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Jia X, He X, Huang C, Li J, Dong Z, Liu K. Protein translation: biological processes and therapeutic strategies for human diseases. Signal Transduct Target Ther 2024; 9:44. [PMID: 38388452 PMCID: PMC10884018 DOI: 10.1038/s41392-024-01749-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 01/13/2024] [Accepted: 01/18/2024] [Indexed: 02/24/2024] Open
Abstract
Protein translation is a tightly regulated cellular process that is essential for gene expression and protein synthesis. The deregulation of this process is increasingly recognized as a critical factor in the pathogenesis of various human diseases. In this review, we discuss how deregulated translation can lead to aberrant protein synthesis, altered cellular functions, and disease progression. We explore the key mechanisms contributing to the deregulation of protein translation, including functional alterations in translation factors, tRNA, mRNA, and ribosome function. Deregulated translation leads to abnormal protein expression, disrupted cellular signaling, and perturbed cellular functions- all of which contribute to disease pathogenesis. The development of ribosome profiling techniques along with mass spectrometry-based proteomics, mRNA sequencing and single-cell approaches have opened new avenues for detecting diseases related to translation errors. Importantly, we highlight recent advances in therapies targeting translation-related disorders and their potential applications in neurodegenerative diseases, cancer, infectious diseases, and cardiovascular diseases. Moreover, the growing interest lies in targeted therapies aimed at restoring precise control over translation in diseased cells is discussed. In conclusion, this comprehensive review underscores the critical role of protein translation in disease and its potential as a therapeutic target. Advancements in understanding the molecular mechanisms of protein translation deregulation, coupled with the development of targeted therapies, offer promising avenues for improving disease outcomes in various human diseases. Additionally, it will unlock doors to the possibility of precision medicine by offering personalized therapies and a deeper understanding of the molecular underpinnings of diseases in the future.
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Affiliation(s)
- Xuechao Jia
- Department of Pathophysiology, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, 450000, China
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, Henan, 450000, China
| | - Xinyu He
- Department of Pathophysiology, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, 450000, China
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, Henan, 450000, China
| | - Chuntian Huang
- Department of Pathology and Pathophysiology, Henan University of Chinese Medicine, Zhengzhou, Henan, 450000, China
| | - Jian Li
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, Henan, 450000, China
| | - Zigang Dong
- Department of Pathophysiology, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, 450000, China.
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, Henan, 450000, China.
- Tianjian Laboratory of Advanced Biomedical Sciences, Zhengzhou, Henan, 450052, China.
- Research Center for Basic Medicine Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450052, Henan, China.
- Provincial Cooperative Innovation Center for Cancer Chemoprevention, Zhengzhou University, Zhengzhou, Henan, 450000, China.
| | - Kangdong Liu
- Department of Pathophysiology, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, 450000, China.
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, Henan, 450000, China.
- Tianjian Laboratory of Advanced Biomedical Sciences, Zhengzhou, Henan, 450052, China.
- Research Center for Basic Medicine Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450052, Henan, China.
- Provincial Cooperative Innovation Center for Cancer Chemoprevention, Zhengzhou University, Zhengzhou, Henan, 450000, China.
- State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, Henan, 450000, China.
- The Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan, 450000, China.
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2
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Poulis P, Peske F, Rodnina MV. The many faces of ribosome translocation along the mRNA: reading frame maintenance, ribosome frameshifting and translational bypassing. Biol Chem 2023; 404:755-767. [PMID: 37077160 DOI: 10.1515/hsz-2023-0142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 03/22/2023] [Indexed: 04/21/2023]
Abstract
In each round of translation elongation, the ribosome translocates along the mRNA by precisely one codon. Translocation is promoted by elongation factor G (EF-G) in bacteria (eEF2 in eukaryotes) and entails a number of precisely-timed large-scale structural rearrangements. As a rule, the movements of the ribosome, tRNAs, mRNA and EF-G are orchestrated to maintain the exact codon-wise step size. However, signals in the mRNA, as well as environmental cues, can change the timing and dynamics of the key rearrangements leading to recoding of the mRNA into production of trans-frame peptides from the same mRNA. In this review, we discuss recent advances on the mechanics of translocation and reading frame maintenance. Furthermore, we describe the mechanisms and biological relevance of non-canonical translocation pathways, such as hungry and programmed frameshifting and translational bypassing, and their link to disease and infection.
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Affiliation(s)
- Panagiotis Poulis
- Department of Physical Biochemistry, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Frank Peske
- Department of Physical Biochemistry, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany
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3
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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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4
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Wright SE, Rodriguez CM, Monroe J, Xing J, Krans A, Flores BN, Barsur V, Ivanova MI, Koutmou KS, Barmada SJ, Todd PK. CGG repeats trigger translational frameshifts that generate aggregation-prone chimeric proteins. Nucleic Acids Res 2022; 50:8674-8689. [PMID: 35904811 PMCID: PMC9410890 DOI: 10.1093/nar/gkac626] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/13/2022] [Indexed: 11/25/2022] Open
Abstract
CGG repeat expansions in the FMR1 5’UTR cause the neurodegenerative disease Fragile X-associated tremor/ataxia syndrome (FXTAS). These repeats form stable RNA secondary structures that support aberrant translation in the absence of an AUG start codon (RAN translation), producing aggregate-prone peptides that accumulate within intranuclear neuronal inclusions and contribute to neurotoxicity. Here, we show that the most abundant RAN translation product, FMRpolyG, is markedly less toxic when generated from a construct with a non-repetitive alternating codon sequence in place of the CGG repeat. While exploring the mechanism of this differential toxicity, we observed a +1 translational frameshift within the CGG repeat from the arginine to glycine reading frame. Frameshifts occurred within the first few translated repeats and were triggered predominantly by RNA sequence and structural features. Short chimeric R/G peptides form aggregates distinct from those formed by either pure arginine or glycine, and these chimeras induce toxicity in cultured rodent neurons. Together, this work suggests that CGG repeats support translational frameshifting and that chimeric RAN translated peptides may contribute to CGG repeat-associated toxicity in FXTAS and related disorders.
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Affiliation(s)
- Shannon E Wright
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Caitlin M Rodriguez
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Genetics, Stanford University School of Medicine, Stanford, CA 84305, USA
| | - Jeremy Monroe
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jiazheng Xing
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Amy Krans
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.,VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
| | - Brittany N Flores
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.,Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Venkatesha Barsur
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Magdalena I Ivanova
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.,Biophysics Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kristin S Koutmou
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sami J Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.,VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
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Kotowska-Zimmer A, Przybyl L, Pewinska M, Suszynska-Zajczyk J, Wronka D, Figiel M, Olejniczak M. A CAG repeat-targeting artificial miRNA lowers the mutant huntingtin level in the YAC128 model of Huntington's disease. MOLECULAR THERAPY - NUCLEIC ACIDS 2022; 28:702-715. [PMID: 35664700 PMCID: PMC9126840 DOI: 10.1016/j.omtn.2022.04.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 04/29/2022] [Indexed: 12/12/2022]
Abstract
Among the many proposed therapeutic strategies for Huntington's disease (HD), allele-selective therapies are the most desirable but also the most challenging. RNA interference (RNAi) tools that target CAG repeats selectively reduce the mutant huntingtin level in cellular models of HD. The purpose of this study was to test the efficacy, selectivity, and safety of two vector-based RNAi triggers in an animal model of HD. CAG repeat-targeting short hairpin RNA (shRNA) and artificial miRNA (amiRNA) were delivered to the brains of YAC128 mice via intrastriatal injection of AAV5 vectors. Molecular tests demonstrated that both the shRNA and amiRNA reduced the mutant huntingtin level by 50% without influencing endogenous mouse huntingtin. In addition, a concentration-dependent reduction in HTT aggregates in the striatum was observed. In contrast to the shRNA, the amiRNA was well tolerated and did not show signs of toxicity during the course of the experiment up to 20 weeks post injection. Interestingly, amiRNA treatment reduced the spleen weight to values characteristic of healthy (WT) mice and improved motor performance on the static rod test. These preclinical data demonstrate that the CAG-targeting strategy and amiRNA could make an original and valuable contribution to currently used therapeutic approaches for HD.
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Affiliation(s)
- Anna Kotowska-Zimmer
- Department of Genome Engineering, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Lukasz Przybyl
- Laboratory of Mammalian Model Organisms, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Marianna Pewinska
- Department of Genome Engineering, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Joanna Suszynska-Zajczyk
- Department of Biochemistry and Biotechnology, Poznan University of Life Sciences, 60-632 Poznan, Poland
| | - Dorota Wronka
- Laboratory of Mammalian Model Organisms, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Maciej Figiel
- Department of Molecular Neurobiology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Marta Olejniczak
- Department of Genome Engineering, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
- Corresponding author Marta Olejniczak, Department of Genome Engineering, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
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6
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Jazurek-Ciesiolka M, Ciesiolka A, Komur AA, Urbanek-Trzeciak MO, Krzyzosiak WJ, Fiszer A. RAN Translation of the Expanded CAG Repeats in the SCA3 Disease Context. J Mol Biol 2020; 432:166699. [PMID: 33157084 DOI: 10.1016/j.jmb.2020.10.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 10/26/2020] [Accepted: 10/26/2020] [Indexed: 01/08/2023]
Abstract
Spinocerebellar ataxia type 3 (SCA3) is a progressive neurodegenerative disorder caused by a CAG repeat expansion in the ATXN3 gene encoding the ataxin-3 protein. Despite extensive research the exact pathogenic mechanisms of SCA3 are still not understood in depth. In the present study, to gain insight into the toxicity induced by the expanded CAG repeats in SCA3, we comprehensively investigated repeat-associated non-ATG (RAN) translation in various cellular models expressing translated or non-canonically translated ATXN3 sequences with an increasing number of CAG repeats. We demonstrate that two SCA3 RAN proteins, polyglutamine (polyQ) and polyalanine (polyA), are found only in the case of CAG repeats of pathogenic length. Despite having distinct cellular localization, RAN polyQ and RAN polyA proteins are very often coexpressed in the same cell, impairing nuclear integrity and inducing apoptosis. We provide for the first time mechanistic insights into SCA3 RAN translation indicating that ATXN3 sequences surrounding the repeat region have an impact on SCA3 RAN translation initiation and efficiency. We revealed that RAN translation of polyQ proteins starts at non-cognate codons upstream of the CAG repeats, whereas RAN polyA proteins are likely translated within repeats. Furthermore, integrated stress response activation enhances SCA3 RAN translation. Our findings suggest that the ATXN3 sequence context plays an important role in triggering SCA3 RAN translation and that SCA3 RAN proteins may cause cellular toxicity.
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Affiliation(s)
- Magdalena Jazurek-Ciesiolka
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
| | - Adam Ciesiolka
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Alicja A Komur
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Martyna O Urbanek-Trzeciak
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Agnieszka Fiszer
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
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7
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Abstract
Identification of repeat-associated non-AUG (RAN) translation in trinucleotide (CAG) repeat diseases has led to the emerging concept that CAG repeat diseases are caused by nonpolyglutamine products. Nonetheless, the in vivo contribution of RAN translation to the pathogenesis of CAG repeat diseases remains elusive. Via CRISPR/Cas9-mediated genome editing, we established knock-in mouse models that harbor expanded CAG repeats in the mouse huntingtin gene to express RAN-translated products with or without polyglutamine peptides. We found that RAN translation is not detected in the knock-in mouse models when expanded CAG repeats are expressed at the endogenous level. Consistently, the expanded CAG repeats that cannot be translated into polyglutamine repeats do not yield the neuropathological and behavioral phenotypes that were found in knock-in mice expressing expanded polyglutamine repeats. Our findings suggest that RAN-translated products do not play a major role in the pathogenesis of CAG repeat diseases and underscore the importance in targeting polyglutamine repeats for therapeutics.
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8
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Primary Neurons and Differentiated NSC-34 Cells Are More Susceptible to Arginine-Rich ALS Dipeptide Repeat Protein-Associated Toxicity than Non-Differentiated NSC-34 and CHO Cells. Int J Mol Sci 2019; 20:ijms20246238. [PMID: 31835664 PMCID: PMC6941034 DOI: 10.3390/ijms20246238] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/02/2019] [Accepted: 12/09/2019] [Indexed: 12/14/2022] Open
Abstract
A repeat expansion mutation in the C9orf72 gene is the most common known genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In this study, using multiple cell-based assay systems, we reveal both increased dipeptide repeat protein (DRP) toxicity in primary neurons and in differentiated neuronal cell lines. Using flow cytometry and confocal laser scanning microscopy of cells treated with fluorescein isothiocyanate (FITC)-labeled DRPs, we confirm that poly-glycine-arginine (GR) and poly-proline-arginine (PR) DRPs entered cells more readily than poly-glycine-proline (GP) and poly-proline-alanine (PA) DRPs. Our findings suggest that the toxicity of C9-DRPs may be influenced by properties associated with differentiated and aging motor neurons. Further, our findings provide sensitive cell-based assay systems to test phenotypic rescue ability of potential interventions.
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9
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Jiang J, Ravits J. Pathogenic Mechanisms and Therapy Development for C9orf72 Amyotrophic Lateral Sclerosis/Frontotemporal Dementia. Neurotherapeutics 2019; 16:1115-1132. [PMID: 31667754 PMCID: PMC6985338 DOI: 10.1007/s13311-019-00797-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In 2011, a hexanucleotide repeat expansion in the first intron of the C9orf72 gene was identified as the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The proposed disease mechanisms include loss of C9orf72 function and gain of toxicity from the bidirectionally transcribed repeat-containing RNAs. Over the last few years, substantial progress has been made to determine the contribution of loss and gain of function in disease pathogenesis. The extensive body of molecular, cellular, animal, and human neuropathological studies is conflicted, but the predominance of evidence favors gain of toxicity as the main pathogenic mechanism for C9orf72 repeat expansions. Alterations in several downstream cellular functions, such as nucleocytoplasmic transport and autophagy, are implicated. Exciting progress has also been made in therapy development targeting this mutation, such as by antisense oligonucleotide therapies targeting sense transcripts and small molecules targeting nucleocytoplasmic transport, and these are now in phase 1 clinical trials.
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Affiliation(s)
- Jie Jiang
- Department of Cell Biology, Emory University, Atlanta, GA, 30322, USA.
| | - John Ravits
- Department of Neurosciences, University of California at San Diego, La Jolla, CA, 92093, USA.
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10
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Murata A, Nakamori M, Nakatani K. Modulating RNA secondary and tertiary structures by mismatch binding ligands. Methods 2019; 167:78-91. [DOI: 10.1016/j.ymeth.2019.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 05/05/2019] [Accepted: 05/07/2019] [Indexed: 12/21/2022] Open
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11
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Rodriguez CM, Todd PK. New pathologic mechanisms in nucleotide repeat expansion disorders. Neurobiol Dis 2019; 130:104515. [PMID: 31229686 DOI: 10.1016/j.nbd.2019.104515] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/07/2019] [Accepted: 06/19/2019] [Indexed: 12/14/2022] Open
Abstract
Tandem microsatellite repeats are common throughout the human genome and intrinsically unstable, exhibiting expansions and contractions both somatically and across generations. Instability in a small subset of these repeats are currently linked to human disease, although recent findings suggest more disease-causing repeats await discovery. These nucleotide repeat expansion disorders (NREDs) primarily affect the nervous system and commonly lead to neurodegeneration through toxic protein gain-of-function, protein loss-of-function, and toxic RNA gain-of-function mechanisms. However, the lines between these categories have blurred with recent findings of unconventional Repeat Associated Non-AUG (RAN) translation from putatively non-coding regions of the genome. Here we review two emerging topics in NREDs: 1) The mechanisms by which RAN translation occurs and its role in disease pathogenesis and 2) How nucleotide repeats as RNA and translated proteins influence liquid-liquid phase separation, membraneless organelle dynamics, and nucleocytoplasmic transport. We examine these topics with a particular eye on two repeats: the CGG repeat expansion responsible for Fragile X syndrome and Fragile X-associated Tremor Ataxia Syndrome (FXTAS) and the intronic GGGGCC repeat expansion in C9orf72, the most common inherited cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Our thesis is that these emerging disease mechanisms can inform a broader understanding of the native roles of microsatellites in cellular function and that aberrations in these native processes provide clues to novel therapeutic strategies for these currently untreatable disorders.
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Affiliation(s)
- C M Rodriguez
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Department of Genetics, Stanford University, Stanford, CA, USA
| | - P 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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12
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Alberti S, Carra S. Quality Control of Membraneless Organelles. J Mol Biol 2018; 430:4711-4729. [PMID: 29758260 DOI: 10.1016/j.jmb.2018.05.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/04/2018] [Accepted: 05/04/2018] [Indexed: 02/06/2023]
Abstract
The formation of membraneless organelles (MLOs) by phase separation has emerged as a new way of organizing the cytoplasm and nucleoplasm of cells. Examples of MLOs forming via phase separation are nucleoli in the nucleus and stress granules in the cytoplasm. The main components of these MLOs are macromolecules such as RNAs and proteins. In order to assemble by phase separation, these proteins and RNAs have to undergo many cooperative interactions. These cooperative interactions are supported by specific molecular features within phase-separating proteins, such as multivalency and the presence of disordered domains that promote weak and transient interactions. However, these features also predispose phase-separating proteins to aberrant behavior. Indeed, evidence is emerging for a strong link between phase-separating proteins, MLOs, and age-related diseases. In this review, we discuss recent progress in understanding the formation, properties, and functions of MLOs. We pay special attention to the emerging link between MLOs and age-related diseases, and we explain how changes in the composition and physical properties of MLOs promote their conversion into an aberrant state. Furthermore, we discuss the key role of the protein quality control machinery in regulating the properties and functions of MLOs and thus in preventing age-related diseases.
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Affiliation(s)
- Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | - Serena Carra
- Department of Biomedical, Metabolic and Neural Science, University of Modena and Reggio Emilia, Center for Neuroscience and Neurotechnology, 41125 Modena, Italy.
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13
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Wojciechowska M, Sobczak K, Kozlowski P, Sedehizadeh S, Wojtkowiak-Szlachcic A, Czubak K, Markus R, Lusakowska A, Kaminska A, Brook JD. Quantitative Methods to Monitor RNA Biomarkers in Myotonic Dystrophy. Sci Rep 2018; 8:5885. [PMID: 29651162 PMCID: PMC5897446 DOI: 10.1038/s41598-018-24156-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/22/2018] [Indexed: 12/18/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are human neuromuscular disorders associated with mutations of simple repetitive sequences in affected genes. The abnormal expansion of CTG repeats in the 3'-UTR of the DMPK gene elicits DM1, whereas elongated CCTG repeats in intron 1 of ZNF9/CNBP triggers DM2. Pathogenesis of both disorders is manifested by nuclear retention of expanded repeat-containing RNAs and aberrant alternative splicing. The precise determination of absolute numbers of mutant RNA molecules is important for a better understanding of disease complexity and for accurate evaluation of the efficacy of therapeutic drugs. We present two quantitative methods, Multiplex Ligation-Dependent Probe Amplification and droplet digital PCR, for studying the mutant DMPK transcript (DMPKexpRNA) and the aberrant alternative splicing in DM1 and DM2 human tissues and cells. We demonstrate that in DM1, the DMPKexpRNA is detected in higher copy number than its normal counterpart. Moreover, the absolute number of the mutant transcript indicates its low abundance with only a few copies per cell in DM1 fibroblasts. Most importantly, in conjunction with fluorescence in-situ hybridization experiments, our results suggest that in DM1 fibroblasts, the vast majority of nuclear RNA foci consist of a few molecules of DMPKexpRNA.
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Affiliation(s)
- Marzena Wojciechowska
- University of Nottingham, Queen's Medical Centre, School of Life Sciences, Nottingham, NG7 2UH, United Kingdom. .,Institute of Bioorganic Chemistry, Polish Academy of Sciences, Department of Molecular Genetics, Poznan, 61-704, Poland.
| | - Krzysztof Sobczak
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Department of Gene Expression, Poznan, 60-614, Poland
| | - Piotr Kozlowski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Department of Molecular Genetics, Poznan, 61-704, Poland
| | - Saam Sedehizadeh
- University of Nottingham, Queen's Medical Centre, School of Life Sciences, Nottingham, NG7 2UH, United Kingdom
| | - Agnieszka Wojtkowiak-Szlachcic
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Department of Gene Expression, Poznan, 60-614, Poland
| | - Karol Czubak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Department of Molecular Genetics, Poznan, 61-704, Poland
| | - Robert Markus
- University of Nottingham, Queen's Medical Centre, School of Life Sciences, Nottingham, NG7 2UH, United Kingdom
| | - Anna Lusakowska
- Medical University of Warsaw, Department of Neurology, Warsaw, 02-097, Poland
| | - Anna Kaminska
- Medical University of Warsaw, Department of Neurology, Warsaw, 02-097, Poland
| | - J David Brook
- University of Nottingham, Queen's Medical Centre, School of Life Sciences, Nottingham, NG7 2UH, United Kingdom.
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14
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Thadke SA, Perera JDR, Hridya VM, Bhatt K, Shaikh AY, Hsieh WC, Chen M, Gayathri C, Gil RR, Rule GS, Mukherjee A, Thornton CA, Ly DH. Design of Bivalent Nucleic Acid Ligands for Recognition of RNA-Repeated Expansion Associated with Huntington's Disease. Biochemistry 2018; 57:2094-2108. [PMID: 29562132 PMCID: PMC6091552 DOI: 10.1021/acs.biochem.8b00062] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We report the development of a new class of nucleic acid ligands that is comprised of Janus bases and the MPγPNA backbone and is capable of binding rCAG repeats in a sequence-specific and selective manner via, inference, bivalent H-bonding interactions. Individually, the interactions between ligands and RNA are weak and transient. However, upon the installation of a C-terminal thioester and an N-terminal cystine and the reduction of disulfide bond, they undergo template-directed native chemical ligation to form concatenated oligomeric products that bind tightly to the RNA template. In the absence of an RNA target, they self-deactivate by undergoing an intramolecular reaction to form cyclic products, rendering them inactive for further binding. The work has implications for the design of ultrashort nucleic acid ligands for targeting rCAG-repeat expansion associated with Huntington's disease and a number of other related neuromuscular and neurodegenerative disorders.
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Affiliation(s)
- Shivaji A. Thadke
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Institute for Biomolecular Design and Discovery (IBD), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - J. Dinithi R. Perera
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Institute for Biomolecular Design and Discovery (IBD), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - V. M. Hridya
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra 411008, India
| | - Kirti Bhatt
- Department of Neurology, Box 645, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Ashif Y. Shaikh
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Institute for Biomolecular Design and Discovery (IBD), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Wei-Che Hsieh
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Institute for Biomolecular Design and Discovery (IBD), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Mengshen Chen
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Chakicherla Gayathri
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Roberto R. Gil
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Gordon S. Rule
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Arnab Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra 411008, India
| | - Charles A. Thornton
- Department of Neurology, Box 645, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Danith H. Ly
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Institute for Biomolecular Design and Discovery (IBD), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
- Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
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15
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Rousseaux MWC, Tschumperlin T, Lu HC, Lackey EP, Bondar VV, Wan YW, Tan Q, Adamski CJ, Friedrich J, Twaroski K, Chen W, Tolar J, Henzler C, Sharma A, Bajić A, Lin T, Duvick L, Liu Z, Sillitoe RV, Zoghbi HY, Orr HT. ATXN1-CIC Complex Is the Primary Driver of Cerebellar Pathology in Spinocerebellar Ataxia Type 1 through a Gain-of-Function Mechanism. Neuron 2018. [PMID: 29526553 DOI: 10.1016/j.neuron.2018.02.013] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Polyglutamine (polyQ) diseases are caused by expansion of translated CAG repeats in distinct genes leading to altered protein function. In spinocerebellar ataxia type 1 (SCA1), a gain of function of polyQ-expanded ataxin-1 (ATXN1) contributes to cerebellar pathology. The extent to which cerebellar toxicity depends on its cognate partner capicua (CIC), versus other interactors, remains unclear. It is also not established whether loss of the ATXN1-CIC complex in the cerebellum contributes to disease pathogenesis. In this study, we exclusively disrupt the ATXN1-CIC interaction in vivo and show that it is at the crux of cerebellar toxicity in SCA1. Importantly, loss of CIC in the cerebellum does not cause ataxia or Purkinje cell degeneration. Expression profiling of these gain- and loss-of-function models, coupled with data from iPSC-derived neurons from SCA1 patients, supports a mechanism in which gain of function of the ATXN1-CIC complex is the major driver of toxicity.
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Affiliation(s)
- Maxime W C Rousseaux
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tyler Tschumperlin
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Hsiang-Chih Lu
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Elizabeth P Lackey
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Vitaliy V Bondar
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ying-Wooi Wan
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Qiumin Tan
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Carolyn J Adamski
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jillian Friedrich
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kirk Twaroski
- Department of Pediatrics, Stem Cell Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Weili Chen
- Department of Pediatrics, Stem Cell Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jakub Tolar
- Department of Pediatrics, Stem Cell Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Christine Henzler
- RISS Bioinformatics, Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ajay Sharma
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Aleksandar Bajić
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tao Lin
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lisa Duvick
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhandong Liu
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pediatrics, Stem Cell Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Roy V Sillitoe
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Huda Y Zoghbi
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Houston, TX 77030, 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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16
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RAN translation at C9orf72-associated repeat expansions is selectively enhanced by the integrated stress response. Nat Commun 2017; 8:2005. [PMID: 29222490 PMCID: PMC5722904 DOI: 10.1038/s41467-017-02200-0] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 11/12/2017] [Indexed: 12/22/2022] Open
Abstract
Repeat-associated non-AUG (RAN) translation allows for unconventional initiation at disease-causing repeat expansions. As RAN translation contributes to pathogenesis in multiple neurodegenerative disorders, determining its mechanistic underpinnings may inform therapeutic development. Here we analyze RAN translation at G4C2 repeat expansions that cause C9orf72-associated amyotrophic lateral sclerosis and frontotemporal dementia (C9RAN) and at CGG repeats that cause fragile X-associated tremor/ataxia syndrome. We find that C9RAN translation initiates through a cap- and eIF4A-dependent mechanism that utilizes a CUG start codon. C9RAN and CGG RAN are both selectively enhanced by integrated stress response (ISR) activation. ISR-enhanced RAN translation requires an eIF2α phosphorylation-dependent alteration in start codon fidelity. In parallel, both CGG and G4C2 repeats trigger phosphorylated-eIF2α-dependent stress granule formation and global translational suppression. These findings support a model whereby repeat expansions elicit cellular stress conditions that favor RAN translation of toxic proteins, creating a potential feed-forward loop that contributes to neurodegeneration. A nucleotide repeat expansion in C9orf72 is a common genetic cause of neurodegenerative disorders. Here, the authors provide insight into the molecular mechanism by which this repeat undergoes Repeat-Associated Non-AUG (RAN) translation, implicating the integrated stress response and eIF2α phosphorylation.
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17
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Huang YS, Lu WH. Decoding hidden messages in neurons: insights from epitranscriptome-controlled and specialized ribosome-controlled translation. Curr Opin Neurobiol 2017; 48:64-70. [PMID: 29125978 DOI: 10.1016/j.conb.2017.10.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 10/11/2017] [Accepted: 10/17/2017] [Indexed: 11/26/2022]
Abstract
Activity-regulated protein synthesis, especially in the restricted synaptic domains, is critical to maintaining connections and communication between neurons. Accumulating evidence has linked dysregulated translation to various neurodevelopmental or neurodegenerative diseases. In the past 3 decades, after finding ribosomes and specific mRNAs localized around synapses, a significant amount of work has furthered our understanding of how the genetic sequences in mRNAs and their cognate RNA-binding proteins are coordinated to build up synaptic proteomes. Recent exciting findings of various RNA modifications, specialized ribosomes, and their regulatory roles in translation have led to emerging needs to unravel how synaptic ribosomes interpret these hidden codes to regulate molecular connectomes.
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Affiliation(s)
- Yi-Shuian Huang
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
| | - Wen-Hsin Lu
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan; Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei 11529, Taiwan
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18
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Rohilla KJ, Gagnon KT. RNA biology of disease-associated microsatellite repeat expansions. Acta Neuropathol Commun 2017; 5:63. [PMID: 28851463 PMCID: PMC5574247 DOI: 10.1186/s40478-017-0468-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/22/2017] [Indexed: 12/13/2022] Open
Abstract
Microsatellites, or simple tandem repeat sequences, occur naturally in the human genome and have important roles in genome evolution and function. However, the expansion of microsatellites is associated with over two dozen neurological diseases. A common denominator among the majority of these disorders is the expression of expanded tandem repeat-containing RNA, referred to as xtrRNA in this review, which can mediate molecular disease pathology in multiple ways. This review focuses on the potential impact that simple tandem repeat expansions can have on the biology and metabolism of RNA that contain them and underscores important gaps in understanding. Merging the molecular biology of repeat expansion disorders with the current understanding of RNA biology, including splicing, transcription, transport, turnover and translation, will help clarify mechanisms of disease and improve therapeutic development.
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19
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Ciesiolka A, Jazurek M, Drazkowska K, Krzyzosiak WJ. Structural Characteristics of Simple RNA Repeats Associated with Disease and their Deleterious Protein Interactions. Front Cell Neurosci 2017; 11:97. [PMID: 28442996 PMCID: PMC5387085 DOI: 10.3389/fncel.2017.00097] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/21/2017] [Indexed: 12/14/2022] Open
Abstract
Short Tandem Repeats (STRs) are frequent entities in many transcripts, however, in some cases, pathological events occur when a critical repeat length is reached. This phenomenon is observed in various neurological disorders, such as myotonic dystrophy type 1 (DM1), fragile X-associated tremor/ataxia syndrome, C9orf72-related amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD), and polyglutamine diseases, such as Huntington's disease (HD) and spinocerebellar ataxias (SCA). The pathological effects of these repeats are triggered by mutant RNA transcripts and/or encoded mutant proteins, which depend on the localization of the expanded repeats in non-coding or coding regions. A growing body of recent evidence revealed that the RNA structures formed by these mutant RNA repeat tracts exhibit toxic effects on cells. Therefore, in this review article, we present existing knowledge on the structural aspects of different RNA repeat tracts as revealed mainly using well-established biochemical and biophysical methods. Furthermore, in several cases, it was shown that these expanded RNA structures are potent traps for a variety of RNA-binding proteins and that the sequestration of these proteins from their normal intracellular environment causes alternative splicing aberration, inhibition of nuclear transport and export, or alteration of a microRNA biogenesis pathway. Therefore, in this review article, we also present the most studied examples of abnormal interactions that occur between mutant RNAs and their associated proteins.
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Affiliation(s)
- Adam Ciesiolka
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of SciencesPoznan, Poland
| | - Magdalena Jazurek
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of SciencesPoznan, Poland
| | - Karolina Drazkowska
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of SciencesPoznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of SciencesPoznan, Poland
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20
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Moens TG, Partridge L, Isaacs AM. Genetic models of C9orf72: what is toxic? Curr Opin Genet Dev 2017; 44:92-101. [PMID: 28364657 DOI: 10.1016/j.gde.2017.01.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 01/13/2017] [Accepted: 01/18/2017] [Indexed: 12/11/2022]
Abstract
A hexanucleotide repeat expansion in the gene C9orf72 is the most common genetic cause of both amyotrophic lateral sclerosis and frontotemporal dementia. Pathogenesis may occur either due to loss of function of the C9orf72 gene, or a toxic gain of function, via the production of repetitive sense and antisense RNA and/or repetitive dipeptide repeat proteins. Recently, mouse knockouts have suggested that a loss of function of C9orf72 alone is insufficient to lead to neurodegeneration, whilst overexpression of hexanucleotide DNA is sufficient in a wide range of model systems. Additionally, models have now been created to attempt to study the effects of repetitive RNA and dipeptide proteins in isolation and thus determine their relevance to disease.
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Affiliation(s)
- Thomas G Moens
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London WC1N 3BG, UK; Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Linda Partridge
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College London, London WC1E 6BT, UK; Max Planck Institute for Biology of Ageing, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - Adrian M Isaacs
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London WC1N 3BG, UK.
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21
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Błaszczyk L, Rypniewski W, Kiliszek A. Structures of RNA repeats associated with neurological diseases. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 8. [PMID: 28130835 DOI: 10.1002/wrna.1412] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 10/25/2016] [Accepted: 11/12/2016] [Indexed: 01/04/2023]
Abstract
All RNA molecules possess a 'propensity' to fold into complex secondary and tertiary structures. Although they are composed of only four types of nucleotides, they show an enormous structural richness which reflects their diverse functions in the cell. However, in some cases the folding of RNA can have deleterious consequences. Aberrantly expanded, repeated RNA sequences can exhibit gain-of-function abnormalities and become pathogenic, giving rise to many incurable neurological diseases. Most RNA repeats form long hairpin structures whose stem consists of noncanonical base pairs interspersed among Watson-Crick pairs. The expanded hairpins have an ability to sequester important proteins and form insoluble nuclear foci. The RNA pathology, common to many repeat disorders, has drawn attention to the structures of the RNA repeats. In this review, we summarize secondary structure probing and crystallographic studies of disease-related RNA repeat sequences. We discuss the unique structural features which can contribute to the pathogenic properties of the repeated runs. In addition, we present the newest reports concerning structural data linked to therapeutic approaches. WIREs RNA 2017, 8:e1412. doi: 10.1002/wrna.1412 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Leszek Błaszczyk
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Wojciech Rypniewski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Agnieszka Kiliszek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
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22
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Jaworska E, Kozlowska E, Switonski PM, Krzyzosiak WJ. Modeling simple repeat expansion diseases with iPSC technology. Cell Mol Life Sci 2016; 73:4085-100. [PMID: 27261369 PMCID: PMC11108530 DOI: 10.1007/s00018-016-2284-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 12/20/2022]
Abstract
A number of human genetic disorders, including Huntington's disease, myotonic dystrophy type 1, C9ORF72 form of amyotrophic lateral sclerosis and several spinocerebellar ataxias, are caused by the expansion of various microsatellite sequences in single implicated genes. The neurodegenerative and neuromuscular nature of the repeat expansion disorders considerably limits the access of researchers to appropriate cellular models of these diseases. This limitation, however, can be overcome by the application of induced pluripotent stem cell (iPSC) technology. In this paper, we review the current knowledge on the modeling of repeat expansion diseases with human iPSCs and iPSC-derived cells, focusing on the disease phenotypes recapitulated in these models. In subsequent sections, we provide basic practical knowledge regarding iPSC generation, characterization and differentiation into neurons. We also cover disease modeling in iPSCs, neuronal stem cells and specialized neuronal cultures. Furthermore, we also summarize the therapeutic potential of iPSC technology in repeat expansion diseases.
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Affiliation(s)
- Edyta Jaworska
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704, Poznan, Poland
| | - Emilia Kozlowska
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704, Poznan, Poland
| | - Pawel M Switonski
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704, Poznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704, Poznan, Poland.
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23
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Saffert P, Adamla F, Schieweck R, Atkins JF, Ignatova Z. An Expanded CAG Repeat in Huntingtin Causes +1 Frameshifting. J Biol Chem 2016; 291:18505-13. [PMID: 27382061 DOI: 10.1074/jbc.m116.744326] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Indexed: 01/08/2023] Open
Abstract
Maintenance of triplet decoding is crucial for the expression of functional protein because deviations either into the -1 or +1 reading frames are often non-functional. We report here that expression of huntingtin (Htt) exon 1 with expanded CAG repeats, implicated in Huntington pathology, undergoes a sporadic +1 frameshift to generate from the CAG repeat a trans-frame AGC repeat-encoded product. This +1 recoding is exclusively detected in pathological Htt variants, i.e. those with expanded repeats with more than 35 consecutive CAG codons. An atypical +1 shift site, UUC C at the 5' end of CAG repeats, which has some resemblance to the influenza A virus shift site, triggers the +1 frameshifting and is enhanced by the increased propensity of the expanded CAG repeats to form a stem-loop structure. The +1 trans-frame-encoded product can directly influence the aggregation of the parental Htt exon 1.
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Affiliation(s)
- Paul Saffert
- From the Institute of Biochemistry, University of Potsdam, 14467 Potsdam, Germany
| | - Frauke Adamla
- Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
| | - Rico Schieweck
- From the Institute of Biochemistry, University of Potsdam, 14467 Potsdam, Germany
| | - John F Atkins
- the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland, and the Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112
| | - Zoya Ignatova
- From the Institute of Biochemistry, University of Potsdam, 14467 Potsdam, Germany, Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany,
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24
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Li J, Sakata A, He H, Bai LP, Murata A, Dohno C, Nakatani K. Naphthyridine-Benzoazaquinolone: Evaluation of a Tricyclic System for the Binding to (CAG)nRepeat DNA and RNA. Chem Asian J 2016; 11:1971-81. [DOI: 10.1002/asia.201600527] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Jinxing Li
- Department of Regulatory Bioorganic Chemistry; The Institute of Scientific and Industrial Research; Osaka University; 8-1 Mihogaoka Ibaraki 567-0047 Japan
| | - Akihiro Sakata
- Department of Regulatory Bioorganic Chemistry; The Institute of Scientific and Industrial Research; Osaka University; 8-1 Mihogaoka Ibaraki 567-0047 Japan
| | - Hanping He
- Chemistry and Chemical Engineering College; Hubei University; Road Youyi 368, Wuchang, Wuhan Hubei 430062 China
| | - Li-Ping Bai
- State Key Laboratory of Quality Research in Chinese Medicine, and Macau Institute for Applied Research in Medicine and Health; Macau University of Science and Technology; Avenida Wai Long, Taipa Macau China
| | - Asako Murata
- Department of Regulatory Bioorganic Chemistry; The Institute of Scientific and Industrial Research; Osaka University; 8-1 Mihogaoka Ibaraki 567-0047 Japan
| | - Chikara Dohno
- Department of Regulatory Bioorganic Chemistry; The Institute of Scientific and Industrial Research; Osaka University; 8-1 Mihogaoka Ibaraki 567-0047 Japan
| | - Kazuhiko Nakatani
- Department of Regulatory Bioorganic Chemistry; The Institute of Scientific and Industrial Research; Osaka University; 8-1 Mihogaoka Ibaraki 567-0047 Japan
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25
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The expanding biology of the C9orf72 nucleotide repeat expansion in neurodegenerative disease. Nat Rev Neurosci 2016; 17:383-95. [PMID: 27150398 DOI: 10.1038/nrn.2016.38] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A nucleotide repeat expansion (NRE) within the chromosome 9 open reading frame 72 (C9orf72) gene was the first of this type of mutation to be linked to multiple neurological conditions, including amyotrophic lateral sclerosis and frontotemporal dementia. The pathogenic mechanisms through which the C9orf72 NRE contributes to these disorders include loss of C9orf72 function and gain-of-function mechanisms of C9orf72 driven by toxic RNA and protein species encoded by the NRE. These mechanisms have been linked to several cellular defects - including nucleocytoplasmic trafficking deficits and nuclear stress - that have been observed in both patients and animal models.
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26
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Green KM, Linsalata AE, Todd PK. RAN translation-What makes it run? Brain Res 2016; 1647:30-42. [PMID: 27060770 DOI: 10.1016/j.brainres.2016.04.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/24/2016] [Accepted: 04/01/2016] [Indexed: 12/14/2022]
Abstract
Nucleotide-repeat expansions underlie a heterogeneous group of neurodegenerative and neuromuscular disorders for which there are currently no effective therapies. Recently, it was discovered that such repetitive RNA motifs can support translation initiation in the absence of an AUG start codon across a wide variety of sequence contexts, and that the products of these atypical translation initiation events contribute to neuronal toxicity. This review examines what we currently know and do not know about repeat associated non-AUG (RAN) translation in the context of established canonical and non-canonical mechanisms of translation initiation. We highlight recent findings related to RAN translation in three repeat expansion disorders: CGG repeats in fragile X-associated tremor ataxia syndrome (FXTAS), GGGGCC repeats in C9orf72 associated amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) and CAG repeats in Huntington disease. These studies suggest that mechanistic differences may exist for RAN translation dependent on repeat type, repeat reading frame, and the surrounding sequence context, but that for at least some repeats, RAN translation retains a dependence on some of the canonical translational initiation machinery. This article is part of a Special Issue entitled SI:RNA Metabolism in Disease.
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Affiliation(s)
- Katelyn M Green
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States; Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Alexander E Linsalata
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States; Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Peter K Todd
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States; Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, United States; Veterans Affairs Medical Center, Ann Arbor, MI, United States.
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Quantitative analysis and clinico-pathological correlations of different dipeptide repeat protein pathologies in C9ORF72 mutation carriers. Acta Neuropathol 2015; 130:845-61. [PMID: 26374446 DOI: 10.1007/s00401-015-1476-2] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 09/01/2015] [Accepted: 09/03/2015] [Indexed: 12/13/2022]
Abstract
Hexanucleotide repeat expansion in C9ORF72 is the most common genetic cause of frontotemporal dementia and motor neuron disease. One consequence of the mutation is the formation of different potentially toxic polypeptides composed of dipeptide repeats (DPR) (poly-GA, -GP, -GR, -PA, -PR) generated by repeat-associated non-ATG (RAN) translation. While previous studies focusing on poly-GA pathology have failed to detect any clinico-pathological correlations in C9ORF72 mutation cases, recent data from animal and cell culture models suggested that it may be only specific DPR species that are toxic and only when accumulated in certain intracellular compartments. Therefore, we performed a systematic clinico-pathological correlative analysis with counting of actual numbers of distinct types of inclusion (neuronal cytoplasmic and intranuclear inclusions, dystrophic neurites) for each DPR protein in relevant brain regions (premotor cortex, lower motor neurons) in a cohort of 35 C9ORF72 mutation cases covering the clinical spectrum from those with pure MND, mixed FTD/MND and pure FTD. While each DPR protein pathology had a similar pattern of anatomical distribution, the total amount of inclusions for each DPR protein varied remarkably (poly-GA > GP > GR > PR/PA), indicating that RAN translation seems to be more effective from sense than from antisense transcripts. Importantly, with the exception of moderate associations for the amount of poly-GA-positive dystrophic neurites with degeneration in the frontal cortex and total burden of poly-GA pathology with disease onset, no relationship was identified for any other DPR protein pathology with degeneration or phenotype. Biochemical analysis revealed a close correlation between insoluble DPR protein species and numbers of visible inclusions, while we did not find any evidence for the presence of soluble DPR protein species. Thus, overall our findings strongly argue against a role of DPR protein aggregation as major and exclusive pathomechanism in C9ORF72 pathogenesis. However, this does not exclude that DPR protein formation might be essential in C9ORF72 pathogenesis in interplay with other consequences associated with the C9ORF72 repeat expansion.
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Nguyen L, Luu LM, Peng S, Serrano JF, Chan HYE, Zimmerman SC. Rationally designed small molecules that target both the DNA and RNA causing myotonic dystrophy type 1. J Am Chem Soc 2015; 137:14180-9. [PMID: 26473464 DOI: 10.1021/jacs.5b09266] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Single-agent, single-target therapeutic approaches are often limited by a complex disease pathobiology. We report rationally designed, multi-target agents for myotonic dystrophy type 1 (DM1). DM1 originates in an abnormal expansion of CTG repeats (CTG(exp)) in the DMPK gene. The resultant expanded CUG transcript (CUG(exp)) identified as a toxic agent sequesters important proteins, such as muscleblind-like proteins (MBNL), undergoes repeat-associated non-ATG (RAN) translation, and potentially causes microRNA dysregulation. We report rationally designed small molecules that target the DM1 pathobiology in vitro in three distinct ways by acting simultaneously as transcription inhibitors, by inhibiting aberrant protein binding to the toxic RNA, and by acting as RNase mimics to degrade the toxic RNA. In vitro, the agents are shown to (1) bind CTG(exp) and inhibit formation of the CUG(exp) transcript, (2) bind CUG(exp) and inhibit sequestration of MBNL1, and (3) cleave CUG(exp) in an RNase-like manner. The most potent compounds are capable of reducing the levels of CUG(exp) in DM1 model cells, and one reverses two separate CUG(exp)-induced phenotypes in a DM1 Drosophila model.
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Affiliation(s)
- Lien Nguyen
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Long M Luu
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Shaohong Peng
- Laboratory of Drosophila Research and School of Life Sciences, The Chinese University of Hong Kong , Shatin N.T., Hong Kong, SAR
| | - Julio F Serrano
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - H Y Edwin Chan
- Laboratory of Drosophila Research and School of Life Sciences, The Chinese University of Hong Kong , Shatin N.T., Hong Kong, SAR
| | - Steven C Zimmerman
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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Baranov PV, Atkins JF, Yordanova MM. Augmented genetic decoding: global, local and temporal alterations of decoding processes and codon meaning. Nat Rev Genet 2015; 16:517-29. [PMID: 26260261 DOI: 10.1038/nrg3963] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The non-universality of the genetic code is now widely appreciated. Codes differ between organisms, and certain genes are known to alter the decoding rules in a site-specific manner. Recently discovered examples of decoding plasticity are particularly spectacular. These examples include organisms and organelles with disruptions of triplet continuity during the translation of many genes, viruses that alter the entire genetic code of their hosts and organisms that adjust their genetic code in response to changing environments. In this Review, we outline various modes of alternative genetic decoding and expand existing terminology to accommodate recently discovered manifestations of this seemingly sophisticated phenomenon.
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Affiliation(s)
- Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Ireland
| | - John F Atkins
- 1] School of Biochemistry and Cell Biology, University College Cork, Ireland. [2] Department of Human Genetics, University of Utah, 15 N 2030 E Rm. 7410, Salt Lake City, Utah 84112-5330, USA
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Hukema RK, Buijsen RAM, Schonewille M, Raske C, Severijnen LAWFM, Nieuwenhuizen-Bakker I, Verhagen RFM, van Dessel L, Maas A, Charlet-Berguerand N, De Zeeuw CI, Hagerman PJ, Berman RF, Willemsen R. Reversibility of neuropathology and motor deficits in an inducible mouse model for FXTAS. Hum Mol Genet 2015; 24:4948-57. [PMID: 26060190 DOI: 10.1093/hmg/ddv216] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 06/04/2015] [Indexed: 01/18/2023] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder affecting carriers of the fragile X-premutation, who have an expanded CGG repeat in the 5'-UTR of the FMR1 gene. FXTAS is characterized by progressive development of intention tremor, ataxia, parkinsonism and neuropsychological problems. The disease is thought to be caused by a toxic RNA gain-of-function mechanism, and the major hallmark of the disease is ubiquitin-positive intranuclear inclusions in neurons and astrocytes. We have developed a new transgenic mouse model in which we can induce expression of an expanded repeat in the brain upon doxycycline (dox) exposure (i.e. Tet-On mice). This Tet-On model makes use of the PrP-rtTA driver and allows us to study disease progression and possibilities of reversibility. In these mice, 8 weeks of dox exposure was sufficient to induce the formation of ubiquitin-positive intranuclear inclusions, which also stain positive for the RAN translation product FMRpolyG. Formation of these inclusions is reversible after stopping expression of the expanded CGG RNA at an early developmental stage. Furthermore, we observed a deficit in the compensatory eye movements of mice with inclusions, a functional phenotype that could be reduced by stopping expression of the expanded CGG RNA early in the disease development. Taken together, this study shows, for the first time, the potential of disease reversibility and suggests that early intervention might be beneficial for FXTAS patients.
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Affiliation(s)
| | | | | | - Chris Raske
- Department of Biochemistry and Molecular Medicine and
| | | | | | | | | | - Alex Maas
- Department of Cell Biology, Erasmus MC, 3000 CA Rotterdam, The Netherlands
| | | | - Chris I De Zeeuw
- Department of Neuroscience The Netherlands Institute for Neuroscience, Amsterdam 1105 BA, The Netherlands
| | | | - Robert F Berman
- Department of Neurological Surgery, School of Medicine, University of California Davis, CA 95618, USA
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Michel AM, Ahern AM, Donohue CA, Baranov PV. GWIPS-viz as a tool for exploring ribosome profiling evidence supporting the synthesis of alternative proteoforms. Proteomics 2015; 15:2410-6. [PMID: 25736862 PMCID: PMC4832365 DOI: 10.1002/pmic.201400603] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/03/2015] [Accepted: 02/26/2015] [Indexed: 01/08/2023]
Abstract
The boundaries of protein coding sequences are more difficult to define at the 5′ end than at the 3′ end due to potential multiple translation initiation sites (TISs). Even in the presence of phylogenetic data, the use of sequence information only may not be sufficient for the accurate identification of TISs. Traditional proteomics approaches may also fail because the N‐termini of newly synthesized proteins are often processed. Thus ribosome profiling (ribo‐seq), producing a snapshot of the ribosome distribution across the entire transcriptome, is an attractive experimental technique for the purpose of TIS location exploration. The GWIPS‐viz (Genome Wide Information on Protein Synthesis visualized) browser (http://gwips.ucc.ie) provides free access to the genomic alignments of ribo‐seq data and corresponding mRNA‐seq data along with relevant annotation tracks. In this brief, we illustrate how GWIPS‐viz can be used to explore the ribosome occupancy at the 5′ ends of protein coding genes to assess the activity of AUG and non‐AUG TISs responsible for the synthesis of proteoforms with alternative or heterogeneous N‐termini. The presence of ribo‐seq tracks for various organisms allows for cross‐species comparison of orthologous genes and the availability of datasets from multiple laboratories permits the assessment of the technical reproducibility of the ribosome densities.
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Affiliation(s)
- Audrey M Michel
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Anna M Ahern
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Claire A Donohue
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
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The role of the immune system in triplet repeat expansion diseases. Mediators Inflamm 2015; 2015:873860. [PMID: 25873774 PMCID: PMC4385693 DOI: 10.1155/2015/873860] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 10/06/2014] [Accepted: 10/07/2014] [Indexed: 11/17/2022] Open
Abstract
Trinucleotide repeat expansion disorders (TREDs) are a group of dominantly inherited neurological diseases caused by the expansion of unstable repeats in specific regions of the associated genes. Expansion of CAG repeat tracts in translated regions of the respective genes results in polyglutamine- (polyQ-) rich proteins that form intracellular aggregates that affect numerous cellular activities. Recent evidence suggests the involvement of an RNA toxicity component in polyQ expansion disorders, thus increasing the complexity of the pathogenic processes. Neurodegeneration, accompanied by reactive gliosis and astrocytosis is the common feature of most TREDs, which may suggest involvement of inflammation in pathogenesis. Indeed, a number of immune response markers have been observed in the blood and CNS of patients and mouse models, and the activation of these markers was even observed in the premanifest stage of the disease. Although inflammation is not an initiating factor of TREDs, growing evidence indicates that inflammatory responses involving astrocytes, microglia, and the peripheral immune system may contribute to disease progression. Herein, we review the involvement of the immune system in the pathogenesis of triplet repeat expansion diseases, with particular emphasis on polyglutamine disorders. We also present various therapeutic approaches targeting the dysregulated inflammation pathways in these diseases.
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