1
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Frachon N, Demaretz S, Seaayfan E, Chelbi L, Bakhos-Douaihy D, Laghmani K. AUP1 Regulates the Endoplasmic Reticulum-Associated Degradation and Polyubiquitination of NKCC2. Cells 2024; 13:389. [PMID: 38474353 DOI: 10.3390/cells13050389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 01/30/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024] Open
Abstract
Inactivating mutations of kidney Na-K-2Cl cotransporter NKCC2 lead to antenatal Bartter syndrome (BS) type 1, a life-threatening salt-losing tubulopathy. We previously reported that this serious inherited renal disease is linked to the endoplasmic reticulum-associated degradation (ERAD) pathway. The purpose of this work is to characterize further the ERAD machinery of NKCC2. Here, we report the identification of ancient ubiquitous protein 1 (AUP1) as a novel interactor of NKCC2 ER-resident form in renal cells. AUP1 is also an interactor of the ER lectin OS9, a key player in the ERAD of NKCC2. Similar to OS9, AUP1 co-expression decreased the amount of total NKCC2 protein by enhancing the ER retention and associated protein degradation of the cotransporter. Blocking the ERAD pathway with the proteasome inhibitor MG132 or the α-mannosidase inhibitor kifunensine fully abolished the AUP1 effect on NKCC2. Importantly, AUP1 knock-down or inhibition by overexpressing its dominant negative form strikingly decreased NKCC2 polyubiquitination and increased the protein level of the cotransporter. Interestingly, AUP1 co-expression produced a more profound impact on NKCC2 folding mutants. Moreover, AUP1 also interacted with the related kidney cotransporter NCC and downregulated its expression, strongly indicating that AUP1 is a common regulator of sodium-dependent chloride cotransporters. In conclusion, our data reveal the presence of an AUP1-mediated pathway enhancing the polyubiquitination and ERAD of NKCC2. The characterization and selective regulation of specific ERAD constituents of NKCC2 and its pathogenic mutants could open new avenues in the therapeutic strategies for type 1 BS treatment.
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Affiliation(s)
- Nadia Frachon
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS, ERL8228, F-75006 Paris, France
| | - Sylvie Demaretz
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS, ERL8228, F-75006 Paris, France
| | - Elie Seaayfan
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS, ERL8228, F-75006 Paris, France
| | - Lydia Chelbi
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS, ERL8228, F-75006 Paris, France
| | - Dalal Bakhos-Douaihy
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS, ERL8228, F-75006 Paris, France
| | - Kamel Laghmani
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS, ERL8228, F-75006 Paris, France
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2
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Avci D, Heidasch R, Costa M, Lüchtenborg C, Kale D, Brügger B, Lemberg MK. Intramembrane protease SPP defines a cholesterol-regulated abundance control of the mevalonate pathway enzyme squalene synthase. J Biol Chem 2024; 300:105644. [PMID: 38218226 PMCID: PMC10850959 DOI: 10.1016/j.jbc.2024.105644] [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: 05/24/2023] [Revised: 12/21/2023] [Accepted: 01/02/2024] [Indexed: 01/15/2024] Open
Abstract
Intramembrane proteolysis regulates important processes such as signaling and transcriptional and posttranslational abundance control of proteins with key functions in metabolic pathways. This includes transcriptional control of mevalonate pathway genes, thereby ensuring balanced biosynthesis of cholesterol and other isoprenoids. Our work shows that, at high cholesterol levels, signal peptide peptidase (SPP) cleaves squalene synthase (SQS), an enzyme that defines the branching point for allocation of isoprenoids to the sterol and nonsterol arms of the mevalonate pathway. This intramembrane cleavage releases SQS from the membrane and targets it for proteasomal degradation. Regulation of this mechanism is achieved by the E3 ubiquitin ligase TRC8 that, in addition to ubiquitinating SQS in response to cholesterol levels, acts as an allosteric activator of SPP-catalyzed intramembrane cleavage of SQS. Cellular cholesterol levels increase in the absence of SPP activity. We infer from these results that, SPP-TRC8 mediated abundance control of SQS acts as a regulation step within the mevalonate pathway.
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Affiliation(s)
- Dönem Avci
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
| | - Ronny Heidasch
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Martina Costa
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | | | - Dipali Kale
- Biochemistry Center of Heidelberg University (BZH), Heidelberg, Germany
| | - Britta Brügger
- Biochemistry Center of Heidelberg University (BZH), Heidelberg, Germany
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
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3
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Botsch JJ, Junker R, Sorgenfrei M, Ogger PP, Stier L, von Gronau S, Murray PJ, Seeger MA, Schulman BA, Bräuning B. Doa10/MARCH6 architecture interconnects E3 ligase activity with lipid-binding transmembrane channel to regulate SQLE. Nat Commun 2024; 15:410. [PMID: 38195637 PMCID: PMC10776854 DOI: 10.1038/s41467-023-44670-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 12/19/2023] [Indexed: 01/11/2024] Open
Abstract
Transmembrane E3 ligases play crucial roles in homeostasis. Much protein and organelle quality control, and metabolic regulation, are determined by ER-resident MARCH6 E3 ligases, including Doa10 in yeast. Here, we present Doa10/MARCH6 structural analysis by cryo-EM and AlphaFold predictions, and a structure-based mutagenesis campaign. The majority of Doa10/MARCH6 adopts a unique circular structure within the membrane. This channel is established by a lipid-binding scaffold, and gated by a flexible helical bundle. The ubiquitylation active site is positioned over the channel by connections between the cytosolic E3 ligase RING domain and the membrane-spanning scaffold and gate. Here, by assaying 95 MARCH6 variants for effects on stability of the well-characterized substrate SQLE, which regulates cholesterol levels, we reveal crucial roles of the gated channel and RING domain consistent with AlphaFold-models of substrate-engaged and ubiquitylation complexes. SQLE degradation further depends on connections between the channel and RING domain, and lipid binding sites, revealing how interconnected Doa10/MARCH6 elements could orchestrate metabolic signals, substrate binding, and E3 ligase activity.
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Affiliation(s)
- J Josephine Botsch
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
- Technical University of Munich, School of Natural Sciences, Munich, Germany
| | - Roswitha Junker
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Michèle Sorgenfrei
- Institute of Medical Microbiology, University of Zurich, Gloriastrasse 28/30, 8006, Zurich, Switzerland
| | - Patricia P Ogger
- Research Group of Immunoregulation, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Luca Stier
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
- Technical University of Munich, School of Natural Sciences, Munich, Germany
| | - Susanne von Gronau
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Peter J Murray
- Research Group of Immunoregulation, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Markus A Seeger
- Institute of Medical Microbiology, University of Zurich, Gloriastrasse 28/30, 8006, Zurich, Switzerland
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.
| | - Bastian Bräuning
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.
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4
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Mentrup T, Leinung N, Patel M, Fluhrer R, Schröder B. The role of SPP/SPPL intramembrane proteases in membrane protein homeostasis. FEBS J 2024; 291:25-44. [PMID: 37625440 DOI: 10.1111/febs.16941] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/03/2023] [Accepted: 08/23/2023] [Indexed: 08/27/2023]
Abstract
Signal peptide peptidase (SPP) and the four SPP-like proteases SPPL2a, SPPL2b, SPPL2c and SPPL3 constitute a family of aspartyl intramembrane proteases with homology to presenilins. The different members reside in distinct cellular localisations within the secretory pathway and the endo-lysosomal system. Despite individual cleavage characteristics, they all cleave single-span transmembrane proteins with a type II orientation exhibiting a cytosolic N-terminus. Though the identification of substrates is not complete, SPP/SPPL-mediated proteolysis appears to be rather selective. Therefore, according to our current understanding cleavage by SPP/SPPL proteases rather seems to serve a regulatory function than being a bulk proteolytic pathway. In the present review, we will summarise our state of knowledge on SPP/SPPL proteases and in particular highlight recently identified substrates and the functional and/or (patho)-physiological implications of these cleavage events. Based on this, we aim to provide an overview of the current open questions in the field. These are connected to the regulation of these proteases at the cellular level but also in context of disease and patho-physiological processes. Furthermore, the interplay with other proteostatic systems capable of degrading membrane proteins is beginning to emerge.
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Affiliation(s)
- Torben Mentrup
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
| | - Nadja Leinung
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
| | - Mehul Patel
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Germany
- Center for Interdisciplinary Health Research, University of Augsburg, Germany
| | - Bernd Schröder
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
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5
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Gawden-Bone CM, Lehner PJ, Volkmar N. As a matter of fat: Emerging roles of lipid-sensitive E3 ubiquitin ligases. Bioessays 2023; 45:e2300139. [PMID: 37890275 DOI: 10.1002/bies.202300139] [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: 07/28/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 10/29/2023]
Abstract
The dynamic structure and composition of lipid membranes need to be tightly regulated to control the vast array of cellular processes from cell and organelle morphology to protein-protein interactions and signal transduction pathways. To maintain membrane integrity, sense-and-response systems monitor and adjust membrane lipid composition to the ever-changing cellular environment, but only a relatively small number of control systems have been described. Here, we explore the emerging role of the ubiquitin-proteasome system in monitoring and maintaining membrane lipid composition. We focus on the ER-resident RNF145 E3 ubiquitin ligase, its role in regulating adiponectin receptor 2 (ADIPOR2), its lipid hydrolase substrate, and the broader implications for understanding the homeostatic processes that fine-tune cellular membrane composition.
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Affiliation(s)
- Christian M Gawden-Bone
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, UK
| | - Paul J Lehner
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, UK
| | - Norbert Volkmar
- Institute for Molecular Systems Biology (IMSB), ETH Zürich, Zürich, Switzerland
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6
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Yang J, Lee Y, Hwang CS. The ubiquitin-proteasome system links NADPH metabolism to ferroptosis. Trends Cell Biol 2023; 33:1088-1103. [PMID: 37558595 DOI: 10.1016/j.tcb.2023.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/07/2023] [Accepted: 07/11/2023] [Indexed: 08/11/2023]
Abstract
Ferroptosis is the type of cell death arising from uncontrolled and excessive lipid peroxidation. NADPH is essential for ferroptosis regulation because it supplies reducing equivalents for antioxidant defense systems and contributes to the generation of reactive oxygen species. Moreover, NADPH level serves as a biomarker for predicting the sensitivity of cells to ferroptosis. The ubiquitin-proteasome system governs the stability of many ferroptosis effectors. Recent research has revealed MARCHF6, the endoplasmic reticulum ubiquitin ligase, as an unprecedented NADPH sensor in the ubiquitin system and a critical regulator of ferroptosis involved in tumorigenesis and fetal development. This review summarizes the current understanding of NADPH metabolism and the ubiquitin-proteasome system in regulating ferroptosis and highlights the emerging importance of MARCHF6 as a vital connector between NADPH metabolism and ferroptosis.
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Affiliation(s)
- Jihye Yang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Yoontae Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Cheol-Sang Hwang
- Department of Life Sciences, Korea University, Seoul, Republic of Korea.
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7
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Christianson JC, Jarosch E, Sommer T. Mechanisms of substrate processing during ER-associated protein degradation. Nat Rev Mol Cell Biol 2023; 24:777-796. [PMID: 37528230 DOI: 10.1038/s41580-023-00633-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2023] [Indexed: 08/03/2023]
Abstract
Maintaining proteome integrity is essential for long-term viability of all organisms and is overseen by intrinsic quality control mechanisms. The secretory pathway of eukaryotes poses a challenge for such quality assurance as proteins destined for secretion enter the endoplasmic reticulum (ER) and become spatially segregated from the cytosolic machinery responsible for disposal of aberrant (misfolded or otherwise damaged) or superfluous polypeptides. The elegant solution provided by evolution is ER-membrane-bound ubiquitylation machinery that recognizes misfolded or surplus proteins or by-products of protein biosynthesis in the ER and delivers them to 26S proteasomes for degradation. ER-associated protein degradation (ERAD) collectively describes this specialized arm of protein quality control via the ubiquitin-proteasome system. But, instead of providing a single strategy to remove defective or unwanted proteins, ERAD represents a collection of independent processes that exhibit distinct yet overlapping selectivity for a wide range of substrates. Not surprisingly, ER-membrane-embedded ubiquitin ligases (ER-E3s) act as central hubs for each of these separate ERAD disposal routes. In these processes, ER-E3s cooperate with a plethora of specialized factors, coordinating recognition, transport and ubiquitylation of undesirable secretory, membrane and cytoplasmic proteins. In this Review, we focus on substrate processing during ERAD, highlighting common threads as well as differences between the many routes via ERAD.
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Affiliation(s)
- John C Christianson
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
| | - Ernst Jarosch
- Max-Delbrück-Centrer for Molecular Medicine in Helmholtz Association, Berlin-Buch, Germany
| | - Thomas Sommer
- Max-Delbrück-Centrer for Molecular Medicine in Helmholtz Association, Berlin-Buch, Germany.
- Institute for Biology, Humboldt Universität zu Berlin, Berlin, Germany.
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8
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Roberts MA, Deol KK, Mathiowetz AJ, Lange M, Leto DE, Stevenson J, Hashemi SH, Morgens DW, Easter E, Heydari K, Nalls MA, Bassik MC, Kampmann M, Kopito RR, Faghri F, Olzmann JA. Parallel CRISPR-Cas9 screens identify mechanisms of PLIN2 and lipid droplet regulation. Dev Cell 2023; 58:1782-1800.e10. [PMID: 37494933 PMCID: PMC10530302 DOI: 10.1016/j.devcel.2023.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 06/01/2023] [Accepted: 07/03/2023] [Indexed: 07/28/2023]
Abstract
Despite the key roles of perilipin-2 (PLIN2) in governing lipid droplet (LD) metabolism, the mechanisms that regulate PLIN2 levels remain incompletely understood. Here, we leverage a set of genome-edited human PLIN2 reporter cell lines in a series of CRISPR-Cas9 loss-of-function screens, identifying genetic modifiers that influence PLIN2 expression and post-translational stability under different metabolic conditions and in different cell types. These regulators include canonical genes that control lipid metabolism as well as genes involved in ubiquitination, transcription, and mitochondrial function. We further demonstrate a role for the E3 ligase MARCH6 in regulating triacylglycerol biosynthesis, thereby influencing LD abundance and PLIN2 stability. Finally, our CRISPR screens and several published screens provide the foundation for CRISPRlipid (http://crisprlipid.org), an online data commons for lipid-related functional genomics data. Our study identifies mechanisms of PLIN2 and LD regulation and provides an extensive resource for the exploration of LD biology and lipid metabolism.
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Affiliation(s)
- Melissa A Roberts
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kirandeep K Deol
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Alyssa J Mathiowetz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Mike Lange
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Dara E Leto
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Julian Stevenson
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Sayed Hadi Hashemi
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL 61820, USA
| | - David W Morgens
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Emilee Easter
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kartoosh Heydari
- Cancer Research Laboratory FACS Core Facility, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Mike A Nalls
- Data Tecnica International, LLC, Washington, DC, USA; Center for Alzheimer's and Related Dementias, National Institutes of Health, Bethesda, MD 20892, USA; Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
| | - Michael C Bassik
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Martin Kampmann
- Institute for Neurodegenerative Diseases, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ron R Kopito
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Faraz Faghri
- Data Tecnica International, LLC, Washington, DC, USA; Center for Alzheimer's and Related Dementias, National Institutes of Health, Bethesda, MD 20892, USA; Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
| | - James A Olzmann
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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9
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Dickson AS, Pauzaite T, Arnaiz E, Ortmann BM, West JA, Volkmar N, Martinelli AW, Li Z, Wit N, Vitkup D, Kaser A, Lehner PJ, Nathan JA. A HIF independent oxygen-sensitive pathway for controlling cholesterol synthesis. Nat Commun 2023; 14:4816. [PMID: 37558666 PMCID: PMC10412576 DOI: 10.1038/s41467-023-40541-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 07/30/2023] [Indexed: 08/11/2023] Open
Abstract
Cholesterol biosynthesis is a highly regulated, oxygen-dependent pathway, vital for cell membrane integrity and growth. In fungi, the dependency on oxygen for sterol production has resulted in a shared transcriptional response, resembling prolyl hydroxylation of Hypoxia Inducible Factors (HIFs) in metazoans. Whether an analogous metazoan pathway exists is unknown. Here, we identify Sterol Regulatory Element Binding Protein 2 (SREBP2), the key transcription factor driving sterol production in mammals, as an oxygen-sensitive regulator of cholesterol synthesis. SREBP2 degradation in hypoxia overrides the normal sterol-sensing response, and is HIF independent. We identify MARCHF6, through its NADPH-mediated activation in hypoxia, as the main ubiquitin ligase controlling SREBP2 stability. Hypoxia-mediated degradation of SREBP2 protects cells from statin-induced cell death by forcing cells to rely on exogenous cholesterol uptake, explaining why many solid organ tumours become auxotrophic for cholesterol. Our findings therefore uncover an oxygen-sensitive pathway for governing cholesterol synthesis through regulated SREBP2-dependent protein degradation.
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Affiliation(s)
- Anna S Dickson
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
| | - Tekle Pauzaite
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
| | - Esther Arnaiz
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
- Ochre-Bio Ltd, Hayakawa Building, Oxford Science Park, Edmund Halley Road, Oxford, OX4 4GB, UK
| | - Brian M Ortmann
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
- Biosciences Institute, Newcastle University, Herschel Building, Level 6, Brewery Lane, Newcastle upon Tyne, NE1 7RU, UK
| | - James A West
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
| | - Norbert Volkmar
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
- Institute for Molecular Systems Biology (IMSB), ETH Zürich, Zürich, Switzerland
- DISCO Pharmaceuticals Swiss GmbH, ETH Zürich, Zürich, Switzerland
| | - Anthony W Martinelli
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
| | - Zhaoqi Li
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Tango Therapeutics, 201 Brookline Ave Suite 901, Boston, MA, USA
| | - Niek Wit
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
| | - Dennis Vitkup
- Department of Systems Biology, Columbia University, New York, NY, USA
- Department of Biomedical Informatics, Columbia University, New York, NY, USA
| | - Arthur Kaser
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
| | - Paul J Lehner
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK
| | - James A Nathan
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge, CB2 0AW, UK.
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10
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Mun SH, Lee CS, Kim HJ, Kim J, Lee H, Yang J, Im SH, Kim JH, Seong JK, Hwang CS. Marchf6 E3 ubiquitin ligase critically regulates endoplasmic reticulum stress, ferroptosis, and metabolic homeostasis in POMC neurons. Cell Rep 2023; 42:112746. [PMID: 37421621 DOI: 10.1016/j.celrep.2023.112746] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/18/2023] [Accepted: 06/19/2023] [Indexed: 07/10/2023] Open
Abstract
The metabolic prohormone pro-opiomelanocortin (POMC) is generally translocated into the endoplasmic reticulum (ER) for entry into the secretory pathway. Patients with mutations within the signal peptide (SP) of POMC or its adjoining segment develop metabolic disorders. However, the existence, metabolic fate, and functional outcomes of cytosol-retained POMC remain unclear. Here, we show that SP-uncleaved POMC is produced in the cytosol of POMC neuronal cells, thus inducing ER stress and ferroptotic cell death. Mechanistically, the cytosol-retained POMC sequesters the chaperone Hspa5 and subsequently accelerates degradation of the glutathione peroxidase Gpx4, a core regulator of ferroptosis, via the chaperone-mediated autophagy. We also show that the Marchf6 E3 ubiquitin ligase mediates the degradation of cytosol-retained POMC, thereby preventing ER stress and ferroptosis. Furthermore, POMC-Cre-mediated Marchf6-deficient mice exhibit hyperphagia, reduced energy expenditure, and weight gain. These findings suggest that Marchf6 is a critical regulator of ER stress, ferroptosis, and metabolic homeostasis in POMC neurons.
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Affiliation(s)
- Sang-Hyeon Mun
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Chang-Seok Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Hyun Jin Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Jiye Kim
- Korea Mouse Phenotyping Center, Seoul National University, Seoul 08826, South Korea; Laboratory of Developmental Biology and Genomics, Research Institute for Veterinary Science, and BK21 PLUS Program for Creative Veterinary Science Research, College of Veterinary Medicine, Seoul National University, Seoul 08826, South Korea; Interdisciplinary Program for Bioinformatics, Program for Cancer Biology and BIO-MAX/N-Bio Institute, Seoul National University, Seoul 08826, South Korea
| | - Haena Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Jihye Yang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Sin-Hyeog Im
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea; Institute of Convergence Science, Yonsei University, Seoul 03722, South Korea; ImmunoBiome, Inc, Pohang 37666, Republic of Korea
| | - Joung-Hun Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea; Institute of Convergence Science, Yonsei University, Seoul 03722, South Korea
| | - Je Kyung Seong
- Korea Mouse Phenotyping Center, Seoul National University, Seoul 08826, South Korea; Laboratory of Developmental Biology and Genomics, Research Institute for Veterinary Science, and BK21 PLUS Program for Creative Veterinary Science Research, College of Veterinary Medicine, Seoul National University, Seoul 08826, South Korea; Interdisciplinary Program for Bioinformatics, Program for Cancer Biology and BIO-MAX/N-Bio Institute, Seoul National University, Seoul 08826, South Korea
| | - Cheol-Sang Hwang
- Department of Life Sciences, Korea University, Seoul 02841, South Korea.
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11
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Farrawell NE, Bax M, McAlary L, McKenna J, Maksour S, Do-Ha D, Rayner SL, Blair IP, Chung RS, Yerbury JJ, Ooi L, Saunders DN. ALS-linked CCNF variant disrupts motor neuron ubiquitin homeostasis. Hum Mol Genet 2023; 32:2386-2398. [PMID: 37220877 PMCID: PMC10652331 DOI: 10.1093/hmg/ddad063] [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: 09/28/2022] [Revised: 03/22/2023] [Accepted: 04/12/2023] [Indexed: 05/25/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are fatal neurodegenerative disorders that share pathological features, including the aberrant accumulation of ubiquitinated protein inclusions within motor neurons. Previously, we have shown that the sequestration of ubiquitin (Ub) into inclusions disrupts Ub homeostasis in cells expressing ALS-associated variants superoxide dismutase 1 (SOD1), fused in sarcoma (FUS) and TAR DNA-binding protein 43 (TDP-43). Here, we investigated whether an ALS/FTD-linked pathogenic variant in the CCNF gene, encoding the E3 Ub ligase Cyclin F (CCNF), also perturbs Ub homeostasis. The presence of a pathogenic CCNF variant was shown to cause ubiquitin-proteasome system (UPS) dysfunction in induced pluripotent stem cell-derived motor neurons harboring the CCNF S621G mutation. The expression of the CCNFS621G variant was associated with an increased abundance of ubiquitinated proteins and significant changes in the ubiquitination of key UPS components. To further investigate the mechanisms responsible for this UPS dysfunction, we overexpressed CCNF in NSC-34 cells and found that the overexpression of both wild-type (WT) and the pathogenic variant of CCNF (CCNFS621G) altered free Ub levels. Furthermore, double mutants designed to decrease the ability of CCNF to form an active E3 Ub ligase complex significantly improved UPS function in cells expressing both CCNFWT and the CCNFS621G variant and were associated with increased levels of free monomeric Ub. Collectively, these results suggest that alterations to the ligase activity of the CCNF complex and the subsequent disruption to Ub homeostasis play an important role in the pathogenesis of CCNF-associated ALS/FTD.
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Affiliation(s)
- Natalie E Farrawell
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Monique Bax
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Luke McAlary
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Jessie McKenna
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Simon Maksour
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Dzung Do-Ha
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Stephanie L Rayner
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney 2109, New South Wales, Australia
| | - Ian P Blair
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney 2109, New South Wales, Australia
| | - Roger S Chung
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney 2109, New South Wales, Australia
| | - Justin J Yerbury
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Lezanne Ooi
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Darren N Saunders
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- School of Medical Sciences, University of Sydney, Sydney 2006, Australia
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12
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Badawi S, Mohamed FE, Varghese DS, Ali BR. Genetic disruption of mammalian endoplasmic reticulum-associated protein degradation: Human phenotypes and animal and cellular disease models. Traffic 2023. [PMID: 37188482 DOI: 10.1111/tra.12902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/28/2023] [Accepted: 05/02/2023] [Indexed: 05/17/2023]
Abstract
Endoplasmic reticulum-associated protein degradation (ERAD) is a stringent quality control mechanism through which misfolded, unassembled and some native proteins are targeted for degradation to maintain appropriate cellular and organelle homeostasis. Several in vitro and in vivo ERAD-related studies have provided mechanistic insights into ERAD pathway activation and its consequent events; however, a majority of these have investigated the effect of ERAD substrates and their consequent diseases affecting the degradation process. In this review, we present all reported human single-gene disorders caused by genetic variation in genes that encode ERAD components rather than their substrates. Additionally, after extensive literature survey, we present various genetically manipulated higher cellular and mammalian animal models that lack specific components involved in various stages of the ERAD pathway.
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Affiliation(s)
- Sally Badawi
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Feda E Mohamed
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Divya Saro Varghese
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Bassam R Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
- ASPIRE Precision Medicine Research Institute Abu Dhabi, United Arab Emirates University, Al Ain, United Arab Emirates
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13
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Paul AA, Szulc NA, Kobiela A, Brown SJ, Pokrzywa W, Gutowska-Owsiak D. In silico analysis of the profilaggrin sequence indicates alterations in the stability, degradation route, and intracellular protein fate in filaggrin null mutation carriers. Front Mol Biosci 2023; 10:1105678. [PMID: 37200867 PMCID: PMC10185843 DOI: 10.3389/fmolb.2023.1105678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 04/19/2023] [Indexed: 05/20/2023] Open
Abstract
Background: Loss of function mutation in FLG is the major genetic risk factor for atopic dermatitis (AD) and other allergic manifestations. Presently, little is known about the cellular turnover and stability of profilaggrin, the protein encoded by FLG. Since ubiquitination directly regulates the cellular fate of numerous proteins, their degradation and trafficking, this process could influence the concentration of filaggrin in the skin. Objective: To determine the elements mediating the interaction of profilaggrin with the ubiquitin-proteasome system (i.e., degron motifs and ubiquitination sites), the features responsible for its stability, and the effect of nonsense and frameshift mutations on profilaggrin turnover. Methods: The effect of inhibition of proteasome and deubiquitinases on the level and modifications of profilaggrin and processed products was assessed by immunoblotting. Wild-type profilaggrin sequence and its mutated variants were analysed in silico using the DEGRONOPEDIA and Clustal Omega tool. Results: Inhibition of proteasome and deubiquitinases stabilizes profilaggrin and its high molecular weight of presumably ubiquitinated derivatives. In silico analysis of the sequence determined that profilaggrin contains 18 known degron motifs as well as multiple canonical and non-canonical ubiquitination-prone residues. FLG mutations generate products with increased stability scores, altered usage of the ubiquitination marks, and the frequent appearance of novel degrons, including those promoting C-terminus-mediated degradation routes. Conclusion: The proteasome is involved in the turnover of profilaggrin, which contains multiple degrons and ubiquitination-prone residues. FLG mutations alter those key elements, affecting the degradation routes and the mutated products' stability.
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Affiliation(s)
- Argho Aninda Paul
- Experimental and Translational Immunology Group, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, Gdansk, Poland
| | - Natalia A. Szulc
- Laboratory of Protein Metabolism, International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Adrian Kobiela
- Experimental and Translational Immunology Group, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, Gdansk, Poland
| | - Sara J. Brown
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom
| | - Wojciech Pokrzywa
- Laboratory of Protein Metabolism, International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Danuta Gutowska-Owsiak
- Experimental and Translational Immunology Group, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, Gdansk, Poland
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14
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Qian L, Scott NA, Capell-Hattam IM, Draper EA, Fenton NM, Luu W, Sharpe LJ, Brown AJ. Cholesterol synthesis enzyme SC4MOL is fine-tuned by sterols and targeted for degradation by the E3 ligase MARCHF6. J Lipid Res 2023; 64:100362. [PMID: 36958722 PMCID: PMC10176258 DOI: 10.1016/j.jlr.2023.100362] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 02/09/2023] [Accepted: 02/25/2023] [Indexed: 03/25/2023] Open
Abstract
Cholesterol biosynthesis is a highly regulated pathway, with over 20 enzymes controlled at the transcriptional and post-translational level. Whilst some enzymes remain stable, increased sterol levels can trigger degradation of several synthesis enzymes via the ubiquitin-proteasome system. Of note, we previously identified four cholesterol synthesis enzymes as substrates for one E3 ubiquitin ligase, membrane-associated RING-CH-type finger 6 (MARCHF6). Whether MARCHF6 targets the cholesterol synthesis pathway at other points is unknown. In addition, the post-translational regulation of many cholesterol synthesis enzymes, including the C4-demethylation complex (sterol-C4-methyl oxidase-like, SC4MOL; NAD(P) dependent steroid dehydrogenase-like, NSDHL; hydroxysteroid 17-beta dehydrogenase, HSD17B7) is largely uncharacterized. Using cultured mammalian cell-lines (human-derived and Chinese Hamster Ovary cells), we show SC4MOL, the first acting enzyme of C4-demethylation, is a MARCHF6 substrate, and is rapidly turned over and sensitive to sterols. Sterol depletion stabilizes SC4MOL protein levels, whilst sterol excess downregulates both transcript and protein levels. Furthermore, we found SC4MOL depletion by siRNA results in a significant decrease in total cell cholesterol. Thus, our work indicates SC4MOL is the most regulated enzyme in the C4-demethylation complex. Our results further implicate MARCHF6 as a crucial post-translational regulator of cholesterol synthesis, with this E3 ubiquitin ligase controlling levels of at least five enzymes of the pathway.
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Affiliation(s)
- Lydia Qian
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Nicola A Scott
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Isabelle M Capell-Hattam
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Eliza A Draper
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Nicole M Fenton
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Winnie Luu
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Laura J Sharpe
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales 2052, Australia.
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15
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McKenna MJ, Shao S. The Endoplasmic Reticulum and the Fidelity of Nascent Protein Localization. Cold Spring Harb Perspect Biol 2023; 15:a041249. [PMID: 36041782 PMCID: PMC9979852 DOI: 10.1101/cshperspect.a041249] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
High-fidelity protein localization is essential to define the identities and functions of different organelles and to maintain cellular homeostasis. Accurate localization of nascent proteins requires specific protein targeting pathways as well as quality control (QC) mechanisms to remove mislocalized proteins. The endoplasmic reticulum (ER) is the first destination for approximately one-third of the eukaryotic proteome and a major site of protein biosynthesis and QC. In mammalian cells, trafficking from the ER provides nascent proteins access to the extracellular space and essentially every cellular membrane and organelle except for mitochondria and possibly peroxisomes. Here, we discuss the biosynthetic mechanisms that deliver nascent proteins to the ER and the QC mechanisms that interface with the ER to correct or degrade mislocalized proteins.
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Affiliation(s)
- Michael J McKenna
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts 02115, USA
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts 02115, USA
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16
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Wang W, Lu J, Yang WC, Spear ED, Michaelis S, Matunis MJ. Analysis of a degron-containing reporter protein GFP-CL1 reveals a role for SUMO1 in cytosolic protein quality control. J Biol Chem 2023; 299:102851. [PMID: 36587767 PMCID: PMC9898758 DOI: 10.1016/j.jbc.2022.102851] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/30/2022] Open
Abstract
Misfolded proteins are recognized and degraded through protein quality control (PQC) pathways, which are essential for maintaining proteostasis and normal cellular functions. Defects in PQC can result in disease, including cancer, cardiovascular disease, and neurodegeneration. The small ubiquitin-related modifiers (SUMOs) were previously implicated in the degradation of nuclear misfolded proteins, but their functions in cytoplasmic PQC are unclear. Here, in a systematic screen of SUMO protein mutations in the budding yeast Saccharomyces cerevisiae, we identified a mutant allele (Smt3-K38A/K40A) that sensitizes cells to proteotoxic stress induced by amino acid analogs. Smt3-K38A/K40A mutant strains also exhibited a defect in the turnover of a soluble PQC model substrate containing the CL1 degron (NES-GFP-Ura3-CL1) localized in the cytoplasm, but not the nucleus. Using human U2OS SUMO1- and SUMO2-KO cell lines, we observed a similar SUMO-dependent pathway for degradation of the mammalian degron-containing PQC reporter protein, GFP-CL1, also only in the cytoplasm but not the nucleus. Moreover, we found that turnover of GFP-CL1 in the cytoplasm was uniquely dependent on SUMO1 but not the SUMO2 paralogue. Additionally, we showed that turnover of GFP-CL1 in the cytoplasm is dependent on the AAA-ATPase, Cdc48/p97. Cellular fractionation studies and analysis of a SUMO1-GFP-CL1 fusion protein revealed that SUMO1 promotes cytoplasmic misfolded protein degradation by maintaining substrate solubility. Collectively, our findings reveal a conserved and previously unrecognized role for SUMO1 in regulating cytoplasmic PQC and provide valuable insights into the roles of sumoylation in PQC-associated diseases.
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Affiliation(s)
- Wei Wang
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jian Lu
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Wei-Chih Yang
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Eric D Spear
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Susan Michaelis
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Michael J Matunis
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA.
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17
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Depienne C, van den Maagdenberg AMJM, Kühnel T, Ishiura H, Corbett MA, Tsuji S. Insights into familial adult myoclonus epilepsy pathogenesis: How the same repeat expansion in six unrelated genes may lead to cortical excitability. Epilepsia 2023. [PMID: 36622139 DOI: 10.1111/epi.17504] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 12/22/2022] [Accepted: 01/06/2023] [Indexed: 01/10/2023]
Abstract
Familial adult myoclonus epilepsy (FAME) results from the same pathogenic TTTTA/TTTCA pentanucleotide repeat expansion in six distinct genes encoding proteins with different subcellular localizations and very different functions, which poses the issue of what causes the neurobiological disturbances that lead to the clinical phenotype. Postmortem and electrophysiological studies have pointed to cortical hyperexcitability as well as dysfunction and neurodegeneration of both the cortex and cerebellum of FAME subjects. FAME expansions, contrary to the same expansion in DAB1 causing spinocerebellar ataxia type 37, seem to have no or limited impact on their recipient gene expression, which suggests a pathophysiological mechanism independent of the gene and its function. Current hypotheses include toxicity of the RNA molecules carrying UUUCA repeats, or toxicity of polypeptides encoded by the repeats, a mechanism known as repeat-associated non-AUG translation. The analysis of postmortem brains of FAME1 expansion (in SAMD12) carriers has revealed the presence of RNA foci that could be formed by the aggregation of RNA molecules with abnormal UUUCA repeats, but evidence is still lacking for other FAME subtypes. Even when the expansion is located in a gene ubiquitously expressed, expression of repeats remains undetectable in peripheral tissues (blood, skin). Therefore, the development of appropriate cellular models (induced pluripotent stem cell-derived neurons) or the study of affected tissues in patients is required to elucidate how FAME repeat expansions located in unrelated genes lead to disease.
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Affiliation(s)
- Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Arn M J M van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.,Department of Neurology, Leiden University Medical Center, Leiden, the Netherlands
| | - Theresa Kühnel
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Hiroyuki Ishiura
- Department of Neurology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.,Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Mark A Corbett
- Robinson Research Institute, University of Adelaide, Adelaide Medical School, Adelaide, South Australia, Australia
| | - Shoji Tsuji
- Department of Neurology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.,Institute of Medical Genomics, International University of Health and Welfare, Chiba, Japan
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18
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Shedding of N-acetylglucosaminyltransferase-V is regulated by maturity of cellular N-glycan. Commun Biol 2022; 5:743. [PMID: 35915223 PMCID: PMC9343384 DOI: 10.1038/s42003-022-03697-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 07/11/2022] [Indexed: 11/18/2022] Open
Abstract
The number of N-glycan branches on glycoproteins is closely related to the development and aggravation of various diseases. Dysregulated formation of the branch produced by N-acetylglucosaminyltransferase-V (GnT-V, also called as MGAT5) promotes cancer growth and malignancy. However, it is largely unknown how the activity of GnT-V in cells is regulated. Here, we discover that the activity of GnT-V in cells is selectively upregulated by changing cellular N-glycans from mature to immature forms. Our glycomic analysis further shows that loss of terminal modifications of N-glycans resulted in an increase in the amount of the GnT-V-produced branch. Mechanistically, shedding (cleavage and extracellular secretion) of GnT-V mediated by signal peptide peptidase-like 3 (SPPL3) protease is greatly inhibited by blocking maturation of cellular N-glycans, resulting in an increased level of GnT-V protein in cells. Alteration of cellular N-glycans hardly impairs expression or localization of SPPL3; instead, SPPL3-mediated shedding of GnT-V is shown to be regulated by N-glycans on GnT-V, suggesting that the level of GnT-V cleavage is regulated by its own N-glycan structures. These findings shed light on a mechanism of secretion-based regulation of GnT-V activity. Cleavage of the glycan-branching enzyme N-acetylglucosaminyltransferase-V (GnT-V) by signal peptide peptidase-like 3 (SPPL3) protease and extracellular secretion of active glycan GnT-V depend on GnT-V’s own glycosylation state.
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19
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McKenna MJ, Adams BM, Chu V, Paulo JA, Shao S. ATP13A1 prevents ERAD of folding-competent mislocalized and misoriented proteins. Mol Cell 2022; 82:4277-4289.e10. [PMID: 36283413 PMCID: PMC9675726 DOI: 10.1016/j.molcel.2022.09.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 08/18/2022] [Accepted: 09/26/2022] [Indexed: 11/18/2022]
Abstract
The biosynthesis of thousands of proteins requires targeting a signal sequence or transmembrane segment (TM) to the endoplasmic reticulum (ER). These hydrophobic ɑ helices must localize to the appropriate cellular membrane and integrate in the correct topology to maintain a high-fidelity proteome. Here, we show that the P5A-ATPase ATP13A1 prevents the accumulation of mislocalized and misoriented proteins, which are eliminated by different ER-associated degradation (ERAD) pathways in mammalian cells. Without ATP13A1, mitochondrial tail-anchored proteins mislocalize to the ER through the ER membrane protein complex and are cleaved by signal peptide peptidase for ERAD. ATP13A1 also facilitates the topogenesis of a subset of proteins with an N-terminal TM or signal sequence that should insert into the ER membrane with a cytosolic N terminus. Without ATP13A1, such proteins accumulate in the wrong orientation and are targeted for ERAD by distinct ubiquitin ligases. Thus, ATP13A1 prevents ERAD of diverse proteins capable of proper folding.
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Affiliation(s)
- Michael J McKenna
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Benjamin M Adams
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Vincent Chu
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA.
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20
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The MARCHF6 E3 ubiquitin ligase acts as an NADPH sensor for the regulation of ferroptosis. Nat Cell Biol 2022; 24:1239-1251. [PMID: 35941365 DOI: 10.1038/s41556-022-00973-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 06/29/2022] [Indexed: 01/16/2023]
Abstract
Ferroptosis is a unique form of cell death caused by excessive iron-dependent lipid peroxidation. The level of the anabolic reductant NADPH is a biomarker of ferroptosis sensitivity. However, specific regulators that detect cellular NADPH levels, thereby modulating downstream ferroptosis cascades, are largely unknown. We show here that the transmembrane endoplasmic reticulum MARCHF6 E3 ubiquitin ligase recognizes NADPH through its C-terminal regulatory region. This interaction upregulates the E3 ligase activity of MARCHF6, thus downregulating ferroptosis. We also found that MARCHF6 mediates the degradation of the key ferroptosis effectors ACSL4 and p53. Furthermore, inhibiting ferroptosis rescued the growth of MARCHF6-deficient tumours and peri-natal lethality of Marchf6-/- mice. Together, these findings identify MARCHF6 as a previously unknown NADPH sensor in the ubiquitin system and a crucial regulator of ferroptosis.
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21
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Hill J, Nyathi Y. USP5 enhances SGTA mediated protein quality control. PLoS One 2022; 17:e0257786. [PMID: 35895711 PMCID: PMC9328565 DOI: 10.1371/journal.pone.0257786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 07/11/2022] [Indexed: 11/18/2022] Open
Abstract
Mislocalised membrane proteins (MLPs) present a risk to the cell due to exposed hydrophobic amino acids which cause MLPs to aggregate. Previous studies identified SGTA as a key component of the machinery that regulates the quality control of MLPs. Overexpression of SGTA promotes deubiqutination of MLPs resulting in their accumulation in cytosolic inclusions, suggesting SGTA acts in collaboration with deubiquitinating enzymes (DUBs) to exert these effects. However, the DUBs that play a role in this process have not been identified. In this study we have identified the ubiquitin specific peptidase 5 (USP5) as a DUB important in regulating the quality control of MLPs. We show that USP5 is in complex with SGTA, and this association is increased in the presence of an MLP. Overexpression of SGTA results in an increase in steady-state levels of MLPs suggesting a delay in proteasomal degradation of substrates. However, our results show that this effect is strongly dependent on the presence of USP5. We find that in the absence of USP5, the ability of SGTA to increase the steady state levels of MLPs is compromised. Moreover, knockdown of USP5 results in a reduction in the steady state levels of MLPs, while overexpression of USP5 increases the steady state levels. Our findings suggest that the interaction of SGTA with USP5 enables specific MLPs to escape proteasomal degradation allowing selective modulation of MLP quality control. These findings progress our understanding of aggregate formation, a hallmark in a range of neurodegenerative diseases and type II diabetes, as well as physiological processes of aggregate clearance.
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Affiliation(s)
- Jake Hill
- School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Lincoln, United Kingdom
- School of Chemistry and Bioscience, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom
| | - Yvonne Nyathi
- School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Lincoln, United Kingdom
- School of Chemistry and Bioscience, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom
- * E-mail:
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22
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Christianson JC, Carvalho P. Order through destruction: how ER-associated protein degradation contributes to organelle homeostasis. EMBO J 2022; 41:e109845. [PMID: 35170763 PMCID: PMC8922271 DOI: 10.15252/embj.2021109845] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 01/09/2022] [Accepted: 01/25/2022] [Indexed: 12/24/2022] Open
Abstract
The endoplasmic reticulum (ER) is a large, dynamic, and multifunctional organelle. ER protein homeostasis is essential for the coordination of its diverse functions and depends on ER-associated protein degradation (ERAD). The latter process selects target proteins in the lumen and membrane of the ER, promotes their ubiquitination, and facilitates their delivery into the cytosol for degradation by the proteasome. Originally characterized for a role in the degradation of misfolded proteins and rate-limiting enzymes of sterol biosynthesis, the many branches of ERAD now appear to control the levels of a wider range of substrates and influence more broadly the organization and functions of the ER, as well as its interactions with adjacent organelles. Here, we discuss recent mechanistic advances in our understanding of ERAD and of its consequences for the regulation of ER functions.
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Affiliation(s)
- John C Christianson
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal SciencesBotnar Research CentreUniversity of OxfordOxfordUK
| | - Pedro Carvalho
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
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23
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Hegde RS, Keenan RJ. The mechanisms of integral membrane protein biogenesis. Nat Rev Mol Cell Biol 2022; 23:107-124. [PMID: 34556847 DOI: 10.1038/s41580-021-00413-2] [Citation(s) in RCA: 83] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2021] [Indexed: 02/08/2023]
Abstract
Roughly one quarter of all genes code for integral membrane proteins that are inserted into the plasma membrane of prokaryotes or the endoplasmic reticulum membrane of eukaryotes. Multiple pathways are used for the targeting and insertion of membrane proteins on the basis of their topological and biophysical characteristics. Multipass membrane proteins span the membrane multiple times and face the additional challenges of intramembrane folding. In many cases, integral membrane proteins require assembly with other proteins to form multi-subunit membrane protein complexes. Recent biochemical and structural analyses have provided considerable clarity regarding the molecular basis of membrane protein targeting and insertion, with tantalizing new insights into the poorly understood processes of multipass membrane protein biogenesis and multi-subunit protein complex assembly.
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Affiliation(s)
- Ramanujan S Hegde
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Robert J Keenan
- Gordon Center for Integrative Science, The University of Chicago, Chicago, IL, USA.
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24
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Peters L, Depienne C, Klebe S. Familial adult myoclonic epilepsy (FAME): clinical features, molecular characteristics, pathophysiological aspects and diagnostic work-up. MED GENET-BERLIN 2021; 33:311-318. [PMID: 38835431 PMCID: PMC11006339 DOI: 10.1515/medgen-2021-2100] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 11/16/2021] [Indexed: 06/06/2024]
Abstract
Familial adult myoclonic epilepsy (FAME) is a rare autosomal dominant disorder characterized by myoclonus and seizures. The genetic variant underlying FAME is an intronic repeat expansion composed of two different pentamers: an expanded TTTTA, which is the motif originally present at the locus, and an insertion of TTTCA repeats, which is usually located at the 3' end and likely corresponds to the pathogenic part of the expansion. This repeat expansion has been identified so far in six genes located on different chromosomes, which remarkably encode proteins with distinct cellular localizations and functions. Although the exact pathophysiological mechanisms remain to be clarified, it is likely that FAME repeat expansions lead to disease independently of the gene where they occur. We herein review the clinical and molecular characteristics of this singular genetic disorder, which interestingly shares clinical features with other more common neurological disorders whose etiology remains mainly unsolved.
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Affiliation(s)
- Lorenz Peters
- Department of Neurology, University Hospital Essen, Essen, Germany
| | - Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Stephan Klebe
- Department of Neurology, University Hospital Essen, Essen, Germany
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25
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Smith CE, Tsai YC, Liang YH, Khago D, Mariano J, Li J, Tarasov SG, Gergel E, Tsai B, Villaneuva M, Clapp ME, Magidson V, Chari R, Byrd RA, Ji X, Weissman AM. A structurally conserved site in AUP1 binds the E2 enzyme UBE2G2 and is essential for ER-associated degradation. PLoS Biol 2021; 19:e3001474. [PMID: 34879065 PMCID: PMC8699718 DOI: 10.1371/journal.pbio.3001474] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 12/23/2021] [Accepted: 11/05/2021] [Indexed: 12/22/2022] Open
Abstract
Endoplasmic reticulum-associated degradation (ERAD) is a protein quality control pathway of fundamental importance to cellular homeostasis. Although multiple ERAD pathways exist for targeting topologically distinct substrates, all pathways require substrate ubiquitination. Here, we characterize a key role for the UBE2G2 Binding Region (G2BR) of the ERAD accessory protein ancient ubiquitous protein 1 (AUP1) in ERAD pathways. This 27-amino acid (aa) region of AUP1 binds with high specificity and low nanomolar affinity to the backside of the ERAD ubiquitin-conjugating enzyme (E2) UBE2G2. The structure of the AUP1 G2BR (G2BRAUP1) in complex with UBE2G2 reveals an interface that includes a network of salt bridges, hydrogen bonds, and hydrophobic interactions essential for AUP1 function in cells. The G2BRAUP1 shares significant structural conservation with the G2BR found in the E3 ubiquitin ligase gp78 and in vitro can similarly allosterically activate ubiquitination in conjunction with ERAD E3s. In cells, AUP1 is uniquely required to maintain normal levels of UBE2G2; this is due to G2BRAUP1 binding to the E2 and preventing its rapid degradation. In addition, the G2BRAUP1 is required for both ER membrane recruitment of UBE2G2 and for its activation at the ER membrane. Thus, by binding to the backside of a critical ERAD E2, G2BRAUP1 plays multiple critical roles in ERAD.
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Affiliation(s)
- Christopher E. Smith
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Yien Che Tsai
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Yu-He Liang
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Domarin Khago
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Jennifer Mariano
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Jess Li
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Sergey G. Tarasov
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Emma Gergel
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Borong Tsai
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Matthew Villaneuva
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Michelle E. Clapp
- Genome Modification Core, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Valentin Magidson
- Optical Microscopy and Analysis Laboratory, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Raj Chari
- Genome Modification Core, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - R. Andrew Byrd
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Xinhua Ji
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Allan M. Weissman
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
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26
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Kawaguchi K, Yamamoto-Hino M, Murakami Y, Kinoshita T, Goto S. Hrd1-dependent Degradation of the Unassembled PIGK Subunit of the GPI Transamidase Complex. Cell Struct Funct 2021; 46:65-71. [PMID: 34193731 PMCID: PMC10511060 DOI: 10.1247/csf.21019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 06/08/2021] [Indexed: 11/11/2022] Open
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins are post-transcriptionally modified with GPI and anchored to the plasma membrane. GPI is attached to nascent proteins in the endoplasmic reticulum by the GPI transamidase complex, which consists of PIGT, PIGK, GPAA1, PIGU, and PIGS. Of these, PIGK is a catalytic subunit that is unstable without PIGT. This study investigated the pathway by which unassembled PIGK not incorporated into the complex is degraded. We showed that unassembled PIGK was degraded via the proteasome-dependent pathway and that Hrd1 (also known as SYVN1), a ubiquitin ligase involved in the endoplasmic reticulum-associated degradation pathway, was responsible for degradation of unassembled PIGK.Key words: Glycosylphosphatidylinositol, GPI transamidase complex, protein stability, transamidation, ERAD.
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Affiliation(s)
- Kohei Kawaguchi
- Department of Life Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Miki Yamamoto-Hino
- Department of Life Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Yoshiko Murakami
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Taroh Kinoshita
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Satoshi Goto
- Department of Life Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
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27
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Abstract
Lipid droplets (LDs) are endoplasmic reticulum-derived organelles that consist of a core of neutral lipids encircled by a phospholipid monolayer decorated with proteins. As hubs of cellular lipid and energy metabolism, LDs are inherently involved in the etiology of prevalent metabolic diseases such as obesity and nonalcoholic fatty liver disease. The functions of LDs are regulated by a unique set of associated proteins, the LD proteome, which includes integral membrane and peripheral proteins. These proteins control key activities of LDs such as triacylglycerol synthesis and breakdown, nutrient sensing and signal integration, and interactions with other organelles. Here we review the mechanisms that regulate the composition of the LD proteome, such as pathways that mediate selective and bulk LD protein degradation and potential connections between LDs and cellular protein quality control.
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Affiliation(s)
- Melissa A Roberts
- Department of Molecular and Cell Biology and Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720, USA;
| | - James A Olzmann
- Department of Molecular and Cell Biology and Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720, USA; .,Chan Zuckerberg Biohub, San Francisco, California 94158, USA
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28
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Fenech EJ, Ben-Dor S, Schuldiner M. Double the Fun, Double the Trouble: Paralogs and Homologs Functioning in the Endoplasmic Reticulum. Annu Rev Biochem 2021; 89:637-666. [PMID: 32569522 DOI: 10.1146/annurev-biochem-011520-104831] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The evolution of eukaryotic genomes has been propelled by a series of gene duplication events, leading to an expansion in new functions and pathways. While duplicate genes may retain some functional redundancy, it is clear that to survive selection they cannot simply serve as a backup but rather must acquire distinct functions required for cellular processes to work accurately and efficiently. Understanding these differences and characterizing gene-specific functions is complex. Here we explore different gene pairs and families within the context of the endoplasmic reticulum (ER), the main cellular hub of lipid biosynthesis and the entry site for the secretory pathway. Focusing on each of the ER functions, we highlight specificities of related proteins and the capabilities conferred to cells through their conservation. More generally, these examples suggest why related genes have been maintained by evolutionary forces and provide a conceptual framework to experimentally determine why they have survived selection.
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Affiliation(s)
- Emma J Fenech
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel;
| | - Shifra Ben-Dor
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel;
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29
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Hickey CM, Breckel C, Zhang M, Theune WC, Hochstrasser M. Protein quality control degron-containing substrates are differentially targeted in the cytoplasm and nucleus by ubiquitin ligases. Genetics 2021; 217:1-19. [PMID: 33683364 PMCID: PMC8045714 DOI: 10.1093/genetics/iyaa031] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 12/07/2020] [Indexed: 12/21/2022] Open
Abstract
Intracellular proteolysis by the ubiquitin-proteasome system regulates numerous processes and contributes to protein quality control (PQC) in all eukaryotes. Covalent attachment of ubiquitin to other proteins is specified by the many ubiquitin ligases (E3s) expressed in cells. Here we determine the E3s in Saccharomyces cerevisiae that function in degradation of proteins bearing various PQC degradation signals (degrons). The E3 Ubr1 can function redundantly with several E3s, including nuclear-localized San1, endoplasmic reticulum/nuclear membrane-embedded Doa10, and chromatin-associated Slx5/Slx8. Notably, multiple degrons are targeted by more ubiquitylation pathways if directed to the nucleus. Degrons initially assigned as exclusive substrates of Doa10 were targeted by Doa10, San1, and Ubr1 when directed to the nucleus. By contrast, very short hydrophobic degrons-typical targets of San1-are shown here to be targeted by Ubr1 and/or San1, but not Doa10. Thus, distinct types of PQC substrates are differentially recognized by the ubiquitin system in a compartment-specific manner. In human cells, a representative short hydrophobic degron appended to the C-terminus of GFP-reduced protein levels compared with GFP alone, consistent with a recent study that found numerous natural hydrophobic C-termini of human proteins can act as degrons. We also report results of bioinformatic analyses of potential human C-terminal degrons, which reveal that most peptide substrates of Cullin-RING ligases (CRLs) are of low hydrophobicity, consistent with previous data showing CRLs target degrons with specific sequences. These studies expand our understanding of PQC in yeast and human cells, including the distinct but overlapping PQC E3 substrate specificity of the cytoplasm and nucleus.
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Affiliation(s)
- Christopher M Hickey
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Carolyn Breckel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Mengwen Zhang
- Department of Chemistry, Yale University, New Haven, CT 06511, USA
| | - William C Theune
- Department of Biology and Environmental Science, University of New Haven, West Haven, CT 06516, USA
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA
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30
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The Degron Architecture of Squalene Monooxygenase and How Specific Lipids Calibrate Levels of This Key Cholesterol Synthesis Enzyme. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021. [PMID: 32979157 DOI: 10.1007/5584_2020_583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Cholesterol synthesis is a fundamental process that contributes to cellular cholesterol homeostasis. Cells execute transcriptional and post-translational mechanisms to control the abundance of enzymes of the cholesterol synthesis pathway, consequently affecting cholesterol production. One such highly tuned enzyme is squalene monooxygenase (SM), which catalyzes a rate-limiting step in the pathway. A well-characterized mechanism is the cholesterol-mediated degradation of SM. Notably, lipids (cholesterol, plasmalogens, squalene, and unsaturated fatty acids) can act as cellular signals that either promote or reduce SM degradation. The N-terminal region of SM consists of the shortest known cholesterol-responsive degron, characterized by atypical membrane anchoring structures, namely a re-entrant loop and an amphipathic helix. SM also undergoes non-canonical ubiquitination on serine, a relatively uncommon attachment site for ubiquitination. The structure of the catalytic domain of SM has been solved, providing insights into the catalytic mechanisms and modes of inhibition by well-known SM inhibitors, some of which have been effective in lowering cholesterol levels in animal models. Certain human cancers have been linked to dysregulation of SM levels and activity, further emphasizing the relevance of SM in health and disease.
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31
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Spitz C, Schlosser C, Guschtschin-Schmidt N, Stelzer W, Menig S, Götz A, Haug-Kröper M, Scharnagl C, Langosch D, Muhle-Goll C, Fluhrer R. Non-canonical Shedding of TNFα by SPPL2a Is Determined by the Conformational Flexibility of Its Transmembrane Helix. iScience 2020; 23:101775. [PMID: 33294784 PMCID: PMC7689174 DOI: 10.1016/j.isci.2020.101775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/21/2020] [Accepted: 11/03/2020] [Indexed: 12/22/2022] Open
Abstract
Ectodomain (EC) shedding defines the proteolytic removal of a membrane protein EC and acts as an important molecular switch in signaling and other cellular processes. Using tumor necrosis factor (TNF)α as a model substrate, we identify a non-canonical shedding activity of SPPL2a, an intramembrane cleaving aspartyl protease of the GxGD type. Proline insertions in the TNFα transmembrane (TM) helix strongly increased SPPL2a non-canonical shedding, while leucine mutations decreased this cleavage. Using biophysical and structural analysis, as well as molecular dynamic simulations, we identified a flexible region in the center of the TNFα wildtype TM domain, which plays an important role in the processing of TNFα by SPPL2a. This study combines molecular biology, biochemistry, and biophysics to provide insights into the dynamic architecture of a substrate's TM helix and its impact on non-canonical shedding. Thus, these data will provide the basis to identify further physiological substrates of non-canonical shedding in the future.
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Affiliation(s)
- Charlotte Spitz
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Christine Schlosser
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Nadja Guschtschin-Schmidt
- Karlsruhe Institute of Technology, Institute for Biological Interfaces 4, 76344 Eggenstein- Leopoldshafen, Germany and Karlsruhe Institute of Technology, Institute of Organic Chemistry, 76131 Karlsruhe, Germany
| | - Walter Stelzer
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Simon Menig
- Physics of Synthetic Biological Systems, Technische Universität München, Maximus-von-Imhof Forum 4, 85340 Freising, Germany
| | - Alexander Götz
- Present Address: Leibniz Supercomputing Centre, Boltzmannstr. 1, 85748 Garching, Germany
| | - Martina Haug-Kröper
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Christina Scharnagl
- Physics of Synthetic Biological Systems, Technische Universität München, Maximus-von-Imhof Forum 4, 85340 Freising, Germany
| | - Dieter Langosch
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Claudia Muhle-Goll
- Karlsruhe Institute of Technology, Institute for Biological Interfaces 4, 76344 Eggenstein- Leopoldshafen, Germany and Karlsruhe Institute of Technology, Institute of Organic Chemistry, 76131 Karlsruhe, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
- DZNE – German Center for Neurodegenerative Diseases, Feodor-Lynen-Str 17, 81377 Munich, Germany
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32
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Ninagawa S, George G, Mori K. Mechanisms of productive folding and endoplasmic reticulum-associated degradation of glycoproteins and non-glycoproteins. Biochim Biophys Acta Gen Subj 2020; 1865:129812. [PMID: 33316349 DOI: 10.1016/j.bbagen.2020.129812] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND The quality of proteins destined for the secretory pathway is ensured by two distinct mechanisms in the endoplasmic reticulum (ER): productive folding of newly synthesized proteins, which is assisted by ER-localized molecular chaperones and in most cases also by disulfide bond formation and transfer of an oligosaccharide unit; and ER-associated degradation (ERAD), in which proteins unfolded or misfolded in the ER are recognized and processed for delivery to the ER membrane complex, retrotranslocated through the complex with simultaneous ubiquitination, extracted by AAA-ATPase to the cytosol, and finally degraded by the proteasome. SCOPE OF REVIEW We describe the mechanisms of productive folding and ERAD, with particular attention to glycoproteins versus non-glycoproteins, and to yeast versus mammalian systems. MAJOR CONCLUSION Molecular mechanisms of the productive folding of glycoproteins and non-glycoproteins mediated by molecular chaperones and protein disulfide isomerases are well conserved from yeast to mammals. Additionally, mammals have gained an oligosaccharide structure-dependent folding cycle for glycoproteins. The molecular mechanisms of ERAD are also well conserved from yeast to mammals, but redundant expression of yeast orthologues in mammals has been encountered, particularly for components involved in recognition and processing of glycoproteins and components of the ER membrane complex involved in retrotranslocation and simultaneous ubiquitination of glycoproteins and non-glycoproteins. This may reflect an evolutionary consequence of increasing quantity or quality needs toward mammals. GENERAL SIGNIFICANCE The introduction of innovative genome editing technology into analysis of the mechanisms of mammalian ERAD, as exemplified here, will provide new insights into the pathogenesis of various diseases.
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Affiliation(s)
- Satoshi Ninagawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
| | - Ginto George
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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33
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Jiang H. Quality control pathways of tail-anchored proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118922. [PMID: 33285177 DOI: 10.1016/j.bbamcr.2020.118922] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/14/2020] [Accepted: 12/01/2020] [Indexed: 12/20/2022]
Abstract
Tail-anchored (TA) proteins have an N-terminal domain in the cytosol and a C-terminal transmembrane domain anchored to a variety of organelle membranes. TA proteins are recognized by targeting factors at the transmembrane domain and C-terminal sequence and are guided to distinct membranes. The promiscuity of targeting sequences and the dysfunction of targeting pathways cause mistargeting of TA proteins. TA proteins are under surveillance by quality control pathways. For resident TA proteins at mitochondrial and ER membranes, intrinsic instability or stimuli induced degrons of the cytosolic and transmembrane domains are sensed by quality control factors to initiate degradation of TA proteins. These pathways are summarized as TA protein degradation-Cytosol (TAD-C) and TAD-Membrane (TAD-M) pathways. For mistargeted and a subset of solitary TA proteins at mitochondrial and peroxisomal membranes, a unique pathway has been revealed in recent years. Msp1/ATAD1 is an AAA-ATPase dually-localized to mitochondrial and peroxisomal membranes. It directly recognizes mistargeted and solitary TA proteins and dislocates them out of membrane. Dislocated substrates are subsequently ubiquitinated by the ER-resident Doa10 ubiquitin E3 ligase complex for degradation. We summarize and discuss the substrate recognition, dislocation and degradation mechanisms of the Msp1 pathway.
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Affiliation(s)
- Hui Jiang
- National Institute of Biological Sciences, Beijing 102206, China; Beijing Key Laboratory of Cell Biology for Animal Aging, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100871, China.
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34
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Scott NA, Sharpe LJ, Brown AJ. The E3 ubiquitin ligase MARCHF6 as a metabolic integrator in cholesterol synthesis and beyond. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1866:158837. [PMID: 33049405 DOI: 10.1016/j.bbalip.2020.158837] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/29/2020] [Accepted: 10/02/2020] [Indexed: 12/19/2022]
Abstract
MARCHF6 is a large multi-pass E3 ubiquitin ligase embedded in the membranes of the endoplasmic reticulum. It participates in endoplasmic reticulum associated degradation, including autoubiquitination, and many of its identified substrates are involved in sterol and lipid metabolism. Post-translationally, MARCHF6 expression is attuned to cholesterol status, with high cholesterol preventing its degradation and hence boosting MARCHF6 levels. By modulating MARCHF6 activity, cholesterol may regulate other aspects of cell metabolism beyond the known repertoire. Whilst we have learnt much about MARCHF6 in the past decade, there are still many more mysteries to be unravelled to fully understand its regulation, substrates, and role in human health and disease.
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Affiliation(s)
- Nicola A Scott
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Laura J Sharpe
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia.
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35
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Signal Peptide Peptidase-Type Proteases: Versatile Regulators with Functions Ranging from Limited Proteolysis to Protein Degradation. J Mol Biol 2020; 432:5063-5078. [DOI: 10.1016/j.jmb.2020.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/02/2020] [Accepted: 05/19/2020] [Indexed: 12/15/2022]
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36
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Mentrup T, Cabrera-Cabrera F, Fluhrer R, Schröder B. Physiological functions of SPP/SPPL intramembrane proteases. Cell Mol Life Sci 2020; 77:2959-2979. [PMID: 32052089 PMCID: PMC7366577 DOI: 10.1007/s00018-020-03470-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/09/2020] [Accepted: 01/22/2020] [Indexed: 01/07/2023]
Abstract
Intramembrane proteolysis describes the cleavage of substrate proteins within their hydrophobic transmembrane segments. Several families of intramembrane proteases have been identified including the aspartyl proteases Signal peptide peptidase (SPP) and its homologues, the SPP-like (SPPL) proteases SPPL2a, SPPL2b, SPPL2c and SPPL3. As presenilin homologues, they employ a similar catalytic mechanism as the well-studied γ-secretase. However, SPP/SPPL proteases cleave transmembrane proteins with a type II topology. The characterisation of SPP/SPPL-deficient mouse models has highlighted a still growing spectrum of biological functions and also promoted the substrate discovery of these proteases. In this review, we will summarise the current hypotheses how phenotypes of these mouse models are linked to the molecular function of the enzymes. At the cellular level, SPP/SPPL-mediated cleavage events rather provide specific regulatory switches than unspecific bulk proteolysis. By this means, a plethora of different cell biological pathways is influenced including signal transduction, membrane trafficking and protein glycosylation.
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Affiliation(s)
- Torben Mentrup
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany
| | - Florencia Cabrera-Cabrera
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Faculty of Medicine, University of Augsburg, Universitätsstraße 2, 86135, Augsburg, Germany
- Biomedizinisches Centrum (BMC), Ludwig Maximilians University of Munich, Feodor-Lynen-Strasse 17, 81377, Munich, Germany
- DZNE-German Center for Neurodegenerative Diseases, Munich, Feodor-Lynen-Strasse 17, 81377, Munich, Germany
| | - Bernd Schröder
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany.
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van de Weijer ML, Krshnan L, Liberatori S, Guerrero EN, Robson-Tull J, Hahn L, Lebbink RJ, Wiertz EJHJ, Fischer R, Ebner D, Carvalho P. Quality Control of ER Membrane Proteins by the RNF185/Membralin Ubiquitin Ligase Complex. Mol Cell 2020; 79:768-781.e7. [PMID: 32738194 PMCID: PMC7482433 DOI: 10.1016/j.molcel.2020.07.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 05/06/2020] [Accepted: 07/07/2020] [Indexed: 12/16/2022]
Abstract
Misfolded proteins in the endoplasmic reticulum (ER) are degraded by ER-associated degradation (ERAD). Although ERAD components involved in degradation of luminal substrates are well characterized, much less is known about quality control of membrane proteins. Here, we analyzed the degradation pathways of two short-lived ER membrane model proteins in mammalian cells. Using a CRISPR-Cas9 genome-wide library screen, we identified an ERAD branch required for quality control of a subset of membrane proteins. Using biochemical and mass spectrometry approaches, we showed that this ERAD branch is defined by an ER membrane complex consisting of the ubiquitin ligase RNF185, the ubiquitin-like domain containing proteins TMUB1/2 and TMEM259/Membralin, a poorly characterized protein. This complex cooperates with cytosolic ubiquitin ligase UBE3C and p97 ATPase in degrading their membrane substrates. Our data reveal that ERAD branches have remarkable specificity for their membrane substrates, suggesting that multiple, perhaps combinatorial, determinants are involved in substrate selection. The RNF185 ubiquitin ligase, Membralin, and TMUB1/2 assemble into an ERAD complex RNF185/Membralin complex targets membrane proteins, including CYP51A1 and TMUB2 RNF185/Membralin and TEB4 ERAD complexes recognize distinct substrate features TEB4 ERAD complex recognizes substrates through their transmembrane domain
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Affiliation(s)
- Michael L van de Weijer
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Logesvaran Krshnan
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Sabrina Liberatori
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Elena Navarro Guerrero
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK
| | - Jacob Robson-Tull
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Lilli Hahn
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Robert Jan Lebbink
- Medical Microbiology, University Medical Center Utrecht, 3584 Utrecht, the Netherlands
| | - Emmanuel J H J Wiertz
- Medical Microbiology, University Medical Center Utrecht, 3584 Utrecht, the Netherlands
| | - Roman Fischer
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK
| | - Daniel Ebner
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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38
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Chua NK, Coates HW, Brown AJ. Squalene monooxygenase: a journey to the heart of cholesterol synthesis. Prog Lipid Res 2020; 79:101033. [DOI: 10.1016/j.plipres.2020.101033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023]
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van den Boomen DJH, Volkmar N, Lehner PJ. Ubiquitin-mediated regulation of sterol homeostasis. Curr Opin Cell Biol 2020; 65:103-111. [PMID: 32580085 DOI: 10.1016/j.ceb.2020.04.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 04/03/2020] [Accepted: 04/26/2020] [Indexed: 11/19/2022]
Abstract
Cholesterol is an essential component of mammalian membranes, and its homeostasis is strictly regulated, with imbalances causing atherosclerosis, Niemann Pick disease, and familial hypercholesterolemia. Cellular cholesterol supply is mediated by LDL-cholesterol import and de novo cholesterol biosynthesis, and both pathways are adjusted to cellular demand by the cholesterol-sensitive SREBP2 transcription factor. Cholesterol homeostasis is modulated by a wide variety of metabolic pathways and the ubiquitination machinery, in particular E3 ubiquitin ligases. In this article, we review recent progress in understanding the role of E3 ubiquitin ligases in the metabolic control of cellular sterol homeostasis.
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Affiliation(s)
- Dick J H van den Boomen
- Cambridge Institute of Therapeutic Immunology & Infectious Disease, University of Cambridge, Cambridge, United Kingdom
| | - Norbert Volkmar
- Cambridge Institute of Therapeutic Immunology & Infectious Disease, University of Cambridge, Cambridge, United Kingdom
| | - Paul J Lehner
- Cambridge Institute of Therapeutic Immunology & Infectious Disease, University of Cambridge, Cambridge, United Kingdom.
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40
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Zhao B, Tsai YC, Jin B, Wang B, Wang Y, Zhou H, Carpenter T, Weissman AM, Yin J. Protein Engineering in the Ubiquitin System: Tools for Discovery and Beyond. Pharmacol Rev 2020; 72:380-413. [PMID: 32107274 PMCID: PMC7047443 DOI: 10.1124/pr.118.015651] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Ubiquitin (UB) transfer cascades consisting of E1, E2, and E3 enzymes constitute a complex network that regulates a myriad of biologic processes by modifying protein substrates. Deubiquitinating enzymes (DUBs) reverse UB modifications or trim UB chains of diverse linkages. Additionally, many cellular proteins carry UB-binding domains (UBDs) that translate the signals encoded in UB chains to target proteins for degradation by proteasomes or in autophagosomes, as well as affect nonproteolytic outcomes such as kinase activation, DNA repair, and transcriptional regulation. Dysregulation of the UB transfer pathways and malfunctions of DUBs and UBDs play causative roles in the development of many diseases. A greater understanding of the mechanism of UB chain assembly and the signals encoded in UB chains should aid in our understanding of disease pathogenesis and guide the development of novel therapeutics. The recent flourish of protein-engineering approaches such as unnatural amino acid incorporation, protein semisynthesis by expressed protein ligation, and high throughput selection by phage and yeast cell surface display has generated designer proteins as powerful tools to interrogate cell signaling mediated by protein ubiquitination. In this study, we highlight recent achievements of protein engineering on mapping, probing, and manipulating UB transfer in the cell. SIGNIFICANCE STATEMENT: The post-translational modification of proteins with ubiquitin alters the fate and function of proteins in diverse ways. Protein engineering is fundamentally transforming research in this area, providing new mechanistic insights and allowing for the exploration of concepts that can potentially be applied to therapeutic intervention.
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Affiliation(s)
- Bo Zhao
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Yien Che Tsai
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Bo Jin
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Bufan Wang
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Yiyang Wang
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Han Zhou
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Tomaya Carpenter
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Allan M Weissman
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
| | - Jun Yin
- Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, and School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China (B.Z., B.J., B.W.); Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China (Y.W.); Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, Maryland (Y.C.T., A.M.W.); and Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia (Y.W., H.Z., T.C., J.Y.)
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Gierisch ME, Giovannucci TA, Dantuma NP. Reporter-Based Screens for the Ubiquitin/Proteasome System. Front Chem 2020; 8:64. [PMID: 32117887 PMCID: PMC7026131 DOI: 10.3389/fchem.2020.00064] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 01/20/2020] [Indexed: 01/14/2023] Open
Abstract
Instant and adequate handling of misfolded or otherwise aberrant proteins is of paramount importance for maintaining protein homeostasis in cells. The ubiquitin/proteasome system (UPS) is a central player in protein quality control as it operates in a seek-and-destroy mode, thereby facilitating elimination of faulty proteins. While proteasome inhibition is in clinical use for the treatment of hematopoietic malignancies, stimulation of the UPS has been proposed as a potential therapeutic strategy for various neurodegenerative disorders. High-throughput screens using genetic approaches or compound libraries are powerful tools to identify therapeutic intervention points and novel drugs. Unlike assays that measure specific activities of components of the UPS, reporter substrates provide us with a more holistic view of the general functional status of the UPS in cells. As such, reporter substrates can reveal new ways to obstruct or stimulate this critical proteolytic pathway. Here, we discuss various reporter substrates for the UPS and their application in the identification of key players and the pursuit for novel therapeutics.
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Affiliation(s)
- Maria E Gierisch
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | | | - Nico P Dantuma
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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43
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Abstract
Endoplasmic reticulum-associated degradation (ERAD) is an essential process that removes misfolded proteins from the ER, preventing cellular dysfunction and disease. While most of the key components of ERAD are known, their specific localization remains a mystery. This study uses in situ cryo-electron tomography to directly visualize the ERAD machinery within the native cellular environment. Proteasomes and Cdc48, the complexes that extract and degrade ER proteins, cluster together in non–membrane-bound cytosolic microcompartments that contact ribosome-free patches on the ER membrane. This discrete molecular organization may facilitate efficient ERAD. Structural analysis reveals that proteasomes directly engage ER-localized substrates, providing evidence for a noncanonical “direct ERAD” pathway. In addition, live-cell fluorescence microscopy suggests that these ER-associated proteasome clusters form by liquid–liquid phase separation. To promote the biochemical reactions of life, cells can compartmentalize molecular interaction partners together within separated non–membrane-bound regions. It is unknown whether this strategy is used to facilitate protein degradation at specific locations within the cell. Leveraging in situ cryo-electron tomography to image the native molecular landscape of the unicellular alga Chlamydomonas reinhardtii, we discovered that the cytosolic protein degradation machinery is concentrated within ∼200-nm foci that contact specialized patches of endoplasmic reticulum (ER) membrane away from the ER–Golgi interface. These non–membrane-bound microcompartments exclude ribosomes and consist of a core of densely clustered 26S proteasomes surrounded by a loose cloud of Cdc48. Active proteasomes in the microcompartments directly engage with putative substrate at the ER membrane, a function canonically assigned to Cdc48. Live-cell fluorescence microscopy revealed that the proteasome clusters are dynamic, with frequent assembly and fusion events. We propose that the microcompartments perform ER-associated degradation, colocalizing the degradation machinery at specific ER hot spots to enable efficient protein quality control.
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Hegde RS, Zavodszky E. Recognition and Degradation of Mislocalized Proteins in Health and Disease. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a033902. [PMID: 30833453 DOI: 10.1101/cshperspect.a033902] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A defining feature of eukaryotic cells is the segregation of complex biochemical processes among different intracellular compartments. The protein targeting, translocation, and trafficking pathways that sustain compartmentalization must recognize a diverse range of clients via degenerate signals. This recognition is imperfect, resulting in polypeptides at incorrect cellular locations. Cells have evolved mechanisms to selectively recognize mislocalized proteins and triage them for degradation or rescue. These spatial quality control pathways maintain cellular protein homeostasis, become especially important during organelle stress, and might contribute to disease when they are impaired or overwhelmed.
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Affiliation(s)
- Ramanujan S Hegde
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Eszter Zavodszky
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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45
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Florian RT, Kraft F, Leitão E, Kaya S, Klebe S, Magnin E, van Rootselaar AF, Buratti J, Kühnel T, Schröder C, Giesselmann S, Tschernoster N, Altmueller J, Lamiral A, Keren B, Nava C, Bouteiller D, Forlani S, Jornea L, Kubica R, Ye T, Plassard D, Jost B, Meyer V, Deleuze JF, Delpu Y, Avarello MDM, Vijfhuizen LS, Rudolf G, Hirsch E, Kroes T, Reif PS, Rosenow F, Ganos C, Vidailhet M, Thivard L, Mathieu A, Bourgeron T, Kurth I, Rafehi H, Steenpass L, Horsthemke B, LeGuern E, Klein KM, Labauge P, Bennett MF, Bahlo M, Gecz J, Corbett MA, Tijssen MAJ, van den Maagdenberg AMJM, Depienne C. Unstable TTTTA/TTTCA expansions in MARCH6 are associated with Familial Adult Myoclonic Epilepsy type 3. Nat Commun 2019; 10:4919. [PMID: 31664039 PMCID: PMC6820781 DOI: 10.1038/s41467-019-12763-9] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 09/23/2019] [Indexed: 12/30/2022] Open
Abstract
Familial Adult Myoclonic Epilepsy (FAME) is a genetically heterogeneous disorder characterized by cortical tremor and seizures. Intronic TTTTA/TTTCA repeat expansions in SAMD12 (FAME1) are the main cause of FAME in Asia. Using genome sequencing and repeat-primed PCR, we identify another site of this repeat expansion, in MARCH6 (FAME3) in four European families. Analysis of single DNA molecules with nanopore sequencing and molecular combing show that expansions range from 3.3 to 14 kb on average. However, we observe considerable variability in expansion length and structure, supporting the existence of multiple expansion configurations in blood cells and fibroblasts of the same individual. Moreover, the largest expansions are associated with micro-rearrangements occurring near the expansion in 20% of cells. This study provides further evidence that FAME is caused by intronic TTTTA/TTTCA expansions in distinct genes and reveals that expansions exhibit an unexpectedly high somatic instability that can ultimately result in genomic rearrangements.
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Affiliation(s)
- Rahel T Florian
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Florian Kraft
- Institute of Human Genetics, Medical Faculty, RWTH Aachen University, 52062, Aachen, Germany
| | - Elsa Leitão
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Sabine Kaya
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Stephan Klebe
- Department of Neurology, Universitätsklinikum Essen, Universität Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Eloi Magnin
- Department of Neurology, CHU Jean Minjoz, 25000, Besançon, France
| | - Anne-Fleur van Rootselaar
- Departments of Neurology and Clinical Neurophysiology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Meibergdreef 9, 1105, AZ, Amsterdam, The Netherlands
| | - Julien Buratti
- AP-HP, Hôpital Pitié-Salpêtrière, Département de Génétique, 75013, Paris, France
| | - Theresa Kühnel
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Christopher Schröder
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Sebastian Giesselmann
- Institute of Human Genetics, Medical Faculty, RWTH Aachen University, 52062, Aachen, Germany
| | - Nikolai Tschernoster
- Cologne Center for Genomics, Center for Molecular Medicine Cologne (CMMC), University of Cologne, Weyertal 115b, 50931, Cologne, Germany
| | - Janine Altmueller
- Cologne Center for Genomics, Center for Molecular Medicine Cologne (CMMC), University of Cologne, Weyertal 115b, 50931, Cologne, Germany
| | - Anaide Lamiral
- Department of Neurology, CHU Jean Minjoz, 25000, Besançon, France
| | - Boris Keren
- AP-HP, Hôpital Pitié-Salpêtrière, Département de Génétique, 75013, Paris, France
| | - Caroline Nava
- AP-HP, Hôpital Pitié-Salpêtrière, Département de Génétique, 75013, Paris, France
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
| | - Delphine Bouteiller
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
| | - Sylvie Forlani
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
| | - Ludmila Jornea
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
| | - Regina Kubica
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Tao Ye
- IGBMC, CNRS UMR 7104/INSERM U1258/Université de Strasbourg, 1 Rue Laurent Fries, 67400, Illkirch-Graffenstaden, France
| | - Damien Plassard
- IGBMC, CNRS UMR 7104/INSERM U1258/Université de Strasbourg, 1 Rue Laurent Fries, 67400, Illkirch-Graffenstaden, France
| | - Bernard Jost
- IGBMC, CNRS UMR 7104/INSERM U1258/Université de Strasbourg, 1 Rue Laurent Fries, 67400, Illkirch-Graffenstaden, France
| | - Vincent Meyer
- Centre National de Recherche en Génomique Humaine (CNRGH), Institut de Biologie François Jacob, CEA, Université Paris-Saclay, F-91057, Evry, France
| | - Jean-François Deleuze
- Centre National de Recherche en Génomique Humaine (CNRGH), Institut de Biologie François Jacob, CEA, Université Paris-Saclay, F-91057, Evry, France
| | - Yannick Delpu
- Genomic Vision, 80 Rue des Meuniers, 92220, Bagneux, France
| | | | - Lisanne S Vijfhuizen
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333, ZA, Leiden, The Netherlands
| | - Gabrielle Rudolf
- IGBMC, CNRS UMR 7104/INSERM U1258/Université de Strasbourg, 1 Rue Laurent Fries, 67400, Illkirch-Graffenstaden, France
- Department of Neurology-centre de référence des epilepsies rares, University Hospital of Strasbourg, 1 Avenue Molière, 67200, Strasbourg, France
| | - Edouard Hirsch
- Department of Neurology-centre de référence des epilepsies rares, University Hospital of Strasbourg, 1 Avenue Molière, 67200, Strasbourg, France
| | - Thessa Kroes
- School of Biological Sciences, School of Medicine and Robinson Research Institute, The University of Adelaide, Adelaide, 5005, SA, Australia
| | - Philipp S Reif
- Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Goethe University and LOEWE Center for Personalized Translational Epilepsy Research (CePTER), 60323, Frankfurt am Main, Germany
- Department of Neurology, Epilepsy Center Hessen, Philipps University, 35037, Marburg, Germany
| | - Felix Rosenow
- Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Goethe University and LOEWE Center for Personalized Translational Epilepsy Research (CePTER), 60323, Frankfurt am Main, Germany
- Department of Neurology, Epilepsy Center Hessen, Philipps University, 35037, Marburg, Germany
| | - Christos Ganos
- Department of Neurology, Charité University Medicine Berlin, 10117, Berlin, Germany
| | - Marie Vidailhet
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
- APHP, Hôpital Pitié-Salpêtrière, Département de Neurologie, 75013, Paris, France
| | - Lionel Thivard
- APHP, Hôpital Pitié-Salpêtrière, Département de Neurologie, 75013, Paris, France
| | - Alexandre Mathieu
- Human Genetics and Cognitive Functions, Pasteur Institute, UMR3571 CNRS, Université de Paris, 75015, Paris, France
| | - Thomas Bourgeron
- Human Genetics and Cognitive Functions, Pasteur Institute, UMR3571 CNRS, Université de Paris, 75015, Paris, France
| | - Ingo Kurth
- Institute of Human Genetics, Medical Faculty, RWTH Aachen University, 52062, Aachen, Germany
| | - Haloom Rafehi
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, VIC, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, 3010, VIC, Australia
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, 3084, VIC, Australia
| | - Laura Steenpass
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Bernhard Horsthemke
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Eric LeGuern
- AP-HP, Hôpital Pitié-Salpêtrière, Département de Génétique, 75013, Paris, France
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
| | - Karl Martin Klein
- Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Goethe University and LOEWE Center for Personalized Translational Epilepsy Research (CePTER), 60323, Frankfurt am Main, Germany
- Department of Neurology, Epilepsy Center Hessen, Philipps University, 35037, Marburg, Germany
- Departments of Clinical Neurosciences, Medical Genetics and Community Health Sciences, Hotchkiss Brain Institute & Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, 2500 University Dr NW, Calgary, AB, T2N 1N4, Canada
| | - Pierre Labauge
- Department of Neurology, Gui de Chauliac University Hospital, 34295, Montpellier, France
| | - Mark F Bennett
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, VIC, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, 3010, VIC, Australia
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, 3084, VIC, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, VIC, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, 3010, VIC, Australia
| | - Jozef Gecz
- School of Biological Sciences, School of Medicine and Robinson Research Institute, The University of Adelaide, Adelaide, 5005, SA, Australia
- South Australian Health and Medical Research Institute, The University of Adelaide, Adelaide, 5005, SA, Australia
| | - Mark A Corbett
- School of Biological Sciences, School of Medicine and Robinson Research Institute, The University of Adelaide, Adelaide, 5005, SA, Australia
| | - Marina A J Tijssen
- Department of Neurology, University Medical Center Groningen, University of Groningen, 9700, AB, Groningen, the Netherlands
| | - Arn M J M van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333, ZA, Leiden, The Netherlands
- Department of Neurology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany.
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France.
- IGBMC, CNRS UMR 7104/INSERM U1258/Université de Strasbourg, 1 Rue Laurent Fries, 67400, Illkirch-Graffenstaden, France.
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46
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Valosin-containing protein mediates the ERAD of squalene monooxygenase and its cholesterol-responsive degron. Biochem J 2019; 476:2545-2560. [DOI: 10.1042/bcj20190418] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/27/2019] [Accepted: 08/29/2019] [Indexed: 12/17/2022]
Abstract
AbstractSqualene monooxygenase (SM) is an essential rate-limiting enzyme in cholesterol synthesis. SM degradation is accelerated by excess cholesterol, and this requires the first 100 amino acids of SM (SM N100). This process is part of a protein quality control pathway called endoplasmic reticulum-associated degradation (ERAD). In ERAD, SM is ubiquitinated by MARCH6, an E3 ubiquitin ligase located in the endoplasmic reticulum (ER). However, several details of the ERAD process for SM remain elusive, such as the extraction mechanism from the ER membrane. Here, we used SM N100 fused to GFP (SM N100-GFP) as a model degron to investigate the extraction process of SM in ERAD. We showed that valosin-containing protein (VCP) is important for the cholesterol-accelerated degradation of SM N100-GFP and SM. In addition, we revealed that VCP acts following ubiquitination of SM N100-GFP by MARCH6. We demonstrated that the amphipathic helix (Gln62–Leu73) of SM N100-GFP is critical for regulation by VCP and MARCH6. Replacing this amphipathic helix with hydrophobic re-entrant loops promoted degradation in a VCP-dependent manner. Finally, we showed that inhibiting VCP increases cellular squalene and cholesterol levels, indicating a functional consequence for VCP in regulating the cholesterol synthesis pathway. Collectively, we established VCP plays a key role in ERAD that contributes to the cholesterol-mediated regulation of SM.
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McClellan AJ, Laugesen SH, Ellgaard L. Cellular functions and molecular mechanisms of non-lysine ubiquitination. Open Biol 2019; 9:190147. [PMID: 31530095 PMCID: PMC6769291 DOI: 10.1098/rsob.190147] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Protein ubiquitination is of great cellular importance through its central role in processes such as degradation, DNA repair, endocytosis and inflammation. Canonical ubiquitination takes place on lysine residues, but in the past 15 years non-lysine ubiquitination on serine, threonine and cysteine has been firmly established. With the emerging importance of non-lysine ubiquitination, it is crucial to identify the responsible molecular machinery and understand the mechanistic basis for non-lysine ubiquitination. Here, we first provide an overview of the literature that has documented non-lysine ubiquitination. Informed by these examples, we then discuss the molecular mechanisms and cellular implications of non-lysine ubiquitination, and conclude by outlining open questions and future perspectives in the field.
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Affiliation(s)
- Amie J McClellan
- Division of Science and Mathematics, Bennington College, 1 College Drive, Bennington, VT 05201, USA
| | - Sophie Heiden Laugesen
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Lars Ellgaard
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen N, Denmark
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48
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Chua NK, Hart-Smith G, Brown AJ. Non-canonical ubiquitination of the cholesterol-regulated degron of squalene monooxygenase. J Biol Chem 2019; 294:8134-8147. [PMID: 30940729 DOI: 10.1074/jbc.ra119.007798] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/11/2019] [Indexed: 12/21/2022] Open
Abstract
Squalene monooxygenase (SM) is a rate-limiting enzyme in cholesterol synthesis. The region comprising the first 100 amino acids, termed SM N100, represents the shortest cholesterol-responsive degron and enables SM to sense excess cholesterol in the endoplasmic reticulum (ER) membrane. Cholesterol accelerates the ubiquitination of SM by membrane-associated ring-CH type finger 6 (MARCH6), a key E3 ubiquitin ligase involved in ER-associated degradation. However, the ubiquitination site required for cholesterol regulation of SM N100 is unknown. Here, we used SM N100 fused to GFP as a model degron to recapitulate cholesterol-mediated SM degradation and show that neither SM lysine residues nor the N terminus impart instability. Instead, we discovered four serines (Ser-59, Ser-61, Ser-83, and Ser-87) that are critical for cholesterol-accelerated degradation, with MS analysis confirming Ser-83 as a ubiquitination site. Notably, these two clusters of closely spaced serine residues are located in disordered domains flanking a 12-amino acid-long amphipathic helix (residues Gln-62-Leu-73) that together confer cholesterol responsiveness. In summary, our findings reveal the degron architecture of SM N100, introducing the role of non-canonical ubiquitination sites and deepening our molecular understanding of how SM is degraded in response to cholesterol.
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Affiliation(s)
- Ngee Kiat Chua
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, New South Wales 2052, Australia
| | - Gene Hart-Smith
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, New South Wales 2052, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, New South Wales 2052, Australia.
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49
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Abstract
Identification and degradation of misfolded proteins by the ubiquitin-proteasome system (UPS) is crucial for maintaining proteostasis, but only a handful of UPS components have been linked to the recognition of specific substrates. Studies in Saccharomyces cerevisiae using systematic perturbation of nonessential genes have uncovered UPS components that recognize and ubiquitylate model substrates of the UPS; however, similar analyses in metazoans have been limited. In this chapter, we describe methods for using CRISPR/Cas9 technology combined with genome-wide high complexity single guide (sgRNA) libraries and a transcriptional shutoff strategy for phenotypic selection based on kinetic measurements of protein turnover to identify the genes required to degrade model clients of the mammalian ER-associated degradation system. We also discuss considerations for screen design, execution, and interpretation.
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Affiliation(s)
- Dara E Leto
- Department of Biology, Stanford University, Stanford, CA, United States
| | - Ron R Kopito
- Department of Biology, Stanford University, Stanford, CA, United States.
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50
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Chen J, Guo H, Jiang H, Namusamba M, Wang C, Lan T, Wang T, Wang B. A BAP31 intrabody induces gastric cancer cell death by inhibiting p27
kip1
proteasome degradation. Int J Cancer 2019; 144:2051-2062. [DOI: 10.1002/ijc.31930] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/15/2018] [Accepted: 10/09/2018] [Indexed: 01/26/2023]
Affiliation(s)
- Jing Chen
- College of Life and Health ScienceNortheastern University Shenyang Liaoning Province People's Republic of China
| | - Haotian Guo
- College of Life and Health ScienceNortheastern University Shenyang Liaoning Province People's Republic of China
| | - Haitao Jiang
- Dasan Medichem (Shenyang) R&D center Shenyang Liaoning Province People's Republic of China
| | - Mwichie Namusamba
- College of Life and Health ScienceNortheastern University Shenyang Liaoning Province People's Republic of China
| | - Changli Wang
- College of Life and Health ScienceNortheastern University Shenyang Liaoning Province People's Republic of China
| | - Tian Lan
- College of Life and Health ScienceNortheastern University Shenyang Liaoning Province People's Republic of China
| | - Tianyi Wang
- College of Life and Health ScienceNortheastern University Shenyang Liaoning Province People's Republic of China
| | - Bing Wang
- College of Life and Health ScienceNortheastern University Shenyang Liaoning Province People's Republic of China
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