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Cairo LV, Hong X, Müller MBD, Yuste-Checa P, Jagadeesan C, Bracher A, Park SH, Hayer-Hartl M, Hartl FU. Stress-dependent condensate formation regulated by the ubiquitin-related modifier Urm1. Cell 2024; 187:4656-4673.e28. [PMID: 38942013 DOI: 10.1016/j.cell.2024.06.009] [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: 08/27/2023] [Revised: 04/12/2024] [Accepted: 06/08/2024] [Indexed: 06/30/2024]
Abstract
The ability of proteins and RNA to coalesce into phase-separated assemblies, such as the nucleolus and stress granules, is a basic principle in organizing membraneless cellular compartments. While the constituents of biomolecular condensates are generally well documented, the mechanisms underlying their formation under stress are only partially understood. Here, we show in yeast that covalent modification with the ubiquitin-like modifier Urm1 promotes the phase separation of a wide range of proteins. We find that the drop in cellular pH induced by stress triggers Urm1 self-association and its interaction with both target proteins and the Urm1-conjugating enzyme Uba4. Urmylation of stress-sensitive proteins promotes their deposition into stress granules and nuclear condensates. Yeast cells lacking Urm1 exhibit condensate defects that manifest in reduced stress resilience. We propose that Urm1 acts as a reversible molecular "adhesive" to drive protective phase separation of functionally critical proteins under cellular stress.
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Affiliation(s)
- Lucas V Cairo
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Xiaoyu Hong
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Martin B D Müller
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Patricia Yuste-Checa
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Chandhuru Jagadeesan
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Andreas Bracher
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Sae-Hun Park
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - Manajit Hayer-Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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2
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Fang R, Bai L, Li B, Dong K, Paulo JA, Zhou M, Chu YC, Song Y, Sherman MY, Gygi S, Field CM, Mitchison TJ, Lu Y. Episodic Transport of Protein Aggregates Achieves a Positive Size Selectivity in Aggresome Formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.06.606767. [PMID: 39211171 PMCID: PMC11361152 DOI: 10.1101/2024.08.06.606767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Eukaryotic cells direct toxic misfolded proteins to various protein quality control pathways based on their chemical features and aggregation status. Aggregated proteins are targeted to selective autophagy or specifically sequestered into the "aggresome," a perinuclear inclusion at the microtubule-organizing center (MTOC). However, the mechanism for selectively sequestering protein aggregates into the aggresome remains unclear. To investigate aggresome formation, we reconstituted MTOC-directed aggregate transport in Xenopus laevis egg extract using AgDD, a chemically inducible aggregation system. High-resolution single-particle tracking revealed that dynein-mediated transport of aggregates was highly episodic, with average velocity positively correlated with aggregate size. Our mechanistic model suggests that the recurrent formation of the dynein transport complex biases larger aggregates towards the active transport state, compensating for the slowdown due to viscosity. Both episodic transport and positive size selectivity are specifically associated with aggresome-dynein adaptors. Coupling conventional dynein-activating adaptors to the aggregates perturbs aggresome formation and reverses size selectivity.
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3
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Johnson DL, Kumar R, Kakhniashvili D, Pfeffer LM, Laribee RN. Ccr4-not ubiquitin ligase signaling regulates ribosomal protein homeostasis and inhibits 40S ribosomal autophagy. J Biol Chem 2024; 300:107582. [PMID: 39025453 PMCID: PMC11357857 DOI: 10.1016/j.jbc.2024.107582] [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: 12/18/2023] [Revised: 06/27/2024] [Accepted: 07/10/2024] [Indexed: 07/20/2024] Open
Abstract
The Ccr4-Not complex contains the poorly understood Not4 ubiquitin ligase that functions in transcription, mRNA decay, translation, proteostasis, and endolysosomal nutrient signaling. To gain further insight into the in vivo functions of the ligase, we performed quantitative proteomics in Saccharomyces cerevisiae using yeast cells lacking Not4, or cells overexpressing wild-type Not4 or an inactive Not4 mutant. Herein, we provide evidence that balanced Not4 activity maintains ribosomal protein (RP) homeostasis independent of changes to RP mRNA or known Not4 ribosomal substrates. Intriguingly, we also find that Not4 loss activates 40S ribosomal autophagy independently of canonical Atg7-dependent macroautophagy, indicating that microautophagy is responsible. We previously demonstrated that Ccr4-Not stimulates the target of rapamycin complex 1 (TORC1) signaling, which activates RP expression and inhibits autophagy, by maintaining vacuole V-ATPase H+ pump activity. Importantly, combining Not4 deficient cells with a mutant that blocks vacuole H+ export fully restores RP expression and increases 40S RP autophagy efficiency. In contrast, restoring TORC1 activity alone fails to rescue either process, indicating that Not4 loss disrupts additional endolysosomal functions that regulate RP expression and 40S autophagy. Analysis of the Not4-regulated proteome reveals increases in endolysosomal and autophagy-related factors that functionally interact with Not4 to control RP expression and affect 40S autophagy. Collectively, our data indicate that balanced Ccr4-Not ubiquitin ligase signaling maintains RP homeostasis and inhibits 40S autophagy via the ligase's emerging role as an endolysosomal regulator.
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Affiliation(s)
- Daniel L Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Ravinder Kumar
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - David Kakhniashvili
- Proteomics and Metabolomics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Lawrence M Pfeffer
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - R Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
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4
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Sharma I, Talakayala A, Tiwari M, Asinti S, Kirti PB. A synchronized symphony: Intersecting roles of ubiquitin proteasome system and autophagy in cellular degradation. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 212:108700. [PMID: 38781635 DOI: 10.1016/j.plaphy.2024.108700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 05/01/2024] [Indexed: 05/25/2024]
Abstract
Eukaryotic cells have evolved dynamic quality control pathways and recycling mechanisms for cellular homeostasis. We discuss here, the two major systems for quality control, the ubiquitin-proteasome system (UPS) and autophagy that regulate cellular protein and organelle turnover and ensure efficient nutrient management, cellular integrity and long-term wellbeing of the plant. Both the pathways rely on ubiquitination signal to identify the targets for proteasomal and autophagic degradation, yet they use distinct degradation machinery to process these cargoes. Nonetheless, both UPS and autophagy operate together as an interrelated quality control mechanism where they communicate with each other at multiple nodes to coordinate and/or compensate the recycling mechanism particularly under development and environmental cues. Here, we provide an update on the cellular machinery of autophagy and UPS, unravel the nodes of their crosstalk and particularly highlight the factors responsible for their differential deployment towards protein, macromolecular complexes and organelles.
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Affiliation(s)
- Isha Sharma
- International Crop Research Institute for Semi-Arid Tropics, Patancheru, Hyderabad, India, 502324.
| | - Ashwini Talakayala
- International Crop Research Institute for Semi-Arid Tropics, Patancheru, Hyderabad, India, 502324
| | - Manish Tiwari
- CSIR-National Botanical Research Institute, 435, Rana Pratap Marg, Lucknow, 226001, Uttar Pradesh, India
| | - Sarath Asinti
- Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, 211007, India
| | - P B Kirti
- Agri Biotech Foundation, Rajendranagar, 500030, Hyderabad, India
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5
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Zhao DY, Bäuerlein FJB, Saha I, Hartl FU, Baumeister W, Wilfling F. Autophagy preferentially degrades non-fibrillar polyQ aggregates. Mol Cell 2024; 84:1980-1994.e8. [PMID: 38759629 DOI: 10.1016/j.molcel.2024.04.018] [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: 08/08/2023] [Revised: 01/30/2024] [Accepted: 04/23/2024] [Indexed: 05/19/2024]
Abstract
Aggregation of proteins containing expanded polyglutamine (polyQ) repeats is the cytopathologic hallmark of a group of dominantly inherited neurodegenerative diseases, including Huntington's disease (HD). Huntingtin (Htt), the disease protein of HD, forms amyloid-like fibrils by liquid-to-solid phase transition. Macroautophagy has been proposed to clear polyQ aggregates, but the efficiency of aggrephagy is limited. Here, we used cryo-electron tomography to visualize the interactions of autophagosomes with polyQ aggregates in cultured cells in situ. We found that an amorphous aggregate phase exists next to the radially organized polyQ fibrils. Autophagosomes preferentially engulfed this amorphous material, mediated by interactions between the autophagy receptor p62/SQSTM1 and the non-fibrillar aggregate surface. In contrast, amyloid fibrils excluded p62 and evaded clearance, resulting in trapping of autophagic structures. These results suggest that the limited efficiency of autophagy in clearing polyQ aggregates is due to the inability of autophagosomes to interact productively with the non-deformable, fibrillar disease aggregates.
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Affiliation(s)
- Dorothy Y Zhao
- Max Planck Institute of Biochemistry, Molecular Machines and Signaling, 82152 Martinsried, Germany; Max Planck Institute of Biochemistry, Molecular Structural Biology, 82152 Martinsried, Germany; Max Planck Institute of Biophysics, Mechanisms of Cellular Quality Control, 60438 Frankfurt, Germany; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA.
| | - Felix J B Bäuerlein
- Max Planck Institute of Biochemistry, Molecular Structural Biology, 82152 Martinsried, Germany; University Medical Center Göttingen, Institute of Neuropathology, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany
| | - Itika Saha
- Max Planck Institute of Biochemistry, Cellular Biochemistry, 82152 Martinsried, Germany; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - F Ulrich Hartl
- Max Planck Institute of Biochemistry, Cellular Biochemistry, 82152 Martinsried, Germany; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA.
| | - Wolfgang Baumeister
- Max Planck Institute of Biochemistry, Molecular Structural Biology, 82152 Martinsried, Germany; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA.
| | - Florian Wilfling
- Max Planck Institute of Biochemistry, Molecular Machines and Signaling, 82152 Martinsried, Germany; Max Planck Institute of Biochemistry, Molecular Structural Biology, 82152 Martinsried, Germany; Max Planck Institute of Biophysics, Mechanisms of Cellular Quality Control, 60438 Frankfurt, Germany; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA.
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6
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Mei L, Chen X, Wei F, Huang X, Liu L, Yao J, Chen J, Luo X, Wang Z, Yang A. Tethering ATG16L1 or LC3 induces targeted autophagic degradation of protein aggregates and mitochondria. Autophagy 2023; 19:2997-3013. [PMID: 37424101 PMCID: PMC10549199 DOI: 10.1080/15548627.2023.2234797] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 06/23/2023] [Accepted: 07/05/2023] [Indexed: 07/11/2023] Open
Abstract
Proteolysis-targeting chimeras (PROTACs) based on the ubiquitin-proteasome system have made great progress in the field of drug discovery. There is mounting evidence that the accumulation of aggregation-prone proteins or malfunctioning organelles is associated with the occurrence of various age-related neurodegenerative disorders and cancers. However, PROTACs are inefficient for the degradation of such large targets due to the narrow entrance channel of the proteasome. Macroautophagy (hereafter referred to as autophagy) is known as a self-degradative process involved in the degradation of bulk cytoplasmic components or specific cargoes that are sequestered into autophagosomes. In the present study, we report the development of a generalizable strategy for the targeted degradation of large targets. Our results suggested that tethering large target models to phagophore-associated ATG16L1 or LC3 induced targeted autophagic degradation of the large target models. Furthermore, we successfully applied this autophagy-targeting degradation strategy to the targeted degradation of HTT65Q aggregates and mitochondria. Specifically, chimeras consisting of polyQ-binding peptide 1 (QBP) and ATG16L1-binding peptide (ABP) or LC3-interacting region (LIR) induced targeted autophagic degradation of pathogenic HTT65Q aggregates; and the chimeras consisting of mitochondria-targeting sequence (MTS) and ABP or LIR promoted targeted autophagic degradation of dysfunctional mitochondria, hence ameliorating mitochondrial dysfunction in a Parkinson disease cell model and protecting cells from apoptosis induced by the mitochondrial stress agent FCCP. Therefore, this study provides a new strategy for the selective proteolysis of large targets and enrich the toolkit for autophagy-targeting degradation.Abbreviations: ABP: ATG16L1-binding peptide; ATG16L1: autophagy related 16 like 1; ATTEC: autophagy-tethering compound; AUTAC: autophagy-targeting chimera; AUTOTAC: autophagy-targeting chimera; Baf A1: bafilomycin A1; BCL2: BCL2 apoptosis regulator; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CASP3: caspase 3; CPP: cell-penetrating peptide; CQ: chloroquine phosphate; DAPI: 4',6-diamidino-2-phenylindole; DCM: dichloromethane; DMF: N,N-dimethylformamide; DMSO: dimethyl sulfoxide; EBSS: Earle's balanced salt solution; FCCP: carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone; FITC: fluorescein-5-isothiocyanate; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; HEK293: human embryonic kidney 293; HEK293T: human embryonic kidney 293T; HPLC: high-performance liquid chromatography; HRP: horseradish peroxidase; HTT: huntingtin; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MFF: mitochondrial fission factor; MTS: mitochondria-targeting sequence; NBR1: NBR1 autophagy cargo receptor; NLRX1: NLR family member X1; OPTN: optineurin; P2A: self-cleaving 2A peptide; PB1: Phox and Bem1p; PBS: phosphate-buffered saline; PE: phosphatidylethanolamine; PINK1: PTEN induced kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; PROTACs: proteolysis-targeting chimeras; QBP: polyQ-binding peptide 1; SBP: streptavidin-binding peptide; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SPATA33: spermatogenesis associated 33; TIMM23: translocase of inner mitochondrial membrane 23; TMEM59: transmembrane protein 59; TOMM20: translocase of outer mitochondrial membrane 20; UBA: ubiquitin-associated; WT: wild type.
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Affiliation(s)
- Ligang Mei
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Xiaorong Chen
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Fujing Wei
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Xue Huang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lu Liu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Jia Yao
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Jing Chen
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Xunguang Luo
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Zhuolin Wang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing, China
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7
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Mensah TNA, Shroff A, Nazarko TY. Ubiquitin-binding autophagic receptors in yeast: Cue5 and beyond. Autophagy 2023; 19:2590-2594. [PMID: 37062912 PMCID: PMC10392746 DOI: 10.1080/15548627.2023.2196878] [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: 12/30/2022] [Revised: 03/01/2023] [Accepted: 03/24/2023] [Indexed: 04/18/2023] Open
Abstract
The selectivity in selective macroautophagy/autophagy pathways is achieved via selective autophagy receptors (SARs) - proteins that bind a ligand on the substrate to be degraded and an Atg8-family protein on the growing autophagic membrane, phagophore, effectively bridging them. In mammals, the most common ligand of SARs is ubiquitin, a small protein modifier that tags substrates for their preferential degradation by autophagy. Consequently, most common SARs are ubiquitin-binding SARs, such as SQSTM1/p62 (sequestosome 1). Surprisingly, there is only one SAR of this type in yeast - Cue5, which acts as the receptor for aggrephagy and proteaphagy - pathways that remove ubiquitinated protein aggregates and proteasomes, respectively. However, recent studies described ubiquitin-dependent autophagic pathways that do not require Cue5, e.g. the stationary phase lipophagy for lipid droplets or nitrogen starvation-induced mitophagy for mitochondria. What is the role of ubiquitin in these pathways? Here, we propose that ubiquitinated lipid droplets and mitochondria are recognized by alternative ubiquitin-binding SARs. Our analysis identifies proteins that could potentially fulfill this role in yeast. We think that matching of ubiquitin-dependent (but Cue5-independent) autophagic pathways with ubiquitin- and Atg8-binding proteins enlisted here might uncover novel ubiquitin-binding SARs in yeast.Abbreviations: AIM: Atg8-family interacting motif; CUE: coupling of ubiquitin conjugation to ER degradation; ERMES: endoplasmic reticulum-mitochondria encounter structure; HECT: homologous to the E6-AP carboxyl terminus; LD: lipid droplet; SAR: selective autophagy receptor; SGD: Saccharomyces Genome Database; UBA: ubiquitin-associated; UBX: ubiquitin regulatory X; UIM: ubiquitin-interacting motif.
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Affiliation(s)
| | - Ankit Shroff
- Department of Biology, Georgia State University, Atlanta, GA, USA
| | - Taras Y. Nazarko
- Department of Biology, Georgia State University, Atlanta, GA, USA
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8
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Johnson DL, Kumar R, Kakhniashvili D, Pfeffer LM, Laribee RN. Ccr4-Not ubiquitin ligase signaling regulates ribosomal protein homeostasis and inhibits 40S ribosomal autophagy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555095. [PMID: 37693548 PMCID: PMC10491097 DOI: 10.1101/2023.08.28.555095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The Ccr4-Not complex containing the Not4 ubiquitin ligase regulates gene transcription and mRNA decay, yet it also has poorly defined roles in translation, proteostasis, and endolysosomal-dependent nutrient signaling. To define how Ccr4-Not mediated ubiquitin signaling regulates these additional processes, we performed quantitative proteomics in the yeast Saccharomyces cerevisiae lacking the Not4 ubiquitin ligase, and also in cells overexpressing either wild-type or functionally inactive ligase. Herein, we provide evidence that both increased and decreased Ccr4-Not ubiquitin signaling disrupts ribosomal protein (RP) homeostasis independently of reduced RP mRNA changes or reductions in known Not4 ribosomal substrates. Surprisingly, we also find that both Not4-mediated ubiquitin signaling, and the Ccr4 subunit, actively inhibit 40S ribosomal autophagy. This 40S autophagy is independent of canonical Atg7-dependent macroautophagy, thus indicating microautophagy activation is responsible. Furthermore, the Not4 ligase genetically interacts with endolysosomal pathway effectors to control both RP expression and 40S autophagy efficiency. Overall, we demonstrate that balanced Ccr4-Not ligase activity maintains RP homeostasis, and that Ccr4-Not ubiquitin signaling interacts with the endolysosomal pathway to both regulate RP expression and inhibit 40S ribosomal autophagy.
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Affiliation(s)
- Daniel L. Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Ravinder Kumar
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - David Kakhniashvili
- Proteomics and Metabolomics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Lawrence M. Pfeffer
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
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9
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Folger A, Chen C, Kabbaj MH, Frey K, Wang Y. Neurodegenerative disease-associated inclusion bodies are cleared by selective autophagy in budding yeast. AUTOPHAGY REPORTS 2023; 2:2236407. [PMID: 37680383 PMCID: PMC10482306 DOI: 10.1080/27694127.2023.2236407] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 06/13/2023] [Accepted: 07/06/2023] [Indexed: 09/09/2023]
Abstract
Protein misfolding, aggregation, and accumulation cause neurodegenerative disorders. One such disorder, Huntington's disease, is caused by an increased number of glutamine-encoding trinucleotide repeats CAG in the first exon of the huntingtin (HTT) gene. Mutant proteins of Htt exon 1 with polyglutamine expansion are prone to aggregation and form pathological inclusion bodies in neurons. Extensive studies have shown that misfolded proteins are cleared by the ubiquitin-proteasome system or autophagy to alleviate their cytotoxicity. Misfolded proteins can form small soluble aggregates or large insoluble inclusion bodies. Previous works have elucidated the role of autophagy in the clearance of misfolded protein aggregates, but autophagic clearance of inclusion bodies remains poorly characterized. Here we use mutant Htt exon 1 with 103 polyglutamine (Htt103QP) as a model substrate to study the autophagic clearance of inclusion bodies in budding yeast. We found that the core autophagy-related proteins were required for Htt103QP inclusion body autophagy. Moreover, our evidence indicates that the autophagy of Htt103QP inclusion bodies is selective. Interestingly, Cue5/Tollip, a known autophagy receptor for aggrephagy, is dispensable for this inclusion body autophagy. From the known selective autophagy receptors in budding yeast, we identified three that are essential for inclusion body autophagy. Amyloid beta peptide (Aβ42) is a major component of amyloid plaques found in Alzheimer's disease brains. Interestingly, a similar selective autophagy pathway contributes to the clearance of Aβ42 inclusion bodies in budding yeast. Therefore, our results reveal a novel autophagic pathway specific for inclusion bodies associated with neurodegenerative diseases, which we have termed IBophagy.
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Affiliation(s)
- Austin Folger
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306-4300
| | - Chuan Chen
- College of Biological Sciences, Hebei University, Baoding, China
| | - Marie-Helene Kabbaj
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306-4300
| | - Karina Frey
- Department of Biological Sciences, Florida State University (undergraduate student)
| | - Yanchang Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306-4300
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10
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Raffeiner M, Zhu S, González-Fuente M, Üstün S. Interplay between autophagy and proteasome during protein turnover. TRENDS IN PLANT SCIENCE 2023; 28:698-714. [PMID: 36801193 DOI: 10.1016/j.tplants.2023.01.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 01/13/2023] [Accepted: 01/26/2023] [Indexed: 05/13/2023]
Abstract
Protein homeostasis is epitomized by an equilibrium between protein biosynthesis and degradation: the 'life and death' of proteins. Approximately one-third of newly synthesized proteins are degraded. As such, protein turnover is required to maintain cellular integrity and survival. Autophagy and the ubiquitin-proteasome system (UPS) are the two principal degradation pathways in eukaryotes. Both pathways orchestrate many cellular processes during development and upon environmental stimuli. Ubiquitination of degradation targets is used as a 'death' signal by both processes. Recent findings revealed a direct functional link between both pathways. Here, we summarize key findings in the field of protein homeostasis, with an emphasis on the newly revealed crosstalk between both degradation machineries and how it is decided which pathway facilitates target degradation.
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Affiliation(s)
- Margot Raffeiner
- Eberhard-Karls-Universität Tübingen, Zentrum für Molekular Biologie der Pflanzen, 72076 Tübingen, Germany; Faculty of Biology & Biotechnology, Ruhr-University of Bochum, 44780 Bochum, Germany
| | - Shanshuo Zhu
- Eberhard-Karls-Universität Tübingen, Zentrum für Molekular Biologie der Pflanzen, 72076 Tübingen, Germany; Faculty of Biology & Biotechnology, Ruhr-University of Bochum, 44780 Bochum, Germany
| | - Manuel González-Fuente
- Eberhard-Karls-Universität Tübingen, Zentrum für Molekular Biologie der Pflanzen, 72076 Tübingen, Germany; Faculty of Biology & Biotechnology, Ruhr-University of Bochum, 44780 Bochum, Germany
| | - Suayib Üstün
- Eberhard-Karls-Universität Tübingen, Zentrum für Molekular Biologie der Pflanzen, 72076 Tübingen, Germany; Faculty of Biology & Biotechnology, Ruhr-University of Bochum, 44780 Bochum, Germany.
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11
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Dong B, Li F, Wang J, Lv S, Miao L, Guo G, Shen Z. Effect of ubiquitin-proteasome system and autophagy-lysosome pathway on intracellular replication of Brucella.suis. Vet Microbiol 2023; 280:109699. [PMID: 36812863 DOI: 10.1016/j.vetmic.2023.109699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 01/08/2023] [Accepted: 02/15/2023] [Indexed: 02/18/2023]
Abstract
The ubiquitin-proteasome system (UPS) and autophagy-lysosome pathway (ALP) are two major protein degradation pathways in eukaryotic cells. In the present study, we investigated the role of two systems and their interaction after Brucella.suis (B.suis) infected RAW264.7 murine macrophage. We demonstrated that B.suis activated ALP by upregulating LC3-Ⅱlevels as well as incomplete inhibition of P62 expression in RAW264.7 cells. On the other hand, we used pharmacological agents to confirm that ALP contributed the intracellular proliferation of B.suis. At present, the studies on the relationship between UPS and Brucella remain less understanding. In the study, we demonstrated that UPS machinery was also activated by promoting expression of 20 s proteasome after B.suis infected RAW264.7 cells, and that, the UPS could also promote intracellular proliferation of B.suis. Many recent studies propose the close link and dynamic interconversion between UPS and ALP. Currently, the experiments demonstrated that after RAW264.7 cells infected B.suis, ALP was activated following UPS inhibition, while the UPS was not effectively activated after ALP inhibition. Last, we compared the ability to promote intracellular proliferation of B.suis between UPS and ALP. The results displayed that the ability of UPS to promote intracellular proliferation of B.suis was stronger than that of ALP, and simultaneous inhibition of UPS and ALP led to seriously affection on intracellular proliferation of B.suis. All above, our research provides a better understanding on the interaction between Brucella and both systems.
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Affiliation(s)
- Bingmei Dong
- College of Life Science, Cangzhou Normal University, Guofeng South Avenue 16#, Cangzhou 061001, Hebei, China; Shandong Lvdu Biological Technology Co. Ltd, Binzhou 256600, Shandong, China
| | - Feng Li
- Binzhou Animal Science and Veterinary Medicine Academy, Binzhou 256600, Shandong, China
| | - Jinliang Wang
- Binzhou Animal Science and Veterinary Medicine Academy, Binzhou 256600, Shandong, China
| | - Sufang Lv
- Binzhou Animal Science and Veterinary Medicine Academy, Binzhou 256600, Shandong, China
| | - Lizhong Miao
- Binzhou Animal Science and Veterinary Medicine Academy, Binzhou 256600, Shandong, China
| | - Guangjun Guo
- Binzhou Animal Science and Veterinary Medicine Academy, Binzhou 256600, Shandong, China
| | - Zhiqiang Shen
- Shandong Lvdu Biological Technology Co. Ltd, Binzhou 256600, Shandong, China; Binzhou Animal Science and Veterinary Medicine Academy, Binzhou 256600, Shandong, China.
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12
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Harju N. Regulation of oxidative stress and inflammatory responses in human retinal pigment epithelial cells. Acta Ophthalmol 2022; 100 Suppl 273:3-59. [DOI: 10.1111/aos.15275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Niina Harju
- School of Pharmacy University of Eastern Finland Kuopio Finland
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13
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Dao TP, Yang Y, Presti MF, Cosgrove MS, Hopkins JB, Ma W, Loh SN, Castañeda CA. Mechanistic insights into enhancement or inhibition of phase separation by different polyubiquitin chains. EMBO Rep 2022; 23:e55056. [PMID: 35762418 PMCID: PMC9346500 DOI: 10.15252/embr.202255056] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 12/03/2022] Open
Abstract
Ubiquitin‐binding shuttle UBQLN2 mediates crosstalk between proteasomal degradation and autophagy, likely via interactions with K48‐ and K63‐linked polyubiquitin chains, respectively. UBQLN2 comprises self‐associating regions that drive its homotypic liquid–liquid phase separation (LLPS). Specific interactions between one of these regions and ubiquitin inhibit UBQLN2 LLPS. Here, we show that, unlike ubiquitin, the effects of multivalent polyubiquitin chains on UBQLN2 LLPS are highly dependent on chain types. Specifically, K11‐Ub4 and K48‐Ub4 chains generally inhibit UBQLN2 LLPS, whereas K63‐Ub4, M1‐Ub4 chains, and a designed tetrameric ubiquitin construct significantly enhance LLPS. We demonstrate that these opposing effects stem from differences in chain conformations but not in affinities between chains and UBQLN2. Chains with extended conformations and increased accessibility to the ubiquitin‐binding surface promote UBQLN2 LLPS by enabling a switch between homotypic to partially heterotypic LLPS that is driven by both UBQLN2 self‐interactions and interactions between multiple UBQLN2 units with each polyubiquitin chain. Our study provides mechanistic insights into how the structural and conformational properties of polyubiquitin chains contribute to heterotypic LLPS with ubiquitin‐binding shuttles and adaptors.
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Affiliation(s)
- Thuy P Dao
- Departments of Biology and Chemistry Syracuse University Syracuse NY USA
| | - Yiran Yang
- Department of Chemistry Syracuse University Syracuse NY USA
| | - Maria F Presti
- Department of Biochemistry and Molecular Biology SUNY Upstate Medical University Syracuse NY USA
| | - Michael S Cosgrove
- Department of Biochemistry and Molecular Biology SUNY Upstate Medical University Syracuse NY USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological Sciences Illinois Institute of Technology Chicago IL USA
| | - Weikang Ma
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological Sciences Illinois Institute of Technology Chicago IL USA
| | - Stewart N Loh
- Department of Biochemistry and Molecular Biology SUNY Upstate Medical University Syracuse NY USA
| | - Carlos A Castañeda
- Departments of Biology and Chemistry Syracuse University Syracuse NY USA
- Interdisciplinary Neuroscience Program Syracuse University Syracuse NY USA
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14
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Selective autophagy: adding precision in plant immunity. Essays Biochem 2022; 66:189-206. [PMID: 35635102 PMCID: PMC9400066 DOI: 10.1042/ebc20210063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/06/2022] [Accepted: 05/17/2022] [Indexed: 12/12/2022]
Abstract
Plant immunity is antagonized by pathogenic effectors during interactions with bacteria, viruses or oomycetes. These effectors target core plant processes to promote infection. One such core plant process is autophagy, a conserved proteolytic pathway involved in ensuring cellular homeostasis. It involves the formation of autophagosomes around proteins destined for autophagic degradation. Many cellular components from organelles, aggregates, inactive or misfolded proteins have been found to be degraded via autophagy. Increasing evidence points to a high degree of specificity during the targeting of these components, strengthening the idea of selective autophagy. Selective autophagy receptors bridge the gap between target proteins and the forming autophagosome. To achieve this, the receptors are able to recognize specifically their target proteins in a ubiquitin-dependent or -independent manner, and to bind to ATG8 via canonical or non-canonical ATG8-interacting motifs. Some receptors have also been shown to require oligomerization to achieve their function in autophagic degradation. We summarize the recent advances in the role of selective autophagy in plant immunity and highlight NBR1 as a key player. However, not many selective autophagy receptors, especially those functioning in immunity, have been characterized in plants. We propose an in silico approach to identify novel receptors, by screening the Arabidopsis proteome for proteins containing features theoretically needed for a selective autophagy receptor. To corroborate these data, the transcript levels of these proteins during immune response are also investigated using public databases. We further highlight the novel perspectives and applications introduced by immunity-related selective autophagy studies, demonstrating its importance in research.
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15
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Fleming A, Bourdenx M, Fujimaki M, Karabiyik C, Krause GJ, Lopez A, Martín-Segura A, Puri C, Scrivo A, Skidmore J, Son SM, Stamatakou E, Wrobel L, Zhu Y, Cuervo AM, Rubinsztein DC. The different autophagy degradation pathways and neurodegeneration. Neuron 2022; 110:935-966. [PMID: 35134347 PMCID: PMC8930707 DOI: 10.1016/j.neuron.2022.01.017] [Citation(s) in RCA: 171] [Impact Index Per Article: 85.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/31/2021] [Accepted: 01/11/2022] [Indexed: 12/11/2022]
Abstract
The term autophagy encompasses different pathways that route cytoplasmic material to lysosomes for degradation and includes macroautophagy, chaperone-mediated autophagy, and microautophagy. Since these pathways are crucial for degradation of aggregate-prone proteins and dysfunctional organelles such as mitochondria, they help to maintain cellular homeostasis. As post-mitotic neurons cannot dilute unwanted protein and organelle accumulation by cell division, the nervous system is particularly dependent on autophagic pathways. This dependence may be a vulnerability as people age and these processes become less effective in the brain. Here, we will review how the different autophagic pathways may protect against neurodegeneration, giving examples of both polygenic and monogenic diseases. We have considered how autophagy may have roles in normal CNS functions and the relationships between these degradative pathways and different types of programmed cell death. Finally, we will provide an overview of recently described strategies for upregulating autophagic pathways for therapeutic purposes.
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Affiliation(s)
- Angeleen Fleming
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Mathieu Bourdenx
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Motoki Fujimaki
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Cansu Karabiyik
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Gregory J Krause
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Ana Lopez
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Adrián Martín-Segura
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Claudia Puri
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Aurora Scrivo
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA
| | - John Skidmore
- The ALBORADA Drug Discovery Institute, University of Cambridge, Island Research Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0AH, UK
| | - Sung Min Son
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Eleanna Stamatakou
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Lidia Wrobel
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Ye Zhu
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Ana Maria Cuervo
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - David C Rubinsztein
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
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16
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Marshall RS, Vierstra RD. A trio of ubiquitin ligases sequentially drives ubiquitylation and autophagic degradation of dysfunctional yeast proteasomes. Cell Rep 2022; 38:110535. [PMID: 35294869 DOI: 10.1016/j.celrep.2022.110535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 12/08/2021] [Accepted: 02/25/2022] [Indexed: 12/22/2022] Open
Abstract
As central effectors of ubiquitin (Ub)-mediated proteolysis, proteasomes are regulated at multiple levels, including degradation of unwanted or dysfunctional particles via autophagy (termed proteaphagy). In yeast, inactive proteasomes are exported from the nucleus, sequestered into cytoplasmic aggresomes via the Hsp42 chaperone, extensively ubiquitylated, and then tethered to the expanding phagophore by the autophagy receptor Cue5. Here, we demonstrate the need for ubiquitylation driven by the trio of Ub ligases (E3s), San1, Rsp5, and Hul5, which together with their corresponding E2s work sequentially to promote nuclear export and Cue5 recognition. Whereas San1 functions prior to nuclear export, Rsp5 and Hul5 likely decorate aggresome-localized proteasomes in concert. Ultimately, topologically complex Ub chain(s) containing both K48 and K63 Ub-Ub linkages are assembled, mainly on the regulatory particle, to generate autophagy-competent substrates. Because San1, Rsp5, Hul5, Hsp42, and Cue5 also participate in general proteostasis, proteaphagy likely engages a fundamental mechanism for eliminating inactive/misfolded proteins.
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Affiliation(s)
- Richard S Marshall
- Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63130, USA.
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63130, USA.
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17
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Kumar R, Shroff A, Nazarko TY. Komagataella phaffii Cue5 Piggybacks on Lipid Droplets for Its Vacuolar Degradation during Stationary Phase Lipophagy. Cells 2022; 11:215. [PMID: 35053331 PMCID: PMC8774080 DOI: 10.3390/cells11020215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 02/06/2023] Open
Abstract
Recently, we developed Komagataella phaffii (formerly Pichia pastoris) as a model for lipophagy, the selective autophagy of lipid droplets (LDs). We found that lipophagy pathways induced by acute nitrogen (N) starvation and in stationary (S) phase have different molecular mechanisms. Moreover, both types of lipophagy are independent of Atg11, the scaffold protein that interacts with most autophagic receptors and, therefore, is essential for most types of selective autophagy in yeast. Since yeast aggrephagy, the selective autophagy of ubiquitinated protein aggregates, is also independent of Atg11 and utilizes the ubiquitin-binding receptor, Cue5, we studied the relationship of K. phaffii Cue5 with differentially induced LDs and lipophagy. While there was no relationship of Cue5 with LDs and lipophagy under N-starvation conditions, Cue5 accumulated on LDs in S-phase and degraded together with LDs via S-phase lipophagy. The accumulation of Cue5 on LDs and its degradation by S-phase lipophagy strongly depended on the ubiquitin-binding CUE domain and Prl1, the positive regulator of lipophagy 1. However, unlike Prl1, which is required for S-phase lipophagy, Cue5 was dispensable for it suggesting that Cue5 is rather a new substrate of this pathway. We propose that a similar mechanism (Prl1-dependent accumulation on LDs) might be employed by Prl1 to recruit another ubiquitin-binding protein that is essential for S-phase lipophagy.
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Affiliation(s)
- Ravinder Kumar
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA;
| | - Ankit Shroff
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA;
| | - Taras Y. Nazarko
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA;
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA;
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18
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Spatial control of avidity regulates initiation and progression of selective autophagy. Nat Commun 2021; 12:7194. [PMID: 34893607 PMCID: PMC8664900 DOI: 10.1038/s41467-021-27420-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 11/17/2021] [Indexed: 11/11/2022] Open
Abstract
Autophagosomes form at the endoplasmic reticulum in mammals, and between the vacuole and the endoplasmic reticulum in yeast. However, the roles of these sites and the mechanisms regulating autophagosome formation are incompletely understood. Vac8 is required for autophagy and recruits the Atg1 kinase complex to the vacuole. Here we show that Vac8 acts as a central hub to nucleate the phagophore assembly site at the vacuolar membrane during selective autophagy. Vac8 directly recruits the cargo complex via the Atg11 scaffold. In addition, Vac8 recruits the phosphatidylinositol 3-kinase complex independently of autophagy. Cargo-dependent clustering and Vac8-dependent sequestering of these early autophagy factors, along with local Atg1 activation, promote phagophore assembly site assembly at the vacuole. Importantly, ectopic Vac8 redirects autophagosome formation to the nuclear membrane, indicating that the vacuolar membrane is not specifically required. We propose that multiple avidity-driven interactions drive the initiation and progression of selective autophagy. The molecular principles governing the initiation of autophagosome formation are not clearly understood. Here we show that the vacuolar protein Vac8 coordinates this process by promoting an avidity-driven assembly of several autophagy factors.
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19
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Sarkar A, Nazir A. Carrying Excess Baggage Can Slowdown Life: Protein Clearance Machineries That Go Awry During Aging and the Relevance of Maintaining Them. Mol Neurobiol 2021; 59:821-840. [PMID: 34792731 DOI: 10.1007/s12035-021-02640-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/05/2021] [Indexed: 01/07/2023]
Abstract
Cellular homeostasis is maintained by rapid and systematic cleansing of aberrant and aggregated proteins within cells. Neurodegenerative diseases (NDs) especially Parkinson's and Alzheimer's disease are known to be associated with multiple factors, most important being impaired clearance of aggregates, resulting in the accumulation of specific aggregated protein in the brain. Protein quality control (PQC) of proteostasis network comprises proteolytic machineries and chaperones along with their regulators to ensure precise operation and maintenance of proteostasis. Such regulatory factors coordinate among each other multiple functional aspects related to proteins, including their synthesis, folding, transport, and degradation. During aging due to inevitable endogenous and external stresses, sustaining a proteome balance is a challenging task. Such stresses decline the capacity of the proteostasis network compromising the proteome integrity, affecting the fundamental physiological processes including reproductive fitness of the organism. This review focuses on highlighting proteome-wide changes during aging and the strategies for proteostasis improvements. The possibility of augmenting the proteostasis network either via genetic or pharmacological interventions may be a promising strategy towards delaying age-associated pathological consequences due to proteome disbalance, thus promoting healthy aging and prolonged longevity.
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Affiliation(s)
- Arunabh Sarkar
- Division of Neuroscience and Ageing Biology, CSIR-Central Drug Research Institute, Lucknow, UP, 226031, India
| | - Aamir Nazir
- Division of Neuroscience and Ageing Biology, CSIR-Central Drug Research Institute, Lucknow, UP, 226031, India.
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20
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The Cytotoxicity and Clearance of Mutant Huntingtin and Other Misfolded Proteins. Cells 2021; 10:cells10112835. [PMID: 34831058 PMCID: PMC8616338 DOI: 10.3390/cells10112835] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 02/07/2023] Open
Abstract
Protein misfolding and aggregation are implicated in many neurodegenerative diseases. One of these diseases is Huntington's, which is caused by increased glutamine-encoding trinucleotide repeats within the Huntingtin gene. Like other misfolded proteins, mutated Huntingtin proteins with polyglutamine expansions are prone to aggregation. Misfolded proteins exist as soluble monomers, small aggregates, or as large insoluble inclusion bodies. Misfolded protein aggregates are believed to be cytotoxic by stressing the protein degradation machinery, disrupting membrane structure, or sequestering other proteins. We recently showed that expression of misfolded proteins lowers cellular free ubiquitin levels, which compromises the protein degradation machinery. Therefore, the efficient degradation of misfolded proteins is critical to preserve cell health. Cells employ two major mechanisms to degrade misfolded proteins. The first is the ubiquitin-proteasome system (UPS), which ubiquitinates and degrades misfolded proteins with the assistance of segregase Cdc48/p97. The UPS pathway is mainly responsible for the clearance of misfolded proteins present as monomers or smaller aggregates. The second pathway is macroautophagy/autophagy, in which protein aggregates or inclusion bodies are recruited into an autophagosome before transport to the vacuole/lysosome for degradation. This review is focused on the current understanding of the cytotoxicity of misfolded proteins as well as their clearance pathways, with a particular emphasis on mutant Huntingtin.
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21
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Clavel M, Dagdas Y. Proteasome and selective autophagy: Brothers-in-arms for organelle quality control. CURRENT OPINION IN PLANT BIOLOGY 2021; 63:102106. [PMID: 34487948 DOI: 10.1016/j.pbi.2021.102106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/08/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
Maintaining the integrity of organelles despite the cellular disturbances that arise during stress is essential for life. To ensure organelle proteostasis (protein homeostasis), plants have evolved multitiered quality control mechanisms that work together to repair or recycle the damaged organelles. Despite recent advances, our understanding of plant organelle quality control mechanisms is far from complete. Especially, the crosstalk between different quality control pathways remains elusive. Here, we highlight recent advances on organelle quality control, focusing on the targeted protein degradation pathways that maintain the homeostasis of the endoplasmic reticulum (ER), chloroplast, and mitochondria. We discuss how plant cells decide to employ different degradation pathways and propose tools that could be used to discover the missing components in organelle quality control.
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Affiliation(s)
- Marion Clavel
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria.
| | - Yasin Dagdas
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria.
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22
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Chen W, Shen T, Wang L, Lu K. Oligomerization of Selective Autophagy Receptors for the Targeting and Degradation of Protein Aggregates. Cells 2021; 10:cells10081989. [PMID: 34440758 PMCID: PMC8394947 DOI: 10.3390/cells10081989] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 02/05/2023] Open
Abstract
The selective targeting and disposal of solid protein aggregates are essential for cells to maintain protein homoeostasis. Autophagy receptors including p62, NBR1, Cue5/TOLLIP (CUET), and Tax1-binding protein 1 (TAX1BP1) proteins function in selective autophagy by targeting ubiquitinated aggregates through ubiquitin-binding domains. Here, we summarize previous beliefs and recent findings on selective receptors in aggregate autophagy. Since there are many reviews on selective autophagy receptors, we focus on their oligomerization, which enables receptors to function as pathway determinants and promotes phase separation.
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Affiliation(s)
- Wenjun Chen
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
- Department of Neurology, Shanxi Provincial People’s Hospital, Taiyuan 030012, China
| | - Tianyun Shen
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
| | - Lijun Wang
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
| | - Kefeng Lu
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
- Correspondence:
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23
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Sun-Wang JL, Yarritu-Gallego A, Ivanova S, Zorzano A. The ubiquitin-proteasome system and autophagy: self-digestion for metabolic health. Trends Endocrinol Metab 2021; 32:594-608. [PMID: 34034951 DOI: 10.1016/j.tem.2021.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 01/02/2023]
Abstract
Type 2 diabetes mellitus (T2DM) is a global health challenge. Therefore, understanding the molecular mechanisms underlying the pathophysiology of T2DM is key to improving current therapies. Loss of protein homeostasis leads to the accumulation of damaged proteins in cells, which results in tissue dysfunction. The elimination of damaged proteins occurs through the ubiquitin-proteasome system (UPS) and autophagy. In this review, we describe the mutual regulation between the UPS and autophagy and the involvement of these two proteolytic systems in metabolic dysregulation, insulin resistance, and T2DM. We propose that alterations in the UPS or autophagy contribute to triggering insulin resistance and the development of T2DM. In addition, these two pathways emerge as promising therapeutic targets for improving insulin resistance.
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Affiliation(s)
- Jia Liang Sun-Wang
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain.
| | - Alex Yarritu-Gallego
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, Berlin, Germany; Experimental and Clinical Research Center, a Cooperation of Charité-Universitätsmedizin Berlin and Max Delbruck Center for Molecular Medicine, Berlin, Germany
| | - Saška Ivanova
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain.
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24
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Lei L, Wu Z, Winklhofer KF. Protein quality control by the proteasome and autophagy: A regulatory role of ubiquitin and liquid-liquid phase separation. Matrix Biol 2021; 100-101:9-22. [DOI: 10.1016/j.matbio.2020.11.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 12/14/2022]
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25
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UBQLN2-HSP70 axis reduces poly-Gly-Ala aggregates and alleviates behavioral defects in the C9ORF72 animal model. Neuron 2021; 109:1949-1962.e6. [PMID: 33991504 DOI: 10.1016/j.neuron.2021.04.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 01/09/2021] [Accepted: 04/23/2021] [Indexed: 12/12/2022]
Abstract
Expansion of a hexanucleotide repeat GGGGCC (G4C2) in the intron of the C9ORF72 gene is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9-ALS/FTD). Transcripts carrying G4C2 repeat expansions generate neurotoxic dipeptide repeat (DPR) proteins, including poly-Gly-Ala (poly-GA), which tends to form protein aggregates. Here, we demonstrate that UBQLN2, another ALS/FTD risk factor, is recruited to reduce poly-GA aggregates and alleviate poly-GA-induced neurotoxicity. UBQLN2 could recognize HSP70 ubiquitination, which facilitates the UBQLN2-HSP70-GA complex formation and promotes poly-GA degradation. ALS/FTD-related UBQLN2 mutants fail to bind HSP70 and clear poly-GA aggregates. Disruption of the interaction between UBQLN2 and HSP70 inhibits poly-GA aggregation in C9-ALS/FTD iPSC-derived neurons. Finally, enhancing HSP70 by the chemical compound 17AAG at the adult stage mitigates behavioral defects in poly-GA animals. Our findings suggest a critical role of the UBQLN2-HSP70 axis in protein aggregate clearance in C9-ALS/FTD.
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Malcova I, Senohrabkova L, Novakova L, Hasek J. eIF3a Destabilization and TDP-43 Alter Dynamics of Heat-Induced Stress Granules. Int J Mol Sci 2021; 22:ijms22105164. [PMID: 34068231 PMCID: PMC8153170 DOI: 10.3390/ijms22105164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/04/2021] [Accepted: 05/08/2021] [Indexed: 12/17/2022] Open
Abstract
Stress granules (SGs) are membrane-less assemblies arising upon various stresses in eukaryotic cells. They sequester mRNAs and proteins from stressful conditions and modulate gene expression to enable cells to resume translation and growth after stress relief. SGs containing the translation initiation factor eIF3a/Rpg1 arise in yeast cells upon robust heat shock (HS) at 46 °C only. We demonstrate that the destabilization of Rpg1 within the PCI domain in the Rpg1-3 variant leads to SGs assembly already at moderate HS at 42 °C. These are bona fide SGs arising upon translation arrest containing mRNAs, which are components of the translation machinery, and associating with P-bodies. HS SGs associate with endoplasmatic reticulum and mitochondria and their contact sites ERMES. Although Rpg1-3-labeled SGs arise at a lower temperature, their disassembly is delayed after HS at 46 °C. Remarkably, the delayed disassembly of HS SGs after the robust HS is reversed by TDP-43, which is a human protein connected with amyotrophic lateral sclerosis. TDP-43 colocalizes with HS SGs in yeast cells and facilitates cell regrowth after the stress relief. Based on our results, we propose yeast HS SGs labeled by Rpg1 and its variants as a novel model system to study functions of TDP-43 in stress granules disassembly.
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Affiliation(s)
- Ivana Malcova
- Institute of Microbiology, Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic; (L.S.); (L.N.); (J.H.)
- Correspondence: ; Tel.: +420-241062769
| | - Lenka Senohrabkova
- Institute of Microbiology, Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic; (L.S.); (L.N.); (J.H.)
- First Faculty of Medicine, Charles University, Katerinska 42, 12108 Prague, Czech Republic
| | - Lenka Novakova
- Institute of Microbiology, Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic; (L.S.); (L.N.); (J.H.)
| | - Jiri Hasek
- Institute of Microbiology, Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic; (L.S.); (L.N.); (J.H.)
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Herpesvirus Regulation of Selective Autophagy. Viruses 2021; 13:v13050820. [PMID: 34062931 PMCID: PMC8147283 DOI: 10.3390/v13050820] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 12/18/2022] Open
Abstract
Selective autophagy has emerged as a key mechanism of quality and quantity control responsible for the autophagic degradation of specific subcellular organelles and materials. In addition, a specific type of selective autophagy (xenophagy) is also activated as a line of defense against invading intracellular pathogens, such as viruses. However, viruses have evolved strategies to counteract the host’s antiviral defense and even to activate some proviral types of selective autophagy, such as mitophagy, for their successful infection and replication. This review discusses the current knowledge on the regulation of selective autophagy by human herpesviruses.
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28
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Yoon MJ, Choi B, Kim EJ, Ohk J, Yang C, Choi YG, Lee J, Kang C, Song HK, Kim YK, Woo JS, Cho Y, Choi EJ, Jung H, Kim C. UXT chaperone prevents proteotoxicity by acting as an autophagy adaptor for p62-dependent aggrephagy. Nat Commun 2021; 12:1955. [PMID: 33782410 PMCID: PMC8007730 DOI: 10.1038/s41467-021-22252-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 03/02/2021] [Indexed: 02/01/2023] Open
Abstract
p62/SQSTM1 is known to act as a key mediator in the selective autophagy of protein aggregates, or aggrephagy, by steering ubiquitinated protein aggregates towards the autophagy pathway. Here, we use a yeast two-hybrid screen to identify the prefoldin-like chaperone UXT as an interacting protein of p62. We show that UXT can bind to protein aggregates as well as the LB domain of p62, and, possibly by forming an oligomer, increase p62 clustering for its efficient targeting to protein aggregates, thereby promoting the formation of the p62 body and clearance of its cargo via autophagy. We also find that ectopic expression of human UXT delays SOD1(A4V)-induced degeneration of motor neurons in a Xenopus model system, and that specific disruption of the interaction between UXT and p62 suppresses UXT-mediated protection. Together, these results indicate that UXT functions as an autophagy adaptor of p62-dependent aggrephagy. Furthermore, our study illustrates a cooperative relationship between molecular chaperones and the aggrephagy machinery that efficiently removes misfolded protein aggregates.
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Affiliation(s)
- Min Ji Yoon
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Boyoon Choi
- Department of Anatomy, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Eun Jin Kim
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Jiyeon Ohk
- Department of Anatomy, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Chansik Yang
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Yeon-Gil Choi
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Jinyoung Lee
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Chanhee Kang
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hyun Kyu Song
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Yoon Ki Kim
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Jae-Sung Woo
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Yongcheol Cho
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Eui-Ju Choi
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Hosung Jung
- Department of Anatomy, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea.
| | - Chungho Kim
- Department of Life Sciences, Korea University, Seoul, Republic of Korea.
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Maiuolo J, Gliozzi M, Musolino V, Carresi C, Scarano F, Nucera S, Scicchitano M, Bosco F, Ruga S, Zito MC, Macri R, Bulotta R, Muscoli C, Mollace V. From Metabolic Syndrome to Neurological Diseases: Role of Autophagy. Front Cell Dev Biol 2021; 9:651021. [PMID: 33816502 PMCID: PMC8017166 DOI: 10.3389/fcell.2021.651021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/26/2021] [Indexed: 12/17/2022] Open
Abstract
Metabolic syndrome is not a single pathology, but a constellation of cardiovascular disease risk factors including: central and abdominal obesity, systemic hypertension, insulin resistance (or type 2 diabetes mellitus), and atherogenic dyslipidemia. The global incidence of Metabolic syndrome is estimated to be about one quarter of the world population; for this reason, it would be desirable to better understand the underlying mechanisms involved in order to develop treatments that can reduce or eliminate the damage caused. The effects of Metabolic syndrome are multiple and wide ranging; some of which have an impact on the central nervous system and cause neurological and neurodegenerative diseases. Autophagy is a catabolic intracellular process, essential for the recycling of cytoplasmic materials and for the degradation of damaged cellular organelle. Therefore, autophagy is primarily a cytoprotective mechanism; even if excessive cellular degradation can be detrimental. To date, it is known that systemic autophagic insufficiency is able to cause metabolic balance deterioration and facilitate the onset of metabolic syndrome. This review aims to highlight the current state of knowledge regarding the connection between metabolic syndrome and the onset of several neurological diseases related to it. Furthermore, since autophagy has been found to be of particular importance in metabolic disorders, the probable involvement of this degradative process is assumed to be responsible for the attenuation of neurological disorders resulting from metabolic syndrome.
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Affiliation(s)
- Jessica Maiuolo
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Micaela Gliozzi
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Vincenzo Musolino
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Cristina Carresi
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Federica Scarano
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Saverio Nucera
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Miriam Scicchitano
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Francesca Bosco
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Stefano Ruga
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Maria Caterina Zito
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Roberta Macri
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Rosamaria Bulotta
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Carolina Muscoli
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
- IRCCS San Raffaele, Rome, Italy
| | - Vincenzo Mollace
- IRC-FSH Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
- IRCCS San Raffaele, Rome, Italy
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30
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Chen YH, Huang TY, Lin YT, Lin SY, Li WH, Hsiao HJ, Yan RL, Tang HW, Shen ZQ, Chen GC, Wu KP, Tsai TF, Chen RH. VPS34 K29/K48 branched ubiquitination governed by UBE3C and TRABID regulates autophagy, proteostasis and liver metabolism. Nat Commun 2021; 12:1322. [PMID: 33637724 PMCID: PMC7910580 DOI: 10.1038/s41467-021-21715-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 02/05/2021] [Indexed: 12/15/2022] Open
Abstract
The ubiquitin-proteasome system (UPS) and autophagy are two major quality control processes whose impairment is linked to a wide variety of diseases. The coordination between UPS and autophagy remains incompletely understood. Here, we show that ubiquitin ligase UBE3C and deubiquitinating enzyme TRABID reciprocally regulate K29/K48-branched ubiquitination of VPS34. We find that this ubiquitination enhances the binding of VPS34 to proteasomes for degradation, thereby suppressing autophagosome formation and maturation. Under ER and proteotoxic stresses, UBE3C recruitment to phagophores is compromised with a concomitant increase of its association with proteasomes. This switch attenuates the action of UBE3C on VPS34, thereby elevating autophagy activity to facilitate proteostasis, ER quality control and cell survival. Specifically in the liver, we show that TRABID-mediated VPS34 stabilization is critical for lipid metabolism and is downregulated during the pathogenesis of steatosis. This study identifies a ubiquitination type on VPS34 and elucidates its cellular fate and physiological functions in proteostasis and liver metabolism.
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Affiliation(s)
- Yu-Hsuan Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Tzu-Yu Huang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Yu-Tung Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Shu-Yu Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Wen-Hsin Li
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsiang-Jung Hsiao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ruei-Liang Yan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hong-Wen Tang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Zhao-Qing Shen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Guang-Chao Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Kuen-Phon Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Ting-Fen Tsai
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Ruey-Hwa Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan.
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
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31
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Human TRIM5α: Autophagy Connects Cell-Intrinsic HIV-1 Restriction and Innate Immune Sensor Functioning. Viruses 2021; 13:v13020320. [PMID: 33669846 PMCID: PMC7923229 DOI: 10.3390/v13020320] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/12/2021] [Accepted: 02/13/2021] [Indexed: 12/12/2022] Open
Abstract
Human immunodeficiency virus-1 (HIV-1) persists as a global health concern, with an incidence rate of approximately 2 million, and estimated global prevalence of over 35 million. Combination antiretroviral treatment is highly effective, but HIV-1 patients that have been treated still suffer from chronic inflammation and residual viral replication. It is therefore paramount to identify therapeutically efficacious strategies to eradicate viral reservoirs and ultimately develop a cure for HIV-1. It has been long accepted that the restriction factor tripartite motif protein 5 isoform alpha (TRIM5α) restricts HIV-1 infection in a species-specific manner, with rhesus macaque TRIM5α strongly restricting HIV-1, and human TRIM5α having a minimal restriction capacity. However, several recent studies underscore human TRIM5α as a cell-dependent HIV-1 restriction factor. Here, we present an overview of the latest research on human TRIM5α and propose a novel conceptualization of TRIM5α as a restriction factor with a varied portfolio of antiviral functions, including mediating HIV-1 degradation through autophagy- and proteasome-mediated mechanisms, and acting as a viral sensor and effector of antiviral signaling. We have also expanded on the protective antiviral roles of autophagy and outline the therapeutic potential of autophagy modulation to intervene in chronic HIV-1 infection.
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32
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Casey GR, Zhou X, Lesiak L, Xu B, Fang Y, Becker DF, Stains CI. An Evolutionary Strategy for Identification of Higher Order, Green Fluorescent Host-Guest Pairs Compatible with Living Systems. Chemistry 2020; 26:16721-16726. [PMID: 32725914 DOI: 10.1002/chem.202002423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 07/26/2020] [Indexed: 11/09/2022]
Abstract
Engineered miniprotein host-small-molecule guest pairs could be utilized to design new processes within cells as well as investigate fundamental aspects of cell signaling mechanisms. However, the development of host-guest pairs capable of functioning in living systems has proven challenging. Moreover, few examples of host-guest pairs with stoichiometries other than 2:1 exist, significantly hindering the ability to study the influence of oligomerization state on signaling fidelity. Herein, we present an approach to identify host-guest systems for relatively small green fluorescent guests by incorporation into cyclic peptides. The optimal host-guest pair produced a 10-fold increase in green fluorescence signal upon binding. Biophysical characterization clearly demonstrated higher order supramolecular assembly, which could be visualized on the surface of living yeast cells using a turn-on fluorescence readout. This work further defines evolutionary design principles to afford host-guest pairs with stoichiometries other than 2:1 and enables the identification of spectrally orthogonal host-guest pairs.
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Affiliation(s)
- Garrett R Casey
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.,Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO, 63701, USA
| | - Xinqi Zhou
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Lauren Lesiak
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Bi Xu
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Yuan Fang
- Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, USA
| | - Donald F Becker
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Cliff I Stains
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.,Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, USA.,Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.,Cancer Genes and Molecular Regulation Program, Fred & Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA.,University of Virginia Cancer Center, University of Virginia, Charlottesville, VA, 22904, USA
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33
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Weng FL, He L. Disrupted ubiquitin proteasome system underlying tau accumulation in Alzheimer's disease. Neurobiol Aging 2020; 99:79-85. [PMID: 33422896 DOI: 10.1016/j.neurobiolaging.2020.11.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 11/12/2020] [Accepted: 11/22/2020] [Indexed: 01/02/2023]
Abstract
Accumulation of phosphorylated tau (p-tau) has long been an underappreciated hallmark of Alzheimer's disease. Tau is one of the major components of microtubule networks in neurons, and its abnormal phosphorylation and aggregation are closely related to the impairment of axonal transport. Abnormalities in axonal transport can impede autophagy in neurons, interrupting the autophagic clearance of amyloid beta. The ubiquitin proteasome system (UPS) maintains intracellular proteostasis by degrading abnormal or redundant proteins. Ever-mounting evidence suggests that UPS deficits contribute to p-tau accumulation. And targeting UPS attenuates tau pathology. This review endeavors to exam the potential role of UPS in p-tau aggregation, and how pathogenic tau may inflict other abnormalities such as amyloid beta accumulation in Alzheimer's disease.
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Affiliation(s)
- Fang-Lin Weng
- Department of Pharmacology, China Pharmaceutical University, Nanjing, People's Republic of China
| | - Ling He
- Department of Pharmacology, China Pharmaceutical University, Nanjing, People's Republic of China.
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34
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The dialogue between the ubiquitin-proteasome system and autophagy: Implications in ageing. Ageing Res Rev 2020; 64:101203. [PMID: 33130248 DOI: 10.1016/j.arr.2020.101203] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/09/2020] [Accepted: 10/25/2020] [Indexed: 02/06/2023]
Abstract
Dysregulated proteostasis is one of the hallmarks of ageing. Damaged proteins may impair cellular function and their accumulation may lead to tissue dysfunction and disease. This is why protective mechanisms to safeguard the cell proteome have evolved. These mechanisms consist of cellular machineries involved in protein quality control, including regulators of protein translation, folding, trafficking and degradation. In eukaryotic cells, protein degradation occurs via two main pathways: the ubiquitin-proteasome system (UPS) and the autophagy-lysosome pathway. Although distinct pathways, they are not isolated systems and have a complementary nature, as evidenced by recent studies. These findings raise the question of how autophagy and the proteasome crosstalk. In this review we address how the two degradation pathways impact each other, thereby adding a new layer of regulation to protein degradation. We also analyze the implications of the UPS and autophagy in ageing.
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35
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Johnston HE, Samant RS. Alternative systems for misfolded protein clearance: life beyond the proteasome. FEBS J 2020; 288:4464-4487. [PMID: 33135311 DOI: 10.1111/febs.15617] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/15/2020] [Accepted: 10/30/2020] [Indexed: 12/18/2022]
Abstract
Protein misfolding is a major driver of ageing-associated frailty and disease pathology. Although all cells possess multiple, well-characterised protein quality control systems to mitigate the toxicity of misfolded proteins, how they are integrated to maintain protein homeostasis ('proteostasis') in health-and how their disintegration contributes to disease-is still an exciting and fast-paced area of research. Under physiological conditions, the predominant route for misfolded protein clearance involves ubiquitylation and proteasome-mediated degradation. When the capacity of this route is overwhelmed-as happens during conditions of acute environmental stress, or chronic ageing-related decline-alternative routes for protein quality control are activated. In this review, we summarise our current understanding of how proteasome-targeted misfolded proteins are retrafficked to alternative protein quality control routes such as juxta-nuclear sequestration and selective autophagy when the ubiquitin-proteasome system is compromised. We also discuss the molecular determinants of these alternative protein quality control systems, attempt to clarify distinctions between various cytoplasmic spatial quality control inclusion bodies (e.g., Q-bodies, p62 bodies, JUNQ, aggresomes, and aggresome-like induced structures 'ALIS'), and speculate on emerging concepts in the field that we hope will spur future research-with the potential to benefit the rational development of healthy ageing strategies.
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Affiliation(s)
| | - Rahul S Samant
- Signalling Programme, The Babraham Institute, Cambridge, UK
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36
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Dao TP, Castañeda CA. Ubiquitin-Modulated Phase Separation of Shuttle Proteins: Does Condensate Formation Promote Protein Degradation? Bioessays 2020; 42:e2000036. [PMID: 32881044 PMCID: PMC7737676 DOI: 10.1002/bies.202000036] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/29/2020] [Indexed: 12/14/2022]
Abstract
Liquid-liquid phase separation (LLPS) has recently emerged as a possible mechanism that enables ubiquitin-binding shuttle proteins to facilitate the degradation of ubiquitinated substrates via distinct protein quality control (PQC) pathways. Shuttle protein LLPS is modulated by multivalent interactions among their various domains as well as heterotypic interactions with polyubiquitin chains. Here, the properties of three different shuttle proteins (hHR23B, p62, and UBQLN2) are closely examined, unifying principles for the molecular determinants of their LLPS are identified, and how LLPS is connected to their functions is discussed. Evidence supporting LLPS of other shuttle proteins is also found. In this review, it is proposed that shuttle protein LLPS leads to spatiotemporal regulation of PQC activities by mediating the recruitment of PQC machinery (including proteasomes or autophagic components) to biomolecular condensates, assembly/disassembly of condensates, selective enrichment of client proteins, and extraction of ubiquitinated proteins from condensates in cells.
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Affiliation(s)
- Thuy P Dao
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY, 13244, USA
| | - Carlos A Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY, 13244, USA
- Bioinspired Institute, Syracuse University, Syracuse, NY, 13244, USA
- Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, NY, 13244, USA
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37
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Zheng T, Yang Y, Castañeda CA. Structure, dynamics and functions of UBQLNs: at the crossroads of protein quality control machinery. Biochem J 2020; 477:3471-3497. [PMID: 32965492 PMCID: PMC7737201 DOI: 10.1042/bcj20190497] [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: 06/30/2020] [Revised: 08/23/2020] [Accepted: 08/26/2020] [Indexed: 12/12/2022]
Abstract
Cells rely on protein homeostasis to maintain proper biological functions. Dysregulation of protein homeostasis contributes to the pathogenesis of many neurodegenerative diseases and cancers. Ubiquilins (UBQLNs) are versatile proteins that engage with many components of protein quality control (PQC) machinery in cells. Disease-linked mutations of UBQLNs are most commonly associated with amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neurodegenerative disorders. UBQLNs play well-established roles in PQC processes, including facilitating degradation of substrates through the ubiquitin-proteasome system (UPS), autophagy, and endoplasmic-reticulum-associated protein degradation (ERAD) pathways. In addition, UBQLNs engage with chaperones to sequester, degrade, or assist repair of misfolded client proteins. Furthermore, UBQLNs regulate DNA damage repair mechanisms, interact with RNA-binding proteins (RBPs), and engage with cytoskeletal elements to regulate cell differentiation and development. Important to the myriad functions of UBQLNs are its multidomain architecture and ability to self-associate. UBQLNs are linked to numerous types of cellular puncta, including stress-induced biomolecular condensates, autophagosomes, aggresomes, and aggregates. In this review, we focus on deciphering how UBQLNs function on a molecular level. We examine the properties of oligomerization-driven interactions among the structured and intrinsically disordered segments of UBQLNs. These interactions, together with the knowledge from studies of disease-linked mutations, provide significant insights to UBQLN structure, dynamics and function.
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Affiliation(s)
- Tongyin Zheng
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
| | - Yiran Yang
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
| | - Carlos A. Castañeda
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
- Bioinspired Institute, and the Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, NY 13244, U.S.A
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38
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The Roles of Ubiquitin in Mediating Autophagy. Cells 2020; 9:cells9092025. [PMID: 32887506 PMCID: PMC7564124 DOI: 10.3390/cells9092025] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/25/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022] Open
Abstract
Ubiquitination, the post-translational modification essential for various intracellular processes, is implicated in multiple aspects of autophagy, the major lysosome/vacuole-dependent degradation pathway. The autophagy machinery adopted the structural architecture of ubiquitin and employs two ubiquitin-like protein conjugation systems for autophagosome biogenesis. Ubiquitin chains that are attached as labels to protein aggregates or subcellular organelles confer selectivity, allowing autophagy receptors to simultaneously bind ubiquitinated cargos and autophagy-specific ubiquitin-like modifiers (Atg8-family proteins). Moreover, there is tremendous crosstalk between autophagy and the ubiquitin-proteasome system. Ubiquitination of autophagy-related proteins or regulatory components plays significant roles in the precise control of the autophagy pathway. In this review, we summarize and discuss the molecular mechanisms and functions of ubiquitin and ubiquitination, in the process and regulation of autophagy.
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39
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Kumar D, Ambasta RK, Kumar P. Ubiquitin biology in neurodegenerative disorders: From impairment to therapeutic strategies. Ageing Res Rev 2020; 61:101078. [PMID: 32407951 DOI: 10.1016/j.arr.2020.101078] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 03/24/2020] [Accepted: 04/22/2020] [Indexed: 12/13/2022]
Abstract
The abnormal accumulation of neurotoxic proteins is the typical hallmark of various age-related neurodegenerative disorders (NDDs), including Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis and Multiple sclerosis. The anomalous proteins, such as Aβ, Tau in Alzheimer's disease and α-synuclein in Parkinson's disease, perturb the neuronal physiology and cellular homeostasis in the brain thereby affecting the millions of human lives across the globe. Here, ubiquitin proteasome system (UPS) plays a decisive role in clearing the toxic metabolites in cells, where any aberrancy is widely reported to exaggerate the neurodegenerative pathologies. In spite of well-advancement in the ubiquitination research, their molecular markers and mechanisms for target-specific protein ubiquitination and clearance remained elusive. Therefore, this review substantiates the role of UPS in the brain signaling and neuronal physiology with their mechanistic role in the NDD's specific pathogenic protein clearance. Moreover, current and future promising therapies are discussed to target UPS-mediated neurodegeneration for better public health.
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40
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Mitochondrial dysfunction generates aggregates that resist lysosomal degradation in human breast cancer cells. Cell Death Dis 2020; 11:460. [PMID: 32541677 PMCID: PMC7296005 DOI: 10.1038/s41419-020-2658-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 12/14/2022]
Abstract
Disrupting functional protein homeostasis is an established therapeutic strategy for certain tumors. Ongoing studies are evaluating autophagy inhibition for overcoming chemotherapeutic resistance to such therapies by neutralizing lysosomal pH. New and sensitive methods to monitor autophagy in patients are needed to improve trial design and interpretation. We report that mitochondrial-damaged breast cancer cells and rat breast tumors accumulate p53-positive protein aggregates that resist lysosomal degradation. These aggregates were localized to enzymatically-active autolysosomes that were degrading autophagosomes and the autophagic receptor proteins TAX1BP1 and NDP52. NDP52 was identified to associate with aggregated proteins and knocking down NDP52 led to the accumulation of protein aggregates. TAX1BP1 was identified to partly localize with aggregates, and knocking down TAX1BP1 enhanced aggregate formation, suppressed autophagy, impaired NDP52 autophagic degradation and induced cell death. We propose that quantifying aggregates and autophagic receptors are two potential methods to evaluate autophagy and lysosomal degradation, as confirmed using primary human tumor samples. Collectively, this report establishes protein aggregates and autophagy receptors, TAX1BP1 and NDP52, as potential endpoints for monitoring autophagy during drug development and clinical studies.
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41
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Zhang L, Wang F, Li Q, Wang L, Fan C, Li J, Zhu Y. Classifying Cell Types with DNA-Encoded Ligand-Receptor Interactions on the Cell Membrane. NANO LETTERS 2020; 20:3521-3527. [PMID: 32223268 DOI: 10.1021/acs.nanolett.0c00445] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Clustering, endocytosis, and intracellular transport of molecules on the cell membrane are critically dependent on the type of cells. However, the membrane-associated redistribution of molecules has not been exploited to realize cell classification for diagnostic purposes. Here, we develop a set of DNA-encoded artificial receptors and ligands to monitor the cell membrane redistribution. In this system, a cholesterol-modified single-stranded DNA strand serves as the receptor localized on the membrane, and a tetrahedral DNA framework (TDF) nanostructure with a complementary overhang serves as the ligand. The DNA-encoded receptor-ligand interaction is highly orthogonal, mimicking the dynamics of natural receptors and ligands on cells. We demonstrate that the dynamics of membrane redistribution can be resolved by the dual-color fluorescent patterns of the receptor-ligand interactions in a single image, which can be exploited to classify cell lines with high fidelity. This DNA-encoded method thus holds great promise for cell typing and diagnosis.
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Affiliation(s)
- Luhao Zhang
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fei Wang
- Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Institute of Molecular Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200024, China
| | - Qian Li
- Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Institute of Molecular Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200024, China
| | - Lihua Wang
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- Bioimaging Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Chunhai Fan
- Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Institute of Molecular Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200024, China
| | - Jiang Li
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- Bioimaging Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Ying Zhu
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- Bioimaging Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
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42
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Ravanelli S, den Brave F, Hoppe T. Mitochondrial Quality Control Governed by Ubiquitin. Front Cell Dev Biol 2020; 8:270. [PMID: 32391359 PMCID: PMC7193050 DOI: 10.3389/fcell.2020.00270] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/30/2020] [Indexed: 12/15/2022] Open
Abstract
Mitochondria are essential organelles important for energy production, proliferation, and cell death. Biogenesis, homeostasis, and degradation of this organelle are tightly controlled to match cellular needs and counteract chronic stress conditions. Despite providing their own DNA, the vast majority of mitochondrial proteins are encoded in the nucleus, synthesized by cytosolic ribosomes, and subsequently imported into different mitochondrial compartments. The integrity of the mitochondrial proteome is permanently challenged by defects in folding, transport, and turnover of mitochondrial proteins. Therefore, damaged proteins are constantly sequestered from the outer mitochondrial membrane and targeted for proteasomal degradation in the cytosol via mitochondrial-associated degradation (MAD). Recent studies identified specialized quality control mechanisms important to decrease mislocalized proteins, which affect the mitochondrial import machinery. Interestingly, central factors of these ubiquitin-dependent pathways are shared with the ER-associated degradation (ERAD) machinery, indicating close collaboration between both tubular organelles. Here, we summarize recently described cellular stress response mechanisms, which are triggered by defects in mitochondrial protein import and quality control. Moreover, we discuss how ubiquitin-dependent degradation is integrated with cytosolic stress responses, particularly focused on the crosstalk between MAD and ERAD.
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Affiliation(s)
- Sonia Ravanelli
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Fabian den Brave
- Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
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43
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Joshi V, Upadhyay A, Prajapati VK, Mishra A. How autophagy can restore proteostasis defects in multiple diseases? Med Res Rev 2020; 40:1385-1439. [PMID: 32043639 DOI: 10.1002/med.21662] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 01/03/2020] [Accepted: 01/28/2020] [Indexed: 12/12/2022]
Abstract
Cellular evolution develops several conserved mechanisms by which cells can tolerate various difficult conditions and overall maintain homeostasis. Autophagy is a well-developed and evolutionarily conserved mechanism of catabolism, which endorses the degradation of foreign and endogenous materials via autolysosome. To decrease the burden of the ubiquitin-proteasome system (UPS), autophagy also promotes the selective degradation of proteins in a tightly regulated way to improve the physiological balance of cellular proteostasis that may get perturbed due to the accumulation of misfolded proteins. However, the diverse as well as selective clearance of unwanted materials and regulations of several cellular mechanisms via autophagy is still a critical mystery. Also, the failure of autophagy causes an increase in the accumulation of harmful protein aggregates that may lead to neurodegeneration. Therefore, it is necessary to address this multifactorial threat for in-depth research and develop more effective therapeutic strategies against lethal autophagy alterations. In this paper, we discuss the most relevant and recent reports on autophagy modulations and their impact on neurodegeneration and other complex disorders. We have summarized various pharmacological findings linked with the induction and suppression of autophagy mechanism and their promising preclinical and clinical applications to provide therapeutic solutions against neurodegeneration. The conclusion, key questions, and future prospectives sections summarize fundamental challenges and their possible feasible solutions linked with autophagy mechanism to potentially design an impactful therapeutic niche to treat neurodegenerative diseases and imperfect aging.
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Affiliation(s)
- Vibhuti Joshi
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
| | - Arun Upadhyay
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
| | - Vijay K Prajapati
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Ajmer, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
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44
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Fan S, Wu K, Luo C, Li X, Zhao M, Song D, Ma S, Zhu E, Chen Y, Ding H, Yi L, Li J, Zhao M, Chen J. Dual NDP52 Function in Persistent CSFV Infection. Front Microbiol 2020; 10:2962. [PMID: 31969869 PMCID: PMC6960106 DOI: 10.3389/fmicb.2019.02962] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 12/09/2019] [Indexed: 12/16/2022] Open
Abstract
Viruses have evolved many mechanisms to escape host antiviral responses. Previously, we found that classical swine fever virus (CSFV) infection induces autophagy using the autophagosome as a self-replication site, thereby evading the host immune response and promoting long-term infection. However, the underlying mechanisms used by CSFV to enter autophagosomes and the mechanism by which autophagy promotes viral replication remain unclear. We found that CSFV infection inhibited autophagy receptor nuclear dot protein 52 kDa (NDP52) expression, ubiquitination, and SUMO2-4 modification. Further analyses revealed that CSFV mediated ubiquitination and SUMOylation of NDP52 via Pten-induced kinase 1 (PINK1)-Parkin. Moreover, NDP52 inhibition also inhibited CSFV replication and the induction of mitophagy marker proteins expression. Inhibition of NDP52 reduced CD63 expression and binding to CSFV E2 protein, which has an essential role in persistent CSFV infection. As NDP52 has a close relationship with the NF-κB innate immunity pathway and plays an important role in the antiviral response, we investigated whether NDP52 inhibited CSFV replication through the release of immune factors and antivirus signals. Our results showed that inhibiting NDP52 boosted interferon and TNF release and promoted NF-κB pathway activation. In summary, we found that NDP52 inhibition not only reduces CSFV binding and entry into autophagic vesicles, but also inhibits CSFV replication by active NF-κB antiviral immune pathways. Our data reveal a novel mechanism by which NDP52, an autophagy receptor, mediates CSFV infection, and provide new avenues for the development of antiviral strategies.
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Affiliation(s)
- Shuangqi Fan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Keke Wu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Chaowei Luo
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Xin Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Mengpo Zhao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Dan Song
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Shengming Ma
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Erpeng Zhu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Yuming Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Hongxing Ding
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Lin Yi
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Jun Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Mingqiu Zhao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Jinding Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
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45
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Mechanisms of Autophagy in Metabolic Stress Response. J Mol Biol 2020; 432:28-52. [DOI: 10.1016/j.jmb.2019.09.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/06/2019] [Accepted: 09/06/2019] [Indexed: 01/17/2023]
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46
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Valionyte E, Yang Y, Roberts SL, Kelly J, Lu B, Luo S. Lowering Mutant Huntingtin Levels and Toxicity: Autophagy-Endolysosome Pathways in Huntington's Disease. J Mol Biol 2019; 432:2673-2691. [PMID: 31786267 DOI: 10.1016/j.jmb.2019.11.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 11/04/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023]
Abstract
Huntington's disease (HD) is a monogenetic neurodegenerative disease, which serves as a model of neurodegeneration with protein aggregation. Autophagy has been suggested to possess a great value to tackle protein aggregation toxicity and neurodegenerative diseases. Current studies suggest that autophagy-endolysosomal pathways are critical for HD pathology. Here we review recent advancement in the studies of autophagy and selective autophagy relating HD. Restoration of autophagy flux and enhancement of selective removal of mutant huntingtin/disease-causing protein would be effective approaches towards tackling HD as well as other similar neurodegenerative disorders.
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Affiliation(s)
- Evelina Valionyte
- Peninsula Schools of Medicine and Dentistry, Institute of Translational and Stratified Medicine, University of Plymouth, Research Way, Plymouth PL6 8BU, UK
| | - Yi Yang
- Peninsula Schools of Medicine and Dentistry, Institute of Translational and Stratified Medicine, University of Plymouth, Research Way, Plymouth PL6 8BU, UK
| | - Sheridan L Roberts
- Peninsula Schools of Medicine and Dentistry, Institute of Translational and Stratified Medicine, University of Plymouth, Research Way, Plymouth PL6 8BU, UK
| | - Jack Kelly
- Peninsula Schools of Medicine and Dentistry, Institute of Translational and Stratified Medicine, University of Plymouth, Research Way, Plymouth PL6 8BU, UK
| | - Boxun Lu
- State Key Laboratory of Medical Neurobiology, Collaborative Innovation Center for Brain Science, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Shouqing Luo
- Peninsula Schools of Medicine and Dentistry, Institute of Translational and Stratified Medicine, University of Plymouth, Research Way, Plymouth PL6 8BU, UK.
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47
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Pohl C, Dikic I. Cellular quality control by the ubiquitin-proteasome system and autophagy. Science 2019; 366:818-822. [DOI: 10.1126/science.aax3769] [Citation(s) in RCA: 352] [Impact Index Per Article: 70.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
To achieve homeostasis, cells evolved dynamic and self-regulating quality control processes to adapt to new environmental conditions and to prevent prolonged damage. We discuss the importance of two major quality control systems responsible for degradation of proteins and organelles in eukaryotic cells: the ubiquitin-proteasome system (UPS) and autophagy. The UPS and autophagy form an interconnected quality control network where decision-making is self-organized on the basis of biophysical parameters (binding affinities, local concentrations, and avidity) and compartmentalization (through membranes, liquid-liquid phase separation, or the formation of aggregates). We highlight cellular quality control factors that delineate their differential deployment toward macromolecular complexes, liquid-liquid phase-separated subcellular structures, or membrane-bound organelles. Finally, we emphasize the need for continuous promotion of quantitative and mechanistic research into the roles of the UPS and autophagy in human pathophysiology.
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Affiliation(s)
- Christian Pohl
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, 60590 Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Ivan Dikic
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, 60590 Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe University, 60438 Frankfurt am Main, Germany
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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48
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Biological Functions of Autophagy Genes: A Disease Perspective. Cell 2019; 176:11-42. [PMID: 30633901 DOI: 10.1016/j.cell.2018.09.048] [Citation(s) in RCA: 1731] [Impact Index Per Article: 346.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 09/16/2018] [Accepted: 09/24/2018] [Indexed: 02/07/2023]
Abstract
The lysosomal degradation pathway of autophagy plays a fundamental role in cellular, tissue, and organismal homeostasis and is mediated by evolutionarily conserved autophagy-related (ATG) genes. Definitive etiological links exist between mutations in genes that control autophagy and human disease, especially neurodegenerative, inflammatory disorders and cancer. Autophagy selectively targets dysfunctional organelles, intracellular microbes, and pathogenic proteins, and deficiencies in these processes may lead to disease. Moreover, ATG genes have diverse physiologically important roles in other membrane-trafficking and signaling pathways. This Review discusses the biological functions of autophagy genes from the perspective of understanding-and potentially reversing-the pathophysiology of human disease and aging.
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49
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Lee S, Jeon YM, Cha SJ, Kim S, Kwon Y, Jo M, Jang YN, Lee S, Kim J, Kim SR, Lee KJ, Lee SB, Kim K, Kim HJ. PTK2/FAK regulates UPS impairment via SQSTM1/p62 phosphorylation in TARDBP/TDP-43 proteinopathies. Autophagy 2019; 16:1396-1412. [PMID: 31690171 DOI: 10.1080/15548627.2019.1686729] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
TARDBP/TDP-43 (TAR DNA binding protein) proteinopathies are a common feature in a variety of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and Alzheimer disease (AD). However, the molecular mechanisms underlying TARDBP-induced neurotoxicity are largely unknown. In this study, we demonstrated that TARDBP proteinopathies induce impairment in the ubiquitin proteasome system (UPS), as evidenced by an accumulation of ubiquitinated proteins and a reduction in proteasome activity in neuronal cells. Through kinase inhibitor screening, we identified PTK2/FAK (PTK2 protein tyrosine kinase 2) as a suppressor of neurotoxicity induced by UPS impairment. Importantly, PTK2 inhibition significantly reduced ubiquitin aggregates and attenuated TARDBP-induced cytotoxicity in a Drosophila model of TARDBP proteinopathies. We further identified that phosphorylation of SQSTM1/p62 (sequestosome 1) at S403 (p-SQSTM1 [S403]), a key component in the autophagic degradation of poly-ubiquitinated proteins, is increased upon TARDBP overexpression and is dependent on the activation of PTK2 in neuronal cells. Moreover, expressing a non-phosphorylated form of SQSTM1 (SQSTM1S403A) significantly repressed the accumulation of insoluble poly-ubiquitinated proteins and neurotoxicity induced by TARDBP overexpression in neuronal cells. In addition, TBK1 (TANK binding kinase 1), a kinase that phosphorylates S403 of SQSTM1, was found to be involved in the PTK2-mediated phosphorylation of SQSTM1. Taken together, our data suggest that the PTK2-TBK1-SQSTM1 axis plays a critical role in the pathogenesis of TARDBP by regulating neurotoxicity induced by UPS impairment. Therefore, targeting the PTK2-TBK1-SQSTM1 axis may represent a novel therapeutic intervention for neurodegenerative diseases with TARDBP proteinopathies.Abbreviations: ALP: macroautophagy/autophagy lysosomal pathway; ALS: amyotrophic lateral sclerosis; ATXN2: ataxin 2; BafA1: bafilomycin A1; cCASP3: cleaved caspase 3; CSNK2: casein kinase 2; FTLD: frontotemporal lobar degeneration; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; OPTN: optineurin; PTK2/FAK: PTK2 protein tyrosine kinase 2; SQSTM1/p62: sequestosome 1; TARDBP/TDP-43: TAR DNA binding protein; TBK1: TANK binding kinase 1; ULK1: unc-51 like autophagy activating kinase 1; UPS: ubiquitin-proteasome system.
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Affiliation(s)
- Shinrye Lee
- Dementia Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea
| | - Yu-Mi Jeon
- Dementia Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea
| | - Sun Joo Cha
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University , Cheonan, South Korea
| | - Seyeon Kim
- Dementia Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea.,Department of Brain & Cognitive Sciences, DGIST , Daegu, South Korea
| | - Younghwi Kwon
- Dementia Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea.,Department of Brain & Cognitive Sciences, DGIST , Daegu, South Korea
| | - Myungjin Jo
- Dementia Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea
| | - You-Na Jang
- Neural circuits Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea
| | - Seongsoo Lee
- Gwangju Center, Korea Basic Science Institute (KBSI) , Gwangju, South Korea
| | - Jaekwang Kim
- Dementia Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea
| | - Sang Ryong Kim
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Institute of Life Science & Biotechnology, Kyungpook National University , Daegu, South Korea.,Brain Science and Engineering Institute, Kyungpook National University , Daegu, South Korea
| | - Kea Joo Lee
- Neural circuits Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea
| | - Sung Bae Lee
- Department of Brain & Cognitive Sciences, DGIST , Daegu, South Korea
| | - Kiyoung Kim
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University , Cheonan, South Korea.,Department of Medical Biotechnology, Soonchunhyang University , Asan, South Korea
| | - Hyung-Jun Kim
- Dementia Research Group, Korea Brain Research Institute (KBRI) , Daegu, South Korea
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50
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Conway O, Akpinar HA, Rogov VV, Kirkin V. Selective Autophagy Receptors in Neuronal Health and Disease. J Mol Biol 2019; 432:2483-2509. [PMID: 31654670 DOI: 10.1016/j.jmb.2019.10.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/27/2019] [Accepted: 10/10/2019] [Indexed: 12/14/2022]
Abstract
Neurons are electrically excitable, postmitotic cells that perform sensory, relaying, and motor functions. Because of their unique morphological and functional specialization, cells of this type are sensitive to the stress caused by accumulation of misfolded proteins or damaged organelles. Autophagy is the fundamental mechanism that ensures sequestration of cytosolic material and its subsequent degradation in lysosomes of eukaryotic cells, thereby providing cell-autonomous nutrients and removing harmful cargos. Strikingly, mice and flies lacking functional autophagy develop early onset progressive neurodegeneration. Like in human neurodegenerative diseases (NDDs)-Alzheimer's disease, Parkinson's disease, frontotemporal dementia, Huntington's disease, and amyotrophic lateral sclerosis-characteristic protein aggregates observed in autophagy-deficient neurons in the animal models are indicators of the ongoing neuronal pathology. A number of selective autophagy receptors (SARs) have been characterized that interact both with the cargo and components of the autophagic machinery, thus providing the molecular basis for selective degradation of sizable cytosolic components. Interference with autophagy in experimental models, but also during the pathological vagaries in neurons, will thus have far-reaching consequences for a range of selective autophagy pathways critical for the normal functioning of the nervous system. Here, we review the key principles behind the selective autophagy and discuss how the SARs may be involved in the pathogenesis of NDDs. Using recently published examples, we also examine the emerging role of less well studied selective autophagy pathways in neuronal health and disease. We conclude by discussing targeting selective autophagy as an emerging therapeutic modality in NDDs.
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Affiliation(s)
- Owen Conway
- Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London SM2 5NG, UK
| | - Hafize Aysin Akpinar
- Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London SM2 5NG, UK
| | - Vladimir V Rogov
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt Am Main, Germany
| | - Vladimir Kirkin
- Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London SM2 5NG, UK.
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