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Clayton EL, Huggon L, Cousin MA, Mizielinska S. Synaptopathy: presynaptic convergence in frontotemporal dementia and amyotrophic lateral sclerosis. Brain 2024; 147:2289-2307. [PMID: 38451707 PMCID: PMC11224618 DOI: 10.1093/brain/awae074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 02/02/2024] [Accepted: 02/12/2024] [Indexed: 03/09/2024] Open
Abstract
Frontotemporal dementia and amyotrophic lateral sclerosis are common forms of neurodegenerative disease that share overlapping genetics and pathologies. Crucially, no significantly disease-modifying treatments are available for either disease. Identifying the earliest changes that initiate neuronal dysfunction is important for designing effective intervention therapeutics. The genes mutated in genetic forms of frontotemporal dementia and amyotrophic lateral sclerosis have diverse cellular functions, and multiple disease mechanisms have been proposed for both. Identification of a convergent disease mechanism in frontotemporal dementia and amyotrophic lateral sclerosis would focus research for a targetable pathway, which could potentially effectively treat all forms of frontotemporal dementia and amyotrophic lateral sclerosis (both familial and sporadic). Synaptopathies are diseases resulting from physiological dysfunction of synapses, and define the earliest stages in multiple neuronal diseases, with synapse loss a key feature in dementia. At the presynapse, the process of synaptic vesicle recruitment, fusion and recycling is necessary for activity-dependent neurotransmitter release. The unique distal location of the presynaptic terminal means the tight spatio-temporal control of presynaptic homeostasis is dependent on efficient local protein translation and degradation. Recently, numerous publications have shown that mutations associated with frontotemporal dementia and amyotrophic lateral sclerosis present with synaptopathy characterized by presynaptic dysfunction. This review will describe the complex local signalling and membrane trafficking events that occur at the presynapse to facilitate neurotransmission and will summarize recent publications linking frontotemporal dementia/amyotrophic lateral sclerosis genetic mutations to presynaptic function. This evidence indicates that presynaptic synaptopathy is an early and convergent event in frontotemporal dementia and amyotrophic lateral sclerosis and illustrates the need for further research in this area, to identify potential therapeutic targets with the ability to impact this convergent pathomechanism.
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Affiliation(s)
- Emma L Clayton
- UK Dementia Research Institute at King’s College London, London SE5 9RT, UK
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, Maurice Wohl Clinical Neuroscience Institute, London SE5 9RT, UK
| | - Laura Huggon
- UK Dementia Research Institute at King’s College London, London SE5 9RT, UK
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, Maurice Wohl Clinical Neuroscience Institute, London SE5 9RT, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Sarah Mizielinska
- UK Dementia Research Institute at King’s College London, London SE5 9RT, UK
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, Maurice Wohl Clinical Neuroscience Institute, London SE5 9RT, UK
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2
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Milstead RA, Link CD, Xu Z, Hoeffer CA. TDP-43 knockdown in mouse model of ALS leads to dsRNA deposition, gliosis, and neurodegeneration in the spinal cord. Cereb Cortex 2023; 33:5808-5816. [PMID: 36443249 PMCID: PMC10183735 DOI: 10.1093/cercor/bhac461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/28/2022] [Accepted: 10/29/2022] [Indexed: 11/30/2022] Open
Abstract
Transactive response DNA binding protein 43 kilodaltons (TDP-43) is a DNA and RNA binding protein associated with severe neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), primarily affecting motor neurons in the brain and spinal cord. Partial knockdown of TDP-43 expression in a mouse model (the amiR-TDP-43 mice) leads to progressive, age-related motor dysfunction, as observed in ALS patients. Work in Caenorhabditis elegans suggests that TDP-43 dysfunction can lead to deficits in chromatin processing and double-stranded RNA (dsRNA) accumulation, potentially activating the innate immune system and promoting neuroinflammation. To test this hypothesis, we used immunostaining to investigate dsRNA accumulation and other signs of CNS pathology in the spinal cords of amiR-TDP-43 mice. Compared with wild-type controls, TDP-43 knockdown animals show increases in dsRNA deposition in the dorsal and ventral horns of the spinal cord. Additionally, animals with heavy dsRNA expression show markedly increased levels of astrogliosis and microgliosis. Interestingly, areas of high dsRNA expression and microgliosis overlap with regions of heavy neurodegeneration, indicating that activated microglia could contribute to the degeneration of spinal cord neurons. This study suggests that loss of TDP-43 function could contribute to neuropathology by increasing dsRNA deposition and subsequent innate immune system activation.
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Affiliation(s)
- Ryan A Milstead
- Department of Integrative Physiology, University of Colorado, Boulder, Boulder CO 80303
- Institute for Behavioral Genetics, University of Colorado, Boulder, Boulder, CO 80303
| | - Christopher D Link
- Department of Integrative Physiology, University of Colorado, Boulder, Boulder CO 80303
| | - Zuoshang Xu
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, 01655
| | - Charles A Hoeffer
- Department of Integrative Physiology, University of Colorado, Boulder, Boulder CO 80303
- Institute for Behavioral Genetics, University of Colorado, Boulder, Boulder, CO 80303
- Linda Crnic Institute, Anschutz Medical Center, Aurora, CO 80217
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3
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Identification of a novel interaction of FUS and syntaphilin may explain synaptic and mitochondrial abnormalities caused by ALS mutations. Sci Rep 2021; 11:13613. [PMID: 34193962 PMCID: PMC8245466 DOI: 10.1038/s41598-021-93189-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/22/2021] [Indexed: 01/16/2023] Open
Abstract
Aberrantly expressed fused in sarcoma (FUS) is a hallmark of FUS-related amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Wildtype FUS localises to synapses and interacts with mitochondrial proteins while mutations have been shown to cause to pathological changes affecting mitochondria, synapses and the neuromuscular junction (NMJ). This indicates a crucial physiological role for FUS in regulating synaptic and mitochondrial function that is currently poorly understood. In this paper we provide evidence that mislocalised cytoplasmic FUS causes mitochondrial and synaptic changes and that FUS plays a vital role in maintaining neuronal health in vitro and in vivo. Overexpressing mutant FUS altered synaptic numbers and neuronal complexity in both primary neurons and zebrafish models. The degree to which FUS was mislocalised led to differences in the synaptic changes which was mirrored by changes in mitochondrial numbers and transport. Furthermore, we showed that FUS co-localises with the mitochondrial tethering protein Syntaphilin (SNPH), and that mutations in FUS affect this relationship. Finally, we demonstrated mutant FUS led to changes in global protein translation. This localisation between FUS and SNPH could explain the synaptic and mitochondrial defects observed leading to global protein translation defects. Importantly, our results support the ‘gain-of-function’ hypothesis for disease pathogenesis in FUS-related ALS.
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4
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Jiao B, Wang M, Feng H, Bao H, Zhang F, Wu H, Wang J, Tang B, Jin P, Shen L. Downregulation of TOP2 modulates neurodegeneration caused by GGGGCC expanded repeats. Hum Mol Genet 2021; 30:893-901. [PMID: 33749734 DOI: 10.1093/hmg/ddab079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/18/2021] [Accepted: 03/12/2021] [Indexed: 12/13/2022] Open
Abstract
GGGGCC repeats in a non-coding region of the C9orf72 gene have been identified as a major genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. We previously showed that the GGGGCC expanded repeats alone were sufficient to cause neurodegeneration in Drosophila. Recent evidence indicates that GGGGCC expanded repeats can modify various gene transcriptomes. To determine the role of these genes in GGGGCC-mediated neurotoxicity, we screened an established Drosophila model expressing GGGGCC expanded repeats in this study. Our results showed that knockdown of the DNA topoisomerase II (Top2) gene can specifically modulate GGGGCC-associated neurodegeneration of the eye. Furthermore, chemical inhibition of Top2 or siRNA-induced Top2 downregulation could alleviate the GGGGCC-mediated neurotoxicity in Drosophila assessed by eye neurodegeneration and locomotion impairment. By contrast, upregulated Top2 levels were detected in Drosophila strains, and moreover, TOP2A level was also upregulated in Neuro-2a cells expressing GGGGCC expanded repeats, as well as in the brains of Sod1G93A model mice. This indicated that elevated levels of TOP2A may be involved in a pathway common to the pathophysiology of distinct ALS forms. Moreover, through RNA-sequencing, a total of 67 genes, involved in the pathways of intracellular signaling cascades, peripheral nervous system development, and others, were identified as potential targets of TOP2A to modulate GGGGCC-mediated neurodegeneration.
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Affiliation(s)
- Bin Jiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA 30322, USA
- National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Mengli Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Hao Feng
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Han Bao
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Feiran Zhang
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Hao Wu
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Junling Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
- National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
- National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Peng Jin
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Lu Shen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
- National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
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5
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Wang Q, Conlon EG, Manley JL, Rio DC. Widespread intron retention impairs protein homeostasis in C9orf72 ALS brains. Genome Res 2020; 30:1705-1715. [PMID: 33055097 PMCID: PMC7706729 DOI: 10.1101/gr.265298.120] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022]
Abstract
The GGGGCC hexanucleotide expansion in C9orf72 (C9) is the most frequent known cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), yet a clear understanding of how C9 fits into the broader context of ALS/FTD pathology has remained lacking. The repetitive RNA derived from the C9 repeat is known to sequester hnRNPH, a splicing regulator, into insoluble aggregates, resulting in aberrant alternative splicing. Furthermore, hnRNPH insolubility and altered splicing of a robust set of targets have been observed to correlate in C9 and sporadic ALS/FTD patients alike, suggesting that changes along this axis are a core feature of disease pathogenesis. Here, we characterize previously uncategorized RNA splicing defects involving widespread intron retention affecting almost 2000 transcripts in C9ALS/FTD brains exhibiting a high amount of sequestered, insoluble hnRNPH. These intron retention events appear not to alter overall expression levels of the affected transcripts but rather the protein-coding regions. These retained introns affect transcripts in multiple cellular pathways predicted to be involved in C9 as well as sporadic ALS/FTD etiology, including the proteasomal and autophagy systems. The retained intron pre-mRNAs display a number of characteristics, including enrichment of hnRNPH-bound splicing enhancer motifs and a propensity for G-quadruplex (G-Q) formation, linking the defective splicing directly to high amounts of sequestered hnRNPH. Together, our results reveal previously undetected splicing defects in high insoluble hnRNPH-associated C9ALS brains, suggesting a feedback between effective RNA-binding protein dosage and protein quality control in C9, and perhaps all, ALS/FTD.
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Affiliation(s)
- Qingqing Wang
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.,California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, USA
| | - Erin G Conlon
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Donald C Rio
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.,California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, USA
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6
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Mohanta A, Chakrabarti K. Dbr1 functions in mRNA processing, intron turnover and human diseases. Biochimie 2020; 180:134-142. [PMID: 33038423 DOI: 10.1016/j.biochi.2020.10.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 12/29/2022]
Abstract
Pre-mRNA processing and mRNA stability play direct roles in controlling protein abundance in a cell. Before the mRNA can be translated into a protein, the introns in the pre-mRNA transcripts need to be removed by splicing, such that exons can be ligated together and can code for a protein. In this process, the function of the RNA lariat debranching enzyme or Dbr1 provides a rate-limiting step in the intron turnover process and possibly regulating the production of translation competent mRNAs. Surprising new roles of Dbr1 are emerging in cellular metabolism which extends beyond intron turnover processes, ranging from splicing regulation to translational control. In this review, we highlight the importance of the Dbr1 enzyme, its structure and how anomalies in its function could relate to various human diseases.
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Affiliation(s)
- Arundhati Mohanta
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Kausik Chakrabarti
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA.
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7
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Padhi AK, Narain P, Gomes J. Rare Angiogenin and Ribonuclease 4 variants associated with amyotrophic lateral sclerosis exhibit loss-of-function: a comprehensive in silico study. Metab Brain Dis 2019; 34:1661-1677. [PMID: 31368019 DOI: 10.1007/s11011-019-00473-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/18/2019] [Indexed: 12/12/2022]
Abstract
Amyotrophic Lateral Sclerosis (ALS), a debilitating neurodegenerative disorder is related to mutations in a number of genes, and certain genes of the Ribonuclease (RNASE) superfamily trigger ALS more frequently. Even though missense mutations in Angiogenin (ANG) and Ribonuclease 4 (RNASE4) have been previously shown to cause ALS through loss-of-function mechanisms, understanding the role of rare variants with a plausible explanation of their functional loss mechanisms is an important mission. The study aims to understand if any of the rare ANG and RNASE4 variants catalogued in Project MinE consortium caused ALS due to loss of ribonucleolytic or nuclear translocation or both these activities. Several in silico analyses in combination with extensive molecular dynamics (MD) simulations were performed on wild-type ANG and RNASE4, along with six rare variants (T11S-ANG, R122H-ANG, D2E-RNASE4, N26K-RNASE4, T79A-RNASE4 and G119S-RNASE4) to study the structural and dynamic changes in the catalytic triad and nuclear localization signal residues responsible for ribonucleolytic and nuclear translocation activities respectively. Our comprehensive analyses comprising 1.2 μs simulations with a focus on physicochemical, structural and dynamic properties reveal that T11S-ANG, N26K-RNASE4 and T79A-RNASE4 variants would result in loss of ribonucleolytic activity due to conformational switching of catalytic His114 and His116 respectively but none of the variants would lose their nuclear translocation activity. Our study not only highlights the importance of rare variants but also demonstrates that elucidating the structure-function relationship of mutant effectors is crucial to gain insights into ALS pathophysiology and in developing effective therapeutics.
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Affiliation(s)
- Aditya K Padhi
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
- Laboratory for Structural Bioinformatics, Field for Structural Molecular Biology, Centre for Biosystems Dynamics Research, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan.
| | - Priyam Narain
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
| | - James Gomes
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
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8
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So E, Mitchell JC, Memmi C, Chennell G, Vizcay-Barrena G, Allison L, Shaw CE, Vance C. Mitochondrial abnormalities and disruption of the neuromuscular junction precede the clinical phenotype and motor neuron loss in hFUSWT transgenic mice. Hum Mol Genet 2019; 27:463-474. [PMID: 29194538 PMCID: PMC5886082 DOI: 10.1093/hmg/ddx415] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/26/2017] [Indexed: 11/16/2022] Open
Abstract
FUS (fused in sarcoma) mislocalization and cytoplasmic aggregation are hallmark pathologies in FUS-related amyotrophic lateral sclerosis and frontotemporal dementia. Many of the mechanistic hypotheses have focused on a loss of nuclear function in the FUS-opathies, implicating dysregulated RNA transcription and splicing in driving neurodegeneration. Recent studies describe an additional somato-dendritic localization for FUS in the cerebral cortex implying a regulatory role in mRNA transport and local translation at the synapse. Here, we report that FUS is also abundant at the pre-synaptic terminal of the neuromuscular junction (NMJ), suggesting an important function for this protein at peripheral synapses. We have previously reported dose and age-dependent motor neuron degeneration in transgenic mice overexpressing human wild-type FUS, resulting in a motor phenotype detected by ∼28 days and death by ∼100 days. Now, we report the earliest structural events using electron microscopy and quantitative immunohistochemistry. Mitochondrial abnormalities in the pre-synaptic motor nerve terminals are detected at postnatal day 6, which are more pronounced at P15 and accompanied by a loss of synaptic vesicles and synaptophysin protein coupled with NMJs of a smaller size at a time when there is no detectable motor neuron loss. These changes occur in the presence of abundant FUS and support a peripheral toxic gain of function. This appearance is typical of a ‘dying-back’ axonopathy, with the earliest manifestation being mitochondrial disruption. These findings support our hypothesis that FUS has an important function at the NMJ, and challenge the ‘loss of nuclear function’ hypothesis for disease pathogenesis in the FUS-opathies.
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Affiliation(s)
- Eva So
- Department of Basic and Clinical Neuroscience
| | | | | | - George Chennell
- Department of Basic and Clinical Neuroscience.,Wohl Cellular Imaging Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Denmark Hill, London SE5 8AF, UK
| | - Gema Vizcay-Barrena
- Centre for Ultrastructural Imaging, King's College London, New Hunts House, Guy's Campus, London SE1 1UL, UK
| | - Leanne Allison
- Centre for Ultrastructural Imaging, King's College London, New Hunts House, Guy's Campus, London SE1 1UL, UK
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9
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A molecular dynamics based investigation reveals the role of rare Ribonuclease 4 variants in amyotrophic lateral sclerosis susceptibility. Mutat Res 2018; 813:1-12. [PMID: 30544007 DOI: 10.1016/j.mrfmmm.2018.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 11/28/2018] [Indexed: 12/12/2022]
Abstract
Missense mutations in certain genes of the Ribonuclease (RNASE) superfamily cause amyotrophic lateral sclerosis (ALS) through loss of either ribonucleolytic or nuclear translocation or both of these activities. While rare ANG/RNASE5 variants have been previously shown to be ALS causative, it is not yet known if any of the reported rare RNASE4 variants can also trigger ALS. The study aims to understand whether rare variants of RNASE4 can manifest ALS through similar loss-of-function mechanisms. Molecular dynamics (MD) simulations were performed on wild-type and all reported rare RNASE4 variants to study the structural and dynamic changes in the catalytic triad and nuclear localization signal residues responsible for ribonucleolytic and nuclear translocation activities respectively. Our systematic study comprising a total of 2.1 μs MD simulations reveal that three rare variants M29I, H72P and R95W would lose their ribonucleolytic activity as a result of conformational alteration of catalytic residue His116, and the R31T and R32W variants would lose their nuclear translocation ability due to local folding and reduced solvent accessibility of 30QRR32 residues. Our results show that five among the 20 known rare variants in RNASE4 (M29I, H72P, R95W, R31T and R32W) are possibly deleterious and may manifest ALS due to loss-of-function mechanisms. Overall, this is the first study to demonstrate that although rare and not yet clinically correlated, certain rare RNASE4 variants could cause ALS due to their loss-of-function characteristics and highlights the need to discover novel RNASE variants for a comprehensive understanding of structure-function-disease relationships and design effective therapeutics.
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Padhi AK, Narain P, Dave U, Satija R, Patir A, Gomes J. Insights into the role of ribonuclease 4 polymorphisms in amyotrophic lateral sclerosis. J Biomol Struct Dyn 2018; 37:116-130. [PMID: 29279004 DOI: 10.1080/07391102.2017.1419147] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Mutations in certain genes of the Ribonuclease (RNASE) superfamily can cause amyotrophic lateral sclerosis (ALS) through altered RNA processing mechanisms. About 30 of these missense mutations in RNASE5/ANG gene have already been reported in ALS patients. In another gene of the ribonuclease superfamily, ribonuclease 4 (RNASE4), missense mutations and single nucleotide polymorphisms have been identified in patients suffering from ALS. However, their plausible molecular mechanisms of association with ALS are not known. Here, we present the molecular mechanisms of RNASE4 polymorphisms with ALS using all-atom molecular dynamics (MD) simulations followed by functional assay experiments. As most ALS causing mutations in RNASE superfamily proteins affect either the ribonucleolytic or nuclear translocation activity, we examined these functional properties of wild-type and known RNASE4 variants, R10W, A98V, E48D and V75I, using MD simulations. Our simulation predicted that these variants would retain nuclear translocation activity and that E48D would exhibit loss of ribonucleolytic activity, which was subsequently validated by ribonucleolytic assay. Our results give a mechanistic insight into the association of RNASE4 polymorphisms with ALS and show that E48D-RNASE4 would probably be deleterious and cause ALS in individuals harbouring this polymorphism.
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Affiliation(s)
- Aditya K Padhi
- a Kusuma School of Biological Sciences , Indian Institute of Technology Delhi , Block 1A, Room No. 307, Hauz Khas, New Delhi 110016 , India
| | - Priyam Narain
- a Kusuma School of Biological Sciences , Indian Institute of Technology Delhi , Block 1A, Room No. 307, Hauz Khas, New Delhi 110016 , India
| | - Upma Dave
- a Kusuma School of Biological Sciences , Indian Institute of Technology Delhi , Block 1A, Room No. 307, Hauz Khas, New Delhi 110016 , India
| | - Rohit Satija
- a Kusuma School of Biological Sciences , Indian Institute of Technology Delhi , Block 1A, Room No. 307, Hauz Khas, New Delhi 110016 , India
| | - Anirudh Patir
- a Kusuma School of Biological Sciences , Indian Institute of Technology Delhi , Block 1A, Room No. 307, Hauz Khas, New Delhi 110016 , India
| | - James Gomes
- a Kusuma School of Biological Sciences , Indian Institute of Technology Delhi , Block 1A, Room No. 307, Hauz Khas, New Delhi 110016 , India
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11
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Gu J, Wu F, Xu W, Shi J, Hu W, Jin N, Qian W, Wang X, Iqbal K, Gong CX, Liu F. TDP-43 suppresses tau expression via promoting its mRNA instability. Nucleic Acids Res 2017; 45:6177-6193. [PMID: 28335005 PMCID: PMC5449590 DOI: 10.1093/nar/gkx175] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 03/06/2017] [Indexed: 12/12/2022] Open
Abstract
In the brains of individuals with Alzheimer's disease (AD) and chronic traumatic encephalopathy, tau pathology is accompanied usually by intracellular aggregation of transactive response DNA-binding protein 43 (TDP-43). However, the role of TDP-43 in tau pathogenesis is not understood. Here, we investigated the role of TDP-43 in tau expression in vitro and in vivo. We found that TDP-43 suppressed tau expression by promoting its mRNA instability through the UG repeats of its 3΄-untranslated region (3΄-UTR). The C-terminal region of TDP-43 was required for this function. Neurodegenerative diseases-causing TDP-43 mutations affected tau mRNA instability differentially, in that some promoted and others did not significantly affect tau mRNA instability. The expression levels of tau and TDP-43 were inverse in the frontal cortex and the cerebellum. Accompanied with cytoplasmic accumulation of TDP-43, tau expression was elevated in TDP-43M337V transgenic mouse brains. The level of TDP-43, which is decreased in AD brains, was found to correlate negatively with the tau level in human brain. Our findings indicate that TDP-43 suppresses tau expression by promoting the instability of its mRNA. Down-regulation of TDP-43 may be involved in the tau pathology in AD and related neurodegenerative disorders.
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Affiliation(s)
- Jianlan Gu
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
- Department of Biochemistry and molecular biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Feng Wu
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Wen Xu
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Jianhua Shi
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Wen Hu
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Nana Jin
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Wei Qian
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Biochemistry and molecular biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Xinglong Wang
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Khalid Iqbal
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Cheng-Xin Gong
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Fei Liu
- Key Laboratory of Neuroregeneration of Jiangsu and ministry of education and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
- To whom correspondence should be addressed. Tel: +1 718 494 5263; Fax: +1 718 494 1080;
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12
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Donnelly CJ, Grima JC, Sattler R. Aberrant RNA homeostasis in amyotrophic lateral sclerosis: potential for new therapeutic targets? Neurodegener Dis Manag 2015; 4:417-37. [PMID: 25531686 DOI: 10.2217/nmt.14.36] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive motor neuron degeneration. The disease pathogenesis is multifaceted in that multiple cellular and molecular pathways have been identified as contributors to the disease progression. Consequently, numerous therapeutic targets have been pursued for clinical development, unfortunately with little success. The recent discovery of mutations in RNA modulating genes such as TARDBP/TDP-43, FUS/TLS or C9ORF72 changed our understanding of neurodegenerative mechanisms in ALS and introduced the role of dysfunctional RNA processing as a significant contributor to disease pathogenesis. This article discusses the latest findings on such RNA toxicity pathways in ALS and potential novel therapeutic approaches.
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Affiliation(s)
- Christopher J Donnelly
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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13
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Coady TH, Manley JL. ALS mutations in TLS/FUS disrupt target gene expression. Genes Dev 2015; 29:1696-706. [PMID: 26251528 PMCID: PMC4561479 DOI: 10.1101/gad.267286.115] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/22/2015] [Indexed: 12/12/2022]
Abstract
In this study, Coadey et al. investigated how mutations in the RNA/DNA-binding protein TLS/FUS (FUS), caused by ALS, affect target gene expression. They used several FUS derivatives with ALS mutations and showed that FUS-containing aggregates can alter gene expression by a toxic gain-of-function mechanism. These findings establish that ALS mutations in FUS can strongly impact target gene expression. Amyotrophic lateral sclerosis (ALS) is caused by mutations in a number of genes, including the gene encoding the RNA/DNA-binding protein translocated in liposarcoma or fused in sarcoma (TLS/FUS or FUS). Previously, we identified a number of FUS target genes, among them MECP2. To investigate how ALS mutations in FUS might impact target gene expression, we examined the effects of several FUS derivatives harboring ALS mutations, such as R521C (FUSC), on MECP2 expression in transfected human U87 cells. Strikingly, FUSC and other mutants not only altered MECP2 alternative splicing but also markedly increased mRNA abundance, which we show resulted from sharply elevated stability. Paradoxically, however, MeCP2 protein levels were significantly reduced in cells expressing ALS mutant derivatives. Providing a parsimonious explanation for these results, biochemical fractionation and in vivo localization studies revealed that MECP2 mRNA colocalized with cytoplasmic FUSC in insoluble aggregates, which are characteristic of ALS mutant proteins. Together, our results establish that ALS mutations in FUS can strongly impact target gene expression, reflecting a dominant effect of FUS-containing aggregates.
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Affiliation(s)
- Tristan H Coady
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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14
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Fontana F, Siva K, Denti MA. A network of RNA and protein interactions in Fronto Temporal Dementia. Front Mol Neurosci 2015; 8:9. [PMID: 25852467 PMCID: PMC4365750 DOI: 10.3389/fnmol.2015.00009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Accepted: 02/25/2015] [Indexed: 12/12/2022] Open
Abstract
Frontotemporal dementia (FTD) is a neurodegenerative disorder characterized by degeneration of the fronto temporal lobes and abnormal protein inclusions. It exhibits a broad clinicopathological spectrum and has been linked to mutations in seven different genes. We will provide a picture, which connects the products of these genes, albeit diverse in nature and function, in a network. Despite the paucity of information available for some of these genes, we believe that RNA processing and post-transcriptional regulation of gene expression might constitute a common theme in the network. Recent studies have unraveled the role of mutations affecting the functions of RNA binding proteins and regulation of microRNAs. This review will combine all the recent findings on genes involved in the pathogenesis of FTD, highlighting the importance of a common network of interactions in order to study and decipher the heterogeneous clinical manifestations associated with FTD. This approach could be helpful for the research of potential therapeutic strategies.
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Affiliation(s)
- Francesca Fontana
- Laboratory of RNA Biology and Biotechnology, Centre for Integrative Biology, University of TrentoTrento, Italy
| | - Kavitha Siva
- Laboratory of RNA Biology and Biotechnology, Centre for Integrative Biology, University of TrentoTrento, Italy
| | - Michela A. Denti
- Laboratory of RNA Biology and Biotechnology, Centre for Integrative Biology, University of TrentoTrento, Italy
- CNR, Institute of NeurosciencePadua, Italy
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15
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Palomo GM, Manfredi G. Exploring new pathways of neurodegeneration in ALS: the role of mitochondria quality control. Brain Res 2014; 1607:36-46. [PMID: 25301687 DOI: 10.1016/j.brainres.2014.09.065] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 09/26/2014] [Accepted: 09/27/2014] [Indexed: 12/11/2022]
Abstract
Neuronal cells are highly dependent on mitochondria, and mitochondrial dysfunction is associated with neurodegenerative diseases. As perturbed mitochondrial function renders neurons extremely sensitive to a wide variety of insults, such as oxidative stress and bioenergetic defects, mitochondrial defects can profoundly affect neuronal fate. Several studies have linked ALS with mitochondrial dysfunction, stemming from observations of mitochondrial abnormalities, both in patients and in cellular and mouse models of familial forms of ALS. Mitochondrial changes have been thoroughly investigated in mutants of superoxide dismutase 1 (SOD1), one of the most common causes of familial ALS, for which excellent cellular and animal models are available, but recently evidence is emerging also in other forms of ALS, both familial and sporadic. Mitochondrial defects in ALS involve many critical physiopathological processes, from defective bioenergetics to abnormal calcium homeostasis, altered morphology and impaired trafficking. In this review, we summarize established evidence of mitochondrial dysfunction in ALS, especially in SOD1 mutant models of familial ALS. The main focus of the review is on defective mitochondrial quality control (MQC) in ALS. MQC operates at multiple levels to clear damaged proteins through proteostasis and to eliminate irreparably damaged organelles through mitophagy. However, since ALS motor neurons progressively accumulate damaged mitochondria, it is plausible that the MQC is ineffective or overwhelmed by excessive workload imposed by the chronic and extensive mitochondrial damage. This article is part of a Special Issue entitled ALS complex pathogenesis.
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Affiliation(s)
- Gloria M Palomo
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, United States
| | - Giovanni Manfredi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, United States.
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16
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Tibshirani M, Tradewell ML, Mattina KR, Minotti S, Yang W, Zhou H, Strong MJ, Hayward LJ, Durham HD. Cytoplasmic sequestration of FUS/TLS associated with ALS alters histone marks through loss of nuclear protein arginine methyltransferase 1. Hum Mol Genet 2014; 24:773-86. [PMID: 25274782 DOI: 10.1093/hmg/ddu494] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Mutations in the RNA-binding protein FUS/TLS (FUS) have been linked to the neurodegenerative disease amyotrophic lateral sclerosis (ALS). Although predominantly nuclear, this heterogenous nuclear ribonuclear protein (hnRNP) has multiple functions in RNA processing including intracellular trafficking. In ALS, mutant or wild-type (WT) FUS can form neuronal cytoplasmic inclusions. Asymmetric arginine methylation of FUS by the class 1 arginine methyltransferase, protein arginine methyltransferase 1 (PRMT1), regulates nucleocytoplasmic shuttling of FUS. In motor neurons of primary spinal cord cultures, redistribution of endogenous mouse and that of ectopically expressed WT or mutant human FUS to the cytoplasm led to nuclear depletion of PRMT1, abrogating methylation of its nuclear substrates. Specifically, hypomethylation of arginine 3 of histone 4 resulted in decreased acetylation of lysine 9/14 of histone 3 and transcriptional repression. Distribution of neuronal PRMT1 coincident with FUS also was detected in vivo in the spinal cord of FUS(R495X) transgenic mice. However, nuclear PRMT1 was not stable postmortem obviating meaningful evaluation of ALS autopsy cases. This study provides evidence for loss of PRMT1 function as a consequence of cytoplasmic accumulation of FUS in the pathogenesis of ALS, including changes in the histone code regulating gene transcription.
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Affiliation(s)
- Michael Tibshirani
- Montreal Neurological Institute and Department of Neurology/Neurosurgery, McGill University, Montreal, Quebec, Canada H3A 2B4
| | - Miranda L Tradewell
- Montreal Neurological Institute and Department of Neurology/Neurosurgery, McGill University, Montreal, Quebec, Canada H3A 2B4
| | - Katie R Mattina
- Montreal Neurological Institute and Department of Neurology/Neurosurgery, McGill University, Montreal, Quebec, Canada H3A 2B4
| | - Sandra Minotti
- Montreal Neurological Institute and Department of Neurology/Neurosurgery, McGill University, Montreal, Quebec, Canada H3A 2B4
| | - Wencheng Yang
- Robarts Research Institute, Western University, London, Ontario, Canada N6A 5C1 and
| | - Hongru Zhou
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Michael J Strong
- Robarts Research Institute, Western University, London, Ontario, Canada N6A 5C1 and
| | - Lawrence J Hayward
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Heather D Durham
- Montreal Neurological Institute and Department of Neurology/Neurosurgery, McGill University, Montreal, Quebec, Canada H3A 2B4
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17
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van Blitterswijk M, Mullen B, Wojtas A, Heckman MG, Diehl NN, Baker MC, DeJesus-Hernandez M, Brown PH, Murray ME, Hsiung GYR, Stewart H, Karydas AM, Finger E, Kertesz A, Bigio EH, Weintraub S, Mesulam M, Hatanpaa KJ, White CL, Neumann M, Strong MJ, Beach TG, Wszolek ZK, Lippa C, Caselli R, Petrucelli L, Josephs KA, Parisi JE, Knopman DS, Petersen RC, Mackenzie IR, Seeley WW, Grinberg LT, Miller BL, Boylan KB, Graff-Radford NR, Boeve BF, Dickson DW, Rademakers R. Genetic modifiers in carriers of repeat expansions in the C9ORF72 gene. Mol Neurodegener 2014; 9:38. [PMID: 25239657 PMCID: PMC4190282 DOI: 10.1186/1750-1326-9-38] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 08/29/2014] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Hexanucleotide repeat expansions in chromosome 9 open reading frame 72 (C9ORF72) are causative for frontotemporal dementia (FTD) and motor neuron disease (MND). Substantial phenotypic heterogeneity has been described in patients with these expansions. We set out to identify genetic modifiers of disease risk, age at onset, and survival after onset that may contribute to this clinical variability. RESULTS We examined a cohort of 330 C9ORF72 expansion carriers and 374 controls. In these individuals, we assessed variants previously implicated in FTD and/or MND; 36 variants were included in our analysis. After adjustment for multiple testing, our analysis revealed three variants significantly associated with age at onset (rs7018487 [UBAP1; p-value = 0.003], rs6052771 [PRNP; p-value = 0.003], and rs7403881 [MT-Ie; p-value = 0.003]), and six variants significantly associated with survival after onset (rs5848 [GRN; p-value = 0.001], rs7403881 [MT-Ie; p-value = 0.001], rs13268953 [ELP3; p-value = 0.003], the epsilon 4 allele [APOE; p-value = 0.004], rs12608932 [UNC13A; p-value = 0.003], and rs1800435 [ALAD; p-value = 0.003]). CONCLUSIONS Variants identified through this study were previously reported to be involved in FTD and/or MND, but we are the first to describe their effects as potential disease modifiers in the presence of a clear pathogenic mutation (i.e. C9ORF72 repeat expansion). Although validation of our findings is necessary, these variants highlight the importance of protein degradation, antioxidant defense and RNA-processing pathways, and additionally, they are promising targets for the development of therapeutic strategies and prognostic tests.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Rosa Rademakers
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
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18
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Yamashita M, Nonaka T, Hirai S, Miwa A, Okado H, Arai T, Hosokawa M, Akiyama H, Hasegawa M. Distinct pathways leading to TDP-43-induced cellular dysfunctions. Hum Mol Genet 2014; 23:4345-56. [PMID: 24698978 DOI: 10.1093/hmg/ddu152] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
TAR DNA-binding protein of 43 kDa (TDP-43) is the major component protein of inclusions found in brains of patients with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-TDP). However, the molecular mechanisms by which TDP-43 causes neuronal dysfunction and death remain unknown. Here, we report distinct cytotoxic effects of full-length TDP-43 (FL-TDP) and its C-terminal fragment (CTF) in SH-SY5Y cells. When FL-TDP was overexpressed in the cells using a lentiviral system, exogenous TDP-43, like endogenous TDP-43, was expressed mainly in nuclei of cells without any intracellular inclusions. However, these cells showed striking cell death, caspase activation and growth arrest at G2/M phase, indicating that even simple overexpression of TDP-43 induces cellular dysfunctions leading to apoptosis. On the other hand, cells expressing TDP-43 CTF showed cytoplasmic aggregates but without significant cell death, compared with cells expressing FL-TDP. Confocal microscopic analyses revealed that RNA polymerase II (RNA pol II) and several transcription factors, such as specificity protein 1 and cAMP-response-element-binding protein, were co-localized with the aggregates of TDP-43 CTF, suggesting that sequestration of these factors into TDP-43 aggregates caused transcriptional dysregulation. Indeed, accumulation of RNA pol II at TDP-43 inclusions was detected in brains of patients with FTLD-TDP. Furthermore, apoptosis was not observed in affected neurons of FTLD-TDP brains containing phosphorylated and aggregated TDP-43 pathology. Our results suggest that different pathways of TDP-43-induced cellular dysfunction may contribute to the degeneration cascades involved in the onset of ALS and FTLD-TDP.
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Affiliation(s)
| | | | - Shinobu Hirai
- Department of Brain Development and Neural Regeneration and
| | - Akiko Miwa
- Department of Brain Development and Neural Regeneration and
| | - Haruo Okado
- Department of Brain Development and Neural Regeneration and
| | - Tetsuaki Arai
- Department of Neuropsychiatry, Division of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Masato Hosokawa
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Haruhiko Akiyama
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
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19
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Barmada SJ, Serio A, Arjun A, Bilican B, Daub A, Ando DM, Tsvetkov A, Pleiss M, Li X, Peisach D, Shaw C, Chandran S, Finkbeiner S. Autophagy induction enhances TDP43 turnover and survival in neuronal ALS models. Nat Chem Biol 2014; 10:677-85. [PMID: 24974230 PMCID: PMC4106236 DOI: 10.1038/nchembio.1563] [Citation(s) in RCA: 331] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 05/19/2014] [Indexed: 12/13/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) have distinct clinical features but a common pathology--cytoplasmic inclusions rich in transactive response element DNA-binding protein of 43 kDa (TDP43). Rare TDP43 mutations cause ALS or FTD, but abnormal TDP43 levels and localization may cause disease even if TDP43 lacks a mutation. Here we show that individual neurons vary in their ability to clear TDP43 and are exquisitely sensitive to TDP43 levels. To measure TDP43 clearance, we developed and validated a single-cell optical method that overcomes the confounding effects of aggregation and toxicity and discovered that pathogenic mutations shorten TDP43 half-life. New compounds that stimulate autophagy improved TDP43 clearance and localization and enhanced survival in primary murine neurons and in human stem cell-derived neurons and astrocytes harboring mutant TDP43. These findings indicate that the levels and localization of TDP43 critically determine neurotoxicity and show that autophagy induction mitigates neurodegeneration by acting directly on TDP43 clearance.
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Affiliation(s)
- Sami J. Barmada
- Gladstone Institute of Neurologic Disease, San Francisco, California, 94158
- Department of Neurology, University of California, San Francisco, Medical Center, San Francisco, California 94143
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Andrea Serio
- Euan MacDonald Centre for Motor Neurone Disease Research, and Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, UK
| | - Arpana Arjun
- Gladstone Institute of Neurologic Disease, San Francisco, California, 94158
| | - Bilada Bilican
- Euan MacDonald Centre for Motor Neurone Disease Research, and Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, UK
| | - Aaron Daub
- Gladstone Institute of Neurologic Disease, San Francisco, California, 94158
| | - D. Michael Ando
- Gladstone Institute of Neurologic Disease, San Francisco, California, 94158
- Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
| | - Andrey Tsvetkov
- Gladstone Institute of Neurologic Disease, San Francisco, California, 94158
| | - Michael Pleiss
- Keck Program in Brain Cell Engineering, Gladstone Institutes, San Francisco, California, 94158
| | - Xingli Li
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Daniel Peisach
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Christopher Shaw
- Institute of Psychiatry, Medical Research Council Centre for Neurodegeneration Research, King’s College London, London, UK
| | - Siddharthan Chandran
- Euan MacDonald Centre for Motor Neurone Disease Research, and Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, UK
| | - Steven Finkbeiner
- Gladstone Institute of Neurologic Disease, San Francisco, California, 94158
- Department of Neurology, University of California, San Francisco, Medical Center, San Francisco, California 94143
- Department of Physiology, University of California, San Francisco, Medical Center, San Francisco, California 94143
- Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
- Keck Program in Brain Cell Engineering, Gladstone Institutes, San Francisco, California, 94158
- Taube-Koret Center for Neurodegenerative Disease Research, Hellman Family Foundation Alzheimer’s Disease Research Program, and Roddenberry Stem Cell Program, San Francisco, California 94158
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20
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Sama RRK, Ward CL, Bosco DA. Functions of FUS/TLS from DNA repair to stress response: implications for ALS. ASN Neuro 2014; 6:6/4/1759091414544472. [PMID: 25289647 PMCID: PMC4189536 DOI: 10.1177/1759091414544472] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Fused in sarcoma/translocated in liposarcoma (FUS/TLS or FUS) is a multifunctional DNA-/RNA-binding protein that is involved in a variety of cellular functions including transcription, protein translation, RNA splicing, and transport. FUS was initially identified as a fusion oncoprotein, and thus, the early literature focused on the role of FUS in cancer. With the recent discoveries revealing the role of FUS in neurodegenerative diseases, namely amyotrophic lateral sclerosis and frontotemporal lobar degeneration, there has been a renewed interest in elucidating the normal functions of FUS. It is not clear which, if any, endogenous functions of FUS are involved in disease pathogenesis. Here, we review what is currently known regarding the normal functions of FUS with an emphasis on DNA damage repair, RNA processing, and cellular stress response. Further, we discuss how ALS-causing mutations can potentially alter the role of FUS in these pathways, thereby contributing to disease pathogenesis.
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Affiliation(s)
| | - Catherine L Ward
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Daryl A Bosco
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
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21
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Droppelmann CA, Campos-Melo D, Ishtiaq M, Volkening K, Strong MJ. RNA metabolism in ALS: When normal processes become pathological. Amyotroph Lateral Scler Frontotemporal Degener 2014; 15:321-36. [DOI: 10.3109/21678421.2014.881377] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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22
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Bucher T, Colle MA, Wakeling E, Dubreil L, Fyfe J, Briot-Nivard D, Maquigneau M, Raoul S, Cherel Y, Astord S, Duque S, Marais T, Voit T, Moullier P, Barkats M, Joussemet B. scAAV9 intracisternal delivery results in efficient gene transfer to the central nervous system of a feline model of motor neuron disease. Hum Gene Ther 2014; 24:670-82. [PMID: 23799774 DOI: 10.1089/hum.2012.218] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
On the basis of previous studies suggesting that vascular endothelial growth factor (VEGF) could protect motor neurons from degeneration, adeno-associated virus vectors (serotypes 1 and 9) encoding VEGF (AAV.vegf) were administered in a limb-expression 1 (LIX1)-deficient cat-a large animal model of lower motor neuron disease-using three different delivery routes to the central nervous system. AAV.vegf vectors were injected into the motor cortex via intracerebral administration, into the cisterna magna, or intravenously in young adult cats. Intracerebral injections resulted in detectable transgene DNA and transcripts throughout the spinal cord, confirming anterograde transport of AAV via the corticospinal pathway. However, such strategy led to low levels of VEGF expression in the spinal cord. Similar AAV doses injected intravenously resulted also in poor spinal cord transduction. In contrast, intracisternal delivery of AAV exhibited long-term transduction and high levels of VEGF expression in the entire spinal cord, yet with no detectable therapeutic clinical benefit in LIX1-deficient animals. Altogether, we demonstrate (i) that intracisternal delivery is an effective AAV delivery route resulting in high transduction of the entire spinal cord, associated with little to no off-target gene expression, and (ii) that in a LIX1-deficient cat model, however, VEGF expressed at high levels in the spinal cord has no beneficial impact on the disease course.
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Affiliation(s)
- Thomas Bucher
- INSERM UMR1089, Institut de Recherche Thérapeutique 1, Université de Nantes, 44007 Nantes Cedex 01, France
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23
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Azuma Y, Tokuda T, Shimamura M, Kyotani A, Sasayama H, Yoshida T, Mizuta I, Mizuno T, Nakagawa M, Fujikake N, Ueyama M, Nagai Y, Yamaguchi M. Identification of ter94, Drosophila VCP, as a strong modulator of motor neuron degeneration induced by knockdown of Caz, Drosophila FUS. Hum Mol Genet 2014; 23:3467-80. [PMID: 24497576 DOI: 10.1093/hmg/ddu055] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In humans, mutations in the fused in sarcoma (FUS) gene have been identified in sporadic and familial forms of amyotrophic lateral sclerosis (ALS). Cabeza (Caz) is the Drosophila ortholog of human FUS. Previously, we established Drosophila models of ALS harboring Caz-knockdown. These flies develop locomotive deficits and anatomical defects in motoneurons (MNs) at neuromuscular junctions; these phenotypes indicate that loss of physiological FUS functions in the nucleus can cause MN degeneration similar to that seen in FUS-related ALS. Here, we aimed to explore molecules that affect these ALS-like phenotypes of our Drosophila models with eye-specific and neuron-specific Caz-knockdown. We examined several previously reported ALS-related genes and found genetic links between Caz and ter94, the Drosophila ortholog of human Valosin-containing protein (VCP). Genetic crossing the strongest loss-of-function allele of ter94 with Caz-knockdown strongly enhanced the rough-eye phenotype and the MN-degeneration phenotype caused by Caz-knockdown. Conversely, the overexpression of wild-type ter94 in the background of Caz-knockdown remarkably suppressed those phenotypes. Our data demonstrated that expression levels of Drosophila VCP ortholog dramatically modified the phenotypes caused by Caz-knockdown in either direction, exacerbation or remission. Our results indicate that therapeutic agents that up-regulate the function of human VCP could modify the pathogenic processes that lead to the degeneration of MNs in ALS.
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Affiliation(s)
| | - Takahiko Tokuda
- Department of Neurology and Department of Molecular Pathobiology of Brain Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Mai Shimamura
- Department of Applied Biology and Insect Biomedical Research Center, Kyoto Institute of Technology, Hashikami-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Akane Kyotani
- Department of Applied Biology and Insect Biomedical Research Center, Kyoto Institute of Technology, Hashikami-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | | | | | | | | | | | - Nobuhiro Fujikake
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Morio Ueyama
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Yoshitaka Nagai
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Masamitsu Yamaguchi
- Department of Applied Biology and Insect Biomedical Research Center, Kyoto Institute of Technology, Hashikami-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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24
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van Blitterswijk M, Baker MC, Bieniek KF, Knopman DS, Josephs KA, Boeve B, Caselli R, Wszolek ZK, Petersen R, Graff-Radford NR, Boylan KB, Dickson DW, Rademakers R. Profilin-1 mutations are rare in patients with amyotrophic lateral sclerosis and frontotemporal dementia. Amyotroph Lateral Scler Frontotemporal Degener 2013; 14:463-9. [PMID: 23634771 PMCID: PMC3923463 DOI: 10.3109/21678421.2013.787630] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mutations in profilin-1 (PFN1) have recently been identified in patients with amyotrophic lateral sclerosis (ALS). Because of the considerable overlap between ALS and the common subtype of frontotemporal dementia, which is characterized by transactive response DNA-binding protein 43 pathology (FTLD-TDP), we tested cohorts of ALS and FTLD-TDP patients for PFN1 mutations. DNA was obtained from 342 ALS patients and 141 FTLD-TDP patients at our outpatient clinic and brain bank for neurodegenerative diseases at the Mayo Clinic Florida, Jacksonville, USA. We screened these patients for mutations in coding regions of PFN1 by Sanger sequencing. Subsequently, we used TaqMan genotyping assays to investigate the identified variant in 1167 control subjects. From the results, one variant, p.E117G, was detected in one ALS patient, one FTLD-TDP patient, and two control subjects. The mutation frequency of patients versus control subjects was not significantly different (p-value = 0.36). Moreover, PFN1 and TDP-43 staining of autopsy material did not differ between patients with or without this variant. In conclusion, the p.E117G variant appears to represent a benign polymorphism. PFN1 mutations, in general, are rare in ALS and FTLD-TDP patients.
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Affiliation(s)
| | | | | | | | | | - Bradley Boeve
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | | | | | | | | | | | | | - Rosa Rademakers
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
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Vance C, Scotter EL, Nishimura AL, Troakes C, Mitchell JC, Kathe C, Urwin H, Manser C, Miller CC, Hortobágyi T, Dragunow M, Rogelj B, Shaw CE. ALS mutant FUS disrupts nuclear localization and sequesters wild-type FUS within cytoplasmic stress granules. Hum Mol Genet 2013; 22:2676-88. [PMID: 23474818 PMCID: PMC3674807 DOI: 10.1093/hmg/ddt117] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/05/2013] [Indexed: 12/12/2022] Open
Abstract
Mutations in the gene encoding Fused in Sarcoma (FUS) cause amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder. FUS is a predominantly nuclear DNA- and RNA-binding protein that is involved in RNA processing. Large FUS-immunoreactive inclusions fill the perikaryon of surviving motor neurons of ALS patients carrying mutations at post-mortem. This sequestration of FUS is predicted to disrupt RNA processing and initiate neurodegeneration. Here, we demonstrate that C-terminal ALS mutations disrupt the nuclear localizing signal (NLS) of FUS resulting in cytoplasmic accumulation in transfected cells and patient fibroblasts. FUS mislocalization is rescued by the addition of the wild-type FUS NLS to mutant proteins. We also show that oxidative stress recruits mutant FUS to cytoplasmic stress granules where it is able to bind and sequester wild-type FUS. While FUS interacts with itself directly by protein-protein interaction, the recruitment of FUS to stress granules and interaction with PABP are RNA dependent. These findings support a two-hit hypothesis, whereby cytoplasmic mislocalization of FUS protein, followed by cellular stress, contributes to the formation of cytoplasmic aggregates that may sequester FUS, disrupt RNA processing and initiate motor neuron degeneration.
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Affiliation(s)
| | | | | | | | | | | | | | - Catherine Manser
- Department of Neuroscience, King's College London, Centre for Neurodegeneration Research, Institute of Psychiatry, London SE5 8AF, UK
| | - Christopher C. Miller
- Department of Clinical Neuroscience and
- Department of Neuroscience, King's College London, Centre for Neurodegeneration Research, Institute of Psychiatry, London SE5 8AF, UK
| | | | - Mike Dragunow
- Faculty of Medical and Health Sciences, Department of Pharmacology and the National Research Centre for Growth and Development, The University of Auckland, Auckland, New Zealand
| | - Boris Rogelj
- Department of Clinical Neuroscience and
- Department of Biotechnology, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
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Bentmann E, Haass C, Dormann D. Stress granules in neurodegeneration - lessons learnt from TAR DNA binding protein of 43 kDa and fused in sarcoma. FEBS J 2013; 280:4348-70. [DOI: 10.1111/febs.12287] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/28/2013] [Accepted: 04/08/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Eva Bentmann
- Adolf Butenandt Institute; Department of Biochemistry; Ludwig Maximilians University; Munich Germany
| | - Christian Haass
- Adolf Butenandt Institute; Department of Biochemistry; Ludwig Maximilians University; Munich Germany
- German Center for Neurodegenerative Diseases (DZNE); Munich Germany
- Munich Cluster for Systems Neurology (SyNergy); Munich Germany
| | - Dorothee Dormann
- Adolf Butenandt Institute; Department of Biochemistry; Ludwig Maximilians University; Munich Germany
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Miyazaki K, Yamashita T, Morimoto N, Sato K, Mimoto T, Kurata T, Ikeda Y, Abe K. Early and selective reduction of NOP56 (Asidan) and RNA processing proteins in the motor neuron of ALS model mice. Neurol Res 2013; 35:744-54. [PMID: 23582672 DOI: 10.1179/1743132813y.0000000196] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE There is increasing evidence to support that altered RNA processing is implicated in the pathogenesis of motor neuron degeneration of amyotrophic lateral sclerosis (ALS). We evaluate the expression of three RNA processing-related proteins in ALS model mice in this study. METHODS We analyzed expression and distribution patterns of three RNA processing-related proteins, nucleolar protein (NOP) 56 (identified as causative gene for spinocerebellar ataxia (SCA) 36, nicknamed Asidan), TDP-43, and fused in sarcoma/translocated in liposarcoma (FUS) in lumbar and cervical cords, hypoglossal nucleus, cerebral motor cortex, and cerebellum of transgenic (Tg) SOD1 G93A ALS model mice throughout the course of motor neuron degeneration. RESULTS Compared to age-matched wild type (WT) mice, Tg mice showed progressive reduction of NOP56 levels in the large motor neurons of lumbar and cervical cords from the early-symptomatic stage (14 weeks of age) to the end stage of the disease (18 weeks). TDP-43 and FUS protein levels showed a later decrease in the nucleus of large motor neuron at 18 weeks (end stage of the disease). These changes were not observed in the primary motor cortex of the cerebrum as well as molecular and granular layers and Purkinje cells in the cerebellum. DISCUSSION The present study suggests a progressive loss of these three nuclear proteins and subsequent RNA processing problems including a novel gene relating to ALS (NOP56) under the motor neuron degeneration.
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Affiliation(s)
- Kazunori Miyazaki
- Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science, Shikata-cho, Okayama, Japan
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van Blitterswijk M, Wang ET, Friedman BA, Keagle PJ, Lowe P, Leclerc AL, van den Berg LH, Housman DE, Veldink JH, Landers JE. Characterization of FUS mutations in amyotrophic lateral sclerosis using RNA-Seq. PLoS One 2013; 8:e60788. [PMID: 23577159 PMCID: PMC3620060 DOI: 10.1371/journal.pone.0060788] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 03/02/2013] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease resulting in severe muscle weakness and eventual death by respiratory failure. Although little is known about its pathogenesis, mutations in fused in sarcoma/translated in liposarcoma (FUS) are causative for familial ALS. FUS is a multifunctional protein that is involved in many aspects of RNA processing. To elucidate the role of FUS in ALS, we overexpressed wild-type and two mutant forms of FUS in HEK-293T cells, as well as knocked-down FUS expression. This was followed by RNA-Seq to identify genes which displayed differential expression or altered splicing patterns. Pathway analysis revealed that overexpression of wild-type FUS regulates ribosomal genes, whereas knock-down of FUS additionally affects expression of spliceosome related genes. Furthermore, cells expressing mutant FUS displayed global transcription patterns more similar to cells overexpressing wild-type FUS than to the knock-down condition. This observation suggests that FUS mutants do not contribute to the pathogenesis of ALS through a loss-of-function. Finally, our results demonstrate that the R521G and R522G mutations display differences in their influence on transcription and splicing. Taken together, these results provide additional insights into the function of FUS and how mutations contribute to the development of ALS.
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Affiliation(s)
- Marka van Blitterswijk
- Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, United States of America
| | - Eric T. Wang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, United States of America
| | - Brad A. Friedman
- Department of Molecular and Cell Biology, Harvard University, Cambridge, Massachusetts, United States of America
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Pamela J. Keagle
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, United States of America
| | - Patrick Lowe
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, United States of America
| | - Ashley Lyn Leclerc
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, United States of America
| | - Leonard H. van den Berg
- Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
| | - David E. Housman
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Jan H. Veldink
- Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
| | - John E. Landers
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, United States of America
- * E-mail:
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Vaccaro A, Patten SA, Aggad D, Julien C, Maios C, Kabashi E, Drapeau P, Parker JA. Pharmacological reduction of ER stress protects against TDP-43 neuronal toxicity in vivo. Neurobiol Dis 2013; 55:64-75. [PMID: 23567652 DOI: 10.1016/j.nbd.2013.03.015] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 02/20/2013] [Accepted: 03/26/2013] [Indexed: 01/09/2023] Open
Abstract
C. elegans and D. rerio expressing mutant TAR DNA Binding Protein 43 (TDP-43) are powerful in vivo animal models for the genetics and pharmacology of amyotrophic lateral sclerosis (ALS). Using these small-animal models of ALS, we previously identified methylene blue (MB) as a potent suppressor of TDP-43 toxicity. Consequently here we investigated how MB might exert its neuroprotective properties and found that it acts through reduction of the endoplasmic reticulum (ER) stress response. We tested other compounds known to be active in the ER unfolded protein response in worms and zebrafish expressing mutant human TDP-43 (mTDP-43). We identified three compounds: salubrinal, guanabenz and a new structurally related compound phenazine, which also reduced paralysis, neurodegeneration and oxidative stress in our mTDP-43 models. Using C. elegans genetics, we showed that all four compounds act as potent suppressors of mTDP-43 toxicity through reduction of the ER stress response. Interestingly, these compounds operate through different branches of the ER unfolded protein pathway to achieve a common neuroprotective action. Our results indicate that protein-folding homeostasis in the ER is an important target for therapeutic development in ALS and other TDP-43-related neurodegenerative diseases.
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Verma A, Tandan R. RNA quality control and protein aggregates in amyotrophic lateral sclerosis: a review. Muscle Nerve 2013; 47:330-8. [PMID: 23381726 DOI: 10.1002/mus.23673] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2012] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease in adults. The biologic basis of ALS remains unknown. However, ALS research has taken a dramatic turn over the past 4 years. Ground breaking discoveries of mutations of genes that encode RNA processing proteins, and demonstration that abnormal aggregates of these and other proteins precede motor neuron loss in familial and sporadic ALS, have initiated a paradigm shift in understanding the pathogenic mechanisms of ALS. Curiously, some of these RNA binding proteins have prion-like domains, with a propensity to self-aggregation. The emerging hypothesis that a focal cascade of toxic protein aggregates, and their consequent non-cell-autonomous spread to neighborhood groups of neurons, fits the classical temporo-spatial progression of ALS. This article reviews the current research efforts toward understanding the role of RNA-processing regulation and protein aggregates in ALS.
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Affiliation(s)
- Ashok Verma
- Department of Neurology, University of Miami Miller School of Medicine, Clinical Research Building, 1120 NW 14 Street, Suite 1317, Miami, Florida 33136, USA.
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31
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Bibonne A, Néant I, Batut J, Leclerc C, Moreau M, Gilbert T. Three calcium-sensitive genes, fus, brd3 and wdr5, are highly expressed in neural and renal territories during amphibian development. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1665-71. [PMID: 23287019 DOI: 10.1016/j.bbamcr.2012.12.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 01/08/2023]
Abstract
Numerous Ca(2+) signaling events have been associated with early development of vertebrate embryo, from fertilization to organogenesis. In Xenopus laevis, Ca(2+) signals are key regulators in the earliest steps of the nervous system development. If neural determination is one of the best-characterized examples of the role of Ca(2+) during embryogenesis, increasing literature supports a determining role of organogenesis and differentiation. In blastula the cells of the presumptive ectoderm (animal caps) are pluripotent and can be induced toward neural fate with an intracellular increase of free Ca(2+) triggered by caffeine. To identify genes that are transcribed early upon Ca(2+) stimuli and involved in neural determination, we have constructed a subtractive cDNA library between neuralized and non-neuralized animal caps. Here we present the expression pattern of three new Ca(2+)-sensitive genes: fus (fused in sarcoma), brd3 (bromodomain containing 3) and wdr5 (WD repeat domain 5) as they all represent potential regulators of the transcriptional machinery. Using in situ hybridization we illustrated the spatial expression pattern of fus, brd3 and wdr5 during early developmental stages of Xenopus embryos. Strikingly, their domains of expression are not restricted to neural territories. They all share a specific expression throughout renal organogenesis which has been found to rely also on Ca(2+) signaling. This therefore highlights the key function of Ca(2+) target genes in specific territories during early development. We propose that Ca(2+) signaling through modulation of fus, brd3 and wdr5 expressions can control the transcription machinery to achieve proper embryogenesis. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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Affiliation(s)
- A Bibonne
- Université Toulouse 3, Centre de Biologie du Développement, Toulouse, France
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32
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Ribonuclease 4 protects neuron degeneration by promoting angiogenesis, neurogenesis, and neuronal survival under stress. Angiogenesis 2012; 16:387-404. [PMID: 23143660 DOI: 10.1007/s10456-012-9322-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 11/01/2012] [Indexed: 10/27/2022]
Abstract
Altered RNA processing is an underlying mechanism of amyotrophic lateral sclerosis (ALS). Missense mutations in a number of genes involved in RNA function and metabolisms are associated with ALS. Among these genes is angiogenin (ANG), the fifth member of the vertebrate-specific, secreted ribonuclease superfamily. ANG is an angiogenic ribonuclease, and both its angiogenic and ribonucleolytic activities are important for motor neuron health. Ribonuclease 4 (RNASE4), the fourth member of this superfamily, shares the same promoters with ANG and is co-expressed with ANG. However, the biological role of RNASE4 is unknown. To determine whether RNASE4 is involved in ALS pathogenesis, we sequenced the coding region of RNASE4 in ALS and control subjects and characterized the angiogenic, neurogenic, and neuroprotective activities of RNASE4 protein. We identified an allelic association of SNP rs3748338 with ALS and demonstrated that RNASE4 protein is able to induce angiogenesis in in vitro, ex vivo, and in vivo assays. RNASE4 also induces neural differentiation of P19 mouse embryonal carcinoma cells and mouse embryonic stem cells. Moreover, RNASE4 not only stimulates the formation of neurofilaments from mouse embryonic cortical neurons, but also protects hypothermia-induced degeneration. Importantly, systemic treatment with RNASE4 protein slowed weight loss and enhanced neuromuscular function of SOD1 (G93A) mice.
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Verma A. Altered RNA metabolism and amyotrophic lateral sclerosis. Ann Indian Acad Neurol 2012; 14:239-44. [PMID: 22346009 PMCID: PMC3271459 DOI: 10.4103/0972-2327.91933] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Revised: 10/14/2011] [Accepted: 11/15/2011] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease in adults. Typically, patients with ALS develop progressive weakness resulting, eventually, in respiratory muscle paralysis and death in 3-5 years after the onset of the disease. No definite therapy currently exists for ALS. The biologic basis of the disease is unknown. However, ALS research has taken a dramatic turn over the last 3 years. Landmark discoveries of mutations in the transactive response DNA-binding protein (TDP-43) and fused in sarcoma/translocated in liposarcoma (FUS/TLS) as causative of ALS and demonstration that abnormal aggregation of these proteins is the proximate cause of motor neuron loss in familial and sporadic ALS have initiated a paradigm shift in understanding the pathogenic mechanism of this disease. TDP-43 and FUS/TLS are DNA/RNA-binding proteins with striking structural and functional similarities. This article reviews the current direction of research efforts toward understanding the role of RNA (ribonucleic acid) processing regulation in ALS and possible therapeutic pathways in this fatal disease.
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Affiliation(s)
- Ashok Verma
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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Henriques A, Gonzalez De Aguilar JL. Can transcriptomics cut the gordian knot of amyotrophic lateral sclerosis? Curr Genomics 2012; 12:506-15. [PMID: 22547957 PMCID: PMC3219845 DOI: 10.2174/138920211797904043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Revised: 07/27/2011] [Accepted: 09/15/2011] [Indexed: 12/31/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is an adult-onset degenerative disease characterized by the loss of upper and lower motor neurons, progressive muscle atrophy, paralysis and death, which occurs within 2-5 years of diagnosis. Most cases appear sporadically but some are familial, usually inherited in an autosomal dominant pattern. It is postulated that the disease results from the combination of multiple pathogenic mechanisms, which affect not only motor neurons but also non-neuronal neighboring cells. Together with the understanding of this intriguing cell biology, important challenges in the field concern the design of effective curative treatments and the discovery of molecular biomarkers for early diagnosis and accurate monitoring of disease progression. During the last decade, transcriptomics has represented a promising approach to address these questions. In this review, we revisit the major findings of the numerous studies that analyzed global gene expression in tissues and cells from biopsy or post-mortem specimens of ALS patients and related animal models. These studies corroborated the implication of previously described disease pathways, and investigated the role of new genes in the pathological process. In addition, they also identified gene expression changes that could be used as candidate biomarkers for the diagnosis and follow-up of ALS. The limitations of these transcriptomics approaches will be also discussed.
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Affiliation(s)
- Alexandre Henriques
- INSERM, U692, Laboratoire de Signalisations Moléculaires et Neurodégénérescence, Strasbourg, France
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35
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Position-dependent FUS-RNA interactions regulate alternative splicing events and transcriptions. Sci Rep 2012; 2:529. [PMID: 22829983 PMCID: PMC3402842 DOI: 10.1038/srep00529] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 07/09/2012] [Indexed: 12/12/2022] Open
Abstract
FUS is an RNA-binding protein that regulates transcription, alternative splicing, and mRNA transport. Aberrations of FUS are causally associated with familial and sporadic ALS/FTLD. We analyzed FUS-mediated transcriptions and alternative splicing events in mouse primary cortical neurons using exon arrays. We also characterized FUS-binding RNA sites in the mouse cerebrum with HITS-CLIP. We found that FUS-binding sites tend to form stable secondary structures. Analysis of position-dependence of FUS-binding sites disclosed scattered binding of FUS to and around the alternatively spliced exons including those associated with neurodegeneration such as Mapt, Camk2a, and Fmr1. We also found that FUS is often bound to the antisense RNA strand at the promoter regions. Global analysis of these FUS-tags and the expression profiles disclosed that binding of FUS to the promoter antisense strand downregulates transcriptions of the coding strand. Our analysis revealed that FUS regulates alternative splicing events and transcriptions in a position-dependent manner.
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Satoh M, Ceribelli A, Chan EKL. Common pathways of autoimmune inflammatory myopathies and genetic neuromuscular disorders. Clin Rev Allergy Immunol 2012; 42:16-25. [PMID: 22083460 DOI: 10.1007/s12016-011-8286-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
It has been shown that many hereditary motor neuron diseases are caused by mutation of RNA processing enzymes. Survival of motor neuron 1 (SMN1) is well-known as a causative gene for spinal muscular atrophy (SMA) and mutations of glycyl- and tyrosyl-tRNA synthetases are identified as a cause of distal SMA and Charcot-Marie-Tooth disease. Why and how the dysfunction of these ubiquitously expressed genes involved in RNA processing can cause a specific neurological disorder is not well understood. Interestingly, SMN complex has been identified recently as a new target of autoantibodies in polymyositis (PM). Autoantibodies in systemic rheumatic diseases are clinically useful biomarkers associated with a particular diagnosis, subset of a disease, or certain clinical characteristics. Many autoantibodies produced in patients with polymyositis/dermatomyositis (PM/DM) target RNA-protein complexes such as aminoacyl tRNA synthetases. It is interesting to note these same RNA-protein complexes recognized by autoantibodies in PM/DM are also responsible for genetic neuromuscular disease. Certain RNA-protein complexes are also targets of autoantibodies in paraneoplastic neurological disorders. Thus, there are several interesting associations between RNA-processing enzymes and neuromuscular disorders. Although pathogenetic roles of autoantibodies to intracellular antigens are generally considered unlikely, understanding the mechanisms of antigen selection in a particular disease and specific neurological symptoms caused by disruption of ubiquitous RNA-processing enzyme may help identify a common path in genetic neuromuscular disorders and autoimmunity in inflammatory myopathies.
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Affiliation(s)
- Minoru Satoh
- Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Florida, Gainesville, FL 32610-0221, USA.
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Abstract
RNA helicases unwind their RNA substrates in an ATP-dependent reaction, and are central to all cellular processes involving RNA. They have important roles in viral life cycles, where RNA helicases are either virus-encoded or recruited from the host. Vertebrate RNA helicases sense viral infections, and trigger the innate antiviral immune response. RNA helicases have been implicated in protozoic, bacterial and fungal infections. They are also linked to neurological disorders, cancer, and aging processes. Genome-wide studies continue to identify helicase genes that change their expression patterns after infection or disease outbreak, but the mechanism of RNA helicase action has been defined for only a few diseases. RNA helicases are prognostic and diagnostic markers and suitable drug targets, predominantly for antiviral and anti-cancer therapies. This review summarizes the current knowledge on RNA helicases in infection and disease, and their growing potential as drug targets.
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Affiliation(s)
- Lenz Steimer
- University of Muenster, Institute for Physical Chemistry, Muenster, Germany
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Colombrita C, Onesto E, Megiorni F, Pizzuti A, Baralle FE, Buratti E, Silani V, Ratti A. TDP-43 and FUS RNA-binding proteins bind distinct sets of cytoplasmic messenger RNAs and differently regulate their post-transcriptional fate in motoneuron-like cells. J Biol Chem 2012; 287:15635-47. [PMID: 22427648 DOI: 10.1074/jbc.m111.333450] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The RNA-binding proteins TDP-43 and FUS form abnormal cytoplasmic aggregates in affected tissues of patients with amyotrophic lateral sclerosis and frontotemporal lobar dementia. TDP-43 and FUS localize mainly in the nucleus where they regulate pre-mRNA splicing, but they are also involved in mRNA transport, stability, and translation. To better investigate their cytoplasmic activities, we applied an RNA immunoprecipitation and chip analysis to define the mRNAs associated to TDP-43 and FUS in the cytoplasmic ribonucleoprotein complexes from motoneuronal NSC-34 cells. We found that they bind different sets of mRNAs although converging on common cellular pathways. Bioinformatics analyses identified the (UG)(n) consensus motif in 80% of 3'-UTR sequences of TDP-43 targets, whereas for FUS the binding motif was less evident. By in vitro assays we validated binding to selected target 3'-UTRs, including Vegfa and Grn for TDP-43, and Vps54, Nvl, and Taf15 for FUS. We showed that TDP-43 has a destabilizing activity on Vegfa and Grn mRNAs and may ultimately affect progranulin protein content, whereas FUS does not affect mRNA stability/translation of its targets. We also demonstrated that three different point mutations in TDP-43 did not change the binding affinity for Vegfa and Grn mRNAs or their protein level. Our data indicate that TDP-43 and FUS recognize distinct sets of mRNAs and differently regulate their fate in the cytoplasm of motoneuron-like cells, therefore suggesting complementary roles in neuronal RNA metabolism and neurodegeneration.
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Affiliation(s)
- Claudia Colombrita
- Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan 20149, Italy
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Nuclear localization of human SOD1 and mutant SOD1-specific disruption of survival motor neuron protein complex in transgenic amyotrophic lateral sclerosis mice. J Neuropathol Exp Neurol 2012; 71:162-77. [PMID: 22249462 DOI: 10.1097/nen.0b013e318244b635] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disease that causes degeneration of motor neurons and paralysis. Approximately 20% of familial ALS cases have been linked to mutations in the copper/zinc superoxide dismutase (SOD1) gene, but it is unclear how mutations in the protein result in motor neuron degeneration. Transgenic (tg) mice expressing mutated forms of human SOD1 (hSOD1) develop clinical and pathological features similar to those of ALS. We used tg mice expressing hSOD1-G93A, hSOD1-G37R, and hSOD1-wild-type to investigate a new subcellular pathology involving mutant hSOD1 protein prominently localizing to the nuclear compartment and disruption of the architecture of nuclear gems. We developed methods for extracting relatively pure cell nucleus fractions from mouse CNS tissues and demonstrate a low nuclear presence of endogenous SOD1 in mouse brain and spinal cord, but prominent nuclear accumulation of hSOD1-G93A, -G37R, and -wild-type in tg mice. The hSOD1 concentrated in the nuclei of spinal cord cells, particularly motor neurons, at a young age. The survival motor neuron protein (SMN) complex is disrupted in motor neuron nuclei before disease onset in hSOD1-G93A and -G37R mice; age-matched hSOD1-wild-type mice did not show SMN disruption despite a nuclear presence. Our data suggest new mechanisms involving hSOD1 accumulation in the cell nucleus and mutant hSOD1-specific perturbations in SMN localization with disruption of the nuclear SMN complex in ALS mice and suggest an overlap of pathogenic mechanisms with spinal muscular atrophy.
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Pratt AJ, Getzoff ED, Perry JJP. Amyotrophic lateral sclerosis: update and new developments. Degener Neurol Neuromuscul Dis 2012; 2012:1-14. [PMID: 23019386 PMCID: PMC3457793 DOI: 10.2147/dnnd.s19803] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common form of motor neuron disease. It is typically characterized by adult-onset degeneration of the upper and lower motor neurons, and is usually fatal within a few years of onset. A subset of ALS patients has an inherited form of the disease, and a few of the known mutant genes identified in familial cases have also been found in sporadic forms of ALS. Precisely how the diverse ALS-linked gene products dictate the course of the disease, resulting in compromised voluntary muscular ability, is not entirely known. This review addresses the major advances that are being made in our understanding of the molecular mechanisms giving rise to the disease, which may eventually translate into new treatment options.
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Affiliation(s)
- Ashley J Pratt
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA,
| | - Elizabeth D Getzoff
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA,
| | - J Jefferson P Perry
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA,
- The School of Biotechnology, Amrita University, Kollam, Kerala 690525, India,
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41
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Budini M, Buratti E, Stuani C, Guarnaccia C, Romano V, De Conti L, Baralle FE. Cellular model of TAR DNA-binding protein 43 (TDP-43) aggregation based on its C-terminal Gln/Asn-rich region. J Biol Chem 2012; 287:7512-25. [PMID: 22235134 DOI: 10.1074/jbc.m111.288720] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
TDP-43 is one of the major components of the neuronal and glial inclusions observed in several neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal lobar degeneration. These characteristic aggregates are a "landmark" of the disease, but their role in the pathogenesis is still obscure. In previous works, we have shown that the C-terminal Gln/Asn-rich region (residues 321-366) of TDP-43 is involved in the interaction of this protein with other members of the heterogeneous nuclear ribonucleoprotein protein family. Furthermore, we have shown that the interaction through this region is important for TDP-43 splicing inhibition of cystic fibrosis transmembrane regulator exon 9, and there were indications that it was involved in the aggregation process. Our experiments show that in cell lines and primary rat neuronal cultures, the introduction of tandem repeats carrying the 331-369-residue Gln/Asn region from TDP-43 can trigger the formation of phosphorylated and ubiquitinated aggregates that recapitulate many but not all the characteristics observed in patients. These results establish a much needed cell-based TDP-43 aggregation model useful to investigate the mechanisms involved in the formation of inclusions and the gain- and loss-of-function consequences of TDP-43 aggregation within cells. In addition, it will be a powerful tool to test novel therapeutic strategies/effectors aimed at preventing/reducing this phenomenon.
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Affiliation(s)
- Mauricio Budini
- International Centre for Genetic Engineering and Biotechnology, 34012 Trieste, Italy
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42
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Cerebrovascular disorders: molecular insights and therapeutic opportunities. Nat Neurosci 2011; 14:1390-7. [DOI: 10.1038/nn.2947] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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43
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Bosco DA, LaVoie MJ, Petsko GA, Ringe D. Proteostasis and movement disorders: Parkinson's disease and amyotrophic lateral sclerosis. Cold Spring Harb Perspect Biol 2011; 3:a007500. [PMID: 21844169 DOI: 10.1101/cshperspect.a007500] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Parkinson's disease (PD) is a movement disorder that afflicts over one million in the U.S.; amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is less prevalent but also has a high incidence. The two disorders sometimes present together, making a comparative study of interest. Both ALS and PD are neurodegenerative diseases, and are characterized by the presence of intraneuronal inclusions; however, different classes of neurons are affected and the primary protein in the inclusions differs between the diseases, and in some cases is different in distinct forms of the same disease. These observations might suggest that the more general approach of proteostasis pathway alteration would be a powerful one in treating these disorders. Examining results from human genetics and studies in model organisms, as well as from biochemical and biophysical characterization of the proteins involved in both diseases, we find that most instances of PD can be considered as arising from the misfolding, and self-association to a toxic species, of the small neuronal protein α-synuclein, and that proteostasis strategies are likely to be of value for this disorder. For ALS, the situation is much more complex and less clear-cut; the available data are most consistent with a view that ALS may actually be a family of disorders, presenting similarly but arising from distinct and nonoverlapping causes, including mislocalization of some properly folded proteins and derangement of RNA quality control pathways. Applying proteostasis approaches to this disease may require rethinking or broadening the concept of what proteostasis means.
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Affiliation(s)
- Daryl A Bosco
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts 01655, USA
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44
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Wang JW, Brent JR, Tomlinson A, Shneider NA, McCabe BD. The ALS-associated proteins FUS and TDP-43 function together to affect Drosophila locomotion and life span. J Clin Invest 2011; 121:4118-26. [PMID: 21881207 DOI: 10.1172/jci57883] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 07/27/2011] [Indexed: 11/17/2022] Open
Abstract
The fatal adult motor neuron disease amyotrophic lateral sclerosis (ALS) shares some clinical and pathological overlap with frontotemporal dementia (FTD), an early-onset neurodegenerative disorder. The RNA/DNA-binding proteins fused in sarcoma (FUS; also known as TLS) and TAR DNA binding protein-43 (TDP-43) have recently been shown to be genetically and pathologically associated with familial forms of ALS and FTD. It is currently unknown whether perturbation of these proteins results in disease through mechanisms that are independent of normal protein function or via the pathophysiological disruption of molecular processes in which they are both critical. Here, we report that Drosophila mutants in which the homolog of FUS is disrupted exhibit decreased adult viability, diminished locomotor speed, and reduced life span compared with controls. These phenotypes were fully rescued by wild-type human FUS, but not ALS-associated mutant FUS proteins. A mutant of the Drosophila homolog of TDP-43 had similar, but more severe, deficits. Through cross-rescue analysis, we demonstrated that FUS acted together with and downstream of TDP-43 in a common genetic pathway in neurons. Furthermore, we found that these proteins associated with each other in an RNA-dependent complex. Our results establish that FUS and TDP-43 function together in vivo and suggest that molecular pathways requiring the combined activities of both of these proteins may be disrupted in ALS and FTD.
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Affiliation(s)
- Ji-Wu Wang
- Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, New York 10032, USA
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45
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Gallo A, Locatelli F. ADARs: allies or enemies? The importance of A-to-I RNA editing in human disease: from cancer to HIV-1. Biol Rev Camb Philos Soc 2011; 87:95-110. [PMID: 21682836 DOI: 10.1111/j.1469-185x.2011.00186.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Adenosine deaminases acting on RNA (ADARs) are enzymes that convert adenosine (A) to inosine (I) in nuclear-encoded RNAs and viral RNAs. The activity of ADARs has been demonstrated to be essential in mammals and serves to fine-tune different proteins and modulate many molecular pathways. Recent findings have shown that ADAR activity is altered in many pathological tissues. Moreover, it has been shown that modulation of RNA editing is important for cell proliferation and migration, and has a protective effect on ischaemic insults. This review summarises available recent knowledge on A-to-I RNA editing and ADAR enzymes, with particular attention given to the emerging role played by these enzymes in cancer, some infectious diseases and immune-mediated disorders.
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Affiliation(s)
- Angela Gallo
- RNA Editing Laboratory, Oncohaematology Department, IRCCS, Ospedale Pediatrico "Bambino Gesù", Rome, Italy.
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46
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Budini M, Buratti E. TDP-43 autoregulation: implications for disease. J Mol Neurosci 2011; 45:473-9. [PMID: 21681666 DOI: 10.1007/s12031-011-9573-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 06/06/2011] [Indexed: 12/13/2022]
Abstract
TDP-43 is a nuclear protein that has been shown to play a central role in RNA metabolism. In recent years, this protein has become very important in the study of neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal lobar degeneration (FTLD). These diseases share, as common feature, the presence of abnormally aggregated, posttranslationally modified, and mislocalized TDP-43 in the cell cytoplasm of both neurons and glial cells. A major question in TDP-43 research is represented by the investigation of the mechanism(s) that trigger this process and its potential consequences. Regarding the first issue, it is likely that relative protein expression levels might play an important role as has been demonstrated for many protein aggregation processes. In fact, the eventual misregulation of TDP-43 expression leading to enhanced protein production might well correlate with enhanced aggregation, and thus results in increasingly harmful gain- or loss-of-function effects on cellular metabolism. For this reason, it is important to determine the mechanisms that act to regulate TDP-43 levels within the cell. In normal conditions, it is now clear that TDP-43 can modulate its own protein levels through a negative feedback loop triggered by binding to its own RNA in the 3'UTR region leading to mRNA degradation. This work discusses how an eventual disruption of this mechanism might affect TDP-43 pathology, focusing in particular on its association with stress granules and intrinsic aggregation properties.
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Affiliation(s)
- Mauricio Budini
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012, Trieste, Italy
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47
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Flomen R, Makoff A. Increased RNA editing in EAAT2 pre-mRNA from amyotrophic lateral sclerosis patients: involvement of a cryptic polyadenylation site. Neurosci Lett 2011; 497:139-43. [PMID: 21569822 DOI: 10.1016/j.neulet.2011.04.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/08/2011] [Accepted: 04/19/2011] [Indexed: 01/08/2023]
Abstract
The astroglial EAAT2 glutamate transporter is essential for clearing glutamate in the central nervous system and protecting against excitotoxicity. It is implicated in amyotrophic lateral sclerosis (ALS, the most common type of motor neurone disease) where less EAAT2 is found, possibly involving aberrant intron 7 retention transcripts. We report adenine/inosine RNA editing at a novel site in intron 7 of EAAT2 pre-mRNA that appears to activate a cryptic alternative polyadenylation site, generating intron 7 retention transcripts. This polyadenylation site includes two overlapping polyadenylation signals opposite the editing site in a strong stem-loop, which is highly conserved in primates. In pre-mRNA, we observed variable editing levels at this site, which were significantly higher in spinal cord (p=0.001) and motor cortex (p=0.005) from ALS patients, but not in cerebellum, demonstrating specificity for clinically relevant regions. By contrast, incomplete mRNA molecules polyadenylated in intron 7 are always completely edited. Cell culture experiments confirm this strong correlation between editing and polyadenylation in intron 7, strongly suggesting activation of the alternative polyadenylation site by editing. Prediction of inosine base-pairing from published data suggests that RNA editing releases the polyadenylation signals from the stem-loop, providing a plausible mechanism. To the best of our knowledge, this is the first report of RNA editing activating an alternative polyadenylation signal.
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Affiliation(s)
- Rachel Flomen
- King's College London, Department of Clinical Neuroscience, Institute of Psychiatry, PO51, De Crespigny Park Denmark Hill, London SE58AF, United Kingdom
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48
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Abstract
TDP-43 mislocalization and aggregation are implicated in the pathogenesis of ALS and FTLD-U. Valosin containing protein (VCP) mutations also lead to TDP-43 deposition, resulting in Inclusion Body Myopathy, Paget disease, and Frontotemporal Dementia (IBMPFD). In this issue of Neuron, Johnson et al. used whole-exome capture to identify VCP mutations in familial ALS. This extends the VCP phenotype to include motor neuron degeneration and provides another molecular tool to explore neurodegeneration disease mechanisms underlying the TDP-43 proteinopathies.
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Affiliation(s)
- Christopher E Shaw
- King's College London, MRC Centre for Neurodegeneration Research, Department of Clinical Neuroscience, Institute of Psychiatry, London SE5 8AF, UK.
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49
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Uversky VN. Targeting intrinsically disordered proteins in neurodegenerative and protein dysfunction diseases: another illustration of the D(2) concept. Expert Rev Proteomics 2010; 7:543-64. [PMID: 20653509 DOI: 10.1586/epr.10.36] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Many biologically active proteins, which are usually called intrinsically disordered or natively unfolded proteins, lack stable tertiary and/or secondary structure under physiological conditions in vitro. Their functions complement the functional repertoire of ordered proteins, with intrinsically disordered proteins (IDPs) often being involved in regulation, signaling and control. Their amino acid sequences and compositions are very different from those of ordered proteins, making reliable identification of IDPs possible at the proteome level. IDPs are highly abundant in various human diseases, including neurodegeneration and other protein dysfunction maladies and, therefore, represent attractive novel drug targets. Some of the aspects of IDPs, as well as their roles in neurodegeneration and protein dysfunction diseases, are discussed in this article, together with the peculiarities of IDPs as potential drug targets.
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Affiliation(s)
- Vladimir N Uversky
- Institute for Intrinsically Disordered Protein Research, Center for Computational Biology and Bioinformatics, and Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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50
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Bosco DA, Lemay N, Ko HK, Zhou H, Burke C, Kwiatkowski TJ, Sapp P, McKenna-Yasek D, Brown RH, Hayward LJ. Mutant FUS proteins that cause amyotrophic lateral sclerosis incorporate into stress granules. Hum Mol Genet 2010; 19:4160-75. [PMID: 20699327 DOI: 10.1093/hmg/ddq335] [Citation(s) in RCA: 390] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutations in the RNA-binding protein FUS (fused in sarcoma) are linked to amyotrophic lateral sclerosis (ALS), but the mechanism by which these mutants cause motor neuron degeneration is not known. We report a novel ALS truncation mutant (R495X) that leads to a relatively severe ALS clinical phenotype compared with FUS missense mutations. Expression of R495X FUS, which abrogates a putative nuclear localization signal at the C-terminus of FUS, in HEK-293 cells and in the zebrafish spinal cord caused a striking cytoplasmic accumulation of the protein to a greater extent than that observed for recessive (H517Q) and dominant (R521G) missense mutants. Furthermore, in response to oxidative stress or heat shock conditions in cultures and in vivo, the ALS-linked FUS mutants, but not wild-type FUS, assembled into perinuclear stress granules in proportion to their cytoplasmic expression levels. These findings demonstrate a potential link between FUS mutations and cellular pathways involved in stress responses that may be relevant to altered motor neuron homeostasis in ALS.
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Affiliation(s)
- Daryl A Bosco
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
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