1
|
Cariulo C, Martufi P, Verani M, Toledo-Sherman L, Lee R, Dominguez C, Petricca L, Caricasole A. IKBKB reduces huntingtin aggregation by phosphorylating serine 13 via a non-canonical IKK pathway. Life Sci Alliance 2023; 6:e202302006. [PMID: 37553253 PMCID: PMC10410066 DOI: 10.26508/lsa.202302006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 08/10/2023] Open
Abstract
N-terminal phosphorylation at residues T3 and S13 is believed to have important beneficial implications for the biological and pathological properties of mutant huntingtin, where inhibitor of nuclear factor kappa B kinase subunit beta (IKBKB) was identified as a candidate regulator of huntingtin N-terminal phosphorylation. The paucity of mechanistic information on IKK pathways, together with the lack of sensitive methods to quantify endogenous huntingtin phosphorylation, prevented detailed study of the role of IKBKB in Huntington's disease. Using novel ultrasensitive assays, we demonstrate that IKBKB can regulate endogenous S13 huntingtin phosphorylation in a manner, dependent on its kinase activity and known regulators. We found that the ability of IKBKB to phosphorylate endogenous huntingtin S13 is mediated through a non-canonical interferon regulatory factor3-mediated IKK pathway, distinct from the established involvement of IKBKB in mutant huntingtin's pathological mechanisms mediated via the canonical pathway. Furthermore, increased huntingtin S13 phosphorylation by IKBKB resulted in decreased aggregation of mutant huntingtin in cells, again dependent on its kinase activity. These findings point to a non-canonical IKK pathway linking S13 huntingtin phosphorylation to the pathological properties of mutant huntingtin aggregation, thought to be significant to Huntington's disease.
Collapse
Affiliation(s)
- Cristina Cariulo
- Neuroscience Unit, Translational and Discovery Research Department, IRBM S.p.A., Rome, Italy
| | - Paola Martufi
- Neuroscience Unit, Translational and Discovery Research Department, IRBM S.p.A., Rome, Italy
| | - Margherita Verani
- Neuroscience Unit, Translational and Discovery Research Department, IRBM S.p.A., Rome, Italy
| | - Leticia Toledo-Sherman
- Rainwatercf.org Tau Consortium, Rainwater Charitable Foundation, Fort Worth, TX, USA
- UCLA, Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA
| | - Ramee Lee
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | | | - Lara Petricca
- Neuroscience Unit, Translational and Discovery Research Department, IRBM S.p.A., Rome, Italy
| | - Andrea Caricasole
- Neuroscience Unit, Translational and Discovery Research Department, IRBM S.p.A., Rome, Italy
| |
Collapse
|
2
|
Seefelder M, Klein FAC, Landwehrmeyer B, Fernández-Busnadiego R, Kochanek S. Huntingtin and Its Partner Huntingtin-Associated Protein 40: Structural and Functional Considerations in Health and Disease. J Huntingtons Dis 2022; 11:227-242. [PMID: 35871360 PMCID: PMC9484127 DOI: 10.3233/jhd-220543] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Since the discovery of the mutation causing Huntington’s disease (HD) in 1993, it has been debated whether an expanded polyglutamine (polyQ) stretch affects the properties of the huntingtin (HTT) protein and thus contributes to the pathological mechanisms responsible for HD. Here we review the current knowledge about the structure of HTT, alone (apo-HTT) or in a complex with Huntingtin-Associated Protein 40 (HAP40), the influence of polyQ-length variation on apo-HTT and the HTT-HAP40 complex, and the biology of HAP40. Phylogenetic analyses suggest that HAP40 performs essential functions. Highlighting the relevance of its interaction with HTT, HAP40 is one of the most abundant partners copurifying with HTT and is rapidly degraded, when HTT levels are reduced. As the levels of both proteins decrease during disease progression, HAP40 could also be a biomarker for HD. Whether declining HAP40 levels contribute to disease etiology is an open question. Structural studies have shown that the conformation of apo-HTT is less constrained but resembles that adopted in the HTT-HAP40 complex, which is exceptionally stable because of extensive interactions between HAP40 and the three domains of HTT. The complex— and to some extent apo-HTT— resists fragmentation after limited proteolysis. Unresolved regions of apo-HTT, constituting about 25% of the protein, are the main sites of post-translational modifications and likely have major regulatory functions. PolyQ elongation does not substantially alter the structure of HTT, alone or when associated with HAP40. Particularly, polyQ above the disease length threshold does not induce drastic conformational changes in full-length HTT. Therefore, models of HD pathogenesis stating that polyQ expansion drastically alters HTT properties should be reconsidered.
Collapse
Affiliation(s)
| | | | | | - Rubén Fernández-Busnadiego
- Institute of Neuropathology, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | | |
Collapse
|
3
|
Xu S, Li G, Ye X, Chen D, Chen Z, Xu Z, Daniele M, Tambone S, Ceccacci A, Tomei L, Ye L, Yu Y, Solbach A, Farmer SM, Stimming EF, McAllister G, Marchionini DM, Zhang S. HAP40 is a conserved central regulator of Huntingtin and a potential modulator of Huntington's disease pathogenesis. PLoS Genet 2022; 18:e1010302. [PMID: 35853002 PMCID: PMC9295956 DOI: 10.1371/journal.pgen.1010302] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 06/18/2022] [Indexed: 11/19/2022] Open
Abstract
Perturbation of huntingtin (HTT)'s physiological function is one postulated pathogenic factor in Huntington's disease (HD). However, little is known how HTT is regulated in vivo. In a proteomic study, we isolated a novel ~40kDa protein as a strong binding partner of Drosophila HTT and demonstrated it was the functional ortholog of HAP40, an HTT associated protein shown recently to modulate HTT's conformation but with unclear physiological and pathologic roles. We showed that in both flies and human cells, HAP40 maintained conserved physical and functional interactions with HTT. Additionally, loss of HAP40 resulted in similar phenotypes as HTT knockout. More strikingly, HAP40 strongly affected HTT's stability, as depletion of HAP40 significantly reduced the levels of endogenous HTT protein while HAP40 overexpression markedly extended its half-life. Conversely, in the absence of HTT, the majority of HAP40 protein were degraded, likely through the proteasome. Further, the affinity between HTT and HAP40 was not significantly affected by polyglutamine expansion in HTT, and contrary to an early report, there were no abnormal accumulations of endogenous HAP40 protein in HD cells from mouse HD models or human patients. Lastly, when tested in Drosophila models of HD, HAP40 partially modulated the neurodegeneration induced by full-length mutant HTT while showed no apparent effect on the toxicity of mutant HTT exon 1 fragment. Together, our study uncovers a conserved mechanism governing the stability and in vivo functions of HTT and demonstrates that HAP40 is a central and positive regulator of endogenous HTT. Further, our results support that mutant HTT is toxic regardless of the presence of its partner HAP40, and implicate HAP40 as a potential modulator of HD pathogenesis through its multiplex effect on HTT's function, stability and the potency of mutant HTT's toxicity.
Collapse
Affiliation(s)
- Shiyu Xu
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Gang Li
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Xin Ye
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Dongsheng Chen
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Zhihua Chen
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Zhen Xu
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Moretti Daniele
- Department of Translational and Discovery Research, IRBM SpA, Pomezia (RM), Italy
| | - Sara Tambone
- Department of Translational and Discovery Research, IRBM SpA, Pomezia (RM), Italy
| | - Alessandra Ceccacci
- Department of Translational and Discovery Research, IRBM SpA, Pomezia (RM), Italy
| | - Licia Tomei
- Department of Translational and Discovery Research, IRBM SpA, Pomezia (RM), Italy
| | - Lili Ye
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Yue Yu
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
- Programs in Genetics and Epigenetics and Neuroscience, The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences (MD Anderson UTHealth GSBS), Houston, Texas, United States of America
| | - Amanda Solbach
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
- Programs in Genetics and Epigenetics and Neuroscience, The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences (MD Anderson UTHealth GSBS), Houston, Texas, United States of America
| | - Stephen M. Farmer
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
- Program in Biochemistry and Cell Biology, The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences (MD Anderson UTHealth GSBS), Houston, Texas, United States of America
| | - Erin Furr Stimming
- Department of Neurology, HDSA Center of Excellence, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - George McAllister
- CHDI Management/CHDI Foundation, 350 Seventh Ave, New York, New York, United States of America
| | - Deanna M. Marchionini
- CHDI Management/CHDI Foundation, 350 Seventh Ave, New York, New York, United States of America
| | - Sheng Zhang
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
- Programs in Genetics and Epigenetics and Neuroscience, The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences (MD Anderson UTHealth GSBS), Houston, Texas, United States of America
- Department of Neurobiology and Anatomy, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| |
Collapse
|
4
|
Kim H, Hyun KG, Lloret A, Seong IS, Song JJ. Purification of full-length recombinant human huntingtin proteins with allelic series of polyglutamine lengths. STAR Protoc 2021; 2:100886. [PMID: 34746859 PMCID: PMC8551504 DOI: 10.1016/j.xpro.2021.100886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the polyglutamine (polyQ) expansion in huntingtin (HTT) protein. The challenge of obtaining full-length HTT proteins with high purity limits the understanding of the HTT protein function. Here, we provide a protocol to generate and purify full-length recombinant human HTT proteins with various polyQ lengths, which is key to investigate the biochemical function of HTT proteins and the molecular mechanism underlying HD pathology. For complete details on the use and execution of this protocol, please refer to Jung et al. (2020).
Collapse
Affiliation(s)
- Hyeongju Kim
- Department of Biological Sciences, KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
| | - Kyung-gi Hyun
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Alejandro Lloret
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Ihn Sik Seong
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Ji-Joon Song
- Department of Biological Sciences, KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
| |
Collapse
|
5
|
Harding RJ, Deme JC, Hevler JF, Tamara S, Lemak A, Cantle JP, Szewczyk MM, Begeja N, Goss S, Zuo X, Loppnau P, Seitova A, Hutchinson A, Fan L, Truant R, Schapira M, Carroll JB, Heck AJR, Lea SM, Arrowsmith CH. Huntingtin structure is orchestrated by HAP40 and shows a polyglutamine expansion-specific interaction with exon 1. Commun Biol 2021; 4:1374. [PMID: 34880419 PMCID: PMC8654980 DOI: 10.1038/s42003-021-02895-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 11/09/2021] [Indexed: 12/14/2022] Open
Abstract
Huntington's disease results from expansion of a glutamine-coding CAG tract in the huntingtin (HTT) gene, producing an aberrantly functioning form of HTT. Both wildtype and disease-state HTT form a hetero-dimer with HAP40 of unknown functional relevance. We demonstrate in vivo and in cell models that HTT and HAP40 cellular abundance are coupled. Integrating data from a 2.6 Å cryo-electron microscopy structure, cross-linking mass spectrometry, small-angle X-ray scattering, and modeling, we provide a near-atomic-level view of HTT, its molecular interaction surfaces and compacted domain architecture, orchestrated by HAP40. Native mass spectrometry reveals a remarkably stable hetero-dimer, potentially explaining the cellular inter-dependence of HTT and HAP40. The exon 1 region of HTT is dynamic but shows greater conformational variety in the polyglutamine expanded mutant than wildtype exon 1. Our data provide a foundation for future functional and drug discovery studies targeting Huntington's disease and illuminate the structural consequences of HTT polyglutamine expansion.
Collapse
Affiliation(s)
- Rachel J Harding
- Structural Genomics Consortium, University of Toronto, Toronto, ON, M5G 1L7, Canada.
| | - Justin C Deme
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
- Central Oxford Structural Molecular Imaging Centre, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Johannes F Hevler
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- Netherlands Proteomics Center, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Sem Tamara
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- Netherlands Proteomics Center, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Alexander Lemak
- Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, ON, M5G 1L7, Canada
| | - Jeffrey P Cantle
- Behavioral Neuroscience Program, Department of Psychology, Western Washington University, Bellingham, WA, 98225, USA
| | - Magdalena M Szewczyk
- Structural Genomics Consortium, University of Toronto, Toronto, ON, M5G 1L7, Canada
| | - Nola Begeja
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Siobhan Goss
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Xiaobing Zuo
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Peter Loppnau
- Structural Genomics Consortium, University of Toronto, Toronto, ON, M5G 1L7, Canada
| | - Alma Seitova
- Structural Genomics Consortium, University of Toronto, Toronto, ON, M5G 1L7, Canada
| | - Ashley Hutchinson
- Structural Genomics Consortium, University of Toronto, Toronto, ON, M5G 1L7, Canada
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, SAXS Core of NCI, National Institutes of Health, Frederick, MD, 21701, USA
| | - Ray Truant
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Matthieu Schapira
- Structural Genomics Consortium, University of Toronto, Toronto, ON, M5G 1L7, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Jeffrey B Carroll
- Behavioral Neuroscience Program, Department of Psychology, Western Washington University, Bellingham, WA, 98225, USA
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- Netherlands Proteomics Center, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Susan M Lea
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
- Central Oxford Structural Molecular Imaging Centre, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Cheryl H Arrowsmith
- Structural Genomics Consortium, University of Toronto, Toronto, ON, M5G 1L7, Canada.
- Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, ON, M5G 1L7, Canada.
| |
Collapse
|
6
|
Kolla R, Gopinath P, Ricci J, Reif A, Rostami I, Lashuel HA. A New Chemoenzymatic Semisynthetic Approach Provides Insight into the Role of Phosphorylation beyond Exon1 of Huntingtin and Reveals N-Terminal Fragment Length-Dependent Distinct Mechanisms of Aggregation. J Am Chem Soc 2021; 143:9798-9812. [PMID: 34161085 DOI: 10.1021/jacs.1c03108] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Huntington's disease is a neurodegenerative disorder caused by the expansion of a polyglutamine repeat (>36Q) in the N-terminal domain of the huntingtin protein (Htt), which renders the protein or fragments thereof more prone to aggregate and form inclusions. Although several Htt N-terminal fragments of different lengths have been identified within Htt inclusions, most studies on the mechanisms, sequence, and structural determinants of Htt aggregation have focused on the Httexon1 (Httex1). Herein, we investigated the aggregation properties of mutant N-terminal Htt fragments of various lengths (Htt171, Htt140, and Htt104) in comparison to mutant Httex1 (mHttex1). We also present a new chemoenzymatic semisynthetic strategy that enables site-specific phosphorylation of Htt beyond Httex1. These advances yielded insights into how post-translational modifications (PTMs) and structured domains beyond Httex1 influence aggregation mechanisms, kinetics, and fibril morphology of longer N-terminal Htt fragments. We demonstrate that phosphorylation at T107 significantly slows the aggregation of mHtt171, whereas phosphorylation at T107 and S116 accelerates the aggregation, underscoring the importance of crosstalk between different PTMs. The mHtt171 proteins aggregate via a different mechanism and form oligomers and fibrillar aggregates with morphological properties that are distinct from that of mHttex1. These observations suggest that different N-terminal fragments could have distinct aggregation mechanisms and that a single polyQ-targeting antiaggregation strategy may not effectively inhibit the aggregation of all N-terminal Htt fragments. Finally, our results underscore the need for further studies to investigate the aggregation mechanisms of Htt fragments and how the various fragments interact with each other and influence Htt toxicity and disease progression.
Collapse
Affiliation(s)
- Rajasekhar Kolla
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, School of Life Sciences, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Pushparathinam Gopinath
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, School of Life Sciences, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jonathan Ricci
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, School of Life Sciences, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Andreas Reif
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, School of Life Sciences, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Iman Rostami
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, School of Life Sciences, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Hilal A Lashuel
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, School of Life Sciences, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| |
Collapse
|
7
|
Huang B, Guo Q, Niedermeier ML, Cheng J, Engler T, Maurer M, Pautsch A, Baumeister W, Stengel F, Kochanek S, Fernández-Busnadiego R. Pathological polyQ expansion does not alter the conformation of the Huntingtin-HAP40 complex. Structure 2021; 29:804-809.e5. [PMID: 33909994 DOI: 10.1016/j.str.2021.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/23/2021] [Accepted: 04/08/2021] [Indexed: 01/12/2023]
Abstract
The abnormal amplification of a CAG repeat in the gene coding for huntingtin (HTT) leads to Huntington's disease (HD). At the protein level, this translates into the expansion of a polyglutamine (polyQ) stretch located at the HTT N terminus, which renders HTT aggregation prone by unknown mechanisms. Here we investigated the effects of polyQ expansion on HTT in a complex with its stabilizing interaction partner huntingtin-associated protein 40 (HAP40). Surprisingly, our comprehensive biophysical, crosslinking mass spectrometry and cryo-EM experiments revealed no major differences in the conformation of HTT-HAP40 complexes of various polyQ length, including 17QHTT-HAP40 (wild type), 46QHTT-HAP40 (typical polyQ length in HD patients), and 128QHTT-HAP40 (extreme polyQ length). Thus, HTT polyQ expansion does not alter the global conformation of HTT when associated with HAP40.
Collapse
Affiliation(s)
- Bin Huang
- Department of Gene Therapy, Ulm University, 89081, Ulm, Germany
| | - Qiang Guo
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, 100871 Beijing, China
| | - Marie L Niedermeier
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany; Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Jingdong Cheng
- Gene Center, Department of Biochemistry and Center for Integrated Protein Science Munich, Ludwig-Maximilians University, 81377 Munich, Germany
| | - Tatjana Engler
- Department of Gene Therapy, Ulm University, 89081, Ulm, Germany
| | - Melanie Maurer
- Department of Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397 Biberach an der Riß, Germany
| | - Alexander Pautsch
- Department of Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397 Biberach an der Riß, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Florian Stengel
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany; Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany.
| | - Stefan Kochanek
- Department of Gene Therapy, Ulm University, 89081, Ulm, Germany.
| | - Rubén Fernández-Busnadiego
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Institute of Neuropathology, University Medical Center Göttingen, 37099 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37075 Göttingen, Germany.
| |
Collapse
|
8
|
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.
Collapse
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;
| |
Collapse
|
9
|
Analysis of mutant and total huntingtin expression in Huntington's disease murine models. Sci Rep 2020; 10:22137. [PMID: 33335120 PMCID: PMC7746729 DOI: 10.1038/s41598-020-78790-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/27/2020] [Indexed: 11/17/2022] Open
Abstract
Huntington’s disease (HD) is a monogenetic neurodegenerative disorder that is caused by the expansion of a polyglutamine region within the huntingtin (HTT) protein, but there is still an incomplete understanding of the molecular mechanisms that drive pathology. Expression of the mutant form of HTT is a key aspect of diseased tissues, and the most promising therapeutic approaches aim to lower expanded HTT levels. Consequently, the investigation of HTT expression in time and in multiple tissues, with assays that accurately quantify expanded and non-expanded HTT, are required to delineate HTT homeostasis and to best design and interpret pharmacodynamic readouts for HTT lowering therapeutics. Here we evaluate mutant polyglutamine-expanded (mHTT) and polyglutamine-independent HTT specific immunoassays for validation in human HD and control fibroblasts and use to elucidate the CSF/brain and peripheral tissue expression of HTT in preclinical HD models.
Collapse
|
10
|
The evolution of the huntingtin-associated protein 40 (HAP40) in conjunction with huntingtin. BMC Evol Biol 2020; 20:162. [PMID: 33297953 PMCID: PMC7725122 DOI: 10.1186/s12862-020-01705-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 10/20/2020] [Indexed: 11/24/2022] Open
Abstract
Background The huntingtin-associated protein 40 (HAP40) abundantly interacts with huntingtin (HTT), the protein that is altered in Huntington’s disease (HD). Therefore, we analysed the evolution of HAP40 and its interaction with HTT. Results We found that in amniotes HAP40 is encoded by a single-exon gene, whereas in all other organisms it is expressed from multi-exon genes. HAP40 co-occurs with HTT in unikonts, including filastereans such as Capsaspora owczarzaki and the amoebozoan Dictyostelium discoideum, but both proteins are absent from fungi. Outside unikonts, a few species, such as the free-living amoeboflagellate Naegleria gruberi, contain putative HTT and HAP40 orthologs. Biochemically we show that the interaction between HTT and HAP40 extends to fish, and bioinformatic analyses provide evidence for evolutionary conservation of this interaction. The closest homologue of HAP40 in current protein databases is the family of soluble N-ethylmaleimide-sensitive factor attachment proteins (SNAPs). Conclusion Our results indicate that the transition from a multi-exon to a single-exon gene appears to have taken place by retroposition during the divergence of amphibians and amniotes, followed by the loss of the parental multi-exon gene. Furthermore, it appears that the two proteins probably originated at the root of eukaryotes. Conservation of the interaction between HAP40 and HTT and their likely coevolution strongly indicate functional importance of this interaction.
Collapse
|
11
|
Jung T, Shin B, Tamo G, Kim H, Vijayvargia R, Leitner A, Marcaida MJ, Astorga-Wells J, Jung R, Aebersold R, Peraro MD, Hebert H, Seong IS, Song JJ. The Polyglutamine Expansion at the N-Terminal of Huntingtin Protein Modulates the Dynamic Configuration and Phosphorylation of the C-Terminal HEAT Domain. Structure 2020; 28:1035-1050.e8. [PMID: 32668197 PMCID: PMC11059206 DOI: 10.1016/j.str.2020.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 04/01/2020] [Accepted: 06/23/2020] [Indexed: 11/15/2022]
Abstract
The polyQ expansion in huntingtin protein (HTT) is the prime cause of Huntington's disease (HD). The recent cryoelectron microscopy (cryo-EM) structure of HTT-HAP40 complex provided the structural information on its HEAT-repeat domains. Here, we present analyses of the impact of polyQ length on the structure and function of HTT via an integrative structural and biochemical approach. The cryo-EM analysis of normal (Q23) and disease (Q78) type HTTs shows that the structures of apo HTTs significantly differ from the structure of HTT in a HAP40 complex and that the polyQ expansion induces global structural changes in the relative movements among the HTT domains. In addition, we show that the polyQ expansion alters the phosphorylation pattern across HTT and that Ser2116 phosphorylation in turn affects the global structure and function of HTT. These results provide a molecular basis for the effect of the polyQ segment on HTT structure and activity, which may be important for HTT pathology.
Collapse
Affiliation(s)
- Taeyang Jung
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), KI for the BioCentury, Daejeon 34141, Korea; School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, 141 52 Huddinge, Sweden; Department of Biosciences and Nutrition, Karolinska Institutet, 141 83 Huddinge, Sweden
| | - Baehyun Shin
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Giorgio Tamo
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Hyeongju Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), KI for the BioCentury, Daejeon 34141, Korea
| | - Ravi Vijayvargia
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Alexander Leitner
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Maria J Marcaida
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Juan Astorga-Wells
- Department of Medical Biochemistry & Biophysics, Karolinska Institutet, 171 65 Solna, Sweden; HDxperts AB, 183 48 Täby, Sweden
| | - Roy Jung
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland; Faculty of Science, University of Zürich, Zürich, Switzerland
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
| | - Hans Hebert
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, 141 52 Huddinge, Sweden; Department of Biosciences and Nutrition, Karolinska Institutet, 141 83 Huddinge, Sweden.
| | - Ihn Sik Seong
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Harvard Medical School, Boston, MA 02114, USA.
| | - Ji-Joon Song
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), KI for the BioCentury, Daejeon 34141, Korea.
| |
Collapse
|
12
|
Harding RJ, Loppnau P, Ackloo S, Lemak A, Hutchinson A, Hunt B, Holehouse AS, Ho JC, Fan L, Toledo-Sherman L, Seitova A, Arrowsmith CH. Design and characterization of mutant and wildtype huntingtin proteins produced from a toolkit of scalable eukaryotic expression systems. J Biol Chem 2019; 294:6986-7001. [PMID: 30842263 PMCID: PMC6497952 DOI: 10.1074/jbc.ra118.007204] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/19/2019] [Indexed: 12/11/2022] Open
Abstract
The gene mutated in individuals with Huntington's disease (HD) encodes the 348-kDa huntingtin (HTT) protein. Pathogenic HD CAG-expansion mutations create a polyglutamine (polyQ) tract at the N terminus of HTT that expands above a critical threshold of ∼35 glutamine residues. The effect of these HD mutations on HTT is not well understood, in part because it is difficult to carry out biochemical, biophysical, and structural studies of this large protein. To facilitate such studies, here we have generated expression constructs for the scalable production of HTT in multiple eukaryotic expression systems. Our set of HTT expression clones comprised both N- and C-terminally FLAG-tagged HTT constructs with polyQ lengths representative of the general population, HD patients, and juvenile HD patients, as well as the more extreme polyQ expansions used in some HD tissue and animal models. Our expression system yielded milligram quantities of pure recombinant HTT protein, including many of the previously mapped post-translational modifications. We characterized both apo and HTT-HTT-associated protein 40 (HAP40) complex samples produced with this HD resource, demonstrating that this toolkit can be used to generate physiologically meaningful HTT complexes. We further demonstrate that these resources can produce sufficient material for protein-intensive experiments, such as small-angle X-ray scattering, providing biochemical insight into full-length HTT protein structure. The work outlined and the tools generated here lay a foundation for further biochemical and structural work on the HTT protein and for studying its functional interactions with other biomolecules.
Collapse
Affiliation(s)
- Rachel J Harding
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada,
| | - Peter Loppnau
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada
| | - Suzanne Ackloo
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada
| | - Alexander Lemak
- the Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Ashley Hutchinson
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada
| | - Brittany Hunt
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada
| | - Alex S Holehouse
- the Department of Biomedical Engineering and Center for Biological Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130
| | - Jolene C Ho
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada
| | - Lixin Fan
- the Basic Science Program, Frederick National Laboratory for Cancer Research, SAXS Core of NCI, National Institutes of Health, Frederick, Maryland 21701, and
| | | | - Alma Seitova
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada
| | - Cheryl H Arrowsmith
- From the Structural Genomics Consortium, University of Toronto, Ontario M5G 1L7, Canada,
- the Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| |
Collapse
|
13
|
Reindl W, Baldo B, Schulz J, Janack I, Lindner I, Kleinschmidt M, Sedaghat Y, Thiede C, Tillack K, Schmidt C, Cardaun I, Schwagarus T, Herrmann F, Hotze M, Osborne GF, Herrmann S, Weiss A, Zerbinatti C, Bates GP, Bard J, Munoz-Sanjuan I, Macdonald D. Meso scale discovery-based assays for the detection of aggregated huntingtin. PLoS One 2019; 14:e0213521. [PMID: 30913220 PMCID: PMC6435127 DOI: 10.1371/journal.pone.0213521] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 02/24/2019] [Indexed: 12/31/2022] Open
Abstract
Huntington's disease (HD) is a monogenic neurodegenerative disorder caused by an expansion of the CAG trinucleotide repeat domain in the huntingtin (HTT) gene, leading to an expanded poly-glutamine (polyQ) stretch in the HTT protein. This mutant HTT (mHTT) protein is highly prone to intracellular aggregation, causing significant damage and cellular loss in the striatal, cortical, and other regions of the brain. Therefore, modulation of mHTT levels in these brain regions in order to reduce intracellular mHTT and aggregate levels represents a direct approach in the development of HD therapeutics. To this end, assays that can be used to detect changes in HTT levels in biological samples are invaluable tools to assess target engagement and guide dose selection in clinical trials. The Meso Scale Discovery (MSD) ELISA-based assay platform is a robust and sensitive method previously employed for the quantification of HTT. However, the currently available MSD assays for HTT are primarily detecting the monomeric soluble form of the protein, but not aggregated species. In this study, we describe the development of novel MSD assays preferentially detecting mHTT in an aggregated form. Recombinant monomeric HTT(1-97)-Q46, which forms aggregates in a time-dependent manner, was used to characterize the ability of each established assay to distinguish between HTT monomers and HTT in a higher assembly state. Further validation of these assays was performed using brain lysates from R6/2, zQ175 knock-in, and BACHD mouse models, to replicate a previously well-characterized age-dependent increase in brain aggregate signals, as well as a significant reduction of aggregate levels in the striatum following mHTT knockdown with a CAG-directed allele-specific zinc-finger repressor protein (ZFP). Lastly, size exclusion chromatography was used to separate and characterize HTT species from brain tissue lysates to demonstrate specificity of the assays for the fractions containing aggregated HTT. In summary, we demonstrate that the newly developed assays preferentially detect aggregated HTT with improved performance in comparison to previous assay technologies. These assays complement the existing MSD platform assays specific for soluble HTT monomers, allowing for a more comprehensive analysis of disease-relevant HTT species in preclinical models of HD.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Georgina F. Osborne
- Dept. Neurodegenerative Disease, Huntington’s Disease Centre and Dementia Research Institute, Institute of Neurology, University College London, London, United Kingdom
| | | | | | | | - Gillian P. Bates
- Dept. Neurodegenerative Disease, Huntington’s Disease Centre and Dementia Research Institute, Institute of Neurology, University College London, London, United Kingdom
| | - Jonathan Bard
- CHDI Management/CHDI Foundation, Los Angeles, CA, United States of America
| | | | - Douglas Macdonald
- CHDI Management/CHDI Foundation, Los Angeles, CA, United States of America
| |
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
Abstract
Huntingtin (Htt) is a large (348 kDa) protein, essential for embryonic
development and involved in diverse cellular activities such as vesicular
transport, endocytosis, autophagy and transcription regulation1,2.
While an integrative understanding of Htt's biological functions is
lacking, the large number of identified interactors suggests that Htt serves as
a protein-protein interaction hub1,3,4.
Furthermore, Huntington’s disease is caused by a mutation in the Htt
gene, resulting in a pathogenic expansion of a polyglutamine (polyQ) repeat at
the N-terminus of Htt5,6. However, only limited structural
information on Htt is currently available. Here we employed cryo-electron
microscopy (cryo-EM) to determine the structure of full-length human Htt in a
complex with HAP40/F8A7 to 4 Å
resolution. Htt is largely α-helical and consists of three major domains.
The N- and C-terminal domains contain multiple HEAT repeats arranged in a
solenoid fashion. These domains are connected by a smaller bridge domain
containing different types of tandem repeats. HAP40 is also largely
α-helical and has a tetratricopeptide repeat (TPR)-like organization.
HAP40 binds in a cleft contacting the three Htt domains by hydrophobic and
electrostatic interactions, thereby stabilizing Htt conformation. These data
rationalize previous biochemical results and pave the way for an improved
understanding of Htt’s diverse cellular functions.
Collapse
|
16
|
Phosphorylation of huntingtin at residue T3 is decreased in Huntington's disease and modulates mutant huntingtin protein conformation. Proc Natl Acad Sci U S A 2017; 114:E10809-E10818. [PMID: 29162692 PMCID: PMC5740681 DOI: 10.1073/pnas.1705372114] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Posttranslational modifications can have profound effects on the biological and biophysical properties of proteins associated with misfolding and aggregation. However, their detection and quantification in clinical samples and an understanding of the mechanisms underlying the pathological properties of misfolding- and aggregation-prone proteins remain a challenge for diagnostics and therapeutics development. We have applied an ultrasensitive immunoassay platform to develop and validate a quantitative assay for detecting a posttranslational modification (phosphorylation at residue T3) of a protein associated with polyglutamine repeat expansion, namely Huntingtin, and characterized its presence in a variety of preclinical and clinical samples. We find that T3 phosphorylation is greatly reduced in samples from Huntington's disease models and in Huntington's disease patients, and we provide evidence that bona-fide T3 phosphorylation alters Huntingtin exon 1 protein conformation and aggregation properties. These findings have significant implications for both mechanisms of disease pathogenesis and the development of therapeutics and diagnostics for Huntington's disease.
Collapse
|
17
|
Arbez N, Ratovitski T, Roby E, Chighladze E, Stewart JC, Ren M, Wang X, Lavery DJ, Ross CA. Post-translational modifications clustering within proteolytic domains decrease mutant huntingtin toxicity. J Biol Chem 2017; 292:19238-19249. [PMID: 28972180 DOI: 10.1074/jbc.m117.782300] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 09/18/2017] [Indexed: 01/09/2023] Open
Abstract
Huntington's disease (HD) is caused in large part by a polyglutamine expansion within the huntingtin (Htt) protein. Post-translational modifications (PTMs) control and regulate many protein functions and cellular pathways, and PTMs of mutant Htt are likely important modulators of HD pathogenesis. Alterations of selected numbers of PTMs of Htt fragments have been shown to modulate Htt cellular localization and toxicity. In this study, we systematically introduced site-directed alterations in individual phosphorylation and acetylation sites in full-length Htt constructs. The effects of each of these PTM alteration constructs were tested on cell toxicity using our nuclear condensation assay and on mitochondrial viability by measuring mitochondrial potential and size. Using these functional assays in primary neurons, we identified several PTMs whose alteration can block neuronal toxicity and prevent potential loss and swelling of the mitochondria caused by mutant Htt. These PTMs included previously described sites such as serine 116 and newly found sites such as serine 2652 throughout the protein. We found that these functionally relevant sites are clustered in protease-sensitive domains throughout full-length Htt. These findings advance our understanding of the Htt PTM code and its role in HD pathogenesis. Because PTMs are catalyzed by enzymes, the toxicity-modulating Htt PTMs identified here may be promising therapeutic targets for managing HD.
Collapse
Affiliation(s)
- Nicolas Arbez
- From the Division of Neurobiology, Department of Psychiatry and Behavioral Sciences,
| | - Tamara Ratovitski
- From the Division of Neurobiology, Department of Psychiatry and Behavioral Sciences
| | - Elaine Roby
- From the Division of Neurobiology, Department of Psychiatry and Behavioral Sciences
| | - Ekaterine Chighladze
- From the Division of Neurobiology, Department of Psychiatry and Behavioral Sciences
| | - Jacqueline C Stewart
- From the Division of Neurobiology, Department of Psychiatry and Behavioral Sciences
| | - Mark Ren
- the Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853, and
| | - Xiaofang Wang
- From the Division of Neurobiology, Department of Psychiatry and Behavioral Sciences
| | - Daniel J Lavery
- the CHDI Foundation/CHDI Management Inc., Princeton, New Jersey 08540
| | - Christopher A Ross
- From the Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, .,the Department of Neurology and Program in Cellular and Molecular Medicine, and.,the Departments of Pharmacology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| |
Collapse
|
18
|
Ratovitski T, O’Meally RN, Jiang M, Chaerkady R, Chighladze E, Stewart JC, Wang X, Arbez N, Roby E, Alexandris A, Duan W, Vijayvargia R, Seong IS, Lavery DJ, Cole RN, Ross CA. Post-Translational Modifications (PTMs), Identified on Endogenous Huntingtin, Cluster within Proteolytic Domains between HEAT Repeats. J Proteome Res 2017; 16:2692-2708. [PMID: 28653853 PMCID: PMC5560079 DOI: 10.1021/acs.jproteome.6b00991] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Post-translational modifications (PTMs) of proteins regulate various cellular processes. PTMs of polyglutamine-expanded huntingtin (Htt) protein, which causes Huntington's disease (HD), are likely modulators of HD pathogenesis. Previous studies have identified and characterized several PTMs on exogenously expressed Htt fragments, but none of them were designed to systematically characterize PTMs on the endogenous full-length Htt protein. We found that full-length endogenous Htt, which was immunoprecipitated from HD knock-in mouse and human post-mortem brain, is suitable for detection of PTMs by mass spectrometry. Using label-free and mass tag labeling-based approaches, we identified near 40 PTMs, of which half are novel (data are available via ProteomeXchange with identifier PXD005753). Most PTMs were located in clusters within predicted unstructured domains rather than within the predicted α-helical structured HEAT repeats. Using quantitative mass spectrometry, we detected significant differences in the stoichiometry of several PTMs between HD and WT mouse brain. The mass-spectrometry identification and quantitation were verified using phospho-specific antibodies for selected PTMs. To further validate our findings, we introduced individual PTM alterations within full-length Htt and identified several PTMs that can modulate its subcellular localization in striatal cells. These findings will be instrumental in further assembling the Htt PTM framework and highlight several PTMs as potential therapeutic targets for HD.
Collapse
Affiliation(s)
- Tamara Ratovitski
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Robert N. O’Meally
- Mass Spectrometry and Proteomics Facility, Department of Biological Chemistry, Johns Hopkins University School of Medicine, 733 North Broadway Street, Suite 371 BRB, Baltimore, Maryland 21287, United States
| | - Mali Jiang
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Raghothama Chaerkady
- Mass Spectrometry and Proteomics Facility, Department of Biological Chemistry, Johns Hopkins University School of Medicine, 733 North Broadway Street, Suite 371 BRB, Baltimore, Maryland 21287, United States
| | - Ekaterine Chighladze
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Jacqueline C. Stewart
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Xiaofang Wang
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Nicolas Arbez
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Elaine Roby
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Athanasios Alexandris
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
| | - Wenzhen Duan
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
- Department of Neurology and Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, United States
- Departments of Pharmacology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, United States
| | - Ravi Vijayvargia
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department of Neurology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Ihn Sik Seong
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department of Neurology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Daniel J. Lavery
- CHDI Foundation/CHDI Management, Inc., Princeton, New Jersey 08540, United States
| | - Robert N. Cole
- Mass Spectrometry and Proteomics Facility, Department of Biological Chemistry, Johns Hopkins University School of Medicine, 733 North Broadway Street, Suite 371 BRB, Baltimore, Maryland 21287, United States
| | - Christopher A. Ross
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 8-121, Baltimore, Maryland 21287, United States
- Department of Neurology and Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, United States
- Departments of Pharmacology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, United States
| |
Collapse
|
19
|
Daldin M, Fodale V, Cariulo C, Azzollini L, Verani M, Martufi P, Spiezia MC, Deguire SM, Cherubini M, Macdonald D, Weiss A, Bresciani A, Vonsattel JPG, Petricca L, Marsh JL, Gines S, Santimone I, Marano M, Lashuel HA, Squitieri F, Caricasole A. Polyglutamine expansion affects huntingtin conformation in multiple Huntington's disease models. Sci Rep 2017; 7:5070. [PMID: 28698602 PMCID: PMC5505970 DOI: 10.1038/s41598-017-05336-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 06/14/2017] [Indexed: 12/29/2022] Open
Abstract
Conformational changes in disease-associated or mutant proteins represent a key pathological aspect of Huntington’s disease (HD) and other protein misfolding diseases. Using immunoassays and biophysical approaches, we and others have recently reported that polyglutamine expansion in purified or recombinantly expressed huntingtin (HTT) proteins affects their conformational properties in a manner dependent on both polyglutamine repeat length and temperature but independent of HTT protein fragment length. These findings are consistent with the HD mutation affecting structural aspects of the amino-terminal region of the protein, and support the concept that modulating mutant HTT conformation might provide novel therapeutic and diagnostic opportunities. We now report that the same conformational TR-FRET based immunoassay detects polyglutamine- and temperature-dependent changes on the endogenously expressed HTT protein in peripheral tissues and post-mortem HD brain tissue, as well as in tissues from HD animal models. We also find that these temperature- and polyglutamine-dependent conformational changes are sensitive to bona-fide phosphorylation on S13 and S16 within the N17 domain of HTT. These findings provide key clinical and preclinical relevance to the conformational immunoassay, and provide supportive evidence for its application in the development of therapeutics aimed at correcting the conformation of polyglutamine-expanded proteins as well as the pharmacodynamics readouts to monitor their efficacy in preclinical models and in HD patients.
Collapse
Affiliation(s)
- Manuel Daldin
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | - Valentina Fodale
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy.,IRBM Promidis, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | - Cristina Cariulo
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | - Lucia Azzollini
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy.,IRBM Promidis, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | - Margherita Verani
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy.,IRBM Promidis, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | - Paola Martufi
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | | | - Sean M Deguire
- 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
| | - Marta Cherubini
- Departamento de Ciencias Biomedicas, Facultat de Medicina, Instituto de Neurociencias, Universitat de Barcelona, Barcelona, Spain
| | | | - Andreas Weiss
- IRBM Promidis, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy.,Evotec AG, Manfred Eigen Campus, Hamburg, Germany
| | - Alberto Bresciani
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | - Jean-Paul Gerard Vonsattel
- Taub Institute for Research on Alzheimer's disease and the Aging Brain, Columbia University Medical Center, 710 West 168th Street, New York, NY, 10032, USA
| | - Lara Petricca
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy.,IRBM Promidis, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy
| | - J Lawrence Marsh
- Department of Developmental and Cell Biology, University of California, Irvine, 92697, USA
| | - Silvia Gines
- Departamento de Ciencias Biomedicas, Facultat de Medicina, Instituto de Neurociencias, Universitat de Barcelona, Barcelona, Spain
| | - Iolanda Santimone
- Huntington and Rare Diseases Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Massimo Marano
- Huntington and Rare Diseases Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - 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
| | - Ferdinando Squitieri
- Huntington and Rare Diseases Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Andrea Caricasole
- IRBM Science Park, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy. .,IRBM Promidis, Via Pontina km 30.600, 00071, Pomezia, Rome, Italy.
| |
Collapse
|
20
|
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
|
21
|
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.
Collapse
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
| |
Collapse
|
22
|
Fodale V, Boggio R, Daldin M, Cariulo C, Spiezia MC, Byrne LM, Leavitt BR, Wild EJ, Macdonald D, Weiss A, Bresciani A. Validation of Ultrasensitive Mutant Huntingtin Detection in Human Cerebrospinal Fluid by Single Molecule Counting Immunoassay. J Huntingtons Dis 2017; 6:349-361. [PMID: 29125493 PMCID: PMC5757651 DOI: 10.3233/jhd-170269] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND The measurement of disease-relevant biomarkers has become a major component of clinical trial design, but in the absence of rigorous clinical and analytical validation of detection methodology, interpretation of results may be misleading. In Huntington's disease (HD), measurement of the concentration of mutant huntingtin protein (mHTT) in cerebrospinal fluid (CSF) of patients may serve as both a disease progression biomarker and a pharmacodynamic readout for HTT-lowering therapeutic approaches. We recently published the quantification of mHTT levels in HD patient CSF by a novel ultrasensitive immunoassay-based technology and here analytically validate it for use. OBJECTIVE This work aims to analytically and clinically validate our ultrasensitive assay for mHTT measurement in human HD CSF, for application as a pharmacodynamic biomarker of CNS mHTT lowering in clinical trials. METHODS The single molecule counting (SMC) assay is an ultrasensitive bead-based immunoassay where upon specific recognition, dye-labeled antibodies are excited by a confocal laser and emit fluorescent light as a readout. The detection of mHTT by this technology was clinically validated following established Food and Drug Administration and European Medicine Agency guidelines. RESULTS The SMC assay was demonstrated to be accurate, precise, specific, and reproducible. While no matrix influence was detected, a list of interfering substances was compiled as a guideline for proper collection and storage of patient CSF samples. In addition, a set of recommendations on result interpretation is provided. CONCLUSIONS This SMC assay is a robust and ultrasensitive method for the relative quantification of mHTT in human CSF.
Collapse
Affiliation(s)
- Valentina Fodale
- IRBM Science Park, Pomezia, Rome, Italy
- IRBM Promidis, Pomezia, Rome, Italy
| | | | | | | | | | - Lauren M. Byrne
- University College London (UCL) Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, UK
| | - Blair R. Leavitt
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Edward J. Wild
- University College London (UCL) Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, UK
| | | | | | | |
Collapse
|
23
|
Sahoo B, Arduini I, Drombosky KW, Kodali R, Sanders LH, Greenamyre JT, Wetzel R. Folding Landscape of Mutant Huntingtin Exon1: Diffusible Multimers, Oligomers and Fibrils, and No Detectable Monomer. PLoS One 2016; 11:e0155747. [PMID: 27271685 PMCID: PMC4894636 DOI: 10.1371/journal.pone.0155747] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 05/03/2016] [Indexed: 12/19/2022] Open
Abstract
Expansion of the polyglutamine (polyQ) track of the Huntingtin (HTT) protein above 36 is associated with a sharply enhanced risk of Huntington’s disease (HD). Although there is general agreement that HTT toxicity resides primarily in N-terminal fragments such as the HTT exon1 protein, there is no consensus on the nature of the physical states of HTT exon1 that are induced by polyQ expansion, nor on which of these states might be responsible for toxicity. One hypothesis is that polyQ expansion induces an alternative, toxic conformation in the HTT exon1 monomer. Alternative hypotheses posit that the toxic species is one of several possible aggregated states. Defining the nature of the toxic species is particularly challenging because of facile interconversion between physical states as well as challenges to identifying these states, especially in vivo. Here we describe the use of fluorescence correlation spectroscopy (FCS) to characterize the detailed time and repeat length dependent self-association of HTT exon1-like fragments both with chemically synthesized peptides in vitro and with cell-produced proteins in extracts and in living cells. We find that, in vitro, mutant HTT exon1 peptides engage in polyQ repeat length dependent dimer and tetramer formation, followed by time dependent formation of diffusible spherical and fibrillar oligomers and finally by larger, sedimentable amyloid fibrils. For expanded polyQ HTT exon1 expressed in PC12 cells, monomers are absent, with tetramers being the smallest molecular form detected, followed in the incubation time course by small, diffusible aggregates at 6–9 hours and larger, sedimentable aggregates that begin to build up at 12 hrs. In these cell cultures, significant nuclear DNA damage appears by 6 hours, followed at later times by caspase 3 induction, mitochondrial dysfunction, and cell death. Our data thus defines limits on the sizes and concentrations of different physical states of HTT exon1 along the reaction profile in the context of emerging cellular distress. The data provide some new candidates for the toxic species and some new reservations about more well-established candidates. Compared to other known markers of HTT toxicity, nuclear DNA damage appears to be a relatively early pathological event.
Collapse
Affiliation(s)
- Bankanidhi Sahoo
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
| | - Irene Arduini
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
| | - Kenneth W. Drombosky
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
| | - Ravindra Kodali
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
| | - Laurie H. Sanders
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
| | - J. Timothy Greenamyre
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
| | - Ronald Wetzel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, United States of America
- * E-mail:
| |
Collapse
|
24
|
Vijayvargia R, Epand R, Leitner A, Jung TY, Shin B, Jung R, Lloret A, Singh Atwal R, Lee H, Lee JM, Aebersold R, Hebert H, Song JJ, Seong IS. Huntingtin's spherical solenoid structure enables polyglutamine tract-dependent modulation of its structure and function. eLife 2016; 5:e11184. [PMID: 27003594 PMCID: PMC4846397 DOI: 10.7554/elife.11184] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Accepted: 03/13/2016] [Indexed: 11/14/2022] Open
Abstract
The polyglutamine expansion in huntingtin protein causes Huntington’s disease. Here, we investigated structural and biochemical properties of huntingtin and the effect of the polyglutamine expansion using various biophysical experiments including circular dichroism, single-particle electron microscopy and cross-linking mass spectrometry. Huntingtin is likely composed of five distinct domains and adopts a spherical α-helical solenoid where the amino-terminal and carboxyl-terminal regions fold to contain a circumscribed central cavity. Interestingly, we showed that the polyglutamine expansion increases α-helical properties of huntingtin and affects the intramolecular interactions among the domains. Our work delineates the structural characteristics of full-length huntingtin, which are affected by the polyglutamine expansion, and provides an elegant solution to the apparent conundrum of how the extreme amino-terminal polyglutamine tract confers a novel property on huntingtin, causing the disease. DOI:http://dx.doi.org/10.7554/eLife.11184.001 Huntington’s disease is an inherited disorder that occurs in adulthood and sometimes in children. It causes progressive damage to the brain and people with the condition develop memory loss, movement difficulties, confusion, and other symptoms of mental decline. Eventually, the disease leads to death. Mutations in the gene that encodes a protein called huntingtin cause Huntington’s disease. Individuals who inherit just one copy of the mutated gene develop the condition. No treatments currently exist that can slow or stop disease progression. Genetic and molecular studies are beginning to shed light on how mutations in the gene encoding huntingtin cause the disease. Normally, the protein has a section near its tail end made up of the amino acid glutamine repeated around 23 times. Mutations that increase the number of glutamines to more than 38 cause Huntington’s disease. The more extra glutamines there are in this region of the protein, the earlier in life the disease symptoms begin. But it was not clear how these extra glutamines near the tail of huntingtin affect the structure and behavior of a protein that is more than 3,000 amino acids long. Now, Vijayvargia et al. have revealed why the tail end of huntingtin is so important. Several biophysical methods were used to determine the three-dimensional structure of the huntingtin protein. These methods revealed that the protein folds up into a hollow sphere and that its tail end is able to interact with the entire length of the protein and physically touches its opposite end. To see this in more detail, Vijayvargia et al. used another experimental technique called crosslinking mass spectrometry to confirm which parts of the huntingtin protein are in close contact with each other. Together with the structural data, these experiments suggest that the stretch of glutamines is in the position to bring about subtle, but widespread, changes throughout the huntingtin protein. That is to say, that having more glutamines slightly changes the curve of the sphere and alters the way different parts of the protein interact. Together the new findings explain why mutations that alter the tail of huntingtin affect the rest of the protein. Further work will now aim to provide a more-detailed structure of the huntingtin protein and to investigate what other roles of huntingtin are affected by the increased number of glutamines in the protein’s tail. These insights may help scientists understand how the mutated protein causes brain decline. DOI:http://dx.doi.org/10.7554/eLife.11184.002
Collapse
Affiliation(s)
- Ravi Vijayvargia
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, United States.,Department of Neurology, Harvard Medical School, Boston, United States
| | - Raquel Epand
- Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Alexander Leitner
- Department of Biology, Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule Zürich, Zurich, Switzerland
| | - Tae-Yang Jung
- Department of Biological Sciences, Cancer Metastasis Control Center, KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.,Department of Biosciences and Nutrition, Karolinska Institute, Solna, Sweden.,School of Technology and Health, KTH Royal Institute of Technology, Novum, Sweden
| | - Baehyun Shin
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, United States.,Department of Neurology, Harvard Medical School, Boston, United States
| | - Roy Jung
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, United States.,Department of Neurology, Harvard Medical School, Boston, United States
| | - Alejandro Lloret
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, United States.,Department of Neurology, Harvard Medical School, Boston, United States
| | - Randy Singh Atwal
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, United States.,Department of Neurology, Harvard Medical School, Boston, United States
| | - Hyeongseok Lee
- Department of Biological Sciences, Cancer Metastasis Control Center, KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Jong-Min Lee
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, United States.,Department of Neurology, Harvard Medical School, Boston, United States
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule Zürich, Zurich, Switzerland.,Faculty of Science, University of Zurich, Zurich, Switzerland
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institute, Solna, Sweden.,School of Technology and Health, KTH Royal Institute of Technology, Novum, Sweden
| | - Ji-Joon Song
- Department of Biological Sciences, Cancer Metastasis Control Center, KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Ihn Sik Seong
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, United States.,Department of Neurology, Harvard Medical School, Boston, United States
| |
Collapse
|
25
|
|