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Hipp MS, Hartl FU. Interplay of Proteostasis Capacity and Protein Aggregation: Implications for Cellular Function and Disease. J Mol Biol 2024; 436:168615. [PMID: 38759929 DOI: 10.1016/j.jmb.2024.168615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/13/2024] [Accepted: 05/13/2024] [Indexed: 05/19/2024]
Abstract
Eukaryotic cells are equipped with an intricate proteostasis network (PN), comprising nearly 3,000 components dedicated to preserving proteome integrity and sustaining protein homeostasis. This protective system is particularly important under conditions of external and intrinsic cell stress, where inherently dynamic proteins may unfold and lose functionality. A decline in proteostasis capacity is associated with the aging process, resulting in a reduced folding efficiency of newly synthesized proteins and a deficit in the cellular capacity to degrade misfolded proteins. A critical consequence of PN insufficiency is the accumulation of cytotoxic protein aggregates that underlie various age-related neurodegenerative conditions and other pathologies. By interfering with specific proteostasis components, toxic aggregates place an excessive burden on the PN's ability to maintain proteome integrity. This initiates a feed-forward loop, wherein the generation of misfolded and aggregated proteins ultimately leads to proteostasis collapse and cellular demise.
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Affiliation(s)
- Mark S Hipp
- Department of Biomedical Sciences, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan, 1, 9713 AV Groningen, the Netherlands; Research School of Behavioural and Cognitive Neurosciences, University of Groningen, Groningen, the Netherlands; School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA.
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2
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Singh Gautam AK, Yu H, Yellman C, Elcock AH, Matouschek A. Design principles that protect the proteasome from self-destruction. Protein Sci 2022; 31:556-567. [PMID: 34878680 PMCID: PMC8862440 DOI: 10.1002/pro.4251] [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: 08/05/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 11/07/2022]
Abstract
The proteasome is a powerful intracellular protease that can degrade effectively any protein, self or foreign, for regulation, quality control, or immune response. Proteins are targeted for degradation by localizing them to the proteasome, typically by ubiquitin tags. At the same time, the proteasome is built from ~33 subunits, and their assembly into the complex and activity are tuned by post-translational modifications on long disordered regions on the subunits. Molecular modeling and biochemical experiments show that some of the disordered regions of proteasomal subunits can access the substrate recognition sites. All disordered regions tested, independent of location, are constructed from amino acid sequences that escape recognition. Replacing a disordered region with a sequence that is recognized by the proteasome leads to self-degradation and, in the case of an essential subunit, cell death.
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Affiliation(s)
| | - Houqing Yu
- Department of Molecular BiosciencesThe University of Texas at AustinAustinTexasUSA
| | - Christopher Yellman
- Department of Molecular BiosciencesThe University of Texas at AustinAustinTexasUSA
| | - Adrian H. Elcock
- Department of Biochemistry, Carver College of MedicineUniversity of IowaIowa CityIowaUSA
| | - Andreas Matouschek
- Department of Molecular BiosciencesThe University of Texas at AustinAustinTexasUSA
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Hommen F, Bilican S, Vilchez D. Protein clearance strategies for disease intervention. J Neural Transm (Vienna) 2021; 129:141-172. [PMID: 34689261 PMCID: PMC8541819 DOI: 10.1007/s00702-021-02431-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/10/2021] [Indexed: 02/06/2023]
Abstract
Protein homeostasis, or proteostasis, is essential for cell function and viability. Unwanted, damaged, misfolded and aggregated proteins are degraded by the ubiquitin–proteasome system (UPS) and the autophagy-lysosome pathway. Growing evidence indicates that alterations in these major proteolytic mechanisms lead to a demise in proteostasis, contributing to the onset and development of distinct diseases. Indeed, dysregulation of the UPS or autophagy is linked to several neurodegenerative, infectious and inflammatory disorders as well as cancer. Thus, modulation of protein clearance pathways is a promising approach for therapeutics. In this review, we discuss recent findings and open questions on how targeting proteolytic mechanisms could be applied for disease intervention.
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Affiliation(s)
- Franziska Hommen
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - Saygın Bilican
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany. .,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany. .,Faculty of Medicine, University Hospital Cologne, Cologne, Germany.
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Analysis of potential genetic biomarkers and molecular mechanism of smoking-related postmenopausal osteoporosis using weighted gene co-expression network analysis and machine learning. PLoS One 2021; 16:e0257343. [PMID: 34555052 PMCID: PMC8459994 DOI: 10.1371/journal.pone.0257343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 08/29/2021] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVES Smoking is a significant independent risk factor for postmenopausal osteoporosis, leading to genome variations in postmenopausal smokers. This study investigates potential biomarkers and molecular mechanisms of smoking-related postmenopausal osteoporosis (SRPO). MATERIALS AND METHODS The GSE13850 microarray dataset was downloaded from Gene Expression Omnibus (GEO). Gene modules associated with SRPO were identified using weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) analysis, and pathway and functional enrichment analyses. Feature genes were selected using two machine learning methods: support vector machine-recursive feature elimination (SVM-RFE) and random forest (RF). The diagnostic efficiency of the selected genes was assessed by gene expression analysis and receiver operating characteristic curve. RESULTS Eight highly conserved modules were detected in the WGCNA network, and the genes in the module that was strongly correlated with SRPO were used for constructing the PPI network. A total of 113 hub genes were identified in the core network using topological network analysis. Enrichment analysis results showed that hub genes were closely associated with the regulation of RNA transcription and translation, ATPase activity, and immune-related signaling. Six genes (HNRNPC, PFDN2, PSMC5, RPS16, TCEB2, and UBE2V2) were selected as genetic biomarkers for SRPO by integrating the feature selection of SVM-RFE and RF. CONCLUSION The present study identified potential genetic biomarkers and provided a novel insight into the underlying molecular mechanism of SRPO.
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Xiang C, Cong S, Liang B, Cong S. Bioinformatic gene analysis for potential therapeutic targets of Huntington's disease in pre-symptomatic and symptomatic stage. J Transl Med 2020; 18:388. [PMID: 33054835 PMCID: PMC7559361 DOI: 10.1186/s12967-020-02549-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 09/27/2020] [Indexed: 01/18/2023] Open
Abstract
Background Huntington’s disease (HD) is a neurodegenerative disorder characterized by psychiatric symptoms, serious motor and cognitive deficits. Certain pathological changes can already be observed in pre-symptomatic HD (pre-HD) patients; however, the underlying molecular pathogenesis is still uncertain and no effective treatments are available until now. Here, we reanalyzed HD-related differentially expressed genes from the GEO database between symptomatic HD patients, pre-HD individuals, and healthy controls using bioinformatics analysis, hoping to get more insight in the pathogenesis of both pre-HD and HD, and shed a light in the potential therapeutic targets of the disease. Methods Pre-HD and symptomatic HD differentially expressed genes (DEGs) were screened by bioinformatics analysis Gene Expression Omnibus (GEO) dataset GSE1751. A protein–protein interaction (PPI) network was used to select hub genes. Subsequently, Gene Ontology (GO) enrichment analysis of DEGs and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of hub genes were applied. Dataset GSE24250 was downloaded to verify our hub genes by the Kaplan–Meier method using Graphpad Prism 5.0. Finally, target miRNAs of intersected hub genes involved in pre-HD and symptomatic HD were predicted. Results A total of 37 and 985 DEGs were identified in pre-HD and symptomatic HD, respectively. The hub genes, SIRT1, SUZ12, and PSMC6, may be implicated in pre-HD, and the hub genes, FIS1, SIRT1, CCNH, SUZ12, and 10 others, may be implicated in symptomatic HD. The intersected hub genes, SIRT1 and SUZ12, and their predicted target miRNAs, in particular miR-22-3p and miR-19b, may be significantly associated with pre-HD. Conclusion The PSMC6, SIRT1, and SUZ12 genes and their related ubiquitin-mediated proteolysis, transcriptional dysregulation, and histone metabolism are significantly associated with pre-HD. FIS1, CCNH, and their related mitochondrial disruption and transcriptional dysregulation processes are related to symptomatic HD, which might shed a light on the elucidation of potential therapeutic targets in HD.
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Affiliation(s)
- Chunchen Xiang
- Department of Neurology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Heping District, Shenyang, 110004, Liaoning, People's Republic of China
| | - Shengri Cong
- Department of Neurology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Heping District, Shenyang, 110004, Liaoning, People's Republic of China
| | - Bin Liang
- Bioinformatics of Department, School of Life Sciences, China Medical University, Shenyang, China
| | - Shuyan Cong
- Department of Neurology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Heping District, Shenyang, 110004, Liaoning, People's Republic of China.
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Proteasome Subunits Involved in Neurodegenerative Diseases. Arch Med Res 2020; 52:1-14. [PMID: 32962866 DOI: 10.1016/j.arcmed.2020.09.007] [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: 01/29/2020] [Revised: 07/25/2020] [Accepted: 09/04/2020] [Indexed: 12/29/2022]
Abstract
The ubiquitin-proteasome system is the major pathway for the maintenance of protein homeostasis. Its inhibition causes accumulation of ubiquitinated proteins; this accumulation has been associated with several of the most common neurodegenerative diseases. Several genetic factors have been identified for most neurodegenerative diseases, however, most cases are considered idiopathic, thus making the study of the mechanisms of protein accumulation a relevant field of research. It is often mentioned that the biggest risk factor for neurodegenerative diseases is aging, and several groups have reported an age-related alteration of the expression of some of the 26S proteasome subunits and a reduction of its activity. Proteasome subunits interact with proteins that are known to accumulate in neurodegenerative diseases such as α-synuclein in Parkinson's, tau in Alzheimer's, and huntingtin in Huntington's diseases. These interactions have been explored for several years, but only until recently, we are beginning to understand them. In this review, we discuss the known interactions, the underlying patterns, and the phenotypes associated with the 26S proteasome subunits in the etiology and progression of neurodegenerative diseases where there is evidence of proteasome involvement. Special emphasis is made in reviewing proteasome subunits that interact with proteins known to have an age-related altered expression or to be involved in neurodegenerative diseases to explore key effectors that may trigger or augment their progression. Interestingly, while the causes of age-related reduction of some of the proteasome subunits are not known, there are specific relationships between the observed neurodegenerative disease and the affected proteasome subunits.
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Tomita T, Matouschek A. Substrate selection by the proteasome through initiation regions. Protein Sci 2019; 28:1222-1232. [PMID: 31074920 DOI: 10.1002/pro.3642] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 01/04/2023]
Abstract
Proteins in the cell have to be eliminated once their function is no longer desired or they become damaged. Most regulated protein degradation is achieved by a large enzymatic complex called the proteasome. Many proteasome substrates are targeted for degradation by the covalent attachment of ubiquitin molecules. Ubiquitinated proteins can be bound by the proteasome, but for proteolysis to occur the proteasome needs to find a disordered tail somewhere in the target at which it initiates degradation. The initiation step contributes to the specificity of proteasomal degradation. Here, we review how the proteasome selects initiation sites within its substrates and discuss how the initiation step affects physiological processes.
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Affiliation(s)
- Takuya Tomita
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, 78712
| | - Andreas Matouschek
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, 78712
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Abstract
The ubiquitin proteasome system controls the concentrations of regulatory proteins and removes damaged and misfolded proteins from cells. Proteins are targeted to the protease at the center of this system, the proteasome, by ubiquitin tags, but ubiquitin is also used as a signal in other cellular processes. Specificity is conferred by the size and structure of the ubiquitin tags, which are recognized by receptors associated with the different cellular processes. However, the ubiquitin code remains ambiguous, and the same ubiquitin tag can target different proteins to different fates. After binding substrate protein at the ubiquitin tag, the proteasome initiates degradation at a disordered region in the substrate. The proteasome has pronounced preferences for the initiation site, and its recognition represents a second component of the degradation signal.
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Affiliation(s)
- Houqing Yu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712;
| | - Andreas Matouschek
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712;
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Kim YE, Hosp F, Frottin F, Ge H, Mann M, Hayer-Hartl M, Hartl FU. Soluble Oligomers of PolyQ-Expanded Huntingtin Target a Multiplicity of Key Cellular Factors. Mol Cell 2016; 63:951-64. [PMID: 27570076 DOI: 10.1016/j.molcel.2016.07.022] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 06/17/2016] [Accepted: 07/21/2016] [Indexed: 11/17/2022]
Abstract
Huntington's disease is one of several neurodegenerative disorders characterized by the aggregation of polyglutamine (polyQ)-expanded mutant protein. How polyQ aggregation leads to cellular dysfunction is not well understood. Here, we analyzed aberrant protein interactions of soluble oligomers and insoluble inclusions of mutant huntingtin using in-cell single molecule fluorescence spectroscopy and quantitative proteomics. We find that the interactome of soluble oligomers is highly complex, with an enrichment of RNA-binding proteins as well as proteins functioning in ribosome biogenesis, translation, transcription, and vesicle transport. The oligomers frequently target proteins containing extended low-complexity sequences, potentially interfering with key cellular pathways. In contrast, the insoluble inclusions are less interactive and associate strongly with protein quality control components, such as Hsp40 chaperones and factors of the ubiquitin-proteasome system. Our results suggest a "multiple hit" model for the pathogenic effects of mutant huntingtin, with soluble forms engaging more extensively in detrimental interactions than insoluble aggregates.
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Affiliation(s)
- Yujin E Kim
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82159 Martinsried, Germany
| | - Fabian Hosp
- Department of Proteomics & Signal Transduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82159 Martinsried, Germany
| | - Frédéric Frottin
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82159 Martinsried, Germany
| | - Hui Ge
- Novartis Institutes for Biomedical Research, No. 2 BoYun Road, Pudong, Shanghai 201203, China
| | - Matthias Mann
- Department of Proteomics & Signal Transduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82159 Martinsried, Germany
| | - Manajit Hayer-Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82159 Martinsried, Germany.
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82159 Martinsried, Germany; Munich Cluster for Systems Neurology, Adolf-Butenandt-Institut, Ludwig-Maximilians-Universität München, Schillerstrasse 44, 80336 München, Germany.
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The life cycle of the 26S proteasome: from birth, through regulation and function, and onto its death. Cell Res 2016; 26:869-85. [PMID: 27444871 PMCID: PMC4973335 DOI: 10.1038/cr.2016.86] [Citation(s) in RCA: 213] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The 26S proteasome is a large, ∼2.5 MDa, multi-catalytic ATP-dependent protease complex that serves as the degrading arm of the ubiquitin system, which is the major pathway for regulated degradation of cytosolic, nuclear and membrane proteins in all eukaryotic organisms.
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Lenzi P, Lazzeri G, Biagioni F, Busceti CL, Gambardella S, Salvetti A, Fornai F. The Autophagoproteasome a Novel Cell Clearing Organelle in Baseline and Stimulated Conditions. Front Neuroanat 2016; 10:78. [PMID: 27493626 PMCID: PMC4955296 DOI: 10.3389/fnana.2016.00078] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 07/05/2016] [Indexed: 12/24/2022] Open
Abstract
Protein clearing pathways named autophagy (ATG) and ubiquitin proteasome (UP) control homeostasis within eukaryotic cells, while their dysfunction produces neurodegeneration. These pathways are viewed as distinct biochemical cascades occurring within specific cytosolic compartments owing pathway-specific enzymatic activity. Recent data strongly challenged the concept of two morphologically distinct and functionally segregated compartments. In fact, preliminary evidence suggests the convergence of these pathways to form a novel organelle named autophagoproteasome. This is characterized in the present study by using a cell line where, mTOR activity is upregulated and autophagy is suppressed. This was reversed dose-dependently by administering the mTOR inhibitor rapamycin. Thus, we could study autophagoproteasomes when autophagy was either suppressed or stimulated. The occurrence of autophagoproteasome was shown also in non-human cell lines. Ultrastructural morphometry, based on the stochiometric binding of immunogold particles allowed the quantitative evaluation of ATG and UP component within autophagoproteasomes. The number of autophagoproteasomes increases following mTOR inhibition. Similarly, mTOR inhibition produces overexpression of both LC3 and P20S particles. This is confirmed by the fact that the ratio of free vs. autophagosome-bound LC3 is similar to that measured for P20S, both in baseline conditions and following mTOR inhibition. Remarkably, within autophagoproteasomes there is a slight prevalence of ATG compared with UP components for low rapamycin doses, whereas for higher rapamycin doses UP increases more than ATG. While LC3 is widely present within cytosol, UP is strongly polarized within autophagoproteasomes. These fine details were evident at electron microscopy but could not be deciphered by using confocal microscopy. Despite its morphological novelty autophagoproteasomes appear in the natural site where clearing pathways (once believed to be anatomically segregated) co-exist and they are likely to interact at molecular level. In fact, LC3 and P20S co-immunoprecipitate, suggesting a specific binding and functional interplay, which may be altered by inhibiting mTOR. In summary, ATG and UP often represent two facets of a single organelle, in which unexpected amount of enzymatic activity should be available. Thus, autophagoproteasome may represent a sophisticated ultimate clearing apparatus.
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Affiliation(s)
- Paola Lenzi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy
| | - Gloria Lazzeri
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy
| | - Francesca Biagioni
- Istituti di Ricovero e Cura a Carattere Scientifico (I.R.C.C.S.), Neuromed Pozzilli, Italy
| | - Carla L Busceti
- Istituti di Ricovero e Cura a Carattere Scientifico (I.R.C.C.S.), Neuromed Pozzilli, Italy
| | - Stefano Gambardella
- Istituti di Ricovero e Cura a Carattere Scientifico (I.R.C.C.S.), Neuromed Pozzilli, Italy
| | - Alessandra Salvetti
- Department of Clinical and Experimental Medicine, University of Pisa Pisa, Italy
| | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of PisaPisa, Italy; Istituti di Ricovero e Cura a Carattere Scientifico (I.R.C.C.S.), NeuromedPozzilli, Italy
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12
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Dasgupta S, Fishman MA, Mahallati H, Castro LM, Tashima AK, Ferro ES, Fricker LD. Reduced Levels of Proteasome Products in a Mouse Striatal Cell Model of Huntington's Disease. PLoS One 2015; 10:e0145333. [PMID: 26691307 PMCID: PMC4686214 DOI: 10.1371/journal.pone.0145333] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 12/02/2015] [Indexed: 12/25/2022] Open
Abstract
Huntington's disease is the result of a long polyglutamine tract in the gene encoding huntingtin protein, which in turn causes a large number of cellular changes and ultimately results in neurodegeneration of striatal neurons. Although many theories have been proposed, the precise mechanism by which the polyglutamine expansion causes cellular changes is not certain. Some evidence supports the hypothesis that the long polyglutamine tract inhibits the proteasome, a multiprotein complex involved in protein degradation. However, other studies report normal proteasome function in cells expressing long polyglutamine tracts. The controversy may be due to the methods used to examine proteasome activity in each of the previous studies. In the present study, we measured proteasome function by examining levels of endogenous peptides that are products of proteasome cleavage. Peptide levels were compared among mouse striatal cell lines expressing either 7 glutamines (STHdhQ7/Q7) or 111 glutamines in the huntingtin protein, either heterozygous (STHdhQ7/Q111) or homozygous (STHdhQ111/Q111). Both of the cell lines expressing huntingtin with 111 glutamines showed a large reduction in nearly all of the peptides detected in the cells, relative to levels of these peptides in cells homozygous for 7 glutamines. Treatment of STHdhQ7/Q7 cells with proteasome inhibitors epoxomicin or bortezomib also caused a large reduction in most of these peptides, suggesting that they are products of proteasome-mediated cleavage of cellular proteins. Taken together, these results support the hypothesis that proteasome function is impaired by the expression of huntingtin protein containing long polyglutamine tracts.
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Affiliation(s)
- Sayani Dasgupta
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, New York, 10461, United States of America
| | - Michael A. Fishman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, New York, 10461, United States of America
| | - Hana Mahallati
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, New York, 10461, United States of America
| | - Leandro M. Castro
- São Paulo State University (UNESP), Experimental Campus on the São Paulo Coast, São Vicente, 11330–900, SP, Brazil
| | - Alexandre K. Tashima
- Department of Biochemistry, Escola Paulista de Medicina, Federal University of Sao Paulo, Sao Paulo, SP, 04023–901, SP, Brazil
| | - Emer S. Ferro
- Department of Pharmacology, Biomedical Science Institute, University of São Paulo, São Paulo, 05508–000, SP, Brazil
| | - Lloyd D. Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, New York, 10461, United States of America
- Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, New York, 10461, United States of America
- * E-mail:
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Jang ER, Jang H, Shi P, Popa G, Jeoung M, Galperin E. Spatial control of Shoc2-scaffold-mediated ERK1/2 signaling requires remodeling activity of the ATPase PSMC5. J Cell Sci 2015; 128:4428-41. [PMID: 26519477 DOI: 10.1242/jcs.177543] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 10/21/2015] [Indexed: 12/13/2022] Open
Abstract
The scaffold protein Shoc2 accelerates activity of the ERK1 and ERK2 (ERK1/2, also known as MAPK3 and MAPK1) pathway. Mutations in Shoc2 result in Noonan-like RASopathy, a developmental disorder with a wide spectrum of symptoms. The amplitude of the ERK1/2 signals transduced through the complex is fine-tuned by the HUWE1-mediated ubiquitylation of Shoc2 and its signaling partner RAF-1. Here, we provide a mechanistic basis of how ubiquitylation of Shoc2 and RAF-1 is controlled. We demonstrate that the newly identified binding partner of Shoc2, the (AAA+) ATPase PSMC5, triggers translocation of Shoc2 to endosomes. At the endosomes, PSMC5 displaces the E3 ligase HUWE1 from the scaffolding complex to attenuate ubiquitylation of Shoc2 and RAF-1. We show that a RASopathy mutation that changes the subcellular distribution of Shoc2 leads to alterations in Shoc2 ubiquitylation due to the loss of accessibility to PSMC5. In summary, our results demonstrate that PSMC5 is a new and important player involved in regulating ERK1/2 signal transmission through the remodeling of Shoc2 scaffold complex in a spatially-defined manner.
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Affiliation(s)
- Eun Ryoung Jang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - HyeIn Jang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Ping Shi
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Gabriel Popa
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Myoungkun Jeoung
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Emilia Galperin
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
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Acosta-Alvear D, Cho MY, Wild T, Buchholz TJ, Lerner AG, Simakova O, Hahn J, Korde N, Landgren O, Maric I, Choudhary C, Walter P, Weissman JS, Kampmann M. Paradoxical resistance of multiple myeloma to proteasome inhibitors by decreased levels of 19S proteasomal subunits. eLife 2015; 4:e08153. [PMID: 26327694 PMCID: PMC4602331 DOI: 10.7554/elife.08153] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 08/31/2015] [Indexed: 01/06/2023] Open
Abstract
Hallmarks of cancer, including rapid growth and aneuploidy, can result in non-oncogene addiction to the proteostasis network that can be exploited clinically. The defining example is the exquisite sensitivity of multiple myeloma (MM) to 20S proteasome inhibitors, such as carfilzomib. However, MM patients invariably acquire resistance to these drugs. Using a next-generation shRNA platform, we found that proteostasis factors, including chaperones and stress-response regulators, controlled the response to carfilzomib. Paradoxically, 19S proteasome regulator knockdown induced resistance to carfilzomib in MM and non-MM cells. 19S subunit knockdown did not affect the activity of the 20S subunits targeted by carfilzomib nor their inhibition by the drug, suggesting an alternative mechanism, such as the selective accumulation of protective factors. In MM patients, lower 19S levels predicted a diminished response to carfilzomib-based therapies. Together, our findings suggest that an understanding of network rewiring can inform development of new combination therapies to overcome drug resistance. DOI:http://dx.doi.org/10.7554/eLife.08153.001 Cells have several mechanisms for removing proteins that have been damaged or are no longer needed. One of these mechanisms is carried out by a large protein complex called the proteasome. Drugs that block the proteasome are toxic to all cells, and a type of blood cancer called multiple myeloma is particularly sensitive to these ‘proteasome inhibitors’. However, tumors in patients with multiple myeloma can also become resistant to these drugs. Using a genetic approach, Acosta-Alvear et al. identified the factors that control the sensitivity of cells to proteasome inhibitors. In particular, reducing the levels of other factors that contribute to protein balance made the cells more sensitive. Using a combination of proteasome inhibitors and drugs that target these other factors could prove to be useful in the fight against multiple myeloma. The proteasome complex contains two types of subunits: regulatory subunits that recognize the proteins that need to be degraded, and catalytic subunits that degrade the proteins. The results of Acosta-Alvear et al. revealed how varying the levels of these two subunits influenced the sensitivity of cells to inhibitors. While decreasing the levels of catalytic subunits made the cells more sensitive, as expected, decreasing the level of regulatory subunits surprisingly made the cells resistant to the inhibitors. A possible explanation for this paradoxical result is that certain proteins are less effectively degraded by the proteasome in these cells, and that the buildup of these proteins protects the cells against the drugs. Acosta-Alvear et al. also found that lower levels of regulatory subunits desensitized multiple myeloma patients to therapy based on proteasome inhibition, suggesting that results from the genetic screen carried out in cells can predict clinical resistance mechanisms and guide the development of future therapies to increase patient survival. DOI:http://dx.doi.org/10.7554/eLife.08153.002
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Affiliation(s)
- Diego Acosta-Alvear
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, San Francisco, United States
| | - Min Y Cho
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Thomas Wild
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Tonia J Buchholz
- Onyx Pharmaceuticals, Inc. an Amgen subsidiary, South San Francisco, United States
| | - Alana G Lerner
- Onyx Pharmaceuticals, Inc. an Amgen subsidiary, South San Francisco, United States
| | - Olga Simakova
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, United States
| | - Jamie Hahn
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, United States
| | - Neha Korde
- Multiple Myeloma Section, Lymphoid Malignancies Branch, National Cancer Institute, Bethesda, United States.,Myeloma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, United States
| | - Ola Landgren
- Multiple Myeloma Section, Lymphoid Malignancies Branch, National Cancer Institute, Bethesda, United States.,Myeloma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, United States
| | - Irina Maric
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, United States
| | - Chunaram Choudhary
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, San Francisco, United States
| | - Jonathan S Weissman
- Howard Hughes Medical Institute, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Martin Kampmann
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, San Francisco, United States
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15
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Walther DM, Kasturi P, Zheng M, Pinkert S, Vecchi G, Ciryam P, Morimoto RI, Dobson CM, Vendruscolo M, Mann M, Hartl FU. Widespread Proteome Remodeling and Aggregation in Aging C. elegans. Cell 2015; 161:919-32. [PMID: 25957690 PMCID: PMC4643853 DOI: 10.1016/j.cell.2015.03.032] [Citation(s) in RCA: 393] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/12/2015] [Accepted: 02/24/2015] [Indexed: 12/12/2022]
Abstract
Aging has been associated with a progressive decline of proteostasis, but how this process affects proteome composition remains largely unexplored. Here, we profiled more than 5,000 proteins along the lifespan of the nematode C. elegans. We find that one-third of proteins change in abundance at least 2-fold during aging, resulting in a severe proteome imbalance. These changes are reduced in the long-lived daf-2 mutant but are enhanced in the short-lived daf-16 mutant. While ribosomal proteins decline and lose normal stoichiometry, proteasome complexes increase. Proteome imbalance is accompanied by widespread protein aggregation, with abundant proteins that exceed solubility contributing most to aggregate load. Notably, the properties by which proteins are selected for aggregation differ in the daf-2 mutant, and an increased formation of aggregates associated with small heat-shock proteins is observed. We suggest that sequestering proteins into chaperone-enriched aggregates is a protective strategy to slow proteostasis decline during nematode aging.
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Affiliation(s)
- Dirk M Walther
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Prasad Kasturi
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Min Zheng
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Stefan Pinkert
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Giulia Vecchi
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
| | - Prajwal Ciryam
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK; Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL 60208, USA
| | - Richard I Morimoto
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL 60208, USA
| | | | | | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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16
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Zheng C, Geetha T, Babu JR. Failure of ubiquitin proteasome system: risk for neurodegenerative diseases. NEURODEGENER DIS 2014; 14:161-75. [PMID: 25413678 DOI: 10.1159/000367694] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/19/2014] [Indexed: 11/19/2022] Open
Abstract
The ubiquitin proteasome system (UPS) is the primary proteolytic quality control system in cells and has an essential function in the nervous system. UPS dysfunction has been linked to neurodegenerative conditions, including Alzheimer's, Parkinson's and Huntington's diseases. The pathology of neurodegenerative diseases is characterized by the abnormal accumulation of insoluble protein aggregates or inclusion bodies within neurons. The failure or dysregulation of the UPS prevents the degradation of misfolded/aberrant proteins, leading to deficient synaptic function that eventually affects the nervous system. In this review, we discuss the UPS and its physiological roles in the nervous system, its influence on neuronal function, and how UPS dysfunction contributes to the development of neurodegenerative diseases.
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Affiliation(s)
- Chen Zheng
- Department of Nutrition, Dietetics, and Hospitality Management, Auburn University, Auburn, Ala., USA
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17
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Hipp MS, Park SH, Hartl FU. Proteostasis impairment in protein-misfolding and -aggregation diseases. Trends Cell Biol 2014; 24:506-14. [DOI: 10.1016/j.tcb.2014.05.003] [Citation(s) in RCA: 449] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 12/27/2022]
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18
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Kabani M, Redeker V, Melki R. A role for the proteasome in the turnover of Sup35p and in [PSI(+) ] prion propagation. Mol Microbiol 2014; 92:507-28. [PMID: 24589377 DOI: 10.1111/mmi.12572] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2014] [Indexed: 01/21/2023]
Abstract
Yeast prions are superb models for understanding the mechanisms of self-perpetuating protein aggregates formation. [PSI(+) ] stands among the most documented yeast prions and results from self-assembly of the translation termination factor Sup35p into protein fibrils. A plethora of cellular factors were shown to affect [PSI(+) ] formation and propagation. Clearance of Sup35p prion particles is however poorly understood and documented. Here, we investigated the role of the proteasome in the degradation of Sup35p and in [PSI(+) ] prion propagation. We found that cells lacking the RPN4 gene, which have reduced intracellular proteasome pools, accumulated Sup35p and have defects in [PSI(+) ] formation and propagation. Sup35p is degraded in vitro by the 26S and 20S proteasomes in a ubiquitin-independent manner, generating an array of amyloidogenic peptides derived from its prion-domain. We also demonstrate the formation of a proteasome-resistant fragment spanning residues 83-685 which is devoid of the prion-domain that is essential for [PSI(+) ] propagation. Most important was the finding that the 26S and 20S proteasomes degrade Sup35p fibrils in vitro and abolish their infectivity. Our results point to an overlooked role of the proteasome in clearing toxic protein aggregates, and have important implications for a better understanding of the life cycle of infectious protein assemblies.
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Affiliation(s)
- Mehdi Kabani
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Bât. 34, Avenue de la Terrasse, F-91190, Gif-sur-Yvette, France
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19
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Schipper-Krom S, Juenemann K, Jansen AH, Wiemhoefer A, van den Nieuwendijk R, Smith DL, Hink MA, Bates GP, Overkleeft H, Ovaa H, Reits E. Dynamic recruitment of active proteasomes into polyglutamine initiated inclusion bodies. FEBS Lett 2013; 588:151-9. [PMID: 24291262 DOI: 10.1016/j.febslet.2013.11.023] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 11/20/2022]
Abstract
Neurodegenerative disorders such as Huntington's disease are hallmarked by neuronal intracellular inclusion body formation. Whether proteasomes are irreversibly recruited into inclusion bodies in these protein misfolding disorders is a controversial subject. In addition, it has been proposed that the proteasomes may become clogged by the aggregated protein fragments, leading to impairment of the ubiquitin-proteasome system. Here, we show by fluorescence pulse-chase experiments in living cells that proteasomes are dynamically and reversibly recruited into inclusion bodies. As these recruited proteasomes remain catalytically active and accessible to substrates, our results challenge the concept of proteasome sequestration and impairment in Huntington's disease, and support the reported absence of proteasome impairment in mouse models of Huntington's disease.
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Affiliation(s)
- Sabine Schipper-Krom
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, The Netherlands
| | - Katrin Juenemann
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, The Netherlands
| | - Anne H Jansen
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, The Netherlands
| | - Anne Wiemhoefer
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, The Netherlands
| | - Rianne van den Nieuwendijk
- Department of Bio-Organic Synthesis, Institute of Chemistry, University of Leiden, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Donna L Smith
- Department of Medical and Molecular Genetics, King's College London, Guy's Hospital, Great Maze Pond, SE1 9RT London, United Kingdom
| | - Mark A Hink
- Section Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands
| | - Gillian P Bates
- Department of Medical and Molecular Genetics, King's College London, Guy's Hospital, Great Maze Pond, SE1 9RT London, United Kingdom
| | - Hermen Overkleeft
- Department of Bio-Organic Synthesis, Institute of Chemistry, University of Leiden, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Huib Ovaa
- Department of Cell Biology II, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Eric Reits
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, The Netherlands.
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20
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Juenemann K, Schipper-Krom S, Wiemhoefer A, Kloss A, Sanz Sanz A, Reits EAJ. Expanded polyglutamine-containing N-terminal huntingtin fragments are entirely degraded by mammalian proteasomes. J Biol Chem 2013; 288:27068-27084. [PMID: 23908352 DOI: 10.1074/jbc.m113.486076] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Huntington disease is a neurodegenerative disorder caused by an expanded polyglutamine (polyQ) repeat within the protein huntingtin (Htt). N-terminal fragments of the mutant Htt (mHtt) proteins containing the polyQ repeat are aggregation-prone and form intracellular inclusion bodies. Improving the clearance of mHtt fragments by intracellular degradation pathways is relevant to obviate toxic mHtt species and subsequent neurodegeneration. Because the proteasomal degradation pathway has been the subject of controversy regarding the processing of expanded polyQ repeats, we examined whether the proteasome can efficiently degrade Htt-exon1 with an expanded polyQ stretch both in neuronal cells and in vitro. Upon targeting mHtt-exon1 to the proteasome, rapid and complete clearance of mHtt-exon1 was observed. Proteasomal degradation of mHtt-exon1 was devoid of polyQ peptides as partial cleavage products by incomplete proteolysis, indicating that mammalian proteasomes are capable of efficiently degrading expanded polyQ sequences without an inhibitory effect on the proteasomal activity.
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Affiliation(s)
- Katrin Juenemann
- Department of Cellbiology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
| | - Sabine Schipper-Krom
- Department of Cellbiology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Anne Wiemhoefer
- Department of Cellbiology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Alexander Kloss
- Institut für Biochemie/CCM, Charité-Universitätsmedizin Berlin, Monbijoustrasse 2, Berlin 10117, Germany
| | - Alicia Sanz Sanz
- Department of Cellbiology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Eric A J Reits
- Department of Cellbiology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
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21
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Park SH, Kukushkin Y, Gupta R, Chen T, Konagai A, Hipp M, Hayer-Hartl M, Hartl F. PolyQ Proteins Interfere with Nuclear Degradation of Cytosolic Proteins by Sequestering the Sis1p Chaperone. Cell 2013; 154:134-45. [DOI: 10.1016/j.cell.2013.06.003] [Citation(s) in RCA: 233] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 05/07/2013] [Accepted: 05/30/2013] [Indexed: 01/25/2023]
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22
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Gillis J, Schipper-Krom S, Juenemann K, Gruber A, Coolen S, van den Nieuwendijk R, van Veen H, Overkleeft H, Goedhart J, Kampinga HH, Reits EA. The DNAJB6 and DNAJB8 protein chaperones prevent intracellular aggregation of polyglutamine peptides. J Biol Chem 2013; 288:17225-37. [PMID: 23612975 DOI: 10.1074/jbc.m112.421685] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Fragments of proteins containing an expanded polyglutamine (polyQ) tract are thought to initiate aggregation and toxicity in at least nine neurodegenerative diseases, including Huntington's disease. Because proteasomes appear unable to digest the polyQ tract, which can initiate intracellular protein aggregation, preventing polyQ peptide aggregation by chaperones should greatly improve polyQ clearance and prevent aggregate formation. Here we expressed polyQ peptides in cells and show that their intracellular aggregation is prevented by DNAJB6 and DNAJB8, members of the DNAJ (Hsp40) chaperone family. In contrast, HSPA/Hsp70 and DNAJB1, also members of the DNAJ chaperone family, did not prevent peptide-initiated aggregation. Intriguingly, DNAJB6 and DNAJB8 also affected the soluble levels of polyQ peptides, indicating that DNAJB6 and DNAJB8 inhibit polyQ peptide aggregation directly. Together with recent data showing that purified DNAJB6 can suppress fibrillation of polyQ peptides far more efficiently than polyQ expanded protein fragments in vitro, we conclude that the mechanism of DNAJB6 and DNAJB8 is suppression of polyQ protein aggregation by directly binding the polyQ tract.
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Affiliation(s)
- Judith Gillis
- Department of Cell Biology and Histology, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
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23
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Abstract
Protein aggregation is being found to be associated with an increasing number of human diseases. Aggregation can lead to a loss of function (lack of active protein) or to a toxic gain of function (cytotoxicity associated with protein aggregates). Although potentially harmful, protein sequences predisposed to aggregation seem to be ubiquitous in all kingdoms of life, which suggests an evolutionary advantage to having such segments in polypeptide sequences. In fact, aggregation-prone segments are essential for protein folding and for mediating certain protein-protein interactions. Moreover, cells use protein aggregates for a wide range of functions. Against this background, life has adapted to tolerate the presence of potentially dangerous aggregation-prone sequences by constraining and counteracting the aggregation process. In the present review, we summarize the current knowledge of the advantages associated with aggregation-prone stretches in proteomes and the strategies that cellular systems have developed to control the aggregation process.
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24
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Chondrogianni N, Petropoulos I, Grimm S, Georgila K, Catalgol B, Friguet B, Grune T, Gonos ES. Protein damage, repair and proteolysis. Mol Aspects Med 2012; 35:1-71. [PMID: 23107776 DOI: 10.1016/j.mam.2012.09.001] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 09/26/2012] [Indexed: 01/10/2023]
Abstract
Proteins are continuously affected by various intrinsic and extrinsic factors. Damaged proteins influence several intracellular pathways and result in different disorders and diseases. Aggregation of damaged proteins depends on the balance between their generation and their reversal or elimination by protein repair systems and degradation, respectively. With regard to protein repair, only few repair mechanisms have been evidenced including the reduction of methionine sulfoxide residues by the methionine sulfoxide reductases, the conversion of isoaspartyl residues to L-aspartate by L-isoaspartate methyl transferase and deglycation by phosphorylation of protein-bound fructosamine by fructosamine-3-kinase. Protein degradation is orchestrated by two major proteolytic systems, namely the lysosome and the proteasome. Alteration of the function for both systems has been involved in all aspects of cellular metabolic networks linked to either normal or pathological processes. Given the importance of protein repair and degradation, great effort has recently been made regarding the modulation of these systems in various physiological conditions such as aging, as well as in diseases. Genetic modulation has produced promising results in the area of protein repair enzymes but there are not yet any identified potent inhibitors, and, to our knowledge, only one activating compound has been reported so far. In contrast, different drugs as well as natural compounds that interfere with proteolysis have been identified and/or developed resulting in homeostatic maintenance and/or the delay of disease progression.
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Affiliation(s)
- Niki Chondrogianni
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Helenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece.
| | - Isabelle Petropoulos
- Laboratoire de Biologie Cellulaire du Vieillissement, UR4-UPMC, IFR 83, Université Pierre et Marie Curie-Paris 6, 4 Place Jussieu, 75005 Paris, France
| | - Stefanie Grimm
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller University, Dornburger Straße 24, 07743 Jena, Germany
| | - Konstantina Georgila
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Helenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece
| | - Betul Catalgol
- Department of Biochemistry, Faculty of Medicine, Genetic and Metabolic Diseases Research Center (GEMHAM), Marmara University, Haydarpasa, Istanbul, Turkey
| | - Bertrand Friguet
- Laboratoire de Biologie Cellulaire du Vieillissement, UR4-UPMC, IFR 83, Université Pierre et Marie Curie-Paris 6, 4 Place Jussieu, 75005 Paris, France
| | - Tilman Grune
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller University, Dornburger Straße 24, 07743 Jena, Germany
| | - Efstathios S Gonos
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Helenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece.
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25
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The Ubiquitin-Proteasome System in Huntington's Disease: Are Proteasomes Impaired, Initiators of Disease, or Coming to the Rescue? Biochem Res Int 2012; 2012:837015. [PMID: 23050151 PMCID: PMC3462393 DOI: 10.1155/2012/837015] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 08/14/2012] [Accepted: 08/19/2012] [Indexed: 12/11/2022] Open
Abstract
Huntington's disease is a progressive neurodegenerative disease, caused by a polyglutamine expansion in the huntingtin protein. A prominent hallmark of the disease is the presence of intracellular aggregates initiated by N-terminal huntingtin fragments containing the polyglutamine repeat, which recruit components of the ubiquitin-proteasome system. While it is commonly thought that proteasomes are irreversibly sequestered into these aggregates leading to impairment of the ubiquitin-proteasome system, the data on proteasomal impairment in Huntington's disease is contradictory. In addition, it has been suggested that proteasomes are unable to actually cleave polyglutamine sequences in vitro, thereby releasing aggregation-prone polyglutamine peptides in cells. Here, we discuss how the proteasome is involved in the various stages of polyglutamine aggregation in Huntington's disease, and how alterations in activity may improve clearance of mutant huntingtin fragments.
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26
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The Aggregation of Huntingtin and α-Synuclein. JOURNAL OF BIOPHYSICS 2012; 2012:606172. [PMID: 22899913 PMCID: PMC3412099 DOI: 10.1155/2012/606172] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 05/15/2012] [Accepted: 05/17/2012] [Indexed: 12/23/2022]
Abstract
Huntington's and Parkinson's diseases are neurodegenerative disorders associated with unusual protein interactions. Although the origin and evolution of these diseases are completely different, characteristic deposits of protein aggregates (huntingtin and α-synuclein resp.), are a common feature in both diseases. After these observations, many studies are performed with both proteins. Some of them try to understand the nature and driving forces of the aggregation process; others try to find a correlation between the genetic and failure in protein function. Finally with the combination of both approaches, it was proposed that possible strategies deal with pathologic aggregation. Unfortunately, if protein aggregation is a cause or a consequence of the neurodegeneration observed in these pathologies, it is still debatable. This paper describes the process of aggregation of two proteins: huntingtin and α synuclein. The characteristics of the aggregation reaction of these proteins have been followed with novel methods both in vivo and in vitro; these studies include both the combination with other proteins and the presence of various chemical compounds. The ultimate goal of this study was to summarize recent findings on protein aggregation and its possible role as a therapeutic target in neurodegenerative diseases and their role in biomaterial science.
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27
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Chondrogianni N, Gonos ES. Structure and Function of the Ubiquitin–Proteasome System. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 109:41-74. [DOI: 10.1016/b978-0-12-397863-9.00002-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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28
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Fiumara F, Fioriti L, Kandel ER, Hendrickson WA. Essential role of coiled coils for aggregation and activity of Q/N-rich prions and PolyQ proteins. Cell 2011; 143:1121-35. [PMID: 21183075 DOI: 10.1016/j.cell.2010.11.042] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 08/23/2010] [Accepted: 11/16/2010] [Indexed: 11/19/2022]
Abstract
The functional switch of glutamine/asparagine (Q/N)-rich prions and the neurotoxicity of polyQ-expanded proteins involve complex aggregation-prone structural transitions, commonly presumed to be forming β sheets. By analyzing sequences of interaction partners of these proteins, we discovered a recurrent presence of coiled-coil domains both in the partners and in segments that flank or overlap Q/N-rich and polyQ domains. Since coiled coils can mediate protein interactions and multimerization, we studied their possible involvement in Q/N-rich and polyQ aggregations. Using circular dichroism and chemical crosslinking, we found that Q/N-rich and polyQ peptides form α-helical coiled coils in vitro and assemble into multimers. Using structure-guided mutagenesis, we found that coiled-coil domains modulate in vivo properties of two Q/N-rich prions and polyQ-expanded huntingtin. Mutations that disrupt coiled coils impair aggregation and activity, whereas mutations that enhance coiled-coil propensity promote aggregation. These findings support a coiled-coil model for the functional switch of Q/N-rich prions and for the pathogenesis of polyQ-expansion diseases.
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Affiliation(s)
- Ferdinando Fiumara
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
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29
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Guest WC, Silverman JM, Pokrishevsky E, O'Neill MA, Grad LI, Cashman NR. Generalization of the prion hypothesis to other neurodegenerative diseases: an imperfect fit. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:1433-1459. [PMID: 22043906 DOI: 10.1080/15287394.2011.618967] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Protein misfolding diseases have been classically understood as diffuse errors in protein folding, with misfolded protein arising autonomously throughout a tissue due to a pathologic stressor. The field of prion science has provided an alternative mechanism whereby a seed of pathologically misfolded protein, arising exogenously or through a rare endogenous structural fluctuation, yields a template to catalyze misfolding of the native protein. The misfolded protein may then spread intercellularly to communicate the misfold to adjacent areas and ultimately infect a whole tissue. Mounting evidence implicates a prion-like process in the propagation of several neurodegenerative diseases, including Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis, and the tauopathies. However, the parallels between the events observed in these conditions and those in prion disease are often incomplete. The aim of this review was to examine the current state of knowledge concerning the mechanisms of protein misfolding and aggregation for neurodegeneration-associated proteins. In addition, possible methods of intercellular spread are described that focus on the hypothesis that released microvesicles function as misfolded protein delivery vehicles, and the therapeutic options enabled by viewing these diseases from the prion perspective.
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Affiliation(s)
- Will C Guest
- Brain Research Centre, University of British Columbia, Vancouver, BC, Canada
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Mallik M, Lakhotia SC. Modifiers and mechanisms of multi-system polyglutamine neurodegenerative disorders: lessons from fly models. J Genet 2010; 89:497-526. [DOI: 10.1007/s12041-010-0072-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Gallastegui N, Groll M. The 26S proteasome: assembly and function of a destructive machine. Trends Biochem Sci 2010; 35:634-42. [PMID: 20541423 DOI: 10.1016/j.tibs.2010.05.005] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 05/06/2010] [Accepted: 05/11/2010] [Indexed: 11/29/2022]
Abstract
The heart of the ubiquitin-mediated degradation pathway, the 26S proteasome, endoproteolytically cleaves most intracellular proteins, thereby maintaining biological homeostasis and regulating many crucial processes in the cell. This hydrolyzing machine comprises more than 30 different subunits, which perform different functions including the recognition, unfolding, translocating and cleavage of protein substrates. Thus, careful assemblage and regulation of the 26S proteasome is essential to ensure correct positioning and function of each subunit, thereby preserving the delicate cellular balance between protein synthesis and degradation. Here, we review the most current research on the 26S proteasome assembly pathway, and describe the mechanism used by the cell to manage the complex structure and functions of the proteasome.
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Affiliation(s)
- Nerea Gallastegui
- Center for Integrated Protein Science at the Department Chemie, Lehrstuhl für Biochemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
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Münch C, Bertolotti A. Exposure of hydrophobic surfaces initiates aggregation of diverse ALS-causing superoxide dismutase-1 mutants. J Mol Biol 2010; 399:512-25. [PMID: 20399791 PMCID: PMC2927901 DOI: 10.1016/j.jmb.2010.04.019] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 04/12/2010] [Accepted: 04/13/2010] [Indexed: 11/09/2022]
Abstract
The copper-zinc superoxide dismutase-1 (SOD1) is a highly structured protein and, a priori, one of the least likely proteins to be involved in a misfolding disease. However, more than 140, mostly missense, mutations in the SOD1 gene cause aggregation of the affected protein in familial forms of amyotrophic lateral sclerosis (ALS). The remarkable diversity of the effects of these mutations on SOD1 properties has suggested that they promote aggregation by a variety of mechanisms. Experimental assessment of surface hydrophobicity using a sensitive fluorescent-based assay, revealed that diverse ALS-causing mutations provoke SOD1 aggregation by increasing their propensity to expose hydrophobic surfaces. These findings could not be anticipated from analysis of the amino acid sequence. Our results uncover the biochemical nature of the misfolded aggregation-prone intermediate and reconcile the seemingly diverse effects of ALS-causing mutations into a unifying mechanism. Furthermore, the method we describe here will be useful for investigating and interfering with aggregation of various proteins and thereby provide insight into the molecular mechanisms underlying many neurodegenerative diseases.
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Affiliation(s)
- Christian Münch
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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von Mikecz A. PolyQ fibrillation in the cell nucleus: who's bad? Trends Cell Biol 2009; 19:685-91. [PMID: 19796946 DOI: 10.1016/j.tcb.2009.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 08/17/2009] [Accepted: 09/01/2009] [Indexed: 10/20/2022]
Abstract
Nuclear inclusions that contain proteins with expanded polyglutamine (polyQ) repeats are observed in neurodegenerative aggregation diseases and are, therefore, viewed as a pathologic feature. However, a summary of research indicates that polyQ repeats are inherently both toxic and functional at the same time. PolyQ motifs occur in proteins involved in gene expression and promote nuclear assemblies such as the transcription initiation complex. Transition of these functional complexes to insoluble protein aggregates is constitutively prevented by proteasomal proteolysis. Thus, conditions that exhaust the ubiquitin-proteasome system, such as the extensive production of expanded polyQ proteins, aging and xenobiotic stress, induce a congested state in which nuclear proteins, including those with polyQ stretches, form amyloid-like aggregates. Because protein aggregation is preceded by a series of protein misfolding steps termed polyQ fibrillation, the characterization of distinct fibrillation steps correlating with nuclear function and identification of the respective genetic modifiers is essential for understanding both the biology and pathology of polyQ. Thus, the comprehension of the physiological role of polyQ repeats is a prerequisite for uncovering the underlying mechanisms of neurodegenerative aggregation diseases.
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Affiliation(s)
- Anna von Mikecz
- Institut für umweltmedizinische Forschung (IUF) at Heinrich-Heine-University Düsseldorf, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
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Douglas PM, Summers DW, Cyr DM. Molecular chaperones antagonize proteotoxicity by differentially modulating protein aggregation pathways. Prion 2009; 3:51-8. [PMID: 19421006 DOI: 10.4161/pri.3.2.8587] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The self-association of misfolded or damaged proteins into ordered amyloid-like aggregates characterizes numerous neurodegenerative disorders. Insoluble amyloid plaques are diagnostic of many disease states. Yet soluble, oligomeric intermediates in the aggregation pathway appear to represent the toxic culprit. Molecular chaperones regulate the fate of misfolded proteins and thereby influence their aggregation state. Chaperones conventionally antagonize aggregation of misfolded, disease proteins and assist in refolding or degradation pathways. Recent work suggests that chaperones may also suppress neurotoxicity by converting toxic, soluble oligomers into benign aggregates. Chaperones can therefore suppress or promote aggregation of disease proteins to ameliorate the proteotoxic accumulation of soluble, assembly intermediates.
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Affiliation(s)
- Peter M Douglas
- Department of Cell and Developmental Biology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7090, USA
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