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Mishra R, Gerlach GJ, Sahoo B, Camacho CJ, Wetzel R. A Targetable Self-association Surface of the Huntingtin exon1 Helical Tetramer Required for Assembly of Amyloid Pre-nucleation Oligomers. J Mol Biol 2024; 436:168607. [PMID: 38734203 DOI: 10.1016/j.jmb.2024.168607] [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: 12/13/2023] [Revised: 05/03/2024] [Accepted: 05/06/2024] [Indexed: 05/13/2024]
Abstract
Polyglutamine (polyQ) sequences undergo repeat-length dependent formation of disease-associated, amyloid-like cross-β core structures with kinetics and aggregate morphologies often influenced by the flanking sequences. In Huntington's disease (HD), the httNT segment on the polyQ's N-terminal flank enhances aggregation rates by changing amyloid nucleation from a classical homogeneous mechanism to a two-step process requiring an ɑ-helix-rich oligomeric intermediate. A folded, helix-rich httNT tetrameric structure suggested to be this critical intermediate was recently reported. Here we employ single alanine replacements along the httNT sequence to assess this proposed structure and refine the mechanistic model. We find that Ala replacement of hydrophobic residues within simple httNT peptides greatly suppresses helicity, supporting the tetramer model. These same helix-disruptive replacements in the httNT segment of an exon-1 analog greatly reduce aggregation kinetics, suggesting that an ɑ-helix rich multimer - either the tetramer or a larger multimer - plays an on-pathway role in nucleation. Surprisingly, several other Ala replacements actually enhance helicity and/or amyloid aggregation. The spatial localization of these residues on the tetramer surface suggests a self-association interface responsible for formation of the octomers and higher-order multimers most likely required for polyQ amyloid nucleation. Multimer docking of the tetramer, using the protein-protein docking algorithm ClusPro, predicts this symmetric surface to be a viable tetramer dimerization interface. Intriguingly, octomer formation brings the emerging polyQ chains into closer proximity at this tetramer-tetramer interface. Further supporting the potential importance of tetramer super-assembly, computational docking with a known exon-1 aggregation inhibitor predicts ligand contacts with residues at this interface.
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Affiliation(s)
- Rakesh Mishra
- Department Structural Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
| | - Gabriella J Gerlach
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA
| | - Bankanidhi Sahoo
- Department Structural Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
| | - Carlos J Camacho
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
| | - Ronald Wetzel
- Department Structural Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
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2
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Torricella F, Tugarinov V, Clore GM. Nucleation of Huntingtin Aggregation Proceeds via Conformational Conversion of Pre-Formed, Sparsely-Populated Tetramers. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2309217. [PMID: 38476051 PMCID: PMC11199967 DOI: 10.1002/advs.202309217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/18/2024] [Indexed: 03/14/2024]
Abstract
Pathogenic huntingtin exon-1 protein (httex1), characterized by an expanded polyglutamine tract located between the N-terminal amphiphilic region and a C-terminal polyproline-rich domain, forms fibrils that accumulate in neuronal inclusion bodies, and is associated with a fatal, autosomal dominant neurodegenerative condition known as Huntington's disease. Here a complete kinetic model is described for aggregation/fibril formation of a httex1 construct with a 35-residue polyglutamine repeat, httex1Q35. Using exchange NMR spectroscopy, it is previously shown that the reversible formation of a sparsely-populated tetramer of the N-terminal amphiphilic domain of httex1Q35, comprising a D2 symmetric four-helix bundle, occurs on the microsecond time-scale and is a prerequisite for subsequent nucleation and fibril formation on a time scale that is many orders of magnitude slower (hours). Here a unified kinetic model of httex1Q35 aggregation is developed in which fast, reversible tetramerization is directly linked to slow irreversible fibril formation via conversion of pre-equilibrated tetrameric species to "active", chain elongation-capable nuclei by conformational re-arrangement with a finite, monomer-independent rate. The unified model permits global quantitative analysis of reversible tetramerization and irreversible fibril formation from a time series of 1H-15N correlation spectra recorded during the course of httex1Q35 aggregation.
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Affiliation(s)
- Francesco Torricella
- Laboratory of Chemical PhysicsNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMD20892‐0520USA
| | - Vitali Tugarinov
- Laboratory of Chemical PhysicsNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMD20892‐0520USA
| | - G. Marius Clore
- Laboratory of Chemical PhysicsNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMD20892‐0520USA
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3
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Kumar M, Tyagi N, Faruq M. The molecular mechanisms of spinocerebellar ataxias for DNA repeat expansion in disease. Emerg Top Life Sci 2023; 7:289-312. [PMID: 37668011 DOI: 10.1042/etls20230013] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/01/2023] [Accepted: 08/16/2023] [Indexed: 09/06/2023]
Abstract
Spinocerebellar ataxias (SCAs) are a heterogenous group of neurodegenerative disorders which commonly inherited in an autosomal dominant manner. They cause muscle incoordination due to degeneration of the cerebellum and other parts of nervous system. Out of all the characterized (>50) SCAs, 14 SCAs are caused due to microsatellite repeat expansion mutations. Repeat expansions can result in toxic protein gain-of-function, protein loss-of-function, and/or RNA gain-of-function effects. The location and the nature of mutation modulate the underlying disease pathophysiology resulting in varying disease manifestations. Potential toxic effects of these mutations likely affect key major cellular processes such as transcriptional regulation, mitochondrial functioning, ion channel dysfunction and synaptic transmission. Involvement of several common pathways suggests interlinked function of genes implicated in the disease pathogenesis. A better understanding of the shared and distinct molecular pathogenic mechanisms in these diseases is required to develop targeted therapeutic tools and interventions for disease management. The prime focus of this review is to elaborate on how expanded 'CAG' repeats contribute to the common modes of neurotoxicity and their possible therapeutic targets in management of such devastating disorders.
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Affiliation(s)
- Manish Kumar
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
| | - Nishu Tyagi
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
| | - Mohammed Faruq
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
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Koch L, Pollak R, Ebbinghaus S, Huber K. A Comparative Study on Cyanine Dyestuffs as Sensor Candidates for Macromolecular Crowding In Vitro and In Vivo. BIOSENSORS 2023; 13:720. [PMID: 37504118 PMCID: PMC10377163 DOI: 10.3390/bios13070720] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/30/2023] [Accepted: 07/04/2023] [Indexed: 07/29/2023]
Abstract
Pseudo isocyanine chloride (PIC) has been identified in a preceding work as a sensor suited to probe macromolecular crowding both in test tubes with solutions of synthetic crowding agents and in HeLa cells as a representative of living systems. The sensing is based on a delicate response of the self-assembly pattern of PIC towards a variation in macromolecular crowding. Based on a suitable selection of criteria established in the present study, four additional cyanine dyestuffs (TDBC, S071, S2275, and PCYN) were scrutinized for their ability to act as such a sensor, and the results were compared with the corresponding performance of PIC. UV-VIS and fluorescence spectroscopy were applied to investigate the photo-physical properties of the four candidates and, if possible, light scattering was used to characterize the self-assembly of the dyestuffs in solution. Finally, HeLa cells were exposed to solutions of the most promising candidates in order to analyze their ability to infiltrate the cells and to self-assemble therein. None of the dyestuff candidates turned out to be as similarly promising in probing crowding effects in cells as PIC turned out to be. S0271 and S2275 are at least stable enough and meet the photophysical requirements necessary to act as sensors responding to changes in macromolecular crowding.
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Affiliation(s)
- Leon Koch
- Physical Chemistry, Department of Chemistry, Paderborn University, 33098 Paderborn, Germany
| | - Roland Pollak
- Physical and Theoretical Chemistry, Faculty of Live Science, TU Braunschweig, 38106 Braunschweig, Germany
| | - Simon Ebbinghaus
- Physical and Theoretical Chemistry, Faculty of Live Science, TU Braunschweig, 38106 Braunschweig, Germany
| | - Klaus Huber
- Physical Chemistry, Department of Chemistry, Paderborn University, 33098 Paderborn, Germany
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Hart HS, Valentin MA, Peters ST, Holler SW, Wang H, Harmon AF, Holler LD. The cytoprotective role of GM1 ganglioside in Huntington disease cells. Mol Biol Rep 2022; 49:12253-12258. [PMID: 36180805 PMCID: PMC9712292 DOI: 10.1007/s11033-022-07830-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 07/29/2022] [Indexed: 02/01/2023]
Abstract
BACKGROUND Huntington disease (HD) is a neurodegenerative disease where a genetic mutation leads to excessive polyglutamine (Q) repeats in the huntingtin protein. The polyglutamine repeats create toxic plaques when the protein is cleaved, leading to neuron death. The glycolipid GM1 ganglioside (GM1) has been shown to be neuroprotective in HD models, as it prevents the cleavage of the mutant huntingtin protein by phosphorylation of serine 13 and 16. Previous studies have tested GM1 in both adult-onset and juvenile-onset HD models, but this study set out to investigate whether GM1 mediated cytoprotection is influenced by the length of polyglutamine repeats. METHOD AND RESULT This study utilized cell culture to analyze the effect of GM1 on cell viability, directly comparing the response between cells with adult-onset HD and juvenile-onset HD. HEK293 cells expressing either wild-type huntingtin (Htt) (19Q) exon 1, adult-onset HD mutant Htt exon 1 (55Q), or Juvenile HD mutant Htt exon 1 (94Q) were assessed for cell viability using the WST-1 assay. Our results suggested moderate doses of GM1 increased cell viability for all cell lines when compared to untreated cells. When comparing HEK293 55Q and 94Q cells, there was no difference in cell viability within each dose of GM1. CONCLUSION These data suggest cellular responses to GM1 are independent of polyglutamine repeats in HD cells and provide insight on GM1's application as a therapeutic agent for HD and other diseases.
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Affiliation(s)
| | - Madeline A. Valentin
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD USA
| | | | | | - Hongmin Wang
- Division of Basic Biomedical Sciences and Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, SD USA
| | - Aaron F. Harmon
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD USA
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6
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N-alpha-acetylation of Huntingtin protein increases its propensity to aggregate. J Biol Chem 2021; 297:101363. [PMID: 34732320 PMCID: PMC8640455 DOI: 10.1016/j.jbc.2021.101363] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/23/2021] [Accepted: 10/25/2021] [Indexed: 11/22/2022] Open
Abstract
Huntington’s disease (HD) is a neurodegenerative disorder caused by a poly-CAG expansion in the first exon of the HTT gene, resulting in an extended poly-glutamine tract in the N-terminal domain of the Huntingtin (Htt) protein product. Proteolytic fragments of the poly-glutamine–containing N-terminal domain form intranuclear aggregates that are correlated with HD. Post-translational modification of Htt has been shown to alter its function and aggregation properties. However, the effect of N-terminal Htt acetylation has not yet been considered. Here, we developed a bacterial system to produce unmodified or N-terminally acetylated and aggregation-inducible Htt protein. We used this system together with biochemical, biophysical, and imaging studies to confirm that the Htt N-terminus is an in vitro substrate for the NatA N-terminal acetyltransferase and show that N-terminal acetylation promotes aggregation. These studies represent the first link between N-terminal acetylation and the promotion of a neurodegenerative disease and implicates NatA-mediated Htt acetylation as a new potential therapeutic target in HD.
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Pigazzini ML, Lawrenz M, Margineanu A, Kaminski Schierle GS, Kirstein J. An Expanded Polyproline Domain Maintains Mutant Huntingtin Soluble in vivo and During Aging. Front Mol Neurosci 2021; 14:721749. [PMID: 34720872 PMCID: PMC8554126 DOI: 10.3389/fnmol.2021.721749] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/30/2021] [Indexed: 02/02/2023] Open
Abstract
Huntington's disease is a dominantly inherited neurodegenerative disorder caused by the expansion of a CAG repeat, encoding for the amino acid glutamine (Q), present in the first exon of the protein huntingtin. Over the threshold of Q39 HTT exon 1 (HTTEx1) tends to misfold and aggregate into large intracellular structures, but whether these end-stage aggregates or their on-pathway intermediates are responsible for cytotoxicity is still debated. HTTEx1 can be separated into three domains: an N-terminal 17 amino acid region, the polyglutamine (polyQ) expansion and a C-terminal proline rich domain (PRD). Alongside the expanded polyQ, these flanking domains influence the aggregation propensity of HTTEx1: with the N17 initiating and promoting aggregation, and the PRD modulating it. In this study we focus on the first 11 amino acids of the PRD, a stretch of pure prolines, which are an evolutionary recent addition to the expanding polyQ region. We hypothesize that this proline region is expanding alongside the polyQ to counteract its ability to misfold and cause toxicity, and that expanding this proline region would be overall beneficial. We generated HTTEx1 mutants lacking both flanking domains singularly, missing the first 11 prolines of the PRD, or with this stretch of prolines expanded. We then followed their aggregation landscape in vitro with a battery of biochemical assays, and in vivo in novel models of C. elegans expressing the HTTEx1 mutants pan-neuronally. Employing fluorescence lifetime imaging we could observe the aggregation propensity of all HTTEx1 mutants during aging and correlate this with toxicity via various phenotypic assays. We found that the presence of an expanded proline stretch is beneficial in maintaining HTTEx1 soluble over time, regardless of polyQ length. However, the expanded prolines were only advantageous in promoting the survival and fitness of an organism carrying a pathogenic stretch of Q48 but were extremely deleterious to the nematode expressing a physiological stretch of Q23. Our results reveal the unique importance of the prolines which have and still are evolving alongside expanding glutamines to promote the function of HTTEx1 and avoid pathology.
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Affiliation(s)
- Maria Lucia Pigazzini
- Department of Molecular Physiology and Cell Biology, Leibniz Research Institute for Molecular Pharmacology in the Forschungsverbund Berlin e.V. (FMP), Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Mandy Lawrenz
- Department of Molecular Physiology and Cell Biology, Leibniz Research Institute for Molecular Pharmacology in the Forschungsverbund Berlin e.V. (FMP), Berlin, Germany
| | - Anca Margineanu
- Advanced Light Microscopy, Max-Delbrück Centrum for Molecular Medicine (MDC), Berlin, Germany
| | - Gabriele S. Kaminski Schierle
- Molecular Neuroscience Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Janine Kirstein
- Department of Molecular Physiology and Cell Biology, Leibniz Research Institute for Molecular Pharmacology in the Forschungsverbund Berlin e.V. (FMP), Berlin, Germany
- Department of Cell Biology, University of Bremen, Bremen, Germany
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8
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Chongtham A, Isas JM, Pandey NK, Rawat A, Yoo JH, Mastro T, Kennedy MB, Langen R, Khoshnan A. Amplification of neurotoxic HTTex1 assemblies in human neurons. Neurobiol Dis 2021; 159:105517. [PMID: 34563643 DOI: 10.1016/j.nbd.2021.105517] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/24/2021] [Accepted: 09/21/2021] [Indexed: 11/25/2022] Open
Abstract
Huntington's disease (HD) is a genetically inherited neurodegenerative disorder caused by expansion of a polyglutamine (polyQ) repeat in the exon-1 of huntingtin protein (HTT). The expanded polyQ enhances the amyloidogenic propensity of HTT exon 1 (HTTex1), which forms a heterogeneous mixture of assemblies with a broad neurotoxicity spectrum. While predominantly intracellular, monomeric and aggregated mutant HTT species are also present in the cerebrospinal fluids of HD patients, however, their biological properties are not well understood. To explore the role of extracellular mutant HTT in aggregation and toxicity, we investigated the uptake and amplification of recombinant HTTex1 assemblies in cell culture models. We find that small HTTex1 fibrils preferentially enter human neurons and trigger the amplification of neurotoxic assemblies; astrocytes or epithelial cells are not permissive. The amplification of HTTex1 in neurons depletes endogenous HTT protein with non-pathogenic polyQ repeat, activates apoptotic caspase-3 pathway and induces nuclear fragmentation. Using a panel of novel monoclonal antibodies and genetic mutation, we identified epitopes within the N-terminal 17 amino acids and proline-rich domain of HTTex1 to be critical in neural uptake and amplification. Synaptosome preparations from the brain homogenates of HD mice also contain mutant HTT species, which enter neurons and behave similar to small recombinant HTTex1 fibrils. These studies suggest that amyloidogenic extracellular mutant HTTex1 assemblies may preferentially enter neurons, propagate and promote neurodegeneration.
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Affiliation(s)
| | - J Mario Isas
- Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | - Nitin K Pandey
- Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | - Anoop Rawat
- Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | - Jung Hyun Yoo
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | - Tara Mastro
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | - Mary B Kennedy
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | - Ralf Langen
- Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | - Ali Khoshnan
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA.
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9
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Marquette A, Aisenbrey C, Bechinger B. Membrane Interactions Accelerate the Self-Aggregation of Huntingtin Exon 1 Fragments in a Polyglutamine Length-Dependent Manner. Int J Mol Sci 2021; 22:ijms22136725. [PMID: 34201610 PMCID: PMC8268948 DOI: 10.3390/ijms22136725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/07/2021] [Accepted: 06/18/2021] [Indexed: 12/04/2022] Open
Abstract
The accumulation of aggregated protein is a typical hallmark of many human neurodegenerative disorders, including polyglutamine-related diseases such as chorea Huntington. Misfolding of the amyloidogenic proteins gives rise to self-assembled complexes and fibres. The huntingtin protein is characterised by a segment of consecutive glutamines which, when exceeding ~ 37 residues, results in the occurrence of the disease. Furthermore, it has also been demonstrated that the 17-residue amino-terminal domain of the protein (htt17), located upstream of this polyglutamine tract, strongly correlates with aggregate formation and pathology. Here, we demonstrate that membrane interactions strongly accelerate the oligomerisation and β-amyloid fibril formation of htt17-polyglutamine segments. By using a combination of biophysical approaches, the kinetics of fibre formation is investigated and found to be strongly dependent on the presence of lipids, the length of the polyQ expansion, and the polypeptide-to-lipid ratio. Finally, the implications for therapeutic approaches are discussed.
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Affiliation(s)
- Arnaud Marquette
- Chemistry Institute UMR7177, University of Strasbourg/CNRS, 67000 Strasbourg, France; (A.M.); (C.A.)
| | - Christopher Aisenbrey
- Chemistry Institute UMR7177, University of Strasbourg/CNRS, 67000 Strasbourg, France; (A.M.); (C.A.)
| | - Burkhard Bechinger
- Chemistry Institute UMR7177, University of Strasbourg/CNRS, 67000 Strasbourg, France; (A.M.); (C.A.)
- Insitut Universitaire de France, 75005 Paris, France
- Correspondence:
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10
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Schindler F, Praedel N, Neuendorf N, Kunz S, Schnoegl S, Mason MA, Taxy BA, Bates GP, Khoshnan A, Priller J, Grimm J, Maier M, Boeddrich A, Wanker EE. Small, Seeding-Competent Huntingtin Fibrils Are Prominent Aggregate Species in Brains of zQ175 Huntington's Disease Knock-in Mice. Front Neurosci 2021; 15:682172. [PMID: 34239412 PMCID: PMC8257939 DOI: 10.3389/fnins.2021.682172] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/31/2021] [Indexed: 12/21/2022] Open
Abstract
The deposition of mutant huntingtin (mHTT) protein aggregates in neurons of patients is a pathological hallmark of Huntington’s disease (HD). Previous investigations in cell-free and cell-based disease models showed mHTT exon-1 (mHTTex1) fragments with pathogenic polyglutamine (polyQ) tracts (>40 glutamines) to self-assemble into highly stable, β-sheet-rich protein aggregates with a fibrillar morphology. HD knock-in mouse models have not been extensively studied with regard to mHTT aggregation. They endogenously produce full-length mHTT with a pathogenic polyQ tract as well as mHTTex1 fragments. Here, we demonstrate that seeding-competent, fibrillar mHTT aggregates can be readily detected in brains of zQ175 knock-in HD mice. To do this, we applied a highly sensitive FRET-based protein amplification assay that is capable of detecting seeding-competent mHTT aggregate species down to the femtomolar range. Furthermore, we show that fibrillar structures with an average length of ∼200 nm can be enriched with aggregate-specific mouse and human antibodies from zQ175 mouse brain extracts through immunoprecipitations, confirming that such structures are formed in vivo. Together these studies indicate that small, fibrillar, seeding-competent mHTT structures are prominent aggregate species in brains of zQ175 mice.
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Affiliation(s)
- Franziska Schindler
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Nicole Praedel
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Nancy Neuendorf
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Severine Kunz
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Sigrid Schnoegl
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Michael A Mason
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UK Dementia Research Centre, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Bridget A Taxy
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UK Dementia Research Centre, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Gillian P Bates
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UK Dementia Research Centre, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Ali Khoshnan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Josef Priller
- Department of Psychiatry and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany.,Charité-Universitätsmedizin Berlin and DZNE, Berlin, Germany.,The University of Edinburgh, UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Jan Grimm
- Neurimmune AG, Schlieren, Switzerland
| | | | - Annett Boeddrich
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Erich E Wanker
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
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11
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Chongtham A, Bornemann DJ, Barbaro BA, Lukacsovich T, Agrawal N, Syed A, Worthge S, Purcell J, Burke J, Chin TM, Marsh JL. Effects of flanking sequences and cellular context on subcellular behavior and pathology of mutant HTT. Hum Mol Genet 2021; 29:674-688. [PMID: 31943010 DOI: 10.1093/hmg/ddaa001] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/06/2019] [Accepted: 01/07/2020] [Indexed: 12/11/2022] Open
Abstract
Huntington's disease (HD) is caused by an expansion of a poly glutamine (polyQ) stretch in the huntingtin protein (HTT) that is necessary to cause pathology and formation of HTT aggregates. Here we ask whether expanded polyQ is sufficient to cause pathology and aggregate formation. By addressing the sufficiency question, one can identify cellular processes and structural parameters that influence HD pathology and HTT subcellular behavior (i.e. aggregation state and subcellular location). Using Drosophila, we compare the effects of expressing mutant full-length human HTT (fl-mHTT) to the effects of mutant human HTTexon1 and to two commonly used synthetic fragments, HTT171 and shortstop (HTT118). Expanded polyQ alone is not sufficient to cause inclusion formation since full-length HTT and HTTex1 with expanded polyQ are both toxic although full-length HTT remains diffuse while HTTex1 forms inclusions. Further, inclusions are not sufficient to cause pathology since HTT171-120Q forms inclusions but is benign and co-expression of HTT171-120Q with non-aggregating pathogenic fl-mHTT recruits fl-mHTT to aggregates and rescues its pathogenicity. Additionally, the influence of sequences outside the expanded polyQ domain is revealed by finding that small modifications to the HTT118 or HTT171 fragments can dramatically alter their subcellular behavior and pathogenicity. Finally, mutant HTT subcellular behavior is strongly modified by different cell and tissue environments (e.g. fl-mHTT appears as diffuse nuclear in one tissue and diffuse cytoplasmic in another but toxic in both). These observations underscore the importance of cellular and structural context for the interpretation and comparison of experiments using different fragments and tissues to report the effects of expanded polyQ.
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Affiliation(s)
- Anjalika Chongtham
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA.,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125
| | - Douglas J Bornemann
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - Brett A Barbaro
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - Tamas Lukacsovich
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - Namita Agrawal
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - Adeela Syed
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - Shane Worthge
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - Judith Purcell
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - John Burke
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
| | - Theodore M Chin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125
| | - J Lawrence Marsh
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, 92697-2300, USA
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12
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Chen YW, Rahman SK. Fatal Attraction: The Case of Toxic Soluble Dimers of Truncated PQBP-1 Mutants in X-Linked Intellectual Disability. Int J Mol Sci 2021; 22:ijms22052240. [PMID: 33668121 PMCID: PMC7956452 DOI: 10.3390/ijms22052240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/20/2021] [Accepted: 02/20/2021] [Indexed: 11/16/2022] Open
Abstract
The frameshift mutants K192Sfs*7 and R153Sfs*41, of the polyglutamine tract-binding protein 1 (PQBP-1), are stable intrinsically disordered proteins (IDPs). They are each associated with the severe cognitive disorder known as the Renpenning syndrome, a form of X-linked intellectual disability (XLID). Relative to the monomeric wild-type protein, these mutants are dimeric, contain more folded contents, and have higher thermal stabilities. Comparisons can be drawn to the toxic oligomerisation in the “conformational diseases”, which collectively describe medical conditions involving a substantial protein structural transition in the pathogenic mechanism. At the molecular level, the end state of these diseases is often cytotoxic protein aggregation. The conformational disease proteins contain varying extents of intrinsic disorder, and the consensus pathogenesis includes an early oligomer formation. We reviewed the experimental characterisation of the toxic oligomers in representative cases. PQBP-1 mutant dimerisation was then compared to the oligomerisation of the conformational disease proteins. The PQBP-1 mutants are unique in behaving as stable soluble dimers, which do not further develop into higher oligomers or aggregates. The toxicity of the PQBP-1 mutant dimers lies in the native functions (in transcription regulation and possibly, RNA splicing) being compromised, rather than proceeding to aggregation. Other examples of stable IDP dimers were discussed and we speculated on the roles of IDP dimerisation in protein evolution.
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Affiliation(s)
- Yu Wai Chen
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hunghom 999077, Hong Kong
- State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hunghom 999077, Hong Kong
- Correspondence:
| | - Shah Kamranur Rahman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK;
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13
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Wetzel R. Exploding the Repeat Length Paradigm while Exploring Amyloid Toxicity in Huntington's Disease. Acc Chem Res 2020; 53:2347-2357. [PMID: 32975927 DOI: 10.1021/acs.accounts.0c00450] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Huntington's disease (HD) is a progressive, familial neurodegenerative disease triggered by the expansion of a polyglutamine (polyQ) track in the protein huntingtin (htt). PolyQ sequences up to Q36 in htt are not known to be toxic, while polyQ lengths above Q36 almost invariably lead to increased disease risk and decreased ages of onset. The large number of physical states (monomers, dimers, tetramers, non-β oligomers, nanofibrils, and clustered amyloid fibrils) on the self-association landscape, with their overlapping kinetics of formation, have greatly complicated identification of the molecular species responsible for HD toxicity, drawing attention to the need for innovative approaches.After reports of HD-associated intraneuronal htt inclusions in 1997, we elucidated aggregation mechanisms of both simple polyQ sequences and the more complex polyQ-containing "exon1" fragment of htt (htt-ex1). Grounded in this work, the more recent results described here were made possible by breakthroughs in the molecular design of diagnostic polyQ derivatives and in fluorescence applications for characterizing amyloid assembly intermediates. Thus, insertion of β-turn-promoting mutations into relatively short, disordered polyQ sequences created "pro-β-hairpin" polyQs (βHPs) that exhibit amyloid formation rates comparable to the enhanced rates seen with expanded polyQ peptides. Introduction of "β-breaker" mutations into these βHP polyQ sequences created molecules that are blocked from aggregating into amyloid and also can inhibit amyloid formation by other polyQ proteins. These mutational effects were then successfully transferred into more complex htt-ex1 sequence backgrounds. Insights into the aggregation properties of htt-ex1 derivatives-as well as into the nucleation process itself-were obtained using fluorescence correlation spectroscopy (FCS) and a novel thioflavin-T (ThT) protocol that allows quantitation of htt-ex1 assembly intermediates.Using these tools, we quantified physical states of htt-ex1 at different growth times in mammalian PC12 cells engineered for inducible expression of both normal and expanded polyQ repeat length versions of htt-ex1. For expanded polyQ versions, we found tetramers, oligomers, and fibrils (but no monomers) all populated in these cells at a time when the first indication of toxicity (nuclear DNA damage) was observed. These experiments provided a strong hint that monomeric forms of htt-ex1 are not involved in toxicity, but we were otherwise unable to implicate a specific toxic self-assembled state because of the overlapping kinetics of formation. To gain a more intimate focus and control over the timelines of htt-ex1 self-assembly and the resulting toxic response, we engineered various htt-ex1-βHP molecules-with and without added β-breaker mutations-that could be expressed in rat neuronal and Drosophila models of HD. In both models, novel htt-ex1-βHP analogues exhibiting strong aggregation in spite of their very short polyQ repeat lengths proved to be toxic, dramatically breaking the "repeat length paradigm" and strongly suggesting that the toxic species must be some kind of aggregate. In both models, β-breaker analogues of htt-ex1-βHP that are slow to make amyloid-instead favoring accumulation of non-β oligomers-were nontoxic. In contrast, htt-ex1-βHP analogues that rapidly progress to amyloid states were toxic, suggesting that an aggregate possessing the fundamental amyloid folding motif is very likely the major toxic species in HD.
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Affiliation(s)
- Ronald Wetzel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Biomedical Sciences Tower 3, 3501 Fifth Avenue, Pittsburgh, Pennsylvania 15260, United States
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14
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Morató A, Elena-Real CA, Popovic M, Fournet A, Zhang K, Allemand F, Sibille N, Urbanek A, Bernadó P. Robust Cell-Free Expression of Sub-Pathological and Pathological Huntingtin Exon-1 for NMR Studies. General Approaches for the Isotopic Labeling of Low-Complexity Proteins. Biomolecules 2020; 10:E1458. [PMID: 33086646 PMCID: PMC7603387 DOI: 10.3390/biom10101458] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/07/2020] [Accepted: 10/16/2020] [Indexed: 12/23/2022] Open
Abstract
The high-resolution structural study of huntingtin exon-1 (HttEx1) has long been hampered by its intrinsic properties. In addition to being prone to aggregate, HttEx1 contains low-complexity regions (LCRs) and is intrinsically disordered, ruling out several standard structural biology approaches. Here, we use a cell-free (CF) protein expression system to robustly and rapidly synthesize (sub-) pathological HttEx1. The open nature of the CF reaction allows the application of different isotopic labeling schemes, making HttEx1 amenable for nuclear magnetic resonance studies. While uniform and selective labeling facilitate the sequential assignment of HttEx1, combining CF expression with nonsense suppression allows the site-specific incorporation of a single labeled residue, making possible the detailed investigation of the LCRs. To optimize CF suppression yields, we analyze the expression and suppression kinetics, revealing that high concentrations of loaded suppressor tRNA have a negative impact on the final reaction yield. The optimized CF protein expression and suppression system is very versatile and well suited to produce challenging proteins with LCRs in order to enable the characterization of their structure and dynamics.
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Affiliation(s)
| | | | | | | | | | | | | | - Annika Urbanek
- Centre de Biochimie Structurale (CBS), INSERM, CNRS and Université de Montpellier. 29 rue de Navacelles, 34090 Montpellier, France; (A.M.); (C.A.E.-R.); (M.P.); (A.F.); (K.Z.); (F.A.); (N.S.)
| | - Pau Bernadó
- Centre de Biochimie Structurale (CBS), INSERM, CNRS and Université de Montpellier. 29 rue de Navacelles, 34090 Montpellier, France; (A.M.); (C.A.E.-R.); (M.P.); (A.F.); (K.Z.); (F.A.); (N.S.)
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15
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Palomino‐Hernandez O, Margreiter MA, Rossetti G. Challenges in RNA Regulation in Huntington's Disease: Insights from Computational Studies. Isr J Chem 2020. [DOI: 10.1002/ijch.202000021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Oscar Palomino‐Hernandez
- Computational Biomedicine, Institute of Neuroscience and Medicine (INM-9)/Instute for advanced simulations (IAS-5)Forschungszentrum Juelich 52425 Jülich Germany
- Faculty 1RWTH Aachen 52425 Aachen Germany
- Computation-based Science and Technology Research CenterThe Cyprus Institute Nicosia 2121 Cyprus
- Institute of Life ScienceThe Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Michael A. Margreiter
- Computational Biomedicine, Institute of Neuroscience and Medicine (INM-9)/Instute for advanced simulations (IAS-5)Forschungszentrum Juelich 52425 Jülich Germany
- Faculty 1RWTH Aachen 52425 Aachen Germany
| | - Giulia Rossetti
- Computational Biomedicine, Institute of Neuroscience and Medicine (INM-9)/Instute for advanced simulations (IAS-5)Forschungszentrum Juelich 52425 Jülich Germany
- Jülich Supercomputing Centre (JSC)Forschungszentrum Jülich 52425 Jülich Germany
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation University Hospital AachenRWTH Aachen University Pauwelsstraße 30 52074 Aachen Germany
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16
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Maxan A, Sciacca G, Alpaugh M, Tao Z, Breger L, Dehay B, Ling Z, Chuan Q, Cisbani G, Masnata M, Salem S, Lacroix S, Oueslati A, Bezard E, Cicchetti F. Use of adeno-associated virus-mediated delivery of mutant huntingtin to study the spreading capacity of the protein in mice and non-human primates. Neurobiol Dis 2020; 141:104951. [PMID: 32439599 DOI: 10.1016/j.nbd.2020.104951] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/20/2020] [Accepted: 05/16/2020] [Indexed: 01/27/2023] Open
Abstract
In order to model various aspects of Huntington's disease (HD) pathology, in particular protein spread, we administered adeno-associated virus (AAV) expressing green fluorescent protein (GFP) or GFP coupled to HTT-Exon1 (19Q or 103Q) to the central nervous system of adult wild-type (WT) mice and non-human primates. All animals underwent behavioral testing and post-mortem analyses to determine the long-term consequences of AAV injection. Both mice and non-human primates demonstrated behavioral changes at 2-3 weeks post-surgery. In mice, these changes were absent after 3 months while in non-human primates, they persisted in the majority of tested animals. Post-mortem analysis revealed that spreading of the aggregates was limited, although the virus did spread between synaptically-connected brain regions. Despite circumscribed spreading, the presence of mHTT generated changes in endogenous huntingtin (HTT) levels in both models. Together, these results suggest that viral expression of mHTTExon1 can induce spreading and seeding of HTT in both mice and non-human primates.
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Affiliation(s)
- Alexander Maxan
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Giacomo Sciacca
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Melanie Alpaugh
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Zhu Tao
- Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, China
| | - Ludivine Breger
- Université de Bordeaux, Institut des maladies neurodégénératives, UMR 5293, CNRS UMR 5293, Bordeaux, France; Centre National de la Recherche Scientifique, Institut des maladies neurodégénératives, UMR 5293, 33076 Bordeaux, France
| | - Benjamin Dehay
- Université de Bordeaux, Institut des maladies neurodégénératives, UMR 5293, CNRS UMR 5293, Bordeaux, France; Centre National de la Recherche Scientifique, Institut des maladies neurodégénératives, UMR 5293, 33076 Bordeaux, France
| | - Zhang Ling
- Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, China
| | - Qin Chuan
- Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, China.
| | - Giulia Cisbani
- University of Toronto, Department of Nutritional Sciences, Toronto, ON M5S 1A8, Canada
| | - Maria Masnata
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Shireen Salem
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Steve Lacroix
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada; Département de Médicine Moléculaire, Université Laval, Québec, QC G1K 0A6, Canada
| | - Abid Oueslati
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada; Département de Médicine Moléculaire, Université Laval, Québec, QC G1K 0A6, Canada
| | - Erwan Bezard
- Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, China; Université de Bordeaux, Institut des maladies neurodégénératives, UMR 5293, CNRS UMR 5293, Bordeaux, France; Centre National de la Recherche Scientifique, Institut des maladies neurodégénératives, UMR 5293, 33076 Bordeaux, France
| | - Francesca Cicchetti
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada; Département de Psychiatrie & Neurosciences, Université Laval, Québec, QC G1K 0A6, Canada.
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17
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Bartl S, Oueslati A, Southwell AL, Siddu A, Parth M, David LS, Maxan A, Salhat N, Burkert M, Mairhofer A, Friedrich T, Pankevych H, Balazs K, Staffler G, Hayden MR, Cicchetti F, Smrzka OW. Inhibiting cellular uptake of mutant huntingtin using a monoclonal antibody: Implications for the treatment of Huntington's disease. Neurobiol Dis 2020; 141:104943. [PMID: 32407769 DOI: 10.1016/j.nbd.2020.104943] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/08/2020] [Accepted: 05/06/2020] [Indexed: 12/24/2022] Open
Abstract
Huntington's disease (HD) is caused by a highly polymorphic CAG trinucleotide expansion in the gene encoding for the huntingtin protein (HTT). The resulting mutant huntingtin protein (mutHTT) is ubiquitously expressed but also exhibits the ability to propagate from cell-to-cell to disseminate pathology; a property which may serve as a new therapeutic focus. Accordingly, we set out to develop a monoclonal antibody (mAB) targeting a particularly exposed region close to the aa586 caspase-6 cleavage site of the HTT protein. This monoclonal antibody, designated C6-17, effectively binds mutHTT and is able to deplete the protein from cell culture supernatants. Using cell-based assays, we demonstrate that extracellular secretion of mutHTT into cell culture media and its subsequent uptake in recipient HeLa cells can be almost entirely blocked by mAB C6-17. Immunohistochemical stainings of post-mortem HD brain tissue confirmed the specificity of mAB C6-17 to human mutHTT aggregates. These findings demonstrate that mAB C6-17 not only successfully engages with its target, mutHTT, but also inhibits cell uptake suggesting that this antibody could interfere with the pathological processes of mutHTT spreading in vivo.
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Affiliation(s)
| | - Abid Oueslati
- Université Laval/Centre de recherche du CHU, Québec, Canada
| | | | - Alberto Siddu
- Université Laval/Centre de recherche du CHU, Québec, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | | - Oskar W Smrzka
- AFFiRiS AG, Vienna, Austria; Ablevia biotech GmbH, Vienna, Austria
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18
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Ghosh R, Wood-Kaczmar A, Dobson L, Smith EJ, Sirinathsinghji EC, Kriston-Vizi J, Hargreaves IP, Heaton R, Herrmann F, Abramov AY, Lam AJ, Heales SJ, Ketteler R, Bates GP, Andre R, Tabrizi SJ. Expression of mutant exon 1 huntingtin fragments in human neural stem cells and neurons causes inclusion formation and mitochondrial dysfunction. FASEB J 2020; 34:8139-8154. [PMID: 32329133 PMCID: PMC8432155 DOI: 10.1096/fj.201902277rr] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 03/27/2020] [Accepted: 04/02/2020] [Indexed: 11/11/2022]
Abstract
Robust cellular models are key in determining pathological mechanisms that lead to neurotoxicity in Huntington's disease (HD) and for high throughput pre‐clinical screening of potential therapeutic compounds. Such models exist but mostly comprise non‐human or non‐neuronal cells that may not recapitulate the correct biochemical milieu involved in pathology. We have developed a new human neuronal cell model of HD, using neural stem cells (ReNcell VM NSCs) stably transduced to express exon 1 huntingtin (HTT) fragments with variable length polyglutamine (polyQ) tracts. Using a system with matched expression levels of exon 1 HTT fragments, we investigated the effect of increasing polyQ repeat length on HTT inclusion formation, location, neuronal survival, and mitochondrial function with a view to creating an in vitro screening platform for therapeutic screening. We found that expression of exon 1 HTT fragments with longer polyQ tracts led to the formation of intra‐nuclear inclusions in a polyQ length‐dependent manner during neurogenesis. There was no overt effect on neuronal viability, but defects of mitochondrial function were found in the pathogenic lines. Thus, we have a human neuronal cell model of HD that may recapitulate some of the earliest stages of HD pathogenesis, namely inclusion formation and mitochondrial dysfunction.
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Affiliation(s)
- Rhia Ghosh
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Alison Wood-Kaczmar
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Lucianne Dobson
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Edward J Smith
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Eva C Sirinathsinghji
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Janos Kriston-Vizi
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | | | - Robert Heaton
- School of Pharmacy, Liverpool John Moores University, Liverpool, UK
| | | | - Andrey Y Abramov
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Amanda J Lam
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - Simon J Heales
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - Robin Ketteler
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Gillian P Bates
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Ralph Andre
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Sarah J Tabrizi
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
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19
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Sedighi F, Adegbuyiro A, Legleiter J. SUMOylation Prevents Huntingtin Fibrillization and Localization onto Lipid Membranes. ACS Chem Neurosci 2020; 11:328-343. [PMID: 31880908 DOI: 10.1021/acschemneuro.9b00509] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Huntington's disease (HD), a genetic neurodegenerative disease, is caused by an expanded polyglutamine (polyQ) domain in the first exon of the huntingtin protein (htt). PolyQ expansion destabilizes protein structure, resulting in aggregation into a variety of oligomers, protofibrils, and fibrils. Beyond the polyQ domain, adjacent protein sequences influence the aggregation process. Specifically, the first 17 N-terminal amino acids (Nt17) directly preceding the polyQ domain promote the formation of α-helix-rich oligomers that represent intermediate species associated with fibrillization. Due to its propensity to form an amphipathic α-helix, Nt17 also facilitates lipid binding. Three lysine residues (K6, K9, and K15) within Nt17 can be SUMOylated, which modifies htt's accumulation and toxicity within cells in a variety of HD models. The impact of SUMOylation on htt aggregation and direct interaction with lipid membranes was investigated. SUMOylation of htt-exon1 inhibited fibril formation while promoting larger, amorphous aggregate species. These amorphous aggregates were SDS soluble but nonetheless exhibited levels of β-sheet structure similar to that of htt-exon1 fibrils. In addition, SUMOylation prevented htt binding, aggregation, and accumulation on model lipid bilayers comprised of total brain lipid extract. Collectively, these observations demonstrate that SUMOylation promotes a distinct htt aggregation pathway that may affect htt toxicity.
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Affiliation(s)
- Faezeh Sedighi
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States
| | - Adewale Adegbuyiro
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States
- Rockefeller Neurosciences Institutes, West Virginia University, 1 Medical Center Drive, P.O. Box 9303, Morgantown, West Virginia 26505, United States
- Department of Neuroscience, West Virginia University, 1 Medical Center Drive, P.O. Box 9303, Morgantown, West Virginia 26505, United States
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20
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Arndt JR, Chaibva M, Beasley M, Karanji AK, Kondalaji SG, Khakinejad M, Sarver O, Legleiter J, Valentine SJ. Nucleation Inhibition of Huntingtin Protein (htt) by Polyproline PPII Helices: A Potential Interaction with the N-Terminal α-Helical Region of Htt. Biochemistry 2020; 59:436-449. [PMID: 31814404 PMCID: PMC7344267 DOI: 10.1021/acs.biochem.9b00689] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Huntington's disease is a genetic neurodegenerative disorder characterized by the formation of amyloid fibrils of the huntingtin protein (htt). The 17-residue N-terminal region of htt (Nt17) has been implicated in the formation of early phase oligomeric species, which may be neurotoxic. Because tertiary interactions with a downstream (C-terminal) polyproline (polyP) region of htt may disrupt the formation of oligomers, which are precursors to fibrillar species, the effect of co-incubation of a region of htt with a 10-residue polyP peptide on oligomerization and fibrillization has been examined by atomic force microscopy. From multiple, time-course experiments, morphological changes in oligomeric species are observed for the protein/peptide mixture and compared with the protein alone. Additionally, an overall decrease in fibril formation is observed for the heterogeneous mixture. To consider potential sites of interaction between the Nt17 region and polyP, mixtures containing Nt17 and polyP peptides have been examined by ion mobility spectrometry and gas-phase hydrogen-deuterium exchange coupled with mass spectrometry. These data combined with molecular dynamics simulations suggest that the C-terminal region of Nt17 may be a primary point of contact. One interpretation of the results is that polyP may possibly regulate Nt17 by inducing a random coil region in the C-terminal portion of Nt17, thus decreasing the propensity to form the reactive amphipathic α-helix. A separate interpretation is that the residues important for helix-helix interactions are blocked by polyP association.
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Affiliation(s)
- James R Arndt
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Maxmore Chaibva
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Maryssa Beasley
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Ahmad Kiani Karanji
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Samaneh Ghassabi Kondalaji
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Mahdiar Khakinejad
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Olivia Sarver
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Justin Legleiter
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
- WV Nano Safe Iniative, West Virginia University, Morgantown, West Virginia 26506, United States
- The Center for Neuroscience, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Stephen J Valentine
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
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21
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Ko J, Isas JM, Sabbaugh A, Yoo JH, Pandey NK, Chongtham A, Ladinsky M, Wu WL, Rohweder H, Weiss A, Macdonald D, Munoz-Sanjuan I, Langen R, Patterson PH, Khoshnan A. Identification of distinct conformations associated with monomers and fibril assemblies of mutant huntingtin. Hum Mol Genet 2019; 27:2330-2343. [PMID: 29912367 DOI: 10.1093/hmg/ddy141] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 04/12/2018] [Accepted: 04/16/2018] [Indexed: 11/14/2022] Open
Abstract
The N-terminal fragments of mutant huntingtin (mHTT) misfold and assemble into oligomers, which ultimately bundle into insoluble fibrils. Conformations unique to various assemblies of mHTT remain unknown. Knowledge on the half-life of various multimeric structures of mHTT is also scarce. Using a panel of four new antibodies named PHP1-4, we have identified new conformations in monomers and assembled structures of mHTT. PHP1 and PHP2 bind to epitopes within the proline-rich domain (PRD), whereas PHP3 and PHP4 interact with motifs formed at the junction of polyglutamine (polyQ) and polyproline (polyP) repeats of HTT. The PHP1- and PHP2-reactive epitopes are exposed in fibrils of mHTT exon1 (mHTTx1) generated from recombinant proteins and mHTT assemblies, which progressively accumulate in the nuclei, cell bodies and neuropils in the brains of HD mouse models. Notably, electron microscopic examination of brain sections of HD mice revealed that PHP1- and PHP2-reactive mHTT assemblies are present in myelin sheath and in vesicle-like structures. Moreover, PHP1 and PHP2 antibodies block seeding and subsequent fibril assembly of mHTTx1 in vitro and in a cell culture model of HD. PHP3 and PHP4 bind to epitopes in full-length and N-terminal fragments of monomeric mHTT and binding diminishes as the mHTTx1 assembles into fibrils. Interestingly, PHP3 and PHP4 also prevent the aggregation of mHTTx1 in vitro highlighting a regulatory function for the polyQ-polyP motifs. These newly detected conformations may affect fibril assembly, stability and intercellular transport of mHTT.
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Affiliation(s)
- Jan Ko
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | - J Mario Isas
- Zilka Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | - Adam Sabbaugh
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | - Jung Hyun Yoo
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | - Nitin K Pandey
- Zilka Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | | | - Mark Ladinsky
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | - Wei-Li Wu
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
| | | | - Andreas Weiss
- Evotec, Manfred Eigen Campus, Hamburg 22419, Germany
| | | | | | - Ralf Langen
- Zilka Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | | | - Ali Khoshnan
- Biology and Bioengineering, Caltech, Pasadena, CA 91125, USA
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22
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Wanker EE, Ast A, Schindler F, Trepte P, Schnoegl S. The pathobiology of perturbed mutant huntingtin protein-protein interactions in Huntington's disease. J Neurochem 2019; 151:507-519. [PMID: 31418858 DOI: 10.1111/jnc.14853] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/08/2019] [Accepted: 08/02/2019] [Indexed: 12/24/2022]
Abstract
Mutations are at the root of many human diseases. Still, we largely do not exactly understand how they trigger pathogenesis. One, more recent, hypothesis has been that they comprehensively perturb protein-protein interaction (PPI) networks and significantly alter key biological processes. Under this premise, many rare genetic disorders with Mendelian inheritance, like Huntington's disease and several spinocerebellar ataxias, are likely to be caused by complex genotype-phenotype relationships involving abnormal PPIs. These altered PPI networks and their effects on cellular pathways are poorly understood at the molecular level. In this review, we focus on PPIs that are perturbed by the expanded pathogenic polyglutamine tract in huntingtin (HTT), the protein which, in its mutated form, leads to the autosomal dominant, neurodegenerative Huntington's disease. One aspect of perturbed mutant HTT interactions is the formation of abnormal protein species such as fibrils or large neuronal inclusions as a result of homotypic and heterotypic aberrant molecular interactions. This review focuses on abnormal PPIs that are associated with the assembly of mutant HTT aggregates in cells and their potential relevance in disease. Furthermore, the mechanisms and pathobiological processes that may contribute to phenotype development, neuronal dysfunction and toxicity in Huntington's disease brains are also discussed. This article is part of the Special Issue "Proteomics".
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Affiliation(s)
- Erich E Wanker
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Anne Ast
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Franziska Schindler
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Philipp Trepte
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Sigrid Schnoegl
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin, Germany
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23
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Anand BG, Prajapati KP, Dubey K, Ahamad N, Shekhawat DS, Rath PC, Joseph GK, Kar K. Self-Assembly of Artificial Sweetener Aspartame Yields Amyloid-like Cytotoxic Nanostructures. ACS NANO 2019; 13:6033-6049. [PMID: 31021591 DOI: 10.1021/acsnano.9b02284] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recent reports have revealed the intrinsic propensity of single aromatic metabolites to undergo self-assembly and form nanostructures of amyloid nature. Hence, identifying whether aspartame, a universally consumed artificial sweetener, is inherently aggregation prone becomes an important area of investigation. Although the reports on aspartame-linked side effects describe a multitude of metabolic disorders, the mechanistic understanding of such destructive effects is largely mysterious. Since aromaticity, an aggregation-promoting factor, is intrinsic to aspartame's chemistry, it is important to know whether aspartame can undergo self-association and if such a property can predispose any cytotoxicity to biological systems. Our study finds that aspartame molecules, under mimicked physiological conditions, undergo a spontaneous self-assembly process yielding regular β-sheet-like cytotoxic nanofibrils of amyloid nature. The resultant aspartame fibrils were found to trigger amyloid cross-seeding and become a toxic aggregation trap for globular proteins, Aβ peptides, and aromatic metabolites that convert native structures to β-sheet-like fibrils. Aspartame fibrils were also found to induce hemolysis, causing DNA damage resulting in both apoptosis and necrosis-mediated cell death. Specific spatial arrangement between aspartame molecules is predicted to form a regular amyloid-like architecture with a sticky exterior that is capable of promoting viable H-bonds, electrostatic interactions, and hydrophobic contacts with biomolecules, leading to the onset of protein aggregation and cell death. Results reveal that the aspartame molecule is inherently amyloidogenic, and the self-assembly of aspartame becomes a toxic trap for proteins and cells, exposing the bitter side of such a ubiquitously used artificial sweetener.
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Affiliation(s)
- Bibin Gnanadhason Anand
- Department of Bioscience and Bioengineering , Indian Institute of Technology Jodhpur , Jodhpur 342037 , India
| | | | - Kriti Dubey
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
| | - Naseem Ahamad
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
| | - Dolat Singh Shekhawat
- Department of Bioscience and Bioengineering , Indian Institute of Technology Jodhpur , Jodhpur 342037 , India
| | - Pramod Chandra Rath
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
| | - George Kodimattam Joseph
- Department of Bioscience and Bioengineering , Indian Institute of Technology Jodhpur , Jodhpur 342037 , India
| | - Karunakar Kar
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
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24
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Abstract
The spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of autosomal dominantly inherited progressive disorders, the clinical hallmark of which is loss of balance and coordination accompanied by slurred speech; onset is most often in adult life. Genetically, SCAs are grouped as repeat expansion SCAs, such as SCA3/Machado-Joseph disease (MJD), and rare SCAs that are caused by non-repeat mutations, such as SCA5. Most SCA mutations cause prominent damage to cerebellar Purkinje neurons with consecutive cerebellar atrophy, although Purkinje neurons are only mildly affected in some SCAs. Furthermore, other parts of the nervous system, such as the spinal cord, basal ganglia and pontine nuclei in the brainstem, can be involved. As there is currently no treatment to slow or halt SCAs (many SCAs lead to premature death), the clinical care of patients with SCA focuses on managing the symptoms through physiotherapy, occupational therapy and speech therapy. Intense research has greatly expanded our understanding of the pathobiology of many SCAs, revealing that they occur via interrelated mechanisms (including proteotoxicity, RNA toxicity and ion channel dysfunction), and has led to the identification of new targets for treatment development. However, the development of effective therapies is hampered by the heterogeneity of the SCAs; specific therapeutic approaches may be required for each disease.
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25
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Hansen CV, Schroll HJ, Wüstner D. A discontinuous Galerkin model for fluorescence loss in photobleaching of intracellular polyglutamine protein aggregates. BMC BIOPHYSICS 2018; 11:7. [PMID: 30519460 PMCID: PMC6264036 DOI: 10.1186/s13628-018-0046-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 10/30/2018] [Indexed: 12/03/2022]
Abstract
Background Intracellular phase separation and aggregation of proteins with extended poly-glutamine (polyQ) stretches are hallmarks of various age-associated neurodegenerative diseases. Progress in our understanding of such processes heavily relies on quantitative fluorescence imaging of suitably tagged proteins. Fluorescence loss in photobleaching (FLIP) is particularly well-suited to study the dynamics of protein aggregation in cellular models of Chorea Huntington and other polyQ diseases, as FLIP gives access to the full spatio-temporal profile of intensity changes in the cell geometry. In contrast to other methods, also dim aggregates become visible during time evolution of fluorescence loss in cellular compartments. However, methods for computational analysis of FLIP data are sparse, and transport models for estimation of transport and diffusion parameters from experimental FLIP sequences are missing. Results In this paper, we present a computational method for analysis of FLIP imaging experiments of intracellular polyglutamine protein aggregates also called inclusion bodies (IBs). By this method, we can determine the diffusion constant and nuclear membrane transport coefficients of polyQ proteins as well as the exchange rates between aggregates and the cytoplasm. Our method is based on a reaction-diffusion multi-compartment model defined on a mesh obtained by segmentation of the cell images from the FLIP sequence. The discontinuous Galerkin (DG) method is used for numerical implementation of our model in FEniCS, which greatly reduces the computing time. The method is applied to representative experimental FLIP sequences, and consistent estimates of all transport parameters are obtained. Conclusions By directly estimating the transport parameters from live-cell image sequences using our new computational FLIP approach surprisingly fast exchange dynamics of mutant Huntingtin between cytoplasm and dim IBs could be revealed. This is likely relevant also for other polyQ diseases. Thus, our method allows for quantifying protein dynamics at different stages of the protein aggregation process in cellular models of neurodegeneration. Electronic supplementary material The online version of this article (10.1186/s13628-018-0046-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Christian V Hansen
- 1Department of Mathematics and Computer Science, University of Southern Denmark, Campusvej 55, Odense M, 5230 Denmark
| | - Hans J Schroll
- 1Department of Mathematics and Computer Science, University of Southern Denmark, Campusvej 55, Odense M, 5230 Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, Campusvej 55, Odense M, 5230 Denmark
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26
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Morozova KN, Suldina LA, Malankhanova TB, Grigor’eva EV, Zakian SM, Kiseleva E, Malakhova AA. Introducing an expanded CAG tract into the huntingtin gene causes a wide spectrum of ultrastructural defects in cultured human cells. PLoS One 2018; 13:e0204735. [PMID: 30332437 PMCID: PMC6192588 DOI: 10.1371/journal.pone.0204735] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 09/13/2018] [Indexed: 11/18/2022] Open
Abstract
Modeling of neurodegenerative diseases in vitro holds great promise for biomedical research. Human cell lines harboring a mutations in disease-causing genes are thought to recapitulate early stages of the development an inherited disease. Modern genome-editing tools allow researchers to create isogenic cell clones with an identical genetic background providing an adequate "healthy" control for biomedical and pharmacological experiments. Here, we generated isogenic mutant cell clones with 150 CAG repeats in the first exon of the huntingtin (HTT) gene using the CRISPR/Cas9 system and performed ultrastructural and morphometric analyses of the internal organization of the mutant cells. Electron microscopy showed that deletion of three CAG triplets or an HTT gene knockout had no significant influence on the cell structure. The insertion of 150 CAG repeats led to substantial changes in quantitative and morphological parameters of mitochondria and increased the association of mitochondria with the smooth and rough endoplasmic reticulum while causing accumulation of small autolysosomes in the cytoplasm. Our data indicate for the first time that expansion of the CAG repeat tract in HTT introduced via the CRISPR/Cas9 technology into a human cell line initiates numerous ultrastructural defects that are typical for Huntington's disease.
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Affiliation(s)
- Ksenia N. Morozova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
| | - Lyubov A. Suldina
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - Tuyana B. Malankhanova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
- E.Meshalkin National Medical Research Center of the Ministry of Health of the Russian Federation, Novosibirsk, Russia
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - Elena V. Grigor’eva
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
- E.Meshalkin National Medical Research Center of the Ministry of Health of the Russian Federation, Novosibirsk, Russia
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - Suren M. Zakian
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
- E.Meshalkin National Medical Research Center of the Ministry of Health of the Russian Federation, Novosibirsk, Russia
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - Elena Kiseleva
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - Anastasia A. Malakhova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
- E.Meshalkin National Medical Research Center of the Ministry of Health of the Russian Federation, Novosibirsk, Russia
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
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27
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Drombosky KW, Rode S, Kodali R, Jacob TC, Palladino MJ, Wetzel R. Mutational analysis implicates the amyloid fibril as the toxic entity in Huntington's disease. Neurobiol Dis 2018; 120:126-138. [PMID: 30171891 DOI: 10.1016/j.nbd.2018.08.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 08/22/2018] [Accepted: 08/28/2018] [Indexed: 10/28/2022] Open
Abstract
In Huntington disease (HD), an expanded polyglutamine (polyQ > 37) sequence within huntingtin (htt) exon1 leads to enhanced disease risk. It has proved difficult, however, to determine whether the toxic form generated by polyQ expansion is a misfolded or avid-binding monomer, an α-helix-rich oligomer, or a β-sheet-rich amyloid fibril. Here we describe an engineered htt exon1 analog featuring a short polyQ sequence that nonetheless quickly forms amyloid fibrils and causes HD-like toxicity in rat neurons and Drosophila. Additional modifications within the polyQ segment produce htt exon1 analogs that populate only spherical oligomers and are non-toxic in cells and flies. Furthermore, in mixture with expanded-polyQ htt exon1, the latter analogs in vitro suppress amyloid formation and promote oligomer formation, and in vivo rescue neurons and flies expressing mhtt exon1 from dysfunction and death. Thus, in our experiments, while htt exon1 toxicity tracks with aggregation propensity, it does so in spite of the toxic construct's possessing polyQ tracts well below those normally considered to be disease-associated. That is, aggregation propensity proves to be a more accurate surrogate for toxicity than is polyQ repeat length itself, strongly supporting a major toxic role for htt exon1 aggregation in HD. In addition, the results suggest that the aggregates that are most toxic in these model systems are amyloid-related. These engineered analogs are novel tools for mapping properties of polyQ self-assembly intermediates and products that should similarly be useful in the analysis of other expanded polyQ diseases. Small molecules with similar amyloid inhibitory properties might be developed into effective therapeutic agents.
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Affiliation(s)
- Kenneth W Drombosky
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Graduate Program in Molecular Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sascha Rode
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ravi Kodali
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tija C Jacob
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Michael J Palladino
- Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ronald Wetzel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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28
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Sethi R, Tripathi N, Pallapati AR, Gaikar A, Bharatam PV, Roy I. Does N-terminal huntingtin function as a 'holdase' for inhibiting cellular protein aggregation? FEBS J 2018; 285:1791-1811. [PMID: 29630769 DOI: 10.1111/febs.14457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 03/14/2018] [Accepted: 03/29/2018] [Indexed: 11/28/2022]
Abstract
Proteolytic cleavage of huntingtin gives rise to N-terminal fragments. While the role of truncated mutant huntingtin is described in Huntington's disease (HD) pathogenesis, the function of N-terminal wild-type protein is less studied. The yeast model of HD is generated by the presence of FLAG tag and absence of polyproline tract as flanking sequences of the elongated polyglutamine stretch. We show that the same sequence derived from wild-type huntingtin exon1 is able to inhibit the aggregation of proteins in vitro and in yeast cells. It is able to stabilize client proteins as varied as luciferase, α-synuclein, and p53 in a soluble but non-native state. This is somewhat similar to the 'holdase' function of small heat shock proteins and 'nonchaperone proteins' which are able to stabilize partially unfolded client proteins in a nonspecific manner, slowing down their aggregation. Mutagenesis studies show this property to be localized at the N17 domain preceding the polyglutamine tract. Distortion of this ordered segment, either by deletion of this segment or mutation of a single residue (L4A), leads to decreased stability and increased aggregation of client proteins. It is interesting to note that the helical conformation of the N17 domain is also essential for aggregation of the N-terminal mutant protein. Our results provide evidence for a novel function for the amphipathic helix derived from exon1 of wild-type huntingtin.
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Affiliation(s)
- Ratnika Sethi
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Punjab, India
| | - Neha Tripathi
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Punjab, India
| | - Anusha R Pallapati
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Punjab, India
| | - Abhishek Gaikar
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Punjab, India
| | - Prasad V Bharatam
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Punjab, India.,Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Punjab, India
| | - Ipsita Roy
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Punjab, India
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29
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Wagner AS, Politi AZ, Ast A, Bravo-Rodriguez K, Baum K, Buntru A, Strempel NU, Brusendorf L, Hänig C, Boeddrich A, Plassmann S, Klockmeier K, Ramirez-Anguita JM, Sanchez-Garcia E, Wolf J, Wanker EE. Self-assembly of Mutant Huntingtin Exon-1 Fragments into Large Complex Fibrillar Structures Involves Nucleated Branching. J Mol Biol 2018; 430:1725-1744. [PMID: 29601786 DOI: 10.1016/j.jmb.2018.03.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 03/14/2018] [Accepted: 03/19/2018] [Indexed: 11/18/2022]
Abstract
Huntingtin (HTT) fragments with extended polyglutamine tracts self-assemble into amyloid-like fibrillar aggregates. Elucidating the fibril formation mechanism is critical for understanding Huntington's disease pathology and for developing novel therapeutic strategies. Here, we performed systematic experimental and theoretical studies to examine the self-assembly of an aggregation-prone N-terminal HTT exon-1 fragment with 49 glutamines (Ex1Q49). Using high-resolution imaging techniques such as electron microscopy and atomic force microscopy, we show that Ex1Q49 fragments in cell-free assays spontaneously convert into large, highly complex bundles of amyloid fibrils with multiple ends and fibril branching points. Furthermore, we present experimental evidence that two nucleation mechanisms control spontaneous Ex1Q49 fibrillogenesis: (1) a relatively slow primary fibril-independent nucleation process, which involves the spontaneous formation of aggregation-competent fibrillary structures, and (2) a fast secondary fibril-dependent nucleation process, which involves nucleated branching and promotes the rapid assembly of highly complex fibril bundles with multiple ends. The proposed aggregation mechanism is supported by studies with the small molecule O4, which perturbs early events in the aggregation cascade and delays Ex1Q49 fibril assembly, comprehensive mathematical and computational modeling studies, and seeding experiments with small, preformed fibrillar Ex1Q49 aggregates that promote the assembly of amyloid fibrils. Together, our results suggest that nucleated branching in vitro plays a critical role in the formation of complex fibrillar HTT exon-1 aggregates with multiple ends.
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Affiliation(s)
- Anne S Wagner
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Antonio Z Politi
- Mathematical Modelling of Cellular Processes, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Anne Ast
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Kenny Bravo-Rodriguez
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 2, 45470 Mülheim an der Ruhr, Germany; Computational Biochemistry, University Duisburg-Essen, Universitätsstr. 2, 45141 Essen, Germany
| | - Katharina Baum
- Mathematical Modelling of Cellular Processes, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Alexander Buntru
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Nadine U Strempel
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Lydia Brusendorf
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Christian Hänig
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Annett Boeddrich
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Stephanie Plassmann
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Konrad Klockmeier
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Juan M Ramirez-Anguita
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 2, 45470 Mülheim an der Ruhr, Germany
| | - Elsa Sanchez-Garcia
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 2, 45470 Mülheim an der Ruhr, Germany; Computational Biochemistry, University Duisburg-Essen, Universitätsstr. 2, 45141 Essen, Germany
| | - Jana Wolf
- Mathematical Modelling of Cellular Processes, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
| | - Erich E Wanker
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
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30
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Wetzel R, Chemuru S, Misra P, Kodali R, Mukherjee S, Kar K. An Aggregate Weight-Normalized Thioflavin-T Measurement Scale for Characterizing Polymorphic Amyloids and Assembly Intermediates. Methods Mol Biol 2018; 1777:121-144. [PMID: 29744831 DOI: 10.1007/978-1-4939-7811-3_6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The red shift in the fluorescence excitation spectra of thioflavin dyes upon binding to fibrils has been a boon to the amyloid field, offering simple and effective methods for the qualitative detection of amyloid in tissue samples and for quantitation of particular fibril preparations with gravimetric linearity. The quantitative aspect of the thioflavin T (ThT) response, however, comes with an important caveat that bestows both significant limitations and great untapped power. It is now well established that amyloid fibrils of different proteins, as well as polymorphic fibrils of the same protein, can exhibit vastly different ThT fluorescence intensities for the same weight concentration of aggregates. Furthermore, the aggregated intermediates commonly observed in amyloid assembly reactions can exhibit aggregate weight-normalized (AWN) ThT fluorescence intensities that vary from essentially zero through a wide range of intermediate values before reaching the intensity of homogeneous, mature amyloid. These features make it very difficult to quantitatively interpret, without additional data, the time-dependent development of ThT fluorescence intensity in an assembly reaction. In this chapter, we describe a method for coupling ex situ ThT fluorescence determinations with an analytical HPLC supported sedimentation assay (also described in detail) that can provide significant new insights into amyloid assembly reactions. The time dependent aggregation data provided by the sedimentation assay reveals a time course of aggregation that is largely independent of aggregate properties. In addition, the combination of these data with ThT measurements of the same reaction time points reveals important aspects of average aggregate structure at each time point. Examples of the use and potential value of AWN-ThT measurements during amyloid assembly Aβ and polyglutamine peptides are provided.
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Affiliation(s)
- Ronald Wetzel
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Saketh Chemuru
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
| | - Pinaki Misra
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Ravi Kodali
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA, USA
| | - Smita Mukherjee
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- The Wharton School, University of Pennsylvania, Philadelphia, PA, USA
| | - Karunakar Kar
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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31
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Warner JB, Ruff KM, Tan PS, Lemke EA, Pappu RV, Lashuel HA. Monomeric Huntingtin Exon 1 Has Similar Overall Structural Features for Wild-Type and Pathological Polyglutamine Lengths. J Am Chem Soc 2017; 139:14456-14469. [PMID: 28937758 PMCID: PMC5677759 DOI: 10.1021/jacs.7b06659] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Indexed: 12/22/2022]
Abstract
Huntington's disease is caused by expansion of a polyglutamine (polyQ) domain within exon 1 of the huntingtin gene (Httex1). The prevailing hypothesis is that the monomeric Httex1 protein undergoes sharp conformational changes as the polyQ length exceeds a threshold of 36-37 residues. Here, we test this hypothesis by combining novel semi-synthesis strategies with state-of-the-art single-molecule Förster resonance energy transfer measurements on biologically relevant, monomeric Httex1 proteins of five different polyQ lengths. Our results, integrated with atomistic simulations, negate the hypothesis of a sharp, polyQ length-dependent change in the structure of monomeric Httex1. Instead, they support a continuous global compaction with increasing polyQ length that derives from increased prominence of the globular polyQ domain. Importantly, we show that monomeric Httex1 adopts tadpole-like architectures for polyQ lengths below and above the pathological threshold. Our results suggest that higher order homotypic and/or heterotypic interactions within distinct sub-populations of neurons, which are inevitable at finite cellular concentrations, are likely to be the main source of sharp polyQ length dependencies of HD.
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Affiliation(s)
- John B. Warner
- Laboratory
of Molecular and Chemical Biology of Neurodegeneration, Brain Mind
Institute, Station 19, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Kiersten M. Ruff
- Department
of Biomedical Engineering and Center for Biological Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Piau Siong Tan
- Structural
and Computational Biology Unit, Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Edward A. Lemke
- Structural
and Computational Biology Unit, Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Rohit V. Pappu
- Department
of Biomedical Engineering and Center for Biological Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Hilal A. Lashuel
- Laboratory
of Molecular and Chemical Biology of Neurodegeneration, Brain Mind
Institute, Station 19, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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32
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Branco-Santos J, Herrera F, Poças GM, Pires-Afonso Y, Giorgini F, Domingos PM, Outeiro TF. Protein phosphatase 1 regulates huntingtin exon 1 aggregation and toxicity. Hum Mol Genet 2017; 26:3763-3775. [DOI: 10.1093/hmg/ddx260] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 06/30/2017] [Indexed: 12/31/2022] Open
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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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Kuiper EFE, de Mattos EP, Jardim LB, Kampinga HH, Bergink S. Chaperones in Polyglutamine Aggregation: Beyond the Q-Stretch. Front Neurosci 2017; 11:145. [PMID: 28386214 PMCID: PMC5362620 DOI: 10.3389/fnins.2017.00145] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/08/2017] [Indexed: 01/12/2023] Open
Abstract
Expanded polyglutamine (polyQ) stretches in at least nine unrelated proteins lead to inherited neuronal dysfunction and degeneration. The expansion size in all diseases correlates with age at onset (AO) of disease and with polyQ protein aggregation, indicating that the expanded polyQ stretch is the main driving force for the disease onset. Interestingly, there is marked interpatient variability in expansion thresholds for a given disease. Between different polyQ diseases the repeat length vs. AO also indicates the existence of modulatory effects on aggregation of the upstream and downstream amino acid sequences flanking the Q expansion. This can be either due to intrinsic modulation of aggregation by the flanking regions, or due to differential interaction with other proteins, such as the components of the cellular protein quality control network. Indeed, several lines of evidence suggest that molecular chaperones have impact on the handling of different polyQ proteins. Here, we review factors differentially influencing polyQ aggregation: the Q-stretch itself, modulatory flanking sequences, interaction partners, cleavage of polyQ-containing proteins, and post-translational modifications, with a special focus on the role of molecular chaperones. By discussing typical examples of how these factors influence aggregation, we provide more insight on the variability of AO between different diseases as well as within the same polyQ disorder, on the molecular level.
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Affiliation(s)
- E F E Kuiper
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Eduardo P de Mattos
- Department of Cell Biology, University Medical Center Groningen, University of GroningenGroningen, Netherlands; Programa de Pós-Graduação em Genética e Biologia Molecular, Department of Genetics, Universidade Federal do Rio Grande do SulPorto Alegre, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto AlegrePorto Alegre, Brazil
| | - Laura B Jardim
- Programa de Pós-Graduação em Genética e Biologia Molecular, Department of Genetics, Universidade Federal do Rio Grande do SulPorto Alegre, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto AlegrePorto Alegre, Brazil; Departamento de Medicina Interna, Universidade Federal do Rio Grande do SulPorto Alegre, Brazil
| | - Harm H Kampinga
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Steven Bergink
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
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Adegbuyiro A, Sedighi F, Pilkington AW, Groover S, Legleiter J. Proteins Containing Expanded Polyglutamine Tracts and Neurodegenerative Disease. Biochemistry 2017; 56:1199-1217. [PMID: 28170216 DOI: 10.1021/acs.biochem.6b00936] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Several hereditary neurological and neuromuscular diseases are caused by an abnormal expansion of trinucleotide repeats. To date, there have been 10 of these trinucleotide repeat disorders associated with an expansion of the codon CAG encoding glutamine (Q). For these polyglutamine (polyQ) diseases, there is a critical threshold length of the CAG repeat required for disease, and further expansion beyond this threshold is correlated with age of onset and symptom severity. PolyQ expansion in the translated proteins promotes their self-assembly into a variety of oligomeric and fibrillar aggregate species that accumulate into the hallmark proteinaceous inclusion bodies associated with each disease. Here, we review aggregation mechanisms of proteins with expanded polyQ-tracts, structural consequences of expanded polyQ ranging from monomers to fibrillar aggregates, the impact of protein context and post-translational modifications on aggregation, and a potential role for lipid membranes in aggregation. As the pathogenic mechanisms that underlie these disorders are often classified as either a gain of toxic function or loss of normal protein function, some toxic mechanisms associated with mutant polyQ tracts will also be discussed.
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Affiliation(s)
- Adewale Adegbuyiro
- The C. Eugene Bennett Department of Chemistry, 217 Clark Hall, West Virginia University , Morgantown, West Virginia 26506, United States
| | - Faezeh Sedighi
- The C. Eugene Bennett Department of Chemistry, 217 Clark Hall, West Virginia University , Morgantown, West Virginia 26506, United States
| | - Albert W Pilkington
- The C. Eugene Bennett Department of Chemistry, 217 Clark Hall, West Virginia University , Morgantown, West Virginia 26506, United States
| | - Sharon Groover
- The C. Eugene Bennett Department of Chemistry, 217 Clark Hall, West Virginia University , Morgantown, West Virginia 26506, United States
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, 217 Clark Hall, West Virginia University , Morgantown, West Virginia 26506, United States.,Blanchette Rockefeller Neurosciences Institute, Robert C. Byrd Health Sciences Center, P.O. Box 9304, West Virginia University , Morgantown, West Virginia 26506, United States.,NanoSAFE, P.O. Box 6223, West Virginia University , Morgantown, West Virginia 26506, United States
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36
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Totzeck F, Andrade-Navarro MA, Mier P. The Protein Structure Context of PolyQ Regions. PLoS One 2017; 12:e0170801. [PMID: 28125688 PMCID: PMC5268486 DOI: 10.1371/journal.pone.0170801] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 01/11/2017] [Indexed: 11/19/2022] Open
Abstract
Proteins containing glutamine repeats (polyQ) are known to be structurally unstable. Abnormal expansion of polyQ in some proteins exceeding a certain threshold leads to neurodegenerative disease, a symptom of which are protein aggregates. This has led to extensive research of the structure of polyQ stretches. However, the accumulation of contradictory results suggests that protein context might be of importance. Here we aimed to evaluate the structural context of polyQ regions in proteins by analysing the secondary structure of polyQ proteins and their homologs. The results revealed that the secondary structure in polyQ vicinity is predominantly random coil or helix. Importantly, the regions surrounding the polyQ are often not solved in 3D structures. In the few cases where the point of insertion of the polyQ was mapped to a full protein, we observed that these are always located in the surface of the protein. The findings support the hypothesis that polyQ might serve to extend coiled coils at their C-terminus in highly disordered regions involved in protein-protein interactions.
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Affiliation(s)
- Franziska Totzeck
- Faculty of Biology, Johannes Gutenberg University Mainz, Gresemundweg 2, Mainz, Germany
| | - Miguel A. Andrade-Navarro
- Faculty of Biology, Johannes Gutenberg University Mainz, Gresemundweg 2, Mainz, Germany
- Institute of Molecular Biology, Ackermannweg 4, Mainz, Germany
| | - Pablo Mier
- Faculty of Biology, Johannes Gutenberg University Mainz, Gresemundweg 2, Mainz, Germany
- Institute of Molecular Biology, Ackermannweg 4, Mainz, Germany
- * E-mail:
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Kar K, Baker MA, Lengyel GA, Hoop CL, Kodali R, Byeon IJ, Horne WS, van der Wel PCA, Wetzel R. Backbone Engineering within a Latent β-Hairpin Structure to Design Inhibitors of Polyglutamine Amyloid Formation. J Mol Biol 2016; 429:308-323. [PMID: 27986569 DOI: 10.1016/j.jmb.2016.12.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/03/2016] [Accepted: 12/07/2016] [Indexed: 11/28/2022]
Abstract
Candidates for the toxic molecular species in the expanded polyglutamine (polyQ) repeat diseases range from various types of aggregates to "misfolded" monomers. One way to vet these candidates is to develop mutants that restrict conformational landscapes. Previously, we inserted two self-complementary β-hairpin enhancing motifs into a short polyQ sequence to generate a mutant, here called "βHP," that exhibits greatly improved amyloid nucleation without measurably enhancing β-structure in the monomer ensemble. We extend these studies here by introducing single-backbone H-bond impairing modifications αN-methyl Gln or l-Pro at key positions within βHP. Modifications predicted to allow formation of a fully H-bonded β-hairpin at the fibril edge while interfering with H-bonding to the next incoming monomer exhibit poor amyloid formation and act as potent inhibitors in trans of simple polyQ peptide aggregation. In contrast, a modification that disrupts intra-β-hairpin H-bonding within βHP, while also aggregating poorly, is ineffective at inhibiting amyloid formation in trans. The inhibitors constitute a dynamic version of the edge-protection negative design strategy used in protein evolution to limit unwanted protein aggregation. Our data support a model in which polyQ peptides containing strong β-hairpin encouraging motifs only rarely form β-hairpin conformations in the monomer ensemble, but nonetheless take on such conformations at key steps during amyloid formation. The results provide insights into polyQ solution structure and fibril formation while also suggesting an approach to the design of inhibitors of polyQ amyloid growth that focuses on conformational requirements for fibril and nucleus elongation.
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Affiliation(s)
- Karunakar Kar
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Matthew A Baker
- Department of Chemistry, Kenneth P. Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - George A Lengyel
- Department of Chemistry, Kenneth P. Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Cody L Hoop
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Ravindra Kodali
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - In-Ja Byeon
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - W Seth Horne
- Department of Chemistry, Kenneth P. Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Patrick C A van der Wel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Ronald Wetzel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
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Rapid α-oligomer formation mediated by the Aβ C terminus initiates an amyloid assembly pathway. Nat Commun 2016; 7:12419. [PMID: 27546208 PMCID: PMC4996947 DOI: 10.1038/ncomms12419] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 06/30/2016] [Indexed: 11/09/2022] Open
Abstract
Since early oligomeric intermediates in amyloid assembly are often transient and difficult to distinguish, characterize and quantify, the mechanistic basis of the initiation of spontaneous amyloid growth is often opaque. We describe here an approach to the analysis of the Aβ aggregation mechanism that uses Aβ-polyglutamine hybrid peptides designed to retard amyloid maturation and an adjusted thioflavin intensity scale that reveals structural features of aggregation intermediates. The results support an aggregation initiation mechanism for Aβ-polyQ hybrids, and by extension for full-length Aβ peptides, in which a modular Aβ C-terminal segment mediates rapid, non-nucleated formation of α-helical oligomers. The resulting high local concentration of tethered amyloidogenic segments within these α-oligomers facilitates transition to a β-oligomer population that, via further remodelling and/or elongation steps, ultimately generates mature amyloid. Consistent with this mechanism, an engineered Aβ C-terminal fragment delays aggregation onset by Aβ-polyglutamine peptides and redirects assembly of Aβ42 fibrils. The elucidation of amyloid nucleation mechanisms remains challenging as early oligomeric intermediates are transient and difficult to distinguish. Here the authors use Aβ- polyglutamine hybrid peptides designed to slow and limit amyloid maturation to provide insights into the structures of Aβ self-assembly intermediates.
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