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Pluciennik A, Liu Y, Molotsky E, Marsh GB, Ranxhi B, Arnold FJ, St.-Cyr S, Davidson B, Pourshafie N, Lieberman AP, Gu W, Todi SV, Merry DE. Deubiquitinase USP7 contributes to the pathogenicity of spinal and bulbar muscular atrophy. J Clin Invest 2021; 131:134565. [PMID: 33170804 PMCID: PMC7773404 DOI: 10.1172/jci134565] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 10/29/2020] [Indexed: 12/24/2022] Open
Abstract
Polyglutamine (polyQ) diseases are devastating, slowly progressing neurodegenerative conditions caused by expansion of polyQ-encoding CAG repeats within the coding regions of distinct, unrelated genes. In spinal and bulbar muscular atrophy (SBMA), polyQ expansion within the androgen receptor (AR) causes progressive neuromuscular toxicity, the molecular basis of which is unclear. Using quantitative proteomics, we identified changes in the AR interactome caused by polyQ expansion. We found that the deubiquitinase USP7 preferentially interacts with polyQ-expanded AR and that lowering USP7 levels reduced mutant AR aggregation and cytotoxicity in cell models of SBMA. Moreover, USP7 knockdown suppressed disease phenotypes in SBMA and spinocerebellar ataxia type 3 (SCA3) fly models, and monoallelic knockout of Usp7 ameliorated several motor deficiencies in transgenic SBMA mice. USP7 overexpression resulted in reduced AR ubiquitination, indicating the direct action of USP7 on AR. Using quantitative proteomics, we identified the ubiquitinated lysine residues on mutant AR that are regulated by USP7. Finally, we found that USP7 also differentially interacts with mutant Huntingtin (HTT) protein in striatum and frontal cortex of a knockin mouse model of Huntington's disease. Taken together, our findings reveal a critical role for USP7 in the pathophysiology of SBMA and suggest a similar role in SCA3 and Huntington's disease.
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Affiliation(s)
- Anna Pluciennik
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Yuhong Liu
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Elana Molotsky
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Gregory B. Marsh
- Department of Pharmacology and Neurology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Bedri Ranxhi
- Department of Pharmacology and Neurology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Frederick J. Arnold
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Sophie St.-Cyr
- Department of Pathology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Beverly Davidson
- Department of Pathology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Naemeh Pourshafie
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
- George Washington University, Institute of Biomedical Sciences, Washington, DC, USA
| | - Andrew P. Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Wei Gu
- Department of Pathology and Cell Biology and Institute for Cancer Genetics, Columbia University, New York, New York, USA
| | - Sokol V. Todi
- Department of Pharmacology and Neurology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Diane E. Merry
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Abstract
Polyglutamine diseases are hereditary degenerative disorders of the nervous system that have remained, to this date, untreatable. Promisingly, investigation into their molecular etiology and the development of increasingly perfected tools have contributed to the design of novel strategies with therapeutic potential. Encouraging studies have explored gene therapy as a means to counteract cell demise and loss in this context. The current chapter addresses the two main focuses of research in the area: the characteristics of the systems used to deliver nucleic acids to cells and the molecular and cellular actions of the therapeutic agents. Vectors used in gene therapy have to satisfyingly reach the tissues and cell types of interest, while eliciting the lowest toxicity possible. Both viral and non-viral systems have been developed for the delivery of nucleic acids to the central nervous system, each with its respective advantages and shortcomings. Since each polyglutamine disease is caused by mutation of a single gene, many gene therapy strategies have tried to halt degeneration by silencing the corresponding protein products, usually recurring to RNA interference. The potential of small interfering RNAs, short hairpin RNAs and microRNAs has been investigated. Overexpression of protective genes has also been evaluated as a means of decreasing mutant protein toxicity and operate beneficial alterations. Recent gene editing tools promise yet other ways of interfering with the disease-causing genes, at the most upstream points possible. Results obtained in both cell and animal models encourage further delving into this type of therapeutic strategies and support the future use of gene therapy in the treatment of polyglutamine diseases.
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Thorn D, Kay J, Rhazi N, Dumoulin M, Corazza A, Damblon C. 1H, 13C and 15N backbone resonance assignments of the β-lactamase BlaP from Bacillus licheniformis 749/C and two mutational variants. BIOMOLECULAR NMR ASSIGNMENTS 2018; 12:69-77. [PMID: 29030803 DOI: 10.1007/s12104-017-9782-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/18/2017] [Indexed: 06/07/2023]
Abstract
Class A β-lactamases have been widely used as versatile scaffolds to create hybrid (or chimeric) proteins for a series of applications ranging from basic research to medicine. We have, in particular, used the β-lactamase BlaP from Bacillus licheniformis 749/C (BlaP) as a protein scaffold to create model polyglutamine (polyQ) proteins in order to better understand the mechanism(s) by which an expanded polyQ sequence triggers the formation of amyloid fibrils. The model chimeras were designed by inserting a polyQ sequence of various lengths at two different locations within BlaP (i.e. position 197 or position 216) allowing a detailed comparison of the effects of subtle differences in the environment of the polyQ sequence on its ability to trigger protein aggregation. In order to investigate the effects of the polyQ insertion at both positions on the structure, stability and dynamics of BlaP, a series of NMR experiments including H/D exchange are foreseen. Accordingly, as necessitated by these studies, here we report the NMR assignment of the wild-type BlaP (BlaP-WT) and of the two reference proteins, BlaP197Q0 and BlaP216Q0, wherein a Pro-Gly dipeptide has been introduced at position 197 and 216, respectively; this dipeptide originates from the addition of the Sma1 restriction site at the genetic level to allow further polyQ sequence insertion.
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Affiliation(s)
- David Thorn
- Laboratory of Enzymology and Protein Folding, Center for Protein Engineering, InBios, University of Liège, Allée du Six Août 13, Sart-Tilman, 4000, Liège, Belgium
- Research School of Chemistry, The Australian National University, Acton, ACT, 2601, Australia
| | - Jennifer Kay
- Laboratory of Enzymology and Protein Folding, Center for Protein Engineering, InBios, University of Liège, Allée du Six Août 13, Sart-Tilman, 4000, Liège, Belgium
| | - Noureddine Rhazi
- Laboratory of Enzymology and Protein Folding, Center for Protein Engineering, InBios, University of Liège, Allée du Six Août 13, Sart-Tilman, 4000, Liège, Belgium
- Molecular Biomimetic and Protein Engineering Laboratory, GIGA-Research, University of Liège, Quartier Hôpital, avenue de l'Hopital 1, Sart-Tilman, 4000, Liège, Belgium
| | - Mireille Dumoulin
- Laboratory of Enzymology and Protein Folding, Center for Protein Engineering, InBios, University of Liège, Allée du Six Août 13, Sart-Tilman, 4000, Liège, Belgium
| | - Alessandra Corazza
- Department of Medicine, University of Udine, Piazzale Kolbe, 4, 33100, Udine, Italy.
| | - Christian Damblon
- Laboratory of Biological Structural Chemistry, Department of Chemistry, University of Liège, Allée du Six Août 13, Sart-Tilman, 4000, Liège, Belgium.
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Mier P, Andrade-Navarro MA. Glutamine Codon Usage and polyQ Evolution in Primates Depend on the Q Stretch Length. Genome Biol Evol 2018; 10:816-825. [PMID: 29608721 PMCID: PMC5841385 DOI: 10.1093/gbe/evy046] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2018] [Indexed: 12/16/2022] Open
Abstract
Amino acid usage in a proteome depends mostly on its taxonomy, as it does the codon usage in transcriptomes. Here, we explore the level of variation in the codon usage of a specific amino acid, glutamine, in relation to the number of consecutive glutamine residues. We show that CAG triplets are consistently more abundant in short glutamine homorepeats (polyQ, four to eight residues) than in shorter glutamine stretches (one to three residues), leading to the evolutionary growth of the repeat region in a CAG-dependent manner. The length of orthologous polyQ regions is mostly stable in primates, particularly the short ones. Interestingly, given a short polyQ the CAG usage is higher in unstable-in-length orthologous polyQ regions. This indicates that CAG triplets produce the necessary instability for a glutamine stretch to grow. Proteins related to polyQ-associated diseases behave in a more extreme way, with longer glutamine stretches in human and evolutionarily closer nonhuman primates, and an overall higher CAG usage. In the light of our results, we suggest an evolutionary model to explain the glutamine codon usage in polyQ regions.
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Affiliation(s)
- Pablo Mier
- Faculty of Biology, Johannes Gutenberg University Mainz, Germany
- Institute of Molecular Biology, Mainz, Germany
| | - Miguel A Andrade-Navarro
- Faculty of Biology, Johannes Gutenberg University Mainz, Germany
- Institute of Molecular Biology, Mainz, Germany
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Van Assche R, Borghgraef C, Vaneyck J, Dumoulin M, Schoofs L, Temmerman L. In vitro aggregating β-lactamase-polyQ chimeras do not induce toxic effects in an in vivo Caenorhabditis elegans model. J Negat Results Biomed 2017; 16:14. [PMID: 28830560 PMCID: PMC5568214 DOI: 10.1186/s12952-017-0080-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 08/14/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND A series of human diseases are caused by the misfolding and aggregation of specific proteins or peptides into amyloid fibrils; nine of these diseases, referred to as polyglutamine diseases, are associated with proteins carrying an expanded polyglutamine (polyQ) region. While the presence of this latter is thought to be the determinant factor for the development of polyQ diseases, the non-polyQ regions of the host proteins are thought to play a significant modulating role. METHOD In order to better understand the role of non-polyQ regions, the toxic effects of model proteins bearing different polyQ regions (containing up to 79 residues) embedded at two distinct locations within the β-lactamase (BlaP) host enzyme were evaluated in Caenorhabditis elegans. This small organism can be advantageous for the validation of in vitro findings, as it provides a multicellular context yet avoids the typical complexity of common studies relying on vertebrate models. Several phenotypic assays were performed in order to screen for potential toxic effects of the different BlaP-polyQ proteins. RESULTS Despite the significant in vitro aggregation of BlaP-polyQ proteins with long polyQ regions, none of the BlaP-polyQ chimeras aggregated in the generated transgenic in vivo models. CONCLUSION The absence of a toxic effect of the expression of BlaP-polyQ chimeras may find its cause in biochemical mechanisms present in vivo to cope with protein aggregation (e.g. presence of chaperones) or in C. elegans' limitations such as its short lifespan. It is plausible that the aggregation propensities of the different BlaP chimeras containing embedded polyQ sequences are too low in this in vivo environment to permit their aggregation. These experiments emphasize the need for several comparative and in vivo verification studies of biologically relevant in vitro findings, which reveal both the strengths and limitations of widely used model systems.
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Affiliation(s)
- Roel Van Assche
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Zoological Institute, Naamsestraat 59, 3000 Leuven, Belgium
| | - Charline Borghgraef
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Zoological Institute, Naamsestraat 59, 3000 Leuven, Belgium
| | - Jonathan Vaneyck
- Enzymology and Protein Folding, Center for Protein Engineering, InBioS, Institute of Chemistry, University of Liège, Sart-Tilman, 4000 Liège, Belgium
| | - Mireille Dumoulin
- Enzymology and Protein Folding, Center for Protein Engineering, InBioS, Institute of Chemistry, University of Liège, Sart-Tilman, 4000 Liège, Belgium
| | - Liliane Schoofs
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Zoological Institute, Naamsestraat 59, 3000 Leuven, Belgium
| | - Liesbet Temmerman
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Zoological Institute, Naamsestraat 59, 3000 Leuven, Belgium
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Burra G, Thakur AK. Inhibition of polyglutamine aggregation by SIMILAR huntingtin N-terminal sequences: Prospective molecules for preclinical evaluation in Huntington's disease. Biopolymers 2017; 108. [DOI: 10.1002/bip.23021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 04/03/2017] [Accepted: 04/07/2017] [Indexed: 02/06/2023]
Affiliation(s)
- Gunasekhar Burra
- Department of Biological Sciences and Bioengineering; Indian Institute of Technology Kanpur; Kanpur 208016 India
| | - Ashwani Kumar Thakur
- Department of Biological Sciences and Bioengineering; Indian Institute of Technology Kanpur; Kanpur 208016 India
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Wen J, Scoles DR, Facelli JC. Molecular dynamics analysis of the aggregation propensity of polyglutamine segments. PLoS One 2017; 12:e0178333. [PMID: 28542401 PMCID: PMC5444867 DOI: 10.1371/journal.pone.0178333] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 05/11/2017] [Indexed: 01/09/2023] Open
Abstract
Protein misfolding and aggregation is a pathogenic feature shared among at least ten polyglutamine (polyQ) neurodegenerative diseases. While solvent-solution interaction is a key factor driving protein folding and aggregation, the solvation properties of expanded polyQ tracts are not well understood. By using GPU-enabled all-atom molecular dynamics simulations of polyQ monomers in an explicit solvent environment, this study shows that solvent-polyQ interaction propensity decreases as the lengths of polyQ tract increases. This study finds a predominance in long-distance interactions between residues far apart in polyQ sequences with longer polyQ segments, that leads to significant conformational differences. This study also indicates that large loops, comprised of parallel β-structures, appear in long polyQ tracts and present new aggregation building blocks with aggregation driven by long-distance intra-polyQ interactions. Finally, consistent with previous observations using coarse-grain simulations, this study demonstrates that there is a gain in the aggregation propensity with increased polyQ length, and that this gain is correlated with decreasing ability of solvent-polyQ interaction. These results suggest the modulation of solvent-polyQ interactions as a possible therapeutic strategy for treating polyQ diseases.
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Affiliation(s)
- Jingran Wen
- Department of Biomedical Informatics, University of Utah, Salt Lake City, Utah, United States of America
| | - Daniel R. Scoles
- Department of Neurology, University of Utah, Salt Lake City, Utah, United States of America
| | - Julio C. Facelli
- Department of Biomedical Informatics, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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Grasso G, Tuszynski JA, Morbiducci U, Licandro G, Danani A, Deriu MA. Thermodynamic and kinetic stability of the Josephin Domain closed arrangement: evidences from replica exchange molecular dynamics. Biol Direct 2017; 12:2. [PMID: 28103906 PMCID: PMC5244572 DOI: 10.1186/s13062-016-0173-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 12/21/2016] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Molecular phenomena driving pathological aggregation in neurodegenerative diseases are not completely understood yet. Peculiar is the case of Spinocerebellar Ataxia 3 (SCA3) where the conformational properties of the AT-3 N-terminal region, also called Josephin Domain (JD), play a key role in the first step of aggregation, having the JD an amyloidogenic propensity itself. For this reason, unraveling the intimate relationship between JD structural features and aggregation tendency may lead to a step forward in understanding the pathology and rationally design a cure. In this connection, computational modeling has demonstrated to be helpful in exploring the protein molecular dynamics and mechanism of action. RESULTS Conformational dynamics of the JD is here finely investigated by replica exchange molecular dynamics simulations able to sample the microsecond time scale and to provide both a thermodynamic and kinetic description of the protein conformational changes. Accessible structural conformations of the JD have been identified in: open, intermediate and closed like arrangement. Data indicated the closed JD arrangement as the most likely protein arrangement. The protein transition from closed toward intermediate/open states was characterized by a rate constant higher than 700 ns. This result also explains the inability of classical molecular dynamics to explore transitions from closed to open JD configuration on a time scale of hundreds of nanoseconds. CONCLUSION This work provides the first kinetic estimation of the JD transition pathway from open-like to closed-like arrangement and vice-versa, indicating the closed-like arrangement as the most likely configuration for a JD in water environment. More widely, the importance of our results is also underscored considering that the ability to provide a kinetic description of the protein conformational changes is a scientific challenge for both experimental and theoretical approaches to date. REVIEWERS This article was reviewed by Oliviero Carugo, Bojan Zagrovic.
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Affiliation(s)
- Gianvito Grasso
- Istituto Dalle Molle di studi sull’Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera italiana (USI), Centro Galleria 2, Manno, CH-6928 Switzerland
| | - Jack A. Tuszynski
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | | | - Ginevra Licandro
- Istituto Dalle Molle di studi sull’Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera italiana (USI), Centro Galleria 2, Manno, CH-6928 Switzerland
| | - Andrea Danani
- Istituto Dalle Molle di studi sull’Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera italiana (USI), Centro Galleria 2, Manno, CH-6928 Switzerland
| | - Marco A. Deriu
- Istituto Dalle Molle di studi sull’Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera italiana (USI), Centro Galleria 2, Manno, CH-6928 Switzerland
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Deriu MA, Grasso G, Tuszynski JA, Gallo D, Morbiducci U, Danani A. Josephin Domain Structural Conformations Explored by Metadynamics in Essential Coordinates. PLoS Comput Biol 2016; 12:e1004699. [PMID: 26745628 PMCID: PMC4706304 DOI: 10.1371/journal.pcbi.1004699] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 12/09/2015] [Indexed: 01/03/2023] Open
Abstract
The Josephin Domain (JD), i.e. the N-terminal domain of Ataxin 3 (At3) protein, is an interesting example of competition between physiological function and aggregation risk. In fact, the fibrillogenesis of Ataxin 3, responsible for the spinocerebbellar ataxia 3, is strictly related to the JD thermodynamic stability. Whereas recent NMR studies have demonstrated that different JD conformations exist, the likelihood of JD achievable conformational states in solution is still an open issue. Marked differences in the available NMR models are located in the hairpin region, supporting the idea that JD has a flexible hairpin in dynamic equilibrium between open and closed states. In this work we have carried out an investigation on the JD conformational arrangement by means of both classical molecular dynamics (MD) and Metadynamics employing essential coordinates as collective variables. We provide a representation of the free energy landscape characterizing the transition pathway from a JD open-like structure to a closed-like conformation. Findings of our in silico study strongly point to the closed-like conformation as the most likely for a Josephin Domain in water.
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Affiliation(s)
- Marco A. Deriu
- Istituto Dalle Molle di studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera italiana (USI), Manno, Switzerland
- * E-mail:
| | - Gianvito Grasso
- Istituto Dalle Molle di studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera italiana (USI), Manno, Switzerland
| | - Jack A. Tuszynski
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada
| | - Diego Gallo
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino, Italy
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino, Italy
| | - Andrea Danani
- Istituto Dalle Molle di studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera italiana (USI), Manno, Switzerland
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Lupton CJ, Steer DL, Wintrode PL, Bottomley SP, Hughes VA, Ellisdon AM. Enhanced molecular mobility of ordinarily structured regions drives polyglutamine disease. J Biol Chem 2015; 290:24190-200. [PMID: 26260925 DOI: 10.1074/jbc.m115.659532] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Indexed: 01/09/2023] Open
Abstract
Polyglutamine expansion is a hallmark of nine neurodegenerative diseases, with protein aggregation intrinsically linked to disease progression. Although polyglutamine expansion accelerates protein aggregation, the misfolding process is frequently instigated by flanking domains. For example, polyglutamine expansion in ataxin-3 allosterically triggers the aggregation of the catalytic Josephin domain. The molecular mechanism that underpins this allosteric aggregation trigger remains to be determined. Here, we establish that polyglutamine expansion increases the molecular mobility of two juxtaposed helices critical to ataxin-3 deubiquitinase activity. Within one of these helices, we identified a highly amyloidogenic sequence motif that instigates aggregation and forms the core of the growing fibril. Critically, by mutating residues within this key region, we decrease local structural fluctuations to slow ataxin-3 aggregation. This provides significant insight, down to the molecular level, into how polyglutamine expansion drives aggregation and explains the positive correlation between polyglutamine tract length, protein aggregation, and disease severity.
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Affiliation(s)
- Christopher J Lupton
- From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and
| | - David L Steer
- From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and
| | - Patrick L Wintrode
- the Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201
| | - Stephen P Bottomley
- From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and
| | - Victoria A Hughes
- From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and the Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia, 3800 and
| | - Andrew M Ellisdon
- From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and the Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia, 3800 and
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Almeida B, Abreu IA, Matos CA, Fraga JS, Fernandes S, Macedo MG, Gutiérrez-Gallego R, Pereira PJB, Carvalho AL, Macedo-Ribeiro S. SUMOylation of the brain-predominant Ataxin-3 isoform modulates its interaction with p97. Biochim Biophys Acta Mol Basis Dis 2015; 1852:1950-9. [PMID: 26073430 DOI: 10.1016/j.bbadis.2015.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 05/12/2015] [Accepted: 06/08/2015] [Indexed: 11/18/2022]
Abstract
BACKGROUND Machado-Joseph Disease (MJD), a form of dominantly inherited ataxia belonging to the group of polyQ expansion neurodegenerative disorders, occurs when a threshold value for the number of glutamines in Ataxin-3 (Atx3) polyglutamine region is exceeded. As a result of its modular multidomain architecture, Atx3 is known to engage in multiple macromolecular interactions, which might be unbalanced when the polyQ tract is expanded, culminating in the aggregation and formation of intracellular inclusions, a unifying fingerprint of this group of neurodegenerative disorders. Since aggregation is specific to certain brain regions, localization-dependent posttranslational modifications that differentially affect Atx3 might also contribute for MJD. METHODS We combined in vitro and cellular approaches to address SUMOylation in the brain-predominant Atx3 isoform and assessed the impact of this posttranslational modification on Atx3 self-assembly and interaction with its native partner, p97. RESULTS We demonstrate that Atx3 is SUMOylated at K356 both in vitro and in cells, which contributes for decreased formation of amyloid fibrils and for increased affinity towards p97. CONCLUSIONS AND GENERAL SIGNIFICANCE These findings highlight the role of SUMOylation as a regulator of Atx3 function, with implications on Atx3 protein interaction network and self-assembly, with potential impact for further understanding the molecular mechanisms underlying MJD pathogenesis.
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Affiliation(s)
- Bruno Almeida
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Isabel A Abreu
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Carlos A Matos
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Joana S Fraga
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Sara Fernandes
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Maria G Macedo
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Ricardo Gutiérrez-Gallego
- Bioanalysis Group, Neurosciences Research Program, Hospital del Mar Medical Research Institute (IMIM)-Parque de Salud Mar, 08003 Barcelona, Spain; Department of Experimental and Health Sciences, Pompeu Fabra University, 08003 Barcelona, Spain
| | - Pedro José Barbosa Pereira
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Ana Luísa Carvalho
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Sandra Macedo-Ribeiro
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal.
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12
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Age-, tissue- and length-dependent bidirectional somatic CAG•CTG repeat instability in an allelic series of R6/2 Huntington disease mice. Neurobiol Dis 2015; 76:98-111. [PMID: 25662336 DOI: 10.1016/j.nbd.2015.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/30/2014] [Accepted: 01/25/2015] [Indexed: 12/11/2022] Open
Abstract
The expansion of simple sequence CAG•CTG repeats is associated with a number of inherited disorders including Huntington disease (HD), myotonic dystrophy type 1 and several of the spinocerebellar ataxias. Inherited disease-associated alleles usually exceed 40 repeats and may be in excess of 1,000 repeats in some disorders. Inherited allele length is inversely proportional to age at onset, and frequent germline expansions account for the striking anticipation observed in affected families. Expanded disease associated alleles are also somatically unstable via a pathway that is age dependent and tissue specific, and also appears to be expansion biased. Somatic expansions are thought to contribute toward both tissue specificity and disease progression. Here we have examined the somatic mutational dynamics in brain and peripheral tissues from an allelic series of R6/2 HD transgenic mice inheriting from 52 to >700 CAG repeats. We found age-dependent, tissue-specific somatic instability, with particularly large expansions observed in the striatum and cortex. We also found a positive increase in somatic instability with increasing allele length. Surprisingly, however, the degree of somatic variation did not increase in a linear fashion, but leveled off with increasing allele length. Most unexpectedly, the almost exclusive bias toward the accumulation of expansions observed in mice inheriting smaller alleles was lost, and a high frequency of large somatic contractions was observed in mice inheriting very large alleles (>500 repeats). These data highlight the bidirectional nature of CAG•CTG repeat instability and the subtle balance that exists between expansion and contraction in vivo. Defining the dynamics and tissue specificity of expansion and contraction is important for understanding the role of genetic instability in pathophysiology and in particular the development of novel therapies based on suppressing expansions and/or promoting contractions.
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Huynen C, Willet N, Buell AK, Duwez AS, Jerôme C, Dumoulin M. Influence of the protein context on the polyglutamine length-dependent elongation of amyloid fibrils. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1854:239-48. [PMID: 25489872 DOI: 10.1016/j.bbapap.2014.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/20/2014] [Accepted: 12/01/2014] [Indexed: 12/24/2022]
Abstract
Polyglutamine (polyQ) diseases, including Huntington's disease, are neurodegenerative disorders associated with the abnormal expansion of a polyQ tract within nine proteins. The polyQ expansion is thought to be a major determinant in the development of neurotoxicity, triggering protein aggregation into amyloid fibrils, although non-polyQ regions play a modulating role. In this work, we investigate the relative importance of the polyQ length, its location within a host protein, and the conformational state of the latter in the amyloid fibril elongation. Model polyQ proteins made of the β-lactamase BlaP containing up to 79Q inserted at two different positions, and quartz crystal microbalance and atomic force microscopy were used for this purpose. We demonstrate that, independently of the polyQ tract location and the conformational state of the host protein, the relative elongation rate of fibrils increases linearly with the polyQ length. The slope of the linear fit is similar for both sets of chimeras (i.e., the elongation rate increases by ~1.9% for each additional glutamine), and is also similar to that previously observed for polyQ peptides. The elongation rate is, however, strongly influenced by the location of the polyQ tract within BlaP and the conformational state of BlaP. Moreover, comparison of our results with those previously reported for aggregation in solution indicates that these two parameters also modulate the ability of BlaP-polyQ chimeras to form the aggregation nucleus. Altogether our results suggest that non-polyQ regions are valuable targets in order to interfere with the process of amyloid fibril formation associated with polyQ diseases.
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Affiliation(s)
- Céline Huynen
- Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, University of Liege, Liege, Belgium
| | - Nicolas Willet
- Nanochemistry and Molecular Systems, Department of Chemistry, University of Liege, Liege, Belgium
| | - Alexander K Buell
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Anne-Sophie Duwez
- Nanochemistry and Molecular Systems, Department of Chemistry, University of Liege, Liege, Belgium
| | - Christine Jerôme
- Center for Education and Research on Macromolecules (CERM), Department of Chemistry, University of Liege, Liege, Belgium
| | - Mireille Dumoulin
- Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, University of Liege, Liege, Belgium.
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Polling S, Mok YF, Ramdzan YM, Turner BJ, Yerbury JJ, Hill AF, Hatters DM. Misfolded polyglutamine, polyalanine, and superoxide dismutase 1 aggregate via distinct pathways in the cell. J Biol Chem 2014; 289:6669-6680. [PMID: 24425868 DOI: 10.1074/jbc.m113.520189] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Protein aggregation into intracellular inclusions is a key feature of many neurodegenerative disorders. A common theme has emerged that inappropriate self-aggregation of misfolded or mutant polypeptide sequences is detrimental to cell health. Yet protein quality control mechanisms may also deliberately cluster them together into distinct inclusion subtypes, including the insoluble protein deposit (IPOD) and the juxtanuclear quality control (JUNQ). Here we investigated how the intrinsic oligomeric state of three model systems of disease-relevant mutant protein and peptide sequences relates to the IPOD and JUNQ patterns of aggregation using sedimentation velocity analysis. Two of the models (polyalanine (37A) and superoxide dismutase 1 (SOD1) mutants A4V and G85R) accumulated into the same JUNQ-like inclusion whereas the other, polyglutamine (72Q), formed spatially distinct IPOD-like inclusions. Using flow cytometry pulse shape analysis (PulSA) to separate cells with inclusions from those without revealed the SOD1 mutants and 37A to have abruptly altered oligomeric states with respect to the nonaggregating forms, regardless of whether cells had inclusions or not, whereas 72Q was almost exclusively monomeric until inclusions formed. We propose that mutations leading to JUNQ inclusions induce a constitutively "misfolded" state exposing hydrophobic side chains that attract and ultimately overextend protein quality capacity, which leads to aggregation into JUNQ inclusions. Poly(Q) is not misfolded in this same sense due to universal polar side chains, but is highly prone to forming amyloid fibrils that we propose invoke a different engagement mechanism with quality control.
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Affiliation(s)
- Saskia Polling
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Yee-Foong Mok
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Yasmin M Ramdzan
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Bradley J Turner
- Florey Institute of Neuroscience and Mental Health and Centre for Neuroscience, The University of Melbourne, Victoria 3010, Australia
| | - Justin J Yerbury
- School of Biological Sciences, Faculty of Science and Illawarra Health and Medical Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Andrew F Hill
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Danny M Hatters
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
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In vivo interaction proteomics reveal a novel p38 mitogen-activated protein kinase/Rack1 pathway regulating proteostasis in Drosophila muscle. Mol Cell Biol 2013; 34:474-84. [PMID: 24277934 DOI: 10.1128/mcb.00824-13] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several recent studies suggest that systemic aging in metazoans is differentially affected by functional decline in specific tissues, such as skeletal muscle. In Drosophila, longevity appears to be tightly linked to myoproteostasis, and the formation of misfolded protein aggregates is a hallmark of senescence in aging muscle. Similarly, defective myoproteostasis is described as an important contributor to the pathology of several age-related degenerative muscle diseases in humans, e.g., inclusion body myositis. p38 mitogen-activated protein kinase (MAPK) plays a central role in a conserved signaling pathway activated by a variety of stressful stimuli. Aging p38 MAPK mutant flies display accelerated motor function decline, concomitant with an enhanced accumulation of detergent-insoluble protein aggregates in thoracic muscles. Chemical genetic experiments suggest that p38-mediated regulation of myoproteostasis is not limited to the control of reactive oxygen species production or the protein degradation pathways but also involves upstream turnover pathways, e.g., translation. Using affinity purification and mass spectrometry, we identified Rack1 as a novel substrate of p38 MAPK in aging muscle and showed that the genetic interaction between p38b and Rack1 controls muscle aggregate formation, locomotor function, and longevity. Biochemical analyses of Rack1 in aging and stressed muscle suggest a model whereby p38 MAPK signaling causes a redistribution of Rack1 between a ribosome-bound pool and a putative translational repressor complex.
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Strnad P, Nuraldeen R, Guldiken N, Hartmann D, Mahajan V, Denk H, Haybaeck J. Broad Spectrum of Hepatocyte Inclusions in Humans, Animals, and Experimental Models. Compr Physiol 2013; 3:1393-436. [DOI: 10.1002/cphy.c120032] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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17
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Krench M, Littleton JT. Modeling Huntington disease in Drosophila: Insights into axonal transport defects and modifiers of toxicity. Fly (Austin) 2013; 7:229-36. [PMID: 24022020 DOI: 10.4161/fly.26279] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Huntington disease (HD) is an inherited neurodegenerative disorder caused by a polyglutamine (polyQ) expansion in the huntingtin (Htt) gene. Despite years of research, there is no treatment that extends life for patients with the disorder. Similarly, little is known about which cellular pathways that are altered by pathogenic Huntingtin (Htt) protein expression are correlated with neuronal loss. As part of a longstanding effort to gain insights into HD pathology, we have been studying the protein in the context of the fruitfly Drosophila melanogaster. We generated transgenic HD models in Drosophila by engineering flies that carry a 12-exon fragment of the human Htt gene with or without the toxic trinucleotide repeat expansion. We also created variants with a monomeric red fluorescent protein (mRFP) tag fused to Htt that allows in vivo imaging of Htt protein localization and aggregation. While wild-type Htt remains diffuse throughout the cytoplasm of cells, pathogenic Htt forms insoluble aggregates that accumulate in neuronal soma and axons. Aggregates can physically block transport of numerous organelles along the axon. We have also observed that aggregates are formed quickly, within just a few hours of mutant Htt expression. To explore mechanisms of neurodegeneration in our HD model, we performed in vivo and in vitro screens to search for modifiers of viability and pathogenic Htt aggregation. Our results identified several novel candidates for HD therapeutics that can now be tested in mammalian models of HD. Furthermore, these experiments have highlighted the complex relationship between aggregates and toxicity that exists in HD.
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Affiliation(s)
- Megan Krench
- The Picower Institute for Learning and Memory; Department of Brain and Cognitive Sciences; Department of Biology; Massachusetts Institute of Technology; Cambridge, MA USA
| | - J Troy Littleton
- The Picower Institute for Learning and Memory; Department of Brain and Cognitive Sciences; Department of Biology; Massachusetts Institute of Technology; Cambridge, MA USA
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18
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Class A β-lactamases as versatile scaffolds to create hybrid enzymes: applications from basic research to medicine. BIOMED RESEARCH INTERNATIONAL 2013; 2013:827621. [PMID: 24066299 PMCID: PMC3771265 DOI: 10.1155/2013/827621] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/04/2013] [Indexed: 01/13/2023]
Abstract
Designing hybrid proteins is a major aspect of protein engineering and covers a very wide range of applications from basic research to medical applications. This review focuses on the use of class A β-lactamases as versatile scaffolds to design hybrid enzymes (referred to as β-lactamase hybrid proteins, BHPs) in which an exogenous peptide, protein or fragment thereof is inserted at various permissive positions. We discuss how BHPs can be specifically designed to create bifunctional proteins, to produce and to characterize proteins that are otherwise difficult to express, to determine the epitope of specific antibodies, to generate antibodies against nonimmunogenic epitopes, and to better understand the structure/function relationship of proteins.
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Saunders HM, Hughes VA, Cappai R, Bottomley SP. Conformational behavior and aggregation of ataxin-3 in SDS. PLoS One 2013; 8:e69416. [PMID: 23894474 PMCID: PMC3718759 DOI: 10.1371/journal.pone.0069416] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/11/2013] [Indexed: 01/08/2023] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) is one of nine polyglutamine (polyQ) diseases all characterized by the presence of intraneuronal inclusions that contain aggregated protein. Aggregation of ataxin-3, the causative protein of SCA3, has been well characterized in vitro, with both pathogenic and non-pathogenic length ataxin-3 undergoing fibrillogenesis. However, only ataxin-3 containing an expanded polyQ tract leads to SCA3. Therefore other cellular factors, not present in previous in vitro studies, may modulate aggregation during disease. The interactions between fibrillar species and cell membranes have been characterized in a number of amyloid diseases, including Huntington’s Disease, and these interactions affect aggregation and toxicity. We have characterized the effects of the membrane mimetic sodium dodecyl sulfate (SDS) on ataxin-3 structure and aggregation, to show that both micellar and non-micellar SDS have differing effects on the two stages of ataxin-3 aggregation. We also demonstrate that fibrillar ataxin-3 binds phospholipids, in particular phosphorylated phosphotidylinositols. These results highlight the effect of intracellular factors on the ataxin-3 misfolding landscape and their implications in SCA3 and polyQ diseases in general are discussed.
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Affiliation(s)
- Helen M. Saunders
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Victoria A. Hughes
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Roberto Cappai
- Department of Pathology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Stephen P. Bottomley
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- * E-mail:
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Blum ES, Schwendeman AR, Shaham S. PolyQ disease: misfiring of a developmental cell death program? Trends Cell Biol 2012; 23:168-74. [PMID: 23228508 DOI: 10.1016/j.tcb.2012.11.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 11/06/2012] [Accepted: 11/12/2012] [Indexed: 12/14/2022]
Abstract
Polyglutamine (polyQ) repeat diseases are neurodegenerative ailments elicited by glutamine-encoding CAG nucleotide expansions within endogenous human genes. Despite efforts to understand the basis of these diseases, the precise mechanism of cell death remains stubbornly unclear. Much of the data seem to be consistent with a model in which toxicity is an inherent property of the polyQ repeat, whereas host protein sequences surrounding the polyQ expansion modulate severity, age of onset, and cell specificity. Recently, a gene, pqn-41, encoding a glutamine-rich protein, was found to promote normally occurring non-apoptotic cell death in Caenorhabditis elegans. Here we review evidence for toxic and modulatory roles for polyQ repeats and their host proteins, respectively, and suggest similarities with pqn-41 function. We explore the hypothesis that toxicity mediated by glutamine-rich motifs may be important not only in pathology, but also in normal development.
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Affiliation(s)
- Elyse S Blum
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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21
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Scarafone N, Pain C, Fratamico A, Gaspard G, Yilmaz N, Filée P, Galleni M, Matagne A, Dumoulin M. Amyloid-like fibril formation by polyQ proteins: a critical balance between the polyQ length and the constraints imposed by the host protein. PLoS One 2012; 7:e31253. [PMID: 22438863 PMCID: PMC3305072 DOI: 10.1371/journal.pone.0031253] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 01/05/2012] [Indexed: 11/18/2022] Open
Abstract
Nine neurodegenerative disorders, called polyglutamine (polyQ) diseases, are characterized by the formation of intranuclear amyloid-like aggregates by nine proteins containing a polyQ tract above a threshold length. These insoluble aggregates and/or some of their soluble precursors are thought to play a role in the pathogenesis. The mechanism by which polyQ expansions trigger the aggregation of the relevant proteins remains, however, unclear. In this work, polyQ tracts of different lengths were inserted into a solvent-exposed loop of the β-lactamase BlaP and the effects of these insertions on the properties of BlaP were investigated by a range of biophysical techniques. The insertion of up to 79 glutamines does not modify the structure of BlaP; it does, however, significantly destabilize the enzyme. The extent of destabilization is largely independent of the polyQ length, allowing us to study independently the effects intrinsic to the polyQ length and those related to the structural integrity of BlaP on the aggregating properties of the chimeras. Only chimeras with 55Q and 79Q readily form amyloid-like fibrils; therefore, similarly to the proteins associated with diseases, there is a threshold number of glutamines above which the chimeras aggregate into amyloid-like fibrils. Most importantly, the chimera containing 79Q forms amyloid-like fibrils at the same rate whether BlaP is folded or not, whereas the 55Q chimera aggregates into amyloid-like fibrils only if BlaP is unfolded. The threshold value for amyloid-like fibril formation depends, therefore, on the structural integrity of the β-lactamase moiety and thus on the steric and/or conformational constraints applied to the polyQ tract. These constraints have, however, no significant effect on the propensity of the 79Q tract to trigger fibril formation. These results suggest that the influence of the protein context on the aggregating properties of polyQ disease-associated proteins could be negligible when the latter contain particularly long polyQ tracts.
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Affiliation(s)
- Natacha Scarafone
- Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - Coralie Pain
- Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - Anthony Fratamico
- Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - Gilles Gaspard
- Biological Macromolecules, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - Nursel Yilmaz
- Biological Macromolecules, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - Patrice Filée
- Biological Macromolecules, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - Moreno Galleni
- Biological Macromolecules, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - André Matagne
- Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
| | - Mireille Dumoulin
- Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, Institute of Chemistry, University of Liège, Liège, Belgium
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Kumar P, Pradhan K, Karunya R, Ambasta RK, Querfurth HW. Cross-functional E3 ligases Parkin and C-terminus Hsp70-interacting protein in neurodegenerative disorders. J Neurochem 2011; 120:350-70. [DOI: 10.1111/j.1471-4159.2011.07588.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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23
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Nestor CE, Monckton DG. Correlation of inter-locus polyglutamine toxicity with CAG•CTG triplet repeat expandability and flanking genomic DNA GC content. PLoS One 2011; 6:e28260. [PMID: 22163004 PMCID: PMC3232215 DOI: 10.1371/journal.pone.0028260] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 11/04/2011] [Indexed: 11/19/2022] Open
Abstract
Dynamic expansions of toxic polyglutamine (polyQ)-encoding CAG repeats in ubiquitously expressed, but otherwise unrelated, genes cause a number of late-onset progressive neurodegenerative disorders, including Huntington disease and the spinocerebellar ataxias. As polyQ toxicity in these disorders increases with repeat length, the intergenerational expansion of unstable CAG repeats leads to anticipation, an earlier age-at-onset in successive generations. Crucially, disease associated alleles are also somatically unstable and continue to expand throughout the lifetime of the individual. Interestingly, the inherited polyQ length mediating a specific age-at-onset of symptoms varies markedly between disorders. It is widely assumed that these inter-locus differences in polyQ toxicity are mediated by protein context effects. Previously, we demonstrated that the tendency of expanded CAG•CTG repeats to undergo further intergenerational expansion (their 'expandability') also differs between disorders and these effects are strongly correlated with the GC content of the genomic flanking DNA. Here we show that the inter-locus toxicity of the expanded polyQ tracts of these disorders also correlates with both the expandability of the underlying CAG repeat and the GC content of the genomic DNA flanking sequences. Inter-locus polyQ toxicity does not correlate with properties of the mRNA or protein sequences, with polyQ location within the gene or protein, or steady state transcript levels in the brain. These data suggest that the observed inter-locus differences in polyQ toxicity are not mediated solely by protein context effects, but that genomic context is also important, an effect that may be mediated by modifying the rate at which somatic expansion of the DNA delivers proteins to their cytotoxic state.
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Affiliation(s)
- Colm E Nestor
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
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24
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Bodai L, Marsh JL. A novel target for Huntington's disease: ERK at the crossroads of signaling. Bioessays 2011; 34:142-8. [DOI: 10.1002/bies.201100116] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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Abstract
Protein misfolding is associated with many human diseases, including neurodegenerative diseases, such as Alzheimer disease, Parkinson disease and Huntington disease. Protein misfolding often results in the formation of intracellular or extracellular inclusions or aggregates. Even though deciphering the role of these aggregates has been the object of intense research activity, their role in protein misfolding diseases is unclear. Here, I discuss the implications of studies on polyglutamine aggregation and toxicity in yeast and other model organisms. These studies provide an excellent experimental and conceptual paradigm that contributes to understanding the differences between toxic and protective trajectories of protein misfolding. Future studies like the ones discussed here have the potential to transform basic concepts of protein misfolding in human diseases and may thus help to identify new therapeutic strategies for their treatment.
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Długosz M, Trylska J. Secondary structures of native and pathogenic huntingtin N-terminal fragments. J Phys Chem B 2011; 115:11597-608. [PMID: 21910495 DOI: 10.1021/jp206373g] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Huntington's disease is a neurodegenerative disorder caused by a polyglutamine (polyQ) expansion in the N-terminal fragment of the Huntingtin (Htt) protein. Structural properties of Htt N-terminal regions and the molecular mechanism leading to protein aggregation have not been fully explained yet. We performed all-atom replica exchange molecular dynamics to investigate the structures of Htt N-terminal parts with polyQ tracts of nonpathogenic and pathogenic lengths. The monomers were composed of the headpiece (17 N-terminal residues), a polyQ tract (polyQ(17) for native and polyQ(55) for pathogenic sequence), and a polyP(11) region, followed by 17 amino acids of mixed sequence. We found that corresponding regions in both fragments fold to similar secondary structures; the headpiece and polyQ stretch adopt mainly α-helical conformations, and polyP(11) forms the PP II-type helix. The native N-terminal fragment is more compact and stabilized by hydrophobic interactions between the surface of polyP(11) and the amphipathic helix of the headpiece. In the pathogenic fragment the headpiece is solvent exposed and does not interact with polyP(11). The predicted structure of the native N-terminal fragment agrees with the X-ray structure of the Htt first exon containing polyQ(17). The structure of the pathogenic fragment adheres to an aggregation model that is mediated by the Htt headpiece.
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Affiliation(s)
- Maciej Długosz
- Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw, Żwirki i Wigury 93, Warsaw 02-089, Poland.
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27
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Jimenez-Sanchez M, Thomson F, Zavodszky E, Rubinsztein DC. Autophagy and polyglutamine diseases. Prog Neurobiol 2011; 97:67-82. [PMID: 21930185 PMCID: PMC3712188 DOI: 10.1016/j.pneurobio.2011.08.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 08/25/2011] [Accepted: 08/30/2011] [Indexed: 01/16/2023]
Abstract
In polyglutamine diseases, an abnormally elongated polyglutamine tract results in protein misfolding and accumulation of intracellular aggregates. The length of the polyglutamine expansion correlates with the tendency of the mutant protein to aggregate, as well as with neuronal toxicity and earlier disease onset. Although currently there is no effective cure to prevent or slow down the progression of these neurodegenerative disorders, increasing the clearance of mutant proteins has been proposed as a potential therapeutic approach. The ubiquitin–proteasome system and autophagy are the two main degradative pathways responsible for eliminating misfolded and unnecessary proteins in the cell. We will review some of the studies that have proposed autophagy as a strategy to reduce the accumulation of polyglutamine-expanded protein aggregates and protect against mutant protein neurotoxicity. We will also discuss some of the currently known mechanisms that induce autophagy, which may be beneficial for the treatment of these and other neurodegenerative disorders.
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28
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Matos CA, de Macedo-Ribeiro S, Carvalho AL. Polyglutamine diseases: The special case of ataxin-3 and Machado–Joseph disease. Prog Neurobiol 2011; 95:26-48. [DOI: 10.1016/j.pneurobio.2011.06.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/06/2011] [Accepted: 06/07/2011] [Indexed: 10/18/2022]
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29
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Schulte J, Sepp KJ, Wu C, Hong P, Littleton JT. High-content chemical and RNAi screens for suppressors of neurotoxicity in a Huntington's disease model. PLoS One 2011; 6:e23841. [PMID: 21909362 PMCID: PMC3166080 DOI: 10.1371/journal.pone.0023841] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 07/26/2011] [Indexed: 11/27/2022] Open
Abstract
To identify Huntington's Disease therapeutics, we conducted high-content small molecule and RNAi suppressor screens using a Drosophila primary neural culture Huntingtin model. Drosophila primary neurons offer a sensitive readout for neurotoxicty, as their neurites develop dysmorphic features in the presence of mutant polyglutamine-expanded Huntingtin compared to nonpathogenic Huntingtin. By tracking the subcellular distribution of mRFP-tagged pathogenic Huntingtin and assaying neurite branch morphology via live-imaging, we identified suppressors that could reduce Huntingtin aggregation and/or prevent the formation of dystrophic neurites. The custom algorithms we used to quantify neurite morphologies in complex cultures provide a useful tool for future high-content screening approaches focused on neurodegenerative disease models. Compounds previously found to be effective aggregation inhibitors in mammalian systems were also effective in Drosophila primary cultures, suggesting translational capacity between these models. However, we did not observe a direct correlation between the ability of a compound or gene knockdown to suppress aggregate formation and its ability to rescue dysmorphic neurites. Only a subset of aggregation inhibitors could revert dysmorphic cellular profiles. We identified lkb1, an upstream kinase in the mTOR/Insulin pathway, and four novel drugs, Camptothecin, OH-Camptothecin, 18β-Glycyrrhetinic acid, and Carbenoxolone, that were strong suppressors of mutant Huntingtin-induced neurotoxicity. Huntingtin neurotoxicity suppressors identified through our screen also restored viability in an in vivo Drosophila Huntington's Disease model, making them attractive candidates for further therapeutic evaluation.
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Affiliation(s)
- Joost Schulte
- Department of Biology, Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
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Saunders HM, Gilis D, Rooman M, Dehouck Y, Robertson AL, Bottomley SP. Flanking domain stability modulates the aggregation kinetics of a polyglutamine disease protein. Protein Sci 2011; 20:1675-81. [PMID: 21780213 DOI: 10.1002/pro.698] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 06/29/2011] [Accepted: 06/30/2011] [Indexed: 11/12/2022]
Abstract
Spinocerebellar Ataxia Type 3 (SCA3) is one of nine polyglutamine (polyQ) diseases that are all characterized by progressive neuronal dysfunction and the presence of neuronal inclusions containing aggregated polyQ protein, suggesting that protein misfolding is a key part of this disease. Ataxin-3, the causative protein of SCA3, contains a globular, structured N-terminal domain (the Josephin domain) and a flexible polyQ-containing C-terminal tail, the repeat-length of which modulates pathogenicity. It has been suggested that the fibrillogenesis pathway of ataxin-3 begins with a non-polyQ-dependent step mediated by Josephin domain interactions, followed by a polyQ-dependent step. To test the involvement of the Josephin domain in ataxin-3 fibrillogenesis, we have created both pathogenic and nonpathogenic length ataxin-3 variants with a stabilized Josephin domain, and have both stabilized and destabilized the isolated Josephin domain. We show that changing the thermodynamic stability of the Josephin domain modulates ataxin-3 fibrillogenesis. These data support the hypothesis that the first stage of ataxin-3 fibrillogenesis is caused by interactions involving the non-polyQ containing Josephin domain and that the thermodynamic stability of this domain is linked to the aggregation propensity of ataxin-3.
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Affiliation(s)
- Helen M Saunders
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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31
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The Josephin domain determines the morphological and mechanical properties of ataxin-3 fibrils. Biophys J 2011; 100:2033-42. [PMID: 21504740 DOI: 10.1016/j.bpj.2011.02.056] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 02/15/2011] [Accepted: 02/25/2011] [Indexed: 12/15/2022] Open
Abstract
Fibrillar aggregation of the protein ataxin-3 is linked to the inherited neurodegenerative disorder Spinocerebellar ataxia type 3, a member of the polyQ expansion disease family. We previously reported that aggregation and stability of the nonpathological form of ataxin-3, carrying an unexpanded polyQ tract, are modulated by its N-terminal Josephin domain. It was also shown that expanded ataxin-3 aggregates via a two-stage mechanism initially involving Josephin self-association, followed by a polyQ-dependent step. Despite this recent progress, however, the exact mechanism of ataxin-3 fibrilization remains elusive. Here, we have used electron microscopy, atomic force microscopy, and other biophysical techniques to characterize the morphological and mechanical properties of nonexpanded ataxin-3 fibrils. By comparing aggregates of ataxin-3 and of the isolated Josephin domain, we show that the two proteins self-assemble into fibrils with markedly similar features over the temperature range 37-50°C. Estimates of persistence length and Young's modulus of the fibrils reveal a great flexibility. Our data indicate that, under physiological conditions, during early aggregation Josephin retains a nativelike secondary structure but loses its enzymatic activity. The results suggest a key role of Josephin in ataxin-3 fibrillar aggregation.
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Sivanandam VN, Jayaraman M, Hoop CL, Kodali R, Wetzel R, van der Wel PCA. The aggregation-enhancing huntingtin N-terminus is helical in amyloid fibrils. J Am Chem Soc 2011; 133:4558-66. [PMID: 21381744 DOI: 10.1021/ja110715f] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The 17-residue N-terminus (htt(NT)) directly flanking the polyQ sequence in huntingtin (htt) N-terminal fragments plays a crucial role in initiating and accelerating the aggregation process that is associated with Huntington's disease pathogenesis. Here we report on magic-angle-spinning solid-state NMR studies of the amyloid-like aggregates of an htt N-terminal fragment. We find that the polyQ portion of this peptide exists in a rigid, dehydrated amyloid core that is structurally similar to simpler polyQ fibrils and may contain antiparallel β-sheets. In contrast, the htt(NT) sequence in the aggregates is composed in part of a well-defined helix, which likely also exists in early oligomeric aggregates. Further NMR experiments demonstrate that the N-terminal helical segment displays increased dynamics and water exposure. Given its specific contribution to the initiation, rate, and mechanism of fibril formation, the helical nature of htt(NT) and its apparent lack of effect on the polyQ fibril core structure seem surprising. The results provide new details about these disease-associated aggregates and also provide a clear example of an amino acid sequence that greatly enhances the rate of amyloid formation while itself not taking part in the amyloid structure. There is an interesting mechanistic analogy to recent reports pointing out the early-stage contributions of transient intermolecular helix-helix interactions in the aggregation behavior of various other amyloid fibrils.
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Affiliation(s)
- V N Sivanandam
- Department of Structural Biology, University of Pittsburgh School of Medicine, Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, Pennsylvania 15260, USA
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Robertson AL, Bate MA, Androulakis SG, Bottomley SP, Buckle AM. PolyQ: a database describing the sequence and domain context of polyglutamine repeats in proteins. Nucleic Acids Res 2010; 39:D272-6. [PMID: 21059684 PMCID: PMC3013692 DOI: 10.1093/nar/gkq1100] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The polyglutamine diseases are caused in part by a gain-of-function mechanism of neuronal toxicity involving protein conformational changes that result in the formation and deposition of β-sheet rich aggregates. Recent evidence suggests that the misfolding mechanism is context-dependent, and that properties of the host protein, including the domain architecture and location of the repeat tract, can modulate aggregation. In order to allow the bioinformatic investigation of the context of polyglutamines, we have constructed a database, PolyQ (http://pxgrid.med.monash.edu.au/polyq). We have collected the sequences of all human proteins containing runs of seven or more glutamine residues and annotated their sequences with domain information. PolyQ can be interrogated such that the sequence context of polyglutamine repeats in disease and non-disease associated proteins can be investigated.
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Affiliation(s)
- Amy L Robertson
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Nursing and Health Sciences, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia
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