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Gu L, Wang Y, Xie S, Liu Y, Yan J, Yin W, Luo C. UvATG6 Interacts with BAX Inhibitor 1 Proteins and Plays Critical Roles in Growth, Conidiation, and Virulence in Ustilaginoidea virens. Microbiol Spectr 2023; 11:e0489822. [PMID: 37102873 PMCID: PMC10269921 DOI: 10.1128/spectrum.04898-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 03/30/2023] [Indexed: 04/28/2023] Open
Abstract
Autophagy and apoptosis are evolutionarily conserved catabolic processes involved in regulating development and cellular homeostasis. Bax inhibitor 1 (BI-1) and autophagy protein 6 (ATG6) perform essential functions in these roles, such as cellular differentiation and virulence in various filamentous fungi. However, the functions of ATG6 and BI-1 proteins in development and virulence in the rice false smut fungus Ustilaginoidea virens are still poorly understood. In this study, UvATG6 was characterized in U. virens. The deletion of UvATG6 almost abolished autophagy in U. virens and reduced growth, conidial production and germination, and virulence. Stress tolerance assays showed that UvATG6 mutants were sensitive to hyperosmotic, salt, and cell wall integrity stresses but were insensitive to oxidative stress. Furthermore, we found that UvATG6 interacted with UvBI-1 or UvBI-1b and suppressed Bax-induced cell death. We previously found that UvBI-1 could suppress Bax-induced cell death and was a negative regulator of mycelial growth and conidiation. Unlike UvBI-1, UvBI-1b could not suppress cell death. UvBI-1b-deleted mutants exhibited decreased growth and conidiation, while the UvBI-1 and UvBI-1b double deletion reduced the phenotype, indicating that UvBI-1 and UvBI-1b antagonistically regulate mycelial growth and conidiation. In addition, the UvBI-1b and double mutants exhibited decreased virulence. Our results provide evidence of the cross talk of autophagy and apoptosis in U. virens and give clues for studying other phytopathogenic fungi. IMPORTANCE Ustilaginoidea virens causes destructive panicle disease in rice, significantly threatening agricultural production. UvATG6 is required for autophagy and contributes to growth, conidiation, and virulence in U. virens. Additionally, it interacts with the Bax inhibitor 1 proteins UvBI-1 and UvBI-1b. UvBI-1 suppresses cell death induced by Bax, unlike UvBI-1b. UvBI-1 negatively regulates growth and conidiation, while UvBI-1b is required for these phenotypes. These results indicate that UvBI-1 and UvBI-1b may antagonistically regulate growth and conidiation. In addition, both of them contribute to virulence. Additionally, our results suggest cross talk between autophagy and apoptosis, contributing to the development, adaptability, and virulence of U. virens.
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Affiliation(s)
- Lifan Gu
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yufu Wang
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Songlin Xie
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yueran Liu
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jiali Yan
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Weixiao Yin
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Chaoxi Luo
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
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2
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Zhang L, Dietsche F, Seitaj B, Rojas-Charry L, Latchman N, Tomar D, Wüst RC, Nickel A, Frauenknecht KB, Schoser B, Schumann S, Schmeisser MJ, Vom Berg J, Buch T, Finger S, Wenzel P, Maack C, Elrod JW, Parys JB, Bultynck G, Methner A. TMBIM5 loss of function alters mitochondrial matrix ion homeostasis and causes a skeletal myopathy. Life Sci Alliance 2022; 5:5/10/e202201478. [PMID: 35715207 PMCID: PMC9206080 DOI: 10.26508/lsa.202201478] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/25/2022] [Accepted: 05/31/2022] [Indexed: 01/13/2023] Open
Abstract
TMBIM5 deficiency reduces mitochondrial K+/H+ exchange. Mutation of the channel pore in mice destabilizes the protein and results in increased embryonic lethality and a skeletal myopathy. Ion fluxes across the inner mitochondrial membrane control mitochondrial volume, energy production, and apoptosis. TMBIM5, a highly conserved protein with homology to putative pH-dependent ion channels, is involved in the maintenance of mitochondrial cristae architecture, ATP production, and apoptosis. Here, we demonstrate that overexpressed TMBIM5 can mediate mitochondrial calcium uptake. Under steady-state conditions, loss of TMBIM5 results in increased potassium and reduced proton levels in the mitochondrial matrix caused by attenuated exchange of these ions. To identify the in vivo consequences of TMBIM5 dysfunction, we generated mice carrying a mutation in the channel pore. These mutant mice display increased embryonic or perinatal lethality and a skeletal myopathy which strongly correlates with tissue-specific disruption of cristae architecture, early opening of the mitochondrial permeability transition pore, reduced calcium uptake capability, and mitochondrial swelling. Our results demonstrate that TMBIM5 is an essential and important part of the mitochondrial ion transport system machinery with particular importance for embryonic development and muscle function.
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Affiliation(s)
- Li Zhang
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | | | - Bruno Seitaj
- Department of Cellular and Molecular Medicine, KU Leuven, Laboratory of Molecular and Cellular Signaling, Leuven, Belgium
| | - Liliana Rojas-Charry
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.,Institute of Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Nadina Latchman
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Dhanendra Tomar
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Rob Ci Wüst
- Laboratory for Myology, Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Alexander Nickel
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Katrin Bm Frauenknecht
- Institute of Neuropathology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Benedikt Schoser
- Friedrich-Baur-Institute, Department of Neurology, LMU Clinic, Munich, Germany
| | - Sven Schumann
- Institute of Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Michael J Schmeisser
- Institute of Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Johannes Vom Berg
- Institute of Laboratory Animal Science, University of Zurich, Zürich, Switzerland
| | - Thorsten Buch
- Institute of Laboratory Animal Science, University of Zurich, Zürich, Switzerland
| | - Stefanie Finger
- Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Philip Wenzel
- Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.,Department of Cardiology, Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Mainz, Germany
| | - Christoph Maack
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - John W Elrod
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Jan B Parys
- Department of Cellular and Molecular Medicine, KU Leuven, Laboratory of Molecular and Cellular Signaling, Leuven, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, KU Leuven, Laboratory of Molecular and Cellular Signaling, Leuven, Belgium
| | - Axel Methner
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
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3
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Pihán P, Lisbona F, Borgonovo J, Edwards-Jorquera S, Nunes-Hasler P, Castillo K, Kepp O, Urra H, Saarnio S, Vihinen H, Carreras-Sureda A, Forveille S, Sauvat A, De Giorgis D, Pupo A, Rodríguez DA, Quarato G, Sagredo A, Lourido F, Letai A, Latorre R, Kroemer G, Demaurex N, Jokitalo E, Concha ML, Glavic Á, Green DR, Hetz C. Control of lysosomal-mediated cell death by the pH-dependent calcium channel RECS1. SCIENCE ADVANCES 2021; 7:eabe5469. [PMID: 34767445 PMCID: PMC8589314 DOI: 10.1126/sciadv.abe5469] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 09/24/2021] [Indexed: 05/27/2023]
Abstract
Programmed cell death is regulated by the balance between activating and inhibitory signals. Here, we have identified RECS1 (responsive to centrifugal force and shear stress 1) [also known as TMBIM1 (transmembrane BAX inhibitor motif containing 1)] as a proapoptotic member of the TMBIM family. In contrast to other proteins of the TMBIM family, RECS1 expression induces cell death through the canonical mitochondrial apoptosis pathway. Unbiased screening indicated that RECS1 sensitizes cells to lysosomal perturbations. RECS1 localizes to lysosomes, where it regulates their acidification and calcium content, triggering lysosomal membrane permeabilization. Structural modeling and electrophysiological studies indicated that RECS1 is a pH-regulated calcium channel, an activity that is essential to trigger cell death. RECS1 also sensitizes whole animals to stress in vivo in Drosophila melanogaster and zebrafish models. Our results unveil an unanticipated function for RECS1 as a proapoptotic component of the TMBIM family that ignites cell death programs at lysosomes.
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Affiliation(s)
- Philippe Pihán
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Fernanda Lisbona
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Center for Genome Regulation, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Janina Borgonovo
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Program of Integrative Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | | | - Paula Nunes-Hasler
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Oliver Kepp
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France
| | - Hery Urra
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Suvi Saarnio
- Electron Microscopy Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Electron Microscopy Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Amado Carreras-Sureda
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Sabrina Forveille
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France
| | - Allan Sauvat
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France
| | - Daniela De Giorgis
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Amaury Pupo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Diego A. Rodríguez
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Giovanni Quarato
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Alfredo Sagredo
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Fernanda Lourido
- Center for Genome Regulation, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Anthony Letai
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Dana Building, Room DA-520, Boston, MA 02215-02115, USA
- Harvard Medical School, Boston, MA 02215, USA
- Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02215, USA
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Guido Kroemer
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France
- Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
- Suzhou Institute for Systems Medicine, Chinese Academy of Medical Sciences, Suzhou, China
- Karolinska Institutet, Department of Women’s and Children’s Health, Karolinska University Hospital, Stockholm, Sweden
| | - Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Centro de Investigación de Estudios Avanzados, Universidad Católica del Maule, Talca, Chile
| | - Eija Jokitalo
- Electron Microscopy Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Miguel L. Concha
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Program of Integrative Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Álvaro Glavic
- Center for Genome Regulation, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Douglas R. Green
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Buck Institute for Research on Aging, Novato, CA 94945, USA
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4
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Zhang L, Buhr S, Voigt A, Methner A. The Evolutionary Conserved Transmembrane BAX Inhibitor Motif (TMBIM) Containing Protein Family Members 5 and 6 Are Essential for the Development and Survival of Drosophila melanogaster. Front Cell Dev Biol 2021; 9:666484. [PMID: 34540824 PMCID: PMC8446389 DOI: 10.3389/fcell.2021.666484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 08/16/2021] [Indexed: 11/30/2022] Open
Abstract
The mammalian Transmembrane BAX Inhibitor Motif (TMBIM) protein family consists of six evolutionarily conserved hydrophobic proteins that affect programmed cell death and the regulation of intracellular calcium levels. The bacterial ortholog BsYetJ is a pH-dependent calcium channel. We here identified seven TMBIM family members in Drosophila melanogaster and describe their expression levels in diverse tissues and developmental stages. A phylogenetic analysis revealed that CG30379 represents the ortholog of human TMBIM4 although these two proteins are much less related than TMBIM5 (CG2076 and CG1287/Mics1) and TMBIM6 (CG7188/Bi-1) to their respective orthologs. For TMBIM1-3 the assignment is more dubious because the fly and the human proteins cluster together. We conducted a functional analysis based on expression levels and the availability of RNAi lines. This revealed that the ubiquitous knockdown of CG3798/Nmda1 and CG3814/Lfg had no effect on development while knockdown of CG2076/dTmbim5 resulted in death at the pupa stage and knockdown of CG7188/dTmbim6 in death at the embryonic stage. Ubiquitous knockdown of the second TMBIM5 paralog CG1287/Mics1 ensued in male sterility. Knockdown of dTmbim5 and 6 in muscle and neural tissue also greatly reduced lifespan through different mechanisms. Knockdown of the mitochondrial family member dTmbim5 resulted in reduced ATP production and a pro-apoptotic expression profile while knockdown of the ER protein dTmbim6 increased the ER calcium levels similar to findings in mammalian cells. Our data demonstrate that dTmbim5 and 6 are essential for fly development and survival but affect cell survival through different mechanisms.
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Affiliation(s)
- Li Zhang
- University Medical Center, Institute for Molecular Medicine, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Sebastian Buhr
- University Medical Center, Institute for Molecular Medicine, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Aaron Voigt
- Department of Neurology, RWTH Aachen University, Aachen, Germany.,Forschungszentrum Jülich GmbH, JARA-Institute Molecular Neuroscience and Neuroimaging, RWTH Aachen University, Aachen, Germany
| | - Axel Methner
- University Medical Center, Institute for Molecular Medicine, Johannes Gutenberg University Mainz, Mainz, Germany
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5
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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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6
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Transmembrane BAX Inhibitor-1 Motif Containing Protein 5 (TMBIM5) Sustains Mitochondrial Structure, Shape, and Function by Impacting the Mitochondrial Protein Synthesis Machinery. Cells 2020; 9:cells9102147. [PMID: 32977469 PMCID: PMC7598220 DOI: 10.3390/cells9102147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 12/15/2022] Open
Abstract
The Transmembrane Bax Inhibitor-1 motif (TMBIM)-containing protein family is evolutionarily conserved and has been implicated in cell death susceptibility. The only member with a mitochondrial localization is TMBIM5 (also known as GHITM or MICS1), which affects cristae organization and associates with the Parkinson's disease-associated protein CHCHD2 in the inner mitochondrial membrane. We here used CRISPR-Cas9-mediated knockout HAP1 cells to shed further light on the function of TMBIM5 in physiology and cell death susceptibility. We found that compared to wild type, TMBIM5-knockout cells were smaller and had a slower proliferation rate. In these cells, mitochondria were more fragmented with a vacuolar cristae structure. In addition, the mitochondrial membrane potential was reduced and respiration was attenuated, leading to a reduced mitochondrial ATP generation. TMBIM5 did not associate with Mic10 and Mic60, which are proteins of the mitochondrial contact site and cristae organizing system (MICOS), nor did TMBIM5 knockout affect their expression levels. TMBIM5-knockout cells were more sensitive to apoptosis elicited by staurosporine and BH3 mimetic inhibitors of Bcl-2 and Bcl-XL. An unbiased proteomic comparison identified a dramatic downregulation of proteins involved in the mitochondrial protein synthesis machinery in TMBIM5-knockout cells. We conclude that TMBIM5 is important to maintain the mitochondrial structure and function possibly through the control of mitochondrial biogenesis.
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Philippaert K, Roden M, Lisak D, Bueno D, Jelenik T, Radyushkin K, Schacht T, Mesuere M, Wüllner V, Herrmann AK, Baumgart J, Vennekens R, Methner A. Bax inhibitor-1 deficiency leads to obesity by increasing Ca 2+-dependent insulin secretion. J Mol Med (Berl) 2020; 98:849-862. [PMID: 32394396 PMCID: PMC7297831 DOI: 10.1007/s00109-020-01914-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 04/14/2020] [Accepted: 04/21/2020] [Indexed: 12/28/2022]
Abstract
Abstract Transmembrane BAX inhibitor motif containing 6 (TMBIM6), also known as Bax inhibitor-1, is an evolutionarily conserved protein involved in endoplasmic reticulum (ER) function. TMBIM6 is an ER Ca2+ leak channel and its deficiency enhances susceptibility to ER stress due to inhibition of the ER stress sensor IRE1α. It was previously shown that TMBIM6 overexpression improves glucose metabolism and that TMBIM6 knockout mice develop obesity. We here examined the metabolic alterations underlying the obese phenotype and subjected TMBIM6 knockout mice to indirect calorimetry and euglycemic-hyperinsulinemic tests with stable isotope dilution to gauge tissue-specific insulin sensitivity. This demonstrated no changes in heat production, food intake, activity or hepatic and peripheral insulin sensitivity. TMBIM6 knockout mice, however, featured a higher glucose-stimulated insulin secretion in vivo as assessed by the hyperglycemic clamp test and hepatic steatosis. This coincided with profound changes in glucose-mediated Ca2+ regulation in isolated pancreatic β cells and increased levels of IRE1α levels but no differences in downstream effects of IRE1α like increased Xbp1 mRNA splicing or Ire1-dependent decay of insulin mRNA in the pancreas. We therefore conclude that lack of TMBIM6 does not affect insulin sensitivity but leads to hyperinsulinemia, which serves to explain the weight gain. TMBIM6-mediated metabolic alterations are mainly caused by its role as a Ca2+ release channel in the ER. Key messages TMBIM6−/− leads to obesity and hepatic steatosis. Food intake and energy expenditure are not changed in TMBIM6−/− mice. No changes in insulin resistance in TMBIM6−/− mice. Increased insulin secretion caused by altered calcium dynamics in β cells.
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Affiliation(s)
- Koenraad Philippaert
- Laboratory of Ion Channel Research, VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Michael Roden
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany. .,Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University, Düsseldorf, Germany. .,German Center for Diabetes Research (DZD), München-Neuherberg, Germany.
| | - Dmitrij Lisak
- Institute for Molecular Medicine of the University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Diones Bueno
- Institute for Molecular Medicine of the University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Tomas Jelenik
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University, Düsseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | | | - Teresa Schacht
- Institute for Molecular Medicine of the University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Margot Mesuere
- Laboratory of Ion Channel Research, VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Verena Wüllner
- Institute for Molecular Medicine of the University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Ann-Kathrin Herrmann
- Institute for Molecular Medicine of the University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Jan Baumgart
- Translational Animal Research Center, The Johannes Gutenberg University, Mainz, Germany
| | - Rudi Vennekens
- Laboratory of Ion Channel Research, VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Axel Methner
- Institute for Molecular Medicine of the University Medical Center, Johannes Gutenberg University, Mainz, Germany.
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8
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Godlewski M, Kobylińska A. Bax Inhibitor 1 (BI-1) as a conservative regulator of Programmed Cell Death. POSTEP HIG MED DOSW 2019. [DOI: 10.5604/01.3001.0013.6294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Programmed cell death (PCD) is a physiological process in which infected or unnecessary cells due to their suicidal death capability can be selectively eliminated. Pro- and antiapoptotic proteins play an important role in the induction or inhibition of this process. Presented article shows property of Bax-1 (BI-1) inhibitor which is one of the conservative protein associated with the endoplasmic reticulum (ER) as well as its cytoprotective role in the regulation of cellular processes. It was shown that: 1) BI-1 is a small protein consisting of 237 amino acids (human protein - 36 kDa) and has 6 (in animals) and 7 (in plants) α-helical transmembrane domains, 2) BI-1 is expressed in all organisms and in most tissues, moreover its level depends on the functional condition of cells and it is involved in the development or reaction to biotic and abiotic stresses, 3) BI-1 forms a pH-dependent Ca2+ channel enabling release of these ions from the ER, 4) cytoprotective effects of BI-1 requires a whole, unchanged C-terminus, 5) BI-1 can interact directly with numerous other proteins, BI-1 protein affects numerous cellular processes, including: counteracting ER stress, oxidative stress, loss of cellular Ca2+ homeostasis as well as this protein influences on sphingolipid metabolism, autophagy, actin polymerization, lysosomal activity and cell proliferation. Studies of BI-1 functions will allow understanding the mechanisms of anticancer therapy or increases the knowledge of crop tolerance to environmental stresses.
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Affiliation(s)
- Mirosław Godlewski
- Katedra Ekofizjologii Roślin, Instytut Biologii Eksperymentalnej, Wydział Biologii i Ochrony Środowiska, Uniwersytet Łódzki, Łódź
| | - Agnieszka Kobylińska
- Katedra Ekofizjologii Roślin, Instytut Biologii Eksperymentalnej, Wydział Biologii i Ochrony Środowiska, Uniwersytet Łódzki, Łódź
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9
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Xu G, Wang S, Han S, Xie K, Wang Y, Li J, Liu Y. Plant Bax Inhibitor-1 interacts with ATG6 to regulate autophagy and programmed cell death. Autophagy 2017; 13:1161-1175. [PMID: 28537463 PMCID: PMC5529081 DOI: 10.1080/15548627.2017.1320633] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Autophagy is an evolutionarily conserved catabolic process and is involved in the regulation of programmed cell death during the plant immune response. However, mechanisms regulating autophagy and cell death are incompletely understood. Here, we demonstrate that plant Bax inhibitor-1 (BI-1), a highly conserved cell death regulator, interacts with ATG6, a core autophagy-related protein. Silencing of BI-1 reduced the autophagic activity induced by both N gene-mediated resistance to Tobacco mosaic virus (TMV) and methyl viologen (MV), and enhanced N gene-mediated cell death. In contrast, overexpression of plant BI-1 increased autophagic activity and surprisingly caused autophagy-dependent cell death. These results suggest that plant BI-1 has both prosurvival and prodeath effects in different physiological contexts and both depend on autophagic activity.
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Affiliation(s)
- Guoyong Xu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China,Department of Biology, Duke University, Durham, NC, USA
| | - Shanshan Wang
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shaojie Han
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China,Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - Ke Xie
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China,School of Chemistry and Biological Engineering, University of Science and Technology, Beijing, China
| | - Yan Wang
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jinlin Li
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China,CONTACT Yule Liu School of Life Sciences, Tsinghua University, Beijing 100084, China
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10
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Bittremieux M, Gerasimenko JV, Schuermans M, Luyten T, Stapleton E, Alzayady KJ, De Smedt H, Yule DI, Mikoshiba K, Vangheluwe P, Gerasimenko OV, Parys JB, Bultynck G. DPB162-AE, an inhibitor of store-operated Ca 2+ entry, can deplete the endoplasmic reticulum Ca 2+ store. Cell Calcium 2017; 62:60-70. [PMID: 28196740 DOI: 10.1016/j.ceca.2017.01.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 01/27/2017] [Accepted: 01/27/2017] [Indexed: 02/05/2023]
Abstract
Store-operated Ca2+ entry (SOCE), an important Ca2+ signaling pathway in non-excitable cells, regulates a variety of cellular functions. To study its physiological role, pharmacological tools, like 2-aminoethyl diphenylborinate (2-APB), are used to impact SOCE. 2-APB is one of the best characterized SOCE inhibitors. However, 2-APB also activates SOCE at lower concentrations, while it inhibits inositol 1,4,5-trisphosphate receptors (IP3Rs), sarco/endoplasmic reticulum Ca2+-ATPases (SERCAs) and other ion channels, like TRP channels. Because of this, 2-APB analogues that inhibit SOCE more potently and more selectively compared to 2-APB have been developed. The recently developed DPB162-AE is such a structural diphenylborinate isomer of 2-APB that selectively inhibits SOCE currents by blocking the functional coupling between STIM1 and Orai1. However, we observed an adverse effect of DPB162-AE on the ER Ca2+-store content at concentrations required for complete SOCE inhibition. DPB162-AE increased the cytosolic Ca2+ levels by reducing the ER Ca2+ store in cell lines as well as in primary cells. DPB162-AE did not affect SERCA activity, but provoked a Ca2+ leak from the ER, even after application of the SERCA inhibitor thapsigargin. IP3Rs partly contributed to the DPB162-AE-induced Ca2+ leak, since pharmacologically and genetically inhibiting IP3R function reduced, but not completely blocked, the effects of DPB162-AE on the ER store content. Our results indicate that, in some conditions, the SOCE inhibitor DPB162-AE can reduce the ER Ca2+-store content by inducing a Ca2+-leak pathway at concentrations needed for adequate SOCE inhibition.
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Affiliation(s)
- Mart Bittremieux
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, 3000 Leuven, Belgium
| | - Julia V Gerasimenko
- Cardiff University, MCR Secretory Control Research Group, Cardiff School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, Wales, UK
| | - Marleen Schuermans
- KU Leuven, Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, 3000 Leuven, Belgium
| | - Tomas Luyten
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, 3000 Leuven, Belgium
| | - Eloise Stapleton
- Cardiff University, MCR Secretory Control Research Group, Cardiff School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, Wales, UK
| | - Kamil J Alzayady
- University of Rochester, Department of Pharmacology and Physiology, Rochester, NY 14642, USA
| | - Humbert De Smedt
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, 3000 Leuven, Belgium
| | - David I Yule
- University of Rochester, Department of Pharmacology and Physiology, Rochester, NY 14642, USA
| | - Katsuhiko Mikoshiba
- The Laboratory for Developmental Neurobiology, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Peter Vangheluwe
- KU Leuven, Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, 3000 Leuven, Belgium
| | - Oleg V Gerasimenko
- Cardiff University, MCR Secretory Control Research Group, Cardiff School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, Wales, UK
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, 3000 Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, 3000 Leuven, Belgium.
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11
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Liu Q. TMBIM-mediated Ca 2+ homeostasis and cell death. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:850-857. [PMID: 28064000 DOI: 10.1016/j.bbamcr.2016.12.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 11/25/2022]
Abstract
Ca2+ is a ubiquitous intracellular messenger that regulates numerous physiological activities in humans, animals, plants, and bacteria. Cytosolic Ca2+ is kept at a low level, but subcellular organelles such as the endoplasmic reticulum (ER) and Golgi apparatus maintain high-concentration Ca2+ stores. Under resting conditions, store Ca2+ homeostasis is dynamically regulated to equilibrate between active Ca2+ uptake and passive Ca2+ leak processes. The evolutionarily conserved Transmembrane BAX Inhibitor-1 Motif-containing (TMBIM) proteins mediate Ca2+ homeostasis and cell death. This review focuses on recent advances in functional and structural analysis of TMBIM proteins in regulation of the two related functions. The roles of TMBIM proteins in pathogen infection and cancer are also discussed with prospects for treatment. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Qun Liu
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
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12
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Lisak D, Schacht T, Gawlitza A, Albrecht P, Aktas O, Koop B, Gliem M, Hofstetter HH, Zanger K, Bultynck G, Parys JB, De Smedt H, Kindler T, Adams-Quack P, Hahn M, Waisman A, Reed JC, Hövelmeyer N, Methner A. BAX inhibitor-1 is a Ca(2+) channel critically important for immune cell function and survival. Cell Death Differ 2015; 23:358-68. [PMID: 26470731 DOI: 10.1038/cdd.2015.115] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 07/20/2015] [Accepted: 07/21/2015] [Indexed: 01/03/2023] Open
Abstract
The endoplasmic reticulum (ER) serves as the major intracellular Ca(2+) store and has a role in the synthesis and folding of proteins. BAX (BCL2-associated X protein) inhibitor-1 (BI-1) is a Ca(2+) leak channel also implicated in the response against protein misfolding, thereby connecting the Ca(2+) store and protein-folding functions of the ER. We found that BI-1-deficient mice suffer from leukopenia and erythrocytosis, have an increased number of splenic marginal zone B cells and higher abundance and nuclear translocation of NF-κB (nuclear factor-κ light-chain enhancer of activated B cells) proteins, correlating with increased cytosolic and ER Ca(2+) levels. When put into culture, purified knockout T cells and even more so B cells die spontaneously. This is preceded by increased activity of the mitochondrial initiator caspase-9 and correlated with a significant surge in mitochondrial Ca(2+) levels, suggesting an exhausted mitochondrial Ca(2+) buffer capacity as the underlying cause for cell death in vitro. In vivo, T-cell-dependent experimental autoimmune encephalomyelitis and B-cell-dependent antibody production are attenuated, corroborating the ex vivo results. These results suggest that BI-1 has a major role in the functioning of the adaptive immune system by regulating intracellular Ca(2+) homeostasis in lymphocytes.
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Affiliation(s)
- D Lisak
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn) and Department of Neurology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - T Schacht
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn) and Department of Neurology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - A Gawlitza
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn) and Department of Neurology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - P Albrecht
- Heinrich Heine Universität Düsseldorf, Department of Neurology, Düsseldorf, Germany
| | - O Aktas
- Heinrich Heine Universität Düsseldorf, Department of Neurology, Düsseldorf, Germany
| | - B Koop
- Heinrich Heine Universität Düsseldorf, Department of Neurology, Düsseldorf, Germany
| | - M Gliem
- Heinrich Heine Universität Düsseldorf, Department of Neurology, Düsseldorf, Germany
| | - H H Hofstetter
- Heinrich Heine Universität Düsseldorf, Department of Neurology, Düsseldorf, Germany
| | - K Zanger
- Center for Anatomy and Brain Research, Düsseldorf, Germany
| | - G Bultynck
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Belgium
| | - J B Parys
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Belgium
| | - H De Smedt
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Belgium
| | - T Kindler
- III Medical Clinic, University Medical Center of the Johannes Gutenberg-University of Mainz, Mainz, Germany
| | - P Adams-Quack
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University of Mainz, Mainz, Germany
| | - M Hahn
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University of Mainz, Mainz, Germany
| | - A Waisman
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University of Mainz, Mainz, Germany
| | - J C Reed
- Sanford Burnham Institute, La Jolla, CA, USA
| | - N Hövelmeyer
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University of Mainz, Mainz, Germany
| | - A Methner
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn) and Department of Neurology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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13
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Lisak DA, Schacht T, Enders V, Habicht J, Kiviluoto S, Schneider J, Henke N, Bultynck G, Methner A. The transmembrane Bax inhibitor motif (TMBIM) containing protein family: Tissue expression, intracellular localization and effects on the ER CA²⁺-filling state. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2104-14. [PMID: 25764978 DOI: 10.1016/j.bbamcr.2015.03.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 01/19/2015] [Accepted: 03/01/2015] [Indexed: 10/23/2022]
Abstract
Bax inhibitor-1 (BI-1) is an evolutionarily conserved pH-dependent Ca²⁺ leak channel in the endoplasmic reticulum and the founding member of a family of six highly hydrophobic mammalian proteins named transmembrane BAX inhibitor motif containing (TMBIM) 1-6 with BI-1 being TMBIM6. Here we compared the structure, subcellular localization, tissue expression and the effect on the cellular Ca²⁺ homeostasis of all family members side by side. We found that all TMBIM proteins possess the di-aspartyl pH sensor responsible for pH sensing identified in TMBIM6 and its bacterial homologue BsYetJ. TMBIM1-3 and TMBIM4-6 represent two phylogenetically distinct groups that are localized in the Golgi apparatus (TMBIM1-3), endoplasmic reticulum (TMBIM4-6) or mitochondria (TMBIM5) but share a common structure of at least seven transmembrane domains with the last domain being semi-hydrophobic. TMBIM1 is mainly expressed in muscle, TMBIM2 and 3 in the nervous system, TMBIM4 and 5 are ubiquitously expressed and TMBIM6 in skeletal muscle, kidney, liver and spleen. All TMBIM proteins reduce the Ca²⁺ content of the endoplasmic reticulum, and all but TMBIM5 also reduce the cytosolic resting Ca²⁺ concentration. These results suggest that the TMBIM family has comparable functions in the maintenance of intracellular Ca²⁺ homeostasis in a wide variety of tissues. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.
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Affiliation(s)
- Dmitrij A Lisak
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn(2)), Department of Neurology, Johannes Gutenberg University Medical Center Mainz, Langenbeckstr. 1, Mainz D-55131, Germany
| | - Teresa Schacht
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn(2)), Department of Neurology, Johannes Gutenberg University Medical Center Mainz, Langenbeckstr. 1, Mainz D-55131, Germany
| | - Vitalij Enders
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn(2)), Department of Neurology, Johannes Gutenberg University Medical Center Mainz, Langenbeckstr. 1, Mainz D-55131, Germany
| | - Jörn Habicht
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn(2)), Department of Neurology, Johannes Gutenberg University Medical Center Mainz, Langenbeckstr. 1, Mainz D-55131, Germany
| | - Santeri Kiviluoto
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-I bus 802, Herestraat 49, Leuven BE-3000, Belgium
| | - Julia Schneider
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn(2)), Department of Neurology, Johannes Gutenberg University Medical Center Mainz, Langenbeckstr. 1, Mainz D-55131, Germany
| | - Nadine Henke
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn(2)), Department of Neurology, Johannes Gutenberg University Medical Center Mainz, Langenbeckstr. 1, Mainz D-55131, Germany
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-I bus 802, Herestraat 49, Leuven BE-3000, Belgium
| | - Axel Methner
- Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn(2)), Department of Neurology, Johannes Gutenberg University Medical Center Mainz, Langenbeckstr. 1, Mainz D-55131, Germany.
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14
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Bultynck G, Kiviluoto S, Methner A. Bax Inhibitor-1 Is Likely a pH-Sensitive Calcium Leak Channel, Not a H+/Ca2+ Exchanger. Sci Signal 2014; 7:pe22. [DOI: 10.1126/scisignal.2005764] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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15
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Chang Y, Bruni R, Kloss B, Assur Z, Kloppmann E, Rost B, Hendrickson WA, Liu Q. Structural basis for a pH-sensitive calcium leak across membranes. Science 2014; 344:1131-5. [PMID: 24904158 DOI: 10.1126/science.1252043] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Calcium homeostasis balances passive calcium leak and active calcium uptake. Human Bax inhibitor-1 (hBI-1) is an antiapoptotic protein that mediates a calcium leak and is representative of a highly conserved and widely distributed family, the transmembrane Bax inhibitor motif (TMBIM) proteins. Here, we present crystal structures of a bacterial homolog and characterize its calcium leak activity. The structure has a seven-transmembrane-helix fold that features two triple-helix sandwiches wrapped around a central C-terminal helix. Structures obtained in closed and open conformations are reversibly interconvertible by change of pH. A hydrogen-bonded, pKa (where Ka is the acid dissociation constant)-perturbed pair of conserved aspartate residues explains the pH dependence of this transition, and biochemical studies show that pH regulates calcium influx in proteoliposomes. Homology models for hBI-1 provide insights into TMBIM-mediated calcium leak and cytoprotective activity.
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Affiliation(s)
- Yanqi Chang
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA
| | - Renato Bruni
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA
| | - Brian Kloss
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA
| | - Zahra Assur
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Edda Kloppmann
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA. Department of Bioinformatics and Computational Biology, Fakultät für Informatik, Technische Universität München, Garching, Germany
| | - Burkhard Rost
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA. Department of Bioinformatics and Computational Biology, Fakultät für Informatik, Technische Universität München, Garching, Germany
| | - Wayne A Hendrickson
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA. Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA. New York Structural Biology Center, National Synchrotron Light Source (NSLS) X4, Brookhaven National Laboratory, Upton, NY 11973, USA. Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Qun Liu
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA. New York Structural Biology Center, National Synchrotron Light Source (NSLS) X4, Brookhaven National Laboratory, Upton, NY 11973, USA.
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16
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TMBIM protein family: ancestral regulators of cell death. Oncogene 2014; 34:269-80. [DOI: 10.1038/onc.2014.6] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/27/2013] [Accepted: 01/02/2014] [Indexed: 12/13/2022]
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17
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Urra H, Dufey E, Lisbona F, Rojas-Rivera D, Hetz C. When ER stress reaches a dead end. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3507-3517. [PMID: 23988738 DOI: 10.1016/j.bbamcr.2013.07.024] [Citation(s) in RCA: 325] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/25/2013] [Accepted: 07/30/2013] [Indexed: 02/06/2023]
Abstract
Endoplasmic reticulum (ER) stress is a common feature of several physiological and pathological conditions affecting the function of the secretory pathway. To restore ER homeostasis, an orchestrated signaling pathway is engaged that is known as the unfolded protein response (UPR). The UPR has a primary function in stress adaptation and cell survival; however, under irreversible ER stress a switch to pro-apoptotic signaling events induces apoptosis of damaged cells. The mechanisms that initiate ER stress-dependent apoptosis are not fully understood. Several pathways have been described where we highlight the participation of the BCL-2 family of proteins and ER calcium release. In addition, recent findings also suggest that microRNAs and oxidative stress are relevant players on the transition from adaptive to cell death programs. Here we provide a global and integrated overview of the signaling networks that may determine the elimination of a cell under chronic ER stress. This article is part of a Special Section entitled: Cell Death Pathways.
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Affiliation(s)
- Hery Urra
- Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Estefanie Dufey
- Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Fernanda Lisbona
- Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Diego Rojas-Rivera
- Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Claudio Hetz
- Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA; Neurounion Biomedical Foundation, Santiago, Chile.
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18
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Monaco G, Vervliet T, Akl H, Bultynck G. The selective BH4-domain biology of Bcl-2-family members: IP3Rs and beyond. Cell Mol Life Sci 2013; 70:1171-83. [PMID: 22955373 PMCID: PMC11113329 DOI: 10.1007/s00018-012-1118-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 08/01/2012] [Accepted: 08/02/2012] [Indexed: 01/08/2023]
Abstract
Anti-apoptotic Bcl-2-family members not only neutralize pro-apoptotic proteins but also directly regulate intracellular Ca(2+) signaling from the endoplasmic reticulum (ER), critically controlling cellular health, survival, and death initiation. Furthermore, distinct Bcl-2-family members may selectively regulate inositol 1,4,5-trisphosphate receptor (IP3R): Bcl-2 likely acts as an endogenous inhibitor of the IP3R, preventing pro-apoptotic Ca(2+) transients, while Bcl-XL likely acts as an endogenous IP3R-sensitizing protein promoting pro-survival Ca(2+) oscillations. Furthermore, distinct functional domains in Bcl-2 and Bcl-XL may underlie the divergence in IP3R regulation. The Bcl-2 homology (BH) 4 domain, which targets the central modulatory domain of the IP3R, is likely to be Bcl-2's determining factor. In contrast, the hydrophobic cleft targets the C-terminal Ca(2+)-channel tail and might be more crucial for Bcl-XL's function. Furthermore, one amino acid critically different in the sequence of Bcl-2's and Bcl-XL's BH4 domains underpins their selective effect on Ca(2+) signaling and distinct biological properties of Bcl-2 versus Bcl-XL. This difference is evolutionary conserved across five classes of vertebrates and may represent a fundamental divergence in their biological function. Moreover, these insights open novel avenues to selectively suppress malignant Bcl-2 function in cancer cells by targeting its BH4 domain, while maintaining essential Bcl-XL functions in normal cells. Thus, IP3R-derived molecules that mimic the BH4 domain's binding site on the IP3R may function synergistically with BH3-mimetic molecules selectivity suppressing Bcl-2's proto-oncogenic activity. Finally, a more general role for the BH4 domain on IP3Rs, rather than solely anti-apoptotic, may not be excluded as part of a complex network of molecular interactions.
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MESH Headings
- Animals
- Calcium Signaling/genetics
- Calcium Signaling/physiology
- Humans
- Inositol 1,4,5-Trisphosphate Receptors/chemistry
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/physiology
- Models, Biological
- Multigene Family/genetics
- Multigene Family/physiology
- Protein Binding/genetics
- Protein Binding/physiology
- Protein Structure, Tertiary/genetics
- Protein Structure, Tertiary/physiology
- Proto-Oncogene Proteins c-bcl-2/chemistry
- Proto-Oncogene Proteins c-bcl-2/genetics
- Proto-Oncogene Proteins c-bcl-2/metabolism
- Proto-Oncogene Proteins c-bcl-2/physiology
- Substrate Specificity
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Affiliation(s)
- Giovanni Monaco
- Laboratory of Molecular and Cellular Signaling, Department Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-1 bus 802, 3000 Leuven, Belgium
| | - Tim Vervliet
- Laboratory of Molecular and Cellular Signaling, Department Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-1 bus 802, 3000 Leuven, Belgium
| | - Haidar Akl
- Laboratory of Molecular and Cellular Signaling, Department Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-1 bus 802, 3000 Leuven, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signaling, Department Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-1 bus 802, 3000 Leuven, Belgium
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Regulation of inositol 1,4,5-trisphosphate receptors during endoplasmic reticulum stress. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1612-24. [PMID: 23380704 DOI: 10.1016/j.bbamcr.2013.01.026] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Revised: 01/13/2013] [Accepted: 01/21/2013] [Indexed: 12/15/2022]
Abstract
The endoplasmic reticulum (ER) performs multiple functions in the cell: it is the major site of protein and lipid synthesis as well as the most important intracellular Ca(2+) reservoir. Adverse conditions, including a decrease in the ER Ca(2+) level or an increase in oxidative stress, impair the formation of new proteins, resulting in ER stress. The subsequent unfolded protein response (UPR) is a cellular attempt to lower the burden on the ER and to restore ER homeostasis by imposing a general arrest in protein synthesis, upregulating chaperone proteins and degrading misfolded proteins. This response can also lead to autophagy and, if the stress can not be alleviated, to apoptosis. The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) and IP3-induced Ca(2+) signaling are important players in these processes. Not only is the IP3R activity modulated in a dual way during ER stress, but also other key proteins involved in Ca(2+) signaling are modulated. Changes also occur at the structural level with a strengthening of the contacts between the ER and the mitochondria, which are important determinants of mitochondrial Ca(2+) uptake. The resulting cytoplasmic and mitochondrial Ca(2+) signals will control cellular decisions that either promote cell survival or cause their elimination via apoptosis. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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Kiviluoto S, Schneider L, Luyten T, Vervliet T, Missiaen L, De Smedt H, Parys JB, Methner A, Bultynck G. Bax inhibitor-1 is a novel IP₃ receptor-interacting and -sensitizing protein. Cell Death Dis 2012; 3:e367. [PMID: 22875004 PMCID: PMC3434651 DOI: 10.1038/cddis.2012.103] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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21
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Kim JH, Lee ER, Jeon K, Choi HY, Lim H, Kim SJ, Chae HJ, Park SH, Kim S, Seo YR, Kim JH, Cho SG. Role of BI-1 (TEGT)-mediated ERK1/2 activation in mitochondria-mediated apoptosis and splenomegaly in BI-1 transgenic mice. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:876-88. [DOI: 10.1016/j.bbamcr.2012.01.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 01/22/2012] [Accepted: 01/23/2012] [Indexed: 12/30/2022]
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22
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Kiviluoto S, Akl H, Vervliet T, Bultynck G, Parys JB, Missiaen L, De Smedt H. IP3 receptor-binding partners in cell-death mechanisms. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/wmts.5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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23
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Bultynck G, Kiviluoto S, Henke N, Ivanova H, Schneider L, Rybalchenko V, Luyten T, Nuyts K, De Borggraeve W, Bezprozvanny I, Parys JB, De Smedt H, Missiaen L, Methner A. The C terminus of Bax inhibitor-1 forms a Ca2+-permeable channel pore. J Biol Chem 2011; 287:2544-57. [PMID: 22128171 DOI: 10.1074/jbc.m111.275354] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Bax inhibitor-1 (BI-1) is a multitransmembrane domain-spanning endoplasmic reticulum (ER)-located protein that is evolutionarily conserved and protects against apoptosis and ER stress. Furthermore, BI-1 is proposed to modulate ER Ca(2+) homeostasis by acting as a Ca(2+)-leak channel. Based on experimental determination of the BI-1 topology, we propose that its C terminus forms a Ca(2+) pore responsible for its Ca(2+)-leak properties. We utilized a set of C-terminal peptides to screen for Ca(2+) leak activity in unidirectional (45)Ca(2+)-flux experiments and identified an α-helical 20-amino acid peptide causing Ca(2+) leak from the ER. The Ca(2+) leak was independent of endogenous ER Ca(2+)-release channels or other Ca(2+)-leak mechanisms, namely translocons and presenilins. The Ca(2+)-permeating property of the peptide was confirmed in lipid-bilayer experiments. Using mutant peptides, we identified critical residues responsible for the Ca(2+)-leak properties of this BI-1 peptide, including a series of critical negatively charged aspartate residues. Using peptides corresponding to the equivalent BI-1 domain from various organisms, we found that the Ca(2+)-leak properties were conserved among animal, but not plant and yeast orthologs. By mutating one of the critical aspartate residues in the proposed Ca(2+)-channel pore in full-length BI-1, we found that Asp-213 was essential for BI-1-dependent ER Ca(2+) leak. Thus, we elucidated residues critically important for BI-1-mediated Ca(2+) leak and its potential channel pore. Remarkably, one of these residues was not conserved among plant and yeast BI-1 orthologs, indicating that the ER Ca(2+)-leak properties of BI-1 are an added function during evolution.
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Affiliation(s)
- Geert Bultynck
- Department of Molecular Cell Biology, Laboratory of Molecular and Cellular Signaling, K.U. Leuven, B-3000 Leuven, Belgium.
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24
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Castillo K, Rojas-Rivera D, Lisbona F, Caballero B, Nassif M, Court FA, Schuck S, Ibar C, Walter P, Sierralta J, Glavic A, Hetz C. BAX inhibitor-1 regulates autophagy by controlling the IRE1α branch of the unfolded protein response. EMBO J 2011; 30:4465-78. [PMID: 21926971 DOI: 10.1038/emboj.2011.318] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 08/01/2011] [Indexed: 12/15/2022] Open
Abstract
Both autophagy and apoptosis are tightly regulated processes playing a central role in tissue homeostasis. Bax inhibitor 1 (BI-1) is a highly conserved protein with a dual role in apoptosis and endoplasmic reticulum (ER) stress signalling through the regulation of the ER stress sensor inositol requiring kinase 1 α (IRE1α). Here, we describe a novel function of BI-1 in the modulation of autophagy. BI-1-deficient cells presented a faster and stronger induction of autophagy, increasing LC3 flux and autophagosome formation. These effects were associated with enhanced cell survival under nutrient deprivation. Repression of autophagy by BI-1 was dependent on cJun-N terminal kinase (JNK) and IRE1α expression, possibly due to a displacement of TNF-receptor associated factor-2 (TRAF2) from IRE1α. Targeting BI-1 expression in flies altered autophagy fluxes and salivary gland degradation. BI-1 deficiency increased flies survival under fasting conditions. Increased expression of autophagy indicators was observed in the liver and kidney of bi-1-deficient mice. In summary, we identify a novel function of BI-1 in multicellular organisms, and suggest a critical role of BI-1 as a stress integrator that modulates autophagy levels and other interconnected homeostatic processes.
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Affiliation(s)
- Karen Castillo
- Center for Molecular Studies of the Cell, Department of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
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25
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Ca2+ signaling mechanisms of cell survival and cell death: An introduction. Cell Calcium 2011; 50:207-10. [DOI: 10.1016/j.ceca.2011.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 06/09/2011] [Indexed: 01/06/2023]
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26
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Li X, Qian J, Wang C, Zheng K, Ye L, Fu Y, Han N, Bian H, Pan J, Wang J, Zhu M. Regulating cytoplasmic calcium homeostasis can reduce aluminum toxicity in yeast. PLoS One 2011; 6:e21148. [PMID: 21698264 PMCID: PMC3115986 DOI: 10.1371/journal.pone.0021148] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 05/20/2011] [Indexed: 12/11/2022] Open
Abstract
Our previous study suggested that increased cytoplasmic calcium (Ca) signals may mediate aluminum (Al) toxicity in yeast (Saccharomyces cerevisiae). In this report, we found that a yeast mutant, pmc1, lacking the vacuolar calcium ion (Ca2+) pump Ca2+-ATPase (Pmc1p), was more sensitive to Al treatment than the wild-type strain. Overexpression of either PMC1 or an anti-apoptotic factor, such as Bcl-2, Ced-9 or PpBI-1, decreased cytoplasmic Ca2+ levels and rescued yeast from Al sensitivity in both the wild-type and pmc1 mutant. Moreover, pretreatment with the Ca2+ chelator BAPTA-AM sustained cytoplasmic Ca2+ at low levels in the presence of Al, effectively making the cells more tolerant to Al exposure. Quantitative RT-PCR revealed that the expression of calmodulin (CaM) and phospholipase C (PLC), which are in the Ca2+ signaling pathway, was down-regulated under Al stress. This effect was largely counteracted when cells overexpressed anti-apoptotic Ced-9 or were pretreated with BAPTA-AM. Taken together, our results suggest that the negative regulation of Al-induced cytoplasmic Ca signaling is a novel mechanism underlying internal resistance to Al toxicity.
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Affiliation(s)
- Xuan Li
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Jia Qian
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Chaoqun Wang
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Ke Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Lan Ye
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yu Fu
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Ning Han
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Hongwu Bian
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
- * E-mail: (MZ); (HB)
| | - Jianwei Pan
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, China
| | - Junhui Wang
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Muyuan Zhu
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
- * E-mail: (MZ); (HB)
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Henke N, Lisak DA, Schneider L, Habicht J, Pergande M, Methner A. The ancient cell death suppressor BAX inhibitor-1. Cell Calcium 2011; 50:251-60. [PMID: 21663964 DOI: 10.1016/j.ceca.2011.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 05/03/2011] [Accepted: 05/05/2011] [Indexed: 10/18/2022]
Abstract
Bax inhibitor-1 (BI-1) was initially identified for its ability to inhibit BAX-induced apoptosis in yeast cells and is the founding member of a family of highly hydrophobic proteins localized in diverse cellular membranes. It is evolutionarily conserved and orthologues from plants can substitute for mammalian BI-1 in regard to its anti-apoptotic function suggesting a high degree of functional conservation. BI-1 interacts with BCL-2 and BCL-XL and, similar to these two anti-apoptotic proteins, the effect of BI-1 on cell death involves changes in the amount of Ca(2+) releasable from intracellular stores. However, BI-1 is also a negative regulator of the endoplasmic reticulum stress sensor IRE1 α, it interacts with G-actin and increases actin polymerization, enhances cancer metastasis by altering glucose metabolism and activating the sodium-hydrogen exchanger, and reduces the production of reactive oxygen species through direct interaction with NADPH-P450 reductase. In this contribution, we summarize what is known about the expression, intracellular localization and structure of BI-1 and specifically illuminate its effects on the intracellular Ca(2+) homeostasis and how this might relate to its other functions. We also present a thorough phylogenetic analysis of BI-1 proteins from major phyla together with paralogues from all BI-1 family members.
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Affiliation(s)
- Nadine Henke
- Neurologische Klinik, Universitätsklinikum Düsseldorf, Moorenstr. 5, D-40225 Düsseldorf, Germany
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Integrating stress signals at the endoplasmic reticulum: The BCL-2 protein family rheostat. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:564-74. [DOI: 10.1016/j.bbamcr.2010.11.012] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 11/11/2010] [Accepted: 11/14/2010] [Indexed: 11/18/2022]
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29
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Krajewska M, Xu L, Xu W, Krajewski S, Kress CL, Cui J, Yang L, Irie F, Yamaguchi Y, Lipton SA, Reed JC. Endoplasmic reticulum protein BI-1 modulates unfolded protein response signaling and protects against stroke and traumatic brain injury. Brain Res 2011; 1370:227-37. [PMID: 21075086 PMCID: PMC3019258 DOI: 10.1016/j.brainres.2010.11.015] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 11/04/2010] [Accepted: 11/05/2010] [Indexed: 10/18/2022]
Abstract
Bax-Inhibitor-1 (BI-1) is an evolutionarily conserved cytoprotective protein that resides in membranes of the endoplasmic reticulum (ER). BI-1's cytoprotective activity is manifested in the context of ER stress, with previous studies showing that BI-1 modulates several ER-associated functions, including Unfolded Protein Response (UPR) signaling. Here we investigated the role of BI-1 in neuroprotection by generating transgenic mice in which BI-1 was constitutively expressed from a neuronal-specific promoter. Cultured primary cortical neurons from BI-1 transgenic mouse embryos exhibited greater resistance to cell death induced by agents known to cause ER stress compared to their non-transgenic counterparts. While brain morphology and vasculature of BI-1 mice appeared to be unchanged from normal non-transgenic mice, BI-1 transgenic mice showed reduced brain lesion volumes and better performance in motoric tests, compared with non-transgenic littermates, in two models of acute brain injury: stroke caused by middle cerebral artery occlusion (MCAO) and traumatic brain injury (TBI) caused by controlled cortical impact. Furthermore, brain tissue from BI-1 transgenic mice showed reduced levels of apoptotic cells and reduced induction of markers of ER stress after brain injury, including CHOP protein expression. In summary, our findings demonstrate that enforced neuronal expression of BI-1 reduces ER stress and provides protection from acute brain injury, suggesting that strategies for enhancing BI-1 expression or activity should be considered for development of new therapies for counteracting the consequences of stroke and acute brain trauma.
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Affiliation(s)
- Maryla Krajewska
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Lucy Xu
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Wenjie Xu
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Stan Krajewski
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | | | - Janice Cui
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Li Yang
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Fumitoshi Irie
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Yu Yamaguchi
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Stuart A. Lipton
- Sanford-Burnham Medical Research Institute, La Jolla, California
| | - John C. Reed
- Sanford-Burnham Medical Research Institute, La Jolla, California
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Cacas JL. Devil inside: does plant programmed cell death involve the endomembrane system? PLANT, CELL & ENVIRONMENT 2010; 33:1453-1473. [PMID: 20082668 DOI: 10.1111/j.1365-3040.2010.02117.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Eukaryotic cells have to constantly cope with environmental cues and integrate developmental signals. Cell survival or death is the only possible outcome. In the field of animal biology, tremendous efforts have been put into the understanding of mechanisms underlying cell fate decision. Distinct organelles have been proven to sense a broad range of stimuli and, if necessary, engage cell death signalling pathway(s). Over the years, forward and reverse genetic screens have uncovered numerous regulators of programmed cell death (PCD) in plants. However, to date, molecular networks are far from being deciphered and, apart from the autophagic compartment, no organelles have been assigned a clear role in the regulation of cellular suicide. The endomembrane system (ES) seems, nevertheless, to harbour a significant number of cell death mediators. In this review, the involvement of this system in the control of plant PCD is discussed in-depth, as well as compared and contrasted with what is known in animal and yeast systems.
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Affiliation(s)
- Jean-Luc Cacas
- Institut de Recherche pour le Développement, Equipe 2, Mécanismes des Résistances, Montpellier Cedex 5, France.
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31
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Intracellular Ca2+ storage in health and disease: a dynamic equilibrium. Cell Calcium 2010; 47:297-314. [PMID: 20189643 DOI: 10.1016/j.ceca.2010.02.001] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 01/31/2010] [Accepted: 02/01/2010] [Indexed: 12/17/2022]
Abstract
Homeostatic control of the endoplasmic reticulum (ER) both as the site for protein handling (synthesis, folding, trafficking, disaggregation and degradation) and as a Ca2+ store is of crucial importance for correct functioning of the cell. Disturbance of the homeostatic control mechanisms leads to a vast array of severe pathologies. The Ca2+ content of the ER is a dynamic equilibrium between active uptake via Ca2+ pumps and Ca2+ release by a number of highly regulated Ca2+-release channels. Regulation of the Ca2+-release channels is very complex and several mechanisms are still poorly understood or controversial. There is increasing evidence that a number of unrelated proteins, either by themselves or in association with other Ca2+ channels, can provide additional Ca2+-leak pathways. The ER is a dynamic organelle and changes in its size and components have been described, either as a result of (de)differentiation processes affecting the secretory capacity of cells, or as a result of adaptation mechanisms to diverse stress conditions such as the unfolded protein response and autophagy. In this review we want to give an overview of the current knowledge of the (short-term) regulatory mechanisms that affect Ca2+-release and Ca2+-leak pathways and of the (long-term) adaptations in ER size and capacity. Understanding of the consequences of these mechanisms for cellular Ca2+ signaling could provide a huge therapeutic potential.
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Rojas-Rivera D, Caballero B, Zamorano S, Lisbona F, Hetz C. Alternative Functions of the BCL-2 Protein Family at the Endoplasmic Reticulum. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 687:33-47. [DOI: 10.1007/978-1-4419-6706-0_2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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33
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Bax Inhibitor-1, a conserved cell death suppressor, is a key molecular switch downstream from a variety of biotic and abiotic stress signals in plants. Int J Mol Sci 2009; 10:3149-3167. [PMID: 19742129 PMCID: PMC2738916 DOI: 10.3390/ijms10073149] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/06/2009] [Accepted: 07/06/2009] [Indexed: 02/03/2023] Open
Abstract
In Nature plants are constantly challenged by a variety of environmental stresses that could lead to disruptions in cellular homeostasis. Programmed cell death (PCD) is a fundamental cellular process that is often associated with defense responses to pathogens, during development and in response to abiotic stresses in fungi, animals and plants. Although there are many characteristics shared between different types of PCD events, it remains unknown whether a common mechanism drives various types of PCD in eukaryotes. One candidate regulator for such a mechanism is Bax Inhibitor-1 (BI-1), an evolutionary conserved, endoplasmic reticulum (ER)-resident protein that represents an ancient cell death regulator that potentially regulates PCD in all eukaryotes. Recent findings strongly suggested that BI-1 plays an important role in the conserved ER stress response pathway to modulate cell death induction in response to multiple types of cell death signals. As ER stress signaling pathways has been suggested to play important roles not only in the control of ER homeostasis but also in other biological processes such as the response to pathogens and abiotic stress in plants, BI-1 might function to control the convergence point that modulates the level of the “pro-survival and pro-death” signals under multiple stress conditions.
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Szegezdi E, MacDonald DC, Ní Chonghaile T, Gupta S, Samali A. Bcl-2 family on guard at the ER. Am J Physiol Cell Physiol 2009; 296:C941-53. [DOI: 10.1152/ajpcell.00612.2008] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The endoplasmic reticulum (ER) is the main site for protein folding, lipid biosynthesis, and calcium storage in the cell. Disturbances of these critical cellular functions lead to ER stress. The ER responds to disturbances in its homeostasis by launching an adaptive signal transduction pathway, known as the unfolded protein response (UPR). The UPR strives to maintain ER function during stress; however, if the stress is not resolved, apoptotic responses are activated that involve cross talk between the ER and mitochondria. In addition, ER stress is also known to induce autophagy to counteract XBP-1-mediated ER expansion and assist in the degradation of unfolded proteins. One family of proteins involved in the regulation of apoptosis is that of B-cell lymphoma protein 2 (Bcl-2). Complex interactions among the three subgroups within the Bcl-2 family [the antiapoptotic, the multidomain proapoptotic, and the Bcl-2 homology domain 3 (BH3)-only members] control the signaling events of apoptosis upstream of mitochondrial outer membrane permeabilization. These proteins were found to have diverse subcellular locations to aid in the response to varied intrinsic and extrinsic stimuli. Of recent interest is the presence of the Bcl-2 family at the ER. Here, we review the involvement of proteins from each of the three Bcl-2 family subgroups in the maintenance of ER homeostasis and their participation in ER stress signal transduction pathways.
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Xu C, Xu W, Palmer AE, Reed JC. BI-1 regulates endoplasmic reticulum Ca2+ homeostasis downstream of Bcl-2 family proteins. J Biol Chem 2008; 283:11477-84. [PMID: 18299329 DOI: 10.1074/jbc.m708385200] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BI-1 (Bax inhibitor-1) is an evolutionarily conserved multitransmembrane protein that resides in the endoplasmic reticulum (ER) and that has documented cytoprotective functions in both animals and plants. Recent studies indicate that BI-1 shares in common with Bcl-2/Bax family proteins the ability to regulate the amounts of Ca(2+) that can be released from the ER by agents, such as the ER-Ca(2+)-ATPase (SERCA) inhibitor thapsigargin (TG). Using an ER-targeted, Ca(2+) indicator (cameleon), with characteristics optimized for measuring ER Ca(2+) ([Ca(2+)](er)), we studied the effects of BI-1 on [Ca(2+)](er) in resting and TG-treated cells. Similar to cells overexpressing antiapoptotic Bcl-2 or Bcl-X(L), overexpression of BI-1 resulted in lower resting [Ca(2+)](er), with concomitantly less Ca(2+) released into the cytosol upon stimulation by TG and with a higher rate of Ca(2+) leakage from the ER. Co-expression of SERCA restored levels of [Ca(2+)](er) to normal, showing opposing actions of the ER-Ca(2+)ATPase and BI-1 on ER Ca(2+) homeostasis. Conversely, cells with deficient BI-1 have increased [Ca(2+)](er), and release more Ca(2+) into the cytosol when challenged with TG. In BI-1-deficient cells, Bcl-X(L) fails to reduce [Ca(2+)](er), indicating that BI-1 functions downstream of Bcl-X(L). In bax(-/-)bak(-/-) double knock-out cells, both BI-1 and Bcl-X(L) retained their ability to reduce [Ca(2+)](er), suggesting that BI-1 and Bcl-X(L) operate downstream of or parallel to Bax/Bak. The findings reveal a hierarchy of functional interactions of BI-1 with Bcl-2/Bax family proteins in regulating ER Ca(2+) homeostasis.
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Affiliation(s)
- Chunyan Xu
- Program on Apoptosis and Cell Death Research, Burnham Institute for Medical Research, La Jolla, California 92037, USA
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36
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Hetz CA. ER stress signaling and the BCL-2 family of proteins: from adaptation to irreversible cellular damage. Antioxid Redox Signal 2007; 9:2345-55. [PMID: 17854276 DOI: 10.1089/ars.2007.1793] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Programmed cell death is essential for the development and maintenance of cellular homeostasis, and its deregulation results in a variety of pathologic conditions. The BCL-2 family of proteins is a group of evolutionarily conserved regulators of cell death that operate at the mitochondrial membrane to control caspase activation. This family is comprised both of antiapoptotic and proapoptotic members, in which a subset of proapoptotic members, called BH3-only proteins, acts as upstream activators of the core proapoptotic pathway. In addition to their known role at the mitochondria, different BCL-2-related proteins are located to the endoplasmic reticulum (ER) membrane, where new functions have been recently proposed. In this review, evidence is presented indicating that members of the BCL-2 protein family are contained in multiprotein complexes at the ER, regulating diverse cellular processes including autophagy, calcium homeostasis, the unfolded-protein response, ER membrane remodeling, and calcium-dependent cell death. Thus, BCL-2-related proteins are not only the "death gateway" keepers, but they also have alternative functions in essential cellular processes.
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Affiliation(s)
- Claudio A Hetz
- Department of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile and the FONDAP Center for Molecular Studies of the Cell (CEMC), Santiago, Chile.
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Watanabe N, Lam E. BAX inhibitor-1 modulates endoplasmic reticulum stress-mediated programmed cell death in Arabidopsis. J Biol Chem 2007; 283:3200-3210. [PMID: 18039663 DOI: 10.1074/jbc.m706659200] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The components and pathways that regulate programmed cell death (PCD) in plants remain poorly understood. Here we describe the impact of drug-induced endoplasmic reticulum (ER) stress on Arabidopsis seedlings and present evidence for the role of Arabidopsis BAX inhibitor-1 (AtBI1) as a modulator of ER stress-mediated PCD. We found that treatment of Arabidopsis seedlings with tunicamycin (TM), an inhibitor of N-linked glycosylation and an inducer of ER stress by triggering accumulation of unfolded proteins in the ER, results in strong inhibition of root growth and loss of survival accompanied by typical hallmarks of PCD such as accumulation of H(2)O(2), chromatin condensation, and oligonucleosomal fragmentation of nuclear DNA. These phenotypes are alleviated by co-treatment with either of two different chemical chaperones, sodium 4-phenylbutyrate and tauroursodeoxycholic acid, both with chaperone properties that can reduce the load of misfolded protein in the ER. Expression of AtBI1 mRNA and its promoter activity are increased dramatically prior to initiation of TM-induced PCD. Compared with wild-type plants, two AtBI1 mutants (atbi1-1 and atbi1-2) exhibit hypersensitivity to TM with accelerated PCD progression. Conversely, overexpressing AtBI1 markedly reduces the sensitivity of Arabidopsis seedlings to TM. However, alterations in AtBI1 gene expression levels do not cause a significant effect on the expression patterns of typical ER stress-inducible genes (AtBip2, AtPDI, AtCRT1, and AtCNX1). We propose that AtBI1 plays a pivotal role as a highly conserved survival factor during ER stress that acts in parallel to the unfolded protein response pathway.
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Affiliation(s)
- Naohide Watanabe
- Biotechnology Center for Agriculture and the Environment, Rutgers University, New Brunswick, New Jersey 08901-8550
| | - Eric Lam
- Biotechnology Center for Agriculture and the Environment, Rutgers University, New Brunswick, New Jersey 08901-8550.
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Manekeller S, Schuppius A, Stegemann J, Hirner A, Minor T. Role of perfusion medium, oxygen and rheology for endoplasmic reticulum stress-induced cell death after hypothermic machine preservation of the liver. Transpl Int 2007; 21:169-77. [PMID: 18005084 DOI: 10.1111/j.1432-2277.2007.00595.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Recently, the endoplasmic reticulum (ER) has been disclosed as subcellular target reactive to ischaemia/reperfusion and possibly influenced by hypothermic machine preservation. Here, the respective role of perfusate, perfusion itself, and the effect of continuous oxygenation to trigger ER-stress in the graft should be investigated. Livers were retrieved 30 min after cardiac arrest of male Wistar rats and preserved by cold storage (CS) in histidine-tryptophan-ketoglutarate (HTK) for 18 h at 4 degrees C. Other organs were subjected to aerobic conditions either by oxygenated machine perfusion with HTK (MP-HTK) or Belzer solution (MP-Belzer) at 4 degrees C or by venous insufflation of gaseous oxygen during cold storage (VSOP). Viability of livers was evaluated upon reperfusion in vitro according to previously validated techniques for 120 min at 37 degrees C. Oxygenation during preservation (MP-HTK, MP-Belzer or VSOP) concordantly improved functional recovery (bile flow, ammonia clearance), reduced parenchymal enzyme leakage and histological signs of necrosis and significantly attenuated mitochondrial induction of apoptosis (cleavage of caspase 9) compared to CS. However, MP with either medium produced about 500% elevated protein expression of CHOP/GADD153, suggesting pro-apoptotic ER-stress responses, paralleled by a significant elevation of caspase-12 enzyme activity compared to CS or VSOP. Although MP also promoted a slight (20%) induction of the cytoprotective ER-protein Bax inhibitor protein (BI-1), prevailing of proapoptotic reactions was seen by increased cleavage of caspase-3 and poly (ADP-Ribase)-polymerase (PARP) in both MP-groups. Endoplasmic stress activation is conjectured a specific side effect of long-term machine preservation irrespective of the medium, actually promoting cellular apoptosis via activation of caspase-12. The simple insufflation of gaseous O2 may be considered a feasible alternative, apparently indifferent to the endoplasmic reticulum.
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Oshima R, Yoshinaga K, Ihara-Ohori Y, Fukuda R, Ohta A, Uchimiya H, Kawai-Yamada M. The Bax lnhibitor-1 needs a functional electron transport chain for cell death suppression. FEBS Lett 2007; 581:4627-32. [PMID: 17825821 DOI: 10.1016/j.febslet.2007.08.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 08/13/2007] [Accepted: 08/27/2007] [Indexed: 12/27/2022]
Abstract
Bax inhibitor-1 (BI-1) is an evolutionarily conserved cell death suppresser in animals, yeast, and plants. In this study, yeast strains carrying single-gene deletions were screened for factors related to cell death suppression by Arabidopsis BI-1 (AtBI-1). Our screen identified mutants that failed to survive Bax-induced lethality even with AtBI-1 coexpression (Bax suppressor). The Deltacox16 strain was isolated as a BI-1-inactive mutant; it was disrupted in a component of the mitochondrial cytochrome c oxidase. Other mutants defective in mitochondrial electron transport showed a similar phenotype. ATP levels were markedly decreased in all these mutants, suggesting that BI-1 requires normal electron transport activity to suppress cell death in yeast.
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Affiliation(s)
- Reiko Oshima
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Bolduc N, Lamb GN, Cessna SG, Brisson LF. Modulation of Bax Inhibitor-1 and cytosolic Ca2+ by cytokinins in Nicotiana tabacum cells. Biochimie 2007; 89:961-71. [PMID: 17397988 DOI: 10.1016/j.biochi.2007.02.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 02/09/2007] [Indexed: 12/16/2022]
Abstract
The protein Bax Inhibitor-1 (BI-1) has recently emerged as a negative regulator of plant programmed cell death (PCD), but how it functions at the biochemical level remains unknown. To elucidate its regulation and mode of action, we used suspension cells of Nicotiana tabacum to study the effects of cytokinins (CKs) on the expression level of NtBI-1 via western analysis. We found that the NtBI-1 protein is up-regulated following treatments with CKs at concentrations inducing a stress response (determined by growth reduction and PR1a accumulation), but not at PCD-inducing concentrations. These data point toward a role for NtBI-1 in the stress response to CKs. Application of CKs was also accompanied by a rapid cytosolic Ca(2+) pulse, and inhibition of this pulse with La(3+) or EGTA partially restored viability, indicating a signaling role for Ca(2+) in CK-induced cell death. However, CK-induced NtBI-1 accumulation was not altered by pretreatment with La(3+), nor by treatment with several modulators of intracellular Ca(2+) homeostasis and signaling, suggesting that CK-dependent regulation of NtBI-1 accumulation is not directly mediated by Ca(2+).
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Affiliation(s)
- Nathalie Bolduc
- Département de Biochimie et de Microbiologie, Université Laval, Québec, QC G1K 7P4, Canada.
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Sahin M, Saxena A, Joost P, Lewerenz J, Methner A. Induction of Bcl-2 by functional regulation of G-protein coupled receptors protects from oxidative glutamate toxicity by increasing glutathione. Free Radic Res 2007; 40:1113-23. [PMID: 17050165 DOI: 10.1080/10715760600838191] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Glutamate treatment depletes hippocampal HT22 cells of glutathione, which renders the cells incapable to reduce reactive oxygen species and ultimately cumulates in cell death by oxidative stress. HT22 cells resistant to glutamate displayed increased phosphorylation of cAMP-response-element binding (CREB) and decreased ERK1/2 suggestive of differences in signal transmission. We investigated the amount of candidate G-protein-coupled receptors involved in this resistance and found an increase in mRNA for receptors activated by the vasoactive intestinal peptide VIP (VPAC2, 12.6-fold) and glutamate like the metabotropic glutamate receptor mGlu1 (5.3-fold). Treating cells with VIP and glutamate led to the same changes in protein phosphorylation observed in resistant cells and induced the proto-oncogene Bcl-2. Bcl-2 overexpression protected by increasing the amount of intracellular glutathione and Bcl-2 knockdown by small interfering RNAs (siRNA) increased glutamate susceptibility of resistant cells. Other receptors upregulated in this paradigm might represent useful targets in the treatment of neurological diseases associated with oxidative stress.
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Affiliation(s)
- Mert Sahin
- Department of Neurology, Heinrich Heine Universität Düsseldorf, Moorenstreet 5, 40225, Düsseldorf, Germany
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Eichmann R, Dechert C, Kogel KH, Hückelhoven R. Transient over-expression of barley BAX Inhibitor-1 weakens oxidative defence and MLA12-mediated resistance to Blumeria graminis f.sp. hordei. MOLECULAR PLANT PATHOLOGY 2006; 7:543-552. [PMID: 20507468 DOI: 10.1111/j.1364-3703.2006.00359.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
SUMMARY BAX Inhibitor-1 (BI-1) is a conserved cell death suppressor protein. In barley, BI-1 (HvBI-1) expression is induced upon powdery mildew infection and when over-expressed in epidermal cells of barley, HvBI-1 induces susceptibility to the biotrophic fungal pathogen Blumeria graminis. We co-expressed mammalian pro-apoptotic BAX together with HvBI-1, and the mammalian BAX antagonist BCL-X(L) in barley epidermal cells. BAX expression led to cessation of cytoplasmic streaming and collapse of the cytoplasm while co-expression of HvBI-1 and BCL-X(L) partially or completely, respectively, rescued cells from BAX lethality. When B. graminis was attacking epidermal cells, a green fluorescent protein fusion of HvBI-1 accumulated at the site of attempted penetration and was also present around haustoria. Over-expression of HvBI-1 in epidermal cells weakened a cell-wall-associated local hydrogen peroxide burst in a resistant mlo-mutant genotype and supported haustoria accommodation in race-specifically resistant MLA12-barley. HvBI-1 is a cell death regulator protein of barley with the potential to suppress host defence reactions.
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Affiliation(s)
- Ruth Eichmann
- Research Centre for BioSystems, Land Use and Nutrition, Institute of Phytopathology and Applied Zoology, Justus-Liebig-University Giessen, Heinrich-Buff Ring 26-32, D-35392 Giessen, Germany
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Imani J, Baltruschat H, Stein E, Jia G, Vogelsberg J, Kogel KH, Hückelhoven R. Expression of barley BAX Inhibitor-1 in carrots confers resistance to Botrytis cinerea. MOLECULAR PLANT PATHOLOGY 2006; 7:279-84. [PMID: 20507447 DOI: 10.1111/j.1364-3703.2006.00339.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
SUMMARY BAX Inhibitor-1 (BI-1) is a protein that controls heterologous BAX-induced cell death, the hypersensitive reaction and abiotic stress-induced cell death in plants. When over-expressed in epidermal cells of barley, barley BI-1 induces susceptibility to the biotrophic fungal pathogen Blumeria graminis. When we expressed barley BI-1 in carrot susceptible to the necrotrophic fungus Botrytis cinerea, we obtained BI-1-mediated resistance to fungus-induced leaf cell death and less fungal spreading on the leaves. Barley BI-1 also mediated resistance to Chalara elegans in carrot roots. The results support the idea that cell death inhibition is an applicable approach to control cell-death-inducing pathogens in crop plants.
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Affiliation(s)
- Jafargholi Imani
- Research Centre for BioSystems, Land Use and Nutrition, Institute of Phytopathology and Applied Zoology, Justus-Liebig-Universität Giessen, Heinrich-Buff Ring 26-32, D-35392 Giessen, Germany
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Nieuwenhuijs VB, De Bruijn MT, Padbury RTA, Barritt GJ. Hepatic ischemia-reperfusion injury: roles of Ca2+ and other intracellular mediators of impaired bile flow and hepatocyte damage. Dig Dis Sci 2006; 51:1087-102. [PMID: 16865576 DOI: 10.1007/s10620-006-8014-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 07/27/2005] [Indexed: 12/16/2022]
Abstract
Liver resection and liver transplantation have been successful in the treatment of liver tumors and end-stage liver disease. This success has led to an expansion in the pool of patients potentially treatable by liver surgery and, in the case of transplantation, to a shortage of liver donors. At present, there are significant numbers of potential candidates for liver resection and liver donation who have fatty livers, are aged, or have livers damaged by chemotherapy. All of these are at high risk for ischemic reperfusion (IR) injury. The aims of this review are to assess current knowledge of the clinical effectiveness of ischemic preconditioning and intermittent ischemia in reducing IR damage in liver surgery; to evaluate the use of bile flow as a sensitive indicator of IR liver damage; and to analyze the molecular mechanisms, especially intracellular Ca2+, involved in IR injury and ischemic preconditioning. It is concluded that bile flow is a sensitive indicator of IR injury. Together with reactive oxygen species (ROS) and other extracellular and intracellular signaling molecules, intracellular Ca2+ in hepatocytes plays a key role in the normal regulation of bile flow and in IR-induced injury and cell death. Ischemic preconditioning is an effective strategy to reduce IR injury but there is considerable scope for improvement, especially in patients with fatty and aged livers. The development of effective new strategies to reduce IR injury will depend on improved understanding of the molecular mechanisms involved, especially by gaining a better perspective of the relative importance of the various intrahepatocyte signaling pathways involved.
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Affiliation(s)
- Vincent B Nieuwenhuijs
- HPB and Liver Transplant Unit, Flinders Medical Centre and School of Medicine, Flinders University, Bedford Park, South Australia, 5042, Australia
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