1
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Raimi OG, Ojha H, Ehses K, Dederer V, Lange SM, Rivera CP, Deegan TD, Chen Y, Wightman M, Toth R, Labib KPM, Mathea S, Ranson N, Fernández-Busnadiego R, Muqit MMK. Mechanism of human PINK1 activation at the TOM complex in a reconstituted system. SCIENCE ADVANCES 2024; 10:eadn7191. [PMID: 38848361 PMCID: PMC11160474 DOI: 10.1126/sciadv.adn7191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Accepted: 05/02/2024] [Indexed: 06/09/2024]
Abstract
Loss-of-function mutations in PTEN-induced kinase 1 (PINK1) are a frequent cause of early-onset Parkinson's disease (PD). Stabilization of PINK1 at the translocase of outer membrane (TOM) complex of damaged mitochondria is critical for its activation. The mechanism of how PINK1 is activated in the TOM complex is unclear. Here, we report that co-expression of human PINK1 and all seven TOM subunits in Saccharomyces cerevisiae is sufficient for PINK1 activation. We use this reconstitution system to systematically assess the role of each TOM subunit toward PINK1 activation. We unambiguously demonstrate that the TOM20 and TOM70 receptor subunits are required for optimal PINK1 activation and map their sites of interaction with PINK1 using AlphaFold structural modeling and mutagenesis. We also demonstrate an essential role of the pore-containing subunit TOM40 and its structurally associated subunits TOM7 and TOM22 for PINK1 activation. These findings will aid in the development of small-molecule activators of PINK1 as a therapeutic strategy for PD.
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Affiliation(s)
- Olawale G. Raimi
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Hina Ojha
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Kenneth Ehses
- Institute of Neuropathology, University Medical Center Göttingen, 37099 Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Verena Dederer
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Institute of Pharmaceutical Chemistry, Goethe-Universität, 60438 Frankfurt, Germany
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences, Goethe-Universität, 60438 Frankfurt, Germany
| | - Sven M. Lange
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Cristian Polo Rivera
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Tom D. Deegan
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Yinchen Chen
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Melanie Wightman
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Rachel Toth
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Karim P. M. Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Sebastian Mathea
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Institute of Pharmaceutical Chemistry, Goethe-Universität, 60438 Frankfurt, Germany
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences, Goethe-Universität, 60438 Frankfurt, Germany
| | - Neil Ranson
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Rubén Fernández-Busnadiego
- Institute of Neuropathology, University Medical Center Göttingen, 37099 Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Faculty of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Miratul M. K. Muqit
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
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2
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den Brave F, Pfanner N, Becker T. Mitochondrial entry gate as regulatory hub. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119529. [PMID: 37951505 DOI: 10.1016/j.bbamcr.2023.119529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 06/18/2023] [Accepted: 06/23/2023] [Indexed: 11/14/2023]
Abstract
Mitochondria import 1000-1300 different precursor proteins from the cytosol. The main mitochondrial entry gate is formed by the translocase of the outer membrane (TOM complex). Molecular coupling and modification of TOM subunits control and modulate protein import in response to cellular signaling. The TOM complex functions as regulatory hub to integrate mitochondrial protein biogenesis and quality control into the cellular proteostasis network.
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Affiliation(s)
- Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany.
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3
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Ronayne CT, Latorre-Muro P. Navigating the landscape of mitochondrial-ER communication in health and disease. Front Mol Biosci 2024; 11:1356500. [PMID: 38323074 PMCID: PMC10844478 DOI: 10.3389/fmolb.2024.1356500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/10/2024] [Indexed: 02/08/2024] Open
Abstract
Intracellular organelle communication enables the maintenance of tissue homeostasis and health through synchronized adaptive processes triggered by environmental cues. Mitochondrial-Endoplasmic Reticulum (ER) communication sustains cellular fitness by adjusting protein synthesis and degradation, and metabolite and protein trafficking through organelle membranes. Mitochondrial-ER communication is bidirectional and requires that the ER-components of the Integrated Stress Response signal to mitochondria upon activation and, likewise, mitochondria signal to the ER under conditions of metabolite and protein overload to maintain proper functionality and ensure cellular survival. Declines in the mitochondrial-ER communication occur upon ageing and correlate with the onset of a myriad of heterogeneous age-related diseases such as obesity, type 2 diabetes, cancer, or neurodegenerative pathologies. Thus, the exploration of the molecular mechanisms of mitochondrial-ER signaling and regulation will provide insights into the most fundamental cellular adaptive processes with important therapeutical opportunities. In this review, we will discuss the pathways and mechanisms of mitochondrial-ER communication at the mitochondrial-ER interface and their implications in health and disease.
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Affiliation(s)
- Conor T. Ronayne
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Cell Biology, Harvard Medical School, Boston, MA, United States
| | - Pedro Latorre-Muro
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Cell Biology, Harvard Medical School, Boston, MA, United States
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4
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Cui M, Yamano K, Yamamoto K, Yamamoto-Imoto H, Minami S, Yamamoto T, Matsui S, Kaminishi T, Shima T, Ogura M, Tsuchiya M, Nishino K, Layden BT, Kato H, Ogawa H, Oki S, Okada Y, Isaka Y, Kosako H, Matsuda N, Yoshimori T, Nakamura S. HKDC1, a target of TFEB, is essential to maintain both mitochondrial and lysosomal homeostasis, preventing cellular senescence. Proc Natl Acad Sci U S A 2024; 121:e2306454120. [PMID: 38170752 PMCID: PMC10786298 DOI: 10.1073/pnas.2306454120] [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: 04/23/2023] [Accepted: 11/15/2023] [Indexed: 01/05/2024] Open
Abstract
Mitochondrial and lysosomal functions are intimately linked and are critical for cellular homeostasis, as evidenced by the fact that cellular senescence, aging, and multiple prominent diseases are associated with concomitant dysfunction of both organelles. However, it is not well understood how the two important organelles are regulated. Transcription factor EB (TFEB) is the master regulator of lysosomal function and is also implicated in regulating mitochondrial function; however, the mechanism underlying the maintenance of both organelles remains to be fully elucidated. Here, by comprehensive transcriptome analysis and subsequent chromatin immunoprecipitation-qPCR, we identified hexokinase domain containing 1 (HKDC1), which is known to function in the glycolysis pathway as a direct TFEB target. Moreover, HKDC1 was upregulated in both mitochondrial and lysosomal stress in a TFEB-dependent manner, and its function was critical for the maintenance of both organelles under stress conditions. Mechanistically, the TFEB-HKDC1 axis was essential for PINK1 (PTEN-induced kinase 1)/Parkin-dependent mitophagy via its initial step, PINK1 stabilization. In addition, the functions of HKDC1 and voltage-dependent anion channels, with which HKDC1 interacts, were essential for the clearance of damaged lysosomes and maintaining mitochondria-lysosome contact. Interestingly, HKDC1 regulated mitophagy and lysosomal repair independently of its prospective function in glycolysis. Furthermore, loss function of HKDC1 accelerated DNA damage-induced cellular senescence with the accumulation of hyperfused mitochondria and damaged lysosomes. Our results show that HKDC1, a factor downstream of TFEB, maintains both mitochondrial and lysosomal homeostasis, which is critical to prevent cellular senescence.
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Affiliation(s)
- Mengying Cui
- Department of Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
| | - Koji Yamano
- Ubiquitin Project, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo156-8506, Japan
- Department of Biomolecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo113-8510, Japan
| | - Kenichi Yamamoto
- Department of Statistical Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
| | - Hitomi Yamamoto-Imoto
- Department of Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
| | - Satoshi Minami
- Department of Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
- Department of Nephrology, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
| | - Takeshi Yamamoto
- Department of Nephrology, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
| | - Sho Matsui
- Department of Nephrology, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
| | - Tatsuya Kaminishi
- Department of Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
- Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Suita, Osaka565-0871, Japan
| | - Takayuki Shima
- Department of Biochemistry, Nara Medical University, Kashihara, Nara634-8521, Japan
| | - Monami Ogura
- Department of Intracellular Membrane Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka565-0871, Japan
| | - Megumi Tsuchiya
- Laboratory of Nuclear Dynamics Group, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka565-0871, Japan
| | - Kohei Nishino
- Division of Cell Signaling, Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima770-8503, Japan
| | - Brian T. Layden
- Division of Endocrinology, Diabetes, and Metabolism, University of Illinois Chicago, Chicago, IL60612
- Jesse Brown Veterans Affairs Medical Center, Chicago, IL60612
| | - Hisakazu Kato
- Department of Medical Biochemistry, Graduate School of Medicine/Frontier Bioscience, Osaka University, Suita, Osaka565-0871, Japan
| | - Hidesato Ogawa
- Laboratory of Nuclear Dynamics Group, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka565-0871, Japan
| | - Shinya Oki
- Department of Drug Discovery Medicine, Graduate School of Medicine, Kyoto University, Kyoto606-8501, Japan
| | - Yukinori Okada
- Department of Statistical Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
- Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Suita, Osaka565-0871, Japan
- Laboratory of Statistical Immunology, Immunology Frontier Research Center, World Premier International Research Center (WPI-IFReC), Osaka University, Suita, Osaka565-0871, Japan
| | - Yoshitaka Isaka
- Department of Nephrology, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
| | - Hidetaka Kosako
- Division of Cell Signaling, Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima770-8503, Japan
| | - Noriyuki Matsuda
- Ubiquitin Project, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo156-8506, Japan
- Department of Biomolecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo113-8510, Japan
| | - Tamotsu Yoshimori
- Department of Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka565-0871, Japan
- Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Suita, Osaka565-0871, Japan
- Department of Intracellular Membrane Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka565-0871, Japan
| | - Shuhei Nakamura
- Department of Biochemistry, Nara Medical University, Kashihara, Nara634-8521, Japan
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5
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Ornelas P, Bausewein T, Martin J, Morgner N, Nussberger S, Kühlbrandt W. Two conformations of the Tom20 preprotein receptor in the TOM holo complex. Proc Natl Acad Sci U S A 2023; 120:e2301447120. [PMID: 37579144 PMCID: PMC10450662 DOI: 10.1073/pnas.2301447120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 07/17/2023] [Indexed: 08/16/2023] Open
Abstract
The TOM complex is the main entry point for precursor proteins (preproteins) into mitochondria. Preproteins containing targeting sequences are recognized by the TOM complex and imported into mitochondria. We have determined the structure of the TOM core complex from Neurospora crassa by single-particle electron cryomicroscopy at 3.3 Å resolution, showing its interaction with a bound preprotein at 4 Å resolution, and of the TOM holo complex including the Tom20 receptor at 6 to 7 Å resolution. TOM is a transmembrane complex consisting of two β-barrels, three receptor subunits, and three short transmembrane subunits. Tom20 has a transmembrane helix and a receptor domain on the cytoplasmic side. We propose that Tom20 acts as a dynamic gatekeeper, guiding preproteins into the pores of the TOM complex. We analyze the interactions of Tom20 with other TOM subunits, present insights into the structure of the TOM holo complex, and suggest a translocation mechanism.
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Affiliation(s)
- Pamela Ornelas
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt60438, Germany
| | - Thomas Bausewein
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt60438, Germany
| | - Janosch Martin
- Department of Structural Biology, Institute of Physical and Theoretical Chemistry, Goethe University of Frankfurt, Frankfurt60439, Germany
| | - Nina Morgner
- Department of Structural Biology, Institute of Physical and Theoretical Chemistry, Goethe University of Frankfurt, Frankfurt60439, Germany
| | - Stephan Nussberger
- Department of Biophysics, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Stuttgart70569, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt60438, Germany
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6
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Bennett CF, Latorre-Muro P, Puigserver P. Mechanisms of mitochondrial respiratory adaptation. Nat Rev Mol Cell Biol 2022; 23:817-835. [PMID: 35804199 PMCID: PMC9926497 DOI: 10.1038/s41580-022-00506-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2022] [Indexed: 02/07/2023]
Abstract
Mitochondrial energetic adaptations encompass a plethora of conserved processes that maintain cell and organismal fitness and survival in the changing environment by adjusting the respiratory capacity of mitochondria. These mitochondrial responses are governed by general principles of regulatory biology exemplified by changes in gene expression, protein translation, protein complex formation, transmembrane transport, enzymatic activities and metabolite levels. These changes can promote mitochondrial biogenesis and membrane dynamics that in turn support mitochondrial respiration. The main regulatory components of mitochondrial energetic adaptation include: the transcription coactivator peroxisome proliferator-activated receptor-γ (PPARγ) coactivator 1α (PGC1α) and associated transcription factors; mTOR and endoplasmic reticulum stress signalling; TOM70-dependent mitochondrial protein import; the cristae remodelling factors, including mitochondrial contact site and cristae organizing system (MICOS) and OPA1; lipid remodelling; and the assembly and metabolite-dependent regulation of respiratory complexes. These adaptive molecular and structural mechanisms increase respiration to maintain basic processes specific to cell types and tissues. Failure to execute these regulatory responses causes cell damage and inflammation or senescence, compromising cell survival and the ability to adapt to energetically demanding conditions. Thus, mitochondrial adaptive cellular processes are important for physiological responses, including to nutrient availability, temperature and physical activity, and their failure leads to diseases associated with mitochondrial dysfunction such as metabolic and age-associated diseases and cancer.
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Affiliation(s)
- Christopher F Bennett
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Pedro Latorre-Muro
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Pere Puigserver
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.
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7
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Drwesh L, Heim B, Graf M, Kehr L, Hansen-Palmus L, Franz-Wachtel M, Macek B, Kalbacher H, Buchner J, Rapaport D. A network of cytosolic (co)chaperones promotes the biogenesis of mitochondrial signal-anchored outer membrane proteins. eLife 2022; 11:77706. [PMID: 35876647 PMCID: PMC9355564 DOI: 10.7554/elife.77706] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 07/25/2022] [Indexed: 11/21/2022] Open
Abstract
Signal-anchored (SA) proteins are anchored into the mitochondrial outer membrane (OM) via a single transmembrane segment at their N-terminus while the bulk of the proteins is facing the cytosol. These proteins are encoded by nuclear DNA, translated on cytosolic ribosomes, and are then targeted to the organelle and inserted into its OM by import factors. Recently, research on the insertion mechanisms of these proteins into the mitochondrial OM have gained a lot of attention. In contrast, the early cytosolic steps of their biogenesis are unresolved. Using various proteins from this category and a broad set of in vivo, in organello, and in vitro assays, we reconstituted the early steps of their biogenesis. We identified a subset of molecular (co)chaperones that interact with newly synthesized SA proteins, namely, Hsp70 and Hsp90 chaperones and co-chaperones from the Hsp40 family like Ydj1 and Sis1. These interactions were mediated by the hydrophobic transmembrane segments of the SA proteins. We further demonstrate that interfering with these interactions inhibits the biogenesis of SA proteins to a various extent. Finally, we could demonstrate direct interaction of peptides corresponding to the transmembrane segments of SA proteins with the (co)chaperones and reconstitute in vitro the transfer of such peptides from the Hsp70 chaperone to the mitochondrial Tom70 receptor. Collectively, this study unravels an array of cytosolic chaperones and mitochondrial import factors that facilitates the targeting and membrane integration of mitochondrial SA proteins.
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Affiliation(s)
- Layla Drwesh
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Benjamin Heim
- Department of Chemistry, Technische Universität München, Munich, Germany
| | - Max Graf
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Linda Kehr
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Lea Hansen-Palmus
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Mirita Franz-Wachtel
- Proteome Center Tübingen, Interfaculty Institute for Cell Biology,, University of Tübingen, Tübingen, Germany
| | - Boris Macek
- Proteome Center Tübingen, Interfaculty Institute for Cell Biology,, University of Tübingen, Tübingen, Germany
| | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Johannes Buchner
- Department of Chemistry, Technische Universität München, Garching, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
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8
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Sayyed UMH, Mahalakshmi R. Mitochondrial protein translocation machinery: From TOM structural biogenesis to functional regulation. J Biol Chem 2022; 298:101870. [PMID: 35346689 PMCID: PMC9052162 DOI: 10.1016/j.jbc.2022.101870] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 03/13/2022] [Accepted: 03/14/2022] [Indexed: 01/15/2023] Open
Abstract
The human mitochondrial outer membrane is biophysically unique as it is the only membrane possessing transmembrane β-barrel proteins (mitochondrial outer membrane proteins, mOMPs) in the cell. The most vital of the three mOMPs is the core protein of the translocase of the outer mitochondrial membrane (TOM) complex. Identified first as MOM38 in Neurospora in 1990, the structure of Tom40, the core 19-stranded β-barrel translocation channel, was solved in 2017, after nearly three decades. Remarkably, the past four years have witnessed an exponential increase in structural and functional studies of yeast and human TOM complexes. In addition to being conserved across all eukaryotes, the TOM complex is the sole ATP-independent import machinery for nearly all of the ∼1000 to 1500 known mitochondrial proteins. Recent cryo-EM structures have provided detailed insight into both possible assembly mechanisms of the TOM core complex and organizational dynamics of the import machinery and now reveal novel regulatory interplay with other mOMPs. Functional characterization of the TOM complex using biochemical and structural approaches has also revealed mechanisms for substrate recognition and at least five defined import pathways for precursor proteins. In this review, we discuss the discovery, recently solved structures, molecular function, and regulation of the TOM complex and its constituents, along with the implications these advances have for alleviating human diseases.
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Affiliation(s)
- Ulfat Mohd Hanif Sayyed
- Molecular Biophysics Laboratory, Indian Institute of Science Education and Research, Bhopal, India
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9
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Walter C, Marada A, Suhm T, Ernsberger R, Muders V, Kücükköse C, Sánchez-Martín P, Hu Z, Aich A, Loroch S, Solari FA, Poveda-Huertes D, Schwierzok A, Pommerening H, Matic S, Brix J, Sickmann A, Kraft C, Dengjel J, Dennerlein S, Brummer T, Vögtle FN, Meisinger C. Global kinome profiling reveals DYRK1A as critical activator of the human mitochondrial import machinery. Nat Commun 2021; 12:4284. [PMID: 34257281 PMCID: PMC8277783 DOI: 10.1038/s41467-021-24426-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 06/15/2021] [Indexed: 11/21/2022] Open
Abstract
The translocase of the outer mitochondrial membrane TOM constitutes the organellar entry gate for nearly all precursor proteins synthesized on cytosolic ribosomes. Thus, TOM presents the ideal target to adjust the mitochondrial proteome upon changing cellular demands. Here, we identify that the import receptor TOM70 is targeted by the kinase DYRK1A and that this modification plays a critical role in the activation of the carrier import pathway. Phosphorylation of TOM70Ser91 by DYRK1A stimulates interaction of TOM70 with the core TOM translocase. This enables transfer of receptor-bound precursors to the translocation pore and initiates their import. Consequently, loss of TOM70Ser91 phosphorylation results in a strong decrease in import capacity of metabolite carriers. Inhibition of DYRK1A impairs mitochondrial structure and function and elicits a protective transcriptional response to maintain a functional import machinery. The DYRK1A-TOM70 axis will enable insights into disease mechanisms caused by dysfunctional DYRK1A, including autism spectrum disorder, microcephaly and Down syndrome.
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Affiliation(s)
- Corvin Walter
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Adinarayana Marada
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Tamara Suhm
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ralf Ernsberger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Vera Muders
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Cansu Kücükköse
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Pablo Sánchez-Martín
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Zehan Hu
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Abhishek Aich
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Stefan Loroch
- Leibniz Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund, Germany
| | | | - Daniel Poveda-Huertes
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Alexandra Schwierzok
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Henrike Pommerening
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Stanka Matic
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jan Brix
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Albert Sickmann
- Leibniz Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund, Germany
| | - Claudine Kraft
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Jörn Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Sven Dennerlein
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Tilman Brummer
- Institute of Molecular Medicine, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
- German Cancer Consortium DKTK Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - F-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
- CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany.
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany.
| | - Chris Meisinger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
- CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany.
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.
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10
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Latorre-Muro P, O'Malley KE, Bennett CF, Perry EA, Balsa E, Tavares CDJ, Jedrychowski M, Gygi SP, Puigserver P. A cold-stress-inducible PERK/OGT axis controls TOM70-assisted mitochondrial protein import and cristae formation. Cell Metab 2021; 33:598-614.e7. [PMID: 33592173 PMCID: PMC7962155 DOI: 10.1016/j.cmet.2021.01.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 11/20/2020] [Accepted: 01/13/2021] [Indexed: 12/14/2022]
Abstract
The architecture of cristae provides a spatial mitochondrial organization that contains functional respiratory complexes. Several protein components including OPA1 and MICOS complex subunits organize cristae structure, but upstream regulatory mechanisms are largely unknown. Here, in vivo and in vitro reconstitution experiments show that the endoplasmic reticulum (ER) kinase PERK promotes cristae formation by increasing TOM70-assisted mitochondrial import of MIC19, a critical subunit of the MICOS complex. Cold stress or β-adrenergic stimulation activates PERK that phosphorylates O-linked N-acetylglucosamine transferase (OGT). Phosphorylated OGT glycosylates TOM70 on Ser94, enhancing MIC19 protein import into mitochondria and promoting cristae formation and respiration. In addition, PERK-activated OGT O-GlcNAcylates and attenuates CK2α activity, which mediates TOM70 Ser94 phosphorylation and decreases MIC19 mitochondrial protein import. We have identified a cold-stress inter-organelle PERK-OGT-TOM70 axis that increases cell respiration through mitochondrial protein import and subsequent cristae formation. These studies have significant implications in cellular bioenergetics and adaptations to stress conditions.
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Affiliation(s)
- Pedro Latorre-Muro
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Katherine E O'Malley
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Christopher F Bennett
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Elizabeth A Perry
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Eduardo Balsa
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Clint D J Tavares
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Mark Jedrychowski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Pere Puigserver
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA.
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11
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Palmer CS, Anderson AJ, Stojanovski D. Mitochondrial protein import dysfunction: mitochondrial disease, neurodegenerative disease and cancer. FEBS Lett 2021; 595:1107-1131. [PMID: 33314127 DOI: 10.1002/1873-3468.14022] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/12/2020] [Accepted: 10/17/2020] [Indexed: 12/13/2022]
Abstract
The majority of proteins localised to mitochondria are encoded by the nuclear genome, with approximately 1500 proteins imported into mammalian mitochondria. Dysfunction in this fundamental cellular process is linked to a variety of pathologies including neuropathies, cardiovascular disorders, myopathies, neurodegenerative diseases and cancer, demonstrating the importance of mitochondrial protein import machinery for cellular function. Correct import of proteins into mitochondria requires the co-ordinated activity of multimeric protein translocation and sorting machineries located in both the outer and inner mitochondrial membranes, directing the imported proteins to the destined mitochondrial compartment. This dynamic process maintains cellular homeostasis, and its dysregulation significantly affects cellular signalling pathways and metabolism. This review summarises current knowledge of the mammalian mitochondrial import machinery and the pathological consequences of mutation of its components. In addition, we will discuss the role of mitochondrial import in cancer, and our current understanding of the role of mitochondrial import in neurodegenerative diseases including Alzheimer's disease, Huntington's disease and Parkinson's disease.
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Affiliation(s)
- Catherine S Palmer
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Australia
| | - Alexander J Anderson
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Australia
| | - Diana Stojanovski
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Australia
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12
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Kreimendahl S, Rassow J. The Mitochondrial Outer Membrane Protein Tom70-Mediator in Protein Traffic, Membrane Contact Sites and Innate Immunity. Int J Mol Sci 2020; 21:E7262. [PMID: 33019591 PMCID: PMC7583919 DOI: 10.3390/ijms21197262] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 02/08/2023] Open
Abstract
Tom70 is a versatile adaptor protein of 70 kDa anchored in the outer membrane of mitochondria in metazoa, fungi and amoeba. The tertiary structure was resolved for the Tom70 of yeast, showing 26 α-helices, most of them participating in the formation of 11 tetratricopeptide repeat (TPR) motifs. Tom70 serves as a docking site for cytosolic chaperone proteins and co-chaperones and is thereby involved in the uptake of newly synthesized chaperone-bound proteins in mitochondrial biogenesis. In yeast, Tom70 additionally mediates ER-mitochondria contacts via binding to sterol transporter Lam6/Ltc1. In mammalian cells, TOM70 promotes endoplasmic reticulum (ER) to mitochondria Ca2+ transfer by association with the inositol-1,4,5-triphosphate receptor type 3 (IP3R3). TOM70 is specifically targeted by the Bcl-2-related protein MCL-1 that acts as an anti-apoptotic protein in macrophages infected by intracellular pathogens, but also in many cancer cells. By participating in the recruitment of PINK1 and the E3 ubiquitin ligase Parkin, TOM70 can be implicated in the development of Parkinson's disease. TOM70 acts as receptor of the mitochondrial antiviral-signaling protein (MAVS) and thereby participates in the corresponding system of innate immunity against viral infections. The protein encoded by Orf9b in the genome of SARS-CoV-2 binds to TOM70, probably compromising the synthesis of type I interferons.
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Affiliation(s)
| | - Joachim Rassow
- Institute for Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44801 Bochum, Germany;
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13
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Cytosolic Events in the Biogenesis of Mitochondrial Proteins. Trends Biochem Sci 2020; 45:650-667. [DOI: 10.1016/j.tibs.2020.04.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 03/18/2020] [Accepted: 04/02/2020] [Indexed: 01/08/2023]
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14
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Tom70 protects against diabetic cardiomyopathy through its antioxidant and antiapoptotic properties. Hypertens Res 2020; 43:1047-1056. [PMID: 32724135 DOI: 10.1038/s41440-020-0518-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 03/05/2020] [Accepted: 03/16/2020] [Indexed: 01/18/2023]
Abstract
Mitochondrial dysfunction plays a critical role in the pathogenesis of diabetic cardiomyopathy. Translocase of mitochondrial outer membrane 70 (Tom70) primarily facilitates the import of mitochondrial preproteins that may be involved in the regulation of oxidative stress and mitochondrial function. This study aimed to investigate the role of Tom70 in the development of myocardial injury in leptin receptor-deficient (db/db) diabetic mice. Tom70 siRNA or an overexpressing lentivirus was intramuscularly injected into mouse hearts or used to treat cultured neonatal cardiomyocytes. We found that Tom70 was downregulated in the diabetic hearts compared with the level in the wild-type hearts and that knocking down Tom70 exacerbated cardiac hypertrophy, fibrosis, and ventricular dysfunction in the db/db mice. Similarly, the in vitro data demonstrated that silencing Tom70 enhanced high-glucose and high-fat (HGHF) medium treatment-induced mitochondrial superoxide production, decreased ATP production and the mitochondrial membrane potential, and enhanced cell apoptosis in neonatal cardiomyocytes. Importantly, overexpression of Tom70 alleviated HGHF medium-induced oxidative stress, mitochondrial dysfunction, and cell apoptosis. Furthermore, in vivo data confirmed that reconstitution of Tom70 ameliorated cardiac hypertrophy, interstitial fibrosis, and ventricular dysfunction in the db/db mice. In addition, Tom70 overexpression mitigated mitochondrial fragmentation and dysfunction in the hearts of the db/db mice. Taken together, these findings suggest that downregulation of Tom70 contributes to the development of diabetic cardiomyopathy and that reconstitution of Tom70 may be a new therapeutic strategy for the prevention and treatment of diabetic cardiomyopathy.
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15
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Abstract
Mitochondria are essential organelles of eukaryotic cells. They consist of hundreds of different proteins that exhibit crucial activities in respiration, catabolic metabolism and the synthesis of amino acids, lipids, heme and iron-sulfur clusters. With the exception of a handful of hydrophobic mitochondrially encoded membrane proteins, all these proteins are synthesized on cytosolic ribosomes, targeted to receptors on the mitochondrial surface, and transported across or inserted into the outer and inner mitochondrial membrane before they are folded and assembled into their final native structure. This review article provides a comprehensive overview of the mechanisms and components of the mitochondrial protein import systems with a particular focus on recent developments in the field.
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Affiliation(s)
- Katja G Hansen
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany
| | - Johannes M Herrmann
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany.
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16
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Wei X, Du M, Xie J, Luo T, Zhou Y, Zhang K, Li J, Chen D, Xu P, Jia M, Zhou H, Fang H, Lyu J, Yang Y. Mutations in TOMM70 lead to multi-OXPHOS deficiencies and cause severe anemia, lactic acidosis, and developmental delay. J Hum Genet 2020; 65:231-240. [PMID: 31907385 DOI: 10.1038/s10038-019-0714-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/24/2019] [Accepted: 12/15/2019] [Indexed: 11/09/2022]
Abstract
TOM70 is a member of the TOM complex that transports cytosolic proteins into mitochondria. Here, we identified two compound heterozygous variants in TOMM70 [c.794C>T (p.T265M) and c.1745C>T (p.A582V)] from a patient with severe anemia, lactic acidosis, and developmental delay. Patient-derived immortalized lymphocytes showed decreased TOM70 expression, oligomerized TOM70 complex, and TOM 20/22/40 complex compared with expression in control lymphocytes. Functional analysis revealed that patient-derived cells exhibited multi-oxidative phosphorylation system (OXPHOS) complex defects, with complex IV being primarily affected. As a result, patient-derived cells grew slower in galactose medium and generated less ATP and more extracellular lactic acid than did control cells. In vitro cell model compensatory experiments confirmed the pathogenicity of TOMM70 variants since only wild-type TOM70, but not mutant TOM70, could restore the complex IV defect and TOM70 expression in TOM70 knockdown U2OS cells. Altogether, we report the first case of mitochondrial disease-causing mutations in TOMM70 and demonstrate that TOM70 is essential for multi-OXPHOS assembly. Mutational screening of TOMM70 should be employed to identify mitochondrial disease-causing gene mutations in the future.
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Affiliation(s)
- Xiujuan Wei
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Miaomiao Du
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Jie Xie
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Ting Luo
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Yan Zhou
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Kun Zhang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Jin Li
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Deyu Chen
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Pu Xu
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Manli Jia
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Huaibin Zhou
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Hezhi Fang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China.
| | - Jianxin Lyu
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China. .,Zhejiang Provincial People's Hospital, Affiliated People's Hospital of Hangzhou Medical College, Hangzhou, 310053, Zhejiang, China.
| | - Yanling Yang
- Department of Pediatrics, Peking University First Hospital, 100034, Beijing, China.
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17
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Vardi-Oknin D, Arava Y. Characterization of Factors Involved in Localized Translation Near Mitochondria by Ribosome-Proximity Labeling. Front Cell Dev Biol 2019; 7:305. [PMID: 31929983 PMCID: PMC6945718 DOI: 10.3389/fcell.2019.00305] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/11/2019] [Indexed: 12/13/2022] Open
Abstract
Mitochondria exert their many functions through a repertoire of hundreds of proteins. The vast majority of these proteins are encoded in the nuclear genome, translated in the cytosol and imported into the mitochondria. Current models, derived mainly from work in yeast, suggest that the translation of many of these proteins can occur in close vicinity to the mitochondria outer membrane by localized ribosomes. Here, we applied ribosome-proximity biotin labeling to address this possibility. A clear biotinylation of ribosomes by mitochondrial Tom20-BirA fusion protein was observed in a human cell line. Isolation of these ribosomes revealed their preferred association with mRNAs encoding mitochondrial proteins. Furthermore, knock down of the mitochondrial protein receptor Tom70 resulted in a decrease in ribosomes translating mRNAs encoding proteins predicted to be recognized by Tom70. Intriguingly, levels of ribosomes translating mRNAs encoding targets of Tom20 were increased. We also knocked down the RNA binding protein CLUH that is implicated in regulation of mRNA encoding mitochondrial proteins, and found an increase in association of CLUH targets with mitochondria-proximal ribosomes. This is consistent with a role for CLUH in maintaining mRNAs encoding mitochondrial proteins in the cytosol. Overall, these data shed light on factors that contribute to association of translating ribosomes with human mitochondria and may suggest a co-translational mode of protein import into this organelle.
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Affiliation(s)
- Dikla Vardi-Oknin
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel.,Program in Nanotechnology and Nanoscience, Technion - Israel Institute of Technology, Haifa, Israel
| | - Yoav Arava
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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18
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Zhang C, Wang R, Liu Z, Bunker E, Lee S, Giuntini M, Chapnick D, Liu X. The plant triterpenoid celastrol blocks PINK1-dependent mitophagy by disrupting PINK1's association with the mitochondrial protein TOM20. J Biol Chem 2019; 294:7472-7487. [PMID: 30885942 DOI: 10.1074/jbc.ra118.006506] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/05/2019] [Indexed: 12/31/2022] Open
Abstract
A critical function of the PTEN-induced kinase 1 (PINK1)-Parkin pathway is to mediate the clearing of unhealthy or damaged mitochondria via mitophagy. Loss of either PINK1 or Parkin protein expression is associated with Parkinson's disease. Here, using a high-throughput screening approach along with recombinant protein expression and kinase, immunoblotting, and immunofluorescence live-cell imaging assays, we report that celastrol, a pentacyclic triterpenoid isolated from extracts of the medicinal plant Tripterygium wilfordii, blocks recruitment pof Parkin to mitochondria, preventing mitophagy in response to mitochondrial depolarization induced by carbonyl cyanide m-chlorophenylhydrazone or to gamitrinib-induced inhibition of mitochondrial heat shock protein 90 (HSP90). Celastrol's effect on mitophagy was independent of its known role in microtubule disruption. Instead, we show that celastrol suppresses Parkin recruitment by inactivating PINK1 and preventing it from phosphorylating Parkin and also ubiquitin. We also observed that PINK1 directly and strongly associates with TOM20, a component of the translocase of outer mitochondrial membrane (TOM) machinery and relatively weak binding to another TOM subunit, TOM70. Moreover, celastrol disrupted binding between PINK1 and TOM20 both in vitro and in vivo but did not affect binding between TOM20 and TOM70. Using native gel analysis, we also show that celastrol disrupts PINK1 complex formation upon mitochondrial depolarization and sequesters PINK1 to high-molecular-weight protein aggregates. These results reveal that celastrol regulates the mitochondrial quality control pathway by interfering with PINK1-TOM20 binding.
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Affiliation(s)
- Conggang Zhang
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Rongchun Wang
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and.,the Biology Institute, Qilu University of Technology, Shandong Academy of Sciences, 28789 East Jinshi Street, Licheng District, Jinan 250103, China
| | - Zeyu Liu
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Eric Bunker
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Schuyler Lee
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Michelle Giuntini
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Douglas Chapnick
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Xuedong Liu
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
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19
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Bernadotte A, Kumar R, Winblad B, Pavlov PF. In silico identification and biochemical characterization of the human dicarboxylate clamp TPR protein interaction network. FEBS Open Bio 2018; 8:1830-1843. [PMID: 30410862 PMCID: PMC6212638 DOI: 10.1002/2211-5463.12521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/31/2018] [Accepted: 09/03/2018] [Indexed: 11/16/2022] Open
Abstract
Dicarboxylate clamp tetratricopeptide repeat (dcTPR) motif‐containing proteins are well‐known partners of the heat shock protein (Hsp) 70 and Hsp90 molecular chaperones. Together, they facilitate a variety of intracellular processes, including protein folding and maturation, protein targeting, and protein degradation. An extreme C‐terminal sequence, the EEVD motif, is identical in Hsp70 and Hsp90, and is indispensable for their interaction with dcTPR proteins. However, almost no information is available on the existence of other potential dcTPR‐interacting proteins. We searched the human protein database for proteins with C‐terminal sequences similar to that of Hsp70/Hsp90 to identify potential partners of dcTPR proteins. The search identified 112 proteins containing a Hsp70/Hsp90‐like signature at their C termini. Gene Ontology enrichment analysis of identified proteins revealed enrichment of distinct protein classes, such as molecular chaperones and proteins of the ubiquitin–proteasome system, highlighting the possibility of functional specialization of proteins containing a Hsp70/Hsp90‐like signature. We confirmed interactions of selected proteins containing Hsp70/Hsp90‐like C termini with dcTPR proteins both in vitro and in situ. Analysis of interactions of 10‐amino‐acid peptides corresponding to the C termini of identified proteins with dcTPR proteins revealed significant differences in binding strength between various peptides. We propose a hierarchical mode of interaction within the dcTPR protein network. These findings describe a novel dcTPR protein interaction networks and provide a rationale for selective regulation of protein–protein interactions within this network.
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Affiliation(s)
- Alexandra Bernadotte
- Department of Molecular Biochemistry and Biophysics Karolinska Institutet Solna Sweden.,Faculty of Mechanics and Mathematics Lomonosov Moscow State University Russia
| | - Rajnish Kumar
- Division of Neurogeriatrics Department of Neuroscience Care and Society Karolinska Institutet Huddinge Sweden
| | - Bengt Winblad
- Division of Neurogeriatrics Department of Neuroscience Care and Society Karolinska Institutet Huddinge Sweden.,Memory Clinic Theme Aging Karolinska University Hospital Huddinge Sweden
| | - Pavel F Pavlov
- Division of Neurogeriatrics Department of Neuroscience Care and Society Karolinska Institutet Huddinge Sweden.,Memory Clinic Theme Aging Karolinska University Hospital Huddinge Sweden
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20
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Kodiha M, Flamant E, Wang YM, Stochaj U. Defining the short-term effects of pharmacological 5'-AMP activated kinase modulators on mitochondrial polarization, morphology and heterogeneity. PeerJ 2018; 6:e5469. [PMID: 30186684 PMCID: PMC6119600 DOI: 10.7717/peerj.5469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/27/2018] [Indexed: 01/09/2023] Open
Abstract
Background Under aerobic growth conditions, mitochondria are the major producers of cellular ATP and crucial for the proper performance of organs and tissues. This applies especially to cells with high energy demand, such as the renal proximal tubule epithelium. Mitochondrial dysfunction contributes to the pathology of human health conditions, including various kidney diseases. The improvement of mitochondrial function ameliorates some of these pathologies. This can potentially be achieved with pharmacological compounds. For example, long-term treatment with activators of 5'-AMP activated kinase (AMPK) enhances mitochondrial biogenesis. However, pharmacological damage control during acute cell injury requires that the short-term effects of these compounds and the impact on healthy cells are also understood. It was our objective to define the changes elicited by established modulators of AMPK activity in healthy renal proximal tubule cells. Methods Our work combines confocal microscopy with quantitative image analysis, 3D image reconstruction and Western blotting to provide novel insights into the biology of mitochondria. Specifically, we evaluated the effects of pharmacological AMPK modulators (compound C, AICAR, phenformin, resveratrol) on mitochondrial polarization, morphology and heterogeneity. Microscopic studies generated information at the single cell and subcellular levels. Our research focused on LLC-PK1 cells that are derived from the renal proximal tubule. Mitochondrial heterogeneity was also examined in MCF7 breast cancer cells. Results Pharmacological agents that affect AMPK activity in renal proximal tubule cells can alter mitochondrial organization and the electrochemical potential across the inner mitochondrial membrane. These changes were compound-specific. Short-term incubation with the AMPK inhibitor compound C caused mitochondrial hyperpolarization. This was accompanied by mitochondrial fragmentation. By contrast, AMPK activators AICAR, phenformin and resveratrol had little impact. We further show that the biological properties of mitochondria are determined by their subcellular location. Mitochondria at the cell periphery displayed higher MitoTracker/Tom70 values as compared to organelles located in the vicinity of the nucleus. This was not limited to renal proximal tubule cells, but also observed in MCF7 cells. Pharmacological AMPK modulators altered these location-dependent properties in a compound-specific fashion. While the region-dependent differences were enhanced with phenformin, they were ameliorated by resveratrol. Discussion We evaluated the rapid changes in mitochondrial characteristics that are induced by pharmacological AMPK modulators. Our research supports the concept that pharmacological agents that target AMPK can rearrange mitochondrial networks at the single cell level. Collectively, these insights are relevant to the development of proper strategies for the short-term adjustment of mitochondrial performance.
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Affiliation(s)
- Mohamed Kodiha
- Department of Physiology, McGill University, Montreal, Canada
| | - Etienne Flamant
- Department of Physiology, McGill University, Montreal, Canada
| | - Yi Meng Wang
- Department of Physiology, McGill University, Montreal, Canada
| | - Ursula Stochaj
- Department of Physiology, McGill University, Montreal, Canada
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21
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Backes S, Hess S, Boos F, Woellhaf MW, Gödel S, Jung M, Mühlhaus T, Herrmann JM. Tom70 enhances mitochondrial preprotein import efficiency by binding to internal targeting sequences. J Cell Biol 2018; 217:1369-1382. [PMID: 29382700 PMCID: PMC5881500 DOI: 10.1083/jcb.201708044] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 12/12/2017] [Accepted: 01/17/2018] [Indexed: 11/22/2022] Open
Abstract
N-terminal matrix-targeting signals (MTSs) are critical for mitochondrial protein import. Backes et al. identified additional internal MTS-like sequences scattered along the sequences of mitochondrial proteins. By binding to Tom70 on the mitochondrial surface, these sequences support the import process. The biogenesis of mitochondria depends on the import of hundreds of preproteins. N-terminal matrix-targeting signals (MTSs) direct preproteins to the surface receptors Tom20, Tom22, and Tom70. In this study, we show that many preproteins contain additional internal MTS-like signals (iMTS-Ls) in their mature region that share the characteristic properties of presequences. These features allow the in silico prediction of iMTS-Ls. Using Atp1 as model substrate, we show that iMTS-Ls mediate the binding to Tom70 and have the potential to target the protein to mitochondria if they are presented at its N terminus. The import of preproteins with high iMTS-L content is significantly impaired in the absence of Tom70, whereas preproteins with low iMTS-L scores are less dependent on Tom70. We propose a stepping stone model according to which the Tom70-mediated interaction with internal binding sites improves the import competence of preproteins and increases the efficiency of their translocation into the mitochondrial matrix.
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Affiliation(s)
- Sandra Backes
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Steffen Hess
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | | | - Sabrina Gödel
- Computational Systems Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Martin Jung
- Medical Biochemistry, Saarland University, Homburg, Germany
| | - Timo Mühlhaus
- Computational Systems Biology, University of Kaiserslautern, Kaiserslautern, Germany
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TOM70 Sustains Cell Bioenergetics by Promoting IP3R3-Mediated ER to Mitochondria Ca 2+ Transfer. Curr Biol 2018; 28:369-382.e6. [PMID: 29395920 DOI: 10.1016/j.cub.2017.12.047] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 11/22/2017] [Accepted: 12/20/2017] [Indexed: 01/09/2023]
Abstract
The mitochondrial translocase of the outer membrane (TOM) is a protein complex that is essential for the post-translational import of nuclear-encoded mitochondrial proteins. Among its subunits, TOM70 and TOM20 are only transiently associated with the core complex, suggesting their possible additional roles within the outer mitochondrial membrane (OMM). Here, by using different mammalian cell lines, we demonstrate that TOM70, but not TOM20, clusters in distinct OMM foci, frequently overlapping with sites in which the endoplasmic reticulum (ER) contacts mitochondria. Functionally, TOM70 depletion specifically impairs inositol trisphosphates (IP3)-linked ER to mitochondria Ca2+ transfer. This phenomenon is dependent on the capacity of TOM70 to interact with IP3-receptors and favor their functional recruitment close to mitochondria. Importantly, the reduced constitutive Ca2+ transfer to mitochondria, observed in TOM70-depleted cells, dampens mitochondrial respiration, affects cell bioenergetics, induces autophagy, and inhibits proliferation. Our data reveal a hitherto unexpected role for TOM70 in pro-survival ER-mitochondria communication, reinforcing the view that the ER-mitochondria signaling platform is a key regulator of cell fate.
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Backes S, Herrmann JM. Protein Translocation into the Intermembrane Space and Matrix of Mitochondria: Mechanisms and Driving Forces. Front Mol Biosci 2017; 4:83. [PMID: 29270408 PMCID: PMC5725982 DOI: 10.3389/fmolb.2017.00083] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 11/24/2017] [Indexed: 11/17/2022] Open
Abstract
Mitochondria contain two aqueous subcompartments, the matrix and the intermembrane space (IMS). The matrix is enclosed by both the inner and outer mitochondrial membranes, whilst the IMS is sandwiched between the two. Proteins of the matrix are synthesized in the cytosol as preproteins, which contain amino-terminal matrix targeting sequences that mediate their translocation through translocases embedded in the outer and inner membrane. For these proteins, the translocation reaction is driven by the import motor which is part of the inner membrane translocase. The import motor employs matrix Hsp70 molecules and ATP hydrolysis to ratchet proteins into the mitochondrial matrix. Most IMS proteins lack presequences and instead utilize the IMS receptor Mia40, which facilitates their translocation across the outer membrane in a reaction that is coupled to the formation of disulfide bonds within the protein. This process requires neither ATP nor the mitochondrial membrane potential. Mia40 fulfills two roles: First, it acts as a holdase, which is crucial in the import of IMS proteins and second, it functions as a foldase, introducing disulfide bonds into newly imported proteins, which induces and stabilizes their natively folded state. For several Mia40 substrates, oxidative folding is an essential prerequisite for their assembly into oligomeric complexes. Interestingly, recent studies have shown that the two functions of Mia40 can be experimentally separated from each other by the use of specific mutants, hence providing a powerful new way to dissect the different physiological roles of Mia40. In this review we summarize the current knowledge relating to the mitochondrial matrix-targeting and the IMS-targeting/Mia40 pathway. Moreover, we discuss the mechanistic properties by which the mitochondrial import motor on the one hand and Mia40 on the other, drive the translocation of their substrates into the organelle. We propose that the lateral diffusion of Mia40 in the inner membrane and the oxidation-mediated folding of incoming polypeptides supports IMS import.
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Affiliation(s)
- Sandra Backes
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
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24
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Xue Q, Pei H, Liu Q, Zhao M, Sun J, Gao E, Ma X, Tao L. MICU1 protects against myocardial ischemia/reperfusion injury and its control by the importer receptor Tom70. Cell Death Dis 2017; 8:e2923. [PMID: 28703803 PMCID: PMC5550843 DOI: 10.1038/cddis.2017.280] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 04/21/2017] [Accepted: 05/15/2017] [Indexed: 01/26/2023]
Abstract
Mitochondrial Ca2+ overload is a main contributor to mitochondrial damage hence cardiomyocyte death in myocardial ischemia/reperfusion (MI/R) injury. MICU1 has been recently identified as an important regulator of mitochondrial Ca2+ homeostasis. Here we try to identify the role of MICU1 in MI/R, and to investigate whether the mitochondrial importer receptor Tom70 possesses critical roles in the mitochondrial translocation of MICU1 and MI/R. Specific small interfering RNA (20 μg) against MICU1 and Tom70, and lentivirus vectors carrying the Tom70a sequences (3.3 × 107 TU) were delivered through intramyocardial injection. Seventy-two hours after injection, mice were subjected to 30 min of MI followed by 3 h (for cell apoptosis and mitochondrial damage assessment) or 24 h (for cardiac function and infarct size determination) of reperfusion. MI/R had no significant effect on total MICU1 expression, but caused significant reduction of MICU1 in mitochondria. Knockdown of MICU1 significantly aggravated MI/R injury, as evidenced by enlarged infarct size, depressed cardiac function and increased myocardial apoptosis. Moreover, MICU1 deficiency resulted in markedly aggravated mitochondrial Ca2+ overload, consequently destructed mitochondrial morphology and suppressed mitochondrial function (evidenced by decreased ATP production). Interestingly, mitochondrial Tom70 was also decreased in MI/R. Genetic loss-function study revealed that mitochondrial MICU1 expression was depressed by Tom70 ablation. Furthermore, Tom70 deficiency significantly aggravated MI/R injury and worsened mitochondrial Ca2+ overload. However, supplementation of Tom70 significantly attenuated MI/R injury, preserved mitochondrial morphology and function, and inhibited mitochondrial Ca2+ overload, all of which were abolished by MICU1 suppression. Mitochondrial Tom70/MICU1 pathway protects against MI/R injury, in which mitochondrial localization of MICU1 is governed by Tom70, and MICU1 serves as an indispensable factor in Tom70’s cardioprotection.
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Affiliation(s)
- Qiang Xue
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Haifeng Pei
- Department of Cardiology, Chengdu Military General Hospital, Chengdu 610083, China
| | - Qinshe Liu
- Shaanxi University of Chinese Medicine, Xi'an 712046, China
| | - Mingjun Zhao
- Shaanxi University of Chinese Medicine, Xi'an 712046, China
| | - Jing Sun
- Shaanxi University of Chinese Medicine, Xi'an 712046, China
| | - Erhe Gao
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Xinliang Ma
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Ling Tao
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
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25
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Zanphorlin LM, Lima TB, Wong MJ, Balbuena TS, Minetti CASA, Remeta DP, Young JC, Barbosa LRS, Gozzo FC, Ramos CHI. Heat Shock Protein 90 kDa (Hsp90) Has a Second Functional Interaction Site with the Mitochondrial Import Receptor Tom70. J Biol Chem 2016; 291:18620-31. [PMID: 27402847 PMCID: PMC5009240 DOI: 10.1074/jbc.m115.710137] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 07/07/2016] [Indexed: 12/19/2022] Open
Abstract
To accomplish its crucial role, mitochondria require proteins that are produced in the cytosol, delivered by cytosolic Hsp90, and translocated to its interior by the translocase outer membrane (TOM) complex. Hsp90 is a dimeric molecular chaperone and its function is modulated by its interaction with a large variety of co-chaperones expressed within the cell. An important family of co-chaperones is characterized by the presence of one TPR (tetratricopeptide repeat) domain, which binds to the C-terminal MEEVD motif of Hsp90. These include Tom70, an important component of the TOM complex. Despite a wealth of studies conducted on the relevance of Tom70·Hsp90 complex formation, there is a dearth of information regarding the exact molecular mode of interaction. To help fill this void, we have employed a combined experimental strategy consisting of cross-linking/mass spectrometry to investigate binding of the C-terminal Hsp90 domain to the cytosolic domain of Tom70. This approach has identified a novel region of contact between C-Hsp90 and Tom70, a finding that is confirmed by probing the corresponding peptides derived from cross-linking experiments via isothermal titration calorimetry and mitochondrial import assays. The data generated in this study are combined to input constraints for a molecular model of the Hsp90/Tom70 interaction, which has been validated by small angle x-ray scattering, hydrogen/deuterium exchange, and mass spectrometry. The resultant model suggests that only one of the MEEVD motifs within dimeric Hsp90 contacts Tom70. Collectively, our findings provide significant insight on the mechanisms by which preproteins interact with Hsp90 and are translocated via Tom70 to the mitochondria.
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Affiliation(s)
- Leticia M Zanphorlin
- From the Institute of Chemistry, University of Campinas UNICAMP, Campinas SP, 13083-970, Brazil
| | - Tatiani B Lima
- From the Institute of Chemistry, University of Campinas UNICAMP, Campinas SP, 13083-970, Brazil
| | - Michael J Wong
- the Department of Biochemistry, McGill University, Groupe de Recherche Axé sur la Structure des Protéines, Montreal, QC H3G 0B1, Canada
| | - Tiago S Balbuena
- the College of Agricultural and Veterinary Sciences, State University of Sao Paulo, Jaboticabal, Sao Paulo, 14884-900 Brazil
| | - Conceição A S A Minetti
- the Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, and
| | - David P Remeta
- the Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, and
| | - Jason C Young
- the Department of Biochemistry, McGill University, Groupe de Recherche Axé sur la Structure des Protéines, Montreal, QC H3G 0B1, Canada
| | - Leandro R S Barbosa
- the Instituto de Fisica, Universidade de Sao Paulo USP, Sao Paulo SP, 05508-090 Brazil
| | - Fabio C Gozzo
- From the Institute of Chemistry, University of Campinas UNICAMP, Campinas SP, 13083-970, Brazil
| | - Carlos H I Ramos
- From the Institute of Chemistry, University of Campinas UNICAMP, Campinas SP, 13083-970, Brazil,
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Hwang HJ, Dornbos P, Steidemann M, Dunivin TK, Rizzo M, LaPres JJ. Mitochondrial-targeted aryl hydrocarbon receptor and the impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin on cellular respiration and the mitochondrial proteome. Toxicol Appl Pharmacol 2016; 304:121-32. [PMID: 27105554 DOI: 10.1016/j.taap.2016.04.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/02/2016] [Accepted: 04/08/2016] [Indexed: 11/18/2022]
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor within the Per-Arnt-Sim (PAS) domain superfamily. Exposure to the most potent AHR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is associated with various pathological effects including metabolic syndrome. While research over the last several years has demonstrated a role for oxidative stress and metabolic dysfunction in AHR-dependent TCDD-induced toxicity, the role of the mitochondria in this process has not been fully explored. Our previous research suggested that a portion of the cellular pool of AHR could be found in the mitochondria (mitoAHR). Using a protease protection assay with digitonin extraction, we have now shown that this mitoAHR is localized to the inter-membrane space (IMS) of the organelle. TCDD exposure induced a degradation of mitoAHR similar to that of cytosolic AHR. Furthermore, siRNA-mediated knockdown revealed that translocase of outer-mitochondrial membrane 20 (TOMM20) was involved in the import of AHR into the mitochondria. In addition, TCDD altered cellular respiration in an AHR-dependent manner to maintain respiratory efficiency as measured by oxygen consumption rate (OCR). Stable isotope labeling by amino acids in cell culture (SILAC) identified a battery of proteins within the mitochondrial proteome influenced by TCDD in an AHR-dependent manner. Among these, 17 proteins with fold changes≥2 are associated with various metabolic pathways, suggesting a role of mitochondrial retrograde signaling in TCDD-mediated pathologies. Collectively, these studies suggest that mitoAHR is localized to the IMS and AHR-dependent TCDD-induced toxicity, including metabolic dysfunction, wasting syndrome, and hepatic steatosis, involves mitochondrial dysfunction.
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Affiliation(s)
- Hye Jin Hwang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48824, United States
| | - Peter Dornbos
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Institute for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1319, United States
| | - Michelle Steidemann
- Institute for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1319, United States; Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, United States
| | - Taylor K Dunivin
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, United States
| | - Mike Rizzo
- Institute for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1319, United States; Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, MI 48824, United States
| | - John J LaPres
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48824, United States.
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Abstract
UNLABELLED Virus infection triggers immediate innate immune responses. Apoptosis represents another effective means to restrict virus invasion, besides robust expression of host cytokines and chemokines. IRF3 was recently demonstrated to be indispensable for Sendai virus (SeV)-induced apoptosis, but the underlying mechanism is not fully understood. Here we report that a dynamic protein complex, Tom70/Hsp90/IRF3/Bax, mediates SeV-induced apoptosis. The cytosolic proapoptotic protein Bax interacts specifically with IRF3 upon virus infection. The mitochondrial outer membrane protein Tom70 recruits IRF3 to mitochondria via Hsp90. Consequently, the relocation of Bax onto mitochondria induces the leakage of cytochrome c into the cytosol and initiates the corresponding apoptosis. Interestingly, IKK-i is essential for this apoptosis, whereas TBK1 is dispensable. Collectively, our study characterizes a novel protein complex that is important for SeV-induced apoptosis. IMPORTANCE Apoptosis is an effective means of sacrificing virus-infected cells and restraining the spread of virus. In this study, we demonstrate that IRF3 associates with Bax upon virus infection. Tom70 recruits this protein complex to the mitochondrial outer membrane through Hsp90, which thus induces the release of cytochrome c into the cytosol, initiating virus-induced apoptosis. Interestingly, IKK-i plays an essential role in this activation. This study uncovers a novel mechanism of SeV-induced apoptosis.
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Reikvam H, Brenner AK, Nepstad I, Sulen A, Bruserud Ø. Heat shock protein 70 – the next chaperone to target in the treatment of human acute myelogenous leukemia? Expert Opin Ther Targets 2014; 18:929-44. [DOI: 10.1517/14728222.2014.924925] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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29
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Mitochondrial protein translocases for survival and wellbeing. FEBS Lett 2014; 588:2484-95. [DOI: 10.1016/j.febslet.2014.05.028] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 05/15/2014] [Accepted: 05/15/2014] [Indexed: 11/20/2022]
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30
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Woellhaf MW, Hansen KG, Garth C, Herrmann JM. Import of ribosomal proteins into yeast mitochondria. Biochem Cell Biol 2014; 92:489-98. [PMID: 24943357 DOI: 10.1139/bcb-2014-0029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Mitochondrial ribosomes of baker's yeast contain at least 78 protein subunits. All but one of these proteins are nuclear-encoded, synthesized on cytosolic ribosomes, and imported into the matrix for biogenesis. The import of matrix proteins typically relies on N-terminal mitochondrial targeting sequences that form positively charged amphipathic helices. Interestingly, the N-terminal regions of many ribosomal proteins do not closely match the characteristics of matrix targeting sequences, suggesting that the import processes of these proteins might deviate to some extent from the general import route. So far, the biogenesis of only two ribosomal proteins, Mrpl32 and Mrp10, was studied experimentally and indeed showed surprising differences to the import of other preproteins. In this review article we summarize the current knowledge on the transport of proteins into the mitochondrial matrix, and thereby specifically focus on proteins of the mitochondrial ribosome.
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Affiliation(s)
- Michael W Woellhaf
- a Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663 Kaiserslautern, Germany
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31
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van den Akker EB, Passtoors WM, Jansen R, van Zwet EW, Goeman JJ, Hulsman M, Emilsson V, Perola M, Willemsen G, Penninx BW, Heijmans BT, Maier AB, Boomsma DI, Kok JN, Slagboom PE, Reinders MJ, Beekman M. Meta-analysis on blood transcriptomic studies identifies consistently coexpressed protein-protein interaction modules as robust markers of human aging. Aging Cell 2014; 13:216-25. [PMID: 24119000 PMCID: PMC4331790 DOI: 10.1111/acel.12160] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2013] [Indexed: 11/30/2022] Open
Abstract
The bodily decline that occurs with advancing age strongly impacts on the prospects for future health and life expectancy. Despite the profound role of age in disease etiology, knowledge about the molecular mechanisms driving the process of aging in humans is limited. Here, we used an integrative network-based approach for combining multiple large-scale expression studies in blood (2539 individuals) with protein–protein Interaction (PPI) data for the detection of consistently coexpressed PPI modules that may reflect key processes that change throughout the course of normative aging. Module detection followed by a meta-analysis on chronological age identified fifteen consistently coexpressed PPI modules associated with chronological age, including a highly significant module (P = 3.5 × 10−38) enriched for ‘T-cell activation’ marking age-associated shifts in lymphocyte blood cell counts (R2 = 0.603; P = 1.9 × 10−10). Adjusting the analysis in the compendium for the ‘T-cell activation’ module showed five consistently coexpressed PPI modules that robustly associated with chronological age and included modules enriched for ‘Translational elongation’, ‘Cytolysis’ and ‘DNA metabolic process’. In an independent study of 3535 individuals, four of five modules consistently associated with chronological age, underpinning the robustness of the approach. We found three of five modules to be significantly enriched with aging-related genes, as defined by the GenAge database, and association with prospective survival at high ages for one of the modules including ASF1A. The hereby-detected age-associated and consistently coexpressed PPI modules therefore may provide a molecular basis for future research into mechanisms underlying human aging.
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Affiliation(s)
- Erik B. van den Akker
- Department of Molecular Epidemiology; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
- The Delft Bioinformatics Lab; Delft University of Technology; PO Box 5031 2600 GA Delft The Netherlands
| | - Willemijn M. Passtoors
- Department of Molecular Epidemiology; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
| | - Rick Jansen
- Department of Psychiatry; VU University Medical Center; Neuroscience Campus Amsterdam; VU University Medical Center; A.J. Ernststraat 1187 1081 HL Amsterdam The Netherlands
- EMGO Institute for Health and Care Research; Neuroscience Campus Amsterdam; Van der Boechorststraat 7 1081 BT Amsterdam The Netherlands
| | - Erik W. van Zwet
- Department of Medical Statistics; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
| | - Jelle J. Goeman
- Department of Medical Statistics; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
| | - Marc Hulsman
- The Delft Bioinformatics Lab; Delft University of Technology; PO Box 5031 2600 GA Delft The Netherlands
| | - Valur Emilsson
- Icelandic Heart Association; Holtasmari 1 IS-201 Kópavogur Iceland
| | - Markus Perola
- National Institute for Health and Welfare; PO Box 30 00271 Helsinki Finland
| | - Gonneke Willemsen
- Department of Biological Psychology; VU University; Van der Boechorststraat 7 1081 BT Amsterdam The Netherlands
| | - Brenda W.J.H. Penninx
- Department of Psychiatry; VU University Medical Center; Neuroscience Campus Amsterdam; VU University Medical Center; A.J. Ernststraat 1187 1081 HL Amsterdam The Netherlands
- EMGO Institute for Health and Care Research; Neuroscience Campus Amsterdam; Van der Boechorststraat 7 1081 BT Amsterdam The Netherlands
| | - Bas T. Heijmans
- Department of Molecular Epidemiology; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
| | - Andrea B. Maier
- Section of Gerontology and Geriatrics; Department of Internal Medicine; VU University Medical Center; De Boelelaan 1117 1007 MB Amsterdam The Netherlands
| | - Dorret I. Boomsma
- EMGO Institute for Health and Care Research; Neuroscience Campus Amsterdam; Van der Boechorststraat 7 1081 BT Amsterdam The Netherlands
- Department of Biological Psychology; VU University; Van der Boechorststraat 7 1081 BT Amsterdam The Netherlands
| | - Joost N. Kok
- Department of Molecular Epidemiology; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
- Department of Algorithms; Leiden Institute of Advanced Computer Science; University of Leiden; Niels Bohrweg 1 2333 CA Leiden The Netherlands
| | - Pieternella E. Slagboom
- Department of Molecular Epidemiology; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
- Netherlands Consortium for Healthy Ageing; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
| | - Marcel J.T. Reinders
- The Delft Bioinformatics Lab; Delft University of Technology; PO Box 5031 2600 GA Delft The Netherlands
| | - Marian Beekman
- Department of Molecular Epidemiology; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
- Netherlands Consortium for Healthy Ageing; Leiden University Medical Center; PO Box 9600 2300 RC Leiden The Netherlands
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Jiang Y, Liu X, Li S, Zhang Y, Piao F, Sun X. Identification of differentially expressed proteins related to organophosphorus-induced delayed neuropathy in the brains of hens. J Appl Toxicol 2013; 34:1352-60. [PMID: 24338829 DOI: 10.1002/jat.2965] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 10/17/2013] [Accepted: 10/22/2013] [Indexed: 12/17/2022]
Abstract
Some organophosphorus compounds can cause organophosphate-induced delayed neuropathy (OPIDN). Incidents have been documented for decades, however, little is known about which proteins contribute to the initiation, progression and development of OPIDN. In this study, 51 hens were divided into three groups. The tri-ortho-cresyl-phosphate (TOCP) group was treated with 1000 mg kg(-1) TOCP whereas the control group was treated with an equivalent volume of vehicle. The PMSF + TOCP group was treated subcutaneously with 40 mg kg(-1) phenylmethylsulfonyl fluoride (PMSF), followed by 1000 mg kg(-1) TOCP 24 h later. Proteins in the brains of hens were separated by two-dimensional polyacrylamide gel electrophoresis on day 5 after TOCP administration. Mass spectrometry identified eight differentially expressed proteins. Among these proteins, downregulated expression of glutamine synthetase (GS) in the brains of hens after TOCP treatment was further confirmed by real time RT-PCR and ELISA. Moreover, the brains of hens exposed to TOCP exhibited increased levels of glutamate (Glu) and cytosolic calcium concentration ([Ca(2+)](i)), and a decreased level of glutamine (Gln). However, there were no significant differences in GS expression or levels of Glu, Gln, and [Ca(2+)](i) in the brains of hens among the groups on day 21 after TOCP administration. These results indicate that TOCP exposure downregulates GS expression in the brains of hens, and that downregulation of GS is accompanied by increased levels of Glu and [Ca(2+)](i) in the early stage after TOCP administration. It is also suggested that the downregulated expression of GS might be associated with OPIDN through the disruption of homeostasis of the Glu-Gln cycle and [Ca(2+) ](i).
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Affiliation(s)
- Ying Jiang
- Department of Occupational and Environmental of Health, Dalian Medical University, No. 9 Western Section of Lushun South Road, Dalian, Liaoning, 116044, China
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Profiling of Parkin-binding partners using tandem affinity purification. PLoS One 2013; 8:e78648. [PMID: 24244333 PMCID: PMC3823883 DOI: 10.1371/journal.pone.0078648] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 09/15/2013] [Indexed: 11/19/2022] Open
Abstract
Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting approximately 1-2% of the general population over age 60. It is characterized by a rather selective loss of dopaminergic neurons in the substantia nigra and the presence of α-synuclein-enriched Lewy body inclusions. Mutations in the Parkin gene (PARK2) are the major cause of autosomal recessive early-onset parkinsonism. The Parkin protein is an E3 ubiquitin ligase with various cellular functions, including the induction of mitophagy upon mitochondrial depolarizaton, but the full repertoire of Parkin-binding proteins remains poorly defined. Here we employed tandem affinity purification interaction screens with subsequent mass spectrometry to profile binding partners of Parkin. Using this approach for two different cell types (HEK293T and SH-SY5Y neuronal cells), we identified a total of 203 candidate Parkin-binding proteins. For the candidate proteins and the proteins known to cause heritable forms of parkinsonism, protein-protein interaction data were derived from public databases, and the associated biological processes and pathways were analyzed and compared. Functional similarity between the candidates and the proteins involved in monogenic parkinsonism was investigated, and additional confirmatory evidence was obtained using published genetic interaction data from Drosophila melanogaster. Based on the results of the different analyses, a prioritization score was assigned to each candidate Parkin-binding protein. Two of the top ranking candidates were tested by co-immunoprecipitation, and interaction to Parkin was confirmed for one of them. New candidates for involvement in cell death processes, protein folding, the fission/fusion machinery, and the mitophagy pathway were identified, which provide a resource for further elucidating Parkin function.
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Kulawiak B, Höpker J, Gebert M, Guiard B, Wiedemann N, Gebert N. The mitochondrial protein import machinery has multiple connections to the respiratory chain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:612-26. [PMID: 23274250 DOI: 10.1016/j.bbabio.2012.12.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/12/2012] [Accepted: 12/17/2012] [Indexed: 01/09/2023]
Abstract
The mitochondrial inner membrane harbors the complexes of the respiratory chain and protein translocases required for the import of mitochondrial precursor proteins. These complexes are functionally interdependent, as the import of respiratory chain precursor proteins across and into the inner membrane requires the membrane potential. Vice versa the membrane potential is generated by the proton pumping complexes of the respiratory chain. Besides this basic codependency four different systems for protein import, processing and assembly show further connections to the respiratory chain. The mitochondrial intermembrane space import and assembly machinery oxidizes cysteine residues within the imported precursor proteins and is able to donate the liberated electrons to the respiratory chain. The presequence translocase of the inner membrane physically interacts with the respiratory chain. The mitochondrial processing peptidase is homologous to respiratory chain subunits and the carrier translocase of the inner membrane even shares a subunit with the respiratory chain. In this review we will summarize the import of mitochondrial precursor proteins and highlight these special links between the mitochondrial protein import machinery and the respiratory chain. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Affiliation(s)
- Bogusz Kulawiak
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, Freiburg, Germany
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Ferramosca A, Zara V. Biogenesis of mitochondrial carrier proteins: molecular mechanisms of import into mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012. [PMID: 23201437 DOI: 10.1016/j.bbamcr.2012.11.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Mitochondrial metabolite carriers are hydrophobic proteins which catalyze the flux of several charged or hydrophilic substrates across the inner membrane of mitochondria. These proteins, like most mitochondrial proteins, are nuclear encoded and after their synthesis in the cytosol are transported into the inner mitochondrial membrane. Most metabolite carriers, differently from other nuclear encoded mitochondrial proteins, are synthesized without a cleavable presequence and contain several, poorly characterized, internal targeting signals. However, an interesting aspect is the presence of a positively charged N-terminal presequence in a limited number of mitochondrial metabolite carriers. Over the last few years the molecular mechanisms of import of metabolite carrier proteins into mitochondria have been thoroughly investigated. This review summarizes the present knowledge and discusses recent advances on the import and sorting of mitochondrial metabolite carriers.
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Affiliation(s)
- Alessandra Ferramosca
- Department of Environmental and Biological Sciences and Technologies, University of Salento, Lecce, Italy
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Nargang FE, Adames K, Rüb C, Cheung S, Easton N, Nargang CE, Chae MS. Identification of genes required for alternative oxidase production in the Neurospora crassa gene knockout library. G3 (BETHESDA, MD.) 2012; 2:1345-56. [PMID: 23173086 PMCID: PMC3484665 DOI: 10.1534/g3.112.004218] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 09/04/2012] [Indexed: 01/22/2023]
Abstract
The alternative oxidase (AOX) of Neurospora crassa transfers electrons from ubiquinol to oxygen. The enzyme is not expressed under normal conditions. However, when the function of the standard electron transport chain is compromised, AOX is induced, providing cells with a means to continue respiration and growth. Induction of the enzyme represents a form of retrograde regulation because AOX is encoded by a nuclear gene that responds to signals produced from inefficiently functioning mitochondria. To identify genes required for AOX expression, we have screened the N. crassa gene knockout library for strains that are unable to grow in the presence of antimycin A, an inhibitor of complex III of the standard electron transport chain. From the 7800 strains containing knockouts of different genes, we identified 62 strains that have reduced levels of AOX when grown under conditions known to induce the enzyme. Some strains have virtually no AOX, whereas others have only a slight reduction of the protein. A broad range of seemingly unrelated functions are represented in the knockouts. For example, we identified transcription factors, kinases, the mitochondrial import receptor Tom70, three subunits of the COP9 signalosome, a monothiol glutaredoxin, and several hypothetical proteins as being required for wild-type levels of AOX production. Our results suggest that defects in many signaling or metabolic pathways have a negative effect on AOX expression and imply that complex systems control production of the enzyme.
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Affiliation(s)
- Frank E Nargang
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
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Faou P, Hoogenraad NJ. Tom34: A cytosolic cochaperone of the Hsp90/Hsp70 protein complex involved in mitochondrial protein import. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:348-57. [DOI: 10.1016/j.bbamcr.2011.12.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 11/17/2011] [Accepted: 12/02/2011] [Indexed: 10/14/2022]
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Abstract
Depending on the organism, mitochondria consist approximately of 500-1,400 different proteins. By far most of these proteins are encoded by nuclear genes and synthesized on cytosolic ribosomes. Targeting signals direct these proteins into mitochondria and there to their respective subcompartment: the outer membrane, the intermembrane space (IMS), the inner membrane, and the matrix. Membrane-embedded translocation complexes allow the translocation of proteins across and, in the case of membrane proteins, the insertion into mitochondrial membranes. A small number of proteins are encoded by the mitochondrial genome: Most mitochondrial translation products represent hydrophobic proteins of the inner membrane which-together with many nuclear-encoded proteins-form the respiratory chain complexes. This chapter gives an overview on the mitochondrial protein translocases and the mechanisms by which they drive the transport and assembly of mitochondrial proteins.
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