1
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Kim J, Goldstein M, Zecchel L, Ghorayeb R, Maxwell CA, Weidberg H. ATAD1 prevents clogging of TOM and damage caused by un-imported mitochondrial proteins. Cell Rep 2024; 43:114473. [PMID: 39024102 DOI: 10.1016/j.celrep.2024.114473] [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: 10/06/2023] [Revised: 05/26/2024] [Accepted: 06/24/2024] [Indexed: 07/20/2024] Open
Abstract
Mitochondria require the constant import of nuclear-encoded proteins for proper functioning. Impaired protein import not only depletes mitochondria of essential factors but also leads to toxic accumulation of un-imported proteins outside the organelle. Here, we investigate the consequences of impaired mitochondrial protein import in human cells. We demonstrate that un-imported proteins can clog the mitochondrial translocase of the outer membrane (TOM). ATAD1, a mitochondrial ATPase, removes clogged proteins from TOM to clear the entry gate into the mitochondria. ATAD1 interacts with both TOM and stalled proteins, and its knockout results in extensive accumulation of mitochondrial precursors as well as decreased protein import. Increased ATAD1 expression contributes to improved fitness of cells with inefficient mitochondrial protein import. Overall, we demonstrate the importance of the ATAD1 quality control pathway in surveilling protein import and its contribution to cellular health.
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Affiliation(s)
- John Kim
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Madeleine Goldstein
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Lauren Zecchel
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Ryan Ghorayeb
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
| | - Christopher A Maxwell
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada; Michael Cuccione Childhood Cancer Research Program, British Columbia Children's Hospital, Vancouver, BC, Canada
| | - Hilla Weidberg
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada.
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2
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Somasundaram I, Jain SM, Blot-Chabaud M, Pathak S, Banerjee A, Rawat S, Sharma NR, Duttaroy AK. Mitochondrial dysfunction and its association with age-related disorders. Front Physiol 2024; 15:1384966. [PMID: 39015222 PMCID: PMC11250148 DOI: 10.3389/fphys.2024.1384966] [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: 02/12/2024] [Accepted: 06/10/2024] [Indexed: 07/18/2024] Open
Abstract
Aging is a complex process that features a functional decline in many organelles. Various factors influence the aging process, such as chromosomal abnormalities, epigenetic changes, telomere shortening, oxidative stress, and mitochondrial dysfunction. Mitochondrial dysfunction significantly impacts aging because mitochondria regulate cellular energy, oxidative balance, and calcium levels. Mitochondrial integrity is maintained by mitophagy, which helps maintain cellular homeostasis, prevents ROS production, and protects against mtDNA damage. However, increased calcium uptake and oxidative stress can disrupt mitochondrial membrane potential and permeability, leading to the apoptotic cascade. This disruption causes increased production of free radicals, leading to oxidative modification and accumulation of mitochondrial DNA mutations, which contribute to cellular dysfunction and aging. Mitochondrial dysfunction, resulting from structural and functional changes, is linked to age-related degenerative diseases. This review focuses on mitochondrial dysfunction, its implications in aging and age-related disorders, and potential anti-aging strategies through targeting mitochondrial dysfunction.
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Affiliation(s)
- Indumathi Somasundaram
- Biotechnology Engineering, Kolhapur Institute of Technology’s College of Engineering, Kolhapur, India
| | - Samatha M. Jain
- Department of Biotechnology, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Chennai, India
| | | | - Surajit Pathak
- Department of Biotechnology, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Chennai, India
| | - Antara Banerjee
- Department of Biotechnology, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Chennai, India
| | - Sonali Rawat
- Stem Cell Facility, DBT-Centre of Excellence for Stem Cell Research, All India Institute of Medical Sciences, New Delhi, India
| | - Neeta Raj Sharma
- School of Bioengineering and Biosciences, Lovely Professional University, Phagwara, India
| | - Asim K. Duttaroy
- Department of Nutrition, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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3
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Xiao T, English AM, Wilson ZN, Maschek J, Cox JE, Hughes AL. The phospholipids cardiolipin and phosphatidylethanolamine differentially regulate MDC biogenesis. J Cell Biol 2024; 223:e202302069. [PMID: 38497895 PMCID: PMC10949074 DOI: 10.1083/jcb.202302069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 01/04/2024] [Accepted: 02/20/2024] [Indexed: 03/19/2024] Open
Abstract
Cells utilize multiple mechanisms to maintain mitochondrial homeostasis. We recently characterized a pathway that remodels mitochondria in response to metabolic alterations and protein overload stress. This remodeling occurs via the formation of large membranous structures from the mitochondrial outer membrane called mitochondrial-derived compartments (MDCs), which are eventually released from mitochondria and degraded. Here, we conducted a microscopy-based screen in budding yeast to identify factors that regulate MDC formation. We found that two phospholipids, cardiolipin (CL) and phosphatidylethanolamine (PE), differentially regulate MDC biogenesis. CL depletion impairs MDC biogenesis, whereas blocking mitochondrial PE production leads to constitutive MDC formation. Additionally, in response to metabolic MDC activators, cellular and mitochondrial PE declines, and overexpressing mitochondrial PE synthesis enzymes suppress MDC biogenesis. Altogether, our data indicate a requirement for CL in MDC biogenesis and suggest that PE depletion may stimulate MDC formation downstream of MDC-inducing metabolic stress.
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Affiliation(s)
- Tianyao Xiao
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Alyssa M. English
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Zachary N. Wilson
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - J.Alan. Maschek
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integration. Physiology, University of Utah College of Health, Salt Lake City, UT, USA
| | - James E. Cox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
| | - Adam L. Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
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4
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Lewis BM, Cho CY, Her HL, Mizrahi O, Hunter T, Yeo GW. LARP4 is an RNA-binding protein that binds nuclear-encoded mitochondrial mRNAs to promote mitochondrial function. RNA (NEW YORK, N.Y.) 2024; 30:223-239. [PMID: 38164626 PMCID: PMC10870378 DOI: 10.1261/rna.079799.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 11/25/2023] [Indexed: 01/03/2024]
Abstract
Mitochondria-associated RNA-binding proteins (RBPs) have emerged as key contributors to mitochondrial biogenesis and homeostasis. With few examples known, we set out to identify RBPs that regulate nuclear-encoded mitochondrial mRNAs (NEMmRNAs). Our systematic analysis of RNA targets of 150 RBPs identified RBPs with a preference for binding NEMmRNAs, including LARP4, a La RBP family member. We show that LARP4's targets are particularly enriched in mRNAs that encode respiratory chain complex proteins (RCCPs) and mitochondrial ribosome proteins (MRPs) across multiple human cell lines. Through quantitative proteomics, we demonstrate that depletion of LARP4 leads to a significant reduction in RCCP and MRP protein levels. Furthermore, we show that LARP4 depletion reduces mitochondrial function, and that LARP4 re-expression rescues this phenotype. Our findings shed light on a novel function for LARP4 as an RBP that binds to and positively regulates NEMmRNAs to promote mitochondrial respiratory function.
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Affiliation(s)
- Benjamin M Lewis
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92037, USA
- Institute for Genomic Medicine, University of California San Diego, La Jolla, California 92037, USA
- Stem Cell Program, University of California San Diego, La Jolla, California 92037, USA
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Chae Yun Cho
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Hsuan-Lin Her
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92037, USA
- Institute for Genomic Medicine, University of California San Diego, La Jolla, California 92037, USA
- Stem Cell Program, University of California San Diego, La Jolla, California 92037, USA
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, California 92037, USA
| | - Orel Mizrahi
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92037, USA
- Institute for Genomic Medicine, University of California San Diego, La Jolla, California 92037, USA
- Stem Cell Program, University of California San Diego, La Jolla, California 92037, USA
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92037, USA
- Institute for Genomic Medicine, University of California San Diego, La Jolla, California 92037, USA
- Stem Cell Program, University of California San Diego, La Jolla, California 92037, USA
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5
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Hayashi M, Kawarasaki T, Nakatsukasa K. Degradation of citrate synthase lacking the mitochondrial targeting sequence is inhibited in cells defective in Hsp70/Hsp40 chaperones under heat stress conditions. FEMS Yeast Res 2024; 24:foad054. [PMID: 38130235 PMCID: PMC10786195 DOI: 10.1093/femsyr/foad054] [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: 09/29/2023] [Revised: 12/02/2023] [Accepted: 12/20/2023] [Indexed: 12/23/2023] Open
Abstract
Most nucleus-encoded mitochondrial precursor proteins are synthesized in the cytosol and imported into mitochondria in a post-translational manner. In recent years, the quality control mechanisms of nonimported mitochondrial proteins have been intensively studied. In a previous study, we established that in budding yeast a mutant form of citrate synthase 1 (N∆Cit1) that lacks the N-terminal mitochondrial targeting sequence, and therefore mislocalizes to the cytosol is targeted for proteasomal degradation by the SCFUcc1 ubiquitin ligase complex. Here, we show that Hsp70 and Hsp40 chaperones (Ssa1 and Ydj1 in yeast, respectively) are required for N∆Cit1 degradation under heat stress conditions. In the absence of Hsp70 function, a portion of N∆Cit1-GFP formed insoluble aggregates and cytosolic foci. However, the extent of ubiquitination of N∆Cit1 was unaffected, implying that Hsp70/Hsp40 chaperones are involved in the postubiquitination step of N∆Cit1 degradation. Intriguingly, degradation of cytosolic/peroxisomal gluconeogenic citrate synthase (Cit2), an endogenous substrate for SCFUcc1-mediated proteasomal degradation, was not highly dependent on Hsp70 even under heat stress conditions. These results suggest that mitochondrial citrate synthase is thermally vulnerable in the cytosol, where Hsp70/Hsp40 chaperones are required to facilitate its degradation.
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Affiliation(s)
- Mayuko Hayashi
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
| | - Tomoyuki Kawarasaki
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
| | - Kunio Nakatsukasa
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
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6
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Abstract
Perturbation of mitochondrial function can trigger a host of cellular responses that seek to restore cellular metabolism, cytosolic proteostasis, and redox homeostasis. In some cases, these responses persist even after the stress is relieved, leaving the cell or tissue in a less vulnerable state. This process-termed mitohormesis-is increasingly viewed as an important aspect of normal physiology and a critical modulator of various disease processes. Here, we review aspects of mitochondrial stress signaling that, among other things, can rewire the cell's metabolism, activate the integrated stress response, and alter cytosolic quality-control pathways. We also discuss how these pathways are implicated in various disease states from pathogen challenge to chemotherapeutic resistance and how their therapeutic manipulation can lead to new strategies for a host of chronic conditions including aging itself.
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Affiliation(s)
- Yu-Wei Cheng
- Aging Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jie Liu
- Aging Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Toren Finkel
- Aging Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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7
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Rödl S, Herrmann JM. The role of the proteasome in mitochondrial protein quality control. IUBMB Life 2023; 75:868-879. [PMID: 37178401 DOI: 10.1002/iub.2734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/15/2023] [Indexed: 05/15/2023]
Abstract
The abundance of each cellular protein is dynamically adjusted to the prevailing metabolic and stress conditions by modulation of their synthesis and degradation rates. The proteasome represents the major machinery for the degradation of proteins in eukaryotic cells. How the ubiquitin-proteasome system (UPS) controls protein levels and removes superfluous and damaged proteins from the cytosol and the nucleus is well characterized. However, recent studies showed that the proteasome also plays a crucial role in mitochondrial protein quality control. This mitochondria-associated degradation (MAD) thereby acts on two layers: first, the proteasome removes mature, functionally compromised or mis-localized proteins from the mitochondrial surface; and second, the proteasome cleanses the mitochondrial import pore of import intermediates of nascent proteins that are stalled during translocation. In this review, we provide an overview about the components and their specific functions that facilitate proteasomal degradation of mitochondrial proteins in the yeast Saccharomyces cerevisiae. Thereby we explain how the proteasome, in conjunction with a set of intramitochondrial proteases, maintains mitochondrial protein homeostasis and dynamically adapts the levels of mitochondrial proteins to specific conditions.
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Affiliation(s)
- Saskia Rödl
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
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8
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Knöringer K, Groh C, Krämer L, Stein KC, Hansen KG, Zimmermann J, Morgan B, Herrmann JM, Frydman J, Boos F. The unfolded protein response of the endoplasmic reticulum supports mitochondrial biogenesis by buffering nonimported proteins. Mol Biol Cell 2023; 34:ar95. [PMID: 37379206 PMCID: PMC10551703 DOI: 10.1091/mbc.e23-05-0205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/15/2023] [Accepted: 06/22/2023] [Indexed: 06/30/2023] Open
Abstract
Almost all mitochondrial proteins are synthesized in the cytosol and subsequently targeted to mitochondria. The accumulation of nonimported precursor proteins occurring upon mitochondrial dysfunction can challenge cellular protein homeostasis. Here we show that blocking protein translocation into mitochondria results in the accumulation of mitochondrial membrane proteins at the endoplasmic reticulum, thereby triggering the unfolded protein response (UPRER). Moreover, we find that mitochondrial membrane proteins are also routed to the ER under physiological conditions. The level of ER-resident mitochondrial precursors is enhanced by import defects as well as metabolic stimuli that increase the expression of mitochondrial proteins. Under such conditions, the UPRER is crucial to maintain protein homeostasis and cellular fitness. We propose the ER serves as a physiological buffer zone for those mitochondrial precursors that cannot be immediately imported into mitochondria while engaging the UPRER to adjust the ER proteostasis capacity to the extent of precursor accumulation.
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Affiliation(s)
| | - Carina Groh
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Lena Krämer
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Kevin C. Stein
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Katja G. Hansen
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
| | - Jannik Zimmermann
- Institute of Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, 66123 Saarbrücken, Germany
| | - Bruce Morgan
- Institute of Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, 66123 Saarbrücken, Germany
| | | | - Judith Frydman
- Department of Biology, Stanford University, Stanford, CA 94305
- Department of Genetics, Stanford University, Stanford, CA 94305
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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9
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Groh C, Haberkant P, Stein F, Filbeck S, Pfeffer S, Savitski MM, Boos F, Herrmann JM. Mitochondrial dysfunction rapidly modulates the abundance and thermal stability of cellular proteins. Life Sci Alliance 2023; 6:e202201805. [PMID: 36941057 PMCID: PMC10027898 DOI: 10.26508/lsa.202201805] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 03/03/2023] [Accepted: 03/03/2023] [Indexed: 03/23/2023] Open
Abstract
Cellular functionality relies on a well-balanced, but highly dynamic proteome. Dysfunction of mitochondrial protein import leads to the cytosolic accumulation of mitochondrial precursor proteins which compromise cellular proteostasis and trigger a mitoprotein-induced stress response. To dissect the effects of mitochondrial dysfunction on the cellular proteome as a whole, we developed pre-post thermal proteome profiling. This multiplexed time-resolved proteome-wide thermal stability profiling approach with isobaric peptide tags in combination with a pulsed SILAC labelling elucidated dynamic proteostasis changes in several dimensions: In addition to adaptations in protein abundance, we observed rapid modulations of the thermal stability of individual cellular proteins. Different functional groups of proteins showed characteristic response patterns and reacted with group-specific kinetics, allowing the identification of functional modules that are relevant for mitoprotein-induced stress. Thus, our new pre-post thermal proteome profiling approach uncovered a complex response network that orchestrates proteome homeostasis in eukaryotic cells by time-controlled adaptations of the abundance and the conformation of proteins.
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Affiliation(s)
- Carina Groh
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Per Haberkant
- Proteomics Core Facility, EMBL Heidelberg, Heidelberg, Germany
| | - Frank Stein
- Proteomics Core Facility, EMBL Heidelberg, Heidelberg, Germany
| | | | | | | | - Felix Boos
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany;
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10
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Li J, Xu Y, Liu T, Xu Y, Zhao X, Wei J. The Role of Exercise in Maintaining Mitochondrial Proteostasis in Parkinson's Disease. Int J Mol Sci 2023; 24:ijms24097994. [PMID: 37175699 PMCID: PMC10179072 DOI: 10.3390/ijms24097994] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/21/2023] [Accepted: 04/26/2023] [Indexed: 05/15/2023] Open
Abstract
Parkinson's disease (PD) is the second most common rapidly progressive neurodegenerative disease and has serious health and socio-economic consequences. Mitochondrial dysfunction is closely related to the onset and progression of PD, and the use of mitochondria as a target for PD therapy has been gaining traction in terms of both recognition and application. The disruption of mitochondrial proteostasis in the brain tissue of PD patients leads to mitochondrial dysfunction, which manifests as mitochondrial unfolded protein response, mitophagy, and mitochondrial oxidative phosphorylation. Physical exercise is important for the maintenance of human health, and has the great advantage of being a non-pharmacological therapy that is non-toxic, low-cost, and universally applicable. In this review, we investigate the relationships between exercise, mitochondrial proteostasis, and PD and explore the role and mechanisms of mitochondrial proteostasis in delaying PD through exercise.
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Affiliation(s)
- Jingwen Li
- Department of Kinesiology, School of Physical Education, Henan University, Kaifeng 475000, China
- Institute for Brain Sciences Research, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Yanli Xu
- Institute for Brain Sciences Research, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Tingting Liu
- Institute for Brain Sciences Research, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Yuxiang Xu
- Institute for Brain Sciences Research, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Xiantao Zhao
- Department of Kinesiology, School of Physical Education, Henan University, Kaifeng 475000, China
- Institute for Brain Sciences Research, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Jianshe Wei
- Department of Kinesiology, School of Physical Education, Henan University, Kaifeng 475000, China
- Institute for Brain Sciences Research, School of Life Sciences, Henan University, Kaifeng 475004, China
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11
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Nishio K, Kawarasaki T, Sugiura Y, Matsumoto S, Konoshima A, Takano Y, Hayashi M, Okumura F, Kamura T, Mizushima T, Nakatsukasa K. Defective import of mitochondrial metabolic enzyme elicits ectopic metabolic stress. SCIENCE ADVANCES 2023; 9:eadf1956. [PMID: 37058555 PMCID: PMC10104474 DOI: 10.1126/sciadv.adf1956] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 03/16/2023] [Indexed: 06/19/2023]
Abstract
Deficiencies in mitochondrial protein import are associated with a number of diseases. However, although nonimported mitochondrial proteins are at great risk of aggregation, it remains largely unclear how their accumulation causes cell dysfunction. Here, we show that nonimported citrate synthase is targeted for proteasomal degradation by the ubiquitin ligase SCFUcc1. Unexpectedly, our structural and genetic analyses revealed that nonimported citrate synthase appears to form an enzymatically active conformation in the cytosol. Its excess accumulation caused ectopic citrate synthesis, which, in turn, led to an imbalance in carbon flux of sugar, a reduction of the pool of amino acids and nucleotides, and a growth defect. Under these conditions, translation repression is induced and acts as a protective mechanism that mitigates the growth defect. We propose that the consequence of mitochondrial import failure is not limited to proteotoxic insults, but that the accumulation of a nonimported metabolic enzyme elicits ectopic metabolic stress.
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Affiliation(s)
- Kazuya Nishio
- Department of Life Science, Graduate School of Science, University of Hyogo, 2167 Shosha, Himeji 671-2280, Japan
| | - Tomoyuki Kawarasaki
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
| | - Yuki Sugiura
- Department of Biochemistry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
- Multiomics Platform, Center for Cancer Immunotherapy and Immunobiology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Shunsuke Matsumoto
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan
| | - Ayano Konoshima
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
| | - Yuki Takano
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
| | - Mayuko Hayashi
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
| | - Fumihiko Okumura
- Department of Food and Health Sciences, International College of Arts and Sciences, Fukuoka Women’s University, Fukuoka 813-8582, Japan
| | - Takumi Kamura
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Tsunehiro Mizushima
- Department of Life Science, Graduate School of Science, University of Hyogo, 2167 Shosha, Himeji 671-2280, Japan
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Kunio Nakatsukasa
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501, Japan
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12
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Burtscher J, Pepe G, Maharjan N, Riguet N, Di Pardo A, Maglione V, Millet GP. Sphingolipids and impaired hypoxic stress responses in Huntington disease. Prog Lipid Res 2023; 90:101224. [PMID: 36898481 DOI: 10.1016/j.plipres.2023.101224] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/20/2023] [Accepted: 03/05/2023] [Indexed: 03/11/2023]
Abstract
Huntington disease (HD) is a debilitating, currently incurable disease. Protein aggregation and metabolic deficits are pathological hallmarks but their link to neurodegeneration and symptoms remains debated. Here, we summarize alterations in the levels of different sphingolipids in an attempt to characterize sphingolipid patterns specific to HD, an additional molecular hallmark of the disease. Based on the crucial role of sphingolipids in maintaining cellular homeostasis, the dynamic regulation of sphingolipids upon insults and their involvement in cellular stress responses, we hypothesize that maladaptations or blunted adaptations, especially following cellular stress due to reduced oxygen supply (hypoxia) contribute to the development of pathology in HD. We review how sphingolipids shape cellular energy metabolism and control proteostasis and suggest how these functions may fail in HD and in combination with additional insults. Finally, we evaluate the potential of improving cellular resilience in HD by conditioning approaches (improving the efficiency of cellular stress responses) and the role of sphingolipids therein. Sphingolipid metabolism is crucial for cellular homeostasis and for adaptations following cellular stress, including hypoxia. Inadequate cellular management of hypoxic stress likely contributes to HD progression, and sphingolipids are potential mediators. Targeting sphingolipids and the hypoxic stress response are novel treatment strategies for HD.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, 1015 Lausanne, Switzerland; Department of Biomedical Sciences, University of Lausanne, 1005 Lausanne, Switzerland.
| | - Giuseppe Pepe
- IRCCS Neuromed, Via Dell'Elettronica, 86077 Pozzilli, Italy
| | - Niran Maharjan
- Department of Neurology, Center for Experimental Neurology, Inselspital University Hospital, 3010 Bern, Switzerland; Department for Biomedical Research (DBMR), University of Bern, 3010 Bern, Switzerland
| | | | - Alba Di Pardo
- IRCCS Neuromed, Via Dell'Elettronica, 86077 Pozzilli, Italy
| | | | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, 1015 Lausanne, Switzerland; Department of Biomedical Sciences, University of Lausanne, 1005 Lausanne, Switzerland
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13
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The Journey of Mitochondrial Protein Import and the Roadmap to Follow. Int J Mol Sci 2023; 24:ijms24032479. [PMID: 36768800 PMCID: PMC9916854 DOI: 10.3390/ijms24032479] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/19/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023] Open
Abstract
Mitochondria are double membrane-bound organelles that play critical functions in cells including metabolism, energy production, regulation of intrinsic apoptosis, and maintenance of calcium homeostasis. Mitochondria are fascinatingly equipped with their own genome and machinery for transcribing and translating 13 essential proteins of the oxidative phosphorylation system (OXPHOS). The rest of the proteins (99%) that function in mitochondria in the various pathways described above are nuclear-transcribed and synthesized as precursors in the cytosol. These proteins are imported into the mitochondria by the unique mitochondrial protein import system that consists of seven machineries. Proper functioning of the mitochondrial protein import system is crucial for optimal mitochondrial deliverables, as well as mitochondrial and cellular homeostasis. Impaired mitochondrial protein import leads to proteotoxic stress in both mitochondria and cytosol, inducing mitochondrial unfolded protein response (UPRmt). Altered UPRmt is associated with the development of various disease conditions including neurodegenerative and cardiovascular diseases, as well as cancer. This review sheds light on the molecular mechanisms underlying the import of nuclear-encoded mitochondrial proteins, the consequences of defective mitochondrial protein import, and the pathological conditions that arise due to altered UPRmt.
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14
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Krämer L, Dalheimer N, Räschle M, Storchová Z, Pielage J, Boos F, Herrmann JM. MitoStores: chaperone-controlled protein granules store mitochondrial precursors in the cytosol. EMBO J 2023; 42:e112309. [PMID: 36704946 PMCID: PMC10068336 DOI: 10.15252/embj.2022112309] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 01/05/2023] [Accepted: 01/12/2023] [Indexed: 01/28/2023] Open
Abstract
Hundreds of nucleus-encoded mitochondrial precursor proteins are synthesized in the cytosol and imported into mitochondria in a post-translational manner. However, the early processes associated with mitochondrial protein targeting remain poorly understood. Here, we show that in Saccharomyces cerevisiae, the cytosol has the capacity to transiently store mitochondrial matrix-destined precursors in dedicated deposits that we termed MitoStores. Competitive inhibition of mitochondrial protein import via clogging of import sites greatly enhances the formation of MitoStores, but they also form during physiological cell growth on nonfermentable carbon sources. MitoStores are enriched for a specific subset of nucleus-encoded mitochondrial proteins, in particular those containing N-terminal mitochondrial targeting sequences. Our results suggest that MitoStore formation suppresses the toxic potential of aberrantly accumulating mitochondrial precursor proteins and is controlled by the heat shock proteins Hsp42 and Hsp104. Thus, the cytosolic protein quality control system plays an active role during the early stages of mitochondrial protein targeting through the coordinated and localized sequestration of mitochondrial precursor proteins.
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Affiliation(s)
- Lena Krämer
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Niko Dalheimer
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Markus Räschle
- Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Zuzana Storchová
- Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Jan Pielage
- Zoology and Neurobiology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
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15
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Burtscher J, Soltany A, Visavadiya NP, Burtscher M, Millet GP, Khoramipour K, Khamoui AV. Mitochondrial stress and mitokines in aging. Aging Cell 2023; 22:e13770. [PMID: 36642986 PMCID: PMC9924952 DOI: 10.1111/acel.13770] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/08/2022] [Accepted: 12/20/2022] [Indexed: 01/17/2023] Open
Abstract
Mitokines are signaling molecules that enable communication of local mitochondrial stress to other mitochondria in distant cells and tissues. Among those molecules are FGF21, GDF15 (both expressed in the nucleus) and several mitochondrial-derived peptides, including humanin. Their responsiveness to mitochondrial stress induces mitokine-signaling in response for example to exercise, following mitochondrial challenges in skeletal muscle. Such signaling is emerging as an important mediator of exercise-derived and dietary strategy-related molecular and systemic health benefits, including healthy aging. A compensatory increase in mitokine synthesis and secretion could preserve mitochondrial function and overall cellular vitality. Conversely, resistance against mitokine actions may also develop. Alterations of mitokine-levels, and therefore of mitokine-related inter-tissue cross talk, are associated with general aging processes and could influence the development of age-related chronic metabolic, cardiovascular and neurological diseases; whether these changes contribute to aging or represent "rescue factors" remains to be conclusively shown. The aim of the present review is to summarize the expanding knowledge on mitokines, the potential to modulate them by lifestyle and their involvement in aging and age-related diseases. We highlight the importance of well-balanced mitokine-levels, the preventive and therapeutic properties of maintaining mitokine homeostasis and sensitivity of mitokine signaling but also the risks arising from the dysregulation of mitokines. While reduced mitokine levels may impair inter-organ crosstalk, also excessive mitokine concentrations can have deleterious consequences and are associated with conditions such as cancer and heart failure. Preservation of healthy mitokine signaling levels can be achieved by regular exercise and is associated with an increased lifespan.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport SciencesUniversity of LausanneLausanneSwitzerland,Department of Biomedical SciencesUniversity of LausanneLausanneSwitzerland
| | - Afsaneh Soltany
- Department of Biology, Faculty of ScienceUniversity of ShirazShirazIran
| | - Nishant P. Visavadiya
- Department of Exercise Science and Health PromotionFlorida Atlantic UniversityBoca RatonFloridaUSA
| | - Martin Burtscher
- Department of Sport ScienceUniversity of InnsbruckInnsbruckAustria
| | - Grégoire P. Millet
- Institute of Sport SciencesUniversity of LausanneLausanneSwitzerland,Department of Biomedical SciencesUniversity of LausanneLausanneSwitzerland
| | - Kayvan Khoramipour
- Department of Physiology and Pharmacology, Neuroscience Research Center, Institute of Neuropharmacology, and Afzalipour School of MedicineKerman University of Medical SciencesKermanIran
| | - Andy V. Khamoui
- Department of Exercise Science and Health PromotionFlorida Atlantic UniversityBoca RatonFloridaUSA
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16
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Gao LL, Hong ZH, Wang Y, Wu GZ. Chloroplast proteostasis: A story of birth, life, and death. PLANT COMMUNICATIONS 2023; 4:100424. [PMID: 35964157 PMCID: PMC9860172 DOI: 10.1016/j.xplc.2022.100424] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/02/2022] [Accepted: 08/10/2022] [Indexed: 06/02/2023]
Abstract
Protein homeostasis (proteostasis) is a dynamic balance of protein synthesis and degradation. Because of the endosymbiotic origin of chloroplasts and the massive transfer of their genetic information to the nucleus of the host cell, many protein complexes in the chloroplasts are constituted from subunits encoded by both genomes. Hence, the proper function of chloroplasts relies on the coordinated expression of chloroplast- and nucleus-encoded genes. The biogenesis and maintenance of chloroplast proteostasis are dependent on synthesis of chloroplast-encoded proteins, import of nucleus-encoded chloroplast proteins from the cytosol, and clearance of damaged or otherwise undesired "old" proteins. This review focuses on the regulation of chloroplast proteostasis, its interaction with proteostasis of the cytosol, and its retrograde control over nuclear gene expression. We also discuss significant issues and perspectives for future studies and potential applications for improving the photosynthetic performance and stress tolerance of crops.
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Affiliation(s)
- Lin-Lin Gao
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Zheng-Hui Hong
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yinsong Wang
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Guo-Zhang Wu
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
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17
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Zhou Z, Fan Y, Zong R, Tan K. The mitochondrial unfolded protein response: A multitasking giant in the fight against human diseases. Ageing Res Rev 2022; 81:101702. [PMID: 35908669 DOI: 10.1016/j.arr.2022.101702] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 07/15/2022] [Accepted: 07/26/2022] [Indexed: 02/06/2023]
Abstract
Mitochondria, which serve as the energy factories of cells, are involved in cell differentiation, calcium homeostasis, amino acid and fatty acid metabolism and apoptosis. In response to environmental stresses, mitochondrial homeostasis is regulated at both the organelle and molecular levels to effectively maintain the number and function of mitochondria. The mitochondrial unfolded protein response (UPRmt) is an adaptive intracellular stress mechanism that responds to stress signals by promoting the transcription of genes encoding mitochondrial chaperones and proteases. The mechanism of the UPRmt in Caenorhabditis elegans (C. elegans) has been clarified over time, and the main regulatory factors include ATFS-1, UBL-5 and DVE-1. In mammals, the activation of the UPRmt involves eIF2α phosphorylation and the uORF-regulated expression of CHOP, ATF4 and ATF5. Several additional factors, such as SIRT3 and HSF1, are also involved in regulating the UPRmt. A deep and comprehensive exploration of the UPRmt can provide new directions and strategies for the treatment of human diseases, including aging, neurodegenerative diseases, cardiovascular diseases and diabetes. In this review, we mainly discuss the function of UPRmt, describe the regulatory mechanisms of UPRmt in C. elegans and mammals, and summarize the relationship between UPRmt and various human diseases.
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Affiliation(s)
- Zixin Zhou
- Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Province Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China; State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Beijing, China
| | - Yumei Fan
- Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Province Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China
| | - Ruikai Zong
- Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Province Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China
| | - Ke Tan
- Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Province Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China.
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18
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Liu S, Liu S, Jiang H. Multifaceted roles of mitochondrial stress responses under ETC dysfunction - repair, destruction and pathogenesis. FEBS J 2022; 289:6994-7013. [PMID: 34918460 DOI: 10.1111/febs.16323] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/08/2021] [Accepted: 12/15/2021] [Indexed: 01/13/2023]
Abstract
Electron transport chain (ETC) dysfunction is a common feature of mitochondrial diseases and induces severe cellular stresses, including mitochondrial membrane potential (Δψm ) reduction, mitochondrial matrix acidification, metabolic derangements and proteostatic stresses. Extensive studies of ETC dysfunction in yeast, Caenorhabditis elegans, cultured cells and mouse models have revealed multiple mitochondrial stress response pathways. Here, we summarise the current understanding of the triggers, sensors, signalling mechanisms and the functional outcomes of mitochondrial stress responses in different species. We highlight Δψm reduction as a major trigger of stress responses in different species, but the responses are species-specific and the outcomes are context-dependent. ETC dysfunction elicits a mitochondrial unfolded protein response (UPRmt ) to repair damaged mitochondria in C. elegans, and activates a global adaptive programme to maintain Δψm in yeast. Yeast and C. elegans responses are remarkably similar at the downstream responses, although they are activated by different signalling mechanisms. UPRmt generally protects ETC-defective worms, but its constitutive activation is toxic for wildtype worms and worms carrying mutant mtDNA. In contrast to lower organisms, ETC dysfunction in mammals mainly activates a mitochondrial integrated stress response (ISRmt ) to reprogramme metabolism and a PINK1-Parkin mitophagy pathway to degrade damaged mitochondria. Accumulating in vivo results suggest that the ATF4 branch of ISRmt exacerbates metabolic derangements to accelerate mitochondrial disease progression. The in vivo roles of mitophagy in mitochondrial diseases are also context-dependent. These results thus reveal the common and unique aspects of mitochondrial stress responses in different species and highlight their multifaceted roles in mitochondrial diseases.
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Affiliation(s)
- Shanshan Liu
- National Institute of Biological Sciences, Beijing, China.,Beijing Key Laboratory of Cell Biology for Animal Aging, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
| | - Siqi Liu
- National Institute of Biological Sciences, Beijing, China.,Beijing Key Laboratory of Cell Biology for Animal Aging, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
| | - Hui Jiang
- National Institute of Biological Sciences, Beijing, China.,Beijing Key Laboratory of Cell Biology for Animal Aging, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
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19
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Savu DI, Moisoi N. Mitochondria - Nucleus communication in neurodegenerative disease. Who talks first, who talks louder? BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148588. [PMID: 35780856 DOI: 10.1016/j.bbabio.2022.148588] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 06/09/2022] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Abstract
Mitochondria - nuclear coadaptation has been central to eukaryotic evolution. The dynamic dialogue between the two compartments within the context of multiorganellar interactions is critical for maintaining cellular homeostasis and directing the balance survival-death in case of cellular stress. The conceptualisation of mitochondria - nucleus communication has so far been focused on the communication from the mitochondria under stress to the nucleus and the consequent signalling responses, as well as from the nucleus to mitochondria in the context of DNA damage and repair. During ageing processes this dialogue may be better viewed as an integrated bidirectional 'talk' with feedback loops that expand beyond these two organelles depending on physiological cues. Here we explore the current views on mitochondria - nucleus dialogue and its role in maintaining cellular health with a focus on brain cells and neurodegenerative disease. Thus, we detail the transcriptional responses initiated by mitochondrial dysfunction in order to protect itself and the general cellular homeostasis. Additionally, we are reviewing the knowledge of the stress pathways initiated by DNA damage which affect mitochondria homeostasis and we add the information provided by the study of combined mitochondrial and genotoxic damage. Finally, we reflect on how each organelle may take the lead in this dialogue in an ageing context where both compartments undergo accumulation of stress and damage and where, perhaps, even the communications' mechanisms may suffer interruptions.
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Affiliation(s)
- Diana Iulia Savu
- Department of Life and Environmental Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering, Reactorului 30, P.O. Box MG-6, Magurele 077125, Romania
| | - Nicoleta Moisoi
- Leicester School of Pharmacy, Leicester Institute for Pharmaceutical Innovation, Faculty of Health Sciences, De Montfort University, The Gateway, Hawthorn Building 1.03, LE1 9BH Leicester, UK.
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20
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Remission of obesity and insulin resistance is not sufficient to restore mitochondrial homeostasis in visceral adipose tissue. Redox Biol 2022; 54:102353. [PMID: 35777200 PMCID: PMC9287736 DOI: 10.1016/j.redox.2022.102353] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/20/2022] [Accepted: 05/24/2022] [Indexed: 11/21/2022] Open
Abstract
Metabolic plasticity is the ability of a biological system to adapt its metabolic phenotype to different environmental stressors. We used a whole-body and tissue-specific phenotypic, functional, proteomic, metabolomic and transcriptomic approach to systematically assess metabolic plasticity in diet-induced obese mice after a combined nutritional and exercise intervention. Although most obesity and overnutrition-related pathological features were successfully reverted, we observed a high degree of metabolic dysfunction in visceral white adipose tissue, characterized by abnormal mitochondrial morphology and functionality. Despite two sequential therapeutic interventions and an apparent global healthy phenotype, obesity triggered a cascade of events in visceral adipose tissue progressing from mitochondrial metabolic and proteostatic alterations to widespread cellular stress, which compromises its biosynthetic and recycling capacity. In humans, weight loss after bariatric surgery showed a transcriptional signature in visceral adipose tissue similar to our mouse model of obesity reversion. Overall, our data indicate that obesity prompts a lasting metabolic fingerprint that leads to a progressive breakdown of metabolic plasticity in visceral adipose tissue.
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21
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Killackey SA, Bi Y, Soares F, Hammi I, Winsor NJ, Abdul-Sater AA, Philpott DJ, Arnoult D, Girardin SE. Mitochondrial protein import stress regulates the LC3 lipidation step of mitophagy through NLRX1 and RRBP1. Mol Cell 2022; 82:2815-2831.e5. [PMID: 35752171 DOI: 10.1016/j.molcel.2022.06.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 04/26/2022] [Accepted: 06/01/2022] [Indexed: 12/26/2022]
Abstract
Protein import into mitochondria is a highly regulated process, yet how cells clear mitochondria undergoing dysfunctional protein import remains poorly characterized. Here we showed that mitochondrial protein import stress (MPIS) triggers localized LC3 lipidation. This arm of the mitophagy pathway occurs through the Nod-like receptor (NLR) protein NLRX1 while, surprisingly, without the engagement of the canonical mitophagy protein PINK1. Mitochondrial depolarization, which itself induces MPIS, also required NLRX1 for LC3 lipidation. While normally targeted to the mitochondrial matrix, cytosol-retained NLRX1 recruited RRBP1, a ribosome-binding transmembrane protein of the endoplasmic reticulum, which relocated to the mitochondrial vicinity during MPIS, and the NLRX1/RRBP1 complex in turn controlled the recruitment and lipidation of LC3. Furthermore, NLRX1 controlled skeletal muscle mitophagy in vivo and regulated endurance capacity during exercise. Thus, localization and lipidation of LC3 at the site of mitophagosome formation is a regulated step of mitophagy controlled by NLRX1/RRBP1 in response to MPIS.
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Affiliation(s)
- Samuel A Killackey
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Yuntian Bi
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Fraser Soares
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 2C1, Canada
| | - Ikram Hammi
- INSERM U1197, Hôpital Paul Brousse, Bâtiment Lavoisier, 94807 Villejuif Cedex, France
| | - Nathaniel J Winsor
- Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ali A Abdul-Sater
- School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), Faculty of Health, York University, Toronto, ON M3J 1P3, Canada
| | - Dana J Philpott
- Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Damien Arnoult
- INSERM U1197, Hôpital Paul Brousse, Bâtiment Lavoisier, 94807 Villejuif Cedex, France
| | - Stephen E Girardin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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22
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Dewar CE, Oeljeklaus S, Mani J, Mühlhäuser WWD, von Känel C, Zimmermann J, Ochsenreiter T, Warscheid B, Schneider A. Mistargeting of aggregation prone mitochondrial proteins activates a nucleus-mediated posttranscriptional quality control pathway in trypanosomes. Nat Commun 2022; 13:3084. [PMID: 35654893 PMCID: PMC9163028 DOI: 10.1038/s41467-022-30748-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 05/02/2022] [Indexed: 12/25/2022] Open
Abstract
Mitochondrial protein import in the parasitic protozoan Trypanosoma brucei is mediated by the atypical outer membrane translocase, ATOM. It consists of seven subunits including ATOM69, the import receptor for hydrophobic proteins. Ablation of ATOM69, but not of any other subunit, triggers a unique quality control pathway resulting in the proteasomal degradation of non-imported mitochondrial proteins. The process requires a protein of unknown function, an E3 ubiquitin ligase and the ubiquitin-like protein (TbUbL1), which all are recruited to the mitochondrion upon ATOM69 depletion. TbUbL1 is a nuclear protein, a fraction of which is released to the cytosol upon triggering of the pathway. Nuclear release is essential as cytosolic TbUbL1 can bind mislocalised mitochondrial proteins and likely transfers them to the proteasome. Mitochondrial quality control has previously been studied in yeast and metazoans. Finding such a pathway in the highly diverged trypanosomes suggests such pathways are an obligate feature of all eukaryotes. Mitochondria import most of their proteins posttranslationally. Here, Dewar et al. characterize the mitochondrial quality control mechanism of Trypanosoma brucei. Through proteomics and functional studies, they show that only ablation of ATOM69, one of the seven subunits of its mitochondrial protein translocase, triggers a unique quality control pathway resulting in TbUbL1 release from the nucleus and subsequent proteasomal degradation of non-imported mitochondrial proteins.
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Affiliation(s)
- Caroline E Dewar
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland
| | - Silke Oeljeklaus
- Faculty of Chemistry and Pharmacy, Department of Biochemistry, Theodor Boveri-Institute, University of Würzburg, 97074, Würzburg, Germany.,Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Jan Mani
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland
| | - Wignand W D Mühlhäuser
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Corinne von Känel
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland
| | - Johannes Zimmermann
- Faculty of Chemistry and Pharmacy, Department of Biochemistry, Theodor Boveri-Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Torsten Ochsenreiter
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Bern, CH-3012, Switzerland
| | - Bettina Warscheid
- Faculty of Chemistry and Pharmacy, Department of Biochemistry, Theodor Boveri-Institute, University of Würzburg, 97074, Würzburg, Germany. .,Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany. .,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany.
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland.
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23
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Sing TL, Conlon K, Lu SH, Madrazo N, Morse K, Barker JC, Hollerer I, Brar GA, Sudmant PH, Ünal E. Meiotic cDNA libraries reveal gene truncations and mitochondrial proteins important for competitive fitness in Saccharomyces cerevisiae. Genetics 2022; 221:iyac066. [PMID: 35471663 PMCID: PMC9157139 DOI: 10.1093/genetics/iyac066] [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: 08/16/2021] [Accepted: 04/13/2022] [Indexed: 01/16/2023] Open
Abstract
Gametogenesis is an evolutionarily conserved developmental program whereby a diploid progenitor cell undergoes meiosis and cellular remodeling to differentiate into haploid gametes, the precursors for sexual reproduction. Even in the simple eukaryotic organism Saccharomyces cerevisiae, the meiotic transcriptome is very rich and complex, thereby necessitating new tools for functional studies. Here, we report the construction of 5 stage-specific, inducible complementary DNA libraries from meiotic cells that represent over 84% of the genes found in the budding yeast genome. We employed computational strategies to detect endogenous meiotic transcript isoforms as well as library-specific gene truncations. Furthermore, we developed a robust screening pipeline to test the effect of each complementary DNA on competitive fitness. Our multiday proof-of-principle time course revealed 877 complementary DNAs that were detrimental for competitive fitness when overexpressed. The list included mitochondrial proteins that cause dose-dependent disruption of cellular respiration as well as library-specific gene truncations that expose a dominant negative effect on competitive growth. Together, these high-quality complementary DNA libraries provide an important tool for systematically identifying meiotic genes, transcript isoforms, and protein domains that are important for a specific biological function.
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Affiliation(s)
- Tina L Sing
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Katie Conlon
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Stephanie H Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Nicole Madrazo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Kaitlin Morse
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Juliet C Barker
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Ina Hollerer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Gloria A Brar
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Peter H Sudmant
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Elçin Ünal
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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24
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Samluk L, Ostapczuk P, Dziembowska M. Long-term mitochondrial stress induces early steps of Tau aggregation by increasing reactive oxygen species levels and affecting cellular proteostasis. Mol Biol Cell 2022; 33:ar67. [PMID: 35446108 PMCID: PMC9635289 DOI: 10.1091/mbc.e21-11-0553] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Accumulating evidence indicates that mitochondrial dysfunction is involved in the pathogenesis of neurodegenerative diseases. Both of these conditions are often associated with an increase in protein aggregation. However, still unknown are the specific defects of mitochondrial biology that play a critical role in the development of Alzheimer’s disease, in which Tau protein aggregates are observed in the brains of some patients. Here, we report that long-term mitochondrial stress triggered Tau dimerization, which is the first step of protein aggregation. Mitochondrial dysfunction was induced in HEK293T cells that received prolonged treatment with rotenone and in HEK293T cells with the knockout of NDUFA11 protein. To monitor changes in Tau protein aggregation, we took advantage of the bimolecular fluorescence complementation assay using HEK293T cells that were transfected with plasmids that encoded Tau. Inhibition of the ISR with ISRIB induced Tau dimerization, whereas ISR activation with salubrinal, guanabenz, and sephin1 partially reversed this process. Cells that were treated with ROS scavengers, N-acetyl-l-cysteine or MitoQ, significantly reduced the amount of ROS and Tau dimerization, indicating the involvement of oxidative stress in Tau aggregation. Our results indicate that long-term mitochondrial stress may induce early steps of Tau protein aggregation by affecting oxidative balance and cellular proteostasis.
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Affiliation(s)
- Lukasz Samluk
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
| | - Piotr Ostapczuk
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
| | - Magdalena Dziembowska
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
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25
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Sayles NM, Southwell N, McAvoy K, Kim K, Pesini A, Anderson CJ, Quinzii C, Cloonan S, Kawamata H, Manfredi G. Mutant CHCHD10 causes an extensive metabolic rewiring that precedes OXPHOS dysfunction in a murine model of mitochondrial cardiomyopathy. Cell Rep 2022; 38:110475. [PMID: 35263592 PMCID: PMC9013208 DOI: 10.1016/j.celrep.2022.110475] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 11/01/2021] [Accepted: 02/10/2022] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial cardiomyopathies are fatal diseases, with no effective treatment. Alterations of heart mitochondrial function activate the mitochondrial integrated stress response (ISRmt), a transcriptional program affecting cell metabolism, mitochondrial biogenesis, and proteostasis. In humans, mutations in CHCHD10, a mitochondrial protein with unknown function, were recently associated with dominant multi-system mitochondrial diseases, whose pathogenic mechanisms remain to be elucidated. Here, in CHCHD10 knockin mutant mice, we identify an extensive cardiac metabolic rewiring triggered by proteotoxic ISRmt. The stress response arises early on, before the onset of bioenergetic impairments, triggering a switch from oxidative to glycolytic metabolism, enhancement of transsulfuration and one carbon (1C) metabolism, and widespread metabolic imbalance. In parallel, increased NADPH oxidases elicit antioxidant responses, leading to heme depletion. As the disease progresses, the adaptive metabolic stress response fails, resulting in fatal cardiomyopathy. Our findings suggest that early interventions to counteract metabolic imbalance could ameliorate mitochondrial cardiomyopathy associated with proteotoxic ISRmt. Sayles et al. report that mutant CHCHD10 proteotoxicity activates the mitochondrial integrated stress response (ISRmt) in a mouse model of mitochondrial cardiomyopathy. Chronic ISRmt causes profound metabolic imbalances, culminating in oxidative stress and iron dysregulation, ultimately resulting in mitochondrial dysfunction and contributing to disease pathogenesis.
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Affiliation(s)
- Nicole M Sayles
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA; Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, 1300 York Avenue, New York, NY 10065, USA
| | - Nneka Southwell
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA; Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, 1300 York Avenue, New York, NY 10065, USA
| | - Kevin McAvoy
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
| | - Kihwan Kim
- Department of Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Alba Pesini
- Department of Neurology, Columbia University, 710 West 168th Street, New York, NY 10032, USA
| | - Corey J Anderson
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
| | - Catarina Quinzii
- Department of Neurology, Columbia University, 710 West 168th Street, New York, NY 10032, USA
| | - Suzanne Cloonan
- Department of Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA; The School of Medicine, Trinity Biomedical Science Institute, Trinity College Dublin, Pearse St, Dublin 2 52-160, Ireland; Tallaght University Hospital, Tallaght, Dublin 24 D24 NR0A, Ireland
| | - Hibiki Kawamata
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
| | - Giovanni Manfredi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA.
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26
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Mitochondrial protein import determines lifespan through metabolic reprogramming and de novo serine biosynthesis. Nat Commun 2022; 13:651. [PMID: 35115503 PMCID: PMC8814026 DOI: 10.1038/s41467-022-28272-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 01/13/2022] [Indexed: 02/04/2023] Open
Abstract
Sustained mitochondrial fitness relies on coordinated biogenesis and clearance. Both processes are regulated by constant targeting of proteins into the organelle. Thus, mitochondrial protein import sets the pace for mitochondrial abundance and function. However, our understanding of mitochondrial protein translocation as a regulator of longevity remains enigmatic. Here, we targeted the main protein import translocases and assessed their contribution to mitochondrial abundance and organismal physiology. We find that reduction in cellular mitochondrial load through mitochondrial protein import system suppression, referred to as MitoMISS, elicits a distinct longevity paradigm. We show that MitoMISS triggers the mitochondrial unfolded protein response, orchestrating an adaptive reprogramming of metabolism. Glycolysis and de novo serine biosynthesis are causatively linked to longevity, whilst mitochondrial chaperone induction is dispensable for lifespan extension. Our findings extent the pro-longevity role of UPRmt and provide insight, relevant to the metabolic alterations that promote or undermine survival and longevity. Mitochondrial function is linked to lifespan. Here the authors show that inhibition of mitochondrial protein import leads to a reduction in mitochondrial abundance and extends lifespan in Caenorhabditis elegans via activation of glycolysis and de novo serine biosynthesis.
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27
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Hémono M, Haller A, Chicher J, Duchêne AM, Ngondo RP. The interactome of CLUH reveals its association to SPAG5 and its co-translational proximity to mitochondrial proteins. BMC Biol 2022; 20:13. [PMID: 35012549 PMCID: PMC8744257 DOI: 10.1186/s12915-021-01213-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 12/14/2021] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Mitochondria require thousands of proteins to fulfill their essential function in energy production and other fundamental biological processes. These proteins are mostly encoded by the nuclear genome, translated in the cytoplasm before being imported into the organelle. RNA binding proteins (RBPs) are central players in the regulation of this process by affecting mRNA translation, stability, or localization. CLUH is an RBP recognizing specifically mRNAs coding for mitochondrial proteins, but its precise molecular function and interacting partners remain undiscovered in mammals. RESULTS Here we reveal for the first time CLUH interactome in mammalian cells. Using both co-IP and BioID proximity-labeling approaches, we identify novel molecular partners interacting stably or transiently with CLUH in HCT116 cells and mouse embryonic stem cells. We reveal stable RNA-independent interactions of CLUH with itself and with SPAG5 in cytosolic granular structures. More importantly, we uncover an unexpected proximity of CLUH to mitochondrial proteins and their cognate mRNAs in the cytosol. We show that this interaction occurs during the process of active translation and is dependent on CLUH TPR domain. CONCLUSIONS Overall, through the analysis of CLUH interactome, our study sheds a new light on CLUH molecular function by revealing new partners and by highlighting its link to the translation and subcellular localization of some mRNAs coding for mitochondrial proteins.
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Affiliation(s)
- Mickaële Hémono
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du Général Zimmer, Strasbourg, 67084, France
| | - Alexandre Haller
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du Général Zimmer, Strasbourg, 67084, France
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), UMR 7104, U 1258, 1 rue Laurent Fries, 67404, Illkirch, France
| | - Johana Chicher
- Plateforme protéomique Strasbourg Esplanade FR1589 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Anne-Marie Duchêne
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du Général Zimmer, Strasbourg, 67084, France
| | - Richard Patryk Ngondo
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du Général Zimmer, Strasbourg, 67084, France.
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28
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Cytosolic Quality Control of Mitochondrial Protein Precursors-The Early Stages of the Organelle Biogenesis. Int J Mol Sci 2021; 23:ijms23010007. [PMID: 35008433 PMCID: PMC8745001 DOI: 10.3390/ijms23010007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/12/2022] Open
Abstract
With few exceptions, proteins that constitute the proteome of mitochondria originate outside of this organelle in precursor forms. Such protein precursors follow dedicated transportation paths to reach specific parts of mitochondria, where they complete their maturation and perform their functions. Mitochondrial precursor targeting and import pathways are essential to maintain proper mitochondrial function and cell survival, thus are tightly controlled at each stage. Mechanisms that sustain protein homeostasis of the cytosol play a vital role in the quality control of proteins targeted to the organelle. Starting from their synthesis, precursors are constantly chaperoned and guided to reduce the risk of premature folding, erroneous interactions, or protein damage. The ubiquitin-proteasome system provides proteolytic control that is not restricted to defective proteins but also regulates the supply of precursors to the organelle. Recent discoveries provide evidence that stress caused by the mislocalization of mitochondrial proteins may contribute to disease development. Precursors are not only subject to regulation but also modulate cytosolic machinery. Here we provide an overview of the cellular pathways that are involved in precursor maintenance and guidance at the early cytosolic stages of mitochondrial biogenesis. Moreover, we follow the circumstances in which mitochondrial protein import deregulation disturbs the cellular balance, carefully looking for rescue paths that can restore proteostasis.
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29
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Lisci M, Barton PR, Randzavola LO, Ma CY, Marchingo JM, Cantrell DA, Paupe V, Prudent J, Stinchcombe JC, Griffiths GM. Mitochondrial translation is required for sustained killing by cytotoxic T cells. Science 2021; 374:eabe9977. [PMID: 34648346 DOI: 10.1126/science.abe9977] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Miriam Lisci
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
| | - Philippa R Barton
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
| | - Lyra O Randzavola
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
| | - Claire Y Ma
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
| | - Julia M Marchingo
- Cell Signalling and Immunology Division, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Doreen A Cantrell
- Cell Signalling and Immunology Division, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Vincent Paupe
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
| | - Julien Prudent
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
| | - Jane C Stinchcombe
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
| | - Gillian M Griffiths
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, CB2 0XY, UK
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30
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Nowicka U, Chroscicki P, Stroobants K, Sladowska M, Turek M, Uszczynska-Ratajczak B, Kundra R, Goral T, Perni M, Dobson CM, Vendruscolo M, Chacinska A. Cytosolic aggregation of mitochondrial proteins disrupts cellular homeostasis by stimulating the aggregation of other proteins. eLife 2021; 10:65484. [PMID: 34292154 PMCID: PMC8457837 DOI: 10.7554/elife.65484] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
Mitochondria are organelles with their own genomes, but they rely on the import of nuclear-encoded proteins that are translated by cytosolic ribosomes. Therefore, it is important to understand whether failures in the mitochondrial uptake of these nuclear-encoded proteins can cause proteotoxic stress and identify response mechanisms that may counteract it. Here, we report that upon impairments in mitochondrial protein import, high-risk precursor and immature forms of mitochondrial proteins form aberrant deposits in the cytosol. These deposits then cause further cytosolic accumulation and consequently aggregation of other mitochondrial proteins and disease-related proteins, including α-synuclein and amyloid β. This aggregation triggers a cytosolic protein homeostasis imbalance that is accompanied by specific molecular chaperone responses at both the transcriptomic and protein levels. Altogether, our results provide evidence that mitochondrial dysfunction, specifically protein import defects, contributes to impairments in protein homeostasis, thus revealing a possible molecular mechanism by which mitochondria are involved in neurodegenerative diseases.
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Affiliation(s)
- Urszula Nowicka
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Piotr Chroscicki
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Karen Stroobants
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Maria Sladowska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Michal Turek
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | | | - Rishika Kundra
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Tomasz Goral
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Michele Perni
- Chemistry, University of Cambridge, Cambridge, United Kingdom
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31
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Sensing, signaling and surviving mitochondrial stress. Cell Mol Life Sci 2021; 78:5925-5951. [PMID: 34228161 PMCID: PMC8316193 DOI: 10.1007/s00018-021-03887-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 06/15/2021] [Accepted: 06/22/2021] [Indexed: 12/11/2022]
Abstract
Mitochondrial fidelity is a key determinant of longevity and was found to be perturbed in a multitude of disease contexts ranging from neurodegeneration to heart failure. Tight homeostatic control of the mitochondrial proteome is a crucial aspect of mitochondrial function, which is severely complicated by the evolutionary origin and resulting peculiarities of the organelle. This is, on one hand, reflected by a range of basal quality control factors such as mitochondria-resident chaperones and proteases, that assist in import and folding of precursors as well as removal of aggregated proteins. On the other hand, stress causes the activation of several additional mechanisms that counteract any damage that may threaten mitochondrial function. Countermeasures depend on the location and intensity of the stress and on a range of factors that are equipped to sense and signal the nature of the encountered perturbation. Defective mitochondrial import activates mechanisms that combat the accumulation of precursors in the cytosol and the import pore. To resolve proteotoxic stress in the organelle interior, mitochondria depend on nuclear transcriptional programs, such as the mitochondrial unfolded protein response and the integrated stress response. If organelle damage is too severe, mitochondria signal for their own destruction in a process termed mitophagy, thereby preventing further harm to the mitochondrial network and allowing the cell to salvage their biological building blocks. Here, we provide an overview of how different types and intensities of stress activate distinct pathways aimed at preserving mitochondrial fidelity.
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32
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Schlagowski AM, Knöringer K, Morlot S, Sánchez Vicente A, Flohr T, Krämer L, Boos F, Khalid N, Ahmed S, Schramm J, Murschall LM, Haberkant P, Stein F, Riemer J, Westermann B, Braun RJ, Winklhofer KF, Charvin G, Herrmann JM. Increased levels of mitochondrial import factor Mia40 prevent the aggregation of polyQ proteins in the cytosol. EMBO J 2021; 40:e107913. [PMID: 34191328 PMCID: PMC8365258 DOI: 10.15252/embj.2021107913] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 05/25/2021] [Accepted: 05/31/2021] [Indexed: 12/11/2022] Open
Abstract
The formation of protein aggregates is a hallmark of neurodegenerative diseases. Observations on patient samples and model systems demonstrated links between aggregate formation and declining mitochondrial functionality, but causalities remain unclear. We used Saccharomyces cerevisiae to analyze how mitochondrial processes regulate the behavior of aggregation‐prone polyQ protein derived from human huntingtin. Expression of Q97‐GFP rapidly led to insoluble cytosolic aggregates and cell death. Although aggregation impaired mitochondrial respiration only slightly, it considerably interfered with the import of mitochondrial precursor proteins. Mutants in the import component Mia40 were hypersensitive to Q97‐GFP, whereas Mia40 overexpression strongly suppressed the formation of toxic Q97‐GFP aggregates both in yeast and in human cells. Based on these observations, we propose that the post‐translational import of mitochondrial precursor proteins into mitochondria competes with aggregation‐prone cytosolic proteins for chaperones and proteasome capacity. Mia40 regulates this competition as it has a rate‐limiting role in mitochondrial protein import. Therefore, Mia40 is a dynamic regulator in mitochondrial biogenesis that can be exploited to stabilize cytosolic proteostasis.
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Affiliation(s)
| | | | - Sandrine Morlot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Ana Sánchez Vicente
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Tamara Flohr
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Lena Krämer
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Nabeel Khalid
- German Research Center for Artificial Intelligence DFKI, Kaiserslautern, Germany
| | - Sheraz Ahmed
- German Research Center for Artificial Intelligence DFKI, Kaiserslautern, Germany
| | - Jana Schramm
- Cell Biology, University of Bayreuth, Bayreuth, Germany
| | | | - Per Haberkant
- Proteomics Core Facility, EMBL Heidelberg, Heidelberg, Germany
| | - Frank Stein
- Proteomics Core Facility, EMBL Heidelberg, Heidelberg, Germany
| | - Jan Riemer
- Biochemistry, University of Cologne, Cologne, Germany
| | | | - Ralf J Braun
- Cell Biology, University of Bayreuth, Bayreuth, Germany.,Neurodegeneration, Danube Private University, Krems/Donau, Austria
| | - Konstanze F Winklhofer
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Gilles Charvin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
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33
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James R, Chaytow H, Ledahawsky LM, Gillingwater TH. Revisiting the role of mitochondria in spinal muscular atrophy. Cell Mol Life Sci 2021; 78:4785-4804. [PMID: 33821292 PMCID: PMC8195803 DOI: 10.1007/s00018-021-03819-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/22/2021] [Accepted: 03/23/2021] [Indexed: 02/07/2023]
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease of variable clinical severity that is caused by mutations in the survival motor neuron 1 (SMN1) gene. Despite its name, SMN is a ubiquitous protein that functions within and outside the nervous system and has multiple cellular roles in transcription, translation, and proteostatic mechanisms. Encouragingly, several SMN-directed therapies have recently reached the clinic, albeit this has highlighted the increasing need to develop combinatorial therapies for SMA to achieve full clinical efficacy. As a subcellular site of dysfunction in SMA, mitochondria represents a relevant target for a combinatorial therapy. Accordingly, we will discuss our current understanding of mitochondrial dysfunction in SMA, highlighting mitochondrial-based pathways that offer further mechanistic insights into the involvement of mitochondria in SMA. This may ultimately facilitate translational development of targeted mitochondrial therapies for SMA. Due to clinical and mechanistic overlaps, such strategies may also benefit other motor neuron diseases and related neurodegenerative disorders.
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Affiliation(s)
- Rachel James
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Helena Chaytow
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Leire M Ledahawsky
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Thomas H Gillingwater
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK.
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK.
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34
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Backes S, Bykov YS, Flohr T, Räschle M, Zhou J, Lenhard S, Krämer L, Mühlhaus T, Bibi C, Jann C, Smith JD, Steinmetz LM, Rapaport D, Storchová Z, Schuldiner M, Boos F, Herrmann JM. The chaperone-binding activity of the mitochondrial surface receptor Tom70 protects the cytosol against mitoprotein-induced stress. Cell Rep 2021; 35:108936. [PMID: 33826901 PMCID: PMC7615001 DOI: 10.1016/j.celrep.2021.108936] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/22/2020] [Accepted: 03/11/2021] [Indexed: 02/08/2023] Open
Abstract
Most mitochondrial proteins are synthesized as precursors in the cytosol and post-translationally transported into mitochondria. The mitochondrial surface protein Tom70 acts at the interface of the cytosol and mitochondria. In vitro import experiments identified Tom70 as targeting receptor, particularly for hydrophobic carriers. Using in vivo methods and high-content screens, we revisit the question of Tom70 function and considerably expand the set of Tom70-dependent mitochondrial proteins. We demonstrate that the crucial activity of Tom70 is its ability to recruit cytosolic chaperones to the outer membrane. Indeed, tethering an unrelated chaperone-binding domain onto the mitochondrial surface complements most of the defects caused by Tom70 deletion. Tom70-mediated chaperone recruitment reduces the proteotoxicity of mitochondrial precursor proteins, particularly of hydrophobic inner membrane proteins. Thus, our work suggests that the predominant function of Tom70 is to tether cytosolic chaperones to the outer mitochondrial membrane, rather than to serve as a mitochondrion-specifying targeting receptor.
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Affiliation(s)
- Sandra Backes
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Yury S Bykov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tamara Flohr
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Markus Räschle
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jialin Zhou
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Svenja Lenhard
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Lena Krämer
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Timo Mühlhaus
- Computational Systems Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Chen Bibi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Cosimo Jann
- Genome Biology Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany; Department of Biology, Institute of Biochemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Justin D Smith
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lars M Steinmetz
- Genome Biology Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany; Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Zuzana Storchová
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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35
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Abstract
Mitochondria are organelles central to myriad cellular processes. To maintain mitochondrial health, various processes co-operate at both the molecular and organelle level. At the molecular level, mitochondria can sense imbalances in their homeostasis and adapt to these by signaling to the nucleus. This mito-nuclear communication leads to the expression of nuclear stress response genes. Upon external stimuli, mitochondria can also alter their morphology accordingly, by inducing fission or fusion. In an extreme situation, mitochondria are degraded by mitophagy. Adequate function and regulation of these mitochondrial quality control pathways are crucial for cellular homeostasis. As we discuss, alterations in these processes have been linked to several pathologies including neurodegenerative diseases and cancer.
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36
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Sam PN, Calzada E, Acoba MG, Zhao T, Watanabe Y, Nejatfard A, Trinidad JC, Shutt TE, Neal SE, Claypool SM. Impaired phosphatidylethanolamine metabolism activates a reversible stress response that detects and resolves mutant mitochondrial precursors. iScience 2021; 24:102196. [PMID: 33718843 PMCID: PMC7921845 DOI: 10.1016/j.isci.2021.102196] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 01/27/2021] [Accepted: 02/10/2021] [Indexed: 02/06/2023] Open
Abstract
Phosphatidylethanolamine (PE) made in mitochondria has long been recognized as an important precursor for phosphatidylcholine production that occurs in the endoplasmic reticulum (ER). Recently, the strict mitochondrial localization of the enzyme that makes PE in the mitochondrion, phosphatidylserine decarboxylase 1 (Psd1), was questioned. Since a dual localization of Psd1 to the ER would have far-reaching implications, we initiated our study to independently re-assess the subcellular distribution of Psd1. Our results support the unavoidable conclusion that the vast majority, if not all, of functional Psd1 resides in the mitochondrion. Through our efforts, we discovered that mutant forms of Psd1 that impair a self-processing step needed for it to become functional are dually localized to the ER when expressed in a PE-limiting environment. We conclude that severely impaired cellular PE metabolism provokes an ER-assisted adaptive response that is capable of identifying and resolving nonfunctional mitochondrial precursors.
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Affiliation(s)
- Pingdewinde N. Sam
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Elizabeth Calzada
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michelle Grace Acoba
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Tian Zhao
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Yasunori Watanabe
- Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, Yamagata 990-8560, Japan
| | - Anahita Nejatfard
- Division of Biological Sciences, The Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | | | - Timothy E. Shutt
- Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, Yamagata 990-8560, Japan
| | - Sonya E. Neal
- Division of Biological Sciences, The Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | - Steven M. Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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37
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Shakya VP, Barbeau WA, Xiao T, Knutson CS, Schuler MH, Hughes AL. A nuclear-based quality control pathway for non-imported mitochondrial proteins. eLife 2021; 10:61230. [PMID: 33734083 PMCID: PMC7993989 DOI: 10.7554/elife.61230] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 03/17/2021] [Indexed: 01/08/2023] Open
Abstract
Mitochondrial import deficiency causes cellular toxicity due to the accumulation of non-imported mitochondrial precursor proteins, termed mitoprotein-induced stress. Despite the burden mis-localized mitochondrial precursors place on cells, our understanding of the systems that dispose of these proteins is incomplete. Here, we cataloged the location and steady-state abundance of mitochondrial precursor proteins during mitochondrial impairment in Saccharomyces cerevisiae. We found that a number of non-imported mitochondrial proteins localize to the nucleus, where they are subjected to proteasome-dependent degradation through a process we term nuclear-associated mitoprotein degradation (mitoNUC). Recognition and destruction of mitochondrial precursors by the mitoNUC pathway requires the presence of an N-terminal mitochondrial targeting sequence and is mediated by combined action of the E3 ubiquitin ligases San1, Ubr1, and Doa10. Impaired breakdown of precursors leads to alternative sequestration in nuclear-associated foci. These results identify the nucleus as an important destination for the disposal of non-imported mitochondrial precursors.
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Affiliation(s)
- Viplendra Ps Shakya
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - William A Barbeau
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Tianyao Xiao
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Christina S Knutson
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Max H Schuler
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Adam L Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
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38
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Laborenz J, Bykov YS, Knöringer K, Räschle M, Filker S, Prescianotto-Baschong C, Spang A, Tatsuta T, Langer T, Storchová Z, Schuldiner M, Herrmann JM. The ER protein Ema19 facilitates the degradation of nonimported mitochondrial precursor proteins. Mol Biol Cell 2021; 32:664-674. [PMID: 33596095 PMCID: PMC8108515 DOI: 10.1091/mbc.e20-11-0748] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
For the biogenesis of mitochondria, hundreds of proteins need to be targeted from the cytosol into the various compartments of this organelle. The intramitochondrial targeting routes these proteins take to reach their respective location in the organelle are well understood. However, the early targeting processes, from cytosolic ribosomes to the membrane of the organelle, are still largely unknown. In this study, we present evidence that an integral membrane protein of the endoplasmic reticulum (ER), Ema19, plays a role in this process. Mutants lacking Ema19 show an increased stability of mitochondrial precursor proteins, indicating that Ema19 promotes the proteolytic degradation of nonproductive precursors. The deletion of Ema19 improves the growth of respiration-deficient cells, suggesting that Ema19-mediated degradation can compete with productive protein import into mitochondria. Ema19 is the yeast representative of a conserved protein family. The human Ema19 homologue is known as sigma 2 receptor or TMEM97. Though its molecular function is not known, previous studies suggested a role of the sigma 2 receptor as a quality control factor in the ER, compatible with our observations about Ema19. More globally, our data provide an additional demonstration of the important role of the ER in mitochondrial protein targeting.
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Affiliation(s)
- Janina Laborenz
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Yury S Bykov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | | | - Markus Räschle
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Sabine Filker
- Molecular Ecology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | | | - Anne Spang
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Takashi Tatsuta
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Thomas Langer
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Zuzana Storchová
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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39
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Mitochondrial control of cellular protein homeostasis. Biochem J 2021; 477:3033-3054. [PMID: 32845275 DOI: 10.1042/bcj20190654] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/20/2020] [Accepted: 08/03/2020] [Indexed: 02/08/2023]
Abstract
Mitochondria are involved in several vital functions of the eukaryotic cell. The majority of mitochondrial proteins are coded by nuclear DNA. Constant import of proteins from the cytosol is a prerequisite for the efficient functioning of the organelle. The protein import into mitochondria is mediated by diverse import pathways and is continuously under watch by quality control systems. However, it is often challenged by both internal and external factors, such as oxidative stress or energy shortage. The impaired protein import and biogenesis leads to the accumulation of mitochondrial precursor proteins in the cytosol and activates several stress response pathways. These defense mechanisms engage a network of processes involving transcription, translation, and protein clearance to restore cellular protein homeostasis. In this review, we provide a comprehensive analysis of various factors and processes contributing to mitochondrial stress caused by protein biogenesis failure and summarize the recovery mechanisms employed by the cell.
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40
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Xiao T, Shakya VP, Hughes AL. ER targeting of non-imported mitochondrial carrier proteins is dependent on the GET pathway. Life Sci Alliance 2021; 4:4/3/e202000918. [PMID: 33479049 PMCID: PMC7898604 DOI: 10.26508/lsa.202000918] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/06/2021] [Accepted: 01/06/2021] [Indexed: 12/24/2022] Open
Abstract
The GET pathway is required to target non-imported mitochondrial carrier proteins to the endoplasmic reticulum, which prevents their deposition into Hsp42-dependent protein foci. Deficiencies in mitochondrial import cause the toxic accumulation of non-imported mitochondrial precursor proteins. Numerous fates for non-imported mitochondrial precursors have been identified in budding yeast, including proteasomal destruction, deposition into protein aggregates, and mistargeting to other organelles. Amongst organelles, the ER has emerged as a key destination for a subset of non-imported mitochondrial proteins. However, how ER targeting of various types of mitochondrial proteins is achieved remains incompletely understood. Here, we show that the ER delivery of endogenous mitochondrial transmembrane proteins, especially those belonging to the SLC25A mitochondrial carrier family, is dependent on the guided entry of tail-anchored proteins (GET) complex. Without a functional GET pathway, non-imported mitochondrial proteins destined for the ER are alternatively sequestered into Hsp42-dependent protein foci. Loss of the GET pathway is detrimental to yeast cells experiencing mitochondrial import failure and prevents re-import of mitochondrial proteins from the ER via the ER-SURF pathway. Overall, this study outlines an important role for the GET complex in ER targeting of non-imported mitochondrial carrier proteins.
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Affiliation(s)
- Tianyao Xiao
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Viplendra Ps Shakya
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Adam L Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
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41
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Ali M, Boosi Narayana Rao K, Majumder P, Sarkar R, Mapa K. Alterations in inter-organelle crosstalk and Ca 2+ signaling through mitochondria during proteotoxic stresses. Mitochondrion 2020; 57:37-46. [PMID: 33340711 DOI: 10.1016/j.mito.2020.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/25/2020] [Accepted: 12/10/2020] [Indexed: 01/06/2023]
Abstract
BACKGROUND Biogenesis and function of mitochondria is profoundly dependent on cytosolic translation of mitochondrial pre-proteins and its subsequent translocation and folding inside the organelle. Continuous exposure of non-native precursor proteins, exposure to damaging by-products of oxidative phosphorylation, load of mis-targeted or misfolded proteins from neighbouring compartments and unremitting demand of communication between mitochondrial and nuclear genomes, continuously pose proteotoxic threats to the organelle. Our knowledge of cellular mechanisms to cope up with such impending threat of proteotoxicity to mitochondria, is currently evolving. In recent years, several unique response and survival pathways have been discovered shedding light on cellular strategies to cope with stressed and dysfunctional mitochondria. As mitochondria compulsorily communicate with nucleus, cytosol and endoplasmic reticulum (ER) for its own biogenesis and function and in turn maintain critical cellular processes for survival, any impairment in communication by stressed or dysfunctional mitochondria may end up with fatal consequences. DISCUSSION AND IMPLICATION In this review, we have discussed about possible sources of mitochondrial proteotoxicity and the recent developments regarding cellular strategies to counter such stress to overcome dysfunctions of the organelle. Mitochondrial communication with neighbouring subcellular compartments like ER and cytosol during proteotoxic stress have been explored. In the context of mitochondrial proteotoxicity, alterations of crucial inter-organelle connections like ER-mitochondria contact sites and its implication on mitochondrial signaling activity like Ca2+ signaling have been dissected. Furthermore, an overview of pathological conditions, mainly neurodegenerative disorders that are known to be associated with mitochondrial proteotoxicity and Ca2+ dysregulation has been presented.
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Affiliation(s)
- Mudassar Ali
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Kannan Boosi Narayana Rao
- Proteomics and Structural Biology Unit, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi 110025, India; Academy of Scientific and Innovative Research, CSIR-HRDG, Ghaziabad, Uttar Pradesh 201002, India
| | - Priyanka Majumder
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Rajasri Sarkar
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Koyeli Mapa
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, Gautam Buddha Nagar, Uttar Pradesh 201314, India; Academy of Scientific and Innovative Research, CSIR-HRDG, Ghaziabad, Uttar Pradesh 201002, India.
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42
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Krämer L, Groh C, Herrmann JM. The proteasome: friend and foe of mitochondrial biogenesis. FEBS Lett 2020; 595:1223-1238. [PMID: 33249599 DOI: 10.1002/1873-3468.14010] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/26/2020] [Accepted: 11/01/2020] [Indexed: 01/06/2023]
Abstract
Most mitochondrial proteins are synthesized in the cytosol and subsequently translocated as unfolded polypeptides into mitochondria. Cytosolic chaperones maintain precursor proteins in an import-competent state. This post-translational import reaction is under surveillance of the cytosolic ubiquitin-proteasome system, which carries out several distinguishable activities. On the one hand, the proteasome degrades nonproductive protein precursors from the cytosol and nucleus, import intermediates that are stuck in mitochondrial translocases, and misfolded or damaged proteins from the outer membrane and the intermembrane space. These surveillance activities of the proteasome are essential for mitochondrial functionality, as well as cellular fitness and survival. On the other hand, the proteasome competes with mitochondria for nonimported cytosolic precursor proteins, which can compromise mitochondrial biogenesis. In order to balance the positive and negative effects of the cytosolic protein quality control system on mitochondria, mitochondrial import efficiency directly regulates the capacity of the proteasome via transcription factor Rpn4 in yeast and nuclear respiratory factor (Nrf) 1 and 2 in animal cells. In this review, we provide a thorough overview of how the proteasome regulates mitochondrial biogenesis.
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Affiliation(s)
- Lena Krämer
- Cell Biology, University of Kaiserslautern, Germany
| | - Carina Groh
- Cell Biology, University of Kaiserslautern, Germany
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43
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English J, Son JM, Cardamone MD, Lee C, Perissi V. Decoding the rosetta stone of mitonuclear communication. Pharmacol Res 2020; 161:105161. [PMID: 32846213 PMCID: PMC7755734 DOI: 10.1016/j.phrs.2020.105161] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/04/2020] [Accepted: 08/14/2020] [Indexed: 12/12/2022]
Abstract
Cellular homeostasis in eukaryotic cells requires synchronized coordination of multiple organelles. A key role in this stage is played by mitochondria, which have recently emerged as highly interconnected and multifunctional hubs that process and coordinate diverse cellular functions. Beyond producing ATP, mitochondria generate key metabolites and are central to apoptotic and metabolic signaling pathways. Because most mitochondrial proteins are encoded in the nuclear genome, the biogenesis of new mitochondria and the maintenance of mitochondrial functions and flexibility critically depend upon effective mitonuclear communication. This review addresses the complex network of signaling molecules and pathways allowing mitochondria-nuclear communication and coordinated regulation of their independent but interconnected genomes, and discusses the extent to which dynamic communication between the two organelles has evolved for mutual benefit and for the overall maintenance of cellular and organismal fitness.
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Affiliation(s)
- Justin English
- Department of Biochemistry, Boston University, Boston, MA, 02115, USA; Graduate Program in Biomolecular Pharmacology, Department of Pharmacology and Experimental Therapeutics, Boston University, Boston, MA, 02115, USA
| | - Jyung Mean Son
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
| | | | - Changhan Lee
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA; USC Norris Comprehensive Cancer Center, Los Angeles, CA, 90089, USA; Biomedical Sciences, Graduate School, Ajou University, Suwon, 16499, South Korea
| | - Valentina Perissi
- Department of Biochemistry, Boston University, Boston, MA, 02115, USA.
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44
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Zöller E, Laborenz J, Krämer L, Boos F, Räschle M, Alexander RT, Herrmann JM. The intermembrane space protein Mix23 is a novel stress-induced mitochondrial import factor. J Biol Chem 2020; 295:14686-14697. [PMID: 32826315 PMCID: PMC7586232 DOI: 10.1074/jbc.ra120.014247] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/19/2020] [Indexed: 12/20/2022] Open
Abstract
The biogenesis of mitochondria requires the import of hundreds of precursor proteins. These proteins are transported post-translationally with the help of chaperones, meaning that the overproduction of mitochondrial proteins or the limited availability of chaperones can lead to the accumulation of cytosolic precursor proteins. This imposes a severe challenge to cytosolic proteostasis and triggers a specific transcription program called the mitoprotein-induced stress response, which activates the proteasome system. This coincides with the repression of mitochondrial proteins, including many proteins of the intermembrane space. In contrast, herein we report that the so-far-uncharacterized intermembrane space protein Mix23 is considerably up-regulated when mitochondrial import is perturbed. Mix23 is evolutionarily conserved and a homolog of the human protein CCDC58. We found that, like the subunits of the proteasome, Mix23 is under control of the transcription factor Rpn4. It is imported into mitochondria by the mitochondrial disulfide relay. Mix23 is critical for the efficient import of proteins into the mitochondrial matrix, particularly if the function of the translocase of the inner membrane 23 is compromised such as in temperature-sensitive mutants of Tim17. Our observations identify Mix23 as a novel regulator or stabilizer of the mitochondrial protein import machinery that is specifically up-regulated upon mitoprotein-induced stress conditions.
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Affiliation(s)
- Eva Zöller
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Janina Laborenz
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Lena Krämer
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Felix Boos
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Markus Räschle
- Department of Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - R Todd Alexander
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Johannes M Herrmann
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany.
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45
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Abstract
Mitochondria contain about 1,000-1,500 proteins that fulfil multiple functions. Mitochondrial proteins originate from two genomes: mitochondrial and nuclear. Hence, proper mitochondrial function requires synchronization of gene expression in the nucleus and in mitochondria and necessitates efficient import of mitochondrial proteins into the organelle from the cytosol. Furthermore, the mitochondrial proteome displays high plasticity to allow the adaptation of mitochondrial function to cellular requirements. Maintenance of this complex and adaptable mitochondrial proteome is challenging, but is of crucial importance to cell function. Defects in mitochondrial proteostasis lead to proteotoxic insults and eventually cell death. Different quality control systems monitor the mitochondrial proteome. The cytosolic ubiquitin-proteasome system controls protein transport across the mitochondrial outer membrane and removes damaged or mislocalized proteins. Concomitantly, a number of mitochondrial chaperones and proteases govern protein folding and degrade damaged proteins inside mitochondria. The quality control factors also regulate processing and turnover of native proteins to control protein import, mitochondrial metabolism, signalling cascades, mitochondrial dynamics and lipid biogenesis, further ensuring proper function of mitochondria. Thus, mitochondrial protein quality control mechanisms are of pivotal importance to integrate mitochondria into the cellular environment.
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46
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Escobar-Henriques M, Anton V. Mitochondrial Surveillance by Cdc48/p97: MAD vs. Membrane Fusion. Int J Mol Sci 2020; 21:E6841. [PMID: 32961852 PMCID: PMC7555132 DOI: 10.3390/ijms21186841] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 11/16/2022] Open
Abstract
Cdc48/p97 is a ring-shaped, ATP-driven hexameric motor, essential for cellular viability. It specifically unfolds and extracts ubiquitylated proteins from membranes or protein complexes, mostly targeting them for proteolytic degradation by the proteasome. Cdc48/p97 is involved in a multitude of cellular processes, reaching from cell cycle regulation to signal transduction, also participating in growth or death decisions. The role of Cdc48/p97 in endoplasmic reticulum-associated degradation (ERAD), where it extracts proteins targeted for degradation from the ER membrane, has been extensively described. Here, we present the roles of Cdc48/p97 in mitochondrial regulation. We discuss mitochondrial quality control surveillance by Cdc48/p97 in mitochondrial-associated degradation (MAD), highlighting the potential pathologic significance thereof. Furthermore, we present the current knowledge of how Cdc48/p97 regulates mitofusin activity in outer membrane fusion and how this may impact on neurodegeneration.
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Affiliation(s)
- Mafalda Escobar-Henriques
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, Joseph-Stelzmann-Straße 26, 50931 Cologne, Germany;
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47
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Gioran A, Chondrogianni N. Mitochondria (cross)talk with proteostatic mechanisms: Focusing on ageing and neurodegenerative diseases. Mech Ageing Dev 2020; 190:111324. [DOI: 10.1016/j.mad.2020.111324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/15/2022]
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48
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Proteotoxic Stress and Cell Death in Cancer Cells. Cancers (Basel) 2020; 12:cancers12092385. [PMID: 32842524 PMCID: PMC7563887 DOI: 10.3390/cancers12092385] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/19/2020] [Accepted: 08/20/2020] [Indexed: 02/06/2023] Open
Abstract
To maintain proteostasis, cells must integrate information and activities that supervise protein synthesis, protein folding, conformational stability, and also protein degradation. Extrinsic and intrinsic conditions can both impact normal proteostasis, causing the appearance of proteotoxic stress. Initially, proteotoxic stress elicits adaptive responses aimed at restoring proteostasis, allowing cells to survive the stress condition. However, if the proteostasis restoration fails, a permanent and sustained proteotoxic stress can be deleterious, and cell death ensues. Many cancer cells convive with high levels of proteotoxic stress, and this condition could be exploited from a therapeutic perspective. Understanding the cell death pathways engaged by proteotoxic stress is instrumental to better hijack the proliferative fate of cancer cells.
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49
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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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50
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Bertgen L, Mühlhaus T, Herrmann JM. Clingy genes: Why were genes for ribosomal proteins retained in many mitochondrial genomes? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148275. [PMID: 32712152 DOI: 10.1016/j.bbabio.2020.148275] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/14/2020] [Accepted: 07/19/2020] [Indexed: 11/18/2022]
Abstract
Why mitochondria still retain their own genome is a puzzle given the enormous effort to maintain a mitochondrial translation machinery. Most mitochondrially encoded proteins are membrane-embedded subunits of the respiratory chain. Their hydrophobicity presumably impedes their import into mitochondria. However, many mitochondrial genomes also encode protein subunits of the mitochondrial ribosome. These proteins lack transmembrane domains and hydrophobicity cannot explain why their genes remained in mitochondria. In this review, we provide an overview about mitochondrially encoded subunits of mitochondrial ribosomes of fungi, plants and protists. Moreover, we discuss and evaluate different hypotheses which were put forward to explain why (ribosomal) proteins remained mitochondrially encoded. It seems likely that the synthesis of ribosomal proteins in the mitochondrial matrix is used to regulate the assembly of the mitochondrial ribosome within mitochondria and to avoid problems that mitochondrial proteins might pose for cytosolic proteostasis and for the assembly of cytosolic ribosomes.
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Affiliation(s)
- Lea Bertgen
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 13, 67663 Kaiserslautern, Germany
| | - Timo Mühlhaus
- Computational Systems Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 23, 67663 Kaiserslautern, Germany
| | - Johannes M Herrmann
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 13, 67663 Kaiserslautern, Germany.
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