1
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Wilson ZN, Balasubramaniam SS, Wong S, Schuler MH, Wopat MJ, Hughes AL. Mitochondrial-derived compartments remove surplus proteins from the outer mitochondrial membrane. J Cell Biol 2024; 223:e202307036. [PMID: 39136938 PMCID: PMC11320589 DOI: 10.1083/jcb.202307036] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 05/24/2024] [Accepted: 07/18/2024] [Indexed: 09/13/2024] Open
Abstract
The outer mitochondrial membrane (OMM) creates a boundary that imports most of the mitochondrial proteome while removing extraneous or damaged proteins. How the OMM senses aberrant proteins and remodels to maintain OMM integrity remains unresolved. Previously, we identified a mitochondrial remodeling mechanism called the mitochondrial-derived compartment (MDC) that removes a subset of the mitochondrial proteome. Here, we show that MDCs specifically sequester proteins localized only at the OMM, providing an explanation for how select mitochondrial proteins are incorporated into MDCs. Remarkably, selective sorting into MDCs also occurs within the OMM, as subunits of the translocase of the outer membrane (TOM) complex are excluded from MDCs unless assembly of the TOM complex is impaired. Considering that overloading the OMM with mitochondrial membrane proteins or mistargeted tail-anchored membrane proteins induces MDCs to form and sequester these proteins, we propose that one functional role of MDCs is to create an OMM-enriched trap that segregates and sequesters excess proteins from the mitochondrial surface.
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Affiliation(s)
- Zachary N Wilson
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | | | - Sara Wong
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Max-Hinderk Schuler
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Mitchell J Wopat
- 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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2
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Müller L, Hoppe T. UPS-dependent strategies of protein quality control degradation. Trends Biochem Sci 2024; 49:859-874. [PMID: 38945729 DOI: 10.1016/j.tibs.2024.06.006] [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: 03/07/2024] [Revised: 05/29/2024] [Accepted: 06/10/2024] [Indexed: 07/02/2024]
Abstract
The degradation of damaged proteins is critical for tissue integrity and organismal health because damaged proteins have a high propensity to form aggregates. E3 ubiquitin ligases are key regulators of protein quality control (PQC) and mediate the selective degradation of damaged proteins, a process termed 'PQC degradation' (PQCD). The degradation signals (degrons) that trigger PQCD are based on hydrophobic sites that are normally buried within the native protein structure. However, an open question is how PQCD-specialized E3 ligases distinguish between transiently misfolded proteins, which can be efficiently refolded, and permanently damaged proteins, which must be degraded. While significant progress has been made in characterizing degradation determinants, understanding the key regulatory signals of cellular and organismal PQCD pathways remains a challenge.
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Affiliation(s)
- Leonie Müller
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine and University Hospital of Cologne, 50931 Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine and University Hospital of Cologne, 50931 Cologne, Germany.
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3
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Jagtap YA, Kumar P, Dubey AR, Kinger S, Choudhary A, Karmakar S, Lal G, Kumar A, Kumar A, Prasad A, Mishra A. Acetaminophen induces mitochondrial apoptosis through proteasome dysfunctions. Life Sci 2024; 349:122732. [PMID: 38768775 DOI: 10.1016/j.lfs.2024.122732] [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: 11/15/2023] [Revised: 03/12/2024] [Accepted: 05/15/2024] [Indexed: 05/22/2024]
Abstract
Acetaminophen is a known antipyretic and non-opioid analgesic for mild pain and fever. Numerous studies uncover their hidden chemotherapeutics applications, including chronic cancer pain management. Acetaminophen also represents an anti-proliferative effect in some cancer cells. Few studies also suggest that the use of Acetaminophen can trigger apoptosis and impede cellular growth. However, Acetaminophen's molecular potential and precise mechanism against improper cellular proliferation and use as an effective anti-proliferative agent still need to be better understood. Here, our current findings show that Acetaminophen induces proteasomal dysfunctions, resulting in aberrant protein accumulation and mitochondrial abnormalities, and consequently induces cell apoptosis. We observed that the Acetaminophen treatment leads to improper aggregation of ubiquitylated expanded polyglutamine proteins, which may be due to the dysfunctions of proteasome activities. Our in-silico analysis suggests the interaction of Acetaminophen and proteasome. Furthermore, we demonstrated the accumulation of proteasome substrates and the depletion of proteasome activities after treating Acetaminophen in cells. Acetaminophen induces proteasome dysfunctions and mitochondrial abnormalities, leading to pro-apoptotic morphological changes and apoptosis successively. These results suggest that Acetaminophen can induce cell death and may retain a promising anti-proliferative effect. These observations can open new possible molecular strategies in the near future for developing and designing specific and effective proteasome inhibitors, which can be helpful in conjugation with other anti-tumor drugs for their better efficiency.
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Affiliation(s)
- Yuvraj Anandrao Jagtap
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Rajasthan, 342037, India
| | - Prashant Kumar
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Rajasthan, 342037, India
| | - Ankur Rakesh Dubey
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Rajasthan, 342037, India
| | - Sumit Kinger
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Rajasthan, 342037, India
| | - Akash Choudhary
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Rajasthan, 342037, India
| | - Surojit Karmakar
- National Centre for Cell Science (NCCS), Ganeshkhind, Pune, Maharashtra, 411007, India
| | - Girdhari Lal
- National Centre for Cell Science (NCCS), Ganeshkhind, Pune, Maharashtra, 411007, India
| | - Awanish Kumar
- Department of Biotechnology, National Institute of Technology, Raipur, Chhattisgarh, 492010, India
| | - Amit Kumar
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, Madhya Pradesh, 453552, India
| | - Amit Prasad
- School of Biosciences and Bioengineering, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, 175005, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Rajasthan, 342037, India.
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4
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Reed JN, Huang J, Li Y, Ma L, Banka D, Wabitsch M, Wang T, Ding W, Björkegren JL, Civelek M. Systems genetics analysis of human body fat distribution genes identifies adipocyte processes. Life Sci Alliance 2024; 7:e202402603. [PMID: 38702075 PMCID: PMC11068934 DOI: 10.26508/lsa.202402603] [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: 01/18/2024] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 05/06/2024] Open
Abstract
Excess abdominal fat is a sexually dimorphic risk factor for cardio-metabolic disease and is approximated by the waist-to-hip ratio adjusted for body mass index (WHRadjBMI). Whereas this trait is highly heritable, few causal genes are known. We aimed to identify novel drivers of WHRadjBMI using systems genetics. We used two independent cohorts of adipose tissue gene expression and constructed sex- and depot-specific Bayesian networks to model gene-gene interactions from 8,492 genes. Using key driver analysis, we identified genes that, in silico and putatively in vitro, regulate many others. 51-119 key drivers in each network were replicated in both cohorts. In other cell types, 23 of these genes are found in crucial adipocyte pathways: Wnt signaling or mitochondrial function. We overexpressed or down-regulated seven key driver genes in human subcutaneous pre-adipocytes. Key driver genes ANAPC2 and RSPO1 inhibited adipogenesis, whereas PSME3 increased adipogenesis. RSPO1 increased Wnt signaling activity. In differentiated adipocytes, MIGA1 and UBR1 down-regulation led to mitochondrial dysfunction. These five genes regulate adipocyte function, and we hypothesize that they regulate fat distribution.
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Affiliation(s)
- Jordan N Reed
- https://ror.org/0153tk833 Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
- https://ror.org/0153tk833 Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
| | - Jiansheng Huang
- Novo Nordisk Research Center China, Novo Nordisk A/S, Beijing, China
| | - Yong Li
- Novo Nordisk Research Center China, Novo Nordisk A/S, Beijing, China
| | - Lijiang Ma
- https://ror.org/04a9tmd77 Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Dhanush Banka
- https://ror.org/0153tk833 Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Martin Wabitsch
- Division of Paediatric Endocrinology and Diabetes, Department of Paediatrics and Adolescent Medicine, Ulm University Medical Centre, Ulm, Germany
| | - Tianfang Wang
- Novo Nordisk Research Center China, Novo Nordisk A/S, Beijing, China
| | - Wen Ding
- Novo Nordisk Research Center China, Novo Nordisk A/S, Beijing, China
| | - Johan Lm Björkegren
- https://ror.org/04a9tmd77 Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Medicine, Karolinska Institutet, Huddinge, Stockholm, Sweden
| | - Mete Civelek
- https://ror.org/0153tk833 Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
- https://ror.org/0153tk833 Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
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5
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Pines O, Horwitz M, Herrmann JM. Privileged proteins with a second residence: dual targeting and conditional re-routing of mitochondrial proteins. FEBS J 2024. [PMID: 38857249 DOI: 10.1111/febs.17191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/15/2024] [Accepted: 05/22/2024] [Indexed: 06/12/2024]
Abstract
Almost all mitochondrial proteins are encoded by nuclear genes and synthesized in the cytosol as precursor proteins. Signals in the amino acid sequence of these precursors ensure their targeting and translocation into mitochondria. However, in many cases, only a certain fraction of a specific protein is transported into mitochondria, while the rest either remains in the cytosol or undergoes reverse translocation to the cytosol, and can populate other cellular compartments. This phenomenon is called dual localization which can be instigated by different mechanisms. These include alternative start or stop codons, differential transcripts, and ambiguous or competing targeting sequences. In many cases, dual localization might serve as an economic strategy to reduce the number of required genes; for example, when the same groups of enzymes are required both in mitochondria and chloroplasts or both in mitochondria and the nucleus/cytoplasm. Such cases frequently employ ambiguous targeting sequences to distribute proteins between both organelles. However, alternative localizations can also be used for signaling, for example when non-imported precursors serve as mitophagy signals or when they represent transcription factors in the nucleus to induce the mitochondrial unfolded stress response. This review provides an overview regarding the mechanisms and the physiological consequences of dual targeting.
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Affiliation(s)
- Ophry Pines
- Microbiology and Genetics, Faculty of Medicine, Hebrew University of Jerusalem, Israel
| | - Margalit Horwitz
- Microbiology and Genetics, Faculty of Medicine, Hebrew University of Jerusalem, Israel
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6
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Ikeda T, Yamazaki K, Okumura F, Kamura T, Nakatsukasa K. Role of the San1 ubiquitin ligase in the heat stress-induced degradation of nonnative Nup1 in the nuclear pore complex. Genetics 2024; 226:iyae017. [PMID: 38302116 DOI: 10.1093/genetics/iyae017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 11/21/2022] [Accepted: 01/23/2024] [Indexed: 02/03/2024] Open
Abstract
The nuclear pore complex (NPC) mediates the selective exchange of macromolecules between the nucleus and the cytoplasm. Neurodegenerative diseases such as amyotrophic lateral sclerosis are characterized by mislocalization of nucleoporins (Nups), transport receptors, and Ras-related nuclear proteins into nucleoplasmic or cytosolic aggregates, underscoring the importance of precise assembly of the NPC. The assembly state of large protein complexes is strictly monitored by the protein quality control system. The ubiquitin-proteasome system may eliminate aberrant, misfolded, and/or orphan components; however, the involvement of the ubiquitin-proteasome system in the degradation of nonnative Nups in the NPC remains unclear. Here, we show that in Saccharomyces cerevisiae, although Nup1 (the FG-Nup component of the central core of the NPC) was stable, C-terminally green fluorescent protein-tagged Nup1, which had been incorporated into the NPC, was degraded by the proteasome especially under heat stress conditions. The degradation was dependent on the San1 ubiquitin ligase and Cdc48/p97, as well as its cofactor Doa1. We also demonstrate that San1 weakly but certainly contributes to the degradation of nontagged endogenous Nup1 in cells defective in NPC biogenesis by the deletion of NUP120. In addition, the overexpression of SAN1 exacerbated the growth defect phenotype of nup120Δ cells, which may be caused by excess degradation of defective Nups due to the deletion of NUP120. These biochemical and genetic data suggest that San1 is involved in the degradation of nonnative Nups generated by genetic mutation or when NPC biogenesis is impaired.
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Affiliation(s)
- Takanari Ikeda
- Graduate School of Science, Nagoya City University, Nagoya, Aichi 467-8501, Japan
| | - Kenji Yamazaki
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Fumihiko Okumura
- Department of Food and Health Sciences, International College of Arts and Sciences, Fukuoka Women's University, Fukuoka, Fukuoka 813-8529, Japan
| | - Takumi Kamura
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Kunio Nakatsukasa
- Graduate School of Science, Nagoya City University, Nagoya, Aichi 467-8501, Japan
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7
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Koch C, Lenhard S, Räschle M, Prescianotto-Baschong C, Spang A, Herrmann JM. The ER-SURF pathway uses ER-mitochondria contact sites for protein targeting to mitochondria. EMBO Rep 2024; 25:2071-2096. [PMID: 38565738 PMCID: PMC11014988 DOI: 10.1038/s44319-024-00113-w] [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: 08/31/2023] [Revised: 02/14/2024] [Accepted: 02/20/2024] [Indexed: 04/04/2024] Open
Abstract
Most mitochondrial proteins are synthesized on cytosolic ribosomes and imported into mitochondria in a post-translational reaction. Mitochondrial precursor proteins which use the ER-SURF pathway employ the surface of the endoplasmic reticulum (ER) as an important sorting platform. How they reach the mitochondrial import machinery from the ER is not known. Here we show that mitochondrial contact sites play a crucial role in the ER-to-mitochondria transfer of precursor proteins. The ER mitochondria encounter structure (ERMES) and Tom70, together with Djp1 and Lam6, are part of two parallel and partially redundant ER-to-mitochondria delivery routes. When ER-to-mitochondria transfer is prevented by loss of these two contact sites, many precursors of mitochondrial inner membrane proteins are left stranded on the ER membrane, resulting in mitochondrial dysfunction. Our observations support an active role of the ER in mitochondrial protein biogenesis.
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Affiliation(s)
- Christian Koch
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Svenja Lenhard
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Markus Räschle
- Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | | | - Anne Spang
- Biozentrum, University of Basel, 4056, Basel, Switzerland
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8
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Yang EJN, Liao PC, Pon L. Mitochondrial protein and organelle quality control-Lessons from budding yeast. IUBMB Life 2024; 76:72-87. [PMID: 37731280 PMCID: PMC10842221 DOI: 10.1002/iub.2783] [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: 06/30/2023] [Accepted: 08/11/2023] [Indexed: 09/22/2023]
Abstract
Mitochondria are essential for normal cellular function and have emerged as key aging determinants. Indeed, defects in mitochondrial function have been linked to cardiovascular, skeletal muscle and neurodegenerative diseases, premature aging, and age-linked diseases. Here, we describe mechanisms for mitochondrial protein and organelle quality control. These surveillance mechanisms mediate repair or degradation of damaged or mistargeted mitochondrial proteins, segregate mitochondria based on their functional state during asymmetric cell division, and modulate cellular fitness, the response to stress, and lifespan control in yeast and other eukaryotes.
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Affiliation(s)
- Emily Jie-Ning Yang
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
| | - Pin-Chao Liao
- Institute of Molecular Medicine & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30013
| | - Liza Pon
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
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9
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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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10
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Shin S, Kim J, Lee JY, Kim J, Oh CM. Mitochondrial Quality Control: Its Role in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). J Obes Metab Syndr 2023; 32:289-302. [PMID: 38049180 PMCID: PMC10786205 DOI: 10.7570/jomes23054] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 09/27/2023] [Accepted: 09/30/2023] [Indexed: 12/06/2023] Open
Abstract
Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease, is characterized by hepatic steatosis and metabolic dysfunction and is often associated with obesity and insulin resistance. Recent research indicates a rapid escalation in MASLD cases, with projections suggesting a doubling in the United States by 2030. This review focuses on the central role of mitochondria in the pathogenesis of MASLD and explores potential therapeutic interventions. Mitochondria are dynamic organelles that orchestrate hepatic energy production and metabolism and are critically involved in MASLD. Dysfunctional mitochondria contribute to lipid accumulation, inflammation, and liver fibrosis. Genetic associations further underscore the relationship between mitochondrial dynamics and MASLD susceptibility. Although U.S. Food and Drug Administration-approved treatments for MASLD remain elusive, ongoing clinical trials have highlighted promising strategies that target mitochondrial dysfunction, including vitamin E, metformin, and glucagon-like peptide-1 receptor agonists. In preclinical studies, novel therapeutics, including nicotinamide adenine dinucleotide+ precursors, urolithin A, spermidine, and mitoquinone, have shown beneficial effects, such as improving mitochondrial quality control, reducing oxidative stress, and ameliorating hepatic steatosis and inflammation. In conclusion, mitochondrial dysfunction is central to MASLD pathogenesis. The innovative mitochondria-targeted approaches discussed in this review offer a promising avenue for reducing the burden of MASLD and improving global quality of life.
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Affiliation(s)
- Soyeon Shin
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Jaeyoung Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Ju Yeon Lee
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Jun Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Chang-Myung Oh
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
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11
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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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12
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Uoselis L, Nguyen TN, Lazarou M. Mitochondrial degradation: Mitophagy and beyond. Mol Cell 2023; 83:3404-3420. [PMID: 37708893 DOI: 10.1016/j.molcel.2023.08.021] [Citation(s) in RCA: 38] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 08/10/2023] [Accepted: 08/17/2023] [Indexed: 09/16/2023]
Abstract
Mitochondria are central hubs of cellular metabolism that also play key roles in signaling and disease. It is therefore fundamentally important that mitochondrial quality and activity are tightly regulated. Mitochondrial degradation pathways contribute to quality control of mitochondrial networks and can also regulate the metabolic profile of mitochondria to ensure cellular homeostasis. Here, we cover the many and varied ways in which cells degrade or remove their unwanted mitochondria, ranging from mitophagy to mitochondrial extrusion. The molecular signals driving these varied pathways are discussed, including the cellular and physiological contexts under which the different degradation pathways are engaged.
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Affiliation(s)
- Louise Uoselis
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20185, USA
| | - Thanh Ngoc Nguyen
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20185, USA.
| | - Michael Lazarou
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20185, USA.
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13
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Reed JN, Huang J, Li Y, Ma L, Banka D, Wabitsch M, Wang T, Ding W, Björkegren JLM, Civelek M. Systems genetics analysis of human body fat distribution genes identifies Wnt signaling and mitochondrial activity in adipocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.06.556534. [PMID: 37732278 PMCID: PMC10508754 DOI: 10.1101/2023.09.06.556534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
BACKGROUND Excess fat in the abdomen is a sexually dimorphic risk factor for cardio-metabolic disease. The relative storage between abdominal and lower-body subcutaneous adipose tissue depots is approximated by the waist-to-hip ratio adjusted for body mass index (WHRadjBMI). Genome-wide association studies (GWAS) identified 346 loci near 495 genes associated with WHRadjBMI. Most of these genes have unknown roles in fat distribution, but many are expressed and putatively act in adipose tissue. We aimed to identify novel sex- and depot-specific drivers of WHRadjBMI using a systems genetics approach. METHODS We used two independent cohorts of adipose tissue gene expression with 362 - 444 males and 147 - 219 females, primarily of European ancestry. We constructed sex- and depot- specific Bayesian networks to model the gene-gene interactions from 8,492 adipose tissue genes. Key driver analysis identified genes that, in silico and putatively in vitro, regulate many others, including the 495 WHRadjBMI GWAS genes. Key driver gene function was determined by perturbing their expression in human subcutaneous pre-adipocytes using lenti-virus or siRNA. RESULTS 51 - 119 key drivers in each network were replicated in both cohorts. We used single-cell expression data to select replicated key drivers expressed in adipocyte precursors and mature adipocytes, prioritized genes which have not been previously studied in adipose tissue, and used public human and mouse data to nominate 53 novel key driver genes (10 - 21 from each network) that may regulate fat distribution by altering adipocyte function. In other cell types, 23 of these genes are found in crucial adipocyte pathways: Wnt signaling or mitochondrial function. We selected seven genes whose expression is highly correlated with WHRadjBMI to further study their effects on adipogenesis/Wnt signaling (ANAPC2, PSME3, RSPO1, TYRO3) or mitochondrial function (C1QTNF3, MIGA1, PSME3, UBR1).Adipogenesis was inhibited in cells overexpressing ANAPC2 and RSPO1 compared to controls. RSPO1 results are consistent with a positive correlation between gene expression in the subcutaneous depot and WHRadjBMI, therefore lower relative storage in the subcutaneous depot. RSPO1 inhibited adipogenesis by increasing β-catenin activation and Wnt-related transcription, thus repressing PPARG and CEBPA. PSME3 overexpression led to more adipogenesis than controls. In differentiated adipocytes, MIGA1 and UBR1 downregulation led to mitochondrial dysfunction, with lower oxygen consumption than controls; MIGA1 knockdown also lowered UCP1 expression. SUMMARY ANAPC2, MIGA1, PSME3, RSPO1, and UBR1 affect adipocyte function and may drive body fat distribution.
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14
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Metzger MB, Scales JL, Grant GA, Molnar AE, Loncarek J, Weissman AM. Differential sensitivity of the yeast Lon protease Pim1p to impaired mitochondrial respiration. J Biol Chem 2023; 299:104937. [PMID: 37331598 PMCID: PMC10359500 DOI: 10.1016/j.jbc.2023.104937] [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: 03/31/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/20/2023] Open
Abstract
Mitochondria are essential organelles whose proteome is well protected by regulated protein degradation and quality control. While the ubiquitin-proteasome system can monitor mitochondrial proteins that reside at the mitochondrial outer membrane or are not successfully imported, resident proteases generally act on proteins within mitochondria. Herein, we assess the degradative pathways for mutant forms of three mitochondrial matrix proteins (mas1-1HA, mas2-11HA, and tim44-8HA) in Saccharomyces cerevisiae. The degradation of these proteins is strongly impaired by loss of either the matrix AAA-ATPase (m-AAA) (Afg3p/Yta12p) or Lon (Pim1p) protease. We determine that these mutant proteins are all bona fide Pim1p substrates whose degradation is also blocked in respiratory-deficient "petite" yeast cells, such as in cells lacking m-AAA protease subunits. In contrast, matrix proteins that are substrates of the m-AAA protease are not affected by loss of respiration. The failure to efficiently remove Pim1p substrates in petite cells has no evident relationship to Pim1p maturation, localization, or assembly. However, Pim1p's autoproteolysis is intact, and its overexpression restores substrate degradation, indicating that Pim1p retains some functionality in petite cells. Interestingly, chemical perturbation of mitochondria with oligomycin similarly prevents degradation of Pim1p substrates. Our results demonstrate that Pim1p activity is highly sensitive to mitochondrial perturbations such as loss of respiration or drug treatment in a manner that we do not observe with other proteases.
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Affiliation(s)
- Meredith B Metzger
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA.
| | - Jessica L Scales
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Garis A Grant
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Abigail E Molnar
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Jadranka Loncarek
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Allan M Weissman
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA.
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15
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Hurtig JE, van Hoof A. An unknown essential function of tRNA splicing endonuclease is linked to the integrated stress response and intron debranching. Genetics 2023; 224:iyad044. [PMID: 36943791 PMCID: PMC10213494 DOI: 10.1093/genetics/iyad044] [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: 10/31/2022] [Revised: 10/31/2022] [Accepted: 03/09/2023] [Indexed: 03/23/2023] Open
Abstract
tRNA splicing endonuclease (TSEN) has a well-characterized role in transfer RNA (tRNA) splicing but also other functions. For yeast TSEN, these other functions include degradation of a subset of mRNAs that encode mitochondrial proteins and an unknown essential function. In this study, we use yeast genetics to characterize the unknown tRNA-independent function(s) of TSEN. Using a high-copy suppressor screen, we found that sen2 mutants can be suppressed by overexpression of SEN54. This effect was seen both for tRNA-dependent and tRNA-independent functions indicating that SEN54 is a general suppressor of sen2, likely through structural stabilization. A spontaneous suppressor screen identified mutations in the intron-debranching enzyme, Dbr1, as tRNA splicing-independent suppressors. Transcriptome analysis showed that sen2 mutation activates the Gcn4 stress response. These Gcn4 target transcripts decreased considerably in the sen2 dbr1 double mutant. We propose that Dbr1 and TSEN may compete for a shared substrate, which TSEN normally processes into an essential RNA, while Dbr1 initiates its degradation. These data provide further insight into the essential function(s) of TSEN. Importantly, single amino acid mutations in TSEN cause the generally fatal neuronal disease pontocerebellar hypoplasia (PCH). The mechanism by which defects in TSEN cause this disease is unknown, and our results reveal new possible mechanisms.
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Affiliation(s)
- Jennifer E Hurtig
- Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Ambro van Hoof
- Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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16
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Zheng Z, Han L, Li Y, Chen Z, Yang W, Liu C, Tao M, Jiang Y, Ke X, Liu Y, Guo X. Phospholipase A2-activating protein induces mitophagy trough anti-apoptotic MCL1-mediated NLRX1 oligomerization. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023:119487. [PMID: 37211156 DOI: 10.1016/j.bbamcr.2023.119487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/17/2023] [Accepted: 05/11/2023] [Indexed: 05/23/2023]
Abstract
Mitochondrial protein homeostasis is fine-tuned by diverse physiological processes such as mitochondria-associated degradation (MAD), which is regulated by valosin-containing protein (VCP) and its cofactors. As a cofactor of VCP, the mutation of phospholipase A-2-activating protein (PLAA) is the genetic cause of PLAA-associated neurodevelopmental disorder (PLAAND). However, the physiological and pathological roles of PLAA in mitochondria remain unclear. Here, we demonstrate that PLAA partially associates with mitochondria. Deficiency in PLAA increases mitochondrial reactive oxygen species (ROS) production, reduces mitochondrial membrane potential, inhibits mitochondrial respiratory activity and causes excessive mitophagy. Mechanically, PLAA interacts with myeloid cell leukemia-1 (MCL1) and facilitates its retro-translocation and proteasome-dependent degradation. The upregulation of MCL1 promotes the oligomerization of NLR family member X1 (NLRX1) and activation of mitophagy. Whereas downregulating NLRX1 abolishes MCL1 induced mitophagy. In summary, our data identify PLAA as a novel mediator of mitophagy by regulating MCL1-NLRX1 axis. We propose mitophagy as a target for therapeutic intervention in PLAAND.
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Affiliation(s)
- Zhilong Zheng
- Department of Neurobiology, Key Laboratory of Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Lu Han
- Department of Neurobiology, Key Laboratory of Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China; Child Mental Health Research Center, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yuanbo Li
- Department of Neurobiology, Key Laboratory of Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Zhen Chen
- Department of Neurobiology, Key Laboratory of Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Wangju Yang
- Department of Neurobiology, Key Laboratory of Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chunyue Liu
- Institute for Stem Cell and Neural Regeneration, State Key Laboratory of Reproductive Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Mengdan Tao
- Institute for Stem Cell and Neural Regeneration, State Key Laboratory of Reproductive Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yueqing Jiang
- Department of Neurobiology, Key Laboratory of Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaoyan Ke
- Child Mental Health Research Center, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
| | - Yan Liu
- Institute for Stem Cell and Neural Regeneration, State Key Laboratory of Reproductive Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China.
| | - Xing Guo
- Department of Neurobiology, Key Laboratory of Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China.
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17
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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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18
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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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19
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Meyer H, van den Boom J. Targeting of client proteins to the VCP/p97/Cdc48 unfolding machine. Front Mol Biosci 2023; 10:1142989. [PMID: 36825201 PMCID: PMC9941556 DOI: 10.3389/fmolb.2023.1142989] [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: 01/12/2023] [Accepted: 01/30/2023] [Indexed: 02/10/2023] Open
Abstract
The AAA+ ATPase p97 (also called VCP or Cdc48) is a major protein unfolding machine with hundreds of clients in diverse cellular pathways that are critical for cell homeostasis, proliferation and signaling. In this review, we summarize recent advances in understanding how diverse client proteins are targeted to the p97 machine to facilitate client degradation or to strip clients from binding partners for regulation. We describe an elaborate system that is governed by at least two types of alternative adapters. The Ufd1-Npl4 adapter along with accessory adapters targets ubiquitylated clients in the majority of pathways and uses ubiquitin as a universal unfolding tag. In contrast, the family of SEP-domain adapters such as p37 can target clients directly to p97 in a ubiquitin-independent manner. Despite the different targeting strategies, both pathways converge by inserting the client into the p97 pore to initiate a peptide threading mechanism through the central channel of p97 that drives client protein unfolding, protein extraction from membranes and protein complex disassembly processes.
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Affiliation(s)
- Hemmo Meyer
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
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20
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Severe heat stress modulated nuclear factor erythroid 2-related factor 2 and macrophage migration inhibitory factor pathway in rat liver. J Cell Commun Signal 2022; 16:547-566. [PMID: 35260968 PMCID: PMC9733776 DOI: 10.1007/s12079-022-00668-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 01/31/2022] [Indexed: 12/13/2022] Open
Abstract
Heat stress impairs physiology and overall functionality of the body at tissue and organ level in animals. Liver being a vital organ performs more than hundreds regulatory functions of the body. Present study investigates the modulation of molecular pathways that are responsible for liver damage triggered by heat stress. Male Sprague dawley rats were exposed to heat stress (45 °C) in heat simulation chamber till core temperature reaches 40 °C and 42 °C in 25 and 42 min respectively. For in-depth evaluation of liver functions during severe heat stress, hepatic transcriptome and proteome were analysed by microarray and two dimensional gel electrophoresis respectively. Results revealed major alterations in redox status, inflammation, mitochondrial dysfunction and proteostasis related pathways. Data of molecular pathway analysis demonstrate that nuclear factor erythroid 2-related factor 2 (NRF-2) mediated oxidative stress response and macrophage migration inhibitory factor (MIF) regulated inflammatory pathways were upregulated in severe heat stressed liver. Expression levels of downstream molecules of above pathways such as heat shock protein 90AB 1, peroxiredoxin 5, Jun N-terminal kinases 1/2, heme-oxygenase 1, apolipoprotein 1 and interleukin 10 were examined and result suggested the upregulation of these genes modulates the NRF-2 and MIF regulated pathways in heat stressed liver. Irregularity in molecular signalling networks lead to mitochondrial dysfunction indicated by upregulation of ATP synthase β and peroxiredoxin 1 along with decreased levels of glucose-6-phosphate dehydrogenase and enhanced activity of cytochrome c in liver mitochondria. Thus, current study demonstrated heat induced alterations in key liver functions were regulated by NRF-2 and MIF pathways.
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21
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Furutani N, Izawa S. Adaptability of wine yeast to ethanol-induced protein denaturation. FEMS Yeast Res 2022; 22:6831633. [PMID: 36385376 DOI: 10.1093/femsyr/foac059] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/28/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022] Open
Abstract
This year marks the 200th anniversary of the birth of Dr Louis Pasteur (1822-1895), who revealed that alcoholic fermentation is performed by yeast cells. Subsequently, details of the mechanisms of alcoholic fermentation and glycolysis in yeast cells have been elucidated. However, the mechanisms underlying the high tolerance and adaptability of yeast cells to ethanol are not yet fully understood. This review presents the response and adaptability of yeast cells to ethanol-induced protein denaturation. Herein, we describe the adverse effects of severe ethanol stress on intracellular proteins and the responses of yeast cells. Furthermore, recent findings on the acquired resistance of wine yeast cells to severe ethanol stress that causes protein denaturation are discussed, not only under laboratory conditions, but also during the fermentation process at 15°C to mimic the vinification process of white wine.
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Affiliation(s)
- Noboru Furutani
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan
| | - Shingo Izawa
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan
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22
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Papanagnou E, Gumeni S, Sklirou AD, Rafeletou A, Terpos E, Keklikoglou K, Kastritis E, Stamatelopoulos K, Sykiotis GP, Dimopoulos MA, Trougakos IP. Autophagy activation can partially rescue proteasome dysfunction-mediated cardiac toxicity. Aging Cell 2022; 21:e13715. [PMID: 36259256 PMCID: PMC9649605 DOI: 10.1111/acel.13715] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 08/01/2022] [Accepted: 08/31/2022] [Indexed: 01/25/2023] Open
Abstract
The ubiquitin-proteasome pathway and its functional interplay with other proteostatic and/or mitostatic modules are crucial for cell viability, especially in post-mitotic cells like cardiomyocytes, which are constantly exposed to proteotoxic, metabolic, and mechanical stress. Consistently, treatment of multiple myeloma patients with therapeutic proteasome inhibitors may induce cardiac failure; yet the effects promoted by heart-targeted proteasome dysfunction are not completely understood. We report here that heart-targeted proteasome knockdown in the fly experimental model results in increased proteome instability and defective mitostasis, leading to disrupted cardiac activity, systemic toxicity, and reduced longevity. These phenotypes were partially rescued by either heart targeted- or by dietary restriction-mediated activation of autophagy. Supportively, activation of autophagy by Rapamycin or Metformin administration in flies treated with proteasome inhibitors reduced proteome instability, partially restored mitochondrial function, mitigated cardiotoxicity, and improved flies' longevity. These findings suggest that autophagic inducers represent a novel promising intervention against proteasome inhibitor-induced cardiovascular complications.
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Affiliation(s)
- Eleni‐Dimitra Papanagnou
- Department of Cell Biology and Biophysics, Faculty of BiologyNational and Kapodistrian University of AthensAthensGreece
| | - Sentiljana Gumeni
- Department of Cell Biology and Biophysics, Faculty of BiologyNational and Kapodistrian University of AthensAthensGreece
| | - Aimilia D. Sklirou
- Department of Cell Biology and Biophysics, Faculty of BiologyNational and Kapodistrian University of AthensAthensGreece
| | - Alexandra Rafeletou
- Department of Cell Biology and Biophysics, Faculty of BiologyNational and Kapodistrian University of AthensAthensGreece
| | - Evangelos Terpos
- Department of Clinical Therapeutics, School of MedicineNational and Kapodistrian University of AthensAthensGreece
| | - Kleoniki Keklikoglou
- Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research (HCMR)CreteGreece,Biology DepartmentUniversity of CreteHeraklionGreece
| | - Efstathios Kastritis
- Department of Clinical Therapeutics, School of MedicineNational and Kapodistrian University of AthensAthensGreece
| | - Kimon Stamatelopoulos
- Department of Clinical Therapeutics, School of MedicineNational and Kapodistrian University of AthensAthensGreece
| | - Gerasimos P. Sykiotis
- Service of Endocrinology, Diabetology and MetabolismLausanne University Hospital and University of LausanneLausanneSwitzerland
| | - Meletios A. Dimopoulos
- Department of Clinical Therapeutics, School of MedicineNational and Kapodistrian University of AthensAthensGreece
| | - Ioannis P. Trougakos
- Department of Cell Biology and Biophysics, Faculty of BiologyNational and Kapodistrian University of AthensAthensGreece
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23
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Improper Proteostasis: Can It Serve as Biomarkers for Neurodegenerative Diseases? Mol Neurobiol 2022; 59:3382-3401. [PMID: 35305242 DOI: 10.1007/s12035-022-02775-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 02/19/2022] [Indexed: 10/18/2022]
Abstract
Cells synthesize new proteins after multiple molecular decisions. Damage of existing proteins, accumulation of abnormal proteins, and basic requirement of new proteins trigger protein quality control (PQC)-based alternative strategies to cope against proteostasis imbalance. Accumulation of misfolded proteins is linked with various neurodegenerative disorders. However, how deregulated components of this quality control system and their lack of general mechanism-based long-term changes can serve as biomarkers for neurodegeneration remains largely unexplored. Here, our article summarizes the chief findings, which may facilitate the search of novel and relevant proteostasis mechanism-based biomarkers associated with neuronal disorders. Understanding the abnormalities of PQC coupled molecules as possible biomarkers can help to determine neuronal fate and their contribution to the aetiology of several nervous system disorders.
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24
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Wang BB, Xu H, Isenmann S, Huang C, Elorza-Vidal X, Rychkov GY, Estévez R, Schittenhelm RB, Lukacs GL, Apaja PM. Ubr1-induced selective endophagy/autophagy protects against the endosomal and Ca 2+-induced proteostasis disease stress. Cell Mol Life Sci 2022; 79:167. [PMID: 35233680 PMCID: PMC8888484 DOI: 10.1007/s00018-022-04191-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/30/2022] [Accepted: 02/04/2022] [Indexed: 12/15/2022]
Abstract
The cellular defense mechanisms against cumulative endo-lysosomal stress remain incompletely understood. Here, we identify Ubr1 as a protein quality control (QC) E3 ubiquitin-ligase that counteracts proteostasis stresses by facilitating endosomal cargo-selective autophagy for lysosomal degradation. Astrocyte regulatory cluster membrane protein MLC1 mutations cause endosomal compartment stress by fusion and enlargement. Partial lysosomal clearance of mutant endosomal MLC1 is accomplished by the endosomal QC ubiquitin ligases, CHIP and Ubr1 via ESCRT-dependent route. As a consequence of the endosomal stress, a supportive QC mechanism, dependent on both Ubr1 and SQSTM1/p62 activities, targets ubiquitinated and arginylated MLC1 mutants for selective endosomal autophagy (endophagy). This QC pathway is also activated for arginylated Ubr1-SQSTM1/p62 autophagy cargoes during cytosolic Ca2+-assault. Conversely, the loss of Ubr1 and/or arginylation elicited endosomal compartment stress. These findings underscore the critical housekeeping role of Ubr1 and arginylation-dependent endophagy/autophagy during endo-lysosomal proteostasis perturbations and suggest a link of Ubr1 to Ca2+ homeostasis and proteins implicated in various diseases including cancers and brain disorders.
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Affiliation(s)
- Ben B Wang
- Lifelong Health, Organelle Proteostasis Diseases, South Australian Health and Medical Research Institute (SAHMRI), 5000 North Terrace, Adelaide, SA, 5000, Australia.,EMBL Australia, Adelaide, South Australia, 5000, Australia
| | - Haijin Xu
- Department of Physiology and Cell Information Systems, McGill University, 3655 Promenade Sir-William-Osler, Montréal, QC, H3G 1Y6, Canada
| | - Sandra Isenmann
- Lifelong Health, Organelle Proteostasis Diseases, South Australian Health and Medical Research Institute (SAHMRI), 5000 North Terrace, Adelaide, SA, 5000, Australia.,EMBL Australia, Adelaide, South Australia, 5000, Australia
| | - Cheng Huang
- Monash Biomedical Proteomics Facility, Department of Biochemistry, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Xabier Elorza-Vidal
- Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, L'Hospitalet de Llobregat, Universitat de Barcelona, Barcelona, Spain.,Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Grigori Y Rychkov
- Lifelong Health, Organelle Proteostasis Diseases, South Australian Health and Medical Research Institute (SAHMRI), 5000 North Terrace, Adelaide, SA, 5000, Australia.,School of Medicine, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Raúl Estévez
- Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, L'Hospitalet de Llobregat, Universitat de Barcelona, Barcelona, Spain.,Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Ralf B Schittenhelm
- Monash Biomedical Proteomics Facility, Department of Biochemistry, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Gergely L Lukacs
- Department of Physiology and Cell Information Systems, McGill University, 3655 Promenade Sir-William-Osler, Montréal, QC, H3G 1Y6, Canada. .,Department of Biochemistry, McGill University, Montréal, QC, H3G 1Y6, Canada.
| | - Pirjo M Apaja
- Lifelong Health, Organelle Proteostasis Diseases, South Australian Health and Medical Research Institute (SAHMRI), 5000 North Terrace, Adelaide, SA, 5000, Australia. .,EMBL Australia, Adelaide, South Australia, 5000, Australia. .,Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, 5005, Australia. .,College of Public Health and Medicine, Molecular Biosciences Theme, Flinders University, Bedford Park, SA, 5042, Australia.
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25
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Panda SP, Soni U. A review of dementia, focusing on the distinct roles of viral protein corona and MMP9 in dementia: Potential pharmacotherapeutic priorities. Ageing Res Rev 2022; 75:101560. [PMID: 35031512 DOI: 10.1016/j.arr.2022.101560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/27/2021] [Accepted: 01/07/2022] [Indexed: 02/08/2023]
Abstract
Dementia, in particular, is a defining feature of Alzheimer's and Parkinson's diseases. Because of the combination of motor and cognitive impairments, Parkinson's disease dementia (PDD) has a greater impact on affected people than Alzheimer's disease dementia (ADD) and others. If one family member develops dementia, the other members will suffer greatly in terms of social and occupational functioning. Currently, no relevant treatment is available based on an examination of the absolute pathophysiology of dementia. As a result, our objective of current review encouraged to look for dementia pharmacotherapy based on their pathogenesis. We systematically searched electronic databases such as PubMed, Scopus, and ESCI for information on the pathophysiology of demetia, as well as their treatment with allopathic and herbal medications. By modulating intermediate proteins, oxidative stress, viral protein corona, and MMP9 are etiological factors that cause dementia. The pathophysiology of ADD was described by two hypotheses: the amyloid cascade hypothesis and the tau and tangle hypothesis. ADD is caused by an increase in amyloid-beta (Aβ) and neurofibrillary tangles in the cerebrum. The viral protein corona (VPC) is more contagious and helps to form amyloid-beta (Aβ) plaques and neurofibrillary tangles in the cerebrum. Thioredoxin interacting protein (TXNIP) inside the BBB encourages Aβ to become more engaged. PDD is caused by decreased or absent dopamine secretion from nerve cells in the substantia nigra, as well as PRKN gene deletion/duplication mutations, and shift in the PRKN-PACRG organisation, all of which are linked to ageing. This article discussed the pathophysiology of dementia, as well as a list of herbal medications that can easily cross the BBB and have a therapeutic effect on dementia.
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26
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Borgert L, Mishra S, den Brave F. Quality control of cytoplasmic proteins inside the nucleus. Comput Struct Biotechnol J 2022; 20:4618-4625. [PMID: 36090811 PMCID: PMC9440239 DOI: 10.1016/j.csbj.2022.08.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 08/13/2022] [Accepted: 08/15/2022] [Indexed: 11/03/2022] Open
Abstract
A complex network of molecular chaperones and proteolytic machinery safeguards the proteins which comprise the proteome, from the time they are synthesized on ribosomes to their destruction via proteolysis. Impaired protein quality control results in the accumulation of aberrant proteins, which may undergo unwanted spurious interactions with other proteins, thereby interfering with a broad range of cellular functions. To protect the cellular environment, such proteins are degraded or sequestered into inclusions in different subcellular compartments. Recent findings demonstrate that aberrant or mistargeted proteins from different cytoplasmic compartments are removed from their environment by transporting them into the nucleus. These proteins are degraded by the nuclear ubiquitin–proteasome system or sequestered into intra-nuclear inclusions. Here, we discuss the emerging role of the nucleus as a cellular quality compartment based on recent findings in the yeast Saccharomyces cerevisiae. We describe the current knowledge on cytoplasmic substrates of nuclear protein quality control, the mechanism of nuclear import of such proteins, as well as possible advantages and risks of nuclear sequestration of aberrant proteins.
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27
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den Brave F, Gupta A, Becker T. Protein Quality Control at the Mitochondrial Surface. Front Cell Dev Biol 2021; 9:795685. [PMID: 34926473 PMCID: PMC8678412 DOI: 10.3389/fcell.2021.795685] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 11/05/2021] [Indexed: 12/14/2022] Open
Abstract
Mitochondria contain two membranes, the outer and inner membrane. The outer membrane fulfills crucial functions for the communication of mitochondria with the cellular environment like exchange of lipids via organelle contact sites, the transport of metabolites and the formation of a signaling platform in apoptosis and innate immunity. The translocase of the outer membrane (TOM complex) forms the entry gate for the vast majority of precursor proteins that are produced on cytosolic ribosomes. Surveillance of the functionality of outer membrane proteins is critical for mitochondrial functions and biogenesis. Quality control mechanisms remove defective and mistargeted proteins from the outer membrane as well as precursor proteins that clog the TOM complex. Selective degradation of single proteins is also an important mode to regulate mitochondrial dynamics and initiation of mitophagy pathways. Whereas inner mitochondrial compartments are equipped with specific proteases, the ubiquitin-proteasome system is a central player in protein surveillance on the mitochondrial surface. In this review, we summarize our current knowledge about the molecular mechanisms that govern quality control of proteins at the outer mitochondrial membrane.
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Affiliation(s)
- Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Arushi Gupta
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
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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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Mitochondrial Quality Control in the Maintenance of Cardiovascular Homeostasis: The Roles and Interregulation of UPS, Mitochondrial Dynamics and Mitophagy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:3960773. [PMID: 34804365 PMCID: PMC8601824 DOI: 10.1155/2021/3960773] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 09/20/2021] [Accepted: 10/24/2021] [Indexed: 12/20/2022]
Abstract
Maintenance of normal function of mitochondria is vital to the fate and health of cardiomyocytes. Mitochondrial quality control (MQC) mechanisms are essential in governing mitochondrial integrity and function. The ubiquitin-proteasome system (UPS), mitochondrial dynamics, and mitophagy are three major components of MQC. With the progress of research, our understanding of MQC mechanisms continues to deepen. Gradually, we realize that the three MQC mechanisms are not independent of each other. To the contrary, there are crosstalk among the mechanisms, which can make them interact with each other and cooperate well, forming a triangle interplay. Briefly, the UPS system can regulate the level of mitochondrial dynamic proteins and mitophagy receptors. In the process of Parkin-dependent mitophagy, the UPS is also widely activated, performing critical roles. Mitochondrial dynamics have a profound influence on mitophagy. In this review, we provide new processes of the three major MQC mechanisms in the background of cardiomyocytes and delve into the relationship between them.
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30
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Ibarra R, Borror HR, Hart B, Gardner RG, Kleiger G. The San1 Ubiquitin Ligase Avidly Recognizes Misfolded Proteins through Multiple Substrate Binding Sites. Biomolecules 2021; 11:1619. [PMID: 34827617 PMCID: PMC8615460 DOI: 10.3390/biom11111619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 02/06/2023] Open
Abstract
Cellular homeostasis depends on robust protein quality control (PQC) pathways that discern misfolded proteins from functional ones in the cell. One major branch of PQC involves the controlled degradation of misfolded proteins by the ubiquitin-proteasome system. Here ubiquitin ligases must recognize and bind to misfolded proteins with sufficient energy to form a complex and with an adequate half-life to achieve poly-ubiquitin chain formation, the signal for protein degradation, prior to its dissociation from the ligase. It is not well understood how PQC ubiquitin ligases accomplish these tasks. Employing a fully reconstituted enzyme and substrate system to perform quantitative biochemical experiments, we demonstrate that the yeast PQC ubiquitin ligase San1 contains multiple substrate binding sites along its polypeptide chain that appear to display specificity for unique misfolded proteins. The results are consistent with a model where these substrate binding sites enable San1 to bind to misfolded substrates avidly, resulting in high affinity ubiquitin ligase-substrate complexes.
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Affiliation(s)
- Rebeca Ibarra
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, NV 89154, USA; (R.I.); (B.H.)
| | - Heather R. Borror
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; (H.R.B.); (R.G.G.)
| | - Bryce Hart
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, NV 89154, USA; (R.I.); (B.H.)
| | - Richard G. Gardner
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; (H.R.B.); (R.G.G.)
| | - Gary Kleiger
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, NV 89154, USA; (R.I.); (B.H.)
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31
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Franz A, Valledor P, Ubieto-Capella P, Pilger D, Galarreta A, Lafarga V, Fernández-Llorente A, de la Vega-Barranco G, den Brave F, Hoppe T, Fernandez-Capetillo O, Lecona E. USP7 and VCP FAF1 define the SUMO/Ubiquitin landscape at the DNA replication fork. Cell Rep 2021; 37:109819. [PMID: 34644576 PMCID: PMC8527565 DOI: 10.1016/j.celrep.2021.109819] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/20/2021] [Accepted: 09/21/2021] [Indexed: 12/16/2022] Open
Abstract
The AAA+ ATPase VCP regulates the extraction of SUMO and ubiquitin-modified DNA replication factors from chromatin. We have previously described that active DNA synthesis is associated with a SUMO-high/ubiquitin-low environment governed by the deubiquitylase USP7. Here, we unveil a functional cooperation between USP7 and VCP in DNA replication, which is conserved from Caenorhabditis elegans to mammals. The role of VCP in chromatin is defined by its cofactor FAF1, which facilitates the extraction of SUMOylated and ubiquitylated proteins that accumulate after the block of DNA replication in the absence of USP7. The inactivation of USP7 and FAF1 is synthetically lethal both in C. elegans and mammalian cells. In addition, USP7 and VCP inhibitors display synergistic toxicity supporting a functional link between deubiquitylation and extraction of chromatin-bound proteins. Our results suggest that USP7 and VCPFAF1 facilitate DNA replication by controlling the balance of SUMO/Ubiquitin-modified DNA replication factors on chromatin.
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Affiliation(s)
- André Franz
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
| | - Pablo Valledor
- Genomic Instability Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Patricia Ubieto-Capella
- Genomic Instability Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Domenic Pilger
- The Wellcome Trust and Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Antonio Galarreta
- Genomic Instability Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Vanesa Lafarga
- Genomic Instability Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Alejandro Fernández-Llorente
- Chromatin, Cancer and the Ubiquitin System lab, Centre for Molecular Biology Severo Ochoa (CBMSO, CSIC-UAM), Department of Genome Dynamics and Function, Madrid 28049, Spain
| | - Guillermo de la Vega-Barranco
- Chromatin, Cancer and the Ubiquitin System lab, Centre for Molecular Biology Severo Ochoa (CBMSO, CSIC-UAM), Department of Genome Dynamics and Function, Madrid 28049, Spain
| | - Fabian den Brave
- Institute of Biochemistry and Molecular Biology, University of Bonn, 53115 Bonn, Germany
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
| | - Oscar Fernandez-Capetillo
- Genomic Instability Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain; Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 21 Stockholm, Sweden.
| | - Emilio Lecona
- Chromatin, Cancer and the Ubiquitin System lab, Centre for Molecular Biology Severo Ochoa (CBMSO, CSIC-UAM), Department of Genome Dynamics and Function, Madrid 28049, Spain.
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32
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Powell M, Blaskovich MAT, Hansford KA. Targeted Protein Degradation: The New Frontier of Antimicrobial Discovery? ACS Infect Dis 2021; 7:2050-2067. [PMID: 34259518 DOI: 10.1021/acsinfecdis.1c00203] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Targeted protein degradation aims to hijack endogenous protein quality control systems to achieve direct knockdown of protein targets. This exciting technology utilizes event-based pharmacology to produce therapeutic outcomes, a feature that distinguishes it from classical occupancy-based inhibitor agents. Early degrader candidates display resilience to mutations while possessing potent nanomolar activity and high target specificity. Paired with the rapid advancement of our knowledge in the factors driving targeted degradation, the expansion of this style of therapeutic agent to a range of disease indications is eagerly awaited. In particular, the area of antibiotic discovery is sorely lacking in novel approaches, with the Antimicrobial Resistance (AMR) crisis looming as the next potential global health calamity. Here, the current advances in targeted protein degradation are highlighted, and potential approaches for designing novel antimicrobial protein degraders are proposed, ranging from adaptations of current strategies to completely novel approaches to targeted protein degradation.
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Affiliation(s)
- Matthew Powell
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Mark A. T. Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Karl A. Hansford
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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33
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Dederer V, Lemberg MK. Transmembrane dislocases: a second chance for protein targeting. Trends Cell Biol 2021; 31:898-911. [PMID: 34147299 DOI: 10.1016/j.tcb.2021.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/11/2021] [Accepted: 05/14/2021] [Indexed: 12/31/2022]
Abstract
Precise distribution of proteins is essential to sustain the viability of cells. A complex network of protein synthesis and targeting factors cooperate with protein quality control systems to ensure protein homeostasis. Defective proteins are inevitably degraded by the ubiquitin-proteasome system and lysosomes. However, due to overlapping targeting information and limited targeting fidelity, certain proteins become mislocalized. In this review, we present the idea that transmembrane dislocases recognize and remove mislocalized membrane proteins from cellular organelles. This enables other targeting attempts and prevents degradation of mislocalized but otherwise functional proteins. These transmembrane dislocases can be found in the outer mitochondrial membrane (OMM) and endoplasmic reticulum (ER). We highlight common principles regarding client recognition and outline open questions in our understanding of transmembrane dislocases.
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Affiliation(s)
- Verena Dederer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Current address: Institute for Pharmaceutical Biology and Buchmann Institute for Molecular Life Science, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Cologne, Germany.
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34
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Sharma J, Kumari R, Bhargava A, Tiwari R, Mishra PK. Mitochondrial-induced Epigenetic Modifications: From Biology to Clinical Translation. Curr Pharm Des 2021; 27:159-176. [PMID: 32851956 DOI: 10.2174/1381612826666200826165735] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/27/2020] [Indexed: 11/22/2022]
Abstract
Mitochondria are maternally inherited semi-autonomous organelles that play a central role in redox balance, energy metabolism, control of integrated stress responses, and cellular homeostasis. The molecular communication between mitochondria and the nucleus is intricate and bidirectional in nature. Though mitochondrial genome encodes for several key proteins involved in oxidative phosphorylation, several regulatory factors encoded by nuclear DNA are prominent contributors to mitochondrial biogenesis and function. The loss of synergy between this reciprocal control of anterograde (nuclear to mitochondrial) and retrograde (mitochondrial to nuclear) signaling, triggers epigenomic imbalance and affects mitochondrial function and global gene expressions. Recent expansions of our knowledge on mitochondrial epigenomics have offered novel perspectives for the study of several non-communicable diseases including cancer. As mitochondria are considered beacons for pharmacological interventions, new frontiers in targeted delivery approaches could provide opportunities for effective disease management and cure through reversible epigenetic reprogramming. This review focuses on recent progress in the area of mitochondrial-nuclear cross-talk and epigenetic regulation of mitochondrial DNA methylation, mitochondrial micro RNAs, and post-translational modification of mitochondrial nucleoid-associated proteins that hold major opportunities for targeted drug delivery and clinical translation.
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Affiliation(s)
- Jahnavi Sharma
- Department of Molecular Biology, ICMR-National Institute for Research in Environmental Health, Bhopal, India
| | - Roshani Kumari
- Department of Molecular Biology, ICMR-National Institute for Research in Environmental Health, Bhopal, India
| | - Arpit Bhargava
- Department of Molecular Biology, ICMR-National Institute for Research in Environmental Health, Bhopal, India
| | - Rajnarayan Tiwari
- Department of Molecular Biology, ICMR-National Institute for Research in Environmental Health, Bhopal, India
| | - Pradyumna K Mishra
- Department of Molecular Biology, ICMR-National Institute for Research in Environmental Health, Bhopal, India
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35
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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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36
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MITOL-dependent ubiquitylation negatively regulates the entry of PolγA into mitochondria. PLoS Biol 2021; 19:e3001139. [PMID: 33657094 PMCID: PMC7959396 DOI: 10.1371/journal.pbio.3001139] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 03/15/2021] [Accepted: 02/04/2021] [Indexed: 02/01/2023] Open
Abstract
Mutations in mitochondrial replicative polymerase PolγA lead to progressive external ophthalmoplegia (PEO). While PolγA is the known central player in mitochondrial DNA (mtDNA) replication, it is unknown whether a regulatory process exists on the mitochondrial outer membrane which controlled its entry into the mitochondria. We now demonstrate that PolγA is ubiquitylated by mitochondrial E3 ligase, MITOL (or MARCH5, RNF153). Ubiquitylation in wild-type (WT) PolγA occurs at Lysine 1060 residue via K6 linkage. Ubiquitylation of PolγA negatively regulates its binding to Tom20 and thereby its mitochondrial entry. While screening different PEO patients for mitochondrial entry, we found that a subset of the PolγA mutants is hyperubiquitylated by MITOL and interact less with Tom20. These PolγA variants cannot enter into mitochondria, instead becomes enriched in the insoluble fraction and undergo enhanced degradation. Hence, mtDNA replication, as observed via BrdU incorporation into the mtDNA, was compromised in these PEO mutants. However, by manipulating their ubiquitylation status by 2 independent techniques, these PEO mutants were reactivated, which allowed the incorporation of BrdU into mtDNA. Thus, regulated entry of non-ubiquitylated PolγA may have beneficial consequences for certain PEO patients. This study shows that mitochondrial entry of the replicative polymerase PolgA is regulated by ubiquitylation by the E3 ligase MITOL; however, by manipulating their ubiquitylation status, some progressive external ophthalmoplegia mutants whose PolgA is polyubiquitylated and cannot enter the mitochondrion can be reactivated and hence become functionally active.
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37
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Yang Y, Hu Y, Wu L, Zhang P, Shang J. dnm1 deletion blocks mitochondrial fragmentation in Δfzo1 cells. Yeast 2021; 38:197-205. [PMID: 33125774 DOI: 10.1002/yea.3524] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/21/2020] [Accepted: 09/30/2020] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial division and fusion play critical roles in maintaining functional mitochondria. Fzo1 is an outer mitochondrial membrane GTPase that played an essential role in mitochondrial fusion in budding yeast Saccharomyces cerevisiae. Here, we report the characterization of the Schizosaccharomyces pombe homologue of S. cerevisiae Fzo1p, Fzo1. Disruption of the fzo1 gene in S. pombe results in a fragmented mitochondrial morphology and a dramatically reduced growth on glycerol medium phenotype, indicating that deletion of fzo1 compromises respiratory function. Fluorescence microscopy shows that Fzo1p is located in the mitochondria. Overexpressing Fzo1 from a heterologous promoter induces mitochondrial aggregation. We also find that dnm1 mutations could both block mitochondrial fragmentation and rescue respiration growth defect in Δfzo1 single mutant cells. Our results proposed that a genetic interaction between fzo1 and a balance between division- and fusion-controlled mitochondrial shape and function in S. pombe. This study represents the first report of Fzo1 mediator of mitochondrial fusion in S. pombe.
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Affiliation(s)
- Yanmei Yang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Rd., Nanjing, 210023, China
| | - Yinzhi Hu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Rd., Nanjing, 210023, China
| | - Lin Wu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Rd., Nanjing, 210023, China
| | - Pan Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Rd., Nanjing, 210023, China
| | - Jinjie Shang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Rd., Nanjing, 210023, China
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38
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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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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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Singh A, Vashistha N, Heck J, Tang X, Wipf P, Brodsky JL, Hampton RY. Direct involvement of Hsp70 ATP hydrolysis in Ubr1-dependent quality control. Mol Biol Cell 2020; 31:2669-2686. [PMID: 32966159 PMCID: PMC7927186 DOI: 10.1091/mbc.e20-08-0541] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Chaperones can mediate both protein folding and degradation. This process is referred to as protein triage, which demands study to reveal mechanisms of quality control for both basic scientific and translational purposes. In yeast, many misfolded proteins undergo chaperone-dependent ubiquitination by the action of the E3 ligases Ubr1 and San1, allowing detailed study of protein triage. In cells, both HSP70 and HSP90 mediated substrate ubiquitination, and the canonical ATP cycle was required for HSP70’s role: we have found that ATP hydrolysis by HSP70, the nucleotide exchange activity of Sse1, and the action of J-proteins are all needed for Ubr1-mediated quality control. To discern whether chaperones were directly involved in Ubr1-mediated ubiquitination, we developed a bead-based assay with covalently immobilized but releasable misfolded protein to obviate possible chaperone effects on substrate physical state or transport. In this in vitro assay, only HSP70 was required, along with its ATPase cycle and relevant cochaperones, for Ubr1-mediated ubiquitination. The requirement for the HSP70 ATP cycle in ubiquitination suggests a possible model of triage in which efficiently folded proteins are spared, while slow-folding or nonfolding proteins are iteratively tagged with ubiquitin for subsequent degradation.
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Affiliation(s)
- Amanjot Singh
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92103
| | - Nidhi Vashistha
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92103
| | - Jarrod Heck
- Adaptive Biotechnologies Corp., Seattle, WA 98102
| | - Xin Tang
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92103
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260
| | - Randolph Y Hampton
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92103
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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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