1
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Tejwani L, Ravindra NG, Lee C, Cheng Y, Nguyen B, Luttik K, Ni L, Zhang S, Morrison LM, Gionco J, Xiang Y, Yoon J, Ro H, Haidery F, Grijalva RM, Bae E, Kim K, Martuscello RT, Orr HT, Zoghbi HY, McLoughlin HS, Ranum LPW, Shakkottai VG, Faust PL, Wang S, van Dijk D, Lim J. Longitudinal single-cell transcriptional dynamics throughout neurodegeneration in SCA1. Neuron 2024; 112:362-383.e15. [PMID: 38016472 PMCID: PMC10922326 DOI: 10.1016/j.neuron.2023.10.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 09/10/2023] [Accepted: 10/27/2023] [Indexed: 11/30/2023]
Abstract
Neurodegeneration is a protracted process involving progressive changes in myriad cell types that ultimately results in the death of vulnerable neuronal populations. To dissect how individual cell types within a heterogeneous tissue contribute to the pathogenesis and progression of a neurodegenerative disorder, we performed longitudinal single-nucleus RNA sequencing of mouse and human spinocerebellar ataxia type 1 (SCA1) cerebellar tissue, establishing continuous dynamic trajectories of each cell population. Importantly, we defined the precise transcriptional changes that precede loss of Purkinje cells and, for the first time, identified robust early transcriptional dysregulation in unipolar brush cells and oligodendroglia. Finally, we applied a deep learning method to predict disease state accurately and identified specific features that enable accurate distinction of wild-type and SCA1 cells. Together, this work reveals new roles for diverse cerebellar cell types in SCA1 and provides a generalizable analysis framework for studying neurodegeneration.
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Affiliation(s)
- Leon Tejwani
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA.
| | - Neal G Ravindra
- Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Computer Science, Yale University, New Haven, CT 06510, USA
| | - Changwoo Lee
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Yubao Cheng
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Billy Nguyen
- University of California, San Francisco School of Medicine, San Francisco, CA 94143, USA
| | - Kimberly Luttik
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Luhan Ni
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Shupei Zhang
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Logan M Morrison
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - John Gionco
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Yangfei Xiang
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA; Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06510, USA
| | | | - Hannah Ro
- Yale College, New Haven, CT 06510, USA
| | | | - Rosalie M Grijalva
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | | | - Kristen Kim
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Psychiatry, Yale School of Medicine, New Haven, CT 06510, USA
| | - Regina T Martuscello
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Harry T Orr
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Huda Y Zoghbi
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA; Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hayley S McLoughlin
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Laura P W Ranum
- Department of Molecular Genetics and Microbiology, Center for Neurogenetics, College of Medicine, Genetics Institute, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Vikram G Shakkottai
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Siyuan Wang
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA; Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA.
| | - David van Dijk
- Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Computer Science, Yale University, New Haven, CT 06510, USA.
| | - Janghoo Lim
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA; Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA; Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06510, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale School of Medicine, New Haven, CT 06510, USA; Wu Tsai Institute, Yale School of Medicine, New Haven, CT 06510, USA.
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2
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Wright SE, Todd PK. Native functions of short tandem repeats. eLife 2023; 12:e84043. [PMID: 36940239 PMCID: PMC10027321 DOI: 10.7554/elife.84043] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 03/08/2023] [Indexed: 03/21/2023] Open
Abstract
Over a third of the human genome is comprised of repetitive sequences, including more than a million short tandem repeats (STRs). While studies of the pathologic consequences of repeat expansions that cause syndromic human diseases are extensive, the potential native functions of STRs are often ignored. Here, we summarize a growing body of research into the normal biological functions for repetitive elements across the genome, with a particular focus on the roles of STRs in regulating gene expression. We propose reconceptualizing the pathogenic consequences of repeat expansions as aberrancies in normal gene regulation. From this altered viewpoint, we predict that future work will reveal broader roles for STRs in neuronal function and as risk alleles for more common human neurological diseases.
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Affiliation(s)
- Shannon E Wright
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- Neuroscience Graduate Program, University of Michigan–Ann ArborAnn ArborUnited States
- Department of Neuroscience, Picower InstituteCambridgeUnited States
| | - Peter K Todd
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- VA Ann Arbor Healthcare SystemAnn ArborUnited States
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3
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Johnson SL, Tsou WL, Prifti MV, Harris AL, Todi SV. A survey of protein interactions and posttranslational modifications that influence the polyglutamine diseases. Front Mol Neurosci 2022; 15:974167. [PMID: 36187346 PMCID: PMC9515312 DOI: 10.3389/fnmol.2022.974167] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/27/2022] [Indexed: 01/20/2023] Open
Abstract
The presence and aggregation of misfolded proteins has deleterious effects in the nervous system. Among the various diseases caused by misfolded proteins is the family of the polyglutamine (polyQ) disorders. This family comprises nine members, all stemming from the same mutation—the abnormal elongation of a polyQ repeat in nine different proteins—which causes protein misfolding and aggregation, cellular dysfunction and disease. While it is the same type of mutation that causes them, each disease is distinct: it is influenced by regions and domains that surround the polyQ repeat; by proteins with which they interact; and by posttranslational modifications they receive. Here, we overview the role of non-polyQ regions that control the pathogenicity of the expanded polyQ repeat. We begin by introducing each polyQ disease, the genes affected, and the symptoms experienced by patients. Subsequently, we provide a survey of protein-protein interactions and posttranslational modifications that regulate polyQ toxicity. We conclude by discussing shared processes and pathways that bring some of the polyQ diseases together and may serve as common therapeutic entry points for this family of incurable disorders.
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Affiliation(s)
- Sean L. Johnson
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
| | - Matthew V. Prifti
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
| | - Autumn L. Harris
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
- Maximizing Access to Research Careers (MARC) Program, Wayne State University, Detroit, MI, United States
| | - Sokol V. Todi
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
- Maximizing Access to Research Careers (MARC) Program, Wayne State University, Detroit, MI, United States
- Department of Neurology, Wayne State University, Detroit, MI, United States
- *Correspondence: Sokol V. Todi,
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4
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Chen JM, Chen SK, Jin PP, Sun SC. Identification of the ataxin-1 interaction network and its impact on spinocerebellar ataxia type 1. Hum Genomics 2022; 16:29. [PMID: 35906672 PMCID: PMC9335979 DOI: 10.1186/s40246-022-00404-0] [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] [Received: 02/06/2022] [Accepted: 07/22/2022] [Indexed: 12/03/2022] Open
Abstract
Background Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disease caused by a polyglutamine expansion in the ataxin-1 protein. The pathogenic mechanism resulting in SCA1 is still unclear. Protein–protein interactions affect the function and stability of ataxin-1. Methods Wild-type and mutant ataxin-1 were expressed in HEK-293T cells. The levels of expression were assessed using real-time polymerase chain reaction (PCR) and Western blots. Co-immunoprecipitation was done in HEK-293T cells expressing exogenous wild-type and mutant ataxin-1 using anti-Flag antibody following by tandem affinity purification in order to study protein–protein interactions. The candidate interacting proteins were validated by immunoprecipitation. Chromatin immunoprecipitation and high-throughput sequencing and RNA immunoprecipitation and high-throughput sequencing were performed using HEK-293T cells expressing wild-type or mutant ataxin-1. Results In this study using HEK-293T cells, we found that wild-type ataxin-1 interacted with MCM2, GNAS, and TMEM206, while mutant ataxin-1 lost its interaction with MCM2, GNAS, and TMEM206. Two ataxin-1 binding targets containing the core GGAG or AAAT were identified in HEK-293T cells using ChIP-seq. Gene Ontology analysis of the top ataxin-1 binding genes identified SLC6A15, NTF3, KCNC3, and DNAJC6 as functional genes in neurons in vitro. Ataxin-1 also was identified as an RNA-binding protein in HEK-293T cells using RIP-seq, but the polyglutamine expansion in the ataxin-1 had no direct effects on the RNA-binding activity of ataxin-1. Conclusions An expanded polyglutamine tract in ataxin-1 might interfere with protein–protein or protein–DNA interactions but had little effect on protein–RNA interactions. This study suggested that the dysfunction of protein–protein or protein–DNA interactions is involved in the pathogenesis of SCA1.
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Affiliation(s)
- Jiu-Ming Chen
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201801, China
| | - Shi-Kai Chen
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201801, China
| | - Pei-Pei Jin
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201801, China
| | - Shun-Chang Sun
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201801, China.
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5
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Huang H, Toker N, Burr E, Okoro J, Moog M, Hearing C, Lagalwar S. Intercellular Propagation and Aggregate Seeding of Mutant Ataxin-1. J Mol Neurosci 2021; 72:708-718. [PMID: 34826062 PMCID: PMC8986690 DOI: 10.1007/s12031-021-01944-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 11/06/2021] [Indexed: 01/07/2023]
Abstract
Intercellular propagation of aggregated protein inclusions along actin-based tunneling nanotubes (TNTs) has been reported as a means of pathogenic spread in Alzheimer’s, Parkinson’s, and Huntington’s diseases. Propagation of oligomeric-structured polyglutamine-expanded ataxin-1 (Atxn1[154Q]) has been reported in the cerebellum of a Spinocerebellar ataxia type 1 (SCA1) knock-in mouse to correlate with disease propagation. In this study, we investigated whether a physiologically relevant polyglutamine-expanded ATXN1 protein (ATXN1[82Q]) could propagate intercellularly. Using a cerebellar-derived live cell model, we observed ATXN1 aggregates form in the nucleus, subsequently form in the cytoplasm, and finally, propagate to neighboring cells along actin-based intercellular connections. Additionally, we observed the facilitation of aggregate-resistant proteins into aggregates given the presence of aggregation-prone proteins within cells. Taken together, our results support a pathogenic role of intercellular propagation of polyglutamine-expanded ATXN1 inclusions.
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Affiliation(s)
- Haoyang Huang
- Neuroscience Program, Skidmore College, Saratoga Springs, NY, USA
| | - Nicholas Toker
- Neuroscience Program, Skidmore College, Saratoga Springs, NY, USA
| | - Eliza Burr
- Neuroscience Program, Skidmore College, Saratoga Springs, NY, USA
| | - Jeff Okoro
- Neuroscience Program, Skidmore College, Saratoga Springs, NY, USA
| | - Maia Moog
- Neuroscience Program, Skidmore College, Saratoga Springs, NY, USA
| | - Casey Hearing
- Neuroscience Program, Skidmore College, Saratoga Springs, NY, USA
| | - Sarita Lagalwar
- Neuroscience Program, Skidmore College, Saratoga Springs, NY, USA.
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6
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Leysen S, Burnley RJ, Rodriguez E, Milroy LG, Soini L, Adamski CJ, Nitschke L, Davis R, Obsil T, Brunsveld L, Crabbe T, Zoghbi HY, Ottmann C, Davis JM. A Structural Study of the Cytoplasmic Chaperone Effect of 14-3-3 Proteins on Ataxin-1. J Mol Biol 2021; 433:167174. [PMID: 34302818 PMCID: PMC8505757 DOI: 10.1016/j.jmb.2021.167174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 12/20/2022]
Abstract
Expansion of the polyglutamine tract in the N terminus of Ataxin-1 is the main cause of the neurodegenerative disease, spinocerebellar ataxia type 1 (SCA1). However, the C-terminal part of the protein - including its AXH domain and a phosphorylation on residue serine 776 - also plays a crucial role in disease development. This phosphorylation event is known to be crucial for the interaction of Ataxin-1 with the 14-3-3 adaptor proteins and has been shown to indirectly contribute to Ataxin-1 stability. Here we show that 14-3-3 also has a direct anti-aggregation or "chaperone" effect on Ataxin-1. Furthermore, we provide structural and biophysical information revealing how phosphorylated S776 in the intrinsically disordered C terminus of Ataxin-1 mediates the cytoplasmic interaction with 14-3-3 proteins. Based on these findings, we propose that 14-3-3 exerts the observed chaperone effect by interfering with Ataxin-1 dimerization through its AXH domain, reducing further self-association. The chaperone effect is particularly important in the context of SCA1, as it was previously shown that a soluble form of mutant Ataxin-1 is the major driver of pathology.
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Affiliation(s)
- Seppe Leysen
- Global Chemistry, UCB Biopharma UK, Slough SL1 3WE, UK
| | | | | | - Lech-Gustav Milroy
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Technische Universiteit Eindhoven, Eindhoven 5600 MB, the Netherlands
| | - Lorenzo Soini
- Global Chemistry, UCB Biopharma UK, Slough SL1 3WE, UK; Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Technische Universiteit Eindhoven, Eindhoven 5600 MB, the Netherlands
| | - Carolyn J Adamski
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Larissa Nitschke
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rachel Davis
- Global Chemistry, UCB Biopharma UK, Slough SL1 3WE, UK
| | - Tomas Obsil
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague 12843, Czech Republic
| | - Lucas Brunsveld
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Technische Universiteit Eindhoven, Eindhoven 5600 MB, the Netherlands
| | - Tom Crabbe
- Immuno-Bone Discovery, UCB Biopharma UK, Slough SL1 3WE, UK
| | - Huda Yahya Zoghbi
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Christian Ottmann
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Technische Universiteit Eindhoven, Eindhoven 5600 MB, the Netherlands
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7
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Gkekas I, Gioran A, Boziki MK, Grigoriadis N, Chondrogianni N, Petrakis S. Oxidative Stress and Neurodegeneration: Interconnected Processes in PolyQ Diseases. Antioxidants (Basel) 2021; 10:antiox10091450. [PMID: 34573082 PMCID: PMC8471619 DOI: 10.3390/antiox10091450] [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: 07/14/2021] [Revised: 09/03/2021] [Accepted: 09/08/2021] [Indexed: 12/16/2022] Open
Abstract
Neurodegenerative polyglutamine (polyQ) disorders are caused by trinucleotide repeat expansions within the coding region of disease-causing genes. PolyQ-expanded proteins undergo conformational changes leading to the formation of protein inclusions which are associated with selective neuronal degeneration. Several lines of evidence indicate that these mutant proteins are associated with oxidative stress, proteasome impairment and microglia activation. These events may correlate with the induction of inflammation in the nervous system and disease progression. Here, we review the effect of polyQ-induced oxidative stress in cellular and animal models of polyQ diseases. Furthermore, we discuss the interplay between oxidative stress, neurodegeneration and neuroinflammation using as an example the well-known neuroinflammatory disease, Multiple Sclerosis. Finally, we review some of the pharmaceutical interventions which may delay the onset and progression of polyQ disorders by targeting disease-associated mechanisms.
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Affiliation(s)
- Ioannis Gkekas
- Institute of Applied Biosciences/Centre for Research and Technology Hellas, 57001 Thessaloniki, Greece;
| | - Anna Gioran
- Institute of Chemical Biology, National Hellenic Research Foundation, 11635 Athens, Greece; (A.G.); (N.C.)
| | - Marina Kleopatra Boziki
- 2nd Neurological Department, AHEPA University General Hospital, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (M.K.B.); (N.G.)
| | - Nikolaos Grigoriadis
- 2nd Neurological Department, AHEPA University General Hospital, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (M.K.B.); (N.G.)
| | - Niki Chondrogianni
- Institute of Chemical Biology, National Hellenic Research Foundation, 11635 Athens, Greece; (A.G.); (N.C.)
| | - Spyros Petrakis
- Institute of Applied Biosciences/Centre for Research and Technology Hellas, 57001 Thessaloniki, Greece;
- Correspondence: ; Tel.: +30-2311257525
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8
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Malik I, Kelley CP, Wang ET, Todd PK. Molecular mechanisms underlying nucleotide repeat expansion disorders. Nat Rev Mol Cell Biol 2021; 22:589-607. [PMID: 34140671 PMCID: PMC9612635 DOI: 10.1038/s41580-021-00382-6] [Citation(s) in RCA: 127] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2021] [Indexed: 02/05/2023]
Abstract
The human genome contains over one million short tandem repeats. Expansion of a subset of these repeat tracts underlies over fifty human disorders, including common genetic causes of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (C9orf72), polyglutamine-associated ataxias and Huntington disease, myotonic dystrophy, and intellectual disability disorders such as Fragile X syndrome. In this Review, we discuss the four major mechanisms by which expansion of short tandem repeats causes disease: loss of function through transcription repression, RNA-mediated gain of function through gelation and sequestration of RNA-binding proteins, gain of function of canonically translated repeat-harbouring proteins, and repeat-associated non-AUG translation of toxic repeat peptides. Somatic repeat instability amplifies these mechanisms and influences both disease age of onset and tissue specificity of pathogenic features. We focus on the crosstalk between these disease mechanisms, and argue that they often synergize to drive pathogenesis. We also discuss the emerging native functions of repeat elements and how their dynamics might contribute to disease at a larger scale than currently appreciated. Lastly, we propose that lynchpins tying these disease mechanisms and native functions together offer promising therapeutic targets with potential shared applications across this class of human disorders.
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Affiliation(s)
- Indranil Malik
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Chase P Kelley
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA
- Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA.
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
- VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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9
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Cendelin J, Cvetanovic M, Gandelman M, Hirai H, Orr HT, Pulst SM, Strupp M, Tichanek F, Tuma J, Manto M. Consensus Paper: Strengths and Weaknesses of Animal Models of Spinocerebellar Ataxias and Their Clinical Implications. THE CEREBELLUM 2021; 21:452-481. [PMID: 34378174 DOI: 10.1007/s12311-021-01311-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/21/2021] [Indexed: 01/02/2023]
Abstract
Spinocerebellar ataxias (SCAs) represent a large group of hereditary degenerative diseases of the nervous system, in particular the cerebellum, and other systems that manifest with a variety of progressive motor, cognitive, and behavioral deficits with the leading symptom of cerebellar ataxia. SCAs often lead to severe impairments of the patient's functioning, quality of life, and life expectancy. For SCAs, there are no proven effective pharmacotherapies that improve the symptoms or substantially delay disease progress, i.e., disease-modifying therapies. To study SCA pathogenesis and potential therapies, animal models have been widely used and are an essential part of pre-clinical research. They mainly include mice, but also other vertebrates and invertebrates. Each animal model has its strengths and weaknesses arising from model animal species, type of genetic manipulation, and similarity to human diseases. The types of murine and non-murine models of SCAs, their contribution to the investigation of SCA pathogenesis, pathological phenotype, and therapeutic approaches including their advantages and disadvantages are reviewed in this paper. There is a consensus among the panel of experts that (1) animal models represent valuable tools to improve our understanding of SCAs and discover and assess novel therapies for this group of neurological disorders characterized by diverse mechanisms and differential degenerative progressions, (2) thorough phenotypic assessment of individual animal models is required for studies addressing therapeutic approaches, (3) comparative studies are needed to bring pre-clinical research closer to clinical trials, and (4) mouse models complement cellular and invertebrate models which remain limited in terms of clinical translation for complex neurological disorders such as SCAs.
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Affiliation(s)
- Jan Cendelin
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic. .,Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.
| | - Marija Cvetanovic
- Department of Neuroscience, Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mandi Gandelman
- Department of Neurology, University of Utah, 175 North Medical Drive East, Salt Lake City, UT, 84132, USA
| | - Hirokazu Hirai
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, 3-39-22, Gunma, 371-8511, Japan.,Viral Vector Core, Gunma University Initiative for Advanced Research (GIAR), Gunma, 371-8511, Japan
| | - Harry T Orr
- Department of Laboratory Medicine and Pathology, Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, 175 North Medical Drive East, Salt Lake City, UT, 84132, USA
| | - Michael Strupp
- Department of Neurology and German Center for Vertigo and Balance Disorders, Hospital of the Ludwig-Maximilians University, Munich, Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany
| | - Filip Tichanek
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.,Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic
| | - Jan Tuma
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.,The Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7843, San Antonio, TX, 78229, USA
| | - Mario Manto
- Unité des Ataxies Cérébelleuses, Service de Neurologie, CHU-Charleroi, Charleroi, Belgium.,Service des Neurosciences, Université de Mons, UMons, Mons, Belgium
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10
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Nitschke L, Coffin SL, Xhako E, El-Najjar DB, Orengo JP, Alcala E, Dai Y, Wan YW, Liu Z, Orr HT, Zoghbi HY. Modulation of ATXN1 S776 phosphorylation reveals the importance of allele-specific targeting in SCA1. JCI Insight 2021; 6:144955. [PMID: 33554954 PMCID: PMC7934855 DOI: 10.1172/jci.insight.144955] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/23/2020] [Indexed: 11/20/2022] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is an adult-onset neurodegenerative disorder characterized by motor incoordination, mild cognitive decline, respiratory dysfunction, and early lethality. It is caused by the expansion of the polyglutamine (polyQ) tract in Ataxin-1 (ATXN1), which stabilizes the protein, leading to its toxic accumulation in neurons. Previously, we showed that serine 776 (S776) phosphorylation is critical for ATXN1 stability and contributes to its toxicity in cerebellar Purkinje cells. Still, the therapeutic potential of disrupting S776 phosphorylation on noncerebellar SCA1 phenotypes remains unstudied. Here, we report that abolishing S776 phosphorylation specifically on the polyQ-expanded ATXN1 of SCA1-knockin mice reduces ATXN1 throughout the brain and not only rescues the cerebellar motor incoordination but also improves respiratory function and extends survival while not affecting the hippocampal learning and memory deficits. As therapeutic approaches are likely to decrease S776 phosphorylation on polyQ-expanded and WT ATXN1, we further disrupted S776 phosphorylation on both alleles and observed an attenuated rescue, demonstrating a potential protective role of WT allele. This study not only highlights the role of S776 phosphorylation to regulate ATXN1 levels throughout the brain but also suggests distinct brain region–specific disease mechanisms and demonstrates the importance of developing allele-specific therapies for maximal benefits in SCA1.
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Affiliation(s)
- Larissa Nitschke
- Program in Integrative Molecular and Biomedical Sciences and.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA
| | - Stephanie L Coffin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA.,Program in Genetics and Genomics
| | - Eder Xhako
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA.,Program in Genetics and Genomics
| | - Dany B El-Najjar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA
| | - James P Orengo
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA.,Department of Neurology, and
| | - Elizabeth Alcala
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA
| | - Yanwan Dai
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Ying-Wooi Wan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA
| | - Zhandong Liu
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Harry T Orr
- Institute for Translational Neuroscience and Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Huda Y Zoghbi
- Program in Integrative Molecular and Biomedical Sciences and.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA.,Program in Genetics and Genomics.,Department of Neurology, and.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Howard Hughes Medical Institute, Houston, Texas, USA
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11
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Tejwani L, Lim J. Pathogenic mechanisms underlying spinocerebellar ataxia type 1. Cell Mol Life Sci 2020; 77:4015-4029. [PMID: 32306062 PMCID: PMC7541529 DOI: 10.1007/s00018-020-03520-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 03/06/2020] [Accepted: 04/06/2020] [Indexed: 02/06/2023]
Abstract
The family of hereditary cerebellar ataxias is a large group of disorders with heterogenous clinical manifestations and genetic etiologies. Among these, over 30 autosomal dominantly inherited subtypes have been identified, collectively referred to as the spinocerebellar ataxias (SCAs). Generally, the SCAs are characterized by a progressive gait impairment with classical cerebellar features, and in a subset of SCAs, accompanied by extra-cerebellar features. Beyond the common gait impairment and cerebellar atrophy, the wide range of additional clinical features observed across the SCAs is likely explained by the diverse set of mutated genes that encode proteins with seemingly disparate functional roles in nervous system biology. By synthesizing knowledge obtained from studies of the various SCAs over the past several decades, convergence onto a few key cellular changes, namely ion channel dysfunction and transcriptional dysregulation, has become apparent and may represent central mechanisms of cerebellar disease pathogenesis. This review will detail our current understanding of the molecular pathogenesis of the SCAs, focusing primarily on the first described autosomal dominant spinocerebellar ataxia, SCA1, as well as the emerging common core mechanisms across the various SCAs.
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Affiliation(s)
- Leon Tejwani
- Interdepartmental Neuroscience Program, Yale School of Medicine, 295 Congress Avenue, New Haven, CT, 06510, USA
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Janghoo Lim
- Interdepartmental Neuroscience Program, Yale School of Medicine, 295 Congress Avenue, New Haven, CT, 06510, USA.
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, 06510, USA.
- Department of Genetics, Yale School of Medicine, New Haven, CT, 06510, USA.
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale School of Medicine, New Haven, CT, 06510, USA.
- Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, 06510, USA.
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12
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Manek R, Nelson T, Tseng E, Rodriguez-Lebron E. 5'UTR-mediated regulation of Ataxin-1 expression. Neurobiol Dis 2019; 134:104564. [PMID: 31381977 DOI: 10.1016/j.nbd.2019.104564] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 07/05/2019] [Accepted: 08/01/2019] [Indexed: 12/27/2022] Open
Abstract
Expression of mutant Ataxin-1 with an abnormally expanded polyglutamine domain is necessary for the onset and progression of spinocerebellar ataxia type 1 (SCA1). Understanding how Ataxin-1 expression is regulated in the human brain could inspire novel molecular therapies for this fatal, dominantly inherited neurodegenerative disease. Previous studies have shown that the ATXN1 3'UTR plays a key role in regulating the Ataxin-1 cellular pool via diverse post-transcriptional mechanisms. Here we show that elements within the ATXN1 5'UTR also participate in the regulation of Ataxin-1 expression. PCR and PacBio sequencing analysis of cDNA obtained from control and SCA1 human brain samples revealed the presence of three major, alternatively spliced ATXN1 5'UTR variants. In cell-based assays, fusion of these variants upstream of an EGFP reporter construct revealed significant and differential impacts on total EGFP protein output, uncovering a type of genetic rheostat-like function of the ATXN1 5'UTR. We identified ribosomal scanning of upstream AUG codons and increased transcript instability as potential mechanisms of regulation. Importantly, transcript-based analyses revealed significant differences in the expression pattern of ATXN1 5'UTR variants between control and SCA1 cerebellum. Together, the data presented here shed light into a previously unknown role for the ATXN1 5'UTR in the regulation of Ataxin-1 and provide new opportunities for the development of SCA1 therapeutics.
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Affiliation(s)
- Rachna Manek
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA; Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32610, USA
| | - Tiffany Nelson
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA; Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32610, USA
| | | | - Edgardo Rodriguez-Lebron
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA; Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32610, USA.
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13
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Zhang S, Williamson NA, Bogoyevitch MA. Complementary proteomics strategies capture an ataxin-1 interactome in Neuro-2a cells. Sci Data 2018; 5:180262. [PMID: 30457570 PMCID: PMC6244183 DOI: 10.1038/sdata.2018.262] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 10/05/2018] [Indexed: 11/25/2022] Open
Abstract
Ataxin-1 mutation, arising from a polyglutamine (polyQ) tract expansion, is the underlying genetic cause of the late-onset neurodegenerative disease Spinocerebellar ataxia type 1 (SCA1). To identify protein partners of polyQ-ataxin-1 in neuronal cells under control or stress conditions, here we report our complementary proteomics strategies of proximity-dependent biotin identification (BioID) and affinity purification (via GFP-Trap pulldown) in Neuro-2a cells expressing epitope-tagged forms of ataxin-1[85Q]. These approaches allowed our enrichment of proximal proteins and interacting partners, respectively, with the subsequent protein identification performed by liquid chromatography-MS/MS. Background proteins, not dependent on the presence of the polyQ-ataxin-1 protein, were additionally defined by their endogenous biotinylation (for the BioID protocol) or by their non-specific interaction with GFP only (in the GFP-Trap protocol). All datasets were generated from biological replicates. Following the removal of the identified background proteins from the acquired protein lists, our experimental design has captured a comprehensive polyQ-ataxin-1 proximal and direct protein partners under normal and stress conditions. Data are available via ProteomeXchange, with identifier PXD010352.
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Affiliation(s)
- Sunyuan Zhang
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Nicholas A. Williamson
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Marie A. Bogoyevitch
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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14
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Wan L, Xu K, Chen Z, Tang B, Jiang H. Roles of Post-translational Modifications in Spinocerebellar Ataxias. Front Cell Neurosci 2018; 12:290. [PMID: 30283301 PMCID: PMC6156280 DOI: 10.3389/fncel.2018.00290] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 08/13/2018] [Indexed: 12/17/2022] Open
Abstract
Post-translational modifications (PTMs), including phosphorylation, acetylation, ubiquitination, SUMOylation, etc., of proteins can modulate protein properties such as intracellular distribution, activity, stability, aggregation, and interactions. Therefore, PTMs are vital regulatory mechanisms for multiple cellular processes. Spinocerebellar ataxias (SCAs) are hereditary, heterogeneous, neurodegenerative diseases for which the primary manifestation involves ataxia. Because the pathogenesis of most SCAs is correlated with mutant proteins directly or indirectly, the PTMs of disease-related proteins might functionally affect SCA development and represent potential therapeutic interventions. Here, we review multiple PTMs related to disease-causing proteins in SCAs pathogenesis and their effects. Furthermore, we discuss these PTMs as potential targets for treating SCAs and describe translational therapies targeting PTMs that have been published.
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Affiliation(s)
- Linlin Wan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Keqin Xu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Zhao Chen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
- Laboratory of Medical Genetics, Central South University, Changsha, China
- Parkinson’s Disease Center of Beijing Institute for Brain Disorders, Beijing, China
- Collaborative Innovation Center for Brain Science, Shanghai, China
- Collaborative Innovation Center for Genetics and Development, Shanghai, China
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
- Laboratory of Medical Genetics, Central South University, Changsha, China
- Department of Neurology, Xinjiang Medical University, Ürümqi, China
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15
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Bondar VV, Adamski CJ, Onur TS, Tan Q, Wang L, Diaz-Garcia J, Park J, Orr HT, Botas J, Zoghbi HY. PAK1 regulates ATXN1 levels providing an opportunity to modify its toxicity in spinocerebellar ataxia type 1. Hum Mol Genet 2018; 27:2863-2873. [PMID: 29860311 PMCID: PMC6077814 DOI: 10.1093/hmg/ddy200] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 04/23/2018] [Accepted: 05/22/2018] [Indexed: 11/14/2022] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is caused by the expansion of a trinucleotide repeat that encodes a polyglutamine tract in ataxin-1 (ATXN1). The expanded polyglutamine in ATXN1 increases the protein's stability and results in its accumulation and toxicity. Previous studies have demonstrated that decreasing ATXN1 levels ameliorates SCA1 phenotypes and pathology in mouse models. We rationalized that reducing ATXN1 levels through pharmacological inhibition of its modulators could provide a therapeutic avenue for SCA1. Here, through a forward genetic screen in Drosophila we identified, p21-activated kinase 3 (Pak3) as a modulator of ATXN1 levels. Loss-of-function of fly Pak3 or Pak1, whose mammalian homologs belong to Group I of PAK proteins, reduces ATXN1 levels, and accordingly, improves disease pathology in a Drosophila model of SCA1. Knockdown of PAK1 potently reduces ATXN1 levels in mammalian cells independent of the well-characterized S776 phosphorylation site (known to stabilize ATXN1) thus revealing a novel molecular pathway that regulates ATXN1 levels. Furthermore, pharmacological inhibition of PAKs decreases ATXN1 levels in a mouse model of SCA1. To explore the potential of using PAK inhibitors in combination therapy, we combined the pharmacological inhibition of PAK with MSK1, a previously identified modulator of ATXN1, and examined their effects on ATXN1 levels. We found that inhibition of both pathways results in an additive decrease in ATXN1 levels. Together, this study identifies PAK signaling as a distinct molecular pathway that regulates ATXN1 levels and presents a promising opportunity to pursue for developing potential therapeutics for SCA1.
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Affiliation(s)
- Vitaliy V Bondar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Carolyn J Adamski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA
| | - Tarik S Onur
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Qiumin Tan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Li Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Javier Diaz-Garcia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Jeehye Park
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Harry T Orr
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
| | - Huda Y Zoghbi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
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16
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Lieberman AP, Shakkottai VG, Albin RL. Polyglutamine Repeats in Neurodegenerative Diseases. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2018; 14:1-27. [PMID: 30089230 DOI: 10.1146/annurev-pathmechdis-012418-012857] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Among the age-dependent protein aggregation disorders, nine neurodegenerative diseases are caused by expansions of CAG repeats encoding polyglutamine (polyQ) tracts. We review the clinical, pathological, and biological features of these inherited disorders. We discuss insights into pathogenesis gleaned from studies of model systems and patients, highlighting work that informs efforts to develop effective therapies. An important conclusion from these analyses is that expanded CAG/polyQ domains are the primary drivers of neurodegeneration, with the biology of carrier proteins influencing disease-specific manifestations. Additionally, it has become apparent that CAG/polyQ repeat expansions produce neurodegeneration via multiple downstream mechanisms, involving both gain- and loss-of-function effects. This conclusion indicates that the likelihood of developing effective therapies targeting single nodes is reduced. The evaluation of treatments for premanifest disease will likely require new investigational approaches. We highlight the opportunities and challenges underlying ongoing work and provide recommendations related to the development of symptomatic and disease-modifying therapies and biomarkers that could inform future research.
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Affiliation(s)
- Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA;
| | - Vikram G Shakkottai
- Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA; , .,Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Roger L Albin
- Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA; , .,Neurology Service and the Geriatric Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare System, Ann Arbor, Michigan 48105, USA
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17
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Chen C, Fang X, Sun S. Diagnosis of polyglutamine spinocerebellar ataxias by polymerase chain reaction amplification and Sanger sequencing. Mol Med Rep 2018; 18:1037-1042. [PMID: 29845242 DOI: 10.3892/mmr.2018.9043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 05/09/2018] [Indexed: 11/06/2022] Open
Abstract
Spinocerebellar ataxia (SCA) is a group of genetic diseases of the nervous system with genetic and clinical heterogeneity. SCA is often caused by an expanded CAG repeat sequence in the encoding protein. Genetic testing is necessary to diagnose and classify the types of SCA. Next‑generation DNA sequencing usually generates a high error rate for insertion or deletion mutations, so it is unhelpful for classifying the types of SCA. In the present study, a Chinese SCA pedigree was preliminarily diagnosed with SCA1 using polymerase chain reaction (PCR) amplification. The propositus and his three younger siblings were diagnosed with SCA1 as a result of the identification of the length of the expanded CAG repeat sequence in the ATXN1 gene performed using Sanger sequencing. The current study presents a convenient and efficient method to identify causative mutations for polyglutamine SCA using PCR amplification followed by Sanger sequencing.
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Affiliation(s)
- Changqiang Chen
- Department of Laboratory Medicine, Ruijin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai 201801, P.R. China
| | - Xuqian Fang
- Department of Laboratory Medicine, Ruijin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai 201801, P.R. China
| | - Shunchang Sun
- Department of Laboratory Medicine, Ruijin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai 201801, P.R. China
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18
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Pérez Ortiz JM, Mollema N, Toker N, Adamski CJ, O'Callaghan B, Duvick L, Friedrich J, Walters MA, Strasser J, Hawkinson JE, Zoghbi HY, Henzler C, Orr HT, Lagalwar S. Reduction of protein kinase A-mediated phosphorylation of ATXN1-S776 in Purkinje cells delays onset of Ataxia in a SCA1 mouse model. Neurobiol Dis 2018; 116:93-105. [PMID: 29758256 DOI: 10.1016/j.nbd.2018.05.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/17/2018] [Accepted: 05/09/2018] [Indexed: 12/27/2022] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a polyglutamine (polyQ) repeat neurodegenerative disease in which a primary site of pathogenesis are cerebellar Purkinje cells. In addition to polyQ expansion of ataxin-1 protein (ATXN1), phosphorylation of ATXN1 at the serine 776 residue (ATXN1-pS776) plays a significant role in protein toxicity. Utilizing a biochemical approach, pharmacological agents and cell-based assays, including SCA1 patient iPSC-derived neurons, we examine the role of Protein Kinase A (PKA) as an effector of ATXN1-S776 phosphorylation. We further examine the implications of PKA-mediated phosphorylation at ATXN1-S776 on SCA1 through genetic manipulation of the PKA catalytic subunit Cα in Pcp2-ATXN1[82Q] mice. Here we show that pharmacologic inhibition of S776 phosphorylation in transfected cells and SCA1 patient iPSC-derived neuronal cells lead to a decrease in ATXN1. In vivo, reduction of PKA-mediated ATXN1-pS776 results in enhanced degradation of ATXN1 and improved cerebellar-dependent motor performance. These results provide evidence that PKA is a biologically important kinase for ATXN1-pS776 in cerebellar Purkinje cells.
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Affiliation(s)
- Judit M Pérez Ortiz
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Nissa Mollema
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Nicholas Toker
- Skidmore College Neuroscience Program, Saratoga Springs, NY, United States
| | - Carolyn J Adamski
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, and Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, United States
| | - Brennon O'Callaghan
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Lisa Duvick
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Jillian Friedrich
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Michael A Walters
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, United States
| | - Jessica Strasser
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, United States
| | - Jon E Hawkinson
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, United States
| | - Huda Y Zoghbi
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, and Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, United States
| | - Christine Henzler
- RISS Bioinformatics, Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN, United States
| | - Harry T Orr
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States.
| | - Sarita Lagalwar
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States; Skidmore College Neuroscience Program, Saratoga Springs, NY, United States.
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19
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Liu J, Su B. Integrated analysis supports ATXN1 as a schizophrenia risk gene. Schizophr Res 2018; 195:298-305. [PMID: 29055568 DOI: 10.1016/j.schres.2017.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 07/27/2017] [Accepted: 10/08/2017] [Indexed: 12/13/2022]
Abstract
Protein-protein interaction (PPI) is informative in identifying hidden disease risk genes that tend to interact with known risk genes usually working together in the same disease module. With the use of an integrated approach combining PPI information with pathway and expression analysis as well as genome-wide association study (GWAS), we intended to find new risk genes for schizophrenia (SCZ). We showed that ATXN1 was the only direct PPI partner of the know SCZ risk gene ZNF804A, and it also had direct PPIs with other 18 known SCZ risk genes. ATXN1 serves as one of the hub genes in the PPI network containing many known SCZ risk genes, and this network is significantly enriched for the MAPK signaling pathway. Further gene expression analysis indicated that ATXN1 is highly expressed in prefrontal cortex, and SCZ patients had significantly decreased expression compared with healthy controls. Finally, the published GWAS data supports an association of ATXN1 with SCZ as well as other psychiatric disorders though not reaching genome-wide significance. These convergent evidences support ATXN1 as a promising risk gene for SCZ, and the integrated approach serves as a useful tool for dissecting the genetic basis of psychiatric disorders.
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Affiliation(s)
- Jiewei Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China; Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China
| | - Bing Su
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China.
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20
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Pérez Ortiz JM, Orr HT. Spinocerebellar Ataxia Type 1: Molecular Mechanisms of Neurodegeneration and Preclinical Studies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1049:135-145. [PMID: 29427101 DOI: 10.1007/978-3-319-71779-1_6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Spinocerebellar ataxia type 1 (SCA1) is an adult-onset, inherited disease that leads to degeneration of Purkinje cells of the cerebellum and culminates in death 10-30 years after disease onset. SCA1 is caused by a CAG repeat mutation in the ATXN1 gene, encoding the ATXN1 protein with an abnormally expanded polyglutamine tract. As neurodegeneration progresses, other brain regions become involved and contribute to cognitive deficits as well as problems with speech, swallowing, and control of breathing. The fundamental basis of pathology is an aberration in the normal function of Purkinje cells affecting regulation of gene transcription and RNA splicing. Glutamine-expanded ATXN1 is highly stable and more resistant to degradation. Moreover, phosphorylation at S776 in ATXN1 is a post-translational modification known to influence protein levels. SCA1 remains an untreatable disease managed only by palliative care. Preclinical studies are founded on the principle that mutant protein load is toxic and attenuating ATXN1 protein levels can alleviate disease. Two approaches being pursued are targeting gene expression or protein levels. Viral delivery of miRNAs harnesses the RNAi pathway to destroy ATXN1 mRNA. This approach shows promise in mouse models of disease. At the protein level, kinase inhibitors that block ATXN1-S776 phosphorylation may lead to therapeutic clearance of unphosphorylated ATXN1.
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Affiliation(s)
- Judit M Pérez Ortiz
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA.,Medical Scientist Training Program, University of Minnesota, Minneapolis, MN, 55455, USA.,Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Harry T Orr
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA. .,Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, 55455, USA.
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The CAG-polyglutamine repeat diseases: a clinical, molecular, genetic, and pathophysiologic nosology. HANDBOOK OF CLINICAL NEUROLOGY 2018; 147:143-170. [PMID: 29325609 DOI: 10.1016/b978-0-444-63233-3.00011-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Throughout the genome, unstable tandem nucleotide repeats can expand to cause a variety of neurologic disorders. Expansion of a CAG triplet repeat within a coding exon gives rise to an elongated polyglutamine (polyQ) tract in the resultant protein product, and accounts for a unique category of neurodegenerative disorders, known as the CAG-polyglutamine repeat diseases. The nine members of the CAG-polyglutamine disease family include spinal and bulbar muscular atrophy (SBMA), Huntington disease, dentatorubral pallidoluysian atrophy, and six spinocerebellar ataxias (SCA 1, 2, 3, 6, 7, and 17). All CAG-polyglutamine diseases are dominantly inherited, with the exception of SBMA, which is X-linked, and many CAG-polyglutamine diseases display anticipation, which is defined as increasing disease severity in successive generations of an affected kindred. Despite widespread expression of the different polyQ-expanded disease proteins throughout the body, each CAG-polyglutamine disease strikes a particular subset of neurons, although the mechanism for this cell-type selectivity remains poorly understood. While the different genes implicated in these disorders display amino acid homology only in the repeat tract domain, certain pathologic molecular processes have been implicated in almost all of the CAG-polyglutamine repeat diseases, including protein aggregation, proteolytic cleavage, transcription dysregulation, autophagy impairment, and mitochondrial dysfunction. Here we highlight the clinical and molecular genetic features of each distinct disorder, and then discuss common themes in CAG-polyglutamine disease pathogenesis, closing with emerging advances in therapy development.
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Short-term succinic acid treatment mitigates cerebellar mitochondrial OXPHOS dysfunction, neurodegeneration and ataxia in a Purkinje-specific spinocerebellar ataxia type 1 (SCA1) mouse model. PLoS One 2017; 12:e0188425. [PMID: 29211771 PMCID: PMC5718515 DOI: 10.1371/journal.pone.0188425] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 11/07/2017] [Indexed: 11/19/2022] Open
Abstract
Mitochondrial dysfunction plays a significant role in neurodegenerative disease including ataxias and other movement disorders, particularly those marked by progressive degeneration in the cerebellum. In this study, we investigate the role of mitochondrial oxidative phosphorylation (OXPHOS) deficits in cerebellar tissue of a Purkinje cell-driven spinocerebellar ataxia type 1 (SCA1) mouse. Using RNA sequencing transcriptomics, OXPHOS complex assembly analysis and oxygen consumption assays, we report that in the presence of mutant polyglutamine-expanded ataxin-1, SCA1 mice display deficits in cerebellar OXPHOS complex I (NADH-coenzyme Q oxidoreductase). Complex I genes are upregulated at the time of symptom onset and upregulation persists into late stage disease; yet, functional assembly of complex I macromolecules are diminished and oxygen respiration through complex I is reduced. Acute treatment of postsymptomatic SCA1 mice with succinic acid, a complex II (succinate dehydrogenase) electron donor to bypass complex I dysfunction, ameliorated cerebellar OXPHOS dysfunction, reduced cerebellar pathology and improved motor behavior. Thus, exploration of mitochondrial dysfunction and its role in neurodegenerative ataxias, and warrants further investigation.
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Kacirova M, Novacek J, Man P, Obsilova V, Obsil T. Structural Basis for the 14-3-3 Protein-Dependent Inhibition of Phosducin Function. Biophys J 2017; 112:1339-1349. [PMID: 28402877 DOI: 10.1016/j.bpj.2017.02.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 02/21/2017] [Accepted: 02/28/2017] [Indexed: 01/06/2023] Open
Abstract
Phosducin (Pdc) is a conserved phosphoprotein that, when unphosphorylated, binds with high affinity to the complex of βγ-subunits of G protein transducin (Gtβγ). The ability of Pdc to bind to Gtβγ is inhibited through its phosphorylation at S54 and S73 within the N-terminal domain (Pdc-ND) followed by association with the scaffolding protein 14-3-3. However, the molecular basis for the 14-3-3-dependent inhibition of Pdc binding to Gtβγ is unclear. By using small-angle x-ray scattering, high-resolution NMR spectroscopy, and limited proteolysis coupled with mass spectrometry, we show that phosphorylated Pdc and 14-3-3 form a complex in which the Pdc-ND region 45-80, which forms a part of Pdc's Gtβγ binding surface and contains both phosphorylation sites, is restrained within the central channel of the 14-3-3 dimer, with both 14-3-3 binding motifs simultaneously participating in protein association. The N-terminal part of Pdc-ND is likely located outside the central channel of the 14-3-3 dimer, but Pdc residues 20-30, which are also involved in Gtβγ binding, are positioned close to the surface of the 14-3-3 dimer. The C-terminal domain of Pdc is located outside the central channel and its structure is unaffected by the complex formation. These results indicate that the 14-3-3 protein-mediated inhibition of Pdc binding to Gtβγ is based on steric occlusion of Pdc's Gtβγ binding surface.
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Affiliation(s)
- Miroslava Kacirova
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic; Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Novacek
- CEITEC, Masaryk University, Brno, Czech Republic
| | - Petr Man
- BioCeV-Institute of Microbiology, Czech Academy of Sciences, Vestec, Czech Republic; Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Veronika Obsilova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
| | - Tomas Obsil
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic; Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
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Eisenreichova A, Klima M, Boura E. Crystal structures of a yeast 14-3-3 protein from Lachancea thermotolerans in the unliganded form and bound to a human lipid kinase PI4KB-derived peptide reveal high evolutionary conservation. Acta Crystallogr F Struct Biol Commun 2016; 72:799-803. [PMID: 27827352 PMCID: PMC5101580 DOI: 10.1107/s2053230x16015053] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 09/22/2016] [Indexed: 01/02/2023] Open
Abstract
14-3-3 proteins bind phosphorylated binding partners to regulate several of their properties, including enzymatic activity, stability and subcellular localization. Here, two crystal structures are presented: the crystal structures of the 14-3-3 protein (also known as Bmh1) from the yeast Lachancea thermotolerans in the unliganded form and bound to a phosphopeptide derived from human PI4KB (phosphatidylinositol 4-kinase B). The structures demonstrate the high evolutionary conservation of ligand recognition by 14-3-3 proteins. The structural analysis suggests that ligand recognition by 14-3-3 proteins evolved very early in the evolution of eukaryotes and remained conserved, underlying the importance of 14-3-3 proteins in physiology.
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Affiliation(s)
- Andrea Eisenreichova
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nam. 2, 166 10 Prague 6, Czech Republic
| | - Martin Klima
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nam. 2, 166 10 Prague 6, Czech Republic
| | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nam. 2, 166 10 Prague 6, Czech Republic
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Sánchez I, Balagué E, Matilla-Dueñas A. Ataxin-1 regulates the cerebellar bioenergetics proteome through the GSK3β-mTOR pathway which is altered in Spinocerebellar ataxia type 1 (SCA1). Hum Mol Genet 2016; 25:4021-4040. [PMID: 27466200 DOI: 10.1093/hmg/ddw242] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 06/21/2016] [Accepted: 07/11/2016] [Indexed: 12/17/2022] Open
Abstract
A polyglutamine expansion within the ataxin-1 protein (ATXN1) underlies spinocerebellar ataxia type-1 (SCA1), a neurological disorder mainly characterized by ataxia and cerebellar deficits. In SCA1, both loss and gain of ATXN1 biological functions contribute to cerebellar pathogenesis. However, the critical ATXN1 functions and pathways involved remain unclear. To further investigate the early signalling pathways regulated by ATXN1, we performed an unbiased proteomic study of the Atxn1-KO 5-week-old mice cerebellum. Here, we show that lack of ATXN1 expression induces early alterations in proteins involved in glycolysis [pyruvate kinase, muscle, isoform 1 protein (PKM-i1), citrate synthase (CS), glycerol-3-phosphate dehydrogenase 2 (GPD2), glucose-6-phosphate isomerase (GPI), alpha -: enolase (ENO1)], ATP synthesis [CS, Succinate dehydrogenase complex,subunit A (SDHA), ATP synthase subunit d, mitochondrial (ATP5H)] and oxidative stress [peroxiredoxin-6 (PRDX6), aldehyde dehydrogenase family 1, subfamily A1, 10-formyltetrahydrofolate dehydrogenase]. In the SCA1 mice, several of these proteins (PKM-i1, ATP5H, PRDX6, proteome subunit A6) were down-regulated and ATP levels decreased. The underlying mechanism does not involve modulation of mitochondrial biogenesis, but dysregulation of the activity of the metabolic regulators glycogen synthase kinase 3B (GSK3β), decreased in Atxn1-KO and increased in SCA1 mice, and mechanistic target of rapamycin (serine/threonine kinase) (mTOR), unchanged in the Atxn1-KO and decreased in SCA1 mice cerebellum before the onset of ataxic symptoms. Pharmacological inhibition of GSK3β and activation of mTOR in a SCA1 cell model ameliorated identified ATXN1-regulated metabolic proteome and ATP alterations. Taken together, these results point to an early role of ATXN1 in the regulation of bioenergetics homeostasis in the mouse cerebellum. Moreover, data suggest GSK3β and mTOR pathways modulate this ATXN1 function in SCA1 pathogenesis that could be targeted therapeutically prior to the onset of disease symptoms in SCA1 and other pathologies involving dysregulation of ATXN1 functions.
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Affiliation(s)
- Ivelisse Sánchez
- Functional and Translational Neurogenetics Unit, Department of Neurosciences, Health Sciences Research Institute Germans Trias i Pujol (IGTP)-Universitat Autonoma de Barcelona, Crta. de Can Ruti, camí de les escoles s/n, 08916 Badalona, Barcelona, Spain
| | - Eudald Balagué
- Functional and Translational Neurogenetics Unit, Department of Neurosciences, Health Sciences Research Institute Germans Trias i Pujol (IGTP)-Universitat Autonoma de Barcelona, Crta. de Can Ruti, camí de les escoles s/n, 08916 Badalona, Barcelona, Spain
| | - Antoni Matilla-Dueñas
- Functional and Translational Neurogenetics Unit, Department of Neurosciences, Health Sciences Research Institute Germans Trias i Pujol (IGTP)-Universitat Autonoma de Barcelona, Crta. de Can Ruti, camí de les escoles s/n, 08916 Badalona, Barcelona, Spain
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Kohiyama MF, Lagalwar S. Stabilization and Degradation Mechanisms of Cytoplasmic Ataxin-1. J Exp Neurosci 2016; 9:123-9. [PMID: 27168726 PMCID: PMC4859447 DOI: 10.4137/jen.s25469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 12/24/2022] Open
Abstract
Aggregation-prone proteins in neurodegenerative disease disrupt cellular protein stabilization and degradation pathways. The neurodegenerative disease spinocerebellar ataxia type 1 (SCA1) is caused by a coding polyglutamine expansion in the Ataxin-1 gene (ATXN1), which gives rise to the aggregation-prone mutant form of ATXN1 protein. Cerebellar Purkinje neurons, preferentially vulnerable in SCA1, produce ATXN1 protein in both cytoplasmic and nuclear compartments. Cytoplasmic stabilization of ATXN1 by phosphorylation and 14-3-3-mediated mechanisms ultimately drive translocation of the protein to the nucleus where aggregation may occur. However, experimental inhibition of phosphorylation and 14-3-3 binding results in rapid degradation of ATXN1, thus preventing nuclear translocation and cellular toxicity. The exact mechanism of cytoplasmic ATXN1 degradation is currently unknown; further investigation of degradation may provide future therapeutic targets. This review examines the present understanding of cytoplasmic ATXN1 stabilization and potential degradation mechanisms during normal and pathogenic states.
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Affiliation(s)
- Mayumi F Kohiyama
- B.A., Skidmore College Neuroscience Program, Saratoga Springs, NY, USA
| | - Sarita Lagalwar
- Assistant Professor of Neuroscience, Williamson Chair in Neuroscience, Skidmore College Neuroscience Program, Saratoga Springs, NY, USA
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Keiser MS, Kordower JH, Gonzalez-Alegre P, Davidson BL. Broad distribution of ataxin 1 silencing in rhesus cerebella for spinocerebellar ataxia type 1 therapy. Brain 2015; 138:3555-66. [PMID: 26490326 DOI: 10.1093/brain/awv292] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/21/2015] [Indexed: 11/13/2022] Open
Abstract
Spinocerebellar ataxia type 1 is one of nine polyglutamine expansion diseases and is characterized by cerebellar ataxia and neuronal degeneration in the cerebellum and brainstem. Currently, there are no effective therapies for this disease. Previously, we have shown that RNA interference mediated silencing of ATXN1 mRNA provides therapeutic benefit in mouse models of the disease. Adeno-associated viral delivery of an engineered microRNA targeting ATXN1 to the cerebella of well-established mouse models improved motor phenotypes, neuropathy, and transcriptional changes. Here, we test the translatability of this approach in adult rhesus cerebella. Nine adult male and three adult female rhesus macaque were unilaterally injected with our therapeutic vector, a recombinant adeno-associated virus type 1 (rAAV1) expressing our RNAi trigger (miS1) and co-expressing enhanced green fluorescent protein (rAAV1.miS1eGFP) into the deep cerebellar nuclei using magnetic resonance imaging guided techniques combined with a Stealth Navigation system (Medtronics Inc.). Transduction was evident in the deep cerebellar nuclei, cerebellar Purkinje cells, the brainstem and the ventral lateral thalamus. Reduction of endogenous ATXN1 messenger RNA levels were ≥30% in the deep cerebellar nuclei, the cerebellar cortex, inferior olive, and thalamus relative to the uninjected hemisphere. There were no clinical complications, and quantitative and qualitative analyses suggest that this therapeutic intervention strategy and subsequent reduction of ATXN1 is well tolerated. Collectively the data illustrate the biodistribution and tolerability of rAAV1.miS1eGFP administration to the adult rhesus cerebellum and are supportive of clinical application for spinocerebellar ataxia type 1.
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Affiliation(s)
- Megan S Keiser
- 1 The Raymond G Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Jeffrey H Kordower
- 2 Department of Neurological Sciences, Rush University, Chicago, IL, USA
| | | | - Beverly L Davidson
- 4 The Raymond G Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, and the Department of Pathology and Laboratory Medicine, the University of Pennsylvania, Philadelphia, PA, USA
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Chua JP, Reddy SL, Yu Z, Giorgetti E, Montie HL, Mukherjee S, Higgins J, McEachin RC, Robins DM, Merry DE, Iñiguez-Lluhí JA, Lieberman AP. Disrupting SUMOylation enhances transcriptional function and ameliorates polyglutamine androgen receptor-mediated disease. J Clin Invest 2015; 125:831-45. [PMID: 25607844 DOI: 10.1172/jci73214] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 11/25/2014] [Indexed: 12/20/2022] Open
Abstract
Expansion of the polyglutamine (polyQ) tract within the androgen receptor (AR) causes neuromuscular degeneration in individuals with spinobulbar muscular atrophy (SBMA). PolyQ AR has diminished transcriptional function and exhibits ligand-dependent proteotoxicity, features that have both been implicated in SBMA; however, the extent to which altered AR transcriptional function contributes to pathogenesis remains controversial. Here, we sought to dissociate effects of diminished AR function from polyQ-mediated proteotoxicity by enhancing the transcriptional activity of polyQ AR. To accomplish this, we bypassed the inhibitory effect of AR SUMOylation (where SUMO indicates small ubiquitin-like modifier) by mutating conserved lysines in the polyQ AR that are sites of SUMOylation. We determined that replacement of these residues by arginine enhances polyQ AR activity as a hormone-dependent transcriptional regulator. In a murine model, disruption of polyQ AR SUMOylation rescued exercise endurance and type I muscle fiber atrophy; it also prolonged survival. These changes occurred without overt alterations in polyQ AR expression or aggregation, revealing the favorable trophic support exerted by the ligand-activated receptor. Our findings demonstrate beneficial effects of enhancing the transcriptional function of the ligand-activated polyQ AR and indicate that the SUMOylation pathway may be a potential target for therapeutic intervention in SBMA.
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Animal Models of Spinocerebellar Ataxia Type 1. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00063-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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From pathways to targets: understanding the mechanisms behind polyglutamine disease. BIOMED RESEARCH INTERNATIONAL 2014; 2014:701758. [PMID: 25309920 PMCID: PMC4189765 DOI: 10.1155/2014/701758] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 09/03/2014] [Indexed: 12/27/2022]
Abstract
The history of polyglutamine diseases dates back approximately 20 years to the discovery of a polyglutamine repeat in the androgen receptor of SBMA followed by the identification of similar expansion mutations in Huntington's disease, SCA1, DRPLA, and the other spinocerebellar ataxias. This common molecular feature of polyglutamine diseases suggests shared mechanisms in disease pathology and neurodegeneration of disease specific brain regions. In this review, we discuss the main pathogenic pathways including proteolytic processing, nuclear shuttling and aggregation, mitochondrial dysfunction, and clearance of misfolded polyglutamine proteins and point out possible targets for treatment.
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Yamada S, Marutsuka M, Inoue M, Zhang J, Abe SI, Ishibashi KI, Yamaguchi N, Eto K. The interaction of the ErbB4 intracellular domain p80 with α-enolase in the nuclei is associated with the inhibition of the neuregulin1-dependent cell proliferation. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 5:21-29. [PMID: 24955285 PMCID: PMC4058961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/16/2014] [Indexed: 06/03/2023]
Abstract
We have shown that the receptor tyrosine kinase ErbB4 signals neuregulin1-stimulated proliferation of human cells. Some isoforms of ErbB4 are cleaved to release the soluble intracellular domain p80; however, the function of p80 in cell proliferation remained unclear. Here we propose the possibility for p80 as a negative feedback modulator of ErbB4-mediated cell proliferation. Cells exposed to lower doses of neuregulin1 displayed a stimulated proliferation and contained ErbB4 but barely p80. By contrast, cells exposed to its higher doses displayed a suppressed proliferation and contained p80 but barely ErbB4. Analyses with cells overexpressing the p80 wild type and mutants indicated that nuclear p80 inhibits cell proliferation independently of the tyrosine kinase activity. A screen for a novel protein that interacts with p80 identified α-enolase, which is reported as a transcriptional inhibitor for the proliferation-associated c-myc gene. The c-myc mRNA expression was induced by lower doses of neuregulin1 but was suppressed by its higher doses. Subcellular fractionation demonstrated the localization of not only p80 and α-enolase but also the decrease of the functional c-myc amount in the nuclei of cells exposed to higher doses of neuregulin1. These results suggested that p80, which is generated from ErbB4 and translocates to the nuclei, interacts with α-enolase and inhibits neuregulin1-dependent ErbB4-mediated cell proliferation by impairing the c-myc gene transcription.
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Affiliation(s)
- Satomi Yamada
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Masaki Marutsuka
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Miyabi Inoue
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Jidong Zhang
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Shin-ichi Abe
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Ken-ichi Ishibashi
- Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Naoto Yamaguchi
- Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Ko Eto
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
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Beyond the glutamine expansion: influence of posttranslational modifications of ataxin-1 in the pathogenesis of spinocerebellar ataxia type 1. Mol Neurobiol 2014; 50:866-874. [PMID: 24752589 DOI: 10.1007/s12035-014-8703-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/31/2014] [Indexed: 01/05/2023]
Abstract
Posttranslational modifications are crucial mechanisms that modulate various cellular signaling pathways, and their dysregulation is associated with many human diseases. Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disease characterized by progressive ataxia, mild cognitive impairments, difficulty with speaking and swallowing, and respiratory failure. It is caused by the expansion of an unstable CAG trinucleotide repeat encoding a glutamine tract in Ataxin-1 (ATXN1). Although the expansion of the polyglutamine tract is the key determinant of the disease, protein domains outside of the polyglutamine tract and posttranslational modifications of ATXN1 significantly alter the neurotoxicity of SCA1. ATXN1 undergoes several posttranslational modifications, including phosphorylation, ubiquitination, sumoylation, and transglutamination. Such modifications can alter the stability of ATXN1 or its activity in the regulation of target gene expression and therefore contribute to SCA1 toxicity. This review outlines different types of posttranslational modifications in ATXN1 and discusses their potential regulatory mechanisms and effects on SCA1 pathogenesis. Finally, the manipulation of posttranslational modifications as a potential therapeutic approach will be discussed.
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de Chiara C, Pastore A. Kaleidoscopic protein-protein interactions in the life and death of ataxin-1: new strategies against protein aggregation. Trends Neurosci 2014; 37:211-8. [PMID: 24636457 PMCID: PMC3988977 DOI: 10.1016/j.tins.2014.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 01/26/2014] [Accepted: 02/06/2014] [Indexed: 12/11/2022]
Abstract
Understanding how proteins protect themselves from aberrant aggregation is of primary interest for understanding basic biology, protein biochemistry, and human disease. We discuss the paradigmatic example of ataxin-1 (Atx1), the protein responsible for neurodegenerative spinocerebellar ataxia type 1 (SCA1). This disease is part of the increasing family of pathologies caused by protein aggregation and misfolding. We discuss the importance of protein-protein interactions not only in the nonpathological function of Atx1 but also in protecting the protein from aggregation and misfolding. The lessons learned from Atx1 may lead to a more general understanding of the cell's protective strategies against aggregation. The obtained knowledge may suggest a new perspective for designing specific therapeutic strategies for the cure of misfolding diseases.
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Affiliation(s)
- Cesira de Chiara
- National Institute for Medical Research (NIMR), Medical Research Council (MRC), The Ridgeway, London NW7 1AA, UK
| | - Annalisa Pastore
- Department of Clinical Neurosciences, King's College London, Denmark Hill Campus, London, UK.
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Neuroprotective function of 14-3-3 proteins in neurodegeneration. BIOMED RESEARCH INTERNATIONAL 2013; 2013:564534. [PMID: 24364034 PMCID: PMC3865737 DOI: 10.1155/2013/564534] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 10/17/2013] [Indexed: 12/21/2022]
Abstract
14-3-3 proteins are abundantly expressed adaptor proteins that interact with a vast number of binding partners to regulate their cellular localization and function. They regulate substrate function in a number of ways including protection from dephosphorylation, regulation of enzyme activity, formation of ternary complexes and sequestration. The diversity of 14-3-3 interacting partners thus enables 14-3-3 proteins to impact a wide variety of cellular and physiological processes. 14-3-3 proteins are broadly expressed in the brain, and clinical and experimental studies have implicated 14-3-3 proteins in neurodegenerative disease. A recurring theme is that 14-3-3 proteins play important roles in pathogenesis through regulating the subcellular localization of target proteins. Here, we review the evidence that 14-3-3 proteins regulate aspects of neurodegenerative disease with a focus on their protective roles against neurodegeneration.
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Candasamy AJ, Haworth RS, Cuello F, Ibrahim M, Aravamudhan S, Krüger M, Holt MR, Terracciano CMN, Mayr M, Gautel M, Avkiran M. Phosphoregulation of the titin-cap protein telethonin in cardiac myocytes. J Biol Chem 2013; 289:1282-93. [PMID: 24280220 PMCID: PMC3894314 DOI: 10.1074/jbc.m113.479030] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Telethonin (also known as titin-cap or t-cap) is a muscle-specific protein whose mutation is associated with cardiac and skeletal myopathies through unknown mechanisms. Our previous work identified cardiac telethonin as an interaction partner for the protein kinase D catalytic domain. In this study, kinase assays used in conjunction with MS and site-directed mutagenesis confirmed telethonin as a substrate for protein kinase D and Ca(2+)/calmodulin-dependent kinase II in vitro and identified Ser-157 and Ser-161 as the phosphorylation sites. Phosphate affinity electrophoresis and MS revealed endogenous telethonin to exist in a constitutively bis-phosphorylated form in isolated adult rat ventricular myocytes and in mouse and rat ventricular myocardium. Following heterologous expression in myocytes by adenoviral gene transfer, wild-type telethonin became bis-phosphorylated, whereas S157A/S161A telethonin remained non-phosphorylated. Nevertheless, both proteins localized predominantly to the sarcomeric Z-disc, where they partially replaced endogenous telethonin. Such partial replacement with S157A/S161A telethonin disrupted transverse tubule organization and prolonged the time to peak of the intracellular Ca(2+) transient and increased its variance. These data reveal, for the first time, that cardiac telethonin is constitutively bis-phosphorylated and suggest that such phosphorylation is critical for normal telethonin function, which may include maintenance of transverse tubule organization and intracellular Ca(2+) transients.
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Affiliation(s)
- Alexandra J Candasamy
- From the Cardiovascular Division, King's College London British Heart Foundation Centre, London SE1 7EH, United Kingdom
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Barclay SS, Tamura T, Ito H, Fujita K, Tagawa K, Shimamura T, Katsuta A, Shiwaku H, Sone M, Imoto S, Miyano S, Okazawa H. Systems biology analysis of Drosophila in vivo screen data elucidates core networks for DNA damage repair in SCA1. Hum Mol Genet 2013; 23:1345-64. [DOI: 10.1093/hmg/ddt524] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Roberts BJ, Reddy R, Wahl JK. Stratifin (14-3-3 σ) limits plakophilin-3 exchange with the desmosomal plaque. PLoS One 2013; 8:e77012. [PMID: 24124604 PMCID: PMC3790753 DOI: 10.1371/journal.pone.0077012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 08/27/2013] [Indexed: 11/29/2022] Open
Abstract
Desmosomes are prominent cell-cell adhesive junctions in stratified squamous epithelia and disruption of desmosomal adhesion has been shown to have dramatic effects on the function and integrity of these tissues. During normal physiologic processes, such as tissue development and wound healing, intercellular adhesion must be modified locally to allow coordinated cell movements. The mechanisms that control junction integrity and adhesive strength under these conditions are poorly understood. We utilized a proteomics approach to identify plakophilin-3 associated proteins and identified the 14-3-3 family member stratifin. Stratifin interacts specifically with plakophilin-3 and not with other plakophilin isoforms and mutation analysis demonstrated the binding site includes serine 285 in the amino terminal head domain of plakophilin-3. Stratifin interacts with a cytoplasmic pool of plakophilin-3 and is not associated with the desmosome in cultured cells. FRAP analysis revealed that decreased stratifin expression leads to an increase in the exchange rate of cytoplasmic plakophilin-3/GFP with the pool of plakophilin-3/GFP in the desmosome resulting in decreased desmosomal adhesion and increased cell migration. We propose a model by which stratifin plays a role in regulating plakophilin-3 incorporation into the desmosomal plaque by forming a plakophilin-3 stratifin complex in the cytosol and thereby affecting desmosome dynamics in squamous epithelial cells.
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Affiliation(s)
- Brett J. Roberts
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska, United States of America
| | - Roopa Reddy
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska, United States of America
| | - James K. Wahl
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska, United States of America
- * E-mail:
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Dual phosphorylation of Btk by Akt/protein kinase b provides docking for 14-3-3ζ, regulates shuttling, and attenuates both tonic and induced signaling in B cells. Mol Cell Biol 2013; 33:3214-26. [PMID: 23754751 DOI: 10.1128/mcb.00247-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bruton's tyrosine kinase (Btk) is crucial for B-lymphocyte activation and development. Mutations in the Btk gene cause X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. Using tandem mass spectrometry, 14-3-3ζ was identified as a new binding partner and negative regulator of Btk in both B-cell lines and primary B lymphocytes. The activated serine/threonine kinase Akt/protein kinase B (PKB) phosphorylated Btk on two sites prior to 14-3-3ζ binding. The interaction sites were mapped to phosphoserine pS51 in the pleckstrin homology domain and phosphothreonine pT495 in the kinase domain. The double-alanine, S51A/T495A, replacement mutant failed to bind 14-3-3ζ, while phosphomimetic aspartate substitutions, S51D/T495D, caused enhanced interaction. The phosphatidylinositol 3-kinase (PI3-kinase) inhibitor LY294002 abrogated S51/T495 phosphorylation and binding. A newly characterized 14-3-3 inhibitor, BV02, reduced binding, as did the Btk inhibitor PCI-32765 (ibrutinib). Interestingly, in the presence of BV02, phosphorylation of Btk, phospholipase Cγ2, and NF-κB increased strongly, suggesting that 14-3-3 also regulates B-cell receptor (BCR)-mediated tonic signaling. Furthermore, downregulation of 14-3-3ζ elevated nuclear translocation of Btk. The loss-of-function mutant S51A/T495A showed reduced tyrosine phosphorylation and ubiquitination. Conversely, the gain-of-function mutant S51D/T495D exhibited intense tyrosine phosphorylation, associated with Btk ubiquitination and degradation, likely contributing to the termination of BCR signaling. Collectively, this suggests that Btk could become an important new candidate for the general study of 14-3-3-mediated regulation.
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Sánchez I, Piñol P, Corral-Juan M, Pandolfo M, Matilla-Dueñas A. A novel function of Ataxin-1 in the modulation of PP2A activity is dysregulated in the spinocerebellar ataxia type 1. Hum Mol Genet 2013; 22:3425-37. [PMID: 23630944 DOI: 10.1093/hmg/ddt197] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An expansion of glutamines within the human ataxin-1 protein underlies spinocerebellar ataxia type 1 (SCA1), a dominantly inherited neurodegenerative disorder characterized by ataxia and loss of cerebellar Purkinje neurons. Although the mechanisms linking the mutation to the disease remain unclear, evidence indicates that it involves a combination of both gain and loss of functions of ataxin-1. We previously showed that the mutant ataxin-1 interacts with Anp32a, a potent and selective PP2A inhibitor, suggesting a role of PP2A in SCA1. Herein, we found a new function of ataxin-1: the modulation of Pp2a activity and the regulation of its holoenzyme composition, with the polyglutamine mutation within Atxn1 altering this function in the SCA1 mouse cerebellum before disease onset. We show that ataxin-1 enhances Pp2a-bβ expression and down-regulates Anp32a levels without affecting post-translational modifications of Pp2a catalytic subunit (Pp2a-c) known to regulate Pp2a activity. In contrast, mutant Atxn1 induces a decrease in Y307-phosphorylation in Pp2a-c, known to enhance its activity, while reducing Pp2a-b expression and inhibiting Anp32a levels. qRT-PCR and chromatin immunoprecipitation analyses show that ataxin-1-mediated regulations of the Pp2a-bβ subunit, specifically bβ2, and of Anp32a occur at the transcriptional level. The Pp2a pathway alterations were confirmed by identified phosphorylation changes of the known Pp2a-substrates, Erk2 and Gsk3β. Similarly, mutant ataxin-1-expressing SH-SY5Y cells exhibit abnormal neuritic morphology, decreased levels of both PP2A-Bβ and ANP32A, and PP2A pathway alterations, all of which are ameliorated by overexpressing ANP32A. Our results point to dysregulation of this newly assigned function of ataxin-1 in SCA1 uncovering new potential targets for therapy.
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Affiliation(s)
- Ivelisse Sánchez
- Basic, Translational and Molecular Neurogenetics Research Unit in Neurosciences, Health Sciences Research Institute Germans Trias y Pujol (IGTP), Badalona, Barcelona, Spain
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Nelson DL, Orr HT, Warren ST. The unstable repeats--three evolving faces of neurological disease. Neuron 2013; 77:825-43. [PMID: 23473314 PMCID: PMC3608403 DOI: 10.1016/j.neuron.2013.02.022] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2013] [Indexed: 01/08/2023]
Abstract
Disorders characterized by expansion of an unstable nucleotide repeat account for a number of inherited neurological diseases. Here, we review examples of unstable repeat disorders that nicely illustrate three of the major pathogenic mechanisms associated with these diseases: loss of function typically by disrupting transcription of the mutated gene, RNA toxic gain of function, and protein toxic gain of function. In addition to providing insight into the mechanisms underlying these devastating neurological disorders, the study of these unstable microsatellite repeat disorders has provided insight into very basic aspects of neuroscience.
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Affiliation(s)
- David L. Nelson
- Department of Molecular and Human Genetics, Baylor College
of Medicine, Houston, TX 77030
| | - Harry T. Orr
- Department of Laboratory Medicine and Pathology, University
of Minnesota, Minneapolis, MN 55455
| | - Stephen T. Warren
- Department of Human Genetics, Emory University School of
Medicine, Atlanta, GA 30322
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Abstract
Ataxin-1 protein expression is found in the cytoplasm and nucleus of Purkinje cells, the primary site of spinocerebellar ataxia type 1 (SCA1). Phosphorylation at S776 occurs in the cytoplasm and stabilizes the protein through interaction with 14-3-3, allowing it to translocate into the nucleus where disease is initiated. Phosphorylation and stabilization are enhanced when the polyglutamine expansion is present. In this chapter, we present a model of neurodegeneration in SCA1 initiated through phosphorylation at S776 by cAMP-dependent protein kinase (PKA) and enhanced by the presence of the polyglutamine expansion. The biological methods used to uncover SCA1 pathogenesis and phosphorylation at S776 are described.
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Affiliation(s)
- Sarita Lagalwar
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA
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Spence JL, Wallihan S. Computational prediction of the polyQ and CAG repeat spinocerebellar ataxia network based on sequence identity to untranslated regions. Gene 2012; 509:273-81. [PMID: 22967711 DOI: 10.1016/j.gene.2012.07.068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 07/30/2012] [Indexed: 01/01/2023]
Abstract
Computational prediction of biological networks would be a tremendous asset to systems biology and personalized medicine. In this paper, we use a moving window bioinformatic screen to identify transcripts with partial identity to the 5' and 3'UTRs of the polyQ spinocerebellar ataxia (SCA) genes ATXN1, ATXN2, ATXN3, ATXN7, TBP and CACNA1A and the CAG repeat expansion gene PPP2R2B. We find that the bioinformatic screen enriches for transcripts that encode proteins that interact and that have functions relevant to polyQ SCA. Transcription control and RNA binding are the primary functional groups represented in the proteins from the combined screens. The insulin growth factor pathway, the WNT pathway, long term potentiation, melanogenesis and ATM mediated DNA repair pathways were identified as important pathways. UGUUU repeats were identified as an abundant motif in the SCA network and PAXIP1, CELF2, CREBBP, EBF1, PLEKHG4, SRSF4, C5orf42, NFIA, STK24, and YWHAG were identified as statistically significant proteins in the polyQ and PPP2R2B network.
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Abstract
Ataxia is a neurological disorder characterized by loss of control of body movements. Spinocerebellar ataxia (SCA), previously known as autosomal dominant cerebellar ataxia, is a biologically robust group of close to 30 progressive neurodegenerative diseases. Six SCAs, including the more prevalent SCA1, SCA2, SCA3, and SCA6 along with SCA7 and SCA17 are caused by expansion of a CAG repeat that encodes a polyglutamine tract in the affected protein. How the mutated proteins in these polyglutamine SCAs cause disease is highly debated. Recent work suggests that the mutated protein contributes to pathogenesis within the context of its “normal” cellular function. Thus, understanding the cellular function of these proteins could aid in the development of therapeutics.
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Affiliation(s)
- Harry T Orr
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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Orr HT. SCA1-phosphorylation, a regulator of Ataxin-1 function and pathogenesis. Prog Neurobiol 2012; 99:179-85. [PMID: 22531670 DOI: 10.1016/j.pneurobio.2012.04.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 04/10/2012] [Indexed: 12/30/2022]
Abstract
Spinocerebellar ataxia type 1 (SCA1) is one an intriguing set of nine neurodegenerative diseases caused by the expansion of a unstable trinucleotide CAG repeat where the repeat is located within the coding of the affected gene, i.e. the polyglutamine (polyQ) diseases. A gain-of-function mechanism for toxicity in SCA1, like the other polyQ diseases, is thought to have a major role in pathogenesis. Yet, the specific nature of this gain-of-function is a matter of considerable discussion. An issue concerns whether toxicity stems from the native or normal function of the affected protein versus a novel function induced by polyQ expansion. For SCA1 considerable evidence is accumulating that pathology is mediated by a polyQ-induced exaggeration of a native function of the host protein Ataxin-1 (ATXN1) and that phosphorylation of S776 regulates its interaction with other cellular protein and thereby function. In addition, this posttranslational modification modulates toxicity of ATXN1 with an expanded polyglutamine.
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Affiliation(s)
- Harry T Orr
- Institute for Translational Neuroscience, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA.
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Orr HT. Polyglutamine neurodegeneration: expanded glutamines enhance native functions. Curr Opin Genet Dev 2012; 22:251-5. [PMID: 22284692 DOI: 10.1016/j.gde.2012.01.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 01/03/2012] [Indexed: 10/14/2022]
Abstract
An intriguing set of neurodegenerative disease are the nine disorders caused by the expansion of a unstable trinucleotide CAG repeat where the repeat is located within the coding of the affected gene, that is, the polyglutamine (polyQ) diseases. A gain-of-function mechanism for toxicity in polyQ diseases is widely thought to have a major role in pathogenesis. Yet, the specific nature of this gain-of-function is a matter of considerable discussion. The basic issue concerns whether toxicity stems from the native or normal function of the affected protein versus a novel function induced by polyQ expansion. For at least three of the polyQ disease considerable evidence is accumulating that pathology is mediated by a polyQ-induced exaggeration of a native function of the host protein.
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Affiliation(s)
- Harry T Orr
- Institute for Translational Neuroscience, Department of laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA.
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