theme in the execution of regulated cell death. In apoptosis, the permeabilization of the outer mitochondrial membrane by BAX and BAK releases apoptotic factors that initiate the caspase cascade and is considered the point of no return in cell death commitment. Pyroptosis and necroptosis also require the perforation of the plasma membrane at the execution step, which involves Gasdermins in pyroptosis, and MLKL in the case of necroptosis. Although BAX/BAK, Gasdermins and MLKL share certain molecular features like oligomerization, they form pores in different cellular membranes via distinct mechanisms. Here, we compare and contrast how BAX/BAK, Gasdermins, and MLKL alter membrane permeability from a structural and biophysical perspective and discuss the general principles of membrane permeabilization in the execution of regulated cell death.
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Affiliation(s)
- Hector Flores‐Romero
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Uris Ros
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Ana J Garcia‐Saez
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
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5
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TAK1 is involved in sodium L-lactate-stimulated p38 signaling and promotes apoptosis. Mol Cell Biochem 2020; 476:873-882. [PMID: 33111211 DOI: 10.1007/s11010-020-03952-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 10/15/2020] [Indexed: 12/31/2022]
Abstract
In the present study, we found that the phosphorylation of p38 mitogen-activated protein kinase (p38) was significantly increased in L-lactate-treated HeLa cells, which is under concentration- and time-dependent manner. The protein level of Bcl-2 was significantly reduced and Bax and C-caspase3 were significantly increased in L-lactate-treated cells. qRT-PCR analysis suggested that the expression level of apoptosis-related genes Bax, C-myc, and FasL were significantly upregulated by L-lactate treatment. In addition, p38 inhibitor SB203580 blocked the L-lactate-stimulated phosphorylation of p38 (p-p38) and apoptosis, which suggested that L-lactate-stimulated apoptosis may be related to the activation of p38. Moreover, TAK1 inhibitor Takinib reduced L-lactate-triggered phosphorylation of p38 and also apoptosis; however, ASK1 inhibitor NQDI-1 did not. Cells transfected with siRNA of TAK1(siTAK1) showed similar results with Takinib inhibitor. These results suggested that the L-lactate treatment elevated activation of p38 and apoptosis was related to TAK1. In this study, we suggested that TAK1 plays an important role in L-lactate-stimulated activation of p38 affecting apoptosis in HeLa cells.
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Edwards G, Lee Y, Kim M, Bhanvadia S, Kim KY, Ju WK. Effect of Ubiquinol on Glaucomatous Neurodegeneration and Oxidative Stress: Studies for Retinal Ganglion Cell Survival and/or Visual Function. Antioxidants (Basel) 2020; 9:E952. [PMID: 33023026 PMCID: PMC7599950 DOI: 10.3390/antiox9100952] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 09/28/2020] [Accepted: 09/29/2020] [Indexed: 01/02/2023] Open
Abstract
Oxidative stress is one of major causal factors in glaucomatous neurodegeneration. Ubiquinol promotes retinal ganglion cell (RGC) survival against glaucomatous insults such as oxidative stress. Here we investigated the effect of ubiquinol on RGC survival and/or visual function in mouse models of glaucoma and oxidative stress. DBA/2J and age-matched DBA/2J-Gpnmb+ (D2-Gpnmb+), which do not develop intraocular pressure elevation, or C57BL/6J mice were fed with ubiquinol (1%) or control diet daily for 5 or 2 months. We assessed RGC survival by Brn3a immunohistochemistry and measured expression levels of active and total BAX, peroxisome proliferator-activated receptor-gamma coactivator 1α, transcription factor A (TFAM) and oxidative phosphorylation (OXPHOS) complex protein. Following induction of oxidative stress by paraquat injection, we also assessed visual function. In glaucomatous retina, ubiquinol supplementation significantly promoted RGC survival, blocked BAX activation and increased TFAM and OXPHOS complex II protein expression. Also, ubiquinol supplementation ameliorated oxidative stress-induced visual dysfunction. These findings indicate that ubiquinol promotes RGC survival by increasing TFAM expression and OXPHOS complex II activity in glaucomatous neurodegeneration, and that ubiquinol enhances RGC survival and preserves visual function against oxidative stress. We propose that ubiquinol has a therapeutic potential for treating oxidative stress-associated glaucomatous neurodegeneration.
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Affiliation(s)
- Genea Edwards
- Hamilton Glaucoma Center and Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92039, USA; (G.E.); (Y.L.); (M.K.); (S.B.)
| | - Yonghoon Lee
- Hamilton Glaucoma Center and Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92039, USA; (G.E.); (Y.L.); (M.K.); (S.B.)
| | - Martha Kim
- Hamilton Glaucoma Center and Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92039, USA; (G.E.); (Y.L.); (M.K.); (S.B.)
- Department of Ophthalmology, Dongguk University Ilsan Hospital, Ilsandong-gu, Goyang-si 10326, Korea
| | - Soham Bhanvadia
- Hamilton Glaucoma Center and Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92039, USA; (G.E.); (Y.L.); (M.K.); (S.B.)
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA 92039, USA;
| | - Won-Kyu Ju
- Hamilton Glaucoma Center and Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92039, USA; (G.E.); (Y.L.); (M.K.); (S.B.)
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7
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Ekicier Acar S, Sarıcaoğlu MS, Çolak A, Aktaş Z, Sepici Dinçel A. Neuroprotective effects of topical coenzyme Q10 + vitamin E in mechanic optic nerve injury model. Eur J Ophthalmol 2019; 30:714-722. [PMID: 30852912 DOI: 10.1177/1120672119833271] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE We aimed to create mechanic optic nerve injury model in rats and investigate the neuroprotective effects of topical Coenzyme Q10 + Vitamin E (CoQ + Vit.E) molecules on retinal ganglion cells. METHODS Mechanic optic nerve injury model was created in the right eyes of rats (n = 12). Rats were divided into two groups: glaucoma model with sham treatment and topical CoQ + Vit.E treatment. Treatment was applied for 4 weeks. Glial fibrillary acidic protein, Brn-3a antibody, and anti-Iba1 were examined by immunohistochemistry. Glial fibrillary acidic protein, Bax, Bcl-xL, and Tfam protein expression were measured by Western blot analysis. RESULTS The number of Brn-3a-positive retinal ganglion cell was 15.0 ± 1.0 (min: 14, max: 16) in sham treatment group and 22.2 ± 4.8 (min: 18, max: 29) in topical CoQ10 + Vit.E treatment group. The protection of Brn-3a in CoQ10 + Vit.E was statistically significant (p < 0.05). Glial fibrillary acidic protein-positive astroglial counts were recorded as 11.7 ± 2.1 (min: 10, max: 14) in sham treatment and 2.5 ± 1.5 (min: 1, max: 4) in topical CoQ10 + Vit.E treatment group (p < 0.05). Topical CoQ10 + Vit.E treatment also decreased Iba1 expression in the retina of mechanic optic nerve injury groups. CoQ10 + Vit.E treatment prevented apoptotic cell death by increasing Bcl-xL protein expression. Also, CoQ10 + Vit.E preserved Tfam protein expression in the retina. CONCLUSION This study has shown that in glaucoma treatment the neuron protecting effect of topical CoQ10 + Vit.E molecules can be valuable.
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Affiliation(s)
| | - M Sinan Sarıcaoğlu
- Eye Clinic, Ankara Numune Training and Research Hospital, Ankara, Turkey
| | - Aysel Çolak
- Pathology Clinic, Ankara Numune Training and Research Hospital, Ankara, Turkey
| | - Zeynep Aktaş
- Department of Ophthalmology, Gazi University Faculty of Medicine, Ankara, Turkey
| | - Aylin Sepici Dinçel
- Department of Biochemistry, Gazi University Faculty of Medicine, Ankara, Turkey
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8
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Ader NR, Hoffmann PC, Ganeva I, Borgeaud AC, Wang C, Youle RJ, Kukulski W. Molecular and topological reorganizations in mitochondrial architecture interplay during Bax-mediated steps of apoptosis. eLife 2019; 8:40712. [PMID: 30714902 PMCID: PMC6361589 DOI: 10.7554/elife.40712] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 01/22/2019] [Indexed: 12/25/2022] Open
Abstract
During apoptosis, Bcl-2 proteins such as Bax and Bak mediate the release of pro-apoptotic proteins from the mitochondria by clustering on the outer mitochondrial membrane and thereby permeabilizing it. However, it remains unclear how outer membrane openings form. Here, we combined different correlative microscopy and electron cryo-tomography approaches to visualize the effects of Bax activity on mitochondria in human cells. Our data show that Bax clusters localize near outer membrane ruptures of highly variable size. Bax clusters contain structural elements suggesting a higher order organization of their components. Furthermore, unfolding of inner membrane cristae is coupled to changes in the supramolecular assembly of ATP synthases, particularly pronounced at membrane segments exposed to the cytosol by ruptures. Based on our results, we propose a comprehensive model in which molecular reorganizations of the inner membrane and sequestration of outer membrane components into Bax clusters interplay in the formation of outer membrane ruptures. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Nicholas R Ader
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Patrick C Hoffmann
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Iva Ganeva
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Alicia C Borgeaud
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Chunxin Wang
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Wanda Kukulski
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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9
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Ju WK, Shim MS, Kim KY, Bu JH, Park TL, Ahn S, Weinreb RN. Ubiquinol promotes retinal ganglion cell survival and blocks the apoptotic pathway in ischemic retinal degeneration. Biochem Biophys Res Commun 2018; 503:2639-2645. [PMID: 30107910 DOI: 10.1016/j.bbrc.2018.08.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 08/02/2018] [Indexed: 02/06/2023]
Abstract
Coenzyme Q10 (CoQ10) protects retinal ganglion cells (RGCs) in experimental retinal ischemia and glaucoma by scavenging reactive oxygen species. We tested whether a diet supplemented with ubiquinol, the reduced form of CoQ10, promotes RGC survival and blocks the apoptotic pathway in ischemic mouse retina induced by acute high intraocular pressure (IOP) elevation. Ubiquinol (1%) treatment significantly promoted RGC survival at 2 weeks after ischemia/reperfusion. The ubiquinol treatment significantly blocked activation of astroglial and microglial cells in the ischemic retina at 2 weeks. While the ubiquinol treatment significantly decreased active Bax protein expression in the ischemic retina, phosphorylation of Bad at serine 112 and Bcl-xL protein expression were preserved in the ubiquinol-treated ischemic retina at 12 h. Consistently, the ubiquinol treatment prevented apoptotic cell death by blocking caspase-3 cleavage. These results suggest that the ubiquinol enhances RGC survival by modulating the Bax/Bad/Bcl-xL-mediated apoptotic pathway in the ischemic retina. Ubiquinol has therapeutic potential for ameliorating elevated IOP-induced ischemic retinal degeneration.
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Affiliation(s)
- Won-Kyu Ju
- Hamilton Glaucoma Center, Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.
| | - Myoung Sup Shim
- Hamilton Glaucoma Center, Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Department of Neuroscience, University of California San Diego, La Jolla, CA, USA
| | - Jung Hyun Bu
- Hamilton Glaucoma Center, Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Tae Lim Park
- Hamilton Glaucoma Center, Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Sangphil Ahn
- Hamilton Glaucoma Center, Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Robert N Weinreb
- Hamilton Glaucoma Center, Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
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10
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Uren RT, Iyer S, Kluck RM. Pore formation by dimeric Bak and Bax: an unusual pore? Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630157 DOI: 10.1098/rstb.2016.0218] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Apoptotic cell death via the mitochondrial pathway occurs in all vertebrate cells and requires the formation of pores in the mitochondrial outer membrane. Two Bcl-2 protein family members, Bak and Bax, form these pores during apoptosis, and how they do so has been investigated for the last two decades. Many of the conformation changes that occur during their transition to pore-forming proteins have now been delineated. Notably, biochemical, biophysical and structural studies indicate that symmetric homodimers are the basic unit of pore formation. Each dimer contains an extended hydrophobic surface that lies on the outer membrane, and is anchored at either end by a transmembrane domain. Membrane-remodelling events such as positive membrane curvature have been reported to accompany apoptotic pore formation, suggesting Bak and Bax form lipidic pores rather than proteinaceous pores. However, it remains unclear how symmetric dimers assemble to porate the membrane. Here, we review how clusters of dimers and their lipid-mediated interactions provide a molecular explanation for the heterogeneous assemblies of Bak and Bax observed during apoptosis.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Rachel T Uren
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Sweta Iyer
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Ruth M Kluck
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia .,Department of Medical Biology, The University of Melbourne, 1G Royal Parade, Parkville, Victoria 3052, Australia
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11
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Baicalein protects against oxLDL-caused oxidative stress and inflammation by modulation of AMPK-alpha. Oncotarget 2018; 7:72458-72468. [PMID: 27776344 PMCID: PMC5341921 DOI: 10.18632/oncotarget.12788] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 10/13/2016] [Indexed: 12/20/2022] Open
Abstract
Atherosclerosis is considered to be a form of chronic inflammation and a disorder of lipid metabolism. Oxidative transformations in the lipid and apolipoprotein B (Apo B) constituent of low density lipoprotein drive the initial step in atherogenesis due to macrophage scavenger receptors identify oxidized LDL (oxLDL) but non-oxidized LDL. The human vascular endothelial cells fact a critical role in vasodilation, provides a nonadhesive surface for circulation, reduces vascular smooth muscle proliferation, inflammation, thrombus formation and platelet aggregation. Assembly of oxLDL contribute to stimulation of endothelial cells with up-regulation of adhesion molecules, increase oxidative stress to the vascular endothelium and inhibition of NO-mediated vasodilation. When adhesion molecules are over-expressed on the surface of endothelial cells under oxLDL stimulation, it will recruit monocytes to the arterial wall. Then adherent monocytes will migrate into the subendothelial space and subsequently differentiate into macrophages. In the subendothelial space, oxLDL will be taken up by macrophages, thereby causing the substantial cholesterol accumulation and the foam cells production.
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12
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Chan SH, Hung CH, Shih JY, Chu PM, Cheng YH, Tsai YJ, Lin HC, Tsai KL. Baicalein is an available anti-atherosclerotic compound through modulation of nitric oxide-related mechanism under oxLDL exposure. Oncotarget 2018; 7:42881-42891. [PMID: 27356749 PMCID: PMC5189994 DOI: 10.18632/oncotarget.10263] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/13/2016] [Indexed: 01/25/2023] Open
Abstract
OxLDL facilitate reactive oxygen species (ROS) formation and up-regulation of the executioner caspase-3 via the mitochondrial apoptotic pathway involves several critical steps in human endothelial cells. Previous studies reported that oxLDL-facilitated endothelial oxidative stress is associated with impairment of eNOS and up-regulation of inducible nitric oxide synthase (iNOS). Baicalein is the most abundant component that has anti-HIV, anti-tumor, anti-oxidant and free radical scavenging functions. In this present study, we shown that baicalein hinibits oxLDL-caused endothelial dysfunction through suppression of endothelial inflammation and oxidative stress that causes to cellular apoptosis. Specifically, baicalein reduces the elevation of ROS concentration, which subsequently inhibits the oxLDL-decreased expression of anti-oxidant enzymes, enriches the bioavailability of NO, stabilizes the mitochondrial membrane, thereby inhibiting the discharge of cytochrome c from mitochondria, a molecule required for the activation of the pro-apoptotic protein caspase 3. However, inhibition of eNOS impairs the anti-apoptotic and anti-inflammatory effects of baicalein. These results provide new insight into the possible molecular mechanisms by which baicalein protects against atherogenesis by NO-related pathways.
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Affiliation(s)
- Shih-Hung Chan
- Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ching-Hsia Hung
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jhih-Yuan Shih
- Department of Internal Medicine, Chi-Mei Hospital, Tainan, Taiwan
| | - Pei-Ming Chu
- Department of Anatomy, School of Medicine, China Medical University, Taichung, Taiwan
| | - Yung-Hsin Cheng
- Department of Education and Research, Taipei City Hospital, Taipei, Taiwan
| | - Yi-Ju Tsai
- Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Huei-Chen Lin
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Physical Therapy, Shu-Zen Junior College Of Medicine and Management, Kaohsiung, Taiwan
| | - Kun-Ling Tsai
- Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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13
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Pihán P, Carreras-Sureda A, Hetz C. BCL-2 family: integrating stress responses at the ER to control cell demise. Cell Death Differ 2017. [PMID: 28622296 DOI: 10.1038/cdd.2017.82] [Citation(s) in RCA: 173] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In the last decade, the endoplasmic reticulum (ER) has emerged as a central organelle regulating the core mitochondrial apoptosis pathway. At the ER membrane, a variety of stress signals are integrated toward determining cell fate, involving a complex cross talk between key homeostatic pathways including the unfolded protein response, autophagy, calcium signaling and mitochondrial bioenergetics. In this context, key regulators of cell death of the BCL-2 and TMBIM/BI-1 family of proteins have relevant functions as stress rheostats mediated by the formation of distinct protein complexes that regulate the switch between adaptive and proapoptotic phases under stress. Here, we overview recent advances on our molecular understanding of how the apoptotic machinery integrates stress signals toward cell fate decisions upstream of the mitochondrial gateway of death.
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Affiliation(s)
- Philippe Pihán
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Faculty of Medicine, Center for Geroscience, Brain Health and Metabolism, University of Chile, Santiago, Chile
| | - Amado Carreras-Sureda
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Faculty of Medicine, Center for Geroscience, Brain Health and Metabolism, University of Chile, Santiago, Chile
| | - Claudio Hetz
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Faculty of Medicine, Center for Geroscience, Brain Health and Metabolism, University of Chile, Santiago, Chile.,Buck Institute for Research on Aging, Novato, CA 94945, USA.,Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston MA 02115, USA
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14
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Danby PM, Lombardi C, Meanwell M, Fyles T. Electrogenic transport by lipophilic guanidinium salts as anion carriers in bilayer membranes. Supramol Chem 2017. [DOI: 10.1080/10610278.2017.1299865] [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: 10/20/2022]
Affiliation(s)
- Phillip M. Danby
- Department of Chemistry, University of Victoria, Victoria, Canada
| | | | - Michael Meanwell
- Department of Chemistry, University of Victoria, Victoria, Canada
| | - Thomas Fyles
- Department of Chemistry, University of Victoria, Victoria, Canada
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15
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BH3 mimetic-elicited Ca 2+ signals in pancreatic acinar cells are dependent on Bax and can be reduced by Ca 2+-like peptides. Cell Death Dis 2017; 8:e2640. [PMID: 28252652 PMCID: PMC5386550 DOI: 10.1038/cddis.2017.41] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/20/2016] [Accepted: 01/11/2017] [Indexed: 02/07/2023]
Abstract
BH3 mimetics are small-molecule inhibitors of B-cell lymphoma-2 (Bcl-2) and Bcl-xL, which disrupt the heterodimerisation of anti- and pro-apoptotic Bcl-2 family members sensitising cells to apoptotic death. These compounds have been developed as anti-cancer agents to counteract increased levels of Bcl-2 proteins often present in cancer cells. Application of a chemotherapeutic drug supported with a BH3 mimetic has the potential to overcome drug resistance in cancers overexpressing anti-apoptotic Bcl-2 proteins and thus increase the success rate of the treatment. We have previously shown that the BH3 mimetics, BH3I-2' and HA14-1, induce Ca2+ release from intracellular stores followed by a sustained elevation of the cytosolic Ca2+ concentration. Here we demonstrate that loss of Bax, but not Bcl-2 or Bak, inhibits this sustained Ca2+ elevation. What is more, in the absence of Bax, thapsigargin-elicited responses were decreased; and in two-photon-permeabilised bax-/- cells, Ca2+ loss from the ER was reduced compared to WT cells. The Ca2+-like peptides, CALP-1 and CALP-3, which activate EF hand motifs of Ca2+-binding proteins, significantly reduced excessive Ca2+ signals and necrosis caused by two BH3 mimetics: BH3I-2' and gossypol. In the presence of CALP-1, cell death was shifted from necrotic towards apoptotic, whereas CALP-3 increased the proportion of live cells. Importantly, neither of the CALPs markedly affected physiological Ca2+ signals elicited by ACh, or cholecystokinin. In conclusion, the reduction in passive ER Ca2+ leak in bax-/- cells as well as the fact that BH3 mimetics trigger substantial Ca2+ signals by liberating Bax, indicate that Bax may regulate Ca2+ leak channels in the ER. This study also demonstrates proof-of-principle that pre-activation of EF hand Ca2+-binding sites by CALPs can be used to ameliorate excessive Ca2+ signals caused by BH3 mimetics and shift necrotic death towards apoptosis.
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Gupta R, Ghosh S. JNK3 phosphorylates Bax protein and induces ability to form pore on bilayer lipid membrane. BIOCHIMIE OPEN 2017; 4:41-46. [PMID: 29450140 PMCID: PMC5801821 DOI: 10.1016/j.biopen.2017.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/01/2017] [Indexed: 11/15/2022]
Abstract
Bax is a pro-apoptotic cytosolic protein. In this work native (unphosphorylated) and JNK3 phosphorylated Bax proteins are studied on artificial bilayer membranes for pore formation. Phosphorylated Bax formed pore on the bilayer lipid membrane whereas native one does not. In cells undergoing apoptosis the pore formed by the phosphorylated Bax could be important in cytochrome c release from the mitochondrial intermembrane space to the cytosol. The low conductance (1.5 nS) of the open state of the phosphorylated Bax pore corresponds to pore diameter of 0.9 nm which is small to release cytochrome c (∼3.4 nm). We hypothesized that JNK3 phosphorylated Bax protein can form bigger pores after forming complexes with other mitochondrial proteins like VDAC, t-Bid etc. to release cytochrome c.
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Affiliation(s)
- Rajeev Gupta
- Department of Physiology, All India Institute of Medical Sciences, India
| | - Subhendu Ghosh
- Department of Biophysics, University of Delhi South Campus, India
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17
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Kwegyir-Afful AK, Ramalingam S, Purushottamachar P, Ramamurthy VP, Njar VC. Galeterone and VNPT55 induce proteasomal degradation of AR/AR-V7, induce significant apoptosis via cytochrome c release and suppress growth of castration resistant prostate cancer xenografts in vivo. Oncotarget 2015; 6:27440-60. [PMID: 26196320 PMCID: PMC4695001 DOI: 10.18632/oncotarget.4578] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 07/03/2015] [Indexed: 02/04/2023] Open
Abstract
Galeterone (Gal) is a first-in-class multi-target oral small molecule that will soon enter pivotal phase III clinical trials in castration resistant prostate cancer (CRPC) patients. Gal disrupts androgen receptor (AR) signaling via inhibition of CYP17, AR antagonism and AR degradation. Resistance to current therapy is attributed to up-regulation of full-length AR (fAR), splice variants AR (AR-Vs) and AR mutations. The effects of gal and VNPT55 were analyzed on f-AR and AR-Vs (AR-V7/ARv567es) in LNCaP, CWR22Rv1 and DU145 (transfected with AR-Vs) human PC cells in vitro and CRPC tumor xenografts. Galeterone/VNPT55 decreased fAR/AR-V7 mRNA levels and implicates Mdm2/CHIP enhanced ubiquitination of posttranslational modified receptors, targeting them for proteasomal degradation. Gal and VNPT55 also induced significant apoptosis in PC cells via increased Bax/Bcl2 ratio, cytochrome-c release with concomitant cleavage of caspase 3 and PARP. More importantly, gal and VNPT55 exhibited strong in vivo anti-CRPC activities, with no apparent host toxicities. This study demonstrate that gal and VNPT55 utilize cell-based mechanisms to deplete both fAR and AR-Vs. Importantly, the preclinical activity profiles, including profound apoptotic induction and inhibition of CRPC xenografts suggest that these agents offer considerable promise as new therapeutics for patients with CRPC and those resistant to current therapy.
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Affiliation(s)
- Andrew K. Kwegyir-Afful
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
- Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
| | - Senthilmurugan Ramalingam
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
- Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
| | - Puranik Purushottamachar
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
- Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
| | - Vidya P. Ramamurthy
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
- Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
| | - Vincent C.O. Njar
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
- Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
- Marlene Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201-1559, USA
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18
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Vanwalleghem G, Fontaine F, Lecordier L, Tebabi P, Klewe K, Nolan DP, Yamaryo-Botté Y, Botté C, Kremer A, Burkard GS, Rassow J, Roditi I, Pérez-Morga D, Pays E. Coupling of lysosomal and mitochondrial membrane permeabilization in trypanolysis by APOL1. Nat Commun 2015; 6:8078. [PMID: 26307671 PMCID: PMC4560804 DOI: 10.1038/ncomms9078] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 07/15/2015] [Indexed: 12/21/2022] Open
Abstract
Humans resist infection by the African parasite Trypanosoma brucei owing to the trypanolytic activity of the serum apolipoprotein L1 (APOL1). Following uptake by endocytosis in the parasite, APOL1 forms pores in endolysosomal membranes and triggers lysosome swelling. Here we show that APOL1 induces both lysosomal and mitochondrial membrane permeabilization (LMP and MMP). Trypanolysis coincides with MMP and consecutive release of the mitochondrial TbEndoG endonuclease to the nucleus. APOL1 is associated with the kinesin TbKIFC1, of which both the motor and vesicular trafficking VHS domains are required for MMP, but not for LMP. The presence of APOL1 in the mitochondrion is accompanied by mitochondrial membrane fenestration, which can be mimicked by knockdown of a mitochondrial mitofusin-like protein (TbMFNL). The BH3-like peptide of APOL1 is required for LMP, MMP and trypanolysis. Thus, trypanolysis by APOL1 is linked to apoptosis-like MMP occurring together with TbKIFC1-mediated transport of APOL1 from endolysosomal membranes to the mitochondrion. The human serum protein apolipoprotein L1 (APOL1) is taken up by trypanosomes where it triggers cell death, forming pores in endolysosomal membranes. Vanwalleghem et al. show that APOL1 triggers both lysosomal and mitochondrial membrane permeabilization, and that the latter is responsible for trypanolysis.
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Affiliation(s)
- Gilles Vanwalleghem
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), 12 rue des Prof Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Frédéric Fontaine
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), 12 rue des Prof Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Laurence Lecordier
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), 12 rue des Prof Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Patricia Tebabi
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), 12 rue des Prof Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Kristoffer Klewe
- Institute of Biochemistry and Pathobiochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Derek P Nolan
- Molecular Parasitology Group, School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
| | - Yoshiki Yamaryo-Botté
- Apicolipid Group, CNRS, Laboratoire Adaptation et Pathogénie des Microorganismes UMR5163/ Institut Albert Bonniot CRI Inserm/UJF U823, CNRS, Institut Jean Roget, 38700 La Tronche, France
| | - Cyrille Botté
- Apicolipid Group, CNRS, Laboratoire Adaptation et Pathogénie des Microorganismes UMR5163/ Institut Albert Bonniot CRI Inserm/UJF U823, CNRS, Institut Jean Roget, 38700 La Tronche, France
| | - Anneke Kremer
- IRC/VIB Bio Imaging Core, Gent, Technologiepark 927, B-9052 Gent, Belgium
| | | | - Joachim Rassow
- Institute of Biochemistry and Pathobiochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Isabel Roditi
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012 Bern, Switzerland
| | - David Pérez-Morga
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), 12 rue des Prof Jeener et Brachet, B-6041 Gosselies, Belgium.,Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles (ULB), 8 rue Adrienne Bolland, B-6041 Gosselies, Belgium
| | - Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), 12 rue des Prof Jeener et Brachet, B-6041 Gosselies, Belgium.,Walloon Excellence in Life sciences and Biotechnology (WELBIO), Wavre, Belgium
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19
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Rajan S, Choi M, Nguyen QT, Ye H, Liu W, Toh HT, Kang C, Kamariah N, Li C, Huang H, White C, Baek K, Grüber G, Yoon HS. Structural transition in Bcl-xL and its potential association with mitochondrial calcium ion transport. Sci Rep 2015; 5:10609. [PMID: 26023881 PMCID: PMC4448555 DOI: 10.1038/srep10609] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 04/21/2015] [Indexed: 11/17/2022] Open
Abstract
Bcl-2 family proteins are key regulators for cellular homeostasis in response to apoptotic stimuli. Bcl-xL, an antiapoptotic Bcl-2 family member, undergoes conformational transitions, which leads to two conformational states: the cytoplasmic and membrane-bound. Here we present the crystal and small-angle X-ray scattering (SAXS) structures of Bcl-xL treated with the mild detergent n-Octyl β-D-Maltoside (OM). The detergent-treated Bcl-xL forms a dimer through three-dimensional domain swapping (3DDS) by swapping helices α6-α8 between two monomers. Unlike Bax, a proapoptotic member of the Bcl-2 family, Bcl-xL is not converted to 3DDS homodimer upon binding BH3 peptides and ABT-737, a BH3 mimetic drug. We also designed Bcl-xL mutants which cannot dimerize and show that these mutants reduced mitochondrial calcium uptake in MEF cells. This illustrates the structural plasticity in Bcl-xL providing hints toward the probable molecular mechanism for Bcl-xL to play a regulatory role in mitochondrial calcium ion transport.
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Affiliation(s)
- Sreekanth Rajan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Minjoo Choi
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Quoc Toan Nguyen
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Hong Ye
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Wei Liu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Hui Ting Toh
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - CongBao Kang
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore 138669
| | - Neelagandan Kamariah
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, Singapore 138671
| | - Chi Li
- Molecular Targets Program, James Graham Brown Center and Department of Medicine, Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA
| | - Huiya Huang
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Carl White
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Kwanghee Baek
- Department of Genetic Engineering, College of Life Sciences, Kyung Hee University, Yongin-si, Gyeonggi-do, 446-701, Republic of Korea
| | - Gerhard Grüber
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, Singapore 138671
| | - Ho Sup Yoon
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
- Department of Genetic Engineering, College of Life Sciences, Kyung Hee University, Yongin-si, Gyeonggi-do, 446-701, Republic of Korea
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20
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Lee D, Kim KY, Shim MS, Kim SY, Ellisman MH, Weinreb RN, Ju WK. Coenzyme Q10 ameliorates oxidative stress and prevents mitochondrial alteration in ischemic retinal injury. Apoptosis 2015; 19:603-14. [PMID: 24337820 PMCID: PMC3938850 DOI: 10.1007/s10495-013-0956-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Coenzyme Q10 (CoQ10) acts by scavenging reactive oxygen species for protecting neuronal cells against oxidative stress in neurodegenerative diseases. We tested whether a diet supplemented with CoQ10 ameliorates oxidative stress and mitochondrial alteration, as well as promotes retinal ganglion cell (RGC) survival in ischemic retina induced by intraocular pressure elevation. A CoQ10 significantly promoted RGC survival at 2 weeks after ischemia. Superoxide dismutase 2 (SOD2) and heme oxygenase-1 (HO-1) expression were significantly increased at 12 h after ischemic injury. In contrast, the CoQ10 significantly prevented the upregulation of SOD2 and HO-1 protein expression in ischemic retina. In addition, the CoQ10 significantly blocked activation of astroglial and microglial cells in ischemic retina. Interestingly, the CoQ10 blocked apoptosis by decreasing caspase-3 protein expression in ischemic retina. Bax and phosphorylated Bad (pBad) protein expression were significantly increased in ischemic retina at 12 h. Interestingly, while CoQ10 significantly decreased Bax protein expression in ischemic retina, CoQ10 showed greater increase of pBad protein expression. Of interest, ischemic injury significantly increased mitochondrial transcription factor A (Tfam) protein expression in the retina at 12 h, however, CoQ10 significantly preserved Tfam protein expression in ischemic retina. Interestingly, there were no differences in mitochondrial DNA content among control- or CoQ10-treated groups. Our findings demonstrate that CoQ10 protects RGCs against oxidative stress by modulating the Bax/Bad-mediated mitochondrial apoptotic pathway as well as prevents mitochondrial alteration by preserving Tfam protein expression in ischemic retina. Our results suggest that CoQ10 may provide neuroprotection against oxidative stress-mediated mitochondrial alterations in ischemic retinal injury.
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Affiliation(s)
- Dongwook Lee
- Laboratory for Optic Nerve Biology, Department of Ophthalmology, Hamilton Glaucoma Center, University of California San Diego, 9415 Campus Point Drive, La Jolla, CA 92037 USA
- Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute, Chonbuk National University Hospital, Chonju, Chonbuk Republic of Korea
| | - Keun-Young Kim
- Department of Neuroscience, Center for Research on Biological Systems, National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA USA
| | - Myoung Sup Shim
- Laboratory for Optic Nerve Biology, Department of Ophthalmology, Hamilton Glaucoma Center, University of California San Diego, 9415 Campus Point Drive, La Jolla, CA 92037 USA
| | - Sang Yeop Kim
- Laboratory for Optic Nerve Biology, Department of Ophthalmology, Hamilton Glaucoma Center, University of California San Diego, 9415 Campus Point Drive, La Jolla, CA 92037 USA
| | - Mark H. Ellisman
- Department of Neuroscience, Center for Research on Biological Systems, National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA USA
| | - Robert N. Weinreb
- Laboratory for Optic Nerve Biology, Department of Ophthalmology, Hamilton Glaucoma Center, University of California San Diego, 9415 Campus Point Drive, La Jolla, CA 92037 USA
| | - Won-Kyu Ju
- Laboratory for Optic Nerve Biology, Department of Ophthalmology, Hamilton Glaucoma Center, University of California San Diego, 9415 Campus Point Drive, La Jolla, CA 92037 USA
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21
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Ning YB, Du ZQ. Role of c-Jun N-terminal kinase activation in apoptosis induced by removal of the growth factors. Cell Biol Int 2015; 39:577-83. [PMID: 25572129 DOI: 10.1002/cbin.10425] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Accepted: 12/26/2014] [Indexed: 11/11/2022]
Abstract
Apoptosis plays a crucial role for generation of lymphocyte repertoire, clonal contraction, and elimination of virus-infected cells. Since IL-3-dependent pro-B cell line Baf-3 resulted in rapid induction of apoptotic cell death upon IL-3 withdrawal, it would by very valuable for analysis of apoptosis induction by growth factor deprivation. First, we confirmed that Baf-3 cells underwent loss of mitochondrial membrane potential (ΔΨm) and apoptosis in a time-dependent manner when they were cultured in the RPMI-1640 medium without IL-3. Induction of apoptosis and loss of ΔΨm was determined by DiOC6 and annexin V staining method using flow cytometer, respectively. Deprivation of IL-3 induced upregulation of proapoptotic molecule Bax, in conjunction with slight down-regulation of anti-apoptotic molecule Bcl-xL, which was assessed by Western blotting. Since Bcl-xL-overexpressing Baf-3 cells showed some resistance to IL-3-deprivation, Bcl-xL prevents apoptosis induced by IL-3 withdrawal. Finally, a sustained JNK1 activation was observed prior to induction of apoptosis upon IL-3 deprivation. Dominat-negative form of JNK1 and JNK inhibitor sp600125 partially inhibit the apoptosis upon IL-3 deprivation, suggesting that a sustained JNK1 activation was involved in the induction of apoptosis. Together, IL-3 deprivation of IL-3-dependent cell line Baf-3 induces a sustained JNK1 activation, followed by a decline of the ratio of Bcl-xL to Bax, leading to loss of DCm, and finally apoptosis.
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Affiliation(s)
- Yue-Bao Ning
- School of Mathematics, Physics and Biology Engineering, Inner Mongolia University of Science and Technology, Baotou, 014010, China
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22
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Lee J, Miller BT, Damjanović A, Brooks BR. Constant pH Molecular Dynamics in Explicit Solvent with Enveloping Distribution Sampling and Hamiltonian Exchange. J Chem Theory Comput 2014; 10:2738-2750. [PMID: 25061443 PMCID: PMC4095908 DOI: 10.1021/ct500175m] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Indexed: 12/21/2022]
Abstract
We present a new computational approach for constant pH simulations in explicit solvent based on the combination of the enveloping distribution sampling (EDS) and Hamiltonian replica exchange (HREX) methods. Unlike constant pH methods based on variable and continuous charge models, our method is based on discrete protonation states. EDS generates a hybrid Hamiltonian of different protonation states. A smoothness parameter s is used to control the heights of energy barriers of the hybrid-state energy landscape. A small s value facilitates state transitions by lowering energy barriers. Replica exchange between EDS potentials with different s values allows us to readily obtain a thermodynamically accurate ensemble of multiple protonation states with frequent state transitions. The analysis is performed with an ensemble obtained from an EDS Hamiltonian without smoothing, s = ∞, which strictly follows the minimum energy surface of the end states. The accuracy and efficiency of this method is tested on aspartic acid, lysine, and glutamic acid, which have two protonation states, a histidine with three states, a four-residue peptide with four states, and snake cardiotoxin with eight states. The pKa values estimated with the EDS-HREX method agree well with the experimental pKa values. The mean absolute errors of small benchmark systems range from 0.03 to 0.17 pKa units, and those of three titratable groups of snake cardiotoxin range from 0.2 to 1.6 pKa units. This study demonstrates that EDS-HREX is a potent theoretical framework, which gives the correct description of multiple protonation states and good calculated pKa values.
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Affiliation(s)
- Juyong Lee
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Benjamin T Miller
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Ana Damjanović
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States ; Department of Biophysics, Johns Hopkins University , Baltimore, Maryland, United States
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
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23
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Functions of the C-terminal domains of apoptosis-related proteins of the Bcl-2 family. Chem Phys Lipids 2014; 183:77-90. [PMID: 24892727 DOI: 10.1016/j.chemphyslip.2014.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 02/06/2023]
Abstract
Bcl-2 family proteins are involved in cell homeostasis, where they regulate cell death. Some of these proteins are pro-apoptotic and others pro-survival. Moreover, many of them share a similar domain composition with several of the so-called BH domains, although some only have a BH3 domain. A C-terminal domain is present in all the multi-BH domain proteins and in some of the BH3-only ones. This C-terminal domain is hydrophobic or amphipathic, for which reason it was thought when they were discovered that they were membrane anchors. Although this is indeed one of their functions, it has since been observed that they may also serve as regulators of the function of some members of this family, such as Bax. They may also serve to recognize the target membrane of some of these proteins, which only after an apoptotic signal, are incorporated into a membrane. It has been shown that peptides that imitate the sequence of C-terminal domains can form pores and may serve as a model to design cytotoxic molecules.
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Abstract
The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.
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25
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Abstract
Bax, despite being a cytosolic protein, has the distinct ability to form channels in the mitochondrial outer membrane, which are capable of releasing proteins that initiate the execution phase of apoptosis. When studied in a planar phospholipid membrane system, full-length activated Bax can form conducting entities consistent with linearly organized three-channel units displaying steep voltage-gating (n=14) that rivals that of channels in excitable membranes. In addition, the channels display strong positive co-operativity possibly arising from the charge distribution of the voltage sensors. On the basis of functional behaviour, one of the channels in this functional triplet is oriented in the opposite direction to the others often resulting in conflicts between the effects of the electric field and the positive co-operativity of adjacent channels. The closure of the first channel occurs at positive potentials and this permits the second to close, but at negative potentials. The closure of the second channel in turn permits closure of the third, but at positive potentials. Positive co-operativity manifests itself in a number of ways including the second and the third channels opening virtually simultaneously. This extraordinary behaviour must have important, although as yet undefined, physiological roles.
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26
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Lee D, Shim MS, Kim KY, Noh YH, Kim H, Kim SY, Weinreb RN, Ju WK. Coenzyme Q10 inhibits glutamate excitotoxicity and oxidative stress-mediated mitochondrial alteration in a mouse model of glaucoma. Invest Ophthalmol Vis Sci 2014; 55:993-1005. [PMID: 24458150 DOI: 10.1167/iovs.13-12564] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE To test whether a diet supplemented with coenzyme Q10 (CoQ10) ameliorates glutamate excitotoxicity and oxidative stress-mediated retinal ganglion cell (RGC) degeneration by preventing mitochondrial alterations in the retina of glaucomatous DBA/2J mice. METHODS Preglaucomatous DBA/2J and age-matched control DBA/2J-Gpnmb(+) mice were fed with CoQ10 (1%) or a control diet daily for 6 months. The RGC survival and axon preservation were measured by Brn3a and neurofilament immunohistochemistry and by conventional transmission electron microscopy. Glial fibrillary acidic protein (GFAP), superoxide dismutase-2 (SOD2), heme oxygenase-1 (HO1), N-methyl-d-aspartate receptor (NR) 1 and 2A, and Bax and phosphorylated Bad (pBad) protein expression was measured by Western blot analysis. Apoptotic cell death was assessed by TUNEL staining. Mitochondrial DNA (mtDNA) content and mitochondrial transcription factor A (Tfam)/oxidative phosphorylation (OXPHOS) complex IV protein expression were measured by real-time PCR and Western blot analysis. RESULTS Coenzyme Q10 promoted RGC survival by approximately 29% and preserved the axons in the optic nerve head (ONH), as well as inhibited astroglial activation by decreasing GFAP expression in the retina and ONH of glaucomatous DBA/2J mice. Intriguingly, CoQ10 significantly blocked the upregulation of NR1 and NR2A, as well as of SOD2 and HO1 protein expression in the retina of glaucomatous DBA/2J mice. In addition, CoQ10 significantly prevented apoptotic cell death by decreasing Bax protein expression or by increasing pBad protein expression. More importantly, CoQ10 preserved mtDNA content and Tfam/OXPHOS complex IV protein expression in the retina of glaucomatous DBA/2J mice. CONCLUSIONS Our findings suggest that CoQ10 may be a promising therapeutic strategy for ameliorating glutamate excitotoxicity and oxidative stress in glaucomatous neurodegeneration.
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Affiliation(s)
- Dongwook Lee
- Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California, San Diego, La Jolla, California
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Fröhlich M, Dejanovic B, Kashkar H, Schwarz G, Nussberger S. S-palmitoylation represents a novel mechanism regulating the mitochondrial targeting of BAX and initiation of apoptosis. Cell Death Dis 2014; 5:e1057. [PMID: 24525733 PMCID: PMC3944235 DOI: 10.1038/cddis.2014.17] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 12/23/2013] [Accepted: 01/02/2014] [Indexed: 12/19/2022]
Abstract
The intrinsic pathway of apoptotic cell death is mainly mediated by the BCL-2-associated X (BAX) protein through permeabilization of the mitochondrial outer membrane (MOM) and the concomitant release of cytochrome c into the cytosol. In healthy, non-apoptotic cells, BAX is predominantly localized in the cytosol and exhibits a dynamic shuttle cycle between the cytosol and the mitochondria. Thus, the initial association with mitochondria represents a critical regulatory step enabling BAX to insert into MOMs, promoting the release of cytochrome c and ultimately resulting in apoptosis. However, the molecular mode of how BAX associates with MOMs and whether a cellular regulatory mechanism governs this process is poorly understood. Here we show that in both primary tissues and cultured cells, the association with MOMs and the proapoptotic action of BAX is controlled by its S-palmitoylation at Cys-126. A lack of BAX palmitoylation reduced BAX mitochondrial translocation, BAX oligomerization, caspase activity and apoptosis. Furthermore, ectopic expression of specific palmitoyl transferases in cultured healthy cells increases BAX S-palmitoylation and accelerates apoptosis, whereas malignant tumor cells show reduced BAX S-palmitoylation consistent with their reduced BAX-mediated proapoptotic activity. Our findings suggest that S-palmitoylation of BAX at Cys126 is a key regulatory process of BAX-mediated apoptosis.
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Affiliation(s)
- M Fröhlich
- Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany
| | - B Dejanovic
- Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany
| | - H Kashkar
- Institute for Medical Microbiology, Immunology and Hygiene and Center for Molecular Medicine, Cologne University, Goldenfels Strasse 19-21, Cologne 50935, Germany
| | - G Schwarz
- Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany
| | - S Nussberger
- 1] Institute of Biochemistry, Department of Chemistry and Center for Molecular Medicine, Cologne University, Zülpicher Strasse 47, Cologne 50674, Germany [2] Biophysics Department, Institute of Biology, University of Stuttgart, Pfaffenwaldring 57, Stuttgart 70550, Germany
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28
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Tian D, Wang J, Zeng X, Gu K, Qiu C, Yang X, Zhou Z, Goh M, Luo Y, Murata-Hori M, White FF, Yin Z. The rice TAL effector-dependent resistance protein XA10 triggers cell death and calcium depletion in the endoplasmic reticulum. THE PLANT CELL 2014; 26:497-515. [PMID: 24488961 PMCID: PMC3963592 DOI: 10.1105/tpc.113.119255] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 12/30/2013] [Accepted: 01/13/2014] [Indexed: 05/19/2023]
Abstract
The recognition between disease resistance (R) genes in plants and their cognate avirulence (Avr) genes in pathogens can produce a hypersensitive response of localized programmed cell death. However, our knowledge of the early signaling events of the R gene-mediated hypersensitive response in plants remains limited. Here, we report the cloning and characterization of Xa10, a transcription activator-like (TAL) effector-dependent R gene for resistance to bacterial blight in rice (Oryza sativa). Xa10 contains a binding element for the TAL effector AvrXa10 (EBEAvrXa10) in its promoter, and AvrXa10 specifically induces Xa10 expression. Expression of Xa10 induces programmed cell death in rice, Nicotiana benthamiana, and mammalian HeLa cells. The Xa10 gene product XA10 localizes as hexamers in the endoplasmic reticulum (ER) and is associated with ER Ca(2+) depletion in plant and HeLa cells. XA10 variants that abolish programmed cell death and ER Ca(2+) depletion in N. benthamiana and HeLa cells also abolish disease resistance in rice. We propose that XA10 is an inducible, intrinsic terminator protein that triggers programmed cell death by a conserved mechanism involving disruption of the ER and cellular Ca(2+) homeostasis.
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Affiliation(s)
- Dongsheng Tian
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Junxia Wang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Xuan Zeng
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Republic of Singapore
| | - Keyu Gu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Chengxiang Qiu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Xiaobei Yang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Zhiyun Zhou
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Meiling Goh
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Yanchang Luo
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Maki Murata-Hori
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
| | - Frank F. White
- Department of Plant Pathology, Kansas State University, Manhattan, Kansas 66506
| | - Zhongchao Yin
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Republic of Singapore
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Jonas EA. Contributions of Bcl-xL to acute and long term changes in bioenergetics during neuronal plasticity. Biochim Biophys Acta Mol Basis Dis 2013; 1842:1168-78. [PMID: 24240091 DOI: 10.1016/j.bbadis.2013.11.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 12/23/2022]
Abstract
Mitochondria manufacture and release metabolites and manage calcium during neuronal activity and synaptic transmission, but whether long term alterations in mitochondrial function contribute to the neuronal plasticity underlying changes in organism behavior patterns is still poorly understood. Although normal neuronal plasticity may determine learning, in contrast a persistent decline in synaptic strength or neuronal excitability may portend neurite retraction and eventual somatic death. Anti-death proteins such as Bcl-xL not only provide neuroprotection at the neuronal soma during cell death stimuli, but also appear to enhance neurotransmitter release and synaptic growth and development. It is proposed that Bcl-xL performs these functions through its ability to regulate mitochondrial release of bioenergetic metabolites and calcium, and through its ability to rapidly alter mitochondrial positioning and morphology. Bcl-xL also interacts with proteins that directly alter synaptic vesicle recycling. Bcl-xL translocates acutely to sub-cellular membranes during neuronal activity to achieve changes in synaptic efficacy. After stressful stimuli, pro-apoptotic cleaved delta N Bcl-xL (ΔN Bcl-xL) induces mitochondrial ion channel activity leading to synaptic depression and this is regulated by caspase activation. During physiological states of decreased synaptic stimulation, loss of mitochondrial Bcl-xL and low level caspase activation occur prior to the onset of long term decline in synaptic efficacy. The degree to which Bcl-xL changes mitochondrial membrane permeability may control the direction of change in synaptic strength. The small molecule Bcl-xL inhibitor ABT-737 has been useful in defining the role of Bcl-xL in synaptic processes. Bcl-xL is crucial to the normal health of neurons and synapses and its malfunction may contribute to neurodegenerative disease.
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Affiliation(s)
- Elizabeth A Jonas
- Dept. of Internal Medicine, P.O. Box 208001, Yale University School of Medicine, New Haven, CT 06520, USA; Dept. of Neurobiology, P.O. Box 208020, Yale University School of Medicine, New Haven, CT 06520, USA.
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Weber K, Harper N, Schwabe J, Cohen G. BIM-mediated membrane insertion of the BAK pore domain is an essential requirement for apoptosis. Cell Rep 2013; 5:409-20. [PMID: 24120870 PMCID: PMC3898696 DOI: 10.1016/j.celrep.2013.09.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 05/14/2013] [Accepted: 09/06/2013] [Indexed: 12/02/2022] Open
Abstract
BAK activation represents a key step during apoptosis, but how it converts into a mitochondria-permeabilizing pore remains unclear. By further delineating the structural rearrangements involved, we reveal that BAK activation progresses through a series of independent steps: BH3-domain exposure, N-terminal change, oligomerization, and membrane insertion. Employing a “BCL-XL-addiction” model, we show that neutralization of BCL-XL by the BH3 mimetic ABT-737 resulted in death only when cells were reconstituted with BCL-XL:BAK, but not BCL-2/ BCL-XL:BIM complexes. Although this resembles the indirect model, release of BAK from BCL-XL did not result in spontaneous adoption of the pore conformation. Commitment to apoptosis required association of the direct activator BIM with oligomeric BAK promoting its conversion to a membrane-inserted pore. The sequential nature of this cascade provides multiple opportunities for other BCL-2 proteins to interfere with or promote BAK activation and unites aspects of the indirect and direct activation models. A BH3 mimetic displaces BAK from BCL-XL consistent with the indirect activation model Released BAK undergoes a series of distinct independent conformational changes Oligomerization is not the final step in the activation cascade BIM promotes pre-pore-to-pore conversion supporting the “direct” activation model
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Affiliation(s)
- Kathrin Weber
- MRC Toxicology Unit, University of Leicester, Hodgkin Building, Leicester LE1 9HN, UK
| | - Nicholas Harper
- MRC Toxicology Unit, University of Leicester, Hodgkin Building, Leicester LE1 9HN, UK
| | - John Schwabe
- Department of Biochemistry, University of Leicester, Henry Wellcome Building, Leicester LE1 9HN, UK
| | - Gerald M. Cohen
- MRC Toxicology Unit, University of Leicester, Hodgkin Building, Leicester LE1 9HN, UK
- Department of Biochemistry, University of Leicester, Henry Wellcome Building, Leicester LE1 9HN, UK
- Corresponding author
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Karch J, Kwong JQ, Burr AR, Sargent MA, Elrod JW, Peixoto PM, Martinez-Caballero S, Osinska H, Cheng EHY, Robbins J, Kinnally KW, Molkentin JD. Bax and Bak function as the outer membrane component of the mitochondrial permeability pore in regulating necrotic cell death in mice. eLife 2013; 2:e00772. [PMID: 23991283 PMCID: PMC3755340 DOI: 10.7554/elife.00772] [Citation(s) in RCA: 209] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 07/24/2013] [Indexed: 12/13/2022] Open
Abstract
A critical event in ischemia-based cell death is the opening of the mitochondrial permeability transition pore (MPTP). However, the molecular identity of the components of the MPTP remains unknown. Here, we determined that the Bcl-2 family members Bax and Bak, which are central regulators of apoptotic cell death, are also required for mitochondrial pore-dependent necrotic cell death by facilitating outer membrane permeability of the MPTP. Loss of Bax/Bak reduced outer mitochondrial membrane permeability and conductance without altering inner membrane MPTP function, resulting in resistance to mitochondrial calcium overload and necrotic cell death. Reconstitution with mutants of Bax that cannot oligomerize and form apoptotic pores, but still enhance outer membrane permeability, permitted MPTP-dependent mitochondrial swelling and restored necrotic cell death. Our data predict that the MPTP is an inner membrane regulated process, although in the absence of Bax/Bak the outer membrane resists swelling and prevents organelle rupture to prevent cell death. DOI:http://dx.doi.org/10.7554/eLife.00772.001 In all multicellular plants and animals, cells are continuously dying and being replaced. There are a number of different types of cell death, but two of the best studied are apoptosis and necrosis. Apoptosis, sometimes referred to as ‘cell suicide’, is a form of programmed cell death that is generally beneficial to the organism. Necrosis, however, occurs whenever cells are damaged—for example, due to a lack of oxygen—and can trigger harmful inflammation in surrounding tissue. Although the processes leading up to apoptosis and necrosis are very different, they both involve regulated changes in mitochondria—the organelles that supply cells with chemical energy. Mitochondria have a distinctive appearance, being enclosed by two membranes, the innermost of which is highly folded. During apoptosis, large pores form in the outer membranes of mitochondria. These pores are generated by two proteins—Bax and Bak—and they enable the mitochondrion to release proteins that activate processes involved in apoptosis. Pores also form in the mitochondrial membrane during necrosis. However, these mitochondrial permeability transition pores (MPTPs) occur simultaneously in both the inner and outer membranes and are thought to lead to swelling and rupture of mitochondria. Now, Karch et al. have shown that Bax and Bak are also involved in the formation of these permeability pores that underlie necrosis. When mouse cells that had been genetically modified to lack Bak and Bax were grown in cell culture, they were found to be resistant to substances that normally induce necrosis. Instead, their mitochondria continued to function normally, suggesting that MPTPs cannot form in the absence of Bak and Bax. Karch et al. then generated mice with heart cells that lack Bax and Bak, and deprived their hearts of oxygen to simulate a heart attack. Compared to normal mice, the genetically modified animals experienced less damage to their heart muscle, suggesting that the absence of Bax and Bak prevents cell death due to necrosis. If Bax and Bak are involved in both apoptosis and necrosis, inhibiting them could be a powerful therapeutic approach for preventing all forms of cell death during heart attacks or in certain degenerative diseases. DOI:http://dx.doi.org/10.7554/eLife.00772.002
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Affiliation(s)
- Jason Karch
- Department of Pediatrics , Cincinnati Children's Hospital Medical Center, University of Cincinnati , Cincinnati , United States
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Negoda A, Kim KJ, Crandall ED, Worden RM. Polystyrene nanoparticle exposure induces ion-selective pores in lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2215-22. [PMID: 23747366 DOI: 10.1016/j.bbamem.2013.05.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 05/22/2013] [Accepted: 05/27/2013] [Indexed: 12/29/2022]
Abstract
A diverse range of molecular interactions can occur between engineered nanomaterials (ENM) and biomembranes, some of which could lead to toxic outcomes following human exposure to ENM. In this study, we adapted electrophysiology methods to investigate the ability of 20nm polystyrene nanoparticles (PNP) to induce pores in model bilayer lipid membranes (BLM) that mimic biomembranes. PNP charge was varied using PNP decorated with either positive (amidine) groups or negative (carboxyl) groups, and BLM charge was varied using dioleoyl phospholipids having cationic (ethylphosphocholine), zwitterionic (phosphocholine), or anionic (phosphatidic acid) headgroups. Both positive and negative PNP induced BLM pores for all lipid compositions studied, as evidenced by current spikes and integral conductance. Stable PNP-induced pores exhibited ion selectivity, with the highest selectivity for K(+) (PK/PCl~8.3) observed when both the PNP and lipids were negatively charged, and the highest selectivity for Cl(-) (PK/PCl~0.2) observed when both the PNP and lipids were positively charged. This trend is consistent with the finding that selectivity for an ion in channel proteins is imparted by oppositely charged functional groups within the channel's filter region. The PK/PCl value was unaffected by the voltage-ramp method, the pore conductance, or the side of the BLM to which the PNP were applied. These results demonstrate for the first time that PNP can induce ion-selective pores in BLM, and that the degree of ion selectivity is influenced synergistically by the charges of both the lipid headgroups and functional groups on the PNP.
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Affiliation(s)
- Alexander Negoda
- Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, MI 48824, USA.
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Niu CC, Lin SS, Yuan LJ, Chen LH, Wang IC, Tsai TT, Lai PL, Chen WJ. Hyperbaric oxygen treatment suppresses MAPK signaling and mitochondrial apoptotic pathway in degenerated human intervertebral disc cells. J Orthop Res 2013; 31:204-9. [PMID: 22886767 DOI: 10.1002/jor.22209] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 07/16/2012] [Indexed: 02/04/2023]
Abstract
Nucleus pulposus cells (NPCs) from degenerating discs produce catabolic and inflammatory factors, including interleukin (IL)-1 and nitric oxide (NO). Enhanced production of NO has been implicated in the apoptosis of degenerating disc cells. This study evaluates the effects of hyperbaric oxygen (HBO) on degenerated human NPCs. All hyperoxic cells were exposed to 100% O(2) at 2.5 atmospheres absolute (ATA). Phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) in NPCs was detected using the phosphor-kinase array kit. RNA was isolated for real-time polymerase chain reaction (PCR) analysis of aggrecan and type II collagen gene expression. The levels of IL- 1β and NO were quantified by enzyme-linked immunosorbent assay (ELISA). To identify the HBO-induced anti-apoptotic pathways, expression of Bcl-2 and Bax proteins as well as activation of cysteine-containing aspartate-specific proteases (caspases) 3, 8, and 9 was evaluated using Western blotting after HBO treatment. Our data showed that HBO treatment decreased the expression of IL-1β, suppressed phosphorylation of ERK1/2, JNK, and p38 MAPK, decreased synthesis of NO, and increased the gene expression of aggrecan and type II collagen in NPCs as compared with the atmospheric treatment. HBO up-regulated the ratio of Bcl-2 to Bax expression and reduced the activity of caspases 9 and 3 but not of caspase 8, indicating a selective effect over the mitochondrial apoptosis pathway in degenerated NPCs. These results support our hypothesis that HBO treatment suppresses MAPK signaling and mitochondrial apoptotic pathway in degenerated human intervertebral disc cells.
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Affiliation(s)
- Chi-Chien Niu
- Department of Orthopaedic Surgery, Hyperbaric Oxygen Therapy Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
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Garg P, Nemec KN, Khaled AR, Tatulian SA. Transmembrane pore formation by the carboxyl terminus of Bax protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:732-42. [DOI: 10.1016/j.bbamem.2012.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 07/29/2012] [Accepted: 08/07/2012] [Indexed: 12/29/2022]
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Bonneau B, Prudent J, Popgeorgiev N, Gillet G. Non-apoptotic roles of Bcl-2 family: the calcium connection. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1755-65. [PMID: 23360981 DOI: 10.1016/j.bbamcr.2013.01.021] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 01/11/2013] [Accepted: 01/12/2013] [Indexed: 01/06/2023]
Abstract
The existence of the bcl-2 (B-cell lymphoma-2) gene was reported nearly 30 years ago. Yet, Bcl-2 family group of proteins still surprises us with their structural and functional diversity. Since the discovery of the Bcl-2 family of proteins as one of the main apoptosis judges, the precise mechanism of their action remains a hot topic of intensive scientific research and debates. Although extensive work has been performed on the role of mitochondria in apoptosis, more and more studies point out an implication of the endoplasmic reticulum in this process. Interestingly, Bcl-2 family proteins could be localized to both the mitochondria and the endoplasmic reticulum highlighting their crucial role in apoptosis control. In particular, in these organelles Bcl-2 proteins seem to be involved in calcium homeostasis regulation although the mechanisms underlying this function are still misunderstood. We now assume with high degree of certainty that the majority of Bcl-2 family members take part not only in apoptosis regulation but also in other processes important for the cell physiology briefly denominated as "non-apoptotic" functions. Drawing a complete and comprehensive image of Bcl-2 family requires the understanding of their implications in all cellular processes. Here, we review the current knowledge on the control of calcium homeostasis by the Bcl-2 family at the endoplasmic reticulum and at the mitochondria. Then we focus on the non-apoptotic functions of the Bcl-2 proteins in relation with the regulation of this versatile intracellular messenger. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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Siemen D, Ziemer M. What is the nature of the mitochondrial permeability transition poreand What is it Not? IUBMB Life 2013; 65:255-62. [DOI: 10.1002/iub.1130] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 12/07/2012] [Indexed: 12/23/2022]
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Bleicken S, Wagner C, García-Sáez A. Mechanistic differences in the membrane activity of Bax and Bcl-xL correlate with their opposing roles in apoptosis. Biophys J 2013; 104:421-31. [PMID: 23442864 PMCID: PMC3552256 DOI: 10.1016/j.bpj.2012.12.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 12/03/2012] [Accepted: 12/10/2012] [Indexed: 01/28/2023] Open
Abstract
Based on their membrane-permeabilizing activity in vitro, it has been proposed that Bax-like proteins induce cytochrome c release during apoptosis via pore formation. However, antiapoptotic Bcl-2 proteins, which inhibit cytochrome c release, also display pore activity in model membranes. As a consequence, a unified description that aligns the pore activity of the Bcl-2 proteins with their apoptotic function is missing. Here, we studied the mechanism of membrane binding, oligomerization, and permeabilization by pro- and antiapoptotic Bcl-2 members at the single-vesicle level. We found that proapoptotic Bax forms large, stable pores via an all-or-none mechanism that can release cytochrome c. In contrast, antiapoptotic Bcl-xL induces transient permeability alterations in pure lipid membranes that have no consequences for the mitochondrial outer membrane but inhibit Bax membrane insertion. These differences in pore activity correlate with a distinct oligomeric state of Bax and Bcl-xL in membranes and can be reproduced in isolated mitochondria. Based on our findings, we propose new models for the mechanisms of action of Bax and Bcl-xL that relate their membrane activity to their opposing roles in apoptosis and beyond.
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Affiliation(s)
- Stephanie Bleicken
- German Cancer Research Center, BioQuant, Heidelberg, Germany
- Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Corinna Wagner
- German Cancer Research Center, BioQuant, Heidelberg, Germany
- Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Ana J. García-Sáez
- German Cancer Research Center, BioQuant, Heidelberg, Germany
- Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
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Bender T, Martinou JC. Where killers meet--permeabilization of the outer mitochondrial membrane during apoptosis. Cold Spring Harb Perspect Biol 2013; 5:a011106. [PMID: 23284044 DOI: 10.1101/cshperspect.a011106] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Although mitochondria are usually considered as supporters of life, they are also involved in cellular death. Mitochondrial outer membrane permeabilization (MOMP) is a crucial event during apoptosis because it causes the release of proapoptotic factors from the mitochondrial intermembrane space to the cytosol. MOMP is mainly controlled by the Bcl-2 family of proteins, which consists of both proapoptotic and antiapoptotic members. We discuss the current understanding of how activating and inhibitory interactions within this family lead to the activation and oligomerization of MOMP effectors Bax and Bak, which result in membrane permeabilization. The order of events leading to MOMP is then highlighted step by step, emphasizing recent discoveries regarding the formation of Bax/Bak pores on the outer mitochondrial membrane. Besides the Bcl-2 proteins, the mitochondrial organelle contributes to and possibly regulates MOMP, because mitochondrial resident proteins and membrane lipids are prominently involved in the process.
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Affiliation(s)
- Tom Bender
- Department of Cell Biology, University of Geneva, 1211 Geneva 4, Switzerland
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Lee D, Kim KY, Noh YH, Chai S, Lindsey JD, Ellisman MH, Weinreb RN, Ju WK. Brimonidine blocks glutamate excitotoxicity-induced oxidative stress and preserves mitochondrial transcription factor a in ischemic retinal injury. PLoS One 2012; 7:e47098. [PMID: 23056591 PMCID: PMC3467218 DOI: 10.1371/journal.pone.0047098] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 09/10/2012] [Indexed: 11/19/2022] Open
Abstract
Glutamate excitotoxicity-induced oxidative stress have been linked to mitochondrial dysfunction in retinal ischemia and optic neuropathies including glaucoma. Brimonindine (BMD), an alpha 2-adrenergic receptor agonist, contributes to the neuroprotection of retinal ganglion cells (RGCs) against glutamate excitotoxicity or oxidative stress. However, the molecular mechanisms of BMD-associated mitochondrial preservation in RGC protection against glutamate excitotoxicity-induced oxidative stress following retinal ischemic injury remain largely unknown. Here, we tested whether activation of alpha 2 adrenergic receptor by systemic BMD treatment blocks glutamate excitotoxicity-induced oxidative stress, and preserves the expression of mitochondrial transcription factor A (Tfam) and oxidative phosphorylation (OXPHOS) complex in ischemic retina. Sprague-Dawley rats received BMD (1 mg/kg/day) or vehicle (0.9% saline) systemically and then transient ischemia was induced by acute intraocular pressure elevation. Systemic BMD treatment significantly increased RGC survival at 4 weeks after ischemia. At 24 hours, BMD significantly decreased Bax expression but increased Bcl-xL and phosphorylated Bad protein expression in ischemic retina. Importantly. BMD significantly blocked the upregulations of N-methyl-D-aspartate receptors 1 and 2A protein expression, as well as of SOD2 protein expression in ischemic retina at 24 hours. During the early neurodegeneration following ischemic injury (12–72 hours), Tfam and OXPHOS complex protein expression were significantly increased in vehicle-treated retina. At 24 hours after ischemia, Tfam immunoreactivity was increased in the outer plexiform layer, inner nuclear layer, inner plexiform layer and ganglion cell layer. Further, Tfam protein was expressed predominantly in RGCs. Finally, BMD preserved Tfam immunoreactivity in RGCs as well as Tfam/OXPHOS complex protein expression in the retinal extracts against ischemic injury. Our findings suggest that systemic BMD treatment protects RGCs by blockade of glutamate excitotoxicity-induced oxidative stress and subsequent preservation of Tfam/OXPHOS complex expression in ischemic retina.
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Affiliation(s)
- Dongwook Lee
- The Sophie and Arthur Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America
- Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute, Chonbuk National University Hospital, Jeonju, Jeonbuk, Republic of Korea
| | - Keun-Young Kim
- Center for Research on Biological Systems, National Center for Microscopy and Imaging Research, and Department of Neuroscience, University of California San Diego, La Jolla, California, United States of America
| | - You Hyun Noh
- The Sophie and Arthur Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America
| | - Stephen Chai
- The Sophie and Arthur Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America
| | - James D. Lindsey
- The Sophie and Arthur Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America
| | - Mark H. Ellisman
- Center for Research on Biological Systems, National Center for Microscopy and Imaging Research, and Department of Neuroscience, University of California San Diego, La Jolla, California, United States of America
| | - Robert N. Weinreb
- The Sophie and Arthur Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America
| | - Won-Kyu Ju
- The Sophie and Arthur Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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Artesunate induces G0/G1 cell cycle arrest and iron-mediated mitochondrial apoptosis in A431 human epidermoid carcinoma cells. Anticancer Drugs 2012; 23:606-13. [PMID: 22421370 DOI: 10.1097/cad.0b013e328350e8ac] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The anticancer effects of artesunate (ART) have been well documented. However, its potential against skin cancer has not been explored yet. Herein we reported that 60 μmol/l ART effectively inhibited A431 (human epidermoid carcinoma cells) growth but not that of HaCaT (normal human keratinocyte cells). Our results revealed that ART induced cell cycle arrest at G0/G1 phase through the downregulation of cyclin A1, cyclin B, cyclin D1, Cdk2, Cdk4, and Cdk6. This correlated with the upregulation of p21 and p27. The 5-bromodeoxyuridine incorporation assay also indicated that ART treatment reduced DNA synthesis in a time-dependent manner. Furthermore, ART induced mitochondrial apoptosis, as evidenced by annexin V/propidium iodide staining and western blot analysis. Interestingly, ART-induced apoptosis diminished under iron-deficient conditions but intensified under iron-overload conditions. Taken together, these findings demonstrated the potential of ART in treating skin cancer through the induction of G0/G1 cell cycle arrest and iron-mediated mitochondrial apoptosis and supported further investigations in other test systems.
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41
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Affiliation(s)
- Marco Colombini
- Department of Biology,
University of Maryland, College
Park, Maryland 20742, United States
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42
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Abstract
The Bcl-2 family of proteins is formed by pro- and antiapoptotic members. Together they regulate the permeabilization of the mitochondrial outer membrane, a key step in apoptosis. Their complex network of interactions both in the cytosol and on mitochondria determines the fate of the cell. In the past 2 decades, the members of the family have been identified and classified according to their function. Several competing models have been proposed to explain how the Blc-2 proteins orchestrate apoptosis signaling. However, basic aspects of the action of these proteins remain elusive. This review is focused on the biophysical mechanisms that are relevant for their action in apoptosis and on the challenging gaps in our knowledge that necessitate further exploration to finally understand how the Bcl-2 family regulates apoptosis.
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Affiliation(s)
- A J García-Sáez
- Membrane Biophysics, Max Planck Institute for Intelligent Systems, Stuttgart, Germany.
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43
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Bhat V, Kurouski D, Olenick MB, McDonald CB, Mikles DC, Deegan BJ, Seldeen KL, Lednev IK, Farooq A. Acidic pH promotes oligomerization and membrane insertion of the BclXL apoptotic repressor. Arch Biochem Biophys 2012; 528:32-44. [PMID: 22960132 DOI: 10.1016/j.abb.2012.08.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/19/2012] [Accepted: 08/20/2012] [Indexed: 01/03/2023]
Abstract
Solution pH is believed to serve as an intricate regulatory switch in the induction of apoptosis central to embryonic development and cellular homeostasis. Herein, using an array of biophysical techniques, we provide evidence that acidic pH promotes the assembly of BclXL apoptotic repressor into a megadalton oligomer with a plume-like appearance and harboring structural features characteristic of a molten globule. Strikingly, our data reveal that pH tightly modulates not only oligomerization but also ligand binding and membrane insertion of BclXL in a highly subtle manner. Thus, while oligomerization and the accompanying molten globular content of BclXL is least favorable at pH 6, both of these structural features become more pronounced under acidic and alkaline conditions. However, membrane insertion of BclXL appears to be predominantly favored under acidic conditions. In a remarkable contrast, while ligand binding to BclXL optimally occurs at pH 6, it is diminished by an order of magnitude at lower and higher pH. This reciprocal relationship between BclXL oligomerization and ligand binding lends new insights into how pH modulates functional versatility of a key apoptotic regulator and strongly argues that the molten globule may serve as an intermediate primed for membrane insertion in response to apoptotic cues.
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Affiliation(s)
- Vikas Bhat
- Department of Biochemistry and Molecular Biology, Leonard Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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44
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µ-Calpain conversion of antiapoptotic Bfl-1 (BCL2A1) into a prodeath factor reveals two distinct alpha-helices inducing mitochondria-mediated apoptosis. PLoS One 2012; 7:e38620. [PMID: 22745672 PMCID: PMC3379997 DOI: 10.1371/journal.pone.0038620] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Accepted: 05/09/2012] [Indexed: 01/09/2023] Open
Abstract
Anti-apoptotic Bfl-1 and pro-apoptotic Bax, two members of the Bcl-2 family sharing a similar structural fold, are classically viewed as antagonist regulators of apoptosis. However, both proteins were reported to be death inducers following cleavage by the cysteine protease µ-calpain. Here we demonstrate that calpain-mediated cleavage of full-length Bfl-1 induces the release of C-terminal membrane active α-helices that are responsible for its conversion into a pro-apoptotic factor. A careful comparison of the different membrane-active regions present in the Bfl-1 truncated fragments with homologous domains of Bax show that helix α5, but not α6, of Bfl-1 induces cell death and cytochrome c release from purified mitochondria through a Bax/Bak-dependent mechanism. In contrast, both helices α5 and α6 of Bax permeabilize mitochondria regardless of the presence of Bax or Bak. Moreover, we provide evidence that the α9 helix of Bfl-1 promotes cytochrome c release and apoptosis through a unique membrane-destabilizing action whereas Bax-α9 does not display such activities. Hence, despite a common 3D-structure, C-terminal toxic domains present on Bfl-1 and Bax function in a dissimilar manner to permeabilize mitochondria and induce apoptosis. These findings provide insights for designing therapeutic approaches that could exploit the cleavage of endogenous Bcl-2 family proteins or the use of Bfl-1/Bax-derived peptides to promote tumor cell clearance.
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45
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Quesada R. Membrane Transport. Supramol Chem 2012. [DOI: 10.1002/9780470661345.smc173] [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: 11/10/2022]
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46
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Zhao L, He F, Liu H, Zhu Y, Tian W, Gao P, He H, Yue W, Lei X, Ni B, Wang X, Jin H, Hao X, Lin J, Chen Q. Natural diterpenoid compound elevates expression of Bim protein, which interacts with antiapoptotic protein Bcl-2, converting it to proapoptotic Bax-like molecule. J Biol Chem 2011; 287:1054-65. [PMID: 22065578 DOI: 10.1074/jbc.m111.264481] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Overwhelming evidence indicates that Bax and Bak are indispensable for mediating cytochrome c release from mitochondria during apoptosis. Here we report a Bax/Bak-independent mechanism of cytochrome c release and apoptosis. We identified a natural diterpenoid compound that induced apoptosis in bax/bak double knock-out murine embryonic fibroblasts and substantially reduced the tumor growth from these cells implanted in mice. Treatment with the compound significantly increased expression of Bim, which migrated to mitochondria, altering the conformation of and forming oligomers with resident Bcl-2 to induce cytochrome c release and caspase activation. Importantly, purified Bim and Bcl-2 proteins cooperated to permeabilize a model mitochondrial outer membrane; this was accompanied by oligomerization of these proteins and deep embedding of Bcl-2 in the membrane. Therefore, the diterpenoid compound induces a structural and functional conversion of Bcl-2 through Bim to permeabilize the mitochondrial outer membrane, thereby inducing apoptosis independently of Bax and Bak. Because Bcl-2 family proteins play important roles in cancer development and relapse, this novel cell death mechanism can be explored for developing more effective anticancer therapeutics.
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Affiliation(s)
- Lixia Zhao
- Joint Laboratory of Apoptosis and Mitochondrial Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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47
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Lin S, Perera M, Nguyen T, Datskovskiy D, Miles M, Colombini M. Bax forms two types of channels, one of which is voltage-gated. Biophys J 2011; 101:2163-9. [PMID: 22067154 PMCID: PMC3207152 DOI: 10.1016/j.bpj.2011.09.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 09/18/2011] [Accepted: 09/20/2011] [Indexed: 01/23/2023] Open
Abstract
When activated, the proapoptotic protein Bax permeabilizes the mitochondrial outer membrane, allowing the release of proteins into the cytosol and thus initiating the execution phase of apoptosis. When activated Bax was reconstituted into phospholipid membranes, we discovered a new, to our knowledge, property of Bax channels: voltage gating. We also found that the same Bax sample under the same experimental conditions could give rise to two radically different channels: Type A, which is small, well behaved, homogeneous, and voltage-gated, and Type B, which is large, noisy, and voltage-independent. One Type B channel can be converted irreversibly into a population of Type A channels by the addition of La(3+). This conversion process appears to involve a two-dimensional budding mechanism. The existence of these two types of Bax channels suggests a process for controlling the degree of mitochondrial outer membrane permeabilization.
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Affiliation(s)
| | | | | | | | | | - Marco Colombini
- Department of Biology, University of Maryland, College Park, Maryland
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48
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McCommis KS, Baines CP. The role of VDAC in cell death: friend or foe? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1444-50. [PMID: 22062421 DOI: 10.1016/j.bbamem.2011.10.025] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 10/18/2011] [Accepted: 10/24/2011] [Indexed: 11/16/2022]
Abstract
As the voltage-dependent anion channel (VDAC) forms the interface between mitochondria and the cytosol, its importance in metabolism is well understood. However, research on VDAC's role in cell death is a rapidly growing field, unfortunately with much confusing and contradictory results. The fact that VDAC plays a role in outer mitochondrial membrane permeabilization is undeniable, however, the mechanisms behind this remain very poorly understood. In this review, we will summarize the studies that show evidence of VDAC playing a role in cell death. To begin, we will discuss the evidence for and against VDAC's involvement in mitochondrial permeability transition (MPT) and attempt to clarify that VDAC is not an essential component of the MPT pore (MPTP). Next, we will evaluate the remaining literature on VDAC in cell death which can be divided into three models: proapoptotic agents escaping through VDAC, VDAC homo- or hetero-oligomerization, or VDAC closure resulting in outer mitochondrial membrane permeabilization through an unknown pathway. We will then discuss the growing list of modulators of VDAC activity that have been associated with induction/protection against cell death. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.
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Affiliation(s)
- Kyle S McCommis
- Department of Biomedical Sciences, University of Missouri, USA
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49
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Martinou JC, Youle RJ. Mitochondria in apoptosis: Bcl-2 family members and mitochondrial dynamics. Dev Cell 2011; 21:92-101. [PMID: 21763611 DOI: 10.1016/j.devcel.2011.06.017] [Citation(s) in RCA: 1073] [Impact Index Per Article: 82.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 06/06/2011] [Accepted: 06/10/2011] [Indexed: 12/31/2022]
Abstract
Mitochondria participate in apoptosis through a range of mechanisms that vary between vertebrates and invertebrates. In vertebrates, they release intermembrane space proteins, such as cytochrome c, to promote caspase activation in the cytosol. This process is the result of the loss of integrity of the outer mitochondrial membrane caused by proapoptotic members of the Bcl-2 family. This event is always accompanied by a fissioning of the organelle. Fission of mitochondria has also been reported to participate in apoptosis in Drosophila and Caenorhabditis elegans. However, in these organisms, mitochondrial membrane permeabilization does not occur and the mechanism by which mitochondrial dynamics participates in cell death remains elusive.
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Affiliation(s)
- Jean-Claude Martinou
- Department of Cell Biology, University of Geneva, Faculty of Sciences, 30 quai Ernest-Ansermet, Geneva 4, Switzerland.
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50
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BAX unleashed: the biochemical transformation of an inactive cytosolic monomer into a toxic mitochondrial pore. Trends Biochem Sci 2011; 36:642-52. [PMID: 21978892 DOI: 10.1016/j.tibs.2011.08.009] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 08/26/2011] [Accepted: 08/31/2011] [Indexed: 02/07/2023]
Abstract
BAX, the BCL-2-associated X protein, is a cardinal proapoptotic member of the BCL-2 family, which regulates the critical balance between cellular life and death. Because so many medical conditions can be categorized as diseases of either too many or too few cells, dissecting the biochemistry of BCL-2 family proteins and developing pharmacological strategies to target them have become high priority scientific objectives. Here, we focus on BAX, a latent, cytosolic and monomeric protein that transforms into a lethal mitochondrial oligomer in response to cellular stress. New insights into the structural location of BAX's 'on switch', and the multi-step conformational changes that ensue upon BAX activation, are providing fresh opportunities to modulate BAX for potential benefit in human diseases characterized by pathologic cell survival or unwanted cellular demise.
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