1
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Arie M, Matzov D, Karmona R, Szenkier N, Stanhill A, Navon A. A non-symmetrical p97 conformation initiates a multistep recruitment of Ufd1/Npl4. iScience 2024; 27:110061. [PMID: 38947518 PMCID: PMC11214410 DOI: 10.1016/j.isci.2024.110061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/10/2024] [Accepted: 05/17/2024] [Indexed: 07/02/2024] Open
Abstract
In vitro experiments and cryo-EM structures of p97 and its cofactor, Ufd1/Npl4 (UN), elucidated substrate processing. Yet, the structural transitions and the related ATPase cycle upon UN binding remain unresolved. We captured two discrete conformations: One in which D1 protomers are ATP bound, while the D2 subunits are in the ADP state, presumably required for substrate engagement with the D2 pore; and a heterologous nucleotide state within the D1 ring in which only two NTDs are in the "up" ATP state that favors UN binding. Further analysis suggests that initially, UN binds p97's non-symmetrical conformation, this association promotes a structural transition upon which five NTDs shift to an "up" state and are poised to bind ATP. The UBXL domain of Npl4 was captured bound to an NTD in the ADP state, demonstrating a conformation that may provide directionality to incoming substrate and introduce the flexibility needed for substrate processing.
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Affiliation(s)
- Michal Arie
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Donna Matzov
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Rotem Karmona
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Natalia Szenkier
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ariel Stanhill
- Department of Natural Sciences, The Open University of Israel, Raanana 4353701, Israel
| | - Ami Navon
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
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2
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Jones NH, Liu Q, Urnavicius L, Dahan NE, Vostal LE, Kapoor TM. Allosteric activation of VCP, an AAA unfoldase, by small molecule mimicry. Proc Natl Acad Sci U S A 2024; 121:e2316892121. [PMID: 38833472 PMCID: PMC11181084 DOI: 10.1073/pnas.2316892121] [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: 10/02/2023] [Accepted: 04/17/2024] [Indexed: 06/06/2024] Open
Abstract
The loss of function of AAA (ATPases associated with diverse cellular activities) mechanoenzymes has been linked to diseases, and small molecules that activate these proteins can be powerful tools to probe mechanisms and test therapeutic hypotheses. Unlike chemical inhibitors that can bind a single conformational state to block enzyme function, activator binding must be permissive to different conformational states needed for mechanochemistry. However, we do not know how AAA proteins can be activated by small molecules. Here, we focus on valosin-containing protein (VCP)/p97, an AAA unfoldase whose loss of function has been linked to protein aggregation-based disorders, to identify druggable sites for chemical activators. We identified VCP ATPase Activator 1 (VAA1), a compound that dose-dependently stimulates VCP ATPase activity up to ~threefold. Our cryo-EM studies resulted in structures (ranging from ~2.9 to 3.7 Å-resolution) of VCP in apo and ADP-bound states and revealed that VAA1 binds an allosteric pocket near the C-terminus in both states. Engineered mutations in the VAA1-binding site confer resistance to VAA1, and furthermore, modulate VCP activity. Mutation of a phenylalanine residue in the VCP C-terminal tail that can occupy the VAA1 binding site also stimulates ATPase activity, suggesting that VAA1 acts by mimicking this interaction. Together, our findings uncover a druggable allosteric site and a mechanism of enzyme regulation that can be tuned through small molecule mimicry.
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Affiliation(s)
- Natalie H. Jones
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY10065
- Tri-Institutional PhD Program in Chemical Biology, New York, NY10065
| | - Qiwen Liu
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY10065
| | - Linas Urnavicius
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY10065
| | - Noa E. Dahan
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY10065
- The David Rockefeller Graduate Program in Bioscience, The Rockefeller University, New York, NY10065
| | - Lauren E. Vostal
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY10065
- Tri-Institutional PhD Program in Chemical Biology, New York, NY10065
| | - Tarun M. Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY10065
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3
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Phan JM, Creekmore BC, Nguyen AT, Bershadskaya DD, Darwich NF, Mann CN, Lee EB. VCP activator reverses nuclear proteostasis defects and enhances TDP-43 aggregate clearance in multisystem proteinopathy models. J Clin Invest 2024; 134:e169039. [PMID: 38787785 PMCID: PMC11257039 DOI: 10.1172/jci169039] [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: 01/20/2023] [Accepted: 05/17/2024] [Indexed: 05/26/2024] Open
Abstract
Pathogenic variants in valosin-containing protein (VCP) cause multisystem proteinopathy (MSP), a disease characterized by multiple clinical phenotypes including inclusion body myopathy, Paget's disease of the bone, and frontotemporal dementia (FTD). How such diverse phenotypes are driven by pathogenic VCP variants is not known. We found that these diseases exhibit a common pathologic feature: ubiquitinated intranuclear inclusions affecting myocytes, osteoclasts, and neurons. Moreover, knock-in cell lines harboring MSP variants show a reduction in nuclear VCP. Given that MSP is associated with neuronal intranuclear inclusions comprised of TDP-43 protein, we developed a cellular model whereby proteostatic stress results in the formation of insoluble intranuclear TDP-43 aggregates. Consistent with a loss of nuclear VCP function, cells harboring MSP variants or cells treated with VCP inhibitor exhibited decreased clearance of insoluble intranuclear TDP-43 aggregates. Moreover, we identified 4 compounds that activate VCP primarily by increasing D2 ATPase activity, where pharmacologic VCP activation appears to enhance clearance of insoluble intranuclear TDP-43 aggregate. Our findings suggest that VCP function is important for nuclear protein homeostasis, that impaired nuclear proteostasis may contribute to MSP, and that VCP activation may be a potential therapeutic by virtue of enhancing the clearance of intranuclear protein aggregates.
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4
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Pontifex CS, Zaman M, Fanganiello RD, Shutt TE, Pfeffer G. Valosin-Containing Protein (VCP): A Review of Its Diverse Molecular Functions and Clinical Phenotypes. Int J Mol Sci 2024; 25:5633. [PMID: 38891822 PMCID: PMC11172259 DOI: 10.3390/ijms25115633] [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: 03/19/2024] [Revised: 05/20/2024] [Accepted: 05/20/2024] [Indexed: 06/21/2024] Open
Abstract
In this review we examine the functionally diverse ATPase associated with various cellular activities (AAA-ATPase), valosin-containing protein (VCP/p97), its molecular functions, the mutational landscape of VCP and the phenotypic manifestation of VCP disease. VCP is crucial to a multitude of cellular functions including protein quality control, endoplasmic reticulum-associated degradation (ERAD), autophagy, mitophagy, lysophagy, stress granule formation and clearance, DNA replication and mitosis, DNA damage response including nucleotide excision repair, ATM- and ATR-mediated damage response, homologous repair and non-homologous end joining. VCP variants cause multisystem proteinopathy, and pathology can arise in several tissue types such as skeletal muscle, bone, brain, motor neurons, sensory neurons and possibly cardiac muscle, with the disease course being challenging to predict.
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Affiliation(s)
- Carly S. Pontifex
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (C.S.P.); (M.Z.); (T.E.S.)
| | - Mashiat Zaman
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (C.S.P.); (M.Z.); (T.E.S.)
- Alberta Child Health Research Institute, Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 1N4, Canada
| | | | - Timothy E. Shutt
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (C.S.P.); (M.Z.); (T.E.S.)
- Alberta Child Health Research Institute, Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Gerald Pfeffer
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (C.S.P.); (M.Z.); (T.E.S.)
- Alberta Child Health Research Institute, Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
- Heritage Medical Research Building 155, 3330 Hospital Dr NW, Calgary, AB T2N 4N1, Canada
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5
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Batra S, Vaquer-Alicea JI, Valdez C, Taylor SP, Manon VA, Vega AR, Kashmer OM, Kolay S, Lemoff A, Cairns NJ, White CL, Diamond MI. VCP regulates early tau seed amplification via specific cofactors. RESEARCH SQUARE 2024:rs.3.rs-4307848. [PMID: 38826306 PMCID: PMC11142303 DOI: 10.21203/rs.3.rs-4307848/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Background Neurodegenerative tauopathies may progress based on seeding by pathological tau assemblies, whereby an aggregate is released from one cell, gains entry to an adjacent or connected cell, and serves as a specific template for its own replication in the cytoplasm. In vitro seeding reactions typically take days, yet seeding into the complex cytoplasmic milieu happens within hours, implicating a machinery with unknown players that controls this process in the acute phase. Methods We used proximity labeling to identify factors that control seed amplification within 5h of seed exposure. We fused split-APEX2 to the C-terminus of tau repeat domain (RD) to reconstitute peroxidase activity 5h after seeded intracellular tau aggregation. Valosin containing protein (VCP/p97) was the top hit. VCP harbors dominant mutations that underlie two neurodegenerative diseases, multisystem proteinopathy and vacuolar tauopathy, but its mechanistic role is unclear. We used immortalized cells and human neurons to study the effects of VCP on tau seeding. We exposed cells to fibrils or brain homogenates in cell culture media and measured effects on uptake and induction of intracellular tau aggregation following various genetic and chemical manipulations of VCP. Results VCP knockdown reduced tau seeding. Chemical inhibitors had opposing effects on aggregation in HEK293T tau biosensor cells and human neurons alike: ML-240 increased seeding efficiency, whereas NMS-873 decreased it. The inhibitors were effective only when administered within 8h of seed exposure, indicating a role for VCP early in seed processing. We screened 30 VCP co-factors in HEK293T biosensor cells by genetic knockout or knockdown. Reduction of ATXN3, NSFL1C, UBE4B, NGLY1, and OTUB1 decreased tau seeding, as did NPLOC4, which also uniquely increased soluble tau levels. By contrast, reduction of FAF2 increased tau seeding. Conclusions Divergent effects on tau seeding of chemical inhibitors and cofactor reduction indicate that VCP regulates this process. This is consistent with a dedicated cytoplasmic processing complex based on VCP that directs seeds acutely towards degradation vs. amplification.
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Affiliation(s)
- Sushobhna Batra
- UT Southwestern: The University of Texas Southwestern Medical Center
| | | | - Clarissa Valdez
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Skyler P Taylor
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Victor A Manon
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Anthony R Vega
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Omar M Kashmer
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Sourav Kolay
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Andrew Lemoff
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Nigel J Cairns
- University of Exeter Faculty of Health and Life Sciences
| | - Charles L White
- UT Southwestern: The University of Texas Southwestern Medical Center
| | - Marc I Diamond
- UT Southwestern: The University of Texas Southwestern Medical Center
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6
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Wrobel L, Hoffmann JL, Li X, Rubinsztein DC. p37 regulates VCP/p97 shuttling and functions in the nucleus and cytosol. SCIENCE ADVANCES 2024; 10:eadl6082. [PMID: 38701207 PMCID: PMC11068011 DOI: 10.1126/sciadv.adl6082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/02/2024] [Indexed: 05/05/2024]
Abstract
The AAA+-ATPase valosin-containing protein (VCP; also called p97 or Cdc48), a major protein unfolding machinery with a variety of essential functions, localizes to different subcellular compartments where it has different functions. However, the processes regulating the distribution of VCP between the cytosol and nucleus are not understood. Here, we identified p37 (also called UBXN2B) as a major factor regulating VCP nucleocytoplasmic shuttling. p37-dependent VCP localization was crucial for local cytosolic VCP functions, such as autophagy, and nuclear functions in DNA damage repair. Mutations in VCP causing multisystem proteinopathy enhanced its association with p37, leading to decreased nuclear localization of VCP, which enhanced susceptibility to DNA damage accumulation. Both VCP localization and DNA damage susceptibility in cells with such mutations were normalized by lowering p37 levels. Thus, we uncovered a mechanism by which VCP nucleocytoplasmic distribution is fine-tuned, providing a means for VCP to respond appropriately to local needs.
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Affiliation(s)
- Lidia Wrobel
- Department of Medical Genetics, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
- UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Johanna L. Hoffmann
- Department of Medical Genetics, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
- UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Xinyi Li
- Department of Medical Genetics, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
- UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - David C. Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
- UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
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7
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Klickstein JA, Johnson MA, Antonoudiou P, Maguire J, Paulo JA, Gygi SP, Weihl C, Raman M. ALS-related p97 R155H mutation disrupts lysophagy in iPSC-derived motor neurons. Stem Cell Reports 2024; 19:366-382. [PMID: 38335961 PMCID: PMC10937112 DOI: 10.1016/j.stemcr.2024.01.002] [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: 07/11/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 02/12/2024] Open
Abstract
Mutations in the AAA+ ATPase p97 cause multisystem proteinopathy 1, which includes amyotrophic lateral sclerosis; however, the pathogenic mechanisms that contribute to motor neuron loss remain obscure. Here, we use two induced pluripotent stem cell models differentiated into spinal motor neurons to investigate how p97 mutations perturb the motor neuron proteome. Using quantitative proteomics, we find that motor neurons harboring the p97 R155H mutation have deficits in the selective autophagy of lysosomes (lysophagy). p97 R155H motor neurons are unable to clear damaged lysosomes and have reduced viability. Lysosomes in mutant motor neurons have increased pH compared with wild-type cells. The clearance of damaged lysosomes involves UBXD1-p97 interaction, which is disrupted in mutant motor neurons. Finally, inhibition of the ATPase activity of p97 using the inhibitor CB-5083 rescues lysophagy defects in mutant motor neurons. These results add to the evidence that endo-lysosomal dysfunction is a key aspect of disease pathogenesis in p97-related disorders.
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Affiliation(s)
- Jacob A Klickstein
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA
| | - Michelle A Johnson
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA
| | | | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Steve P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Chris Weihl
- Department of Neurology, Washington University at St. Louis, St. Louis, MO
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA.
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8
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Mah-Som AY, Daw J, Huynh D, Wu M, Creekmore BC, Burns W, Skinner SA, Holla ØL, Smeland MF, Planes M, Uguen K, Redon S, Bierhals T, Scholz T, Denecke J, Mensah MA, Sczakiel HL, Tichy H, Verheyen S, Blatterer J, Schreiner E, Thies J, Lam C, Spaeth CG, Pena L, Ramsey K, Narayanan V, Seaver LH, Rodriguez D, Afenjar A, Burglen L, Lee EB, Chou TF, Weihl CC, Shinawi MS. An autosomal-dominant childhood-onset disorder associated with pathogenic variants in VCP. Am J Hum Genet 2023; 110:1959-1975. [PMID: 37883978 PMCID: PMC10645565 DOI: 10.1016/j.ajhg.2023.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 10/06/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023] Open
Abstract
Valosin-containing protein (VCP) is an AAA+ ATPase that plays critical roles in multiple ubiquitin-dependent cellular processes. Dominant pathogenic variants in VCP are associated with adult-onset multisystem proteinopathy (MSP), which manifests as myopathy, bone disease, dementia, and/or motor neuron disease. Through GeneMatcher, we identified 13 unrelated individuals who harbor heterozygous VCP variants (12 de novo and 1 inherited) associated with a childhood-onset disorder characterized by developmental delay, intellectual disability, hypotonia, and macrocephaly. Trio exome sequencing or a multigene panel identified nine missense variants, two in-frame deletions, one frameshift, and one splicing variant. We performed in vitro functional studies and in silico modeling to investigate the impact of these variants on protein function. In contrast to MSP variants, most missense variants had decreased ATPase activity, and one caused hyperactivation. Other variants were predicted to cause haploinsufficiency, suggesting a loss-of-function mechanism. This cohort expands the spectrum of VCP-related disease to include neurodevelopmental disease presenting in childhood.
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Affiliation(s)
- Annelise Y Mah-Som
- Genetics Training Program, Harvard Medical School and Brigham & Women's Hospital, Boston, MA 02115, USA; Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jil Daw
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Diana Huynh
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mengcheng Wu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Benjamin C Creekmore
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | | | | | - Øystein L Holla
- Department of Medical Genetics, Telemark Hospital, 3710 Skien, Norway
| | - Marie F Smeland
- Department of Pediatric Rehabilitation, University Hospital of North Norway and the Arctic, University of Norway, 9019 Tromsø, Norway
| | - Marc Planes
- Service de Génétique Médicale et Biologie de la Reproduction, and Centre de Référence Déficiences Intellectuelles, Service de Pédiatrie, CHU de Brest, 29200 Brest, France
| | - Kevin Uguen
- Service de Génétique Médicale et Biologie de la Reproduction, and Centre de Référence Déficiences Intellectuelles, Service de Pédiatrie, CHU de Brest, 29200 Brest, France; University Brest, Inserm, EFS, UMR 1078, GGB, 29200 Brest, France
| | - Sylvia Redon
- Service de Génétique Médicale et Biologie de la Reproduction, and Centre de Référence Déficiences Intellectuelles, Service de Pédiatrie, CHU de Brest, 29200 Brest, France; University Brest, Inserm, EFS, UMR 1078, GGB, 29200 Brest, France
| | - Tatjana Bierhals
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Tasja Scholz
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Jonas Denecke
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Martin A Mensah
- Institute of Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany; BIH Biomedical Innovation Academy, Berlin Institute of Health at Charité - Universitätsmedizin Berlin, 10117 Berlin, Germany; RG Development and Disease, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Henrike L Sczakiel
- Institute of Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany; BIH Biomedical Innovation Academy, Berlin Institute of Health at Charité - Universitätsmedizin Berlin, 10117 Berlin, Germany; RG Development and Disease, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Heidelis Tichy
- Institute of Human Genetics, Diagnostic and Research Center for Molecular BioMedicine, Medical University of Graz, 8010 Graz, Austria
| | - Sarah Verheyen
- Institute of Human Genetics, Diagnostic and Research Center for Molecular BioMedicine, Medical University of Graz, 8010 Graz, Austria
| | - Jasmin Blatterer
- Institute of Human Genetics, Diagnostic and Research Center for Molecular BioMedicine, Medical University of Graz, 8010 Graz, Austria
| | - Elisabeth Schreiner
- Institute of Human Genetics, Diagnostic and Research Center for Molecular BioMedicine, Medical University of Graz, 8010 Graz, Austria
| | - Jenny Thies
- Division of Genetic Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Christina Lam
- Division of Genetic Medicine, Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98105, USA
| | - Christine G Spaeth
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Loren Pena
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Keri Ramsey
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ 85004, USA
| | - Vinodh Narayanan
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ 85004, USA
| | - Laurie H Seaver
- Corewell Health Helen Devos Children's Hospital, Department of Pediatrics and Human Development, Michigan State University College of Human Medicine, Grand Rapids, MI 49503, USA
| | - Diana Rodriguez
- Departement of Pediatric Neurology & Reference Centre for Congenital Malformations and Diseases of the Cerebellum, AP-HP.Sorbonne Université - Hôpital d'Enfants Armand-Trousseau, 75012 Paris, France
| | - Alexandra Afenjar
- Cerebellar Malformations and Congenital Diseases Reference Center and Neurogenetics Lab, Department of Genetics, Armand Trousseau Hospital, AP-HP Sorbonne Université, 75006 Paris, France
| | - Lydie Burglen
- Cerebellar Malformations and Congenital Diseases Reference Center and Neurogenetics Lab, Department of Genetics, Armand Trousseau Hospital, AP-HP Sorbonne Université, 75006 Paris, France
| | - Edward B Lee
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Conrad C Weihl
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Marwan S Shinawi
- Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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9
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Braxton JR, Southworth DR. Structural insights of the p97/VCP AAA+ ATPase: How adapter interactions coordinate diverse cellular functionality. J Biol Chem 2023; 299:105182. [PMID: 37611827 PMCID: PMC10641518 DOI: 10.1016/j.jbc.2023.105182] [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: 05/30/2023] [Revised: 08/05/2023] [Accepted: 08/14/2023] [Indexed: 08/25/2023] Open
Abstract
p97/valosin-containing protein is an essential eukaryotic AAA+ ATPase with diverse functions including protein homeostasis, membrane remodeling, and chromatin regulation. Dysregulation of p97 function causes severe neurodegenerative disease and is associated with cancer, making this protein a significant therapeutic target. p97 extracts polypeptide substrates from macromolecular assemblies by hydrolysis-driven translocation through its central pore. Growing evidence indicates that this activity is highly coordinated by "adapter" partner proteins, of which more than 30 have been identified and are commonly described to facilitate translocation through substrate recruitment or modification. In so doing, these adapters enable critical p97-dependent functions such as extraction of misfolded proteins from the endoplasmic reticulum or mitochondria, and are likely the reason for the extreme functional diversity of p97 relative to other AAA+ translocases. Here, we review the known functions of adapter proteins and highlight recent structural and biochemical advances that have begun to reveal the diverse molecular bases for adapter-mediated regulation of p97 function. These studies suggest that the range of mechanisms by which p97 activity is controlled is vastly underexplored with significant advances possible for understanding p97 regulation by the most known adapters.
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Affiliation(s)
- Julian R Braxton
- Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, San Francisco, California, USA; Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, USA
| | - Daniel R Southworth
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, USA.
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10
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Tsioras K, Smith KC, Edassery SL, Garjani M, Li Y, Williams C, McKenna ED, Guo W, Wilen AP, Hark TJ, Marklund SL, Ostrow LW, Gilthorpe JD, Ichida JK, Kalb RG, Savas JN, Kiskinis E. Analysis of proteome-wide degradation dynamics in ALS SOD1 iPSC-derived patient neurons reveals disrupted VCP homeostasis. Cell Rep 2023; 42:113160. [PMID: 37776851 PMCID: PMC10785776 DOI: 10.1016/j.celrep.2023.113160] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/18/2023] [Accepted: 09/06/2023] [Indexed: 10/02/2023] Open
Abstract
Mutations in SOD1 cause amyotrophic lateral sclerosis (ALS) through gain-of-function effects, yet the mechanisms by which misfolded mutant SOD1 (mutSOD1) protein impairs human motor neurons (MNs) remain unclear. Here, we use induced-pluripotent-stem-cell-derived MNs coupled to metabolic stable isotope labeling and mass spectrometry to investigate proteome-wide degradation dynamics. We find several proteins, including the ALS-causal valosin-containing protein (VCP), which predominantly acts in proteasome degradation and autophagy, that degrade slower in mutSOD1 relative to isogenic control MNs. The interactome of VCP is altered in mutSOD1 MNs in vitro, while VCP selectively accumulates in the affected motor cortex of ALS-SOD1 patients. Overexpression of VCP rescues mutSOD1 toxicity in MNs in vitro and in a C. elegans model in vivo, in part due to its ability to modulate the degradation of insoluble mutSOD1. Our results demonstrate that VCP contributes to mutSOD1-dependent degeneration, link two distinct ALS-causal genes, and highlight selective protein degradation impairment in ALS pathophysiology.
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Affiliation(s)
- Konstantinos Tsioras
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Kevin C Smith
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Seby L Edassery
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Mehraveh Garjani
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Yichen Li
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Zilkha Neurogenetic Institute, University of Southern California, Keck School of Medicine, Los Angeles, CA 90033, USA
| | - Chloe Williams
- Department of Integrative Medical Biology, Umeå University, 90187 Umeå, Sweden
| | - Elizabeth D McKenna
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Wenxuan Guo
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Zilkha Neurogenetic Institute, University of Southern California, Keck School of Medicine, Los Angeles, CA 90033, USA
| | - Anika P Wilen
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Timothy J Hark
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Stefan L Marklund
- Department of Medical Biosciences, Clinical Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Lyle W Ostrow
- Department of Neurology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | | | - Justin K Ichida
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Zilkha Neurogenetic Institute, University of Southern California, Keck School of Medicine, Los Angeles, CA 90033, USA
| | - Robert G Kalb
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jeffrey N Savas
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Evangelos Kiskinis
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA; Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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11
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Rao B, Wang Q, Yao D, Xia Y, Li W, Xie Y, Li S, Cao M, Shen Y, Qin A, Zhao J, Cao Y. The cryo-EM structure of the human ERAD retrotranslocation complex. SCIENCE ADVANCES 2023; 9:eadi5656. [PMID: 37831771 PMCID: PMC10575581 DOI: 10.1126/sciadv.adi5656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 09/12/2023] [Indexed: 10/15/2023]
Abstract
Endoplasmic reticulum-associated degradation (ERAD) maintains protein homeostasis by retrieving misfolded proteins from the endoplasmic reticulum (ER) lumen into the cytosol for degradation. The retrotranslocation of misfolded proteins across the ER membrane is an energy-consuming process, with the detailed transportation mechanism still needing clarification. We determined the cryo-EM structures of the hetero-decameric complex formed by the Derlin-1 tetramer and the p97 hexamer. It showed an intriguing asymmetric complex and a putative coordinated squeezing movement in Derlin-1 and p97 parts. With the conformational changes of p97 induced by its ATP hydrolysis activities, the Derlin-1 channel could be torn into a "U" shape with a large opening to the lipidic environment, thereby forming an entry for the substrates in the ER membrane. The EM analysis showed that p97 formed a functional protein complex with Derlin-1, revealing the coupling mechanism between the ERAD retrotranslocation and the ATP hydrolysis activities.
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Affiliation(s)
- Bing Rao
- Department of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implant, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Qian Wang
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Deqiang Yao
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
- State Key Laboratory of Oncogenes and Related Genes, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Ying Xia
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Wenguo Li
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Yuming Xie
- College of Basic Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Shaobai Li
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Mi Cao
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Yafeng Shen
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - An Qin
- Department of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implant, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Department of Orthopaedics, Shanghai Frontiers Science Center of Degeneration and Regeneration in Skeletal System, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Jie Zhao
- Department of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implant, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Department of Orthopaedics, Shanghai Frontiers Science Center of Degeneration and Regeneration in Skeletal System, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Yu Cao
- Department of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implant, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
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12
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Jones NH, Liu Q, Urnavicius L, Dahan NE, Vostal LE, Kapoor TM. Allosteric activation of VCP, a AAA unfoldase, by small molecule mimicry. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.02.560478. [PMID: 37873168 PMCID: PMC10592943 DOI: 10.1101/2023.10.02.560478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The loss of function of AAA (ATPases associated with diverse cellular activities) mechanoenzymes has been linked to diseases, and small molecules that activate these proteins can be powerful tools to probe mechanisms and test therapeutic hypotheses. Unlike chemical inhibitors that can bind a single conformational state to block enzyme activity, activator binding must be permissive to different conformational states needed for enzyme function. However, we do not know how AAA proteins can be activated by small molecules. Here, we focus on valosin-containing protein (VCP)/p97, a AAA unfoldase whose loss of function has been linked to protein aggregation-based disorders, to identify druggable sites for chemical activators. We identified VCP Activator 1 (VA1), a compound that dose-dependently stimulates VCP ATPase activity up to ∼3-fold. Our cryo-EM studies resulted in structures (∼2.9-3.5 Å-resolution) of VCP in apo and ADP-bound states, and revealed VA1 binding an allosteric pocket near the C-terminus in both states. Engineered mutations in the VA1 binding site confer resistance to VA1, and furthermore, modulate VCP activity to a similar level as VA1-mediated activation. The VA1 binding site can alternatively be occupied by a phenylalanine residue in the VCP C-terminal tail, a motif that is post-translationally modified and interacts with cofactors. Together, our findings uncover a druggable allosteric site and a mechanism of enzyme regulation that can be tuned through small molecule mimicry. Significance The loss of function of valosin-containing protein (VCP/p97), a mechanoenzyme from the AAA superfamily that hydrolyzes ATP and uses the released energy to extract or unfold substrate proteins, is linked to protein aggregation-based disorders. However, druggable allosteric sites to activate VCP, or any AAA mechanoenzyme, have not been identified. Here, we report cryo-EM structures of VCP in two states in complex with VA1, a compound we identified that dose-dependently stimulates VCP's ATP hydrolysis activity. The VA1 binding site can also be occupied by a phenylalanine residue in the VCP C-terminal tail, suggesting that VA1 acts through mimicry of this interaction. Our study reveals a druggable allosteric site and a mechanism of enzyme regulation.
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13
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Batra S, Vaquer-Alicea J, Manon VA, Kashmer OM, Lemoff A, Cairns NJ, White CL, Diamond MI. VCP increases or decreases tau seeding using specific cofactors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.30.555637. [PMID: 37693404 PMCID: PMC10491269 DOI: 10.1101/2023.08.30.555637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Background Neurodegenerative tauopathies may progress based on seeding by pathological tau assemblies, whereby an aggregate is released from one cell, gains entry to an adjacent or connected cell, and serves as a specific template for its own replication in the cytoplasm. In vitro seeding reactions typically take days, yet seeding into the complex cytoplasmic milieu can happen within hours. A cellular machinery might regulate this process, but potential players are unknown. Methods We used proximity labeling to identify factors that control seed amplification. We fused split-APEX2 to the C-terminus of tau repeat domain (RD) to reconstitute peroxidase activity upon seeded intracellular tau aggregation. We identified valosin containing protein (VCP/p97) 5h after seeding. Mutations in VCP underlie two neurodegenerative diseases, multisystem proteinopathy and vacuolar tauopathy, but its mechanistic role is unclear. We utilized tau biosensors, a cellular model for tau aggregation, to study the effects of VCP on tau seeding. Results VCP knockdown reduced tau seeding. However, distinct chemical inhibitors of VCP and the proteasome had opposing effects on aggregation, but only when given <8h of seed exposure. ML-240 increased seeding efficiency ~40x, whereas NMS-873 decreased seeding efficiency by 50%, and MG132 increased seeding ~10x. We screened VCP co-factors in HEK293 biosensor cells by genetic knockout or knockdown. Reduction of ATXN3, NSFL1C, UBE4B, NGLY1, and OTUB1 decreased tau seeding, as did NPLOC4, which also uniquely increased soluble tau levels. Reduction of FAF2 and UBXN6 increased tau seeding. Conclusions VCP uses distinct cofactors to determine seed replication efficiency, consistent with a dedicated cytoplasmic processing complex that directs seeds towards dissolution vs. amplification.
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Affiliation(s)
- Sushobhna Batra
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Jaime Vaquer-Alicea
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Victor A Manon
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Omar M Kashmer
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Andrew Lemoff
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX
| | - Nigel J Cairns
- Department of Clinical and Biological Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - Charles L White
- Department of Pathology, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Marc I Diamond
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX
- Department of Neurology, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX
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14
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Chu S, Xie X, Payan C, Stochaj U. Valosin containing protein (VCP): initiator, modifier, and potential drug target for neurodegenerative diseases. Mol Neurodegener 2023; 18:52. [PMID: 37545006 PMCID: PMC10405438 DOI: 10.1186/s13024-023-00639-y] [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: 02/20/2023] [Accepted: 06/27/2023] [Indexed: 08/08/2023] Open
Abstract
The AAA+ ATPase valosin containing protein (VCP) is essential for cell and organ homeostasis, especially in cells of the nervous system. As part of a large network, VCP collaborates with many cofactors to ensure proteostasis under normal, stress, and disease conditions. A large number of mutations have revealed the importance of VCP for human health. In particular, VCP facilitates the dismantling of protein aggregates and the removal of dysfunctional organelles. These are critical events to prevent malfunction of the brain and other parts of the nervous system. In line with this idea, VCP mutants are linked to the onset and progression of neurodegeneration and other diseases. The intricate molecular mechanisms that connect VCP mutations to distinct brain pathologies continue to be uncovered. Emerging evidence supports the model that VCP controls cellular functions on multiple levels and in a cell type specific fashion. Accordingly, VCP mutants derail cellular homeostasis through several mechanisms that can instigate disease. Our review focuses on the association between VCP malfunction and neurodegeneration. We discuss the latest insights in the field, emphasize open questions, and speculate on the potential of VCP as a drug target for some of the most devastating forms of neurodegeneration.
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Affiliation(s)
- Siwei Chu
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada
| | - Xinyi Xie
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada
| | - Carla Payan
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada
| | - Ursula Stochaj
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada.
- Quantitative Life Sciences Program, McGill University, Montreal, Canada.
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15
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Braxton JR, Altobelli CR, Tucker MR, Tse E, Thwin AC, Arkin MR, Southworth DR. The p97/VCP adapter UBXD1 drives AAA+ remodeling and ring opening through multi-domain tethered interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.15.540864. [PMID: 37292947 PMCID: PMC10245715 DOI: 10.1101/2023.05.15.540864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
p97/VCP is an essential cytosolic AAA+ ATPase hexamer that extracts and unfolds substrate polypeptides during protein homeostasis and degradation. Distinct sets of p97 adapters guide cellular functions but their roles in direct control of the hexamer are unclear. The UBXD1 adapter localizes with p97 in critical mitochondria and lysosome clearance pathways and contains multiple p97-interacting domains. We identify UBXD1 as a potent p97 ATPase inhibitor and report structures of intact p97:UBXD1 complexes that reveal extensive UBXD1 contacts across p97 and an asymmetric remodeling of the hexamer. Conserved VIM, UBX, and PUB domains tether adjacent protomers while a connecting strand forms an N-terminal domain lariat with a helix wedged at the interprotomer interface. An additional VIM-connecting helix binds along the second AAA+ domain. Together these contacts split the hexamer into a ring-open conformation. Structures, mutagenesis, and comparisons to other adapters further reveal how adapters containing conserved p97-remodeling motifs regulate p97 ATPase activity and structure.
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Affiliation(s)
- Julian R. Braxton
- Graduate Program in Chemistry and Chemical Biology; University of California, San Francisco; San Francisco, CA 94158, USA
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Chad R. Altobelli
- Graduate Program in Chemistry and Chemical Biology; University of California, San Francisco; San Francisco, CA 94158, USA
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Maxwell R. Tucker
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
- Graduate Program in Biophysics; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Eric Tse
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Aye C. Thwin
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Michelle R. Arkin
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Daniel R. Southworth
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
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16
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Valimehr S, Sethi A, Shukla M, Bhattacharyya S, Kazemi M, Rouiller I. Molecular Mechanisms Driving and Regulating the AAA+ ATPase VCP/p97, an Important Therapeutic Target for Treating Cancer, Neurological and Infectious Diseases. Biomolecules 2023; 13:biom13050737. [PMID: 37238606 DOI: 10.3390/biom13050737] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/15/2023] [Accepted: 04/13/2023] [Indexed: 05/28/2023] Open
Abstract
p97/VCP, a highly conserved type II ATPase associated with diverse cellular activities (AAA+ ATPase), is an important therapeutic target in the treatment of neurodegenerative diseases and cancer. p97 performs a variety of functions in the cell and facilitates virus replication. It is a mechanochemical enzyme that generates mechanical force from ATP-binding and hydrolysis to perform several functions, including unfolding of protein substrates. Several dozens of cofactors/adaptors interact with p97 and define the multifunctionality of p97. This review presents the current understanding of the molecular mechanism of p97 during the ATPase cycle and its regulation by cofactors and small-molecule inhibitors. We compare detailed structural information obtained in different nucleotide states in the presence and absence of substrates and inhibitors. We also review how pathogenic gain-of-function mutations modify the conformational changes of p97 during the ATPase cycle. Overall, the review highlights how the mechanistic knowledge of p97 helps in designing pathway-specific modulators and inhibitors.
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Affiliation(s)
- Sepideh Valimehr
- Department of Biochemistry & Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
- Bio21 Ian Holmes Imaging Centre, Department of Biochemistry & Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Ashish Sethi
- Department of Biochemistry & Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
- Australian Nuclear Science Technology Organisation, The Australian Synchrotron, 800 Blackburn Rd, Clayton, VIC 3168, Australia
| | - Manjari Shukla
- Department of Bioscience and Bioengineering, Indian Institute of Technology Jodhpur, Jodhpur 342030, Rajasthan, India
| | - Sudipta Bhattacharyya
- Department of Bioscience and Bioengineering, Indian Institute of Technology Jodhpur, Jodhpur 342030, Rajasthan, India
| | - Mohsen Kazemi
- Department of Biochemistry & Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Isabelle Rouiller
- Department of Biochemistry & Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, The University of Melbourne, Melbourne, VIC 3010, Australia
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Phan JM, Creekmore BC, Nguyen AT, Bershadskaya DD, Darwich NF, Lee EB. Novel VCP activator reverses multisystem proteinopathy nuclear proteostasis defects and enhances TDP-43 aggregate clearance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.15.532082. [PMID: 36993559 PMCID: PMC10055171 DOI: 10.1101/2023.03.15.532082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Pathogenic variants in VCP cause multisystem proteinopathy (MSP), a disease characterized by multiple clinical phenotypes including inclusion body myopathy, Paget's disease of the bone, and frontotemporal dementia (FTD). How such diverse phenotypes are driven by pathogenic VCP variants is not known. We found that these diseases exhibit a common pathologic feature, ubiquitinated intranuclear inclusions affecting myocytes, osteoclasts and neurons. Moreover, knock-in cell lines harboring MSP variants show a reduction in nuclear VCP. Given that MSP is associated with neuronal intranuclear inclusions comprised of TDP-43 protein, we developed a cellular model whereby proteostatic stress results in the formation of insoluble intranuclear TDP-43 aggregates. Consistent with a loss of nuclear VCP function, cells harboring MSP variants or cells treated with VCP inhibitor exhibited decreased clearance of insoluble intranuclear TDP-43 aggregates. Moreover, we identified four novel compounds that activate VCP primarily by increasing D2 ATPase activity whereby pharmacologic VCP activation appears to enhance clearance of insoluble intranuclear TDP-43 aggregate. Our findings suggest that VCP function is important for nuclear protein homeostasis, that MSP may be the result of impaired nuclear proteostasis, and that VCP activation may be potential therapeutic by virtue of enhancing the clearance of intranuclear protein aggregates.
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Affiliation(s)
- Jessica M Phan
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Benjamin C Creekmore
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Aivi T Nguyen
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Darya D Bershadskaya
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Nabil F Darwich
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Edward B Lee
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
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18
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Williams C, Dong KC, Arkinson C, Martin A. The Ufd1 cofactor determines the linkage specificity of polyubiquitin chain engagement by the AAA+ ATPase Cdc48. Mol Cell 2023; 83:759-769.e7. [PMID: 36736315 PMCID: PMC9992269 DOI: 10.1016/j.molcel.2023.01.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 12/13/2022] [Accepted: 01/11/2023] [Indexed: 02/05/2023]
Abstract
The AAA+ ATPase Cdc48 utilizes the cofactor Ufd1/Npl4 to bind and thread polyubiquitinated substrates for their extraction from complexes or membranes and often for subsequent proteasomal degradation. Previous studies indicated that Cdc48 engages polyubiquitin chains through the Npl4-mediated unfolding of an initiator ubiquitin; yet, the underlying principles remain largely unknown. Using FRET-based assays, we revealed the mechanisms and kinetics of ubiquitin unfolding, insertion into the ATPase, and unfolding of the ubiquitin-attached substrate. We found that Cdc48 uses Ufd1's UT3 domain to bind a K48-linked ubiquitin on the initiator's proximal side of the chain, thereby directing the initiator toward rapid unfolding by Npl4 and engagement by Cdc48. Ubiquitins on the initiator's distal side increase substrate affinity and facilitate unfolding but impede substrate release from Cdc48-Ufd1/Npl4 in the absence of additional cofactors. Our findings explain how Cdc48-UN efficiently processes substrates with K48-linked chains of 4-6 ubiquitins, which represent most cellular polyubiquitinated proteins.
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Affiliation(s)
- Cameron Williams
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Ken C Dong
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Connor Arkinson
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Andreas Martin
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA.
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19
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Saha I, Yuste-Checa P, Da Silva Padilha M, Guo Q, Körner R, Holthusen H, Trinkaus VA, Dudanova I, Fernández-Busnadiego R, Baumeister W, Sanders DW, Gautam S, Diamond MI, Hartl FU, Hipp MS. The AAA+ chaperone VCP disaggregates Tau fibrils and generates aggregate seeds in a cellular system. Nat Commun 2023; 14:560. [PMID: 36732333 PMCID: PMC9894937 DOI: 10.1038/s41467-023-36058-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 01/13/2023] [Indexed: 02/04/2023] Open
Abstract
Amyloid-like aggregates of the microtubule-associated protein Tau are associated with several neurodegenerative disorders including Alzheimer's disease. The existence of cellular machinery for the removal of such aggregates has remained unclear, as specialized disaggregase chaperones are thought to be absent in mammalian cells. Here we show in cell culture and in neurons that the hexameric ATPase valosin-containing protein (VCP) is recruited to ubiquitylated Tau fibrils, resulting in their efficient disaggregation. Aggregate clearance depends on the functional cooperation of VCP with heat shock 70 kDa protein (Hsp70) and the ubiquitin-proteasome machinery. While inhibition of VCP activity stabilizes large Tau aggregates, disaggregation by VCP generates seeding-active Tau species as byproduct. These findings identify VCP as a core component of the machinery for the removal of neurodegenerative disease aggregates and suggest that its activity can be associated with enhanced aggregate spreading in tauopathies.
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Affiliation(s)
- Itika Saha
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
| | - Patricia Yuste-Checa
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
| | - Miguel Da Silva Padilha
- Molecular Neurodegeneration Group, Max Planck Institute for Biological Intelligence, 82152, Martinsried, Germany.,Department of Molecules - Signaling - Development, Max Planck Institute for Biological Intelligence, Am Klopferspitz 18, 82152, Martinsried, Germany.,Center for Anatomy, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50931, Cologne, Germany
| | - Qiang Guo
- Department of Structural Molecular Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Roman Körner
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Hauke Holthusen
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Victoria A Trinkaus
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Department of Structural Molecular Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Irina Dudanova
- Molecular Neurodegeneration Group, Max Planck Institute for Biological Intelligence, 82152, Martinsried, Germany.,Department of Molecules - Signaling - Development, Max Planck Institute for Biological Intelligence, Am Klopferspitz 18, 82152, Martinsried, Germany.,Center for Anatomy, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50931, Cologne, Germany
| | - Rubén Fernández-Busnadiego
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA.,Department of Structural Molecular Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Institute of Neuropathology, University Medical Center Göttingen, 37099, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Wolfgang Baumeister
- Department of Structural Molecular Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - David W Sanders
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, 75390, TX, USA.,Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Saurabh Gautam
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Boehringer Ingelheim International GmbH, 55216, Ingelheim, Germany.,ViraTherapeutics GmbH, 6063, Rum, Austria
| | - Marc I Diamond
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, 75390, TX, USA
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany. .,Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA. .,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
| | - Mark S Hipp
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany. .,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany. .,School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany. .,Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan, 1, 9713 AV, Groningen, The Netherlands.
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20
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Ahlstedt BA, Ganji R, Raman M. The functional importance of VCP to maintaining cellular protein homeostasis. Biochem Soc Trans 2022; 50:1457-1469. [PMID: 36196920 PMCID: PMC9704522 DOI: 10.1042/bst20220648] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/09/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022]
Abstract
The AAA-ATPase (ATPases associated with diverse cellular activities) valosin-containing protein (VCP), is essential for many cellular pathways including but not limited to endoplasmic reticulum-associated degradation (ERAD), DNA damage responses, and cell cycle regulation. VCP primarily identifies ubiquitylated proteins in these pathways and mediates their unfolding and degradation by the 26S proteasome. This review summarizes recent research on VCP that has uncovered surprising new ways that this ATPase is regulated, new aspects of recognition of substrates and novel pathways and substrates that utilize its activity.
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Affiliation(s)
- Brittany A. Ahlstedt
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, U.S.A
| | - Rakesh Ganji
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, U.S.A
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, U.S.A
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21
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Schiava M, Ikenaga C, Villar-Quiles RN, Caballero-Ávila M, Topf A, Nishino I, Kimonis V, Udd B, Schoser B, Zanoteli E, Souza PVS, Tasca G, Lloyd T, Lopez-de Munain A, Paradas C, Pegoraro E, Nadaj-Pakleza A, De Bleecker J, Badrising U, Alonso-Jiménez A, Kostera-Pruszczyk A, Miralles F, Shin JH, Bevilacqua JA, Olivé M, Vorgerd M, Kley R, Brady S, Williams T, Domínguez-González C, Papadimas GK, Warman-Chardon J, Claeys KG, de Visser M, Muelas N, LaForet P, Malfatti E, Alfano LN, Nair SS, Manousakis G, Kushlaf HA, Harms MB, Nance C, Ramos-Fransi A, Rodolico C, Hewamadduma C, Cetin H, García-García J, Pál E, Farrugia ME, Lamont PJ, Quinn C, Nedkova-Hristova V, Peric S, Luo S, Oldfors A, Taylor K, Ralston S, Stojkovic T, Weihl C, Diaz-Manera J. Genotype-phenotype correlations in valosin-containing protein disease: a retrospective muticentre study. J Neurol Neurosurg Psychiatry 2022; 93:jnnp-2022-328921. [PMID: 35896379 PMCID: PMC9880250 DOI: 10.1136/jnnp-2022-328921] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 06/28/2022] [Indexed: 01/31/2023]
Abstract
BACKGROUND Valosin-containing protein (VCP) disease, caused by mutations in the VCP gene, results in myopathy, Paget's disease of bone (PBD) and frontotemporal dementia (FTD). Natural history and genotype-phenotype correlation data are limited. This study characterises patients with mutations in VCP gene and investigates genotype-phenotype correlations. METHODS Descriptive retrospective international study collecting clinical and genetic data of patients with mutations in the VCP gene. RESULTS Two hundred and fifty-five patients (70.0% males) were included in the study. Mean age was 56.8±9.6 years and mean age of onset 45.6±9.3 years. Mean diagnostic delay was 7.7±6 years. Symmetric lower limb weakness was reported in 50% at onset progressing to generalised muscle weakness. Other common symptoms were ventilatory insufficiency 40.3%, PDB 28.2%, dysautonomia 21.4% and FTD 14.3%. Fifty-seven genetic variants were identified, 18 of these no previously reported. c.464G>A (p.Arg155His) was the most frequent variant, identified in the 28%. Full time wheelchair users accounted for 19.1% with a median time from disease onset to been wheelchair user of 8.5 years. Variant c.463C>T (p.Arg155Cys) showed an earlier onset (37.8±7.6 year) and a higher frequency of axial and upper limb weakness, scapular winging and cognitive impairment. Forced vital capacity (FVC) below 50% was as risk factor for being full-time wheelchair user, while FVC <70% and being a full-time wheelchair user were associated with death. CONCLUSION This study expands the knowledge on the phenotypic presentation, natural history, genotype-phenotype correlations and risk factors for disease progression of VCP disease and is useful to improve the care provided to patient with this complex disease.
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Affiliation(s)
- Marianela Schiava
- John Walton Muscular Dystrophy Research Centre, Newcastle University, and Newcastle Hospitals NHS Foundation Trusts, Newcastle Upon Tyne, UK
| | - Chiseko Ikenaga
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rocío Nur Villar-Quiles
- APHP, Centre de référence des maladies neuromusculaires, Institut de Myologie, Sorbonne Université, APHP, Hôpital Pitié-Salpêtrière, Paris, France
| | - Marta Caballero-Ávila
- Neuromuscular Disorders Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Ana Topf
- Newcastle University and Newcastle Hospitals NHS Foundation Trusts, Newcastle University, Newcastle upon Tyne, UK
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
| | - Virginia Kimonis
- Department of Pediatrics Division of Genetics and Genomic Medicine, University of California-Irvine Medical Center Children’s Hospital of Orange County, Orange, California, USA
| | - Bjarne Udd
- Tampere Neuromuscular Center, Tampere University Hospital, Tampere, Finland
- Folkhalsan Genetic Institute, Helsinki University, Helsinki, Finland
| | - Benedikt Schoser
- Department of Neurology, Friedrich-Baur-Institute Ludwig Maximilian University Clinics, Munich, Germany
| | - Edmar Zanoteli
- Department of Neurology, School of Medicine, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | | | - Giorgio Tasca
- Unità Operativa Complessa di Neurologia, Fondazione Policlinico Universitario A Gemelli, IRCCS, Rome, Italy
| | - Thomas Lloyd
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Adolfo Lopez-de Munain
- Biodonostia Neurosciences Area Group of Neuromuscular Diseases Biodonostia-Osakidetza Basque Health Service, San Sebastian, Spain
| | - Carmen Paradas
- Neurology Department, Neuromuscular Disorders Unit, Hospital Universitario Virgen del Rocío, Sevilla, Spain
- Instituto de Biomedicina de Sevilla, Sevilla, Spain
- Center for Biomedical Network Research on Neurodegenerative Disorders (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Elena Pegoraro
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Aleksandra Nadaj-Pakleza
- Department of Neurology, Centre de Reference des Maldies Neuromusculaires Nord-Est-Ile de France, University Hospital of Strasbourg, Strasbourg, France
| | - Jan De Bleecker
- Department of Neurology and Neuromuscular Reference Center, Ghent University Hospital, Ghent, Belgium
| | - Umesh Badrising
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Alicia Alonso-Jiménez
- Department of Neurology, Neuromuscular Reference Centre, Antwerp University Hospital, Universiteit Antwerpen, Instituut Born Bunge, Antwerpen, Belgium
| | - Anna Kostera-Pruszczyk
- Department of Neurology, Medical University of Warsaw, European Reference Network ERN-NMD, Warsaw, Poland
| | - Francesc Miralles
- Department of Neurology, Unitat de Patologia Neuromuscular i Gabinet d’electrodiagnòstic, Hospital Universitari Son Espases, Palma de Mallorca, Spain
| | - Jin-Hong Shin
- Laboratory of Molecular Neurology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
| | - Jorge Alfredo Bevilacqua
- Unidad Neuromuscular, Departamento de Neurología y Neurocirugía, Hospital Clínico Universidad de Chile, Santiago de Chile, Chile
- Departamento de Neurología y Neurocirugía Clínica, Clínica Dávila, Santiago Chile, Chile
| | - Montse Olivé
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- Deaprtment of Neurology, Neuromuscular Disorders Unit, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain
| | - Matthias Vorgerd
- Heimer Institut for Muscle Research, Klinikum Bergmannsheil, Ruhr University, Bochum, Germany
| | - Rudi Kley
- Department of Neurology and Clinical Neurophysiology, St Marien-Hospital Borken, Borken, Germany
| | - Stefen Brady
- Neurology Department, John Radcliffe Hospital, Oxford, UK
| | - Timothy Williams
- Newcastle Motor Neurone Disease Care Centre, Royal Victoria Infirmary, Newcastle, UK
| | - Cristina Domínguez-González
- Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Madrid, Spain
- Neurology Service, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - George K Papadimas
- First Department of Neurology, Medical School, Eginition Hospital and National and Kapodistrian University of Athens, Athens, Greece
| | - Jodi Warman-Chardon
- Department of Medicine, Ottawa Neuromuscular Centre, Ottawa Hospital, Ottawa, Ontario, Canada
| | - Kristl G Claeys
- Department of Neurology, University Hospitals Leuven, Leuven, Belgium
- KU Leuven Laboratory for Muscle Diseases and Neuropathies, Leuven, Belgium
| | - Marianne de Visser
- Department of Neurology, Academic Medical Center, Amsterdam, The Netherlands
| | - Nuria Muelas
- Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Madrid, Spain
- Neuromuscular Unit, Department of Neurology, Hospital Universitari i Politècnic La Fe, Valencia, Spain
- Neuromuscular and Ataxias Research Group, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
| | - Pascal LaForet
- Neurology department, Raymond-Poincaré hospital, APHP, UVSQ, Paris-Saclay University, Paris, France
| | - Edoardo Malfatti
- APHP, Neuromuscular Reference Center Nord-Est-Ile-de-France, Henri Mondor Hospital, Université Paris Est, U955, INSERM, Créteil, IMRB, Paris, France
| | - Lindsay N Alfano
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Sruthi S Nair
- Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
| | - Georgios Manousakis
- Department of Neurology, University of Minnesota Hospital, Minneapolis, Minnesota, USA
| | - Hani A Kushlaf
- Department of Neurology & Rehabilitation Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Matthew B Harms
- NewYork Presbyterian Columbia University Irving Medical Centre, New York, New York, USA
| | - Christopher Nance
- Department of Neurology, Carver College of Medicine at the University of Iowa, Iowa, Iowa, USA
| | - Alba Ramos-Fransi
- Neuromuscular Unit, Neurology Department, Hospital Germas Trias i Pujol, Badalona, Spain
| | - Carmelo Rodolico
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Channa Hewamadduma
- Sheffield Institute for translational neurosciences (SITRAN), Neuroscience Institute, University of Sheffield, Sheffield, UK
| | - Hakan Cetin
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Jorge García-García
- Neurology Department, Complejo Hospitalario Universitario de Albacete, Albacete, Spain
| | - Endre Pál
- Department of Neurology, University of Pécs, Pécs, Hungary
| | - Maria Elena Farrugia
- Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow, UK
| | - Phillipa J Lamont
- Department of Neurology, Royal Perth Hospital, Perth, Western Australia, Australia
| | - Colin Quinn
- Neuromuscular Division, Neurology Department, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Stojan Peric
- Neurology Clinic, Clinical Centre of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Sushan Luo
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
- National Center for Neurological Disorders, Shanghai, China
| | - Anders Oldfors
- Department of Laboratory Medicine, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | | | - Stuart Ralston
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Tanya Stojkovic
- APHP, Centre de référence des maladies neuromusculaires, Institut de Myologie, Sorbonne Université, APHP, Hôpital Pitié-Salpêtrière, Paris, France
| | - Conrad Weihl
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jordi Diaz-Manera
- John Walton Muscular Dystrophy Research Centre, Newcastle University, and Newcastle Hospitals NHS Foundation Trusts, Newcastle Upon Tyne, UK
- Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
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Compounds activating VCP D1 ATPase enhance both autophagic and proteasomal neurotoxic protein clearance. Nat Commun 2022; 13:4146. [PMID: 35842429 PMCID: PMC9288506 DOI: 10.1038/s41467-022-31905-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 07/08/2022] [Indexed: 01/04/2023] Open
Abstract
Enhancing the removal of aggregate-prone toxic proteins is a rational therapeutic strategy for a number of neurodegenerative diseases, especially Huntington's disease and various spinocerebellar ataxias. Ideally, such approaches should preferentially clear the mutant/misfolded species, while having minimal impact on the stability of wild-type/normally-folded proteins. Furthermore, activation of both ubiquitin-proteasome and autophagy-lysosome routes may be advantageous, as this would allow effective clearance of both monomeric and oligomeric species, the latter which are inaccessible to the proteasome. Here we find that compounds that activate the D1 ATPase activity of VCP/p97 fulfill these requirements. Such effects are seen with small molecule VCP activators like SMER28, which activate autophagosome biogenesis by enhancing interactions of PI3K complex components to increase PI(3)P production, and also accelerate VCP-dependent proteasomal clearance of such substrates. Thus, this mode of VCP activation may be a very attractive target for many neurodegenerative diseases.
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23
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Assembly and function of branched ubiquitin chains. Trends Biochem Sci 2022; 47:759-771. [DOI: 10.1016/j.tibs.2022.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 03/23/2022] [Accepted: 04/05/2022] [Indexed: 12/11/2022]
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Abstract
BACKGROUND Neuronal uptake and subsequent spread of proteopathic seeds, such as αS (alpha-synuclein), Tau, and TDP-43, contribute to neurodegeneration. The cellular machinery participating in this process is poorly understood. One proteinopathy called multisystem proteinopathy (MSP) is associated with dominant mutations in Valosin Containing Protein (VCP). MSP patients have muscle and neuronal degeneration characterized by aggregate pathology that can include αS, Tau and TDP-43. METHODS We performed a fluorescent cell sorting based genome-wide CRISPR-Cas9 screen in αS biosensors. αS and TDP-43 seeding activity under varied conditions was assessed using FRET/Flow biosensor cells or immunofluorescence for phosphorylated αS or TDP-43 in primary cultured neurons. We analyzed in vivo seeding activity by immunostaining for phosphorylated αS following intrastriatal injection of αS seeds in control or VCP disease mutation carrying mice. RESULTS One hundred fifty-four genes were identified as suppressors of αS seeding. One suppressor, VCP when chemically or genetically inhibited increased αS seeding in cells and neurons. This was not due to an increase in αS uptake or αS protein levels. MSP-VCP mutation expression increased αS seeding in cells and neurons. Intrastriatal injection of αS preformed fibrils (PFF) into VCP-MSP mutation carrying mice increased phospho αS expression as compared to control mice. Cells stably expressing fluorescently tagged TDP-43 C-terminal fragment FRET pairs (TDP-43 biosensors) generate FRET when seeded with TDP-43 PFF but not monomeric TDP-43. VCP inhibition or MSP-VCP mutant expression increases TDP-43 seeding in TDP-43 biosensors. Similarly, treatment of neurons with TDP-43 PFFs generates high molecular weight insoluble phosphorylated TDP-43 after 5 days. This TDP-43 seed dependent increase in phosphorlyated TDP-43 is further augmented in MSP-VCP mutant expressing neurons. CONCLUSION Using an unbiased screen, we identified the multifunctional AAA ATPase VCP as a suppressor of αS and TDP-43 aggregate seeding in cells and neurons. VCP facilitates the clearance of damaged lysosomes via lysophagy. We propose that VCP's surveillance of permeabilized endosomes may protect against the proteopathic spread of pathogenic protein aggregates. The spread of distinct aggregate species may dictate the pleiotropic phenotypes and pathologies in VCP associated MSP.
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Kobakhidze G, Sethi A, Valimehr S, Ralph SA, Rouiller I. The AAA+ ATPase p97 as a novel parasite and tuberculosis drug target. Trends Parasitol 2022; 38:572-590. [DOI: 10.1016/j.pt.2022.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
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Johnson MA, Klickstein JA, Khanna R, Gou Y, Raman M. The Cure VCP Scientific Conference 2021: Molecular and clinical insights into neurodegeneration and myopathy linked to multisystem proteinopathy-1 (MSP-1). Neurobiol Dis 2022; 169:105722. [PMID: 35405261 PMCID: PMC9169230 DOI: 10.1016/j.nbd.2022.105722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/08/2022] [Accepted: 04/05/2022] [Indexed: 12/17/2022] Open
Abstract
The 2021 VCP Scientific Conference took place virtually from September 9–10, 2021. This conference, planned and organized by the nonprofit patient advocacy group Cure VCP Disease, Inc. (https://www.curevcp.org), was the first VCP focused meeting since the 215th ENMC International Workshop VCP-related multi-system proteinopathy in 2016 (Evangelista et al., 2016). Mutations in VCP cause a complex and heterogenous disease termed inclusion body myopathy (IBM) with Paget’s disease of the bone (PDB) and frontotemporal dementia (FTD) (IBMPFD), or multisystem proteinopathy 1 (MSP-1) Kimonis (n.d.), Kovach et al. (2001), Kimonis et al. (2000). In addition, VCP mutations also cause other age-related neurodegenerative disorders including amyptrophic lateral sclerosis (ALS), Parkinsonism, Charcot-Marie type II-B, vacuolar tauopathy among others (Korb et al., 2022). The objectives of this conference were as follows: (1) to provide a forum that facilitates sharing of published and unpublished information on physiological roles of p97/VCP, and on how mutations of VCP lead to diseases; (2) to bolster understanding of mechanisms involved in p97/VCP-relevant diseases and to enable identification of therapeutics to treat these conditions; (3) to identify gaps and barriers of further discoveries and translational research in the p97/VCP field; (4) to set a concrete basic and translational research agenda for future studies including crucial discussions on biomarker discoveries and patient longitudinal studies to facilitate near-term clinical trials; (5) to accelerate cross-disciplinary research collaborations among p97/VCP researchers; (6) to enable attendees to learn about new tools and reagents with the potential to facilitate p97/VCP research; (7) to assist trainees in propelling their research and to foster mentorship from leaders in the field; and (8) to promote diversity and inclusion of under-represented minorities in p97/VCP research as diversity is critically important for strong scientific research. Given the range of topics, the VCP Scientific Conference brought together over one hundred and forty individuals representing a diverse group of research scientists, trainees, medical practitioners, industry representatives, and patient advocates. Twenty-five institutions with individuals from thirteen countries attended this virtual meeting. In this report, we summarize the major topics presented at this conference by a range of experts.
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Affiliation(s)
- Michelle A Johnson
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, United States of America
| | - Jacob A Klickstein
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, United States of America
| | - Richa Khanna
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, United States of America
| | - Yunzi Gou
- Department of Pathology and Laboratory Medicine, University of California, Irvine, CA, United States of America
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, United States of America.
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27
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Das P, Xu WK, Gautam AKS, Lozano MM, Dudley JP. A Retrotranslocation Assay That Predicts Defective VCP/p97-Mediated Trafficking of a Retroviral Signal Peptide. mBio 2022; 13:e0295321. [PMID: 35089078 PMCID: PMC8725593 DOI: 10.1128/mbio.02953-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 11/18/2021] [Indexed: 12/12/2022] Open
Abstract
Studies of viral replication have provided critical insights into host processes, including protein trafficking and turnover. Mouse mammary tumor virus (MMTV) is a betaretrovirus that encodes a functional 98-amino-acid signal peptide (SP). MMTV SP is generated from both Rem and envelope precursor proteins by signal peptidase cleavage in the endoplasmic reticulum (ER) membrane. We previously showed that SP functions as a human immunodeficiency virus type 1 (HIV-1) Rev-like protein that is dependent on the AAA ATPase valosin-containing protein (VCP)/p97 to subvert ER-associated degradation (ERAD). SP contains a nuclear localization sequence (NLS)/nucleolar localization sequence (NoLS) within the N-terminal 45 amino acids. To directly determine the SP regions needed for membrane extraction and trafficking, we developed a quantitative retrotranslocation assay with biotin acceptor peptide (BAP)-tagged SP proteins. Use of alanine substitution mutants of BAP-tagged MMTV SP in retrotranslocation assays revealed that mutation of amino acids 57 and 58 (M57-58) interfered with ER membrane extraction, whereas adjacent mutations did not. The M57-58 mutant also showed reduced interaction with VCP/p97 in coimmunoprecipitation experiments. Using transfection and reporter assays to measure activity of BAP-tagged proteins, both M57-58 and an adjacent mutant (M59-61) were functionally defective compared to wild-type SP. Confocal microscopy revealed defects in SP nuclear trafficking and abnormal localization of both M57-58 and M59-61. Furthermore, purified glutathione S-transferase (GST)-tagged M57-58 and M59-61 demonstrated reduced ability to oligomerize compared to tagged wild-type SP. These experiments suggest that SP amino acids 57 and 58 are critical for VCP/p97 interaction and retrotranslocation, whereas residues 57 to 61 are critical for oligomerization and nuclear trafficking independent of the NLS/NoLS. Our results emphasize the complex host interactions with long signal peptides. IMPORTANCE Endoplasmic reticulum-associated degradation (ERAD) is a form of cellular protein quality control that is manipulated by viruses, including the betaretrovirus, mouse mammary tumor virus (MMTV). MMTV-encoded signal peptide (SP) has been shown to interact with an essential ERAD factor, VCP/p97 ATPase, to mediate its extraction from the ER membrane, also known as retrotranslocation, for RNA binding and nuclear function. In this paper, we developed a quantitative retrotranslocation assay that identified an SP substitution mutant, which is defective for VCP interaction as well as nuclear trafficking, oligomer formation, and function. An adjacent SP mutant was competent for retrotranslocation and VCP interaction but shared the other defects. Our results revealed the requirement for VCP during SP trafficking and the complex cellular pathways used by long signal peptides.
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Affiliation(s)
- Poulami Das
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Wendy Kaichun Xu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Amit Kumar Singh Gautam
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Mary M. Lozano
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Jaquelin P. Dudley
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
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Cheng C, Weiss L, Leinonen H, Shmara A, Yin HZ, Ton T, Do A, Lee J, Ta L, Mohanty E, Vargas J, Weiss J, Palczewski K, Kimonis V. VCP/p97 inhibitor CB-5083 modulates muscle pathology in a mouse model of VCP inclusion body myopathy. J Transl Med 2022; 20:21. [PMID: 34998409 PMCID: PMC8742393 DOI: 10.1186/s12967-021-03186-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 12/07/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Pathogenic gain of function variants in Valosin-containing protein (VCP) cause a unique disease characterized by inclusion body myopathy with early-onset Paget disease of bone and frontotemporal dementia (also known as Multisystem proteinopathy (MSP)). Previous studies in drosophila models of VCP disease indicate treatment with VCP inhibitors mitigates disease pathology. Earlier-generation VCP inhibitors display off-target effects and relatively low therapeutic potency. New generation of VCP inhibitors needs to be evaluated in a mouse model of VCP disease. In this study, we tested the safety and efficacy of a novel and potent VCP inhibitor, CB-5083 using VCP patient-derived myoblast cells and an animal model of VCP disease. METHODS First, we analyzed the effect of CB-5083 in patient-derived myoblasts on the typical disease autophagy and TDP-43 profile by Western blot. Next, we determined the maximum tolerated dosage of CB-5083 in mice and treated the 2-month-old VCPR155H/R155H mice for 5 months with 15 mg/kg CB-5083. We analyzed motor function monthly by Rotarod; and we assessed the end-point blood toxicology, and the muscle and brain pathology, including autophagy and TDP-43 profile, using Western blot and immunohistochemistry. We also treated 12-month-old VCPR155H/+ mice for 6 months and performed similar analysis. Finally, we assessed the potential side effects of CB-5083 on retinal function, using electroretinography in chronically treated VCPR155H/155H mice. RESULTS In vitro analyses using patient-derived myoblasts confirmed that CB-5083 can modulate expression of the proteins in the autophagy pathways. We found that chronic CB-5083 treatment is well tolerated in the homozygous mice harboring patient-specific VCP variant, R155H, and can ameliorate the muscle pathology characteristic of the disease. VCP-associated pathology biomarkers, such as elevated TDP-43 and p62 levels, were significantly reduced. Finally, to address the potential adverse effect of CB-5083 on visual function observed in a previous oncology clinical trial, we analyzed retinal function in mice treated with moderate doses of CB-5083 for 5 months and documented the absence of permanent ocular toxicity. CONCLUSIONS Altogether, these findings suggest that long-term use of CB-5083 by moderate doses is safe and can improve VCP disease-associated muscle pathology. Our results provide translationally relevant evidence that VCP inhibitors could be beneficial in the treatment of VCP disease.
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Affiliation(s)
- Cheng Cheng
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Lan Weiss
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Henri Leinonen
- Gavin Herbert Eye Institute, and the Department of Ophthalmology, Center for Translational Vision Research, University of California, Irvine, Irvine, CA, USA
| | - Alyaa Shmara
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Hong Z Yin
- Department of Neurology, University of California, Irvine, Irvine, CA, USA
| | - Timothy Ton
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Annie Do
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Jonathan Lee
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Lac Ta
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Eshanee Mohanty
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA
| | - Jesse Vargas
- Cleave Therapeutics, Inc., San Francisco, CA, USA
| | - John Weiss
- Department of Neurology, University of California, Irvine, Irvine, CA, USA
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, and the Department of Ophthalmology, Center for Translational Vision Research, University of California, Irvine, Irvine, CA, USA
- Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA, USA
- Department of Chemistry, Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, USA
| | - Virginia Kimonis
- Division of Genetics and Genomic Medicine, Dept. of Pediatrics, UC Irvine, Irvine, CA, USA.
- Department of Neurology, University of California, Irvine, Irvine, CA, USA.
- Department of Pathology, University of California, Irvine, Irvine, CA, USA.
- Department of Environmental Medicine, University of California, Irvine, Irvine, CA, USA.
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Sun X, Zhou N, Ma B, Wu W, Stoll S, Lai L, Qin G, Qiu H. Functional Inhibition of Valosin-Containing Protein Induces Cardiac Dilation and Dysfunction in a New Dominant-Negative Transgenic Mouse Model. Cells 2021; 10:2891. [PMID: 34831118 PMCID: PMC8616236 DOI: 10.3390/cells10112891] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 12/20/2022] Open
Abstract
Valosin-containing protein (VCP) was found to play a vital protective role against cardiac stresses. Genetic mutations of VCP are associated with human dilated cardiomyopathy. However, the essential role of VCP in the heart during the physiological condition remains unknown since the VCP knockout in mice is embryonically lethal. We generated a cardiac-specific dominant-negative VCP transgenic (DN-VCP TG) mouse to determine the effects of impaired VCP activity on the heart. Using echocardiography, we showed that cardiac-specific overexpression of DN-VCP induced a remarkable cardiac dilation and progressively declined cardiac function during the aging transition. Mechanistically, DN-VCP did not affect the endogenous VCP (EN-VCP) expression but significantly reduced cardiac ATPase activity in the DN-VCP TG mouse hearts, indicating a functional inhibition. DN-VCP significantly impaired the aging-related cytoplasmic/nuclear shuffling of EN-VCP and its co-factors in the heart tissues and interrupted the balance of the VCP-cofactors interaction between the activating co-factors, ubiquitin fusion degradation protein 1 (UFD-1)/nuclear protein localization protein 4 (NPL-4) complex, and its inhibiting co-factor P47, leading to the binding preference with the inhibitory co-factor, resulting in functional repression of VCP. This DN-VCP TG mouse provides a unique functional-inactivation model for investigating VCP in the heart in physiological and pathological conditions.
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Affiliation(s)
- Xiaonan Sun
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (B.M.); (W.W.); (L.L.)
| | - Ning Zhou
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92318, USA; (N.Z.); (S.S.)
| | - Ben Ma
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (B.M.); (W.W.); (L.L.)
| | - Wenqian Wu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (B.M.); (W.W.); (L.L.)
| | - Shaunrick Stoll
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92318, USA; (N.Z.); (S.S.)
| | - Lo Lai
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (B.M.); (W.W.); (L.L.)
| | - Gangjian Qin
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (B.M.); (W.W.); (L.L.)
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92318, USA; (N.Z.); (S.S.)
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30
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Conserved L464 in p97 D1-D2 linker is critical for p97 cofactor regulated ATPase activity. Biochem J 2021; 478:3185-3204. [PMID: 34405853 DOI: 10.1042/bcj20210288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 08/10/2021] [Accepted: 08/18/2021] [Indexed: 11/17/2022]
Abstract
p97 protein is a highly conserved, abundant, functionally diverse, structurally dynamic homohexameric AAA enzyme-containing N, D1, and D2 domains. A truncated p97 protein containing the N and D1 domains and the D1-D2 linker (ND1L) exhibits 79% of wild-type (WT) ATPase activity whereas the ND1 domain alone without the linker only has 2% of WT activity. To investigate the relationship between the D1-D2 linker and the D1 domain, we produced p97 ND1L mutants and demonstrated that this 22-residue linker region is essential for D1 ATPase activity. The conserved amino acid leucine 464 (L464) is critical for regulating D1 and D2 ATPase activity by p97 cofactors p37, p47, and Npl4-Ufd1 (NU). Changing leucine to alanine, proline, or glutamate increased the maximum rate of ATP turnover (kcat) of p47-regulated ATPase activities for these mutants, but not for WT. p37 and p47 increased the kcat of the proline substituted linker, suggesting that they induced linker conformations facilitating ATP hydrolysis. NU inhibited D1 ATPase activities of WT and mutant ND1L proteins, but activated D2 ATPase activity of full-length p97. To further understand the mutant mechanism, we used single-particle cryo-EM to visualize the full-length p97L464P and revealed the conformational change of the D1-D2 linker, resulting in a movement of the helix-turn-helix motif (543-569). Taken together with the biochemical and structural results we conclude that the linker helps maintain D1 in a competent conformation and relays the communication to/from the N-domain to the D1 and D2 ATPase domains, which are ∼50 Å away.
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31
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Božič J, Motaln H, Janež AP, Markič L, Tripathi P, Yamoah A, Aronica E, Lee YB, Heilig R, Fischer R, Thompson AJ, Goswami A, Rogelj B. Interactome screening of C9orf72 dipeptide repeats reveals VCP sequestration and functional impairment by polyGA. Brain 2021; 145:684-699. [PMID: 34534264 PMCID: PMC9014755 DOI: 10.1093/brain/awab300] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 11/25/2022] Open
Abstract
Repeat expansions in the C9orf72 gene are a common cause of amyotrophic lateral sclerosis and frontotemporal lobar degeneration, two devastating neurodegenerative disorders. One of the proposed mechanisms of GGGGCC repeat expansion is their translation into non-canonical dipeptide repeats, which can then accumulate as aggregates and contribute to these pathologies. There are five different dipeptide repeat proteins (polyGA, polyGR, polyPR, polyPA and polyGP), some of which are known to be neurotoxic. In the present study, we used BioID2 proximity labelling to identify the interactomes of all five dipeptide repeat proteins consisting of 125 repeats each. We identified 113 interacting partners for polyGR, 90 for polyGA, 106 for polyPR, 25 for polyPA and 27 for polyGP. Gene Ontology enrichment analysis of the proteomic data revealed that these target interaction partners are involved in a variety of functions, including protein translation, signal transduction pathways, protein catabolic processes, amide metabolic processes and RNA-binding. Using autopsy brain tissue from patients with C9orf72 expansion complemented with cell culture analysis, we evaluated the interactions between polyGA and valosin containing protein (VCP). Functional analysis of this interaction revealed sequestration of VCP with polyGA aggregates, altering levels of soluble valosin-containing protein. VCP also functions in autophagy processes, and consistent with this, we observed altered autophagy in cells expressing polyGA. We also observed altered co-localization of polyGA aggregates and p62 in cells depleted of VCP. All together, these data suggest that sequestration of VCP with polyGA aggregates contributes to the loss of VCP function, and consequently to alterations in autophagy processes in C9orf72 expansion disorders.
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Affiliation(s)
- Janja Božič
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Helena Motaln
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Anja Pucer Janež
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Lara Markič
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Priyanka Tripathi
- Institute of Neuropathology, RWTH Aachen University Medical School, Aachen, Germany
| | - Alfred Yamoah
- Institute of Neuropathology, RWTH Aachen University Medical School, Aachen, Germany
| | - Eleonora Aronica
- Amsterdam UMC, University of Amsterdam, Department of (Neuro) Pathology, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Youn-Bok Lee
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, SE5 8AF, UK
| | - Raphael Heilig
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Roman Fischer
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | - Anand Goswami
- Institute of Neuropathology, RWTH Aachen University Medical School, Aachen, Germany
| | - Boris Rogelj
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia.,Biomedical Research Institute (BRIS), Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
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32
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AAA+ ATPase p97/VCP mutants and inhibitor binding disrupt inter-domain coupling and subsequent allosteric activation. J Biol Chem 2021; 297:101187. [PMID: 34520757 PMCID: PMC8517850 DOI: 10.1016/j.jbc.2021.101187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/31/2021] [Accepted: 09/02/2021] [Indexed: 11/19/2022] Open
Abstract
The human AAA+ ATPase p97, also known as valosin-containing protein, a potential target for cancer therapeutics, plays a vital role in the clearing of misfolded proteins. p97 dysfunction is also known to play a crucial role in several neurodegenerative disorders, such as MultiSystem Proteinopathy 1 (MSP-1) and Familial Amyotrophic Lateral Sclerosis (ALS). However, the structural basis of its role in such diseases remains elusive. Here, we present cryo-EM structural analyses of four disease mutants p97R155H, p97R191Q, p97A232E, p97D592N, as well as p97E470D, implicated in resistance to the drug CB-5083, a potent p97 inhibitor. Our cryo-EM structures demonstrate that these mutations affect nucleotide-driven allosteric activation across the three principal p97 domains (N, D1, and D2) by predominantly interfering with either (1) the coupling between the D1 and N-terminal domains (p97R155H and p97R191Q), (2) the interprotomer interactions (p97A232E), or (3) the coupling between D1 and D2 nucleotide domains (p97D592N, p97E470D). We also show that binding of the competitive inhibitor, CB-5083, to the D2 domain prevents conformational changes similar to those seen for mutations that affect coupling between the D1 and D2 domains. Our studies enable tracing of the path of allosteric activation across p97 and establish a common mechanistic link between active site inhibition and defects in allosteric activation by disease-causing mutations and have potential implications for the design of novel allosteric compounds that can modulate p97 function.
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33
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Nandi P, Li S, Columbres RCA, Wang F, Williams DR, Poh YP, Chou TF, Chiu PL. Structural and Functional Analysis of Disease-Linked p97 ATPase Mutant Complexes. Int J Mol Sci 2021; 22:ijms22158079. [PMID: 34360842 PMCID: PMC8347982 DOI: 10.3390/ijms22158079] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/22/2021] [Accepted: 07/25/2021] [Indexed: 01/14/2023] Open
Abstract
IBMPFD/ALS is a genetic disorder caused by a single amino acid mutation on the p97 ATPase, promoting ATPase activity and cofactor dysregulation. The disease mechanism underlying p97 ATPase malfunction remains unclear. To understand how the mutation alters the ATPase regulation, we assembled a full-length p97R155H with its p47 cofactor and first visualized their structures using single-particle cryo-EM. More than one-third of the population was the dodecameric form. Nucleotide presence dissociates the dodecamer into two hexamers for its highly elevated function. The N-domains of the p97R155H mutant all show up configurations in ADP- or ATPγS-bound states. Our functional and structural analyses showed that the p47 binding is likely to impact the p97R155H ATPase activities via changing the conformations of arginine fingers. These functional and structural analyses underline the ATPase dysregulation with the miscommunication between the functional modules of the p97R155H.
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Affiliation(s)
- Purbasha Nandi
- Biodesign Center for Applied Structural Discovery, School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA;
| | - Shan Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; (S.L.); (R.C.A.C.); (F.W.); (Y.-P.P.)
| | - Rod Carlo A. Columbres
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; (S.L.); (R.C.A.C.); (F.W.); (Y.-P.P.)
| | - Feng Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; (S.L.); (R.C.A.C.); (F.W.); (Y.-P.P.)
| | | | - Yu-Ping Poh
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; (S.L.); (R.C.A.C.); (F.W.); (Y.-P.P.)
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; (S.L.); (R.C.A.C.); (F.W.); (Y.-P.P.)
- Correspondence: (T.-F.C.); (P.-L.C.)
| | - Po-Lin Chiu
- Biodesign Center for Applied Structural Discovery, School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA;
- Correspondence: (T.-F.C.); (P.-L.C.)
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34
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Wani A, Zhu J, Ulrich JD, Eteleeb A, Sauerbeck AD, Reitz SJ, Arhzaouy K, Ikenaga C, Yuede CM, Pittman SK, Wang F, Li S, Benitez BA, Cruchaga C, Kummer TT, Harari O, Chou TF, Schröder R, Clemen CS, Weihl CC. Neuronal VCP loss of function recapitulates FTLD-TDP pathology. Cell Rep 2021; 36:109399. [PMID: 34289347 PMCID: PMC8383344 DOI: 10.1016/j.celrep.2021.109399] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/06/2021] [Accepted: 06/22/2021] [Indexed: 12/12/2022] Open
Abstract
The pathogenic mechanism by which dominant mutations in VCP cause multisystem proteinopathy (MSP), a rare neurodegenerative disease that presents as fronto-temporal lobar degeneration with TDP-43 inclusions (FTLD-TDP), remains unclear. To explore this, we inactivate VCP in murine postnatal forebrain neurons (VCP conditional knockout [cKO]). VCP cKO mice have cortical brain atrophy, neuronal loss, autophago-lysosomal dysfunction, and TDP-43 inclusions resembling FTLD-TDP pathology. Conditional expression of a single disease-associated mutation, VCP-R155C, in a VCP null background similarly recapitulates features of VCP inactivation and FTLD-TDP, suggesting that this MSP mutation is hypomorphic. Comparison of transcriptomic and proteomic datasets from genetically defined patients with FTLD-TDP reveal that progranulin deficiency and VCP insufficiency result in similar profiles. These data identify a loss of VCP-dependent functions as a mediator of FTLD-TDP and reveal an unexpected biochemical similarity with progranulin deficiency.
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Affiliation(s)
- Abubakar Wani
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Jiang Zhu
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Jason D Ulrich
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Abdallah Eteleeb
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Andrew D Sauerbeck
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Sydney J Reitz
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Khalid Arhzaouy
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Chiseko Ikenaga
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Carla M Yuede
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Sara K Pittman
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Feng Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Shan Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Bruno A Benitez
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Carlos Cruchaga
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Terrance T Kummer
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Oscar Harari
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, Friedrich Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph S Clemen
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany; Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany
| | - Conrad C Weihl
- Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO, USA.
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35
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Mechanistic insight into substrate processing and allosteric inhibition of human p97. Nat Struct Mol Biol 2021; 28:614-625. [PMID: 34262183 DOI: 10.1038/s41594-021-00617-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/04/2021] [Indexed: 02/06/2023]
Abstract
p97 processes ubiquitinated substrates and plays a central role in cellular protein homeostasis. Here, we report a series of cryo-EM structures of the substrate-engaged human p97 complex with resolutions ranging from 2.9 to 3.8 Å that captured 'power-stroke'-like motions of both the D1 and D2 ATPase rings of p97. A key feature of these structures is the critical conformational changes of the intersubunit signaling (ISS) motifs, which tighten the binding of nucleotides and neighboring subunits and contribute to the spiral staircase conformation of the D1 and D2 rings. In addition, we determined the cryo-EM structure of human p97 in complex with NMS-873, a potent p97 inhibitor, at a resolution of 2.4 Å. The structures showed that NMS-873 binds at a cryptic groove in the D2 domain and interacts with the ISS motif, preventing its conformational change and thus blocking substrate translocation allosterically.
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Root J, Merino P, Nuckols A, Johnson M, Kukar T. Lysosome dysfunction as a cause of neurodegenerative diseases: Lessons from frontotemporal dementia and amyotrophic lateral sclerosis. Neurobiol Dis 2021; 154:105360. [PMID: 33812000 PMCID: PMC8113138 DOI: 10.1016/j.nbd.2021.105360] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 03/16/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022] Open
Abstract
Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are fatal neurodegenerative disorders that are thought to exist on a clinical and pathological spectrum. FTD and ALS are linked by shared genetic causes (e.g. C9orf72 hexanucleotide repeat expansions) and neuropathology, such as inclusions of ubiquitinated, misfolded proteins (e.g. TAR DNA-binding protein 43; TDP-43) in the CNS. Furthermore, some genes that cause FTD or ALS when mutated encode proteins that localize to the lysosome or modulate endosome-lysosome function, including lysosomal fusion, cargo trafficking, lysosomal acidification, autophagy, or TFEB activity. In this review, we summarize evidence that lysosomal dysfunction, caused by genetic mutations (e.g. C9orf72, GRN, MAPT, TMEM106B) or toxic-gain of function (e.g. aggregation of TDP-43 or tau), is an important pathogenic disease mechanism in FTD and ALS. Further studies into the normal function of many of these proteins are required and will help uncover the mechanisms that cause lysosomal dysfunction in FTD and ALS. Mutations or polymorphisms in genes that encode proteins important for endosome-lysosome function also occur in other age-dependent neurodegenerative diseases, including Alzheimer's (e.g. APOE, PSEN1, APP) and Parkinson's (e.g. GBA, LRRK2, ATP13A2) disease. A more complete understanding of the common and unique features of lysosome dysfunction across the spectrum of neurodegeneration will help guide the development of therapies for these devastating diseases.
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Affiliation(s)
- Jessica Root
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Paola Merino
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Austin Nuckols
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Michelle Johnson
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Thomas Kukar
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia; Department of Neurology, Emory University, School of Medicine, Atlanta 30322, Georgia.
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Creekmore BC, Chang YW, Lee EB. The Cryo-EM Effect: Structural Biology of Neurodegenerative Disease Proteostasis Factors. J Neuropathol Exp Neurol 2021; 80:494-513. [PMID: 33860329 DOI: 10.1093/jnen/nlab029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neurodegenerative diseases are characterized by the accumulation of misfolded proteins. This protein aggregation suggests that abnormal proteostasis contributes to aging-related neurodegeneration. A better fundamental understanding of proteins that regulate proteostasis may provide insight into the pathophysiology of neurodegenerative disease and may perhaps reveal novel therapeutic opportunities. The 26S proteasome is the key effector of the ubiquitin-proteasome system responsible for degrading polyubiquitinated proteins. However, additional factors, such as valosin-containing protein (VCP/p97/Cdc48) and C9orf72, play a role in regulation and trafficking of substrates through the normal proteostasis systems of a cell. Nonhuman AAA+ ATPases, such as the disaggregase Hsp104, also provide insights into the biochemical processes that regulate protein aggregation. X-ray crystallography and cryo-electron microscopy (cryo-EM) structures not bound to substrate have provided meaningful information about the 26S proteasome, VCP, and Hsp104. However, recent cryo-EM structures bound to substrate have provided new information about the function and mechanism of these proteostasis factors. Cryo-EM and cryo-electron tomography data combined with biochemical data have also increased the understanding of C9orf72 and its role in maintaining proteostasis. These structural insights provide a foundation for understanding proteostasis mechanisms with near-atomic resolution upon which insights can be gleaned regarding the pathophysiology of neurodegenerative diseases.
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Affiliation(s)
- Benjamin C Creekmore
- From the Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi-Wei Chang
- From the Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Edward B Lee
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Jessop M, Felix J, Gutsche I. AAA+ ATPases: structural insertions under the magnifying glass. Curr Opin Struct Biol 2021; 66:119-128. [PMID: 33246198 PMCID: PMC7973254 DOI: 10.1016/j.sbi.2020.10.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/19/2020] [Accepted: 10/27/2020] [Indexed: 11/29/2022]
Abstract
AAA+ ATPases are a diverse protein superfamily which power a vast number of cellular processes, from protein degradation to genome replication and ribosome biogenesis. The latest advances in cryo-EM have resulted in a spectacular increase in the number and quality of AAA+ ATPase structures. This abundance of new information enables closer examination of different types of structural insertions into the conserved core, revealing discrepancies in the current classification of AAA+ modules into clades. Additionally, combined with biochemical data, it has allowed rapid progress in our understanding of structure-functional relationships and provided arguments both in favour and against the existence of a unifying molecular mechanism for the ATPase activity and action on substrates, stimulating further intensive research.
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Affiliation(s)
- Matthew Jessop
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044 Grenoble, France.
| | - Jan Felix
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044 Grenoble, France
| | - Irina Gutsche
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044 Grenoble, France.
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Nguyen T, Urrutia-Cabrera D, Liou RHC, Luu CD, Guymer R, Wong RCB. New Technologies to Study Functional Genomics of Age-Related Macular Degeneration. Front Cell Dev Biol 2021; 8:604220. [PMID: 33505962 PMCID: PMC7829507 DOI: 10.3389/fcell.2020.604220] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 12/07/2020] [Indexed: 12/18/2022] Open
Abstract
Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss in people over 50 years old in developed countries. Currently, we still lack a comprehensive understanding of the genetic factors contributing to AMD, which is critical to identify effective therapeutic targets to improve treatment outcomes for AMD patients. Here we discuss the latest technologies that can facilitate the identification and functional study of putative genes in AMD pathology. We review improved genomic methods to identify novel AMD genes, advances in single cell transcriptomics to profile gene expression in specific retinal cell types, and summarize recent development of in vitro models for studying AMD using induced pluripotent stem cells, organoids and biomaterials, as well as new molecular technologies using CRISPR/Cas that could facilitate functional studies of AMD-associated genes.
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Affiliation(s)
- Tu Nguyen
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Daniel Urrutia-Cabrera
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Roxanne Hsiang-Chi Liou
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Chi D Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Robyn Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Raymond Ching-Bong Wong
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
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Pan M, Zheng Q, Yu Y, Ai H, Xie Y, Zeng X, Wang C, Liu L, Zhao M. Seesaw conformations of Npl4 in the human p97 complex and the inhibitory mechanism of a disulfiram derivative. Nat Commun 2021; 12:121. [PMID: 33402676 PMCID: PMC7785736 DOI: 10.1038/s41467-020-20359-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 11/25/2020] [Indexed: 01/29/2023] Open
Abstract
p97, also known as valosin-containing protein (VCP) or Cdc48, plays a central role in cellular protein homeostasis. Human p97 mutations are associated with several neurodegenerative diseases. Targeting p97 and its cofactors is a strategy for cancer drug development. Despite significant structural insights into the fungal homolog Cdc48, little is known about how human p97 interacts with its cofactors. Recently, the anti-alcohol abuse drug disulfiram was found to target cancer through Npl4, a cofactor of p97, but the molecular mechanism remains elusive. Here, using single-particle cryo-electron microscopy (cryo-EM), we uncovered three Npl4 conformational states in complex with human p97 before ATP hydrolysis. The motion of Npl4 results from its zinc finger motifs interacting with the N domain of p97, which is essential for the unfolding activity of p97. In vitro and cell-based assays showed that the disulfiram derivative bis-(diethyldithiocarbamate)-copper (CuET) can bypass the copper transporter system and inhibit the function of p97 in the cytoplasm by releasing cupric ions under oxidative conditions, which disrupt the zinc finger motifs of Npl4, locking the essential conformational switch of the complex.
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Affiliation(s)
- Man Pan
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Qingyun Zheng
- Tsinghua-Peking Center for Life Sciences, Department of Chemistry, Tsinghua University, 100084, Beijing, China
| | - Yuanyuan Yu
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Huasong Ai
- Tsinghua-Peking Center for Life Sciences, Department of Chemistry, Tsinghua University, 100084, Beijing, China
| | - Yuan Xie
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Xin Zeng
- Peking-Tsinghua Center for Life Sciences, College of Chemistry and Molecular Engineering, Peking University, 100871, Beijing, China
| | - Chu Wang
- Peking-Tsinghua Center for Life Sciences, College of Chemistry and Molecular Engineering, Peking University, 100871, Beijing, China
| | - Lei Liu
- Tsinghua-Peking Center for Life Sciences, Department of Chemistry, Tsinghua University, 100084, Beijing, China.
| | - Minglei Zhao
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA.
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Polymerase delta-interacting protein 38 (PDIP38) modulates the stability and activity of the mitochondrial AAA+ protease CLPXP. Commun Biol 2020; 3:646. [PMID: 33159171 PMCID: PMC7647994 DOI: 10.1038/s42003-020-01358-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 10/09/2020] [Indexed: 02/06/2023] Open
Abstract
Over a decade ago Polymerase δ interacting protein of 38 kDa (PDIP38) was proposed to play a role in DNA repair. Since this time, both the physiological function and subcellular location of PDIP38 has remained ambiguous and our present understanding of PDIP38 function has been hampered by a lack of detailed biochemical and structural studies. Here we show, that human PDIP38 is directed to the mitochondrion in a membrane potential dependent manner, where it resides in the matrix compartment, together with its partner protein CLPX. Our structural analysis revealed that PDIP38 is composed of two conserved domains separated by an α/β linker region. The N-terminal (YccV-like) domain of PDIP38 forms an SH3-like β-barrel, which interacts specifically with CLPX, via the adaptor docking loop within the N-terminal Zinc binding domain of CLPX. In contrast, the C-terminal (DUF525) domain forms an immunoglobin-like β-sandwich fold, which contains a highly conserved putative substrate binding pocket. Importantly, PDIP38 modulates the substrate specificity of CLPX and protects CLPX from LONM-mediated degradation, which stabilises the cellular levels of CLPX. Collectively, our findings shed new light on the mechanism and function of mitochondrial PDIP38, demonstrating that PDIP38 is a bona fide adaptor protein for the mitochondrial protease, CLPXP. Strack et al find that Polymerase δ interacting protein 38 (PDIP38) is targeted to the mitochondrial matrix where it colocalises with the mitochondrial AAA + protein CLPXP. PDIP38 modulates the specificity of CLPXP in vitro and alters the stability of CLPX in vitro and in cells. The PDIP38 structure leads the authors to speculate that PDIP38 is a CLPXP adaptor.
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42
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Glynn SE, Kardon JR, Mueller-Cajar O, Cho C. AAA+ proteins: converging mechanisms, diverging functions. Nat Struct Mol Biol 2020; 27:515-518. [PMID: 32461632 DOI: 10.1038/s41594-020-0444-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Steven E Glynn
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA.
| | - Julia R Kardon
- Department of Biochemistry, Brandeis University, Waltham, MA, USA.
| | - Oliver Mueller-Cajar
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
| | - Carol Cho
- Research Center for Natural Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
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43
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Darwich NF, Phan JM, Kim B, Suh E, Papatriantafyllou JD, Changolkar L, Nguyen AT, O'Rourke CM, He Z, Porta S, Gibbons GS, Luk KC, Papageorgiou SG, Grossman M, Massimo L, Irwin DJ, McMillan CT, Nasrallah IM, Toro C, Aguirre GK, Van Deerlin VM, Lee EB. Autosomal dominant VCP hypomorph mutation impairs disaggregation of PHF-tau. Science 2020; 370:science.aay8826. [PMID: 33004675 DOI: 10.1126/science.aay8826] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 07/16/2020] [Accepted: 09/17/2020] [Indexed: 12/15/2022]
Abstract
Neurodegeneration in Alzheimer's disease (AD) is closely associated with the accumulation of pathologic tau aggregates in the form of neurofibrillary tangles. We found that a p.Asp395Gly mutation in VCP (valosin-containing protein) was associated with dementia characterized neuropathologically by neuronal vacuoles and neurofibrillary tangles. Moreover, VCP appeared to exhibit tau disaggregase activity in vitro, which was impaired by the p.Asp395Gly mutation. Additionally, intracerebral microinjection of pathologic tau led to increased tau aggregates in mice in which p.Asp395Gly VCP mice was knocked in, as compared with injected wild-type mice. These findings suggest that p.Asp395Gly VCP is an autosomal-dominant genetic mutation associated with neurofibrillary degeneration in part owing to reduced tau disaggregation, raising the possibility that VCP may represent a therapeutic target for the treatment of AD.
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Affiliation(s)
- Nabil F Darwich
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Jessica M Phan
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Boram Kim
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - EunRan Suh
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - John D Papatriantafyllou
- Medical Center of Athens, Memory Disorders Clinic and Day Care Center for Third Age "IASIS," Athens, Greece
| | - Lakshmi Changolkar
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Aivi T Nguyen
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Caroline M O'Rourke
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Zhuohao He
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Sílvia Porta
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Garrett S Gibbons
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Kelvin C Luk
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Sokratis G Papageorgiou
- First University Department of Neurology, Eginiteio University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Murray Grossman
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Lauren Massimo
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - David J Irwin
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Corey T McMillan
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Ilya M Nasrallah
- Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Camilo Toro
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, MD, USA
| | - Geoffrey K Aguirre
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Vivianna M Van Deerlin
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA
| | - Edward B Lee
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, PA, USA.
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Rydzek S, Shein M, Bielytskyi P, Schütz AK. Observation of a Transient Reaction Intermediate Illuminates the Mechanochemical Cycle of the AAA-ATPase p97. J Am Chem Soc 2020; 142:14472-14480. [DOI: 10.1021/jacs.0c03180] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Simon Rydzek
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, 85748 Garching, Germany
| | - Mikhail Shein
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, 85748 Garching, Germany
| | - Pavlo Bielytskyi
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, 85748 Garching, Germany
| | - Anne K. Schütz
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, 85748 Garching, Germany
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
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45
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Proteasome Inhibitors: Harnessing Proteostasis to Combat Disease. Molecules 2020; 25:molecules25030671. [PMID: 32033280 PMCID: PMC7037493 DOI: 10.3390/molecules25030671] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/25/2020] [Accepted: 01/28/2020] [Indexed: 02/07/2023] Open
Abstract
The proteasome is the central component of the main cellular protein degradation pathway. During the past four decades, the critical function of the proteasome in numerous physiological processes has been revealed, and proteasome activity has been linked to various human diseases. The proteasome prevents the accumulation of misfolded proteins, controls the cell cycle, and regulates the immune response, to name a few important roles for this macromolecular "machine." As a therapeutic target, proteasome inhibitors have been approved for the treatment of multiple myeloma and mantle cell lymphoma. However, inability to sufficiently inhibit proteasome activity at tolerated doses has hampered efforts to expand the scope of proteasome inhibitor-based therapies. With emerging new modalities in myeloma, it might seem challenging to develop additional proteasome-based therapies. However, the constant development of new applications for proteasome inhibitors and deeper insights into the intricacies of protein homeostasis suggest that proteasome inhibitors might have novel therapeutic applications. Herein, we summarize the latest advances in proteasome inhibitor development and discuss the future of proteasome inhibitors and other proteasome-based therapies in combating human diseases.
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Probing Proteostatic Stress in Degenerating Photoreceptors Using Two Complementary In Vivo Reporters of Proteasomal Activity. eNeuro 2019; 7:ENEURO.0428-19.2019. [PMID: 31826915 PMCID: PMC6948925 DOI: 10.1523/eneuro.0428-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/02/2019] [Accepted: 12/04/2019] [Indexed: 12/01/2022] Open
Abstract
Inherited retinal degenerations originate from mutations in >300 genes, many of which cause the production of misfolded mutant photoreceptor proteins that are ultimately degraded by the ubiquitin-proteasome system (UPS). It was previously shown that rod photoreceptors in multiple mouse models of retinal degeneration suffer from proteostatic stress consisting of an insufficient cellular capacity for degrading UPS substrates. In this study, we focused on a specific UPS component required for the degradation of a subset of proteasome targets: the substrate-processing complex formed by the AAA+ ATPase P97/VCP and associated cofactors. To assess whether P97 capacity may be insufficient in degenerating rods, we employed two complementary in vivo proteasomal activity reporters whose degradation is either P97-dependent or P97-independent. Retinal accumulation of each reporter was measured in two models of retinal degeneration: the transducin γ-subunit knock-out (Gγ1-/-) and P23H rhodopsin knock-in (P23H) mice. Strikingly, the patterns of reporter accumulation differed between these models, indicating that the proteostatic stress observed in Gγ1-/- and P23H rods likely originates from different pathobiological mechanisms, in which UPS substrate degradation may or may not be limited by P97-dependent substrate processing. Further, we assessed whether P97 overexpression could ameliorate pathology in Gγ1-/- mice, in which proteostatic stress appears to result from P97 insufficiency. However, despite P97 overexpression being aphenotypic in other tissues, the ∼2.4-fold increase in retinal P97 content was toxic to rods, which complicated the interpretation of the observed phenotype. Our results highlight the complexity of pathophysiological mechanisms related to degrading misfolded proteins in mutant photoreceptors.
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