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Oiwa K, Watanabe S, Onodera K, Iguchi Y, Kinoshita Y, Komine O, Sobue A, Okada Y, Katsuno M, Yamanaka K. Monomerization of TDP-43 is a key determinant for inducing TDP-43 pathology in amyotrophic lateral sclerosis. SCIENCE ADVANCES 2023; 9:eadf6895. [PMID: 37540751 PMCID: PMC10403219 DOI: 10.1126/sciadv.adf6895] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 07/05/2023] [Indexed: 08/06/2023]
Abstract
The cytoplasmic aggregation of TAR DNA binding protein-43 (TDP-43), also known as TDP-43 pathology, is the pathological hallmark of amyotrophic lateral sclerosis (ALS). However, the mechanism underlying TDP-43 cytoplasmic mislocalization and subsequent aggregation remains unclear. Here, we show that TDP-43 dimerization/multimerization is impaired in the postmortem brains and spinal cords of patients with sporadic ALS and that N-terminal dimerization-deficient TDP-43 consists of pathological inclusion bodies in ALS motor neurons. Expression of N-terminal dimerization-deficient mutant TDP-43 in Neuro2a cells and induced pluripotent stem cell-derived motor neurons recapitulates TDP-43 pathology, such as Nxf1-dependent cytoplasmic mislocalization and aggregate formation, which induces seeding effects. Furthermore, TDP-DiLuc, a bimolecular luminescence complementation reporter assay, could detect decreased N-terminal dimerization of TDP-43 before TDP-43 pathological changes caused by the transcription inhibition linked to aberrant RNA metabolism in ALS. These findings identified TDP-43 monomerization as a critical determinant inducing TDP-43 pathology in ALS.
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Affiliation(s)
- Kotaro Oiwa
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601, Japan
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
| | - Seiji Watanabe
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601, Japan
- Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
| | - Kazunari Onodera
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
- Department of Neural iPSC Research, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
- Department of Neurology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan
| | - Yohei Iguchi
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
| | - Yukako Kinoshita
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Okiru Komine
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601, Japan
- Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
| | - Akira Sobue
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601, Japan
- Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
- Medical Interactive Research and Academia Industry Collaboration Center, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan
| | - Yohei Okada
- Department of Neural iPSC Research, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
- Department of Neurology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
- Institute for Glyco-core Research (iGCORE), Nagoya University, Aichi, Japan
| | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601, Japan
- Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8560, Japan
- Institute for Glyco-core Research (iGCORE), Nagoya University, Aichi, Japan
- Center for One Medicine Innovative Translational Research (COMIT), Nagoya University, Nagoya, Aichi, Japan
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2
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Tamaki Y, Urushitani M. Molecular Dissection of TDP-43 as a Leading Cause of ALS/FTLD. Int J Mol Sci 2022; 23:ijms232012508. [PMID: 36293362 PMCID: PMC9604209 DOI: 10.3390/ijms232012508] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/13/2022] [Accepted: 10/17/2022] [Indexed: 11/16/2022] Open
Abstract
TAR DNA binding protein 43 (TDP-43) is a DNA/RNA binding protein involved in pivotal cellular functions, especially in RNA metabolism. Hyperphosphorylated and ubiquitinated TDP-43-positive neuronal cytoplasmic inclusions are identified in the brain and spinal cord in most cases of amyotrophic lateral sclerosis (ALS) and a substantial proportion of frontotemporal lobar degeneration (FTLD) cases. TDP-43 dysfunctions and cytoplasmic aggregation seem to be the central pathogenicity in ALS and FTLD. Therefore, unraveling both the physiological and pathological mechanisms of TDP-43 may enable the exploration of novel therapeutic strategies. This review highlights the current understanding of TDP-43 biology and pathology, describing the cellular processes involved in the pathogeneses of ALS and FTLD, such as post-translational modifications, RNA metabolism, liquid–liquid phase separation, proteolysis, and the potential prion-like propagation propensity of the TDP-43 inclusions.
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Affiliation(s)
- Yoshitaka Tamaki
- Department of Neurology, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Makoto Urushitani
- Department of Neurology, Shiga University of Medical Science, Otsu 520-2192, Japan
- Correspondence:
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3
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Kanekura K, Kuroda M. How can we interpret the relationship between liquid-liquid phase separation and amyotrophic lateral sclerosis? J Transl Med 2022; 102:912-918. [PMID: 36775420 DOI: 10.1038/s41374-022-00791-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/12/2022] [Indexed: 01/08/2023] Open
Abstract
One of the critical definitions of neurodegenerative diseases is the formation of insoluble intracellular inclusion body. These inclusions are found in various neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis (ALS), Huntington's disease, Parkinson's disease, and frontotemporal dementia (FTD). Each inclusion body contains disease-specific proteins and is also resistant to common detergent treatments. These aggregates are generally ubiquitinated and thus recognized as misfolded by the organism. They are observed in residual neurons at the affected sites in each disease, suggesting a contribution to disease pathogenesis. The molecular mechanisms for the formation of these inclusion bodies remain unclear. Some proteins, such as superoxide dismutase 1 (SOD1) mutant that causes familial ALS, are highly aggregative due to altered folding caused by point mutations. Still, the aggregates observed in neurodegenerative diseases contain wild-type proteins. In recent years, it has been reported that the proteins responsible for neurodegenerative diseases undergo liquid-liquid phase separation (LLPS). In particular, the ALS/FTD causative proteins such as TAR DNA-binding protein 43 kDa (TDP-43) and fused-in-sarcoma (FUS) undergo LLPS. LLPS increases the local concentration of these proteins, and these proteins eventually change their phase from liquid to solid (liquid-solid phase transition) due to abnormal folding during repetitive separation cycles into two phases and recovery to one phase. In addition to the inclusion body formation, sequestration of essential proteins into the LLPS droplets or changes in the LLPS status can directly impair neural functions and cause diseases. In this review, we will discuss the relationship between the LLPS observed in ALS causative proteins and the pathogenesis of the disease and outline potential therapeutic approaches.
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Affiliation(s)
- Kohsuke Kanekura
- Department of Molecular Pathology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan.
| | - Masahiko Kuroda
- Department of Molecular Pathology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan
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Dash BP, Freischmidt A, Weishaupt JH, Hermann A. Downstream Effects of Mutations in SOD1 and TARDBP Converge on Gene Expression Impairment in Patient-Derived Motor Neurons. Int J Mol Sci 2022; 23:ijms23179652. [PMID: 36077049 PMCID: PMC9456253 DOI: 10.3390/ijms23179652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a progressive and fatal neurodegenerative disease marked by death of motor neurons (MNs) present in the spinal cord, brain stem and motor cortex. Despite extensive research, the reason for neurodegeneration is still not understood. To generate novel hypotheses of putative underlying molecular mechanisms, we used human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs) from SOD1- and TARDBP (TDP-43 protein)-mutant-ALS patients and healthy controls to perform high-throughput RNA-sequencing (RNA-Seq). An integrated bioinformatics approach was employed to identify differentially expressed genes (DEGs) and key pathways underlying these familial forms of the disease (fALS). In TDP43-ALS, we found dysregulation of transcripts encoding components of the transcriptional machinery and transcripts involved in splicing regulation were particularly affected. In contrast, less is known about the role of SOD1 in RNA metabolism in motor neurons. Here, we found that many transcripts relevant for mitochondrial function were specifically altered in SOD1-ALS, indicating that transcriptional signatures and expression patterns can vary significantly depending on the causal gene that is mutated. Surprisingly, however, we identified a clear downregulation of genes involved in protein translation in SOD1-ALS suggesting that ALS-causing SOD1 mutations shift cellular RNA abundance profiles to cause neural dysfunction. Altogether, we provided here an extensive profiling of mRNA expression in two ALS models at the cellular level, corroborating the major role of RNA metabolism and gene expression as a common pathomechanism in ALS.
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Affiliation(s)
- Banaja P. Dash
- Translational Neurodegeneration Section “Albrecht-Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany
| | | | - Jochen H. Weishaupt
- Division of Neurodegeneration, Department of Neurology, Mannheim Center for Translational Neurosciences, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Andreas Hermann
- Translational Neurodegeneration Section “Albrecht-Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany
- Center for Transdisciplinary Neurosciences Rostock, University Medical Center Rostock, 18147 Rostock, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Rostock/Greifswald, 18147 Rostock, Germany
- Correspondence: ; Tel.: +49-(0)381-494-9541; Fax: +49-(0)381-494-9542
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Endogenous human retrovirus-K is not increased in the affected tissues of Japanese ALS patients. Neurosci Res 2022; 178:78-82. [PMID: 35122916 DOI: 10.1016/j.neures.2022.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/27/2022] [Accepted: 01/30/2022] [Indexed: 11/22/2022]
Abstract
Activation of human endogenous retrovirus-K (HERV-K) is one of the proposed risk factors for amyotrophic lateral sclerosis (ALS). The HERV-K envelope protein has been reported to show neurotoxicity, and development of therapy with reverse transcriptase inhibitors is being investigated. On the other hand, some reports have failed to show HERV-K activation in ALS. In this study, we analyzed the expression of HERV-K mRNA in the motor cortex and spinal cord of 15 Japanese patients with sporadic ALS and 19 controls using reverse transcriptase droplet digital PCR. This revealed no significant increase of HERV-K expression in ALS-affected tissues, suggesting that the association between ALS and HERV-K remains questionable.
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Mabin JW, Lewis PW, Brow DA, Dvinge H. Human spliceosomal snRNA sequence variants generate variant spliceosomes. RNA (NEW YORK, N.Y.) 2021; 27:1186-1203. [PMID: 34234030 PMCID: PMC8457000 DOI: 10.1261/rna.078768.121] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 06/29/2021] [Indexed: 06/02/2023]
Abstract
Human pre-mRNA splicing is primarily catalyzed by the major spliceosome, comprising five small nuclear ribonucleoprotein complexes, U1, U2, U4, U5, and U6 snRNPs, each of which contains the corresponding U-rich snRNA. These snRNAs are encoded by large gene families exhibiting significant sequence variation, but it remains unknown if most human snRNA genes are untranscribed pseudogenes or produce variant snRNAs with the potential to differentially influence splicing. Since gene duplication and variation are powerful mechanisms of evolutionary adaptation, we sought to address this knowledge gap by systematically profiling human U1, U2, U4, and U5 snRNA variant gene transcripts. We identified 55 transcripts that are detectably expressed in human cells, 38 of which incorporate into snRNPs and spliceosomes in 293T cells. All U1 snRNA variants are more than 1000-fold less abundant in spliceosomes than the canonical U1, whereas at least 1% of spliceosomes contain a variant of U2 or U4. In contrast, eight U5 snRNA sequence variants occupy spliceosomes at levels of 1% to 46%. Furthermore, snRNA variants display distinct expression patterns across five human cell lines and adult and fetal tissues. Different RNA degradation rates contribute to the diverse steady state levels of snRNA variants. Our findings suggest that variant spliceosomes containing noncanonical snRNAs may contribute to different tissue- and cell-type-specific alternative splicing patterns.
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Affiliation(s)
- Justin W Mabin
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
| | - Peter W Lewis
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
| | - David A Brow
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
| | - Heidi Dvinge
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
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Nishimoto Y, Nakagawa S, Okano H. NEAT1 lncRNA and amyotrophic lateral sclerosis. Neurochem Int 2021; 150:105175. [PMID: 34481908 DOI: 10.1016/j.neuint.2021.105175] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/14/2021] [Accepted: 08/30/2021] [Indexed: 12/15/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a representative neurological disease that is known to devastate entire motor neurons within a period of just a few years. Discoveries of the specific pathologies of relevant RNA-binding proteins, including TAR DNA-binding protein-43 (TDP-43) and fused in sarcoma/translocated in liposarcoma (FUS/TLS), and the causative genes of both familial and sporadic ALS have provided crucial information that could lead to a cure. In recent ALS research the GGGGCC-repeat expansion in the C9orf72 gene was identified as one of the most important pathological findings, suggesting the significance of both nuclear dysfunction due to dipeptide repeat proteins (DPRs) and RNA toxicity (such as pathological alterations of non-coding RNAs). In research on model animals carrying ALS-related molecules, the determination of whether a factor is protective or toxic has been controversial. Herein, we review the findings regarding NEAT1 RNA and C9orf72 GGGGCC repeats associated with ALS, from the viewpoint of conversion from the protective stage in the nucleus in early-phase ALS to late-phase induction of cell death. This review will provide insights for the development of RNA effectors as novel ALS treatments.
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Affiliation(s)
- Yoshinori Nishimoto
- Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, Japan; Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, Japan.
| | - Shinichi Nakagawa
- RNA Biology Laboratory, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, Japan.
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8
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Yang H, Beutler B, Zhang D. Emerging roles of spliceosome in cancer and immunity. Protein Cell 2021; 13:559-579. [PMID: 34196950 PMCID: PMC9232692 DOI: 10.1007/s13238-021-00856-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 05/08/2021] [Indexed: 12/19/2022] Open
Abstract
Precursor messenger RNA (pre-mRNA) splicing is catalyzed by an intricate ribonucleoprotein complex called the spliceosome. Although the spliceosome is considered to be general cell “housekeeping” machinery, mutations in core components of the spliceosome frequently correlate with cell- or tissue-specific phenotypes and diseases. In this review, we expound the links between spliceosome mutations, aberrant splicing, and human cancers. Remarkably, spliceosome-targeted therapies (STTs) have become efficient anti-cancer strategies for cancer patients with splicing defects. We also highlight the links between spliceosome and immune signaling. Recent studies have shown that some spliceosome gene mutations can result in immune dysregulation and notable phenotypes due to mis-splicing of immune-related genes. Furthermore, several core spliceosome components harbor splicing-independent immune functions within the cell, expanding the functional repertoire of these diverse proteins.
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Affiliation(s)
- Hui Yang
- Department of Neurosurgery, Huashan Hospital, Shanghai Key laboratory of Brain Function Restoration and Neural Regeneration, MOE Frontiers Center for Brain Science, Institute for Translational Brain Research, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Bruce Beutler
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Duanwu Zhang
- Children's Hospital of Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
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9
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El Marabti E, Abdel-Wahab O. Therapeutic Modulation of RNA Splicing in Malignant and Non-Malignant Disease. Trends Mol Med 2021; 27:643-659. [PMID: 33994320 DOI: 10.1016/j.molmed.2021.04.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/11/2021] [Accepted: 04/13/2021] [Indexed: 01/24/2023]
Abstract
RNA splicing is the enzymatic process by which non-protein coding sequences are removed from RNA to produce mature protein-coding mRNA. Splicing is thereby a major mediator of proteome diversity as well as a dynamic regulator of gene expression. Genetic alterations disrupting splicing of individual genes or altering the function of splicing factors contribute to a wide range of human genetic diseases as well as cancer. These observations have resulted in the development of therapies based on oligonucleotides that bind to RNA sequences and modulate splicing for therapeutic benefit. In parallel, small molecules that bind to splicing factors to alter their function or modify RNA processing of individual transcripts are being pursued for monogenic disorders as well as for cancer.
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Affiliation(s)
- Ettaib El Marabti
- Clinical Transplant Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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10
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Jutzi D, Campagne S, Schmidt R, Reber S, Mechtersheimer J, Gypas F, Schweingruber C, Colombo M, von Schroetter C, Loughlin FE, Devoy A, Hedlund E, Zavolan M, Allain FHT, Ruepp MD. Aberrant interaction of FUS with the U1 snRNA provides a molecular mechanism of FUS induced amyotrophic lateral sclerosis. Nat Commun 2020; 11:6341. [PMID: 33311468 PMCID: PMC7733473 DOI: 10.1038/s41467-020-20191-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 11/13/2020] [Indexed: 12/13/2022] Open
Abstract
Mutations in the RNA-binding protein Fused in Sarcoma (FUS) cause early-onset amyotrophic lateral sclerosis (ALS). However, a detailed understanding of central RNA targets of FUS and their implications for disease remain elusive. Here, we use a unique blend of crosslinking and immunoprecipitation (CLIP) and NMR spectroscopy to identify and characterise physiological and pathological RNA targets of FUS. We find that U1 snRNA is the primary RNA target of FUS via its interaction with stem-loop 3 and provide atomic details of this RNA-mediated mode of interaction with the U1 snRNP. Furthermore, we show that ALS-associated FUS aberrantly contacts U1 snRNA at the Sm site with its zinc finger and traps snRNP biogenesis intermediates in human and murine motor neurons. Altogether, we present molecular insights into a FUS toxic gain-of-function involving direct and aberrant RNA-binding and strengthen the link between two motor neuron diseases, ALS and spinal muscular atrophy (SMA).
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Affiliation(s)
- Daniel Jutzi
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Sébastien Campagne
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, CH-8093, Zürich, Switzerland
| | - Ralf Schmidt
- Computational and Systems Biology, Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Stefan Reber
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Jonas Mechtersheimer
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Foivos Gypas
- Computational and Systems Biology, Biozentrum, University of Basel, CH-4056, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, CH-4058, Basel, Switzerland
| | | | - Martino Colombo
- Celgene Institute of Translational Research (CITRE), 41092, Seville, Spain
| | - Christine von Schroetter
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, CH-8093, Zürich, Switzerland
| | - Fionna E Loughlin
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, CH-8093, Zürich, Switzerland
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC, 3800, Australia
| | - Anny Devoy
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Eva Hedlund
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Mihaela Zavolan
- Computational and Systems Biology, Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Frédéric H-T Allain
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, CH-8093, Zürich, Switzerland.
| | - Marc-David Ruepp
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK.
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11
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de Boer EMJ, Orie VK, Williams T, Baker MR, De Oliveira HM, Polvikoski T, Silsby M, Menon P, van den Bos M, Halliday GM, van den Berg LH, Van Den Bosch L, van Damme P, Kiernan MC, van Es MA, Vucic S. TDP-43 proteinopathies: a new wave of neurodegenerative diseases. J Neurol Neurosurg Psychiatry 2020; 92:jnnp-2020-322983. [PMID: 33177049 PMCID: PMC7803890 DOI: 10.1136/jnnp-2020-322983] [Citation(s) in RCA: 151] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/28/2020] [Accepted: 09/13/2020] [Indexed: 12/31/2022]
Abstract
Inclusions of pathogenic deposits containing TAR DNA-binding protein 43 (TDP-43) are evident in the brain and spinal cord of patients that present across a spectrum of neurodegenerative diseases. For instance, the majority of patients with sporadic amyotrophic lateral sclerosis (up to 97%) and a substantial proportion of patients with frontotemporal lobar degeneration (~45%) exhibit TDP-43 positive neuronal inclusions, suggesting a role for this protein in disease pathogenesis. In addition, TDP-43 inclusions are evident in familial ALS phenotypes linked to multiple gene mutations including the TDP-43 gene coding (TARDBP) and unrelated genes (eg, C9orf72). While TDP-43 is an essential RNA/DNA binding protein critical for RNA-related metabolism, determining the pathophysiological mechanisms through which TDP-43 mediates neurodegeneration appears complex, and unravelling these molecular processes seems critical for the development of effective therapies. This review highlights the key physiological functions of the TDP-43 protein, while considering an expanding spectrum of neurodegenerative diseases associated with pathogenic TDP-43 deposition, and dissecting key molecular pathways through which TDP-43 may mediate neurodegeneration.
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Affiliation(s)
- Eva Maria Johanna de Boer
- Department of Neurology, Brain Centre Rudolf Magnus, Universitair Medisch Centrum Utrecht, Utrecht, The Netherlands
| | - Viyanti K Orie
- Department of Neurology, Brain Centre Rudolf Magnus, Universitair Medisch Centrum Utrecht, Utrecht, The Netherlands
| | - Timothy Williams
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Mark R Baker
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- Department of Clinical Neurophysiology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Hugo M De Oliveira
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Tuomo Polvikoski
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- Department of Neuropathology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Matthew Silsby
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Parvathi Menon
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Mehdi van den Bos
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Glenda M Halliday
- Brain and Mind Center, University of Sydney, Sydney, New South Wales, Australia
- Department of Neurology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - Leonard H van den Berg
- Department of Neurology, Brain Centre Rudolf Magnus, Universitair Medisch Centrum Utrecht, Utrecht, The Netherlands
| | - Ludo Van Den Bosch
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute (LBI), University of Leuven, Leuven, Belgium
- Center for Brain & Disease Research, Laboratory of Neurobiology, VIB, Leuven, Belgium
| | - Philip van Damme
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute (LBI), University of Leuven, Leuven, Belgium
- Center for Brain & Disease Research, Laboratory of Neurobiology, VIB, Leuven, Belgium
- Department of Neurology, University Hospital Leuven, Leuven, Belgium
| | - Matthew C Kiernan
- Brain and Mind Center, University of Sydney, Sydney, New South Wales, Australia
- Department of Neurology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - Michael A van Es
- Department of Neurology, Brain Centre Rudolf Magnus, Universitair Medisch Centrum Utrecht, Utrecht, The Netherlands
| | - Steve Vucic
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
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12
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Osman EY, Van Alstyne M, Yen PF, Lotti F, Feng Z, Ling KK, Ko CP, Pellizzoni L, Lorson CL. Minor snRNA gene delivery improves the loss of proprioceptive synapses on SMA motor neurons. JCI Insight 2020; 5:130574. [PMID: 32516136 DOI: 10.1172/jci.insight.130574] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 05/13/2020] [Indexed: 12/17/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an inherited neuromuscular disorder caused by reduced expression of the survival motor neuron (SMN) protein. SMN has key functions in multiple RNA pathways, including the biogenesis of small nuclear ribonucleoproteins that are essential components of both major (U2-dependent) and minor (U12-dependent) spliceosomes. Here we investigated the specific contribution of U12 splicing dysfunction to SMA pathology through selective restoration of this RNA pathway in mouse models of varying phenotypic severity. We show that virus-mediated delivery of minor snRNA genes specifically improves select U12 splicing defects induced by SMN deficiency in cultured mammalian cells, as well as in the spinal cord and dorsal root ganglia of SMA mice without increasing SMN expression. This approach resulted in a moderate amelioration of several parameters of the disease phenotype in SMA mice, including survival, weight gain, and motor function. Importantly, minor snRNA gene delivery improved aberrant splicing of the U12 intron-containing gene Stasimon and rescued the severe loss of proprioceptive sensory synapses on SMA motor neurons, which are early signatures of motor circuit dysfunction in mouse models. Taken together, these findings establish the direct contribution of U12 splicing dysfunction to synaptic deafferentation and motor circuit pathology in SMA.
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Affiliation(s)
- Erkan Y Osman
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Meaghan Van Alstyne
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Pei-Fen Yen
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Francesco Lotti
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Zhihua Feng
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Karen Ky Ling
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Chien-Ping Ko
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Christian L Lorson
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
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13
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Sapaly D, Delers P, Coridon J, Salman B, Letourneur F, Dumont F, Lefebvre S. The Small-Molecule Flunarizine in Spinal Muscular Atrophy Patient Fibroblasts Impacts on the Gemin Components of the SMN Complex and TDP43, an RNA-Binding Protein Relevant to Motor Neuron Diseases. Front Mol Biosci 2020; 7:55. [PMID: 32363199 PMCID: PMC7181958 DOI: 10.3389/fmolb.2020.00055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/18/2020] [Indexed: 01/01/2023] Open
Abstract
The motor neurodegenerative disease spinal muscular atrophy (SMA) is caused by alterations of the survival motor neuron 1 (SMN1) gene involved in RNA metabolism. Although the disease mechanisms are not completely elucidated, SMN protein deficiency leads to abnormal small nuclear ribonucleoproteins (snRNPs) assembly responsible for widespread splicing defects. SMN protein localizes in nuclear bodies that are lost in SMA and adult onset amyotrophic lateral sclerosis (ALS) patient cells harboring TDP-43 or FUS/TLS mutations. We previously reported that flunarizine recruits SMN into nuclear bodies and improves the phenotype of an SMA mouse model. However, the precise mode of action remains elusive. Here, a marked reduction of the integral components of the SMN complex is observed in severe SMA patient fibroblast cells. We show that flunarizine increases the protein levels of a subset of components of the SMN-Gemins complex, Gemins2-4, and markedly reduces the RNA and protein levels of the pro-oxydant thioredoxin-interacting protein (TXNIP) encoded by an mRNA target of Gemin5. We further show that SMN deficiency causes a dissociation of the localization of the SMN complex components from the same nuclear bodies. The accumulation of TDP-43 in SMN-positive nuclear bodies is also perturbed in SMA cells. Notably, TDP-43 is found to co-localize with SMN in nuclear bodies of flunarizine-treated SMA cells. Our findings indicate that flunarizine reverses cellular changes caused by SMN deficiency in SMA cells and further support the view of a common pathway in RNA metabolism underlying infantile and adult motor neuron diseases.
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Affiliation(s)
- Delphine Sapaly
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, Campus Saint-Germain-des-Prés, Université de Paris, Paris, France
| | - Perrine Delers
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, Campus Saint-Germain-des-Prés, Université de Paris, Paris, France
| | - Jennifer Coridon
- BioMedTech Facilities INSERM US36 - CNRS UMS 2009, Campus Saint-Germain-des-Prés, Université de Paris, Paris, France
| | - Badih Salman
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, Campus Saint-Germain-des-Prés, Université de Paris, Paris, France
| | | | - Florent Dumont
- Genom'ic Platform, INSERM U1016, Institut Cochin, Paris, France
| | - Suzie Lefebvre
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, Campus Saint-Germain-des-Prés, Université de Paris, Paris, France
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14
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Picchiarelli G, Dupuis L. Role of RNA Binding Proteins with prion-like domains in muscle and neuromuscular diseases. Cell Stress 2020; 4:76-91. [PMID: 32292882 PMCID: PMC7146060 DOI: 10.15698/cst2020.04.217] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A number of neuromuscular and muscular diseases, including amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA) and several myopathies, are associated to mutations in related RNA-binding proteins (RBPs), including TDP-43, FUS, MATR3 or hnRNPA1/B2. These proteins harbor similar modular primary sequence with RNA binding motifs and low complexity domains, that enables them to phase separate and create liquid microdomains. These RBPs have been shown to critically regulate multiple events of RNA lifecycle, including transcriptional events, splicing and RNA trafficking and sequestration. Here, we review the roles of these disease-related RBPs in muscle and motor neurons, and how their dysfunction in these cell types might contribute to disease.
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Affiliation(s)
- Gina Picchiarelli
- Université de Strasbourg, INSERM, Mécanismes Centraux et Périphériques de la Neurodégénérescence, UMR_S 1118, Strasbourg, France
| | - Luc Dupuis
- Université de Strasbourg, INSERM, Mécanismes Centraux et Périphériques de la Neurodégénérescence, UMR_S 1118, Strasbourg, France
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15
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Bridging biophysics and neurology: aberrant phase transitions in neurodegenerative disease. Nat Rev Neurol 2020; 15:272-286. [PMID: 30890779 DOI: 10.1038/s41582-019-0157-5] [Citation(s) in RCA: 123] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Biomolecular condensation arising through phase transitions has emerged as an essential organizational strategy that governs many aspects of cell biology. In particular, the role of phase transitions in the assembly of large, complex ribonucleoprotein (RNP) granules has become appreciated as an important regulator of RNA metabolism. In parallel, genetic, histopathological and cell and molecular studies have provided evidence that disturbance of phase transitions is an important driver of neurological diseases, notably amyotrophic lateral sclerosis (ALS), but most likely also other diseases. Indeed, our growing knowledge of the biophysics underlying biological phase transitions suggests that this process offers a unifying mechanism to explain the numerous and diverse disturbances in RNA metabolism that have been observed in ALS and some related diseases - specifically, that these diseases are driven by disturbances in the material properties of RNP granules. Here, we review the evidence for this hypothesis, emphasizing the reciprocal roles in which disease-related protein and disease-related RNA can lead to disturbances in the material properties of RNP granules and consequent pathogenesis. Additionally, we review evidence that implicates aberrant phase transitions as a contributing factor to a larger set of neurodegenerative diseases, including frontotemporal dementia, certain repeat expansion diseases and Alzheimer disease.
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16
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Watanabe S, Oiwa K, Murata Y, Komine O, Sobue A, Endo F, Takahashi E, Yamanaka K. ALS-linked TDP-43 M337V knock-in mice exhibit splicing deregulation without neurodegeneration. Mol Brain 2020; 13:8. [PMID: 31959210 PMCID: PMC6971932 DOI: 10.1186/s13041-020-0550-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 01/12/2020] [Indexed: 11/10/2022] Open
Abstract
Abnormal accumulation of TAR DNA-binding protein 43 (TDP-43), a DNA/RNA binding protein, is a pathological signature of amyotrophic lateral sclerosis (ALS). Missense mutations in the TARDBP gene are also found in inherited and sporadic ALS, indicating that dysfunction in TDP-43 is causative for ALS. To model TDP-43-linked ALS in rodents, we generated TDP-43 knock-in mice with inherited ALS patient-derived TDP-43M337V mutation. Homozygous TDP-43M337V mice developed normally without exhibiting detectable motor dysfunction and neurodegeneration. However, splicing of mRNAs regulated by TDP-43 was deregulated in the spinal cords of TDP-43M337V mice. Together with the recently reported TDP-43 knock-in mice with ALS-linked mutations, our finding indicates that ALS patient-derived mutations in the TARDBP gene at a carboxyl-terminal domain of TDP-43 may cause a gain of splicing function by TDP-43, however, were insufficient to induce robust neurodegeneration in mice.
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Affiliation(s)
- Seiji Watanabe
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan.,Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8550, Japan
| | - Kotaro Oiwa
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan.,Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya University, Nagoya, Aichi, 466-8550, Japan
| | - Yuri Murata
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Okiru Komine
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan.,Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8550, Japan
| | - Akira Sobue
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan.,Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8550, Japan
| | - Fumito Endo
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan.,Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8550, Japan
| | - Eiki Takahashi
- Support Unit for Animal Resources Development, Research Resource Division, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan
| | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan. .,Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8550, Japan.
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17
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Kasahara S, Ishihara T, Koike Y, Sugai A, Onodera O. [Molecular mechanism of amyotrophic lateral sclerosis (ALS) from the viewpoint of the formation and degeneration of transactive response DNA-binding protein 43 kDa (TDP-43) inclusions]. Rinsho Shinkeigaku 2020; 60:109-116. [PMID: 31956195 DOI: 10.5692/clinicalneurol.cn-001362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sporadic amyotrophic lateral sclerosis (SALS) and many cases of familial ALS (FALS) demonstrate cytoplasmic transactive response DNA-binding protein 43 kDa (TDP-43)-positive inclusion bodies. Thus, TDP-43 plays a vital role in ALS pathogenesis. Functional analysis of the ALS causative genes advanced the elucidation of the mechanism associated with the formation and degradation of TDP-43 aggregates. Stress granules, which are non-membranous organelles, are attracting attention as sites of aggregate formation, with involvement of FUS and C9orf72. Concurrently, ALS causative genes related to the ubiquitin-proteasome and autophagy systems, which are aggregate degradation mechanisms, have also been reported. Therefore, therapeutic research based on the molecular pathology common to SALS and FALS has been advanced.
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Affiliation(s)
- Sou Kasahara
- Department of Neurology, Brain Research Institute, Niigata University
| | - Tomohiko Ishihara
- Department of Neurology, Brain Research Institute, Niigata University
| | - Yuka Koike
- Department of Neurology, Brain Research Institute, Niigata University
| | - Akihiro Sugai
- Department of Neurology, Brain Research Institute, Niigata University
| | - Osamu Onodera
- Department of Neurology, Brain Research Institute, Niigata University
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18
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Splicing Players Are Differently Expressed in Sporadic Amyotrophic Lateral Sclerosis Molecular Clusters and Brain Regions. Cells 2020; 9:cells9010159. [PMID: 31936368 PMCID: PMC7017305 DOI: 10.3390/cells9010159] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/23/2019] [Accepted: 01/04/2020] [Indexed: 12/12/2022] Open
Abstract
Splicing is a tightly orchestrated process by which the brain produces protein diversity over time and space. While this process specializes and diversifies neurons, its deregulation may be responsible for their selective degeneration. In amyotrophic lateral sclerosis (ALS), splicing defects have been investigated at the singular gene level without considering the higher-order level, involving the entire splicing machinery. In this study, we analyzed the complete spectrum (396) of genes encoding splicing factors in the motor cortex (41) and spinal cord (40) samples from control and sporadic ALS (SALS) patients. A substantial number of genes (184) displayed significant expression changes in tissue types or disease states, were implicated in distinct splicing complexes and showed different topological hierarchical roles based on protein–protein interactions. The deregulation of one of these splicing factors has a central topological role, i.e., the transcription factor YBX1, which might also have an impact on stress granule formation, a pathological marker associated with ALS.
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19
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Cacciottolo R, Ciantar J, Lanfranco M, Borg RM, Vassallo N, Bordonné R, Cauchi RJ. SMN complex member Gemin3 self-interacts and has a functional relationship with ALS-linked proteins TDP-43, FUS and Sod1. Sci Rep 2019; 9:18666. [PMID: 31822699 PMCID: PMC6904755 DOI: 10.1038/s41598-019-53508-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 10/29/2019] [Indexed: 02/07/2023] Open
Abstract
The predominant motor neuron disease in infants and adults is spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS), respectively. SMA is caused by insufficient levels of the Survival Motor Neuron (SMN) protein, which operates as part of the multiprotein SMN complex that includes the DEAD-box RNA helicase Gemin3/DDX20/DP103. C9orf72, SOD1, TDP-43 and FUS are ranked as the four major genes causing familial ALS. Accumulating evidence has revealed a surprising molecular overlap between SMA and ALS. Here, we ask the question of whether Drosophila can also be exploited to study shared pathogenic pathways. Focusing on motor behaviour, muscle mass and survival, we show that disruption of either TBPH/TDP-43 or Caz/FUS enhance defects associated with Gemin3 loss-of-function. Gemin3-associated neuromuscular junction overgrowth was however suppressed. Sod1 depletion had a modifying effect in late adulthood. We also show that Gemin3 self-interacts and Gem3ΔN, a helicase domain deletion mutant, retains the ability to interact with its wild-type counterpart. Importantly, mutant:wild-type dimers are favoured more than wild-type:wild-type dimers. In addition to reinforcing the link between SMA and ALS, further exploration of mechanistic overlaps is now possible in a genetically tractable model organism. Notably, Gemin3 can be elevated to a candidate for modifying motor neuron degeneration.
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Affiliation(s)
- Rebecca Cacciottolo
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR 5535, Université de Montpellier, Montpellier, France.,Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Joanna Ciantar
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Maia Lanfranco
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR 5535, Université de Montpellier, Montpellier, France.,Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Rebecca M Borg
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR 5535, Université de Montpellier, Montpellier, France.,Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Neville Vassallo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Rémy Bordonné
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR 5535, Université de Montpellier, Montpellier, France
| | - Ruben J Cauchi
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta. .,Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta.
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20
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Nussbacher JK, Tabet R, Yeo GW, Lagier-Tourenne C. Disruption of RNA Metabolism in Neurological Diseases and Emerging Therapeutic Interventions. Neuron 2019; 102:294-320. [PMID: 30998900 DOI: 10.1016/j.neuron.2019.03.014] [Citation(s) in RCA: 158] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 01/24/2019] [Accepted: 03/12/2019] [Indexed: 02/06/2023]
Abstract
RNA binding proteins are critical to the maintenance of the transcriptome via controlled regulation of RNA processing and transport. Alterations of these proteins impact multiple steps of the RNA life cycle resulting in various molecular phenotypes such as aberrant RNA splicing, transport, and stability. Disruption of RNA binding proteins and widespread RNA processing defects are increasingly recognized as critical determinants of neurological diseases. Here, we describe distinct mechanisms by which the homeostasis of RNA binding proteins is compromised in neurological disorders through their reduced expression level, increased propensity to aggregate or sequestration by abnormal RNAs. These mechanisms all converge toward altered neuronal function highlighting the susceptibility of neurons to deleterious changes in RNA expression and the central role of RNA binding proteins in preserving neuronal integrity. Emerging therapeutic approaches to mitigate or reverse alterations of RNA binding proteins in neurological diseases are discussed.
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Affiliation(s)
- Julia K Nussbacher
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA, USA
| | - Ricardos Tabet
- Department of Neurology, The Sean M. Healey and AMG Center for ALS at Mass General, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; Broad Institute of Harvard University and MIT, Cambridge, MA 02142, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA, USA.
| | - Clotilde Lagier-Tourenne
- Department of Neurology, The Sean M. Healey and AMG Center for ALS at Mass General, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; Broad Institute of Harvard University and MIT, Cambridge, MA 02142, USA.
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21
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Dvinge H, Guenthoer J, Porter PL, Bradley RK. RNA components of the spliceosome regulate tissue- and cancer-specific alternative splicing. Genome Res 2019; 29:1591-1604. [PMID: 31434678 PMCID: PMC6771400 DOI: 10.1101/gr.246678.118] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 08/15/2019] [Indexed: 01/08/2023]
Abstract
Alternative splicing of pre-mRNAs plays a pivotal role during the establishment and maintenance of human cell types. Characterizing the trans-acting regulatory proteins that control alternative splicing has therefore been the focus of much research. Recent work has established that even core protein components of the spliceosome, which are required for splicing to proceed, can nonetheless contribute to splicing regulation by modulating splice site choice. We here show that the RNA components of the spliceosome likewise influence alternative splicing decisions. Although these small nuclear RNAs (snRNAs), termed U1, U2, U4, U5, and U6 snRNA, are present in equal stoichiometry within the spliceosome, we found that their relative levels vary by an order of magnitude during development, across tissues, and across cancer samples. Physiologically relevant perturbation of individual snRNAs drove widespread gene-specific differences in alternative splicing but not transcriptome-wide splicing failure. Genes that were particularly sensitive to variations in snRNA abundance in a breast cancer cell line model were likewise preferentially misspliced within a clinically diverse cohort of invasive breast ductal carcinomas. As aberrant mRNA splicing is prevalent in many cancers, we propose that a full understanding of such dysregulated pre-mRNA processing requires study of snRNAs, as well as protein splicing factors. Together, our data show that the RNA components of the spliceosome are not merely basal factors, as has long been assumed. Instead, these noncoding RNAs constitute a previously uncharacterized layer of regulation of alternative splicing, and contribute to the establishment of global splicing programs in both healthy and malignant cells.
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Affiliation(s)
- Heidi Dvinge
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.,Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Jamie Guenthoer
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Peggy L Porter
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Robert K Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.,Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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22
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Perrone B, La Cognata V, Sprovieri T, Ungaro C, Conforti FL, Andò S, Cavallaro S. Alternative Splicing of ALS Genes: Misregulation and Potential Therapies. Cell Mol Neurobiol 2019; 40:1-14. [PMID: 31385134 DOI: 10.1007/s10571-019-00717-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/31/2019] [Indexed: 12/12/2022]
Abstract
Neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Parkinson's, Alzheimer's, and Huntington's disease affect a rapidly increasing population worldwide. Although common pathogenic mechanisms have been identified (e.g., protein aggregation or dysfunction, immune response alteration and axonal degeneration), the molecular events underlying timing, dosage, expression, and location of RNA molecules are still not fully elucidated. In particular, the alternative splicing (AS) mechanism is a crucial player in RNA processing and represents a fundamental determinant for brain development, as well as for the physiological functions of neuronal circuits. Although in recent years our knowledge of AS events has increased substantially, deciphering the molecular interconnections between splicing and ALS remains a complex task and still requires considerable efforts. In the present review, we will summarize the current scientific evidence outlining the involvement of AS in the pathogenic processes of ALS. We will also focus on recent insights concerning the tuning of splicing mechanisms by epigenomic and epi-transcriptomic regulation, providing an overview of the available genomic technologies to investigate AS drivers on a genome-wide scale, even at a single-cell level resolution. In the future, gene therapy strategies and RNA-based technologies may be utilized to intercept or modulate the splicing mechanism and produce beneficial effects against ALS.
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Affiliation(s)
- Benedetta Perrone
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Valentina La Cognata
- Institute for Biomedical Research and Innovation, National Research Council, Catania, Italy
| | - Teresa Sprovieri
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Carmine Ungaro
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Francesca Luisa Conforti
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy
| | - Sebastiano Andò
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy.,Centro Sanitario, University of Calabria, Arcavacata di Rende, Cosenza, Italy
| | - Sebastiano Cavallaro
- Institute for Biomedical Research and Innovation, National Research Council, Catania, Italy.
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23
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Sugai A, Kato T, Koyama A, Koike Y, Konno T, Ishihara T, Onodera O. Non-genetically modified models exhibit TARDBP mRNA increase due to perturbed TDP-43 autoregulation. Neurobiol Dis 2019; 130:104534. [PMID: 31310801 DOI: 10.1016/j.nbd.2019.104534] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 06/22/2019] [Accepted: 07/12/2019] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by accumulation of fragmented insoluble TDP-43 and loss of TDP-43 from the nucleus. Increased expression of exogenous TARDBP (encoding TDP-43) induces TDP-43 pathology and cytotoxicity, suggesting the involvement of aberrant expression of TDP-43 in the pathogenesis of ALS. In normal conditions, however, the amount of TDP-43 is tightly regulated by the autoregulatory mechanism involving alternative splicing of TARDBP mRNA. To investigate the influence of autoregulation dysfunction, we inhibited the splicing of cryptic intron 6 using antisense oligonucleotides in vivo. This inhibition doubled the Tardbp mRNA expression, increased the fragmented insoluble TDP-43, and reduced the number of motor neurons in the mouse spinal cord. In human induced pluripotent stem cell-derived neurons, the splicing inhibition of intron 6 increased TARDBP mRNA and decreased nuclear TDP-43. These non-genetically modified models exhibiting rise in the TARDBP mRNA levels suggest that TDP-43 autoregulation turbulence might be linked to the pathogenesis of ALS.
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Affiliation(s)
- Akihiro Sugai
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Taisuke Kato
- Department of System Pathology for Neurological Disorders, Brain Science Branch, Center for Bioresource-based Research, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Akihide Koyama
- Division of Legal Medicine, Graduate School of Medicine and Dental Science, Niigata University, Niigata 951-8585, Japan
| | - Yuka Koike
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Takuya Konno
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Tomohiko Ishihara
- Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-based Research, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Osamu Onodera
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan.
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24
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Watson CN, Belli A, Di Pietro V. Small Non-coding RNAs: New Class of Biomarkers and Potential Therapeutic Targets in Neurodegenerative Disease. Front Genet 2019; 10:364. [PMID: 31080456 PMCID: PMC6497742 DOI: 10.3389/fgene.2019.00364] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/05/2019] [Indexed: 12/11/2022] Open
Abstract
Neurodegenerative diseases (NDs) are becoming increasingly prevalent in the world, with an aging population. In the last few decades, due to the devastating nature of these diseases, the research of biomarkers has become crucial to enable adequate treatments and to monitor the progress of disease. Currently, gene mutations, CSF and blood protein markers together with the neuroimaging techniques are the most used diagnostic approaches. However, despite the efforts in the research, conflicting data still exist, highlighting the need to explore new classes of biomarkers, particularly at early stages. Small non-coding RNAs (MicroRNA, Small nuclear RNA, Small nucleolar RNA, tRNA derived small RNA and Piwi-interacting RNA) can be considered a "relatively" new class of molecule that have already proved to be differentially regulated in many NDs, hence they represent a new potential class of biomarkers to be explored. In addition, understanding their involvement in disease development could depict the underlying pathogenesis of particular NDs, so novel treatment methods that act earlier in disease progression can be developed. This review aims to describe the involvement of small non-coding RNAs as biomarkers of NDs and their potential role in future clinical applications.
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Affiliation(s)
- Callum N. Watson
- Neuroscience and Ophthalmology Research Group, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, United Kingdom
- National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
| | - Antonio Belli
- Neuroscience and Ophthalmology Research Group, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, United Kingdom
- National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
| | - Valentina Di Pietro
- Neuroscience and Ophthalmology Research Group, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, United Kingdom
- National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL, United States
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25
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Swindell WR, Bojanowski K, Kindy MS, Chau RMW, Ko D. GM604 regulates developmental neurogenesis pathways and the expression of genes associated with amyotrophic lateral sclerosis. Transl Neurodegener 2018; 7:30. [PMID: 30524706 PMCID: PMC6276193 DOI: 10.1186/s40035-018-0135-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/21/2018] [Indexed: 12/11/2022] Open
Abstract
Background Amyotrophic lateral sclerosis (ALS) is currently an incurable disease without highly effective pharmacological treatments. The peptide drug GM604 (GM6 or Alirinetide) was developed as a candidate ALS therapy, which has demonstrated safety and good drug-like properties with a favorable pharmacokinetic profile. GM6 is hypothesized to bolster neuron survival through the multi-target regulation of developmental pathways, but mechanisms of action are not fully understood. Methods This study used RNA-seq to evaluate transcriptome responses in SH-SY5Y neuroblastoma cells following GM6 treatment (6, 24 and 48 h). Results We identified 2867 protein-coding genes with expression significantly altered by GM6 (FDR < 0.10). Early (6 h) responses included up-regulation of Notch and hedgehog signaling components, with increased expression of developmental genes mediating neurogenesis and axon growth. Prolonged GM6 treatment (24 and 48 h) altered the expression of genes contributing to cell adhesion and the extracellular matrix. GM6 further down-regulated the expression of genes associated with mitochondria, inflammatory responses, mRNA processing and chromatin organization. GM6-increased genes were located near GC-rich motifs interacting with C2H2 zinc finger transcription factors, whereas GM6-decreased genes were located near AT-rich motifs associated with helix-turn-helix homeodomain factors. Such motifs interacted with a diverse network of transcription factors encoded by GM6-regulated genes (STAT3, HOXD11, HES7, GLI1). We identified 77 ALS-associated genes with expression significantly altered by GM6 treatment (FDR < 0.10), which were known to function in neurogenesis, axon guidance and the intrinsic apoptosis pathway. Conclusions Our findings support the hypothesis that GM6 acts through developmental-stage pathways to influence neuron survival. Gene expression responses were consistent with neurotrophic effects, ECM modulation, and activation of the Notch and hedgehog neurodevelopmental pathways. This multifaceted mechanism of action is unique among existing ALS drug candidates and may be applicable to multiple neurodegenerative diseases. Electronic supplementary material The online version of this article (10.1186/s40035-018-0135-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- William R Swindell
- 1Heritage College of Osteopathic Medicine, Ohio University, Athens, OH USA
| | | | - Mark S Kindy
- 3Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, FL USA.,4James A. Haley VAMC, Tampa, FL USA
| | | | - Dorothy Ko
- Genervon Biopharmaceuticals LLC, Pasadena, CA USA
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26
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Chung CY, Berson A, Kennerdell JR, Sartoris A, Unger T, Porta S, Kim HJ, Smith ER, Shilatifard A, Van Deerlin V, Lee VMY, Chen-Plotkin A, Bonini NM. Aberrant activation of non-coding RNA targets of transcriptional elongation complexes contributes to TDP-43 toxicity. Nat Commun 2018; 9:4406. [PMID: 30353006 PMCID: PMC6199344 DOI: 10.1038/s41467-018-06543-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 09/11/2018] [Indexed: 12/13/2022] Open
Abstract
TDP-43 is the major disease protein associated with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-TDP). Here we identify the transcriptional elongation factor Ell—a shared component of little elongation complex (LEC) and super elongation complex (SEC)—as a strong modifier of TDP-43-mediated neurodegeneration. Our data indicate select targets of LEC and SEC become upregulated in the fly ALS/FTLD-TDP model. Among them, U12 snRNA and a stress-induced long non-coding RNA Hsrω, functionally contribute to TDP-43-mediated degeneration. We extend the findings of Hsrω, which we identify as a chromosomal target of TDP-43, to show that the human orthologue Sat III is elevated in a human cellular disease model and FTLD-TDP patient tissue. We further demonstrate an interaction between TDP-43 and human ELL2 by co-immunoprecipitation from human cells. These findings reveal important roles of Ell-complexes LEC and SEC in TDP-43-associated toxicity, providing potential therapeutic insight for TDP-43-associated neurodegeneration. TDP-43 is associated with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitinated inclusions (FTD-TDP). Here, the authors identify the transcriptional elongation factor Ell as a strong modifier of TDP-43-mediated neurodegeneration through the Ell transcriptional elongation complexes LEC and SEC.
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Affiliation(s)
- Chia-Yu Chung
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Cell and Molecular Biology Graduate Group, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Amit Berson
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jason R Kennerdell
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ashley Sartoris
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Travis Unger
- Department of Neurology, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Sílvia Porta
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Hyung-Jun Kim
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Neural Development and Disease, Korea Brain Research Institute (KBRI), Daegu, 41068, South Korea
| | - Edwin R Smith
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Ali Shilatifard
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Vivianna Van Deerlin
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Virginia M-Y Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Alice Chen-Plotkin
- Cell and Molecular Biology Graduate Group, Perelman School of Medicine, Philadelphia, PA, 19104, USA.,Department of Neurology, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Nancy M Bonini
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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27
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Abstract
Trans activation response DNA/RNA-binding protein 43 kDa (TDP-43) regulates RNA splicing and stability. TDP-43 is a component of ubiquitin-positive inclusion bodies of motor neurons from patients with amyotrophic lateral sclerosis, suggesting a role in disease pathogenesis. Toxic intracellular TDP-43 aggregation may cause neuronal cell death. The loss of TDP-43 in animal models causes lethality in early development. Furthermore, TDP-43 knockdown in adult animals and cells increases aberrant splicing. Uridine-rich small nuclear RNA (U snRNA) regulation is disrupted in cultured neuroblastoma cells with TDP-43 knockdown and in motor neurons in amyotrophic lateral sclerosis. Aberrant mRNA splicing and U snRNA expression are likely key processes in neuronal cell death. We review the research history and future perspectives of aberrant splicing by TDP-43 loss.
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Affiliation(s)
- Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan 001-0021
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28
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Conlon EG, Fagegaltier D, Agius P, Davis-Porada J, Gregory J, Hubbard I, Kang K, Kim D, Phatnani H, Shneider NA, Manley JL. Unexpected similarities between C9ORF72 and sporadic forms of ALS/FTD suggest a common disease mechanism. eLife 2018; 7:37754. [PMID: 30003873 PMCID: PMC6103746 DOI: 10.7554/elife.37754] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 07/09/2018] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) represent two ends of a disease spectrum with shared clinical, genetic and pathological features. These include near ubiquitous pathological inclusions of the RNA-binding protein (RBP) TDP-43, and often the presence of a GGGGCC expansion in the C9ORF72 (C9) gene. Previously, we reported that the sequestration of hnRNP H altered the splicing of target transcripts in C9ALS patients (Conlon et al., 2016). Here, we show that this signature also occurs in half of 50 postmortem sporadic, non-C9 ALS/FTD brains. Furthermore, and equally surprisingly, these ‘like-C9’ brains also contained correspondingly high amounts of insoluble TDP-43, as well as several other disease-related RBPs, and this correlates with widespread global splicing defects. Finally, we show that the like-C9 sporadic patients, like actual C9ALS patients, were much more likely to have developed FTD. We propose that these unexpected links between C9 and sporadic ALS/FTD define a common mechanism in this disease spectrum.
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Affiliation(s)
- Erin G Conlon
- Department of Biological Sciences, Columbia University, New York, United States
| | - Delphine Fagegaltier
- Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, United States
| | | | - Julia Davis-Porada
- Department of Biological Sciences, Columbia University, New York, United States
| | - James Gregory
- Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, United States
| | - Isabel Hubbard
- Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, United States
| | - Kristy Kang
- Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, United States
| | - Duyang Kim
- Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, United States
| | | | - Hemali Phatnani
- Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, United States
| | - Neil A Shneider
- Department of Neurology, Columbia University Medical Center, New York, United States
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, United States
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29
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Dvinge H. Regulation of alternative
mRNA
splicing: old players and new perspectives. FEBS Lett 2018; 592:2987-3006. [DOI: 10.1002/1873-3468.13119] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 05/23/2018] [Accepted: 05/29/2018] [Indexed: 12/22/2022]
Affiliation(s)
- Heidi Dvinge
- Department of Biomolecular Chemistry School of Medicine and Public Health University of Wisconsin‐Madison WI USA
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30
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Jutzi D, Akinyi MV, Mechtersheimer J, Frilander MJ, Ruepp MD. The emerging role of minor intron splicing in neurological disorders. Cell Stress 2018; 2:40-54. [PMID: 31225466 PMCID: PMC6558932 DOI: 10.15698/cst2018.03.126] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pre-mRNA splicing is an essential step in eukaryotic gene expression. Mutations in cis-acting sequence elements within pre-mRNA molecules or trans-acting factors involved in pre-mRNA processing have both been linked to splicing dysfunction that give rise to a large number of human diseases. These mutations typically affect the major splicing pathway, which excises more than 99% of all introns in humans. However, approximately 700-800 human introns feature divergent intron consensus sequences at their 5' and 3' ends and are recognized by a separate pre-mRNA processing machinery denoted as the minor spliceosome. This spliceosome has been studied less than its major counterpart, but has received increasing attention during the last few years as a novel pathomechanistic player on the stage in neurodevelopmental and neurodegenerative diseases. Here, we review the current knowledge on minor spliceosome function and discuss its potential pathomechanistic role and impact in neurodegeneration.
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Affiliation(s)
- Daniel Jutzi
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Maureen V Akinyi
- Institute of Biotechnology, University of Helsinki, FI-00014, Finland
| | - Jonas Mechtersheimer
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Mikko J Frilander
- Institute of Biotechnology, University of Helsinki, FI-00014, Finland
| | - Marc-David Ruepp
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.,United Kingdom Dementia Research Institute Centre, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9NU London, UK
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31
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Minor spliceosome and disease. Semin Cell Dev Biol 2017; 79:103-112. [PMID: 28965864 DOI: 10.1016/j.semcdb.2017.09.036] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 09/21/2017] [Accepted: 09/27/2017] [Indexed: 01/09/2023]
Abstract
The U12-dependent (minor) spliceosome excises a rare group of introns that are characterized by a highly conserved 5' splice site and branch point sequence. Several new congenital or somatic diseases have recently been associated with mutations in components of the minor spliceosome. A common theme in these diseases is the detection of elevated levels of transcripts containing U12-type introns, of which a subset is associated with other splicing defects. Here we review the present understanding of minor spliceosome diseases, particularly those associated with the specific components of the minor spliceosome. We also present a model for interpreting the molecular-level consequences of the different diseases.
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32
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Tosolini AP, Sleigh JN. Motor Neuron Gene Therapy: Lessons from Spinal Muscular Atrophy for Amyotrophic Lateral Sclerosis. Front Mol Neurosci 2017; 10:405. [PMID: 29270111 PMCID: PMC5725447 DOI: 10.3389/fnmol.2017.00405] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/21/2017] [Indexed: 12/11/2022] Open
Abstract
Spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS) are severe nervous system diseases characterized by the degeneration of lower motor neurons. They share a number of additional pathological, cellular, and genetic parallels suggesting that mechanistic and clinical insights into one disorder may have value for the other. While there are currently no clinical ALS gene therapies, the splice-switching antisense oligonucleotide, nusinersen, was recently approved for SMA. This milestone was achieved through extensive pre-clinical research and patient trials, which together have spawned fundamental insights into motor neuron gene therapy. We have thus tried to distil key information garnered from SMA research, in the hope that it may stimulate a more directed approach to ALS gene therapy. Not only must the type of therapeutic (e.g., antisense oligonucleotide vs. viral vector) be sensibly selected, but considerable thought must be applied to the where, which, what, and when in order to enhance treatment benefit: to where (cell types and tissues) must the drug be delivered and how can this be best achieved? Which perturbed pathways must be corrected and can they be concurrently targeted? What dosing regime and concentration should be used? When should medication be administered? These questions are intuitive, but central to identifying and optimizing a successful gene therapy. Providing definitive solutions to these quandaries will be difficult, but clear thinking about therapeutic testing is necessary if we are to have the best chance of developing viable ALS gene therapies and improving upon early generation SMA treatments.
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Affiliation(s)
- Andrew P Tosolini
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
| | - James N Sleigh
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
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33
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Mitsuhashi K, Ito D, Mashima K, Oyama M, Takahashi S, Suzuki N. De novo design of RNA-binding proteins with a prion-like domain related to ALS/FTD proteinopathies. Sci Rep 2017; 7:16871. [PMID: 29203801 PMCID: PMC5715010 DOI: 10.1038/s41598-017-17209-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/21/2017] [Indexed: 12/12/2022] Open
Abstract
Aberrant RNA-binding proteins form the core of the neurodegeneration cascade in spectrums of disease, such as amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). Six ALS-related molecules, TDP-43, FUS, TAF15, EWSR1, heterogeneous nuclear (hn)RNPA1 and hnRNPA2 are RNA-binding proteins containing candidate mutations identified in ALS patients and those share several common features, including harboring an aggregation-prone prion-like domain (PrLD) containing a glycine/serine-tyrosine-glycine/serine (G/S-Y-G/S)-motif-enriched low-complexity sequence and rich in glutamine and/or asparagine. Additinally, these six molecules are components of RNA granules involved in RNA quality control and become mislocated from the nucleus to form cytoplasmic inclusion bodies (IBs) in the ALS/FTD-affected brain. To reveal the essential mechanisms involved in ALS/FTD-related cytotoxicity associated with RNA-binding proteins containing PrLDs, we designed artificial RNA-binding proteins harboring G/S-Y-G/S-motif repeats with and without enriched glutamine residues and nuclear-import/export-signal sequences and examined their cytotoxicity in vitro. These proteins recapitulated features of ALS-linked molecules, including insoluble aggregation, formation of cytoplasmic IBs and components of RNA granules, and cytotoxicity instigation. These findings indicated that these artificial RNA-binding proteins mimicked features of ALS-linked molecules and allowed the study of mechanisms associated with gain of toxic functions related to ALS/FTD pathogenesis.
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Affiliation(s)
- Kana Mitsuhashi
- Departments of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Daisuke Ito
- Departments of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
| | - Kyoko Mashima
- Departments of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Munenori Oyama
- Departments of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Shinichi Takahashi
- Departments of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Norihiro Suzuki
- Departments of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
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34
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Yahara M, Kitamura A, Kinjo M. U6 snRNA expression prevents toxicity in TDP-43-knockdown cells. PLoS One 2017; 12:e0187813. [PMID: 29125873 PMCID: PMC5681290 DOI: 10.1371/journal.pone.0187813] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/26/2017] [Indexed: 12/13/2022] Open
Abstract
Depletion of amyotrophic lateral sclerosis (ALS)-associated transactivation response (TAR) RNA/DNA-binding protein 43 kDa (TDP-43) alters splicing efficiency of multiple transcripts and results in neuronal cell death. TDP-43 depletion can also disturb expression levels of small nuclear RNAs (snRNAs) as spliceosomal components. Despite this knowledge, the relationship between cell death and alteration of snRNA expression during TDP-43 depletion remains unclear. Here, we knocked down TDP-43 in murine neuroblastoma Neuro2A cells and found a time lag between efficient TDP-43 depletion and appearance of cell death, suggesting that several mechanisms mediate between these two events. The amount of U6 snRNA was significantly decreased during TDP-43 depletion prior to increase of cell death, whereas that of U1, U2, and U4 snRNAs was not. Downregulation of U6 snRNA led to cell death, whereas transient exogenous expression of U6 snRNA counteracted the effect of TDP-43 knockdown on cell death, and slightly decreased the mis-splicing rate of Dnajc5 and Sortilin 1 transcripts, which are assisted by TDP-43. These results suggest that regulation of the U6 snRNA expression level by TDP-43 is a key factor in the increase in cell death upon TDP-43 loss-of-function.
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Affiliation(s)
- Masao Yahara
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
- * E-mail:
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35
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Abstract
Much evidence is now accumulating that, in addition to their general role in splicing, the components of the core splicing machinery have extensive regulatory potential. In particular, recent evidence has demonstrated that de-regulation of these factors cause the highest extent of alternative splicing changes compared to de-regulation of the classical splicing regulators. This lack of a general inhibition of splicing resonates the differential splicing effects observed in different disease pathologies associated with specific mutations targeting core spliceosomal components. In this review we will summarize what is currently known regarding the involvement of core spliceosomal U-snRNP complexes in perturbed tissue development and human diseases and argue for the existence of a compensatory mechanism enabling cells to cope with drastic perturbations in core splicing components. This system maintains the correct balance of spliceosomal snRNPs through differential expression of variant (v)U-snRNPs.
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Affiliation(s)
- Pilar Vazquez-Arango
- a Nuffield Department of Obstetrics and Gynaecology, Level 3 , Women's Centre, John Radcliffe Hospital , Oxford , England
| | - Dawn O'Reilly
- b Sir William Dunn School of pathology , University of Oxford , South Parks Road, Oxford , England
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36
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Staněk D, Fox AH. Nuclear bodies: news insights into structure and function. Curr Opin Cell Biol 2017; 46:94-101. [PMID: 28577509 DOI: 10.1016/j.ceb.2017.05.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 04/20/2017] [Accepted: 05/10/2017] [Indexed: 02/07/2023]
Abstract
The cell nucleus contains a number of different dynamic bodies that are variously composed of proteins and generally, but not always, specific RNA molecules. Recent studies have revealed new understanding about nuclear body formation and function in different aspects of nuclear metabolism. Here, we focus on findings describing the role of nuclear bodies in the biogenesis of specific ribonucleoprotein complexes, processing of key mRNAs, and subnuclear sequestration of protein factors. We highlight how nuclear bodies are involved in stress responses, innate immunity and tumorigenesis. We further review organization of nuclear bodies and principles that govern their assembly, highlighting the pivotal role of scaffolding noncoding RNAs, and liquid-liquid phase separation, which are transforming our picture of nuclear body formation.
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Affiliation(s)
- David Staněk
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Archa H Fox
- School of Human Sciences and Molecular Sciences, The University of Western Australia and Harry Perkins Institute of Medical Research, Centre for Medical Research, The University of Western Australia, Crawley, 6009 Western Australia, Australia.
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37
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Faulty RNA splicing: consequences and therapeutic opportunities in brain and muscle disorders. Hum Genet 2017; 136:1215-1235. [DOI: 10.1007/s00439-017-1802-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/13/2017] [Indexed: 12/12/2022]
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38
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Gama-Carvalho M, L Garcia-Vaquero M, R Pinto F, Besse F, Weis J, Voigt A, Schulz JB, De Las Rivas J. Linking amyotrophic lateral sclerosis and spinal muscular atrophy through RNA-transcriptome homeostasis: a genomics perspective. J Neurochem 2017; 141:12-30. [PMID: 28054357 DOI: 10.1111/jnc.13945] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/02/2016] [Accepted: 12/24/2016] [Indexed: 12/11/2022]
Abstract
In this review, we present our most recent understanding of key biomolecular processes that underlie two motor neuron degenerative disorders, amyotrophic lateral sclerosis, and spinal muscular atrophy. We focus on the role of four multifunctional proteins involved in RNA metabolism (TDP-43, FUS, SMN, and Senataxin) that play a causal role in these diseases. Recent results have led to a novel scenario of intricate connections between these four proteins, bringing transcriptome homeostasis into the spotlight as a common theme in motor neuron degeneration. We review reported functional and physical interactions between these four proteins, highlighting their common association with nuclear bodies and small nuclear ribonucleoprotein particle biogenesis and function. We discuss how these interactions are turning out to be particularly relevant for the control of transcription and chromatin homeostasis, including the recent identification of an association between SMN and Senataxin required to ensure the resolution of DNA-RNA hybrid formation and proper termination by RNA polymerase II. These connections strongly support the existence of common pathways underlying the spinal muscular atrophy and amyotrophic lateral sclerosis phenotype. We also discuss the potential of genome-wide expression profiling, in particular RNA sequencing derived data, to contribute to unravelling the underlying mechanisms. We provide a review of publicly available datasets that have addressed both diseases using these approaches, and highlight the value of investing in cross-disease studies to promote our understanding of the pathways leading to neurodegeneration.
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Affiliation(s)
- Margarida Gama-Carvalho
- Universidade de Lisboa, Faculdade de Ciências, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisboa, Portugal
| | - Marina L Garcia-Vaquero
- Universidade de Lisboa, Faculdade de Ciências, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisboa, Portugal
| | - Francisco R Pinto
- Universidade de Lisboa, Faculdade de Ciências, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisboa, Portugal
| | | | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
| | - Aaron Voigt
- Department of Neurology, University Hospital, RWTH Aachen University, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Jörg B Schulz
- Department of Neurology, University Hospital, RWTH Aachen University, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Javier De Las Rivas
- Cancer Research Center (CiC-IBMCC, CSIC/USAL/IBSAL), Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca (USAL), Salamanca, Spain
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39
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Tu WY, Simpson JE, Highley JR, Heath PR. Spinal muscular atrophy: Factors that modulate motor neurone vulnerability. Neurobiol Dis 2017; 102:11-20. [PMID: 28161391 DOI: 10.1016/j.nbd.2017.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/10/2017] [Accepted: 01/31/2017] [Indexed: 01/07/2023] Open
Abstract
Spinal muscular atrophy (SMA), a leading genetic cause of infant death, is a neurodegenerative disease characterised by the selective loss of particular groups of motor neurones in the anterior horn of the spinal cord with concomitant muscle weakness. To date, no effective treatment is available, however, there are ongoing clinical trials are in place which promise much for the future. However, there remains an ongoing problem in trying to link a single gene loss to motor neurone degeneration. Fortunately, given successful disease models that have been established and intensive studies on SMN functions in the past ten years, we are fast approaching the stage of identifying the underlying mechanisms of SMA pathogenesis Here we discuss potential disease modifying factors on motor neurone vulnerability, in the belief that these factors give insight into the pathological mechanisms of SMA and therefore possible therapeutic targets.
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Affiliation(s)
- Wen-Yo Tu
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Julie E Simpson
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - J Robin Highley
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Paul R Heath
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK.
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40
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Rossi S, Cozzolino M, Carrì MT. Old versus New Mechanisms in the Pathogenesis of ALS. Brain Pathol 2016; 26:276-86. [PMID: 26779612 DOI: 10.1111/bpa.12355] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 01/14/2016] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is recognized as a very complex disease. As we have learned in the past 20 years from studies in patients and in models based on the expression of mutant SOD1, ALS is not a purely motor neuron disease as previously thought. While undoubtedly motor neurons are lost in patients, a number of alterations in those cell-types that interact functionally with motor neurons (astrocytes, microglia, muscle fibers, oligodendrocytes) take place even long before onset of symptoms. At the same time, disturbance of several, only partly inter-related physiological functions play some role in the onset and progression of the disease. Traditionally, mitochondrial damage and oxidative stress, excitotoxicity, neuroinflammation, altered axonal transport, ER stress, protein aggregation and defective removal of toxic proteins have been considered as key factors in the pathogenesis of ALS, with the relatively recent addition of disturbances in RNA metabolism. This complexity makes the search for an effective treatment extremely difficult and prompts further studies to reveal other possible, previously unappreciated aspects of the pathogenesis of ALS. In this review, we focus on previous knowledge on ALS mechanisms as well as new facets emerging from studies on genetic ALS patients and models that may both provide precious information for a novel therapeutic approach.
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Affiliation(s)
- Simona Rossi
- Institute of Translational Pharmacology, National Research Council (CNR), Rome, Italy
| | - Mauro Cozzolino
- Institute of Translational Pharmacology, National Research Council (CNR), Rome, Italy.,Lab of Neurochemistry, Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Maria Teresa Carrì
- Lab of Neurochemistry, Fondazione Santa Lucia IRCCS, Rome, Italy.,Department of Biology, University of Rome Tor Vergata
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Abstract
Cajal is commonly regarded as the father of modern neuroscience in recognition of his fundamental work on the structure of the nervous system. But Cajal also made seminal contributions to the knowledge of nuclear structure in the early 1900s, including the discovery of the "accessory body" later renamed "Cajal body" (CB). This important nuclear structure has emerged as a center for the assembly of ribonucleoproteins (RNPs) required for splicing, ribosome biogenesis and telomere maintenance. The modern era of CB research started in the 1990s with the discovery of coilin, now known as a scaffold protein of CBs, and specific probes for small nuclear RNAs (snRNAs). In this review, we summarize what we have learned in the recent decades concerning CBs in post-mitotic neurons, thereby ruling out dynamic changes in CB functions during the cell cycle. We show that CBs are particularly prominent in neurons, where they frequently associate with the nucleolus. Neuronal CBs are transcription-dependent nuclear organelles. Indeed, their number dynamically accommodates to support the high neuronal demand for splicing and ribosome biogenesis required for sustaining metabolic and bioelectrical activity. Mature neurons have canonical CBs enriched in coilin, survival motor neuron protein and snRNPs. Disruption and loss of neuronal CBs associate with severe neuronal dysfunctions in several neurological disorders such as motor neuron diseases. In particular, CB depletion in motor neurons seems to reflect a perturbation of transcription and splicing in spinal muscular atrophy, the most common genetic cause of infant mortality.
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Affiliation(s)
- Miguel Lafarga
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
| | - Olga Tapia
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
| | - Ana M Romero
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
| | - Maria T Berciano
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
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42
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Boeynaems S, Bogaert E, Van Damme P, Van Den Bosch L. Inside out: the role of nucleocytoplasmic transport in ALS and FTLD. Acta Neuropathol 2016; 132:159-173. [PMID: 27271576 PMCID: PMC4947127 DOI: 10.1007/s00401-016-1586-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/27/2016] [Accepted: 05/28/2016] [Indexed: 12/11/2022]
Abstract
Neurodegenerative diseases are characterized by the presence of protein inclusions with a different protein content depending on the type of disease. Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are no exceptions to this common theme. In most ALS and FTLD cases, the predominant pathological species are RNA-binding proteins. Interestingly, these proteins are both depleted from their normal nuclear localization and aggregated in the cytoplasm. This key pathological feature has suggested a potential dual mechanism with both nuclear loss of function and cytoplasmic gain of function being at play. Yet, why and how this pathological cascade is initiated in most patients, and especially sporadic cases, is currently unresolved. Recent breakthroughs in C9orf72 ALS/FTLD disease models point at a pivotal role for the nuclear transport system in toxicity. To address whether defects in nuclear transport are indeed implicated in the disease, we reviewed two decades of ALS/FTLD literature and combined this with bioinformatic analyses. We find that both RNA-binding proteins and nuclear transport factors are key players in ALS/FTLD pathology. Moreover, our analyses suggest that disturbances in nucleocytoplasmic transport play a crucial initiating role in the disease, by bridging both nuclear loss and cytoplasmic gain of functions. These findings highlight this process as a novel and promising therapeutic target for ALS and FTLD.
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Affiliation(s)
- Steven Boeynaems
- />Department of Neurosciences, Experimental Neurology and Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven-University of Leuven, 3000 Leuven, Belgium
- />Laboratory of Neurobiology, Vesalius Research Center, VIB, Campus Gasthuisberg O&N4, PB912, Herestraat 49, 3000 Leuven, Belgium
| | - Elke Bogaert
- />Department of Neurosciences, Experimental Neurology and Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven-University of Leuven, 3000 Leuven, Belgium
- />Laboratory of Neurobiology, Vesalius Research Center, VIB, Campus Gasthuisberg O&N4, PB912, Herestraat 49, 3000 Leuven, Belgium
| | - Philip Van Damme
- />Department of Neurosciences, Experimental Neurology and Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven-University of Leuven, 3000 Leuven, Belgium
- />Laboratory of Neurobiology, Vesalius Research Center, VIB, Campus Gasthuisberg O&N4, PB912, Herestraat 49, 3000 Leuven, Belgium
| | - Ludo Van Den Bosch
- />Department of Neurosciences, Experimental Neurology and Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven-University of Leuven, 3000 Leuven, Belgium
- />Laboratory of Neurobiology, Vesalius Research Center, VIB, Campus Gasthuisberg O&N4, PB912, Herestraat 49, 3000 Leuven, Belgium
- />Department of Neurology, University Hospitals Leuven, 3000 Leuven, Belgium
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43
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Shiihashi G, Ito D, Yagi T, Nihei Y, Ebine T, Suzuki N. Mislocated FUS is sufficient for gain-of-toxic-function amyotrophic lateral sclerosis phenotypes in mice. Brain 2016; 139:2380-94. [PMID: 27368346 DOI: 10.1093/brain/aww161] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 05/26/2016] [Indexed: 12/12/2022] Open
Abstract
Mutations in RNA-binding proteins, including fused in sarcoma (FUS) and TAR DNA-binding protein 43 (TDP-43, encoded by TARDBP), are associated with sporadic and familial amyotrophic lateral sclerosis. A major question is whether neuronal loss is caused by toxic gain-of-function cytoplasmic aggregates or loss of nuclear RNA-binding protein function. We generated a transgenic mouse overexpressing exogenous FUS without a nuclear localization signal (ΔNLS-FUS), which developed progressive spastic motor deficits and neuronal loss in the motor cortex. The ΔNLS-FUS protein was restricted to the cytoplasm and formed ubiquitin/p62-positive aggregates. Endogenous FUS expression, nuclear localization, and splicing activity were not altered, indicating that mislocated FUS is sufficient for proteinopathy. Crossing ΔNLS-FUS with wild-type human TDP-43 transgenic mice exacerbated pathological and behavioural phenotypes, suggesting that both proteins are involved in a common cascade. RNA-sequence analysis revealed specific transcriptome alterations, including genes regulating dynein-associated molecules and endoplasmic reticulum stress. ΔNLS-FUS mice are promising tools for understanding amyotrophic lateral sclerosis pathogenesis and testing new therapeutic approaches.
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Affiliation(s)
- Gen Shiihashi
- 1 Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku,Tokyo 160-8582, Japan
| | - Daisuke Ito
- 1 Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku,Tokyo 160-8582, Japan
| | - Takuya Yagi
- 1 Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku,Tokyo 160-8582, Japan 2 Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yoshihiro Nihei
- 1 Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku,Tokyo 160-8582, Japan 3 Biomedical Research Center, Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 17, 81377 Munich, Germany
| | - Taeko Ebine
- 1 Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku,Tokyo 160-8582, Japan
| | - Norihiro Suzuki
- 1 Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku,Tokyo 160-8582, Japan
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44
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Reber S, Stettler J, Filosa G, Colombo M, Jutzi D, Lenzken SC, Schweingruber C, Bruggmann R, Bachi A, Barabino SM, Mühlemann O, Ruepp MD. Minor intron splicing is regulated by FUS and affected by ALS-associated FUS mutants. EMBO J 2016; 35:1504-21. [PMID: 27252488 DOI: 10.15252/embj.201593791] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 04/29/2016] [Indexed: 12/11/2022] Open
Abstract
Fused in sarcoma (FUS) is a ubiquitously expressed RNA-binding protein proposed to function in various RNA metabolic pathways, including transcription regulation, pre-mRNA splicing, RNA transport and microRNA processing. Mutations in the FUS gene were identified in patients with amyotrophic lateral sclerosis (ALS), but the pathomechanisms by which these mutations cause ALS are not known. Here, we show that FUS interacts with the minor spliceosome constituent U11 snRNP, binds preferentially to minor introns and directly regulates their removal. Furthermore, a FUS knockout in neuroblastoma cells strongly disturbs the splicing of minor intron-containing mRNAs, among them mRNAs required for action potential transmission and for functional spinal motor units. Moreover, an ALS-associated FUS mutant that forms cytoplasmic aggregates inhibits splicing of minor introns by trapping U11 and U12 snRNAs in these aggregates. Collectively, our findings suggest a possible pathomechanism for ALS in which mutated FUS inhibits correct splicing of minor introns in mRNAs encoding proteins required for motor neuron survival.
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Affiliation(s)
- Stefan Reber
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Jolanda Stettler
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Giuseppe Filosa
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy IFOM-FIRC Institute of Molecular Oncology, Milan, Italy
| | - Martino Colombo
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Daniel Jutzi
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Silvia C Lenzken
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Christoph Schweingruber
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Rémy Bruggmann
- Interfaculty Bioinformatics Unit and Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
| | - Angela Bachi
- IFOM-FIRC Institute of Molecular Oncology, Milan, Italy
| | - Silvia Ml Barabino
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Marc-David Ruepp
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
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45
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Butchbach MER. Copy Number Variations in the Survival Motor Neuron Genes: Implications for Spinal Muscular Atrophy and Other Neurodegenerative Diseases. Front Mol Biosci 2016; 3:7. [PMID: 27014701 PMCID: PMC4785180 DOI: 10.3389/fmolb.2016.00007] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/25/2016] [Indexed: 12/11/2022] Open
Abstract
Proximal spinal muscular atrophy (SMA), a leading genetic cause of infant death worldwide, is an early-onset, autosomal recessive neurodegenerative disease characterized by the loss of spinal α-motor neurons. This loss of α-motor neurons is associated with muscle weakness and atrophy. SMA can be classified into five clinical grades based on age of onset and severity of the disease. Regardless of clinical grade, proximal SMA results from the loss or mutation of SMN1 (survival motor neuron 1) on chromosome 5q13. In humans a large tandem chromosomal duplication has lead to a second copy of the SMN gene locus known as SMN2. SMN2 is distinguishable from SMN1 by a single nucleotide difference that disrupts an exonic splice enhancer in exon 7. As a result, most of SMN2 mRNAs lack exon 7 (SMNΔ7) and produce a protein that is both unstable and less than fully functional. Although only 10–20% of the SMN2 gene product is fully functional, increased genomic copies of SMN2 inversely correlates with disease severity among individuals with SMA. Because SMN2 copy number influences disease severity in SMA, there is prognostic value in accurate measurement of SMN2 copy number from patients being evaluated for SMA. This prognostic value is especially important given that SMN2 copy number is now being used as an inclusion criterion for SMA clinical trials. In addition to SMA, copy number variations (CNVs) in the SMN genes can affect the clinical severity of other neurological disorders including amyotrophic lateral sclerosis (ALS) and progressive muscular atrophy (PMA). This review will discuss how SMN1 and SMN2 CNVs are detected and why accurate measurement of SMN1 and SMN2 copy numbers is relevant for SMA and other neurodegenerative diseases.
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Affiliation(s)
- Matthew E R Butchbach
- Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for ChildrenWilmington, DE, USA; Center for Pediatric Research, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for ChildrenWilmington, DE, USA; Department of Biological Sciences, University of DelawareNewark, DE, USA; Department of Pediatrics, Thomas Jefferson UniversityPhiladelphia, PA, USA
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46
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Tanaka Y, Nonaka T, Suzuki G, Kametani F, Hasegawa M. Gain-of-function profilin 1 mutations linked to familial amyotrophic lateral sclerosis cause seed-dependent intracellular TDP-43 aggregation. Hum Mol Genet 2016; 25:1420-33. [PMID: 26908597 DOI: 10.1093/hmg/ddw024] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 01/25/2016] [Indexed: 12/12/2022] Open
Abstract
Profilin 1 (PFN1) is an actin monomer-binding protein essential for regulating cytoskeletal dynamics in all cell types. Recently, mutations in the PFN1 gene have been identified as a cause of familial amyotrophic lateral sclerosis (ALS). The co-aggregation of PFN1 bearing mutations that cause ALS with TDP-43 (a key molecule in both sporadic and some familial forms of ALS), together with the classical TDP-43 pathology detected in post-mortem tissues of patients with autosomal dominant PFN1 mutation, imply that gain-of-toxic-function of PFN1 mutants is associated with the onset of ALS. However, it remains unknown how PFN1 mutants cause ALS. We found mutant PFN1 that causes ALS formed cytoplasmic aggregates positive for ubiquitin and p62, and these aggregates sequestered endogenous TDP-43. In cells harboring PFN1 aggregates, formation of aggresome-like structures was inhibited in the presence of proteasome inhibitor, and conversion of LC3-I to LC3-II was suppressed in the presence of lysosome inhibitor. Further, insoluble TDP-43 was increased in both cases. Co-expression of ALS-linked mutant PFN1 and TDP-43 increased insoluble and phosphorylated TDP-43 levels. The C-terminal region of TDP-43, essential for aggregation of TDP-43, was also indispensable for the interaction with PFN1. Interestingly, insoluble fractions prepared from cells expressing ALS-linked mutant PFN1 functioned as a seed to induce accumulation and phosphorylation of TDP-43, indicating that TDP-43 accumulated in the presence of the PFN1 mutants is converted to prion-like species. These findings provide new insight into the mechanisms of neurodegeneration in ALS, suggesting that gain-of-toxic-function PFN1 gene mutation leads to conformational change of TDP-43.
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Affiliation(s)
- Yoshinori Tanaka
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Takashi Nonaka
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Genjiro Suzuki
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Fuyuki Kametani
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Masato Hasegawa
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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47
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Daguenet E, Dujardin G, Valcárcel J. The pathogenicity of splicing defects: mechanistic insights into pre-mRNA processing inform novel therapeutic approaches. EMBO Rep 2015; 16:1640-55. [PMID: 26566663 DOI: 10.15252/embr.201541116] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/12/2015] [Indexed: 12/22/2022] Open
Abstract
Removal of introns from pre-mRNA precursors (pre-mRNA splicing) is a necessary step for the expression of most genes in multicellular organisms, and alternative patterns of intron removal diversify and regulate the output of genomic information. Mutation or natural variation in pre-mRNA sequences, as well as in spliceosomal components and regulatory factors, has been implicated in the etiology and progression of numerous pathologies. These range from monogenic to multifactorial genetic diseases, including metabolic syndromes, muscular dystrophies, neurodegenerative and cardiovascular diseases, and cancer. Understanding the molecular mechanisms associated with splicing-related pathologies can provide key insights into the normal function and physiological context of the complex splicing machinery and establish sound basis for novel therapeutic approaches.
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Affiliation(s)
- Elisabeth Daguenet
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain
| | - Gwendal Dujardin
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain
| | - Juan Valcárcel
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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48
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Lourenco GF, Janitz M, Huang Y, Halliday GM. Long noncoding RNAs in TDP-43 and FUS/TLS-related frontotemporal lobar degeneration (FTLD). Neurobiol Dis 2015. [DOI: 10.1016/j.nbd.2015.07.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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49
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Wertz MH, Sahin M. Developing therapies for spinal muscular atrophy. Ann N Y Acad Sci 2015; 1366:5-19. [PMID: 26173388 DOI: 10.1111/nyas.12813] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 05/05/2015] [Accepted: 05/18/2015] [Indexed: 12/17/2022]
Abstract
Spinal muscular atrophy is an autosomal-recessive pediatric neurodegenerative disease characterized by loss of spinal motor neurons. It is caused by mutation in the gene survival of motor neuron 1 (SMN1), leading to loss of function of the full-length SMN protein. SMN has a number of functions in neurons, including RNA splicing and snRNP biogenesis in the nucleus, and RNA trafficking in neurites. The expression level of full-length SMN protein from the SMN2 locus modifies disease severity. Increasing full-length SMN protein by a small amount can lead to significant improvements in the neurological phenotype. Currently available interventions for spinal muscular atrophy patients are physical therapy and orthopedic, nutritional, and pulmonary interventions; these are palliative or supportive measures and do not address the etiology of the disease. In the past decade, there has been a push for developing therapeutics to improve motor phenotypes and increase life span of spinal muscular atrophy patients. These therapies are aimed primarily at restoration of full-length SMN protein levels, but other neuroprotective treatments have been investigated as well. Here, we discuss recent advances in basic and clinical studies toward finding safe and effective treatments of spinal muscular atrophy using gene therapy, antisense oligonucleotides, and other small molecule modulators of SMN expression.
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Affiliation(s)
- Mary H Wertz
- The F.M. Kirby Neurobiology Center, Department of Neurology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts
| | - Mustafa Sahin
- The F.M. Kirby Neurobiology Center, Department of Neurology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts
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50
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Highley JR, Kirby J, Jansweijer JA, Webb PS, Hewamadduma CA, Heath PR, Higginbottom A, Raman R, Ferraiuolo L, Cooper-Knock J, McDermott CJ, Wharton SB, Shaw PJ, Ince PG. Loss of nuclear TDP-43 in amyotrophic lateral sclerosis (ALS) causes altered expression of splicing machinery and widespread dysregulation of RNA splicing in motor neurones. Neuropathol Appl Neurobiol 2015; 40:670-85. [PMID: 24750229 DOI: 10.1111/nan.12148] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 04/04/2014] [Indexed: 12/14/2022]
Abstract
AIMS Loss of nuclear TDP-43 characterizes sporadic and most familial forms of amyotrophic lateral sclerosis (ALS). TDP-43 (encoded by TARDBP) has multiple roles in RNA processing. We aimed to determine whether (1) RNA splicing dysregulation is present in lower motor neurones in ALS and in a motor neurone-like cell model; and (2) TARDBP mutations (mtTARDBP) are associated with aberrant RNA splicing using patient-derived fibroblasts. METHODS Affymetrix exon arrays were used to study mRNA expression and splicing in lower motor neurones obtained by laser capture microdissection of autopsy tissue from individuals with sporadic ALS and TDP-43 proteinopathy. Findings were confirmed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and in NSC34 motor neuronal cells following shRNA-mediated TDP-43 depletion. Exon arrays and immunohistochemistry were used to study mRNA splicing and TDP-43 expression in fibroblasts from patients with mtTARDBP-associated, sporadic and mutant SOD1-associated ALS. RESULTS We found altered expression of spliceosome components in motor neurones and widespread aberrations of mRNA splicing that specifically affected genes involved in ribonucleotide binding. This was confirmed in TDP-43-depleted NSC34 cells. Fibroblasts with mtTARDBP showed loss of nuclear TDP-43 protein and demonstrated similar changes in splicing and gene expression, which were not present in fibroblasts from patients with sporadic or SOD1-related ALS. CONCLUSION Loss of nuclear TDP-43 is associated with RNA processing abnormalities in ALS motor neurones, patient-derived cells with mtTARDBP, and following artificial TDP-43 depletion, suggesting that splicing dysregulation directly contributes to disease pathogenesis. Key functional pathways affected include those central to RNA metabolism.
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Affiliation(s)
- J Robin Highley
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
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