1
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Haile ST, Rahman S, Fields JK, Orsburn BC, Bumpus NN, Wolberger C. The SAGA HAT module is tethered by its SWIRM domain and modulates activity of the SAGA DUB module. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194929. [PMID: 36965704 PMCID: PMC10226619 DOI: 10.1016/j.bbagrm.2023.194929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/12/2023] [Accepted: 03/19/2023] [Indexed: 03/27/2023]
Abstract
The SAGA (Spt-Ada-Gcn5 acetyltransferase) complex is a transcriptional co-activator that both acetylates and deubiquitinates histones. The histone acetyltransferase (HAT) subunit, Gcn5, is part of a subcomplex of SAGA called the HAT module. A minimal HAT module complex containing Gcn5 bound to Ada2 and Ada3 is required for full Gcn5 activity on nucleosomes. Deletion studies have suggested that the Ada2 SWIRM domain plays a role in tethering the HAT module to the remainder of SAGA. While recent cryo-EM studies have resolved the structure of the core of the SAGA complex, the HAT module subunits and molecular details of its interactions with the SAGA core could not be resolved. Here we show that the SWIRM domain is required for incorporation of the HAT module into the yeast SAGA complex, but not the ADA complex, a distinct six-protein acetyltransferase complex that includes the SAGA HAT module proteins. In the isolated Gcn5/Ada2/Ada3 HAT module, deletion of the SWIRM domain modestly increased activity but had negligible effect on nucleosome binding. Loss of the HAT module due to deletion of the SWIRM domain decreases the H2B deubiquitinating activity of SAGA, indicating a role for the HAT module in regulating SAGA DUB module activity. A model of the HAT module created with Alphafold Multimer provides insights into the structural basis for our biochemical data, as well as prior deletion studies.
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Affiliation(s)
- Sara T Haile
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, United States of America
| | - Sanim Rahman
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, United States of America
| | - James K Fields
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, United States of America
| | - Benjamin C Orsburn
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, United States of America
| | - Namandjé N Bumpus
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, United States of America
| | - Cynthia Wolberger
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, United States of America.
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2
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Wang J, Feng S, Zhang Q, Qin H, Xu C, Fu X, Yan L, Zhao Y, Yao K. Roles of Histone Acetyltransferases and Deacetylases in the Retinal Development and Diseases. Mol Neurobiol 2023; 60:2330-2354. [PMID: 36637745 DOI: 10.1007/s12035-023-03213-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/04/2023] [Indexed: 01/14/2023]
Abstract
The critical role of epigenetic modification of histones in maintaining the normal function of the nervous system has attracted increasing attention. Among these modifications, the level of histone acetylation, modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), is essential in regulating gene expression. In recent years, the research progress on the function of HDACs in retinal development and disease has advanced remarkably, while that regarding HATs remains to be investigated. Here, we overview the roles of HATs and HDACs in regulating the development of diverse retinal cells, including retinal progenitor cells, photoreceptor cells, bipolar cells, ganglion cells, and Müller glial cells. The effects of HATs and HDACs on the progression of various retinal diseases are also discussed with the highlight of the proof-of-concept research regarding the application of available HDAC inhibitors in treating retinal diseases.
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Affiliation(s)
- Jingjing Wang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Shuyu Feng
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Qian Zhang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Huan Qin
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Chunxiu Xu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Xuefei Fu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Lin Yan
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Yaqin Zhao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Kai Yao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China. .,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China. .,Hubei Province Key Laboratory of Occupational Hazard Identification and Control, Wuhan University of Science and Technology, Wuhan, 430065, China.
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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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Goswami R, Bello AI, Bean J, Costanzo KM, Omer B, Cornelio-Parra D, Odah R, Ahluwalia A, Allan SK, Nguyen N, Shores T, Aziz NA, Mohan RD. The Molecular Basis of Spinocerebellar Ataxia Type 7. Front Neurosci 2022; 16:818757. [PMID: 35401096 PMCID: PMC8987156 DOI: 10.3389/fnins.2022.818757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/07/2022] [Indexed: 11/19/2022] Open
Abstract
Spinocerebellar ataxia (SCA) type 7 (SCA7) is caused by a CAG trinucleotide repeat expansion in the ataxin 7 (ATXN7) gene, which results in polyglutamine expansion at the amino terminus of the ATXN7 protein. Although ATXN7 is expressed widely, the best characterized symptoms of SCA7 are remarkably tissue specific, including blindness and degeneration of the brain and spinal cord. While it is well established that ATXN7 functions as a subunit of the Spt Ada Gcn5 acetyltransferase (SAGA) chromatin modifying complex, the mechanisms underlying SCA7 remain elusive. Here, we review the symptoms of SCA7 and examine functions of ATXN7 that may provide further insights into its pathogenesis. We also examine phenotypes associated with polyglutamine expanded ATXN7 that are not considered symptoms of SCA7.
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Affiliation(s)
- Rituparna Goswami
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Abudu I. Bello
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Joe Bean
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Kara M. Costanzo
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Bwaar Omer
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Dayanne Cornelio-Parra
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Revan Odah
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Amit Ahluwalia
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Shefaa K. Allan
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Nghi Nguyen
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Taylor Shores
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - N. Ahmad Aziz
- Population Health Sciences, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ryan D. Mohan
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
- *Correspondence: Ryan D. Mohan,
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5
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The GCN5: its biological functions and therapeutic potentials. Clin Sci (Lond) 2021; 135:231-257. [PMID: 33443284 DOI: 10.1042/cs20200986] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 12/13/2022]
Abstract
General control non-depressible 5 (GCN5) or lysine acetyltransferase 2A (KAT2A) is one of the most highly studied histone acetyltransferases. It acts as both histone acetyltransferase (HAT) and lysine acetyltransferase (KAT). As an HAT it plays a pivotal role in the epigenetic landscape and chromatin modification. Besides, GCN5 regulates a wide range of biological events such as gene regulation, cellular proliferation, metabolism and inflammation. Imbalance in the GCN5 activity has been reported in many disorders such as cancer, metabolic disorders, autoimmune disorders and neurological disorders. Therefore, unravelling the role of GCN5 in different diseases progression is a prerequisite for both understanding and developing novel therapeutic agents of these diseases. In this review, we have discussed the structural features, the biological function of GCN5 and the mechanical link with the diseases associated with its imbalance. Moreover, the present GCN5 modulators and their limitations will be presented in a medicinal chemistry perspective.
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6
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Espinola-Lopez JM, Tan S. The Ada2/Ada3/Gcn5/Sgf29 histone acetyltransferase module. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194629. [PMID: 32890768 DOI: 10.1016/j.bbagrm.2020.194629] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 08/26/2020] [Accepted: 08/27/2020] [Indexed: 01/14/2023]
Abstract
Histone post-translational modifications are essential for the regulation of gene expression in eukaryotes. Gcn5 (KAT2A) is a histone acetyltransferase that catalyzes the post-translational modification at multiple positions of histone H3 through the transfer of acetyl groups to the free amino group of lysine residues. Gcn5 catalyzes histone acetylation in the context of a HAT module containing the Ada2, Ada3 and Sgf29 subunits of the parent megadalton SAGA transcriptional coactivator complex. Biochemical and structural studies have elucidated mechanisms for Gcn5's acetyl- and other acyltransferase activities on histone substrates, for histone H3 phosphorylation and histone H3 methylation crosstalks with histone H3 acetylation, and for how Ada2 increases Gcn5's histone acetyltransferase activity. Other studies have identified Ada2 isoforms in SAGA-related complexes and characterized variant Gcn5 HAT modules containing these Ada2 isoforms. In this review, we highlight biochemical and structural studies of Gcn5 and its functional interactions with Ada2, Ada3 and Sgf29.
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Affiliation(s)
- Jose M Espinola-Lopez
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Song Tan
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
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7
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Torres-Zelada EF, Weake VM. The Gcn5 complexes in Drosophila as a model for metazoa. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194610. [PMID: 32735945 DOI: 10.1016/j.bbagrm.2020.194610] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 01/14/2023]
Abstract
The histone acetyltransferase Gcn5 is conserved throughout eukaryotes where it functions as part of large multi-subunit transcriptional coactivator complexes that stimulate gene expression. Here, we describe how studies in the model insect Drosophila melanogaster have provided insight into the essential roles played by Gcn5 in the development of multicellular organisms. We outline the composition and activity of the four different Gcn5 complexes in Drosophila: the Spt-Ada-Gcn5 Acetyltransferase (SAGA), Ada2a-containing (ATAC), Ada2/Gcn5/Ada3 transcription activator (ADA), and Chiffon Histone Acetyltransferase (CHAT) complexes. Whereas the SAGA and ADA complexes are also present in the yeast Saccharomyces cerevisiae, ATAC has only been identified in other metazoa such as humans, and the CHAT complex appears to be unique to insects. Each of these Gcn5 complexes is nucleated by unique Ada2 homologs or splice isoforms that share conserved N-terminal domains, and differ only in their C-terminal domains. We describe the common and specialized developmental functions of each Gcn5 complex based on phenotypic analysis of mutant flies. In addition, we outline how gene expression studies in mutant flies have shed light on the different biological roles of each complex. Together, these studies highlight the key role that Drosophila has played in understanding the expanded biological function of Gcn5 in multicellular eukaryotes.
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Affiliation(s)
| | - Vikki M Weake
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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8
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Niewiadomska-Cimicka A, Hache A, Trottier Y. Gene Deregulation and Underlying Mechanisms in Spinocerebellar Ataxias With Polyglutamine Expansion. Front Neurosci 2020; 14:571. [PMID: 32581696 PMCID: PMC7296114 DOI: 10.3389/fnins.2020.00571] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/11/2020] [Indexed: 12/14/2022] Open
Abstract
Polyglutamine spinocerebellar ataxias (polyQ SCAs) include SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17 and constitute a group of adult onset neurodegenerative disorders caused by the expansion of a CAG repeat sequence located within the coding region of specific genes, which translates into polyglutamine tract in the corresponding proteins. PolyQ SCAs are characterized by degeneration of the cerebellum and its associated structures and lead to progressive ataxia and other diverse symptoms. In recent years, gene and epigenetic deregulations have been shown to play a critical role in the pathogenesis of polyQ SCAs. Here, we provide an overview of the functions of wild type and pathogenic polyQ SCA proteins in gene regulation, describe the extent and nature of gene expression changes and their pathological consequences in diseases, and discuss potential avenues to further investigate converging and distinct disease pathways and to develop therapeutic strategies.
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Affiliation(s)
- Anna Niewiadomska-Cimicka
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
| | - Antoine Hache
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
| | - Yvon Trottier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
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9
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Ji X, Jiang P, Luo J, Li M, Bai Y, Zhang J, Han B. Identification and characterization of miRNAs involved in cold acclimation of zebrafish ZF4 cells. PLoS One 2020; 15:e0226905. [PMID: 31923196 PMCID: PMC6953832 DOI: 10.1371/journal.pone.0226905] [Citation(s) in RCA: 6] [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: 07/24/2019] [Accepted: 12/07/2019] [Indexed: 12/14/2022] Open
Abstract
MicroRNAs (miRNAs) play vital roles in various biological processes under multiple stress conditions by leading to mRNA cleavage or translational repression. However, the detailed roles of miRNAs in cold acclimation in fish are still unclear. In the present study, high-throughput sequencing was performed to identify miRNAs from 6 small RNA libraries from the zebrafish embryonic fibroblast ZF4 cells under control (28°C, 30 days) and cold-acclimation (18°C, 30 days) conditions. A total of 414 miRNAs, 349 known and 65 novel, were identified. Among those miRNAs, 24 (19 known and 5 novel) were up-regulated, and 23 (9 known and 14 novel) were down-regulated in cold acclimated cells. The Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analyses indicated that the target genes of known differentially expressed miRNAs (DE-miRNA) are involved in cold acclimation by regulation of phosphorylation, cell junction, intracellular signal transduction, ECM-receptor interaction and so on. Moreover, both miR-100-3p inhibitor and miR-16b mimics could protect ZF4 cells under cold stress, indicating the involvement of miRNA in cold acclimation. Further study showed that miR-100-3p and miR-16b could regulate inversely the expression of their target gene (atad5a, cyp2ae1, lamp1, rilp, atxn7, tnika, btbd9), and that overexpression of miR-100-3p disturbed the early embryonic development of zebrafish. In summary, the present data show that miRNAs are closely involved in cold acclimation in zebrafish ZF4 cells and provide information for further understanding of the roles of miRNAs in cold acclimation in fish.
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Affiliation(s)
- Xiangqin Ji
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Penglei Jiang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Juntao Luo
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Mengjia Li
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Yajing Bai
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Junfang Zhang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
- International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai, China
| | - Bingshe Han
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- * E-mail:
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10
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Niewiadomska-Cimicka A, Trottier Y. Molecular Targets and Therapeutic Strategies in Spinocerebellar Ataxia Type 7. Neurotherapeutics 2019; 16:1074-1096. [PMID: 31432449 PMCID: PMC6985300 DOI: 10.1007/s13311-019-00778-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Spinocerebellar ataxia type 7 (SCA7) is a rare autosomal dominant neurodegenerative disorder characterized by progressive neuronal loss in the cerebellum, brainstem, and retina, leading to cerebellar ataxia and blindness as major symptoms. SCA7 is due to the expansion of a CAG triplet repeat that is translated into a polyglutamine tract in ATXN7. Larger SCA7 expansions are associated with earlier onset of symptoms and more severe and rapid disease progression. Here, we summarize the pathological and genetic aspects of SCA7, compile the current knowledge about ATXN7 functions, and then focus on recent advances in understanding the pathogenesis and in developing biomarkers and therapeutic strategies. ATXN7 is a bona fide subunit of the multiprotein SAGA complex, a transcriptional coactivator harboring chromatin remodeling activities, and plays a role in the differentiation of photoreceptors and Purkinje neurons, two highly vulnerable neuronal cell types in SCA7. Polyglutamine expansion in ATXN7 causes its misfolding and intranuclear accumulation, leading to changes in interactions with native partners and/or partners sequestration in insoluble nuclear inclusions. Studies of cellular and animal models of SCA7 have been crucial to unveil pathomechanistic aspects of the disease, including gene deregulation, mitochondrial and metabolic dysfunctions, cell and non-cell autonomous protein toxicity, loss of neuronal identity, and cell death mechanisms. However, a better understanding of the principal molecular mechanisms by which mutant ATXN7 elicits neurotoxicity, and how interconnected pathogenic cascades lead to neurodegeneration is needed for the development of effective therapies. At present, therapeutic strategies using nucleic acid-based molecules to silence mutant ATXN7 gene expression are under development for SCA7.
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Affiliation(s)
- Anna Niewiadomska-Cimicka
- Institute of Genetic and Molecular and Cellular Biology (IGBMC), Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U1258), University of Strasbourg, Illkirch, France
| | - Yvon Trottier
- Institute of Genetic and Molecular and Cellular Biology (IGBMC), Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U1258), University of Strasbourg, Illkirch, France.
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11
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Jiang Y, Berg MD, Genereaux J, Ahmed K, Duennwald ML, Brandl CJ, Lajoie P. Sfp1 links TORC1 and cell growth regulation to the yeast SAGA‐complex component Tra1 in response to polyQ proteotoxicity. Traffic 2019; 20:267-283. [DOI: 10.1111/tra.12637] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/08/2019] [Accepted: 02/08/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Yuwei Jiang
- Department of Anatomy and Cell BiologyThe University of Western Ontario London Ontario Canada
| | - Matthew D. Berg
- Department of BiochemistryThe University of Western Ontario London Ontario Canada
| | - Julie Genereaux
- Department of Anatomy and Cell BiologyThe University of Western Ontario London Ontario Canada
- Department of BiochemistryThe University of Western Ontario London Ontario Canada
| | - Khadija Ahmed
- Department of Anatomy and Cell BiologyThe University of Western Ontario London Ontario Canada
| | - Martin L. Duennwald
- Department of Anatomy and Cell BiologyThe University of Western Ontario London Ontario Canada
- Department of Pathology and Laboratory MedicineThe University of Western Ontario London Ontario Canada
| | | | - Patrick Lajoie
- Department of Anatomy and Cell BiologyThe University of Western Ontario London Ontario Canada
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12
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Xiang C, Zhang S, Dong X, Ma S, Cong S. Transcriptional Dysregulation and Post-translational Modifications in Polyglutamine Diseases: From Pathogenesis to Potential Therapeutic Strategies. Front Mol Neurosci 2018; 11:153. [PMID: 29867345 PMCID: PMC5962650 DOI: 10.3389/fnmol.2018.00153] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/20/2018] [Indexed: 02/06/2023] Open
Abstract
Polyglutamine (polyQ) diseases are hereditary neurodegenerative disorders caused by an abnormal expansion of a trinucleotide CAG repeat in the coding region of their respective associated genes. PolyQ diseases mainly display progressive degeneration of the brain and spinal cord. Nine polyQ diseases are known, including Huntington's disease (HD), spinal and bulbar muscular atrophy (SBMA), dentatorubral-pallidoluysian atrophy (DRPLA), and six forms of spinocerebellar ataxia (SCA). HD is the best characterized polyQ disease. Many studies have reported that transcriptional dysregulation and post-translational disruptions, which may interact with each other, are central features of polyQ diseases. Post-translational modifications, such as the acetylation of histones, are closely associated with the regulation of the transcriptional activity. A number of groups have studied the interactions between the polyQ proteins and transcription factors. Pharmacological drugs or genetic manipulations aimed at correcting the dysregulation have been confirmed to be effective in the treatment of polyQ diseases in many animal and cellular models. For example, histone deaceylase inhibitors have been demonstrated to have beneficial effects in cases of HD, SBMA, DRPLA, and SCA3. In this review, we describe the transcriptional and post-translational dysregulation in polyQ diseases with special focus on HD, and we summarize and comment on potential treatment approaches targeting disruption of transcription and post-translation processes in these diseases.
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Affiliation(s)
| | | | | | | | - Shuyan Cong
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, China
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Melo-Cardenas J, Zhang Y, Zhang DD, Fang D. Ubiquitin-specific peptidase 22 functions and its involvement in disease. Oncotarget 2018; 7:44848-44856. [PMID: 27057639 PMCID: PMC5190139 DOI: 10.18632/oncotarget.8602] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/10/2016] [Indexed: 12/24/2022] Open
Abstract
Deubiquitylases remove ubiquitin moieties from different substrates to regulate protein activity and cell homeostasis. Since this posttranslational modification plays a role in several different cellular functions, its deregulation has been associated with different pathologies. Aberrant expression of the Ubiquitin-Specific Peptidase 22 (USP22) has been associated with poor cancer prognosis and neurological disorders. However, little is known about USP22 role in these pathologies or in normal physiology. This review summarizes the current knowledge about USP22 function from yeast to human and provides an overview of the possible mechanisms by which USP22 is emerging as a potential oncogene.
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Affiliation(s)
- Johanna Melo-Cardenas
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Yusi Zhang
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Donna D Zhang
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Deyu Fang
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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14
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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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Kalvala A, Gao L, Aguila B, Dotts K, Rahman M, Nana-Sinkam SP, Zhou X, Wang QE, Amann J, Otterson GA, Villalona-Calero MA, Duan W. Rad51C-ATXN7 fusion gene expression in colorectal tumors. Mol Cancer 2016; 15:47. [PMID: 27296891 PMCID: PMC4906819 DOI: 10.1186/s12943-016-0527-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 05/20/2016] [Indexed: 11/10/2022] Open
Abstract
Background Fusion proteins have unique oncogenic properties and their identification can be useful either as diagnostic or therapeutic targets. Next generation sequencing data have previously shown a fusion gene formed between Rad51C and ATXN7 genes in the MCF7 breast cancer cell line. However, the existence of this fusion gene in colorectal patient tumor tissues is largely still unknown. Methods We evaluated for the presence of Rad51C-ATXN7 fusion gene in colorectal tumors and cells by RT-PCR, PCR, Topo TA cloning, Real time PCR, immunoprecipitation and immunoblotting techniques. Results We identified two forms of fusion mRNAs between Rad51C and ATXN7 in the colorectal tumors, including a Variant 1 (fusion transcript between Rad51C exons 1–7 and ATXN7 exons 6–13), and a Variant 2 (between Rad51C exons 1–6 and ATXN7 exons 6–13). In silico analysis showed that the Variant 1 produces a truncated protein, whereas the Variant 2 was predicted to produce a fusion protein with molecular weight of 110 KDa. Immunoprecipitation and Western blot analysis further showed a 110 KDa protein in colorectal tumors. 5-Azacytidine treatment of LS-174 T cells caused a 3.51-fold increase in expression of the fusion gene (Variant 2) as compared to no treatment controls evaluated by real time PCR. Conclusion In conclusion we found a fusion gene between DNA repair gene Rad51C and neuro-cerebral ataxia Ataxin-7 gene in colorectal tumors. The in-frame fusion transcript of Variant 2 results in a fusion protein with molecular weight of 110 KDa. In addition, we found that expression of fusion gene is associated with functional impairment of Fanconi Anemia (FA) DNA repair pathway in colorectal tumors. The expression of Rad51C-ATXN7 in tumors warrants further investigation, as it suggests the potential of the fusion gene in treatment and predictive value in colorectal cancers. Electronic supplementary material The online version of this article (doi:10.1186/s12943-016-0527-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Arjun Kalvala
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Li Gao
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Brittany Aguila
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Kathleen Dotts
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Mohammad Rahman
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Serge P Nana-Sinkam
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA.,Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Xiaoping Zhou
- Department of Pathology, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Qi-En Wang
- Department of Radiology, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Joseph Amann
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA.,Division of Medical Oncology Department of Internal Medicine, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Gregory A Otterson
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA.,Division of Medical Oncology Department of Internal Medicine, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA
| | - Miguel A Villalona-Calero
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA. .,Division of Medical Oncology Department of Internal Medicine, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA. .,Department of Pharmacology, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA.
| | - Wenrui Duan
- Comprehensive Cancer Center, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA. .,Division of Medical Oncology Department of Internal Medicine, the Ohio State University College of Medicine and Public Health, Columbus, Ohio, 43210, USA.
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Durand A, Bonnet J, Fournier M, Chavant V, Schultz P. Mapping the deubiquitination module within the SAGA complex. Structure 2015; 22:1553-9. [PMID: 25441028 DOI: 10.1016/j.str.2014.07.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 07/25/2014] [Accepted: 07/25/2014] [Indexed: 11/25/2022]
Abstract
The molecular organization of the yeast transcriptional coactivator Spt-Ada-Gcn5 acetyltransferase (SAGA) was analyzed by single-particle electron microscopy. Complete or partial deletion of the Sgf73 subunit disconnects the deubiquitination (DUB) module from SAGA and favors in our conditions the cleavage of the C-terminal ends of the Spt7 subunit and the loss of the Spt8 subunit. The structural comparison of the wild-type SAGA with two deletion mutants positioned the DUB module and enabled the fitting of the available atomic models. The localization of the DUB module close to Gcn5 defines a chromatin-binding interface within SAGA, which could be demonstrated by the binding of nucleosome core particles. The TATA-box binding protein (TBP)-interacting subunit Spt8 was found to be located close to the DUB but in a different domain than Spt3, also known to contact TBP. A flexible protein arm brings both subunits close enough to interact simultaneously with TBP.
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17
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Guyenet SJ, Mookerjee SS, Lin A, Custer SK, Chen SF, Sopher BL, La Spada AR, Ellerby LM. Proteolytic cleavage of ataxin-7 promotes SCA7 retinal degeneration and neurological dysfunction. Hum Mol Genet 2015; 24:3908-17. [PMID: 25859008 DOI: 10.1093/hmg/ddv121] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 04/07/2015] [Indexed: 11/12/2022] Open
Abstract
The neurodegenerative disorder spinocerebellar ataxia type 7 (SCA7) is caused by a polyglutamine (polyQ) expansion in the ataxin-7 protein, categorizing SCA7 as one member of a large class of heritable neurodegenerative proteinopathies. Cleavage of ataxin-7 by the protease caspase-7 has been demonstrated in vitro, and the accumulation of proteolytic cleavage products in SCA7 patients and mouse models has been identified as an early pathological change. However, it remains unknown whether a causal relationship exists between ataxin-7 proteolysis and in vivo SCA7 disease progression. To determine whether caspase cleavage is a critical event in SCA7 disease pathogenesis, we generated transgenic mice expressing polyQ-expanded ataxin-7 with a second-site mutation (D266N) to prevent caspase-7 proteolysis. When we compared SCA7-D266N mice with SCA7 mice lacking the D266N mutation, we found that SCA7-D266N mice exhibited improved motor performance, reduced neurodegeneration and substantial lifespan extension. Our findings indicate that proteolysis at the D266 caspase-7 cleavage site is an important mediator of ataxin-7 neurotoxicity, suggesting that inhibition of caspase-7 cleavage of polyQ-ataxin-7 may be a promising therapeutic strategy for this untreatable disorder.
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Affiliation(s)
| | | | - Amy Lin
- The Buck Institute for Research on Aging, Novato, CA 94945, USA
| | | | - Sylvia F Chen
- The Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Bryce L Sopher
- Department of Neurology, University of Washington, Seattle, WA, USA
| | - Albert R La Spada
- Department of Medicine (Medical Genetics) and Department of Cellular and Molecular Medicine, Division of Biological Sciences, Institute for Genomic Medicine, and the Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA, USA, Department of Neurosciences, Division of Biological Sciences, Institute for Genomic Medicine, and the Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA, USA, Department of Pediatrics, Division of Biological Sciences, Institute for Genomic Medicine, and the Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA, USA and Rady Children's Hospital, San Diego, CA 92123, USA
| | - Lisa M Ellerby
- The Buck Institute for Research on Aging, Novato, CA 94945, USA,
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18
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Poly(Q) Expansions in ATXN7 Affect Solubility but Not Activity of the SAGA Deubiquitinating Module. Mol Cell Biol 2015; 35:1777-87. [PMID: 25755283 DOI: 10.1128/mcb.01454-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/02/2015] [Indexed: 11/20/2022] Open
Abstract
Spinocerebellar ataxia type 7 (SCA7) is a debilitating neurodegenerative disease caused by expansion of a polyglutamine [poly(Q)] tract in ATXN7, a subunit of the deubiquitinase (DUB) module (DUBm) in the SAGA complex. The effects of ATXN7-poly(Q) on DUB activity are not known. To address this important question, we reconstituted the DUBm in vitro with either wild-type ATXN7 or a pathogenic form, ATXN7-92Q NT, with 92 Q residues at the N terminus (NT). We found that both forms of ATXN7 greatly enhance DUB activity but that ATXN7-92Q NT is largely insoluble unless it is incorporated into the DUBm. Cooverexpression of DUBm components in human astrocytes also promoted the solubility of ATXN7-92Q, inhibiting its aggregation into nuclear inclusions that sequester DUBm components, leading to global increases in ubiquitinated H2B (H2Bub) levels. Global H2Bub levels were also increased in the cerebellums of mice in a SCA7 mouse model. Our findings indicate that although ATXN7 poly(Q) expansions do not change the enzymatic activity of the DUBm, they likely contribute to SCA7 by initiating aggregates that sequester the DUBm away from its substrates.
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19
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Han Y, Luo J, Ranish J, Hahn S. Architecture of the Saccharomyces cerevisiae SAGA transcription coactivator complex. EMBO J 2014; 33:2534-46. [PMID: 25216679 DOI: 10.15252/embj.201488638] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The conserved transcription coactivator SAGA is comprised of several modules that are involved in activator binding, TBP binding, histone acetylation (HAT) and deubiquitination (DUB). Crosslinking and mass spectrometry, together with genetic and biochemical analyses, were used to determine the molecular architecture of the SAGA-TBP complex. We find that the SAGA Taf and Taf-like subunits form a TFIID-like core complex at the center of SAGA that makes extensive interactions with all other SAGA modules. SAGA-TBP binding involves a network of interactions between subunits Spt3, Spt8, Spt20, and Spt7. The HAT and DUB modules are in close proximity, and the DUB module modestly stimulates HAT function. The large activator-binding subunit Tra1 primarily connects to the TFIID-like core via its FAT domain. These combined results were used to derive a model for the arrangement of the SAGA subunits and its interactions with TBP. Our results provide new insight into SAGA function in gene regulation, its structural similarity with TFIID, and functional interactions between the SAGA modules.
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Affiliation(s)
- Yan Han
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA Biological Physics, Structure and Design Program, University of Washington, Seattle, WA, USA
| | - Jie Luo
- Institute for Systems Biology, Seattle, WA, USA
| | | | - Steven Hahn
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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Mohan RD, Abmayr SM, Workman JL. The expanding role for chromatin and transcription in polyglutamine disease. Curr Opin Genet Dev 2014; 26:96-104. [PMID: 25108806 DOI: 10.1016/j.gde.2014.06.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 06/22/2014] [Accepted: 06/25/2014] [Indexed: 11/28/2022]
Abstract
Nine genetic diseases arise from expansion of CAG repeats in seemingly unrelated genes. They are referred to as polyglutamine (polyQ) diseases due to the presence of elongated glutamine tracts in the corresponding proteins. The pathologic consequences of polyQ expansion include progressive spinal, cerebellar, and neural degeneration. These pathologies are not identical, however, suggesting that disruption of protein-specific functions is crucial to establish and maintain each disease. A closer examination of protein function reveals that several act as regulators of gene expression. Here we examine the roles these proteins play in regulating gene expression, discuss how polyQ expansion may disrupt these functions to cause disease, and speculate on the neural specificity of perturbing ubiquitous gene regulators.
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Affiliation(s)
- Ryan D Mohan
- Stowers Institute for Medical Research, 1000 E 50th St., Kansas City, MO 64110, USA
| | - Susan M Abmayr
- Stowers Institute for Medical Research, 1000 E 50th St., Kansas City, MO 64110, USA.
| | - Jerry L Workman
- Stowers Institute for Medical Research, 1000 E 50th St., Kansas City, MO 64110, USA.
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21
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Mohan RD, Abmayr SM, Workman JL. Pulling complexes out of complex diseases: Spinocerebellar Ataxia 7. Rare Dis 2014; 2:e28859. [PMID: 25054097 PMCID: PMC4091419 DOI: 10.4161/rdis.28859] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/06/2014] [Accepted: 04/11/2014] [Indexed: 11/19/2022] Open
Abstract
Spinocerebellar ataxia 7 (SCA7) is an incurable disease caused by expansion of CAG trinucleotide sequences within the Ataxin-7 gene. This elongated CAG tract results in an Ataxin-7 protein bearing an expanded polyglutamine (PolyQ) repeat. SCA7 disease is characterized by progressive neural and retinal degeneration leading to ataxia and blindness. Evidence gathered from investigating SCA7 and other PolyQ diseases strongly suggest that misregulation of gene expression contributes to neurodegeneration. In fact, Ataxin-7 is a subunit of the essential Spt-Ada-Gcn5-Acetltransferase (SAGA) chromatin modifying complex that regulates expression of a large number of genes. Here we discuss recent insights into Ataxin-7 function and, considering these findings, propose a model for how polyglutamine expansion of Ataxin-7 may affect Ataxin-7 function to alter chromatin modifications and gene expression.
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Affiliation(s)
- Ryan D Mohan
- Stowers Institute for Medical Research; Kansas City, MO USA
| | - Susan M Abmayr
- Stowers Institute for Medical Research; Kansas City, MO USA
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