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Matera AG, Steiner RE, Mills CA, Herring LE, Garcia EL. Chaperoning the chaperones: Proteomic analysis of the SMN complex reveals conserved and etiologic connections to the proteostasis network. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.15.594402. [PMID: 38903116 PMCID: PMC11188114 DOI: 10.1101/2024.05.15.594402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Molecular chaperones and co-chaperones are highly conserved cellular components that perform variety of duties related to the proper three-dimensional folding of the proteome. The web of factors that carries out this essential task is called the proteostasis network (PN). Ribonucleoproteins (RNPs) represent an underexplored area in terms of the connections they make with the PN. The Survival Motor Neuron (SMN) complex is an RNP assembly chaperone and serves as a paradigm for studying how specific small nuclear (sn)RNAs are identified and paired with their client substrate proteins. SMN protein is the eponymous component of a large complex required for the biogenesis of uridine-rich small nuclear ribonucleoproteins (U-snRNPs) and localizes to distinct membraneless organelles in both the nucleus and cytoplasm of animal cells. SMN forms the oligomeric core of this complex, and missense mutations in its YG box self-interaction domain are known to cause Spinal Muscular Atrophy (SMA). The basic framework for understanding how snRNAs are assembled into U-snRNPs is known, the pathways and mechanisms used by cells to regulate their biogenesis are poorly understood. Given the importance of these processes to normal development as well as neurodegenerative disease, we set out to identify and characterize novel SMN binding partners. Here, we carried out affinity purification mass spectrometry (AP-MS) of SMN using stable fly lines exclusively expressing either wildtype or SMA-causing missense alleles. Bioinformatic analyses of the pulldown data, along with comparisons to proximity labeling studies carried out in human cells, revealed conserved connections to at least two other major chaperone systems including heat shock folding chaperones (HSPs) and histone/nucleosome assembly chaperones. Notably, we found that heat shock cognate protein Hsc70-4 and other HspA family members preferentially interacted with SMA-causing alleles of SMN. Hsc70-4 is particularly interesting because its mRNA is aberrantly sequestered by a mutant form of TDP-43 in mouse and Drosophila ALS (Amyotrophic Lateral Sclerosis) disease models. Most important, a missense allele of Hsc70-4 (HspA8 in mammals) was recently identified as a bypass suppressor of the SMA phenotype in mice. Collectively, these findings suggest that chaperone-related dysfunction lies at the etiological root of both ALS and SMA.
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Affiliation(s)
- A. Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill NC, USA
- Departments of Biology and Genetics, University of North Carolina at Chapel Hill
- RNA Discovery and Lineberger Comprehensive Cancer Centers, University of North Carolina at Chapel Hill
| | - Rebecca E. Steiner
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill NC, USA
| | - C. Alison Mills
- Department of Pharmacology, University of North Carolina at Chapel Hill
| | - Laura E. Herring
- Department of Pharmacology, University of North Carolina at Chapel Hill
| | - Eric L. Garcia
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill NC, USA
- Department of Biology, University of Kentucky, Lexington KY, USA
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2
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Garcia EL, Steiner RE, Raimer AC, Herring LE, Matera AG, Spring AM. Dysregulation of innate immune signaling in animal models of spinal muscular atrophy. BMC Biol 2024; 22:94. [PMID: 38664795 PMCID: PMC11044505 DOI: 10.1186/s12915-024-01888-z] [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: 10/28/2023] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND Spinal muscular atrophy (SMA) is a devastating neuromuscular disease caused by hypomorphic loss of function in the survival motor neuron (SMN) protein. SMA presents across a broad spectrum of disease severity. Unfortunately, genetic models of intermediate SMA have been difficult to generate in vertebrates and are thus unable to address key aspects of disease etiology. To address these issues, we developed a Drosophila model system that recapitulates the full range of SMA severity, allowing studies of pre-onset biology as well as late-stage disease processes. RESULTS Here, we carried out transcriptomic and proteomic profiling of mild and intermediate Drosophila models of SMA to elucidate molecules and pathways that contribute to the disease. Using this approach, we elaborated a role for the SMN complex in the regulation of innate immune signaling. We find that mutation or tissue-specific depletion of SMN induces hyperactivation of the immune deficiency (IMD) and Toll pathways, leading to overexpression of antimicrobial peptides (AMPs) and ectopic formation of melanotic masses in the absence of an external challenge. Furthermore, the knockdown of downstream targets of these signaling pathways reduced melanotic mass formation caused by SMN loss. Importantly, we identify SMN as a negative regulator of a ubiquitylation complex that includes Traf6, Bendless, and Diap2 and plays a pivotal role in several signaling networks. CONCLUSIONS In alignment with recent research on other neurodegenerative diseases, these findings suggest that hyperactivation of innate immunity contributes to SMA pathology. This work not only provides compelling evidence that hyperactive innate immune signaling is a primary effect of SMN depletion, but it also suggests that the SMN complex plays a regulatory role in this process in vivo. In summary, immune dysfunction in SMA is a consequence of reduced SMN levels and is driven by cellular and molecular mechanisms that are conserved between insects and mammals.
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Affiliation(s)
- Eric L Garcia
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Biology, University of Kentucky, Lexington, KY, USA
| | - Rebecca E Steiner
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- RNA Discovery and Lineberger Comprehensive Cancer Centers, University of North Carolina at Chapel Hill, Chapel Hill, 27599, USA
- Present Address: Lake, Erie College of Osteopathic Medicine, Bradenton, FL, USA
| | - Amanda C Raimer
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, 27599, USA
- Present Address, Radford University, Radford, VA, USA
| | - Laura E Herring
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - A Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, 27599, USA.
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, 27599, USA.
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, 27599, USA.
- RNA Discovery and Lineberger Comprehensive Cancer Centers, University of North Carolina at Chapel Hill, Chapel Hill, 27599, USA.
| | - Ashlyn M Spring
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC, 27402, USA.
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3
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Garcia EL, Steiner RE, Raimer AC, Herring LE, Matera AG, Spring AM. Dysregulation of innate immune signaling in animal models of Spinal Muscular Atrophy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.14.571739. [PMID: 38168196 PMCID: PMC10760185 DOI: 10.1101/2023.12.14.571739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Background Spinal Muscular Atrophy (SMA) is a devastating neuromuscular disease caused by hypomorphic loss of function in the Survival Motor Neuron (SMN) protein. SMA presents across broad spectrum of disease severity. Unfortunately, vertebrate models of intermediate SMA have been difficult to generate and are thus unable to address key aspects of disease etiology. To address these issues, we developed a Drosophila model system that recapitulates the full range of SMA severity, allowing studies of pre-onset biology as well as late-stage disease processes. Results Here, we carried out transcriptomic and proteomic profiling of mild and intermediate Drosophila models of SMA to elucidate molecules and pathways that contribute to the disease. Using this approach, we elaborated a role for the SMN complex in the regulation of innate immune signaling. We find that mutation or tissue-specific depletion of SMN induces hyperactivation of the Immune Deficiency (IMD) and Toll pathways, leading to overexpression of antimicrobial peptides (AMPs) and ectopic formation of melanotic masses in the absence of an external challenge. Furthermore, knockdown of downstream targets of these signaling pathways reduced melanotic mass formation caused by SMN loss. Importantly, we identify SMN as a negative regulator of an ubiquitylation complex that includes Traf6, Bendless and Diap2, and plays a pivotal role in several signaling networks. Conclusions In alignment with recent research on other neurodegenerative diseases, these findings suggest that hyperactivation of innate immunity contributes to SMA pathology. This work not only provides compelling evidence that hyperactive innate immune signaling is a primary effect of SMN depletion, but it also suggests that the SMN complex plays a regulatory role in this process in vivo. In summary, immune dysfunction in SMA is a consequence of reduced SMN levels and is driven by cellular and molecular mechanisms that are conserved between insects and mammals.
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Affiliation(s)
- Eric L. Garcia
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill NC, USA
- Department of Biology, University of Kentucky, Lexington KY, USA
| | - Rebecca E. Steiner
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill NC, USA
- Department of Biology, University of North Carolina at Chapel Hill
| | - Amanda C. Raimer
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill
| | - Laura E. Herring
- Department of Pharmacology, University of North Carolina at Chapel Hill
| | - A. Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill
- Department of Biology, University of North Carolina at Chapel Hill
- Department of Genetics, University of North Carolina at Chapel Hill
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill
| | - Ashlyn M. Spring
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill NC, USA
- Department of Biology, University of North Carolina at Greensboro, Greensboro NC, USA
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Liu Y, Iqbal A, Li W, Ni Z, Wang Y, Ramprasad J, Abraham KJ, Zhang M, Zhao DY, Qin S, Loppnau P, Jiang H, Guo X, Brown PJ, Zhen X, Xu G, Mekhail K, Ji X, Bedford MT, Greenblatt JF, Min J. A small molecule antagonist of SMN disrupts the interaction between SMN and RNAP II. Nat Commun 2022; 13:5453. [PMID: 36114190 PMCID: PMC9481570 DOI: 10.1038/s41467-022-33229-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 09/05/2022] [Indexed: 11/09/2022] Open
Abstract
Survival of motor neuron (SMN) functions in diverse biological pathways via recognition of symmetric dimethylarginine (Rme2s) on proteins by its Tudor domain, and deficiency of SMN leads to spinal muscular atrophy. Here we report a potent and selective antagonist with a 4-iminopyridine scaffold targeting the Tudor domain of SMN. Our structural and mutagenesis studies indicate that both the aromatic ring and imino groups of compound 1 contribute to its selective binding to SMN. Various on-target engagement assays support that compound 1 specifically recognizes SMN in a cellular context and prevents the interaction of SMN with the R1810me2s of RNA polymerase II subunit POLR2A, resulting in transcription termination and R-loop accumulation mimicking SMN depletion. Thus, in addition to the antisense, RNAi and CRISPR/Cas9 techniques, potent SMN antagonists could be used as an efficient tool to understand the biological functions of SMN.
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Affiliation(s)
- Yanli Liu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China.
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, China.
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada.
| | - Aman Iqbal
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada
| | - Weiguo Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada
| | - Zuyao Ni
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Yalong Wang
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jurupula Ramprasad
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Karan Joshua Abraham
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Mengmeng Zhang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | | | - Su Qin
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada
- Life Science Research Center, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Peter Loppnau
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada
| | - Honglv Jiang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Xinghua Guo
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Peter J Brown
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada
| | - Xuechu Zhen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Guoqiang Xu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Karim Mekhail
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Xingyue Ji
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Mark T Bedford
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Jinrong Min
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, China.
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada.
- Department of Physiology, University of Toronto, Toronto, ON, Canada.
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5
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Veepaschit J, Viswanathan A, Bordonné R, Grimm C, Fischer U. Identification and structural analysis of the Schizosaccharomyces pombe SMN complex. Nucleic Acids Res 2021; 49:7207-7223. [PMID: 33754639 PMCID: PMC8287938 DOI: 10.1093/nar/gkab158] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/11/2021] [Accepted: 02/26/2021] [Indexed: 01/20/2023] Open
Abstract
The macromolecular SMN complex facilitates the formation of Sm-class ribonucleoproteins involved in mRNA processing (UsnRNPs). While biochemical studies have revealed key activities of the SMN complex, its structural investigation is lagging behind. Here we report on the identification and structural determination of the SMN complex from the lower eukaryote Schizosaccharomyces pombe, consisting of SMN, Gemin2, 6, 7, 8 and Sm proteins. The core of the SMN complex is formed by several copies of SMN tethered through its C-terminal alpha-helices arranged with alternating polarity. This creates a central platform onto which Gemin8 binds and recruits Gemins 6 and 7. The N-terminal parts of the SMN molecules extrude via flexible linkers from the core and enable binding of Gemin2 and Sm proteins. Our data identify the SMN complex as a multivalent hub where Sm proteins are collected in its periphery to allow their joining with UsnRNA.
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Affiliation(s)
- Jyotishman Veepaschit
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg 97074, Germany
| | - Aravindan Viswanathan
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg 97074, Germany
| | - Rémy Bordonné
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier 34293, France
| | - Clemens Grimm
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg 97074, Germany
| | - Utz Fischer
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg 97074, Germany
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6
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Gupta K, Wen Y, Ninan NS, Raimer AC, Sharp R, Spring A, Sarachan KL, Johnson MC, Van Duyne GD, Matera AG. Assembly of higher-order SMN oligomers is essential for metazoan viability and requires an exposed structural motif present in the YG zipper dimer. Nucleic Acids Res 2021; 49:7644-7664. [PMID: 34181727 PMCID: PMC8287954 DOI: 10.1093/nar/gkab508] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
Protein oligomerization is one mechanism by which homogenous solutions can separate into distinct liquid phases, enabling assembly of membraneless organelles. Survival Motor Neuron (SMN) is the eponymous component of a large macromolecular complex that chaperones biogenesis of eukaryotic ribonucleoproteins and localizes to distinct membraneless organelles in both the nucleus and cytoplasm. SMN forms the oligomeric core of this complex, and missense mutations within its YG box domain are known to cause Spinal Muscular Atrophy (SMA). The SMN YG box utilizes a unique variant of the glycine zipper motif to form dimers, but the mechanism of higher-order oligomerization remains unknown. Here, we use a combination of molecular genetic, phylogenetic, biophysical, biochemical and computational approaches to show that formation of higher-order SMN oligomers depends on a set of YG box residues that are not involved in dimerization. Mutation of key residues within this new structural motif restricts assembly of SMN to dimers and causes locomotor dysfunction and viability defects in animal models.
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Affiliation(s)
- Kushol Gupta
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Ying Wen
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Nisha S Ninan
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Amanda C Raimer
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert Sharp
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Ashlyn M Spring
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kathryn L Sarachan
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Meghan C Johnson
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Gregory D Van Duyne
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - A Gregory Matera
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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7
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Blatnik AJ, McGovern VL, Le TT, Iyer CC, Kaspar BK, Burghes AHM. Conditional deletion of SMN in cell culture identifies functional SMN alleles. Hum Mol Genet 2020; 29:3477-3492. [PMID: 33075805 DOI: 10.1093/hmg/ddaa229] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/01/2020] [Accepted: 10/12/2020] [Indexed: 12/31/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by mutation or deletion of survival motor neuron 1 (SMN1) and retention of SMN2 leading to SMN protein deficiency. We developed an immortalized mouse embryonic fibroblast (iMEF) line in which full-length wild-type Smn (flwt-Smn) can be conditionally deleted using Cre recombinase. iMEFs lacking flwt-Smn are not viable. We tested the SMA patient SMN1 missense mutation alleles A2G, D44V, A111G, E134K and T274I in these cells to determine which human SMN (huSMN) mutant alleles can function in the absence of flwt-Smn. All missense mutant alleles failed to rescue survival in the conditionally deleted iMEFs. Thus, the function lost by these mutations is essential to cell survival. However, co-expression of two different huSMN missense mutants can rescue iMEF survival and small nuclear ribonucleoprotein (snRNP) assembly, demonstrating intragenic complementation of SMN alleles. In addition, we show that a Smn protein lacking exon 2B can rescue iMEF survival and snRNP assembly in the absence of flwt-Smn, indicating exon 2B is not required for the essential function of Smn. For the first time, using this novel cell line, we can assay the function of SMN alleles in the complete absence of flwt-Smn.
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Affiliation(s)
- Anton J Blatnik
- Ohio State Biochemistry Program.,Biological Chemistry & Pharmacology
| | | | | | | | - Brian K Kaspar
- Center for Gene Therapy, Nationwide Children's Hospital; Department of Pediatrics, College of Medicine and Public Health, The Ohio State University; and Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
| | - Arthur H M Burghes
- Ohio State Biochemistry Program.,Biological Chemistry & Pharmacology.,Molecular Genetics.,Department of Neurology, The Ohio State University Wexner Medical Center, Columbus OH 43210 USA
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8
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Maccallini P, Bavasso F, Scatolini L, Bucciarelli E, Noviello G, Lisi V, Palumbo V, D'Angeli S, Cacchione S, Cenci G, Ciapponi L, Wakefield JG, Gatti M, Raffa GD. Intimate functional interactions between TGS1 and the Smn complex revealed by an analysis of the Drosophila eye development. PLoS Genet 2020; 16:e1008815. [PMID: 32453722 PMCID: PMC7289441 DOI: 10.1371/journal.pgen.1008815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/11/2020] [Accepted: 04/30/2020] [Indexed: 11/27/2022] Open
Abstract
Trimethylguanosine synthase 1 (TGS1) is a conserved enzyme that mediates formation of the trimethylguanosine cap on several RNAs, including snRNAs and telomerase RNA. Previous studies have shown that TGS1 binds the Survival Motor Neuron (SMN) protein, whose deficiency causes spinal muscular atrophy (SMA). Here, we analyzed the roles of the Drosophila orthologs of the human TGS1 and SMN genes. We show that the Drosophila TGS1 protein (dTgs1) physically interacts with all subunits of the Drosophila Smn complex (Smn, Gem2, Gem3, Gem4 and Gem5), and that a human TGS1 transgene rescues the mutant phenotype caused by dTgs1 loss. We demonstrate that both dTgs1 and Smn are required for viability of retinal progenitor cells and that downregulation of these genes leads to a reduced eye size. Importantly, overexpression of dTgs1 partially rescues the eye defects caused by Smn depletion, and vice versa. These results suggest that the Drosophila eye model can be exploited for screens aimed at the identification of genes and drugs that modify the phenotypes elicited by Tgs1 and Smn deficiency. These modifiers could help to understand the molecular mechanisms underlying SMA pathogenesis and devise new therapies for this genetic disease. We explored the functional relationships between TGS1 and SMN using Drosophila as model organism. TGS1 is an enzyme that modifies the structure of the 5’-end of several RNAs, including telomerase RNA and the small nuclear RNAs (snRNAs) that are required for messenger RNA maturation. The SMN protein regulates snRNAs biogenesis and mutations in human SMN cause Spinal Muscular Atrophy (SMA), a devastating disorder characterized by neurodegeneration, progressive paralysis and death. We show that mutations in the Drosophila TGS1 (dTgs1) gene cause lethality, which is rescued by a human TGS1 transgene. We also show that the dTgs1 protein physically interacts with all subunits of the Smn complex, and that downregulation of either dTgs1 or Smn leads to a reduced Drosophila eye size. Notably, overexpression of dTgs1 partially rescues the eye defects caused by Smn knockdown, and vice versa, indicating that these genes cooperate in eye development. These results suggest that the eye model can be exploited for screens aimed at detection of chemical and genetic modifiers of the eye mutant phenotype elicited by dTgs1 and Smn deficiency, providing new clues about SMA pathogenesis and potential therapies.
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Affiliation(s)
- Paolo Maccallini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Livia Scatolini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | | | - Gemma Noviello
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Veronica Lisi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Simone D'Angeli
- Dipartimento di Biologia Ambientale, Sapienza University of Rome, Rome, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Giovanni Cenci
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Fondazione Cenci Bolognetti, Istituto Pasteur, Rome, Italy
| | - Laura Ciapponi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - James G. Wakefield
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, United Kingdom
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Rome, Italy
- * E-mail: (MG); (GDR)
| | - Grazia Daniela Raffa
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- * E-mail: (MG); (GDR)
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9
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Raimer AC, Singh SS, Edula MR, Paris-Davila T, Vandadi V, Spring AM, Matera AG. Temperature-sensitive spinal muscular atrophy-causing point mutations lead to SMN instability, locomotor defects and premature lethality in Drosophila. Dis Model Mech 2020; 13:dmm043307. [PMID: 32501283 PMCID: PMC7325441 DOI: 10.1242/dmm.043307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/18/2020] [Indexed: 12/15/2022] Open
Abstract
Spinal muscular atrophy (SMA) is the leading genetic cause of death in young children, arising from homozygous deletion or mutation of the survival motor neuron 1 (SMN1) gene. SMN protein expressed from a paralogous gene, SMN2, is the primary genetic modifier of SMA; small changes in overall SMN levels cause dramatic changes in disease severity. Thus, deeper insight into mechanisms that regulate SMN protein stability should lead to better therapeutic outcomes. Here, we show that SMA patient-derived missense mutations in the Drosophila SMN Tudor domain exhibit a pronounced temperature sensitivity that affects organismal viability, larval locomotor function and adult longevity. These disease-related phenotypes are domain specific and result from decreased SMN stability at elevated temperature. This system was utilized to manipulate SMN levels during various stages of Drosophila development. Owing to a large maternal contribution of mRNA and protein, Smn is not expressed zygotically during embryogenesis. Interestingly, we find that only baseline levels of SMN are required during larval stages, whereas high levels of the protein are required during pupation. This previously uncharacterized period of elevated SMN expression, during which the majority of adult tissues are formed and differentiated, could be an important and translationally relevant developmental stage in which to study SMN function. Taken together, these findings illustrate a novel in vivo role for the SMN Tudor domain in maintaining SMN homeostasis and highlight the necessity for high SMN levels at crucial developmental time points that are conserved from Drosophila to humans.
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Affiliation(s)
- Amanda C Raimer
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Suhana S Singh
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Maina R Edula
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Tamara Paris-Davila
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Vasudha Vandadi
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Ashlyn M Spring
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - A Gregory Matera
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
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10
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Osman EY, Bolding MR, Villalón E, Kaifer KA, Lorson ZC, Tisdale S, Hao Y, Conant GC, Pires JC, Pellizzoni L, Lorson CL. Functional characterization of SMN evolution in mouse models of SMA. Sci Rep 2019; 9:9472. [PMID: 31263170 PMCID: PMC6603021 DOI: 10.1038/s41598-019-45822-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 06/11/2019] [Indexed: 12/13/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is a monogenic neurodegenerative disorder and the leading genetic cause of infantile mortality. While several functions have been ascribed to the SMN (survival motor neuron) protein, their specific contribution to the disease has yet to be fully elucidated. We hypothesized that some, but not all, SMN homologues would rescue the SMA phenotype in mouse models, thereby identifying disease-relevant domains. Using AAV9 to deliver Smn homologs to SMA mice, we identified a conservation threshold that marks the boundary at which homologs can rescue the SMA phenotype. Smn from Danio rerio and Xenopus laevis significantly prevent disease, whereas Smn from Drosophila melanogaster, Caenorhabditis elegans, and Schizosaccharomyces pombe was significantly less efficacious. This phenotypic rescue correlated with correction of RNA processing defects induced by SMN deficiency and neuromuscular junction pathology. Based upon the sequence conservation in the rescuing homologs, a minimal SMN construct was designed consisting of exons 2, 3, and 6, which showed a partial rescue of the SMA phenotype. While a significant extension in survival was observed, the absence of a complete rescue suggests that while the core conserved region is essential, additional sequences contribute to the overall ability of the SMN protein to rescue disease pathology.
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Affiliation(s)
- Erkan Y Osman
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, 65211, USA.,Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Madeline R Bolding
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, 65211, USA.,Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Eric Villalón
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, 65211, USA.,Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Kevin A Kaifer
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, 65211, USA.,Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Zachary C Lorson
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, 65211, USA.,Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Sarah Tisdale
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - Yue Hao
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC, 27695, USA
| | - Gavin C Conant
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC, 27695, USA.,Division of Animal Sciences, University of Missouri, Columbia, MO, 65211, USA.,Division of Biological Sciences, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - J Chris Pires
- Department of Biological Sciences, Program in Genetics, North Carolina State University, Raleigh, NC, 27695, USA
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - Christian L Lorson
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, 65211, USA. .,Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA.
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11
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Ismail JN, Badini S, Frey F, Abou-Kheir W, Shirinian M. Drosophila Tet Is Expressed in Midline Glia and Is Required for Proper Axonal Development. Front Cell Neurosci 2019; 13:252. [PMID: 31213988 PMCID: PMC6558204 DOI: 10.3389/fncel.2019.00252] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/20/2019] [Indexed: 01/10/2023] Open
Abstract
Ten-Eleven Translocation (TET) proteins are important epigenetic regulators that play a key role in development and are frequently deregulated in cancer. Drosophila melanogaster has a single homologous Tet gene (dTet) that is highly expressed in the central nervous system during development. Here, we examined the expression pattern of dTet in the third instar larval CNS and discovered its presence in a specific set of glia cells: midline glia (MG). Moreover, dTet knockdown resulted in significant lethality, locomotor dysfunction, and alterations in axon patterning in the larval ventral nerve cord. Molecular analyses on dTet knockdown larvae showed a downregulation in genes involved in axon guidance and reduced expression of the axon guidance cue Slit. Our findings point toward a potential role for dTet in midline glial function, specifically the regulation of axon patterning during neurodevelopment.
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Affiliation(s)
- Joy N Ismail
- Department of Experimental Pathology and Immunology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,Center for Infectious Diseases Research, American University of Beirut Medical Center, Beirut, Lebanon
| | - Shireen Badini
- Department of Experimental Pathology and Immunology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,Center for Infectious Diseases Research, American University of Beirut Medical Center, Beirut, Lebanon
| | - Felice Frey
- Department of Experimental Pathology and Immunology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,Center for Infectious Diseases Research, American University of Beirut Medical Center, Beirut, Lebanon
| | - Wassim Abou-Kheir
- Department of Anatomy, Cell Biology, and Physiological Sciences, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Margret Shirinian
- Department of Experimental Pathology and Immunology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,Center for Infectious Diseases Research, American University of Beirut Medical Center, Beirut, Lebanon
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12
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Spring AM, Raimer AC, Hamilton CD, Schillinger MJ, Matera AG. Comprehensive Modeling of Spinal Muscular Atrophy in Drosophila melanogaster. Front Mol Neurosci 2019; 12:113. [PMID: 31156382 PMCID: PMC6532329 DOI: 10.3389/fnmol.2019.00113] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 04/18/2019] [Indexed: 01/02/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disorder that affects motor neurons, primarily in young children. SMA is caused by mutations in the Survival Motor Neuron 1 (SMN1) gene. SMN functions in the assembly of spliceosomal RNPs and is well conserved in many model systems including mouse, zebrafish, fruit fly, nematode, and fission yeast. Work in Drosophila has focused on the loss of SMN function during larval stages, primarily using null alleles or strong hypomorphs. A systematic analysis of SMA-related phenotypes in the context of moderate alleles that more closely mimic the genetics of SMA has not been performed in the fly, leading to debate over the validity and translational value of this model. We, therefore, examined 14 Drosophila lines expressing SMA patient-derived missense mutations in Smn, with a focus on neuromuscular phenotypes in the adult stage. Animals were evaluated on the basis of organismal viability and longevity, locomotor function, neuromuscular junction structure, and muscle health. In all cases, we observed phenotypes similar to those of SMA patients, including progressive loss of adult motor function. The severity of these defects is variable and forms a broad spectrum across the 14 lines examined, recapitulating the full range of phenotypic severity observed in human SMA. This includes late-onset models of SMA, which have been difficult to produce in other model systems. The results provide direct evidence that SMA-related locomotor decline can be reproduced in the fly and support the use of patient-derived SMN missense mutations as a comprehensive system for modeling SMA.
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Affiliation(s)
- Ashlyn M. Spring
- Integrative Program in Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, United States
| | - Amanda C. Raimer
- Integrative Program in Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, United States
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, United States
| | - Christine D. Hamilton
- Integrative Program in Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, United States
| | | | - A. Gregory Matera
- Integrative Program in Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, United States
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, United States
- Department of Biology, University of North Carolina, Chapel Hill, NC, United States
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States
- Department of Genetics, University of North Carolina, Chapel Hill, NC, United States
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13
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Gao X, Xu J, Chen H, Xue D, Pan W, Zhou C, Ma YC, Ma L. Defective Expression of Mitochondrial, Vacuolar H +-ATPase and Histone Genes in a C. elegans Model of SMA. Front Genet 2019; 10:410. [PMID: 31130987 PMCID: PMC6509145 DOI: 10.3389/fgene.2019.00410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 04/15/2019] [Indexed: 12/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a severe motor neuron degenerative disease caused by loss-of-function mutations in the survival motor neuron gene SMN1. It is widely posited that defective gene expression underlies SMA. However, the identities of these affected genes remain to be elucidated. By analyzing the transcriptome of a Caenorhabditis elegans SMA model at the pre-symptomatic stage, we found that the expression of numerous nuclear encoded mitochondrial genes and vacuolar H+-ATPase genes was significantly down-regulated, while that of histone genes was significantly up-regulated. We previously showed that the uaf-1 gene, encoding key splicing factor U2AF large subunit, could affect the behavior and lifespan of smn-1 mutants. Here, we found that smn-1 and uaf-1 interact to affect the recognition of 3′ and 5′ splice sites in a gene-specific manner. Altogether, our results suggest a functional interaction between smn-1 and uaf-1 in affecting RNA splicing and a potential effect of smn-1 on the expression of mitochondrial and histone genes.
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Affiliation(s)
- Xiaoyang Gao
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Jing Xu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Hao Chen
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Dingwu Xue
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Wenju Pan
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Chuanman Zhou
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Yongchao C Ma
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, United States
| | - Long Ma
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
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14
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Composition of the Survival Motor Neuron (SMN) Complex in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2019; 9:491-503. [PMID: 30563832 PMCID: PMC6385987 DOI: 10.1534/g3.118.200874] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Spinal Muscular Atrophy (SMA) is caused by homozygous mutations in the human survival motor neuron 1 (SMN1) gene. SMN protein has a well-characterized role in the biogenesis of small nuclear ribonucleoproteins (snRNPs), core components of the spliceosome. SMN is part of an oligomeric complex with core binding partners, collectively called Gemins. Biochemical and cell biological studies demonstrate that certain Gemins are required for proper snRNP assembly and transport. However, the precise functions of most Gemins are unknown. To gain a deeper understanding of the SMN complex in the context of metazoan evolution, we investigated its composition in Drosophila melanogaster Using transgenic flies that exclusively express Flag-tagged SMN from its native promoter, we previously found that Gemin2, Gemin3, Gemin5, and all nine classical Sm proteins, including Lsm10 and Lsm11, co-purify with SMN. Here, we show that CG2941 is also highly enriched in the pulldown. Reciprocal co-immunoprecipitation reveals that epitope-tagged CG2941 interacts with endogenous SMN in Schneider2 cells. Bioinformatic comparisons show that CG2941 shares sequence and structural similarity with metazoan Gemin4. Additional analysis shows that three other genes (CG14164, CG31950 and CG2371) are not orthologous to Gemins 6-7-8, respectively, as previously suggested. In D.melanogaster, CG2941 is located within an evolutionarily recent genomic triplication with two other nearly identical paralogous genes (CG32783 and CG32786). RNAi-mediated knockdown of CG2941 and its two close paralogs reveals that Gemin4 is essential for organismal viability.
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15
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Aquilina B, Cauchi RJ. Modelling motor neuron disease in fruit flies: Lessons from spinal muscular atrophy. J Neurosci Methods 2018; 310:3-11. [DOI: 10.1016/j.jneumeth.2018.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 04/06/2018] [Accepted: 04/07/2018] [Indexed: 12/25/2022]
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16
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Banerjee S, Riordan M. Coordinated Regulation of Axonal Microtubule Organization and Transport by Drosophila Neurexin and BMP Pathway. Sci Rep 2018; 8:17337. [PMID: 30478335 PMCID: PMC6255869 DOI: 10.1038/s41598-018-35618-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/07/2018] [Indexed: 01/23/2023] Open
Abstract
Neurexins are well known trans-synaptic cell adhesion molecules that are required for proper synaptic development and function across species. Beyond synapse organization and function, little is known about other roles Neurexins might have in the nervous system. Here we report novel phenotypic consequences of mutations in Drosophila neurexin (dnrx), which alters axonal microtubule organization and transport. We show that dnrx mutants display phenotypic similarities with the BMP receptor wishful thinking (wit) and one of the downstream effectors, futsch, which is a known regulator of microtubule organization and stability. dnrx has genetic interactions with wit and futsch. Loss of Dnrx also results in reduced levels of other downstream effectors of BMP signaling, phosphorylated-Mad and Trio. Interestingly, postsynaptic overexpression of the BMP ligand, Glass bottom boat, in dnrx mutants partially rescues the axonal transport defects but not the synapse undergrowth at the neuromuscular junctions. These data suggest that Dnrx and BMP signaling are involved in many diverse functions and that regulation of axonal MT organization and transport might be distinct from regulation of synaptic growth in dnrx mutants. Together, our work uncovers a novel function of Drosophila Neurexin and may provide insights into functions of Neurexins in vertebrates.
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Affiliation(s)
- Swati Banerjee
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.
| | - Maeveen Riordan
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.,University of Colorado School of Medicine, 12631 E. 17th Avenue B177, Aurora, CO, 80045, USA
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17
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Olesnicky EC, Wright EG. Drosophila as a Model for Assessing the Function of RNA-Binding Proteins during Neurogenesis and Neurological Disease. J Dev Biol 2018; 6:E21. [PMID: 30126171 PMCID: PMC6162566 DOI: 10.3390/jdb6030021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/15/2018] [Accepted: 08/15/2018] [Indexed: 12/16/2022] Open
Abstract
An outstanding question in developmental neurobiology is how RNA processing events contribute to the regulation of neurogenesis. RNA processing events are increasingly recognized as playing fundamental roles in regulating multiple developmental events during neurogenesis, from the asymmetric divisions of neural stem cells, to the generation of complex and diverse neurite morphologies. Indeed, both asymmetric cell division and neurite morphogenesis are often achieved by mechanisms that generate asymmetric protein distributions, including post-transcriptional gene regulatory mechanisms such as the transport of translationally silent messenger RNAs (mRNAs) and local translation of mRNAs within neurites. Additionally, defects in RNA splicing have emerged as a common theme in many neurodegenerative disorders, highlighting the importance of RNA processing in maintaining neuronal circuitry. RNA-binding proteins (RBPs) play an integral role in splicing and post-transcriptional gene regulation, and mutations in RBPs have been linked with multiple neurological disorders including autism, dementia, amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Fragile X syndrome (FXS), and X-linked intellectual disability disorder. Despite their widespread nature and roles in neurological disease, the molecular mechanisms and networks of regulated target RNAs have been defined for only a small number of specific RBPs. This review aims to highlight recent studies in Drosophila that have advanced our knowledge of how RBP dysfunction contributes to neurological disease.
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Affiliation(s)
- Eugenia C Olesnicky
- Department of Biology, University of Colorado Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918, USA.
| | - Ethan G Wright
- Department of Biology, University of Colorado Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918, USA.
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18
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Khalil B, Morderer D, Price PL, Liu F, Rossoll W. mRNP assembly, axonal transport, and local translation in neurodegenerative diseases. Brain Res 2018; 1693:75-91. [PMID: 29462608 PMCID: PMC5997521 DOI: 10.1016/j.brainres.2018.02.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/31/2018] [Accepted: 02/13/2018] [Indexed: 12/12/2022]
Abstract
The development, maturation, and maintenance of the mammalian nervous system rely on complex spatiotemporal patterns of gene expression. In neurons, this is achieved by the expression of differentially localized isoforms and specific sets of mRNA-binding proteins (mRBPs) that regulate RNA processing, mRNA trafficking, and local protein synthesis at remote sites within dendrites and axons. There is growing evidence that axons contain a specialized transcriptome and are endowed with the machinery that allows them to rapidly alter their local proteome via local translation and protein degradation. This enables axons to quickly respond to changes in their environment during development, and to facilitate axon regeneration and maintenance in adult organisms. Aside from providing autonomy to neuronal processes, local translation allows axons to send retrograde injury signals to the cell soma. In this review, we discuss evidence that disturbances in mRNP transport, granule assembly, axonal localization, and local translation contribute to pathology in various neurodegenerative diseases, including spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Alzheimer's disease (AD).
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Affiliation(s)
- Bilal Khalil
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Dmytro Morderer
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Phillip L Price
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA; Department of Cell Biology, Emory University, Atlanta, GA 30322 USA
| | - Feilin Liu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA; Eye Center, The Second Hospital of Jilin University, Changchun, Jilin 130021, China
| | - Wilfried Rossoll
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA.
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19
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Bowerman M, Becker CG, Yáñez-Muñoz RJ, Ning K, Wood MJA, Gillingwater TH, Talbot K. Therapeutic strategies for spinal muscular atrophy: SMN and beyond. Dis Model Mech 2018; 10:943-954. [PMID: 28768735 PMCID: PMC5560066 DOI: 10.1242/dmm.030148] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder characterized by loss of motor neurons and muscle atrophy, generally presenting in childhood. SMA is caused by low levels of the survival motor neuron protein (SMN) due to inactivating mutations in the encoding gene SMN1. A second duplicated gene, SMN2, produces very little but sufficient functional protein for survival. Therapeutic strategies to increase SMN are in clinical trials, and the first SMN2-directed antisense oligonucleotide (ASO) therapy has recently been licensed. However, several factors suggest that complementary strategies may be needed for the long-term maintenance of neuromuscular and other functions in SMA patients. Pre-clinical SMA models demonstrate that the requirement for SMN protein is highest when the structural connections of the neuromuscular system are being established, from late fetal life throughout infancy. Augmenting SMN may not address the slow neurodegenerative process underlying progressive functional decline beyond childhood in less severe types of SMA. Furthermore, individuals receiving SMN-based treatments may be vulnerable to delayed symptoms if rescue of the neuromuscular system is incomplete. Finally, a large number of older patients living with SMA do not fulfill the present criteria for inclusion in gene therapy and ASO clinical trials, and may not benefit from SMN-inducing treatments. Therefore, a comprehensive whole-lifespan approach to SMA therapy is required that includes both SMN-dependent and SMN-independent strategies that treat the CNS and periphery. Here, we review the range of non-SMN pathways implicated in SMA pathophysiology and discuss how various model systems can serve as valuable tools for SMA drug discovery. Summary: Translational research for spinal muscular atrophy (SMA) should address the development of non-CNS and survival motor neuron (SMN)-independent therapeutic approaches to complement and enhance the benefits of CNS-directed and SMN-dependent therapies.
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Affiliation(s)
- Melissa Bowerman
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Catherina G Becker
- Euan MacDonald Centre for Motor Neurone Disease Research and Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Rafael J Yáñez-Muñoz
- AGCTlab.org, Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway, University of London, Egham Hill, Egham, Surrey TW20 0EX, UK
| | - Ke Ning
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, UK
| | - Matthew J A Wood
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research and Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Kevin Talbot
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
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20
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Gray KM, Kaifer KA, Baillat D, Wen Y, Bonacci TR, Ebert AD, Raimer AC, Spring AM, Have ST, Glascock JJ, Gupta K, Van Duyne GD, Emanuele MJ, Lamond AI, Wagner EJ, Lorson CL, Matera AG. Self-oligomerization regulates stability of survival motor neuron protein isoforms by sequestering an SCF Slmb degron. Mol Biol Cell 2018; 29:96-110. [PMID: 29167380 PMCID: PMC5909936 DOI: 10.1091/mbc.e17-11-0627] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 11/14/2017] [Indexed: 12/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by homozygous mutations in human SMN1 Expression of a duplicate gene (SMN2) primarily results in skipping of exon 7 and production of an unstable protein isoform, SMNΔ7. Although SMN2 exon skipping is the principal contributor to SMA severity, mechanisms governing stability of survival motor neuron (SMN) isoforms are poorly understood. We used a Drosophila model system and label-free proteomics to identify the SCFSlmb ubiquitin E3 ligase complex as a novel SMN binding partner. SCFSlmb interacts with a phosphor degron embedded within the human and fruitfly SMN YG-box oligomerization domains. Substitution of a conserved serine (S270A) interferes with SCFSlmb binding and stabilizes SMNΔ7. SMA-causing missense mutations that block multimerization of full-length SMN are also stabilized in the degron mutant background. Overexpression of SMNΔ7S270A, but not wild-type (WT) SMNΔ7, provides a protective effect in SMA model mice and human motor neuron cell culture systems. Our findings support a model wherein the degron is exposed when SMN is monomeric and sequestered when SMN forms higher-order multimers.
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Affiliation(s)
- Kelsey M Gray
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Kevin A Kaifer
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - David Baillat
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77550
| | - Ying Wen
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Thomas R Bonacci
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599
| | - Allison D Ebert
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Amanda C Raimer
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Ashlyn M Spring
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Sara Ten Have
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD15EH, UK
| | - Jacqueline J Glascock
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - Kushol Gupta
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Gregory D Van Duyne
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Michael J Emanuele
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599
| | - Angus I Lamond
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD15EH, UK
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77550
| | - Christian L Lorson
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - A Gregory Matera
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
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21
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Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease caused by mutations/deletions within the survival of motor neuron 1 (SMN1) gene that lead to a pathological reduction of SMN protein levels. SMN is part of a multiprotein complex, functioning as a molecular chaperone that facilitates the assembly of spliceosomal small nuclear ribonucleoproteins (snRNP). In addition to its role in spliceosome formation, SMN has also been found to interact with mRNA-binding proteins (mRBPs), and facilitate their assembly into mRNP transport granules. The association of protein and RNA in RNP complexes plays an important role in an extensive and diverse set of cellular processes that regulate neuronal growth, differentiation, and the maturation and plasticity of synapses. This review discusses the role of SMN in RNP assembly and localization, focusing on molecular defects that affect mRNA processing and may contribute to SMA pathology.
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22
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Lanfranco M, Cacciottolo R, Borg RM, Vassallo N, Juge F, Bordonné R, Cauchi RJ. Novel interactors of the Drosophila
Survival Motor Neuron (SMN) Complex suggest its full conservation. FEBS Lett 2017; 591:3600-3614. [DOI: 10.1002/1873-3468.12853] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/14/2017] [Accepted: 09/14/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Maia Lanfranco
- Institut de Génétique Moléculaire de Montpellier; CNRS-UMR 5535; Université de Montpellier; France
- Department of Physiology and Biochemistry; Faculty of Medicine and Surgery; University of Malta; Msida Malta
- Centre for Molecular Medicine and Biobanking; University of Malta; Msida Malta
| | - Rebecca Cacciottolo
- Department of Physiology and Biochemistry; Faculty of Medicine and Surgery; University of Malta; Msida Malta
- Centre for Molecular Medicine and Biobanking; University of Malta; Msida Malta
| | - Rebecca M. Borg
- Institut de Génétique Moléculaire de Montpellier; CNRS-UMR 5535; Université de Montpellier; France
- Department of Physiology and Biochemistry; Faculty of Medicine and Surgery; University of Malta; Msida Malta
- Centre for Molecular Medicine and Biobanking; University of Malta; Msida Malta
| | - Neville Vassallo
- Department of Physiology and Biochemistry; Faculty of Medicine and Surgery; University of Malta; Msida Malta
- Centre for Molecular Medicine and Biobanking; University of Malta; Msida Malta
| | - François Juge
- Institut de Génétique Moléculaire de Montpellier; CNRS-UMR 5535; Université de Montpellier; France
| | - Rémy Bordonné
- Institut de Génétique Moléculaire de Montpellier; CNRS-UMR 5535; Université de Montpellier; France
| | - Ruben J. Cauchi
- Department of Physiology and Biochemistry; Faculty of Medicine and Surgery; University of Malta; Msida Malta
- Centre for Molecular Medicine and Biobanking; University of Malta; Msida Malta
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23
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Dominguez CE, Cunningham D, Chandler DS. SMN regulation in SMA and in response to stress: new paradigms and therapeutic possibilities. Hum Genet 2017; 136:1173-1191. [PMID: 28852871 PMCID: PMC6201753 DOI: 10.1007/s00439-017-1835-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 08/07/2017] [Indexed: 12/12/2022]
Abstract
Low levels of the survival of motor neuron (SMN) protein cause the neurodegenerative disease spinal muscular atrophy (SMA). SMA is a pediatric disease characterized by spinal motor neuron degeneration. SMA exhibits several levels of severity ranging from early antenatal fatality to only mild muscular weakness, and disease prognosis is related directly to the amount of functional SMN protein that a patient is able to express. Current therapies are being developed to increase the production of functional SMN protein; however, understanding the effect that natural stresses have on the production and function of SMN is of critical importance to ensuring that these therapies will have the greatest possible effect for patients. Research has shown that SMN, both on the mRNA and protein level, is highly affected by cellular stress. In this review we will summarize the research that highlights the roles of SMN in the disease process and the response of SMN to various environmental stresses.
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Affiliation(s)
- Catherine E Dominguez
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA
| | - David Cunningham
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA
| | - Dawn S Chandler
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA.
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA.
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24
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Prusty AB, Meduri R, Prusty BK, Vanselow J, Schlosser A, Fischer U. Impaired spliceosomal UsnRNP assembly leads to Sm mRNA down-regulation and Sm protein degradation. J Cell Biol 2017. [PMID: 28637748 PMCID: PMC5551706 DOI: 10.1083/jcb.201611108] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cellular spliceosomal UsnRNP assembly is assisted by the PRMT5 and SMN complexes. Prusty et al. demonstrate that perturbations in the assembly machinery of UsnRNPs trigger complex cellular responses, using ribosomes, exosome-mediated RNA degradation, and autophagy to prevent Sm protein aggregation. Specialized assembly factors facilitate the formation of many macromolecular complexes in vivo. The formation of Sm core structures of spliceosomal U-rich small nuclear ribonucleoprotein particles (UsnRNPs) requires assembly factors united in protein arginine methyltransferase 5 (PRMT5) and survival motor neuron (SMN) complexes. We demonstrate that perturbations of this assembly machinery trigger complex cellular responses that prevent aggregation of unassembled Sm proteins. Inactivation of the SMN complex results in the initial tailback of Sm proteins on the PRMT5 complex, followed by down-regulation of their encoding mRNAs. In contrast, reduction of pICln, a PRMT5 complex subunit, leads to the retention of newly synthesized Sm proteins on ribosomes and their subsequent lysosomal degradation. Overexpression of Sm proteins under these conditions results in a surplus of Sm proteins over pICln, promoting their aggregation. Our studies identify an elaborate safeguarding system that prevents individual Sm proteins from aggregating, contributing to cellular UsnRNP homeostasis.
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Affiliation(s)
| | - Rajyalakshmi Meduri
- Department of Biochemistry, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Bhupesh Kumar Prusty
- Department of Microbiology, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Jens Vanselow
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Andreas Schlosser
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Utz Fischer
- Department of Biochemistry, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany .,Department of Radiation Medicine and Applied Sciences, University of California at San Diego, San Diego, CA
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25
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Jablonka S, Sendtner M. Developmental regulation of SMN expression: pathophysiological implications and perspectives for therapy development in spinal muscular atrophy. Gene Ther 2017; 24:506-513. [DOI: 10.1038/gt.2017.46] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/16/2017] [Accepted: 05/19/2017] [Indexed: 12/18/2022]
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26
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Di Giorgio ML, Esposito A, Maccallini P, Micheli E, Bavasso F, Gallotta I, Vernì F, Feiguin F, Cacchione S, McCabe BD, Di Schiavi E, Raffa GD. WDR79/TCAB1 plays a conserved role in the control of locomotion and ameliorates phenotypic defects in SMA models. Neurobiol Dis 2017; 105:42-50. [PMID: 28502804 DOI: 10.1016/j.nbd.2017.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/19/2017] [Accepted: 05/10/2017] [Indexed: 12/22/2022] Open
Abstract
SMN (Survival Motor Neuron) deficiency is the predominant cause of spinal muscular atrophy (SMA), a severe neurodegenerative disorder that can lead to progressive paralysis and death. Although SMN is required in every cell for proper RNA metabolism, the reason why its loss is especially critical in the motor system is still unclear. SMA genetic models have been employed to identify several modifiers that can ameliorate the deficits induced by SMN depletion. Here we focus on WDR79/TCAB1, a protein important for the biogenesis of several RNA species that has been shown to physically interact with SMN in human cells. We show that WDR79 depletion results in locomotion defects in both Drosophila and Caenorhabditis elegans similar to those elicited by SMN depletion. Consistent with this observation, we find that SMN overexpression rescues the WDR79 loss-of-function phenotype in flies. Most importantly, we also found that WDR79 overexpression ameliorates the locomotion defects induced by SMN depletion in both flies and worms. Our results collectively suggest that WDR79 and SMN play evolutionarily conserved cooperative functions in the nervous system and suggest that WDR79/TCAB1 may have the potential to modify SMA pathogenesis.
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Affiliation(s)
- Maria Laura Di Giorgio
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Rome, Italy
| | | | - Paolo Maccallini
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Rome, Italy
| | - Emanuela Micheli
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Rome, Italy
| | - Francesca Bavasso
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Rome, Italy
| | - Ivan Gallotta
- Institute of Genetics and Biophysics - ABT, CNR, Naples, Italy
| | - Fiammetta Vernì
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Rome, Italy
| | - Fabian Feiguin
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Stefano Cacchione
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Rome, Italy
| | | | - Elia Di Schiavi
- Institute of Genetics and Biophysics - ABT, CNR, Naples, Italy; Institute of Bioscience and Bioresources, CNR, Naples, Italy
| | - Grazia Daniela Raffa
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Rome, Italy.
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27
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Jangi M, Fleet C, Cullen P, Gupta SV, Mekhoubad S, Chiao E, Allaire N, Bennett CF, Rigo F, Krainer AR, Hurt JA, Carulli JP, Staropoli JF. SMN deficiency in severe models of spinal muscular atrophy causes widespread intron retention and DNA damage. Proc Natl Acad Sci U S A 2017; 114:E2347-E2356. [PMID: 28270613 PMCID: PMC5373344 DOI: 10.1073/pnas.1613181114] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spinal muscular atrophy (SMA), an autosomal recessive neuromuscular disease, is the leading monogenic cause of infant mortality. Homozygous loss of the gene survival of motor neuron 1 (SMN1) causes the selective degeneration of lower motor neurons and subsequent atrophy of proximal skeletal muscles. The SMN1 protein product, survival of motor neuron (SMN), is ubiquitously expressed and is a key factor in the assembly of the core splicing machinery. The molecular mechanisms by which disruption of the broad functions of SMN leads to neurodegeneration remain unclear. We used an antisense oligonucleotide (ASO)-based inducible mouse model of SMA to investigate the SMN-specific transcriptome changes associated with neurodegeneration. We found evidence of widespread intron retention, particularly of minor U12 introns, in the spinal cord of mice 30 d after SMA induction, which was then rescued by a therapeutic ASO. Intron retention was concomitant with a strong induction of the p53 pathway and DNA damage response, manifesting as γ-H2A.X positivity in neurons of the spinal cord and brain. Widespread intron retention and markers of the DNA damage response were also observed with SMN depletion in human SH-SY5Y neuroblastoma cells and human induced pluripotent stem cell-derived motor neurons. We also found that retained introns, high in GC content, served as substrates for the formation of transcriptional R-loops. We propose that defects in intron removal in SMA promote DNA damage in part through the formation of RNA:DNA hybrid structures, leading to motor neuron death.
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Affiliation(s)
- Mohini Jangi
- Computational Biology & Genomics, Biogen, Cambridge, MA 02142
| | - Christina Fleet
- Computational Biology & Genomics, Biogen, Cambridge, MA 02142
| | - Patrick Cullen
- Computational Biology & Genomics, Biogen, Cambridge, MA 02142
| | - Shipra V Gupta
- Computational Biology & Genomics, Biogen, Cambridge, MA 02142
| | | | - Eric Chiao
- Stem Cell Research, Biogen, Cambridge, MA 02142
| | - Norm Allaire
- Computational Biology & Genomics, Biogen, Cambridge, MA 02142
| | - C Frank Bennett
- Neuroscience Drug Discovery, Ionis Pharmaceuticals, Carlsbad, CA 92008
| | - Frank Rigo
- Neuroscience Drug Discovery, Ionis Pharmaceuticals, Carlsbad, CA 92008
| | | | - Jessica A Hurt
- Computational Biology & Genomics, Biogen, Cambridge, MA 02142
| | - John P Carulli
- Computational Biology & Genomics, Biogen, Cambridge, MA 02142;
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28
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Singh RN, Howell MD, Ottesen EW, Singh NN. Diverse role of survival motor neuron protein. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2017; 1860:299-315. [PMID: 28095296 PMCID: PMC5325804 DOI: 10.1016/j.bbagrm.2016.12.008] [Citation(s) in RCA: 189] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 12/23/2016] [Accepted: 12/30/2016] [Indexed: 02/07/2023]
Abstract
The multifunctional Survival Motor Neuron (SMN) protein is required for the survival of all organisms of the animal kingdom. SMN impacts various aspects of RNA metabolism through the formation and/or interaction with ribonucleoprotein (RNP) complexes. SMN regulates biogenesis of small nuclear RNPs, small nucleolar RNPs, small Cajal body-associated RNPs, signal recognition particles and telomerase. SMN also plays an important role in DNA repair, transcription, pre-mRNA splicing, histone mRNA processing, translation, selenoprotein synthesis, macromolecular trafficking, stress granule formation, cell signaling and cytoskeleton maintenance. The tissue-specific requirement of SMN is dictated by the variety and the abundance of its interacting partners. Reduced expression of SMN causes spinal muscular atrophy (SMA), a leading genetic cause of infant mortality. SMA displays a broad spectrum ranging from embryonic lethality to an adult onset. Aberrant expression and/or localization of SMN has also been associated with male infertility, inclusion body myositis, amyotrophic lateral sclerosis and osteoarthritis. This review provides a summary of various SMN functions with implications to a better understanding of SMA and other pathological conditions.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
| | - Matthew D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
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29
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Gama-Carvalho M, L Garcia-Vaquero M, R Pinto F, Besse F, Weis J, Voigt A, Schulz JB, De Las Rivas J. Linking amyotrophic lateral sclerosis and spinal muscular atrophy through RNA-transcriptome homeostasis: a genomics perspective. J Neurochem 2017; 141:12-30. [PMID: 28054357 DOI: 10.1111/jnc.13945] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/02/2016] [Accepted: 12/24/2016] [Indexed: 12/11/2022]
Abstract
In this review, we present our most recent understanding of key biomolecular processes that underlie two motor neuron degenerative disorders, amyotrophic lateral sclerosis, and spinal muscular atrophy. We focus on the role of four multifunctional proteins involved in RNA metabolism (TDP-43, FUS, SMN, and Senataxin) that play a causal role in these diseases. Recent results have led to a novel scenario of intricate connections between these four proteins, bringing transcriptome homeostasis into the spotlight as a common theme in motor neuron degeneration. We review reported functional and physical interactions between these four proteins, highlighting their common association with nuclear bodies and small nuclear ribonucleoprotein particle biogenesis and function. We discuss how these interactions are turning out to be particularly relevant for the control of transcription and chromatin homeostasis, including the recent identification of an association between SMN and Senataxin required to ensure the resolution of DNA-RNA hybrid formation and proper termination by RNA polymerase II. These connections strongly support the existence of common pathways underlying the spinal muscular atrophy and amyotrophic lateral sclerosis phenotype. We also discuss the potential of genome-wide expression profiling, in particular RNA sequencing derived data, to contribute to unravelling the underlying mechanisms. We provide a review of publicly available datasets that have addressed both diseases using these approaches, and highlight the value of investing in cross-disease studies to promote our understanding of the pathways leading to neurodegeneration.
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Affiliation(s)
- Margarida Gama-Carvalho
- Universidade de Lisboa, Faculdade de Ciências, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisboa, Portugal
| | - Marina L Garcia-Vaquero
- Universidade de Lisboa, Faculdade de Ciências, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisboa, Portugal
| | - Francisco R Pinto
- Universidade de Lisboa, Faculdade de Ciências, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisboa, Portugal
| | | | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
| | - Aaron Voigt
- Department of Neurology, University Hospital, RWTH Aachen University, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Jörg B Schulz
- Department of Neurology, University Hospital, RWTH Aachen University, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Javier De Las Rivas
- Cancer Research Center (CiC-IBMCC, CSIC/USAL/IBSAL), Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca (USAL), Salamanca, Spain
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30
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Donlin-Asp PG, Fallini C, Campos J, Chou CC, Merritt ME, Phan HC, Bassell GJ, Rossoll W. The Survival of Motor Neuron Protein Acts as a Molecular Chaperone for mRNP Assembly. Cell Rep 2017; 18:1660-1673. [PMID: 28199839 PMCID: PMC5492976 DOI: 10.1016/j.celrep.2017.01.059] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/16/2016] [Accepted: 01/24/2017] [Indexed: 12/23/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease caused by reduced levels of the survival of motor neuron (SMN) protein. SMN is part of a multiprotein complex that facilitates the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). SMN has also been found to associate with mRNA-binding proteins, but the nature of this association was unknown. Here, we have employed a combination of biochemical and advanced imaging methods to demonstrate that SMN promotes the molecular interaction between IMP1 protein and the 3' UTR zipcode region of β-actin mRNA, leading to assembly of messenger ribonucleoprotein (mRNP) complexes that associate with the cytoskeleton to facilitate trafficking. We have identified defects in mRNP assembly in cells and tissues from SMA disease models and patients that depend on the SMN Tudor domain and explain the observed deficiency in mRNA localization and local translation, providing insight into SMA pathogenesis as a ribonucleoprotein (RNP)-assembly disorder.
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Affiliation(s)
- Paul G Donlin-Asp
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Claudia Fallini
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jazmin Campos
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ching-Chieh Chou
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Megan E Merritt
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Laboratory of Translational Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Han C Phan
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA; Laboratory of Translational Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Wilfried Rossoll
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA; Laboratory of Translational Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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31
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Hebert MD, Poole AR. Towards an understanding of regulating Cajal body activity by protein modification. RNA Biol 2016; 14:761-778. [PMID: 27819531 DOI: 10.1080/15476286.2016.1243649] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The biogenesis of small nuclear ribonucleoproteins (snRNPs), small Cajal body-specific RNPs (scaRNPs), small nucleolar RNPs (snoRNPs) and the telomerase RNP involves Cajal bodies (CBs). Although many components enriched in the CB contain post-translational modifications (PTMs), little is known about how these modifications impact individual protein function within the CB and, in concert with other modified factors, collectively regulate CB activity. Since all components of the CB also reside in other cellular locations, it is also important that we understand how PTMs affect the subcellular localization of CB components. In this review, we explore the current knowledge of PTMs on the activity of proteins known to enrich in CBs in an effort to highlight current progress as well as illuminate paths for future investigation.
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Affiliation(s)
- Michael D Hebert
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Aaron R Poole
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
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32
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Hosseinibarkooie S, Peters M, Torres-Benito L, Rastetter R, Hupperich K, Hoffmann A, Mendoza-Ferreira N, Kaczmarek A, Janzen E, Milbradt J, Lamkemeyer T, Rigo F, Bennett C, Guschlbauer C, Büschges A, Hammerschmidt M, Riessland M, Kye M, Clemen C, Wirth B. The Power of Human Protective Modifiers: PLS3 and CORO1C Unravel Impaired Endocytosis in Spinal Muscular Atrophy and Rescue SMA Phenotype. Am J Hum Genet 2016; 99:647-665. [PMID: 27499521 DOI: 10.1016/j.ajhg.2016.07.014] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 07/14/2016] [Indexed: 12/13/2022] Open
Abstract
Homozygous loss of SMN1 causes spinal muscular atrophy (SMA), the most common and devastating childhood genetic motor-neuron disease. The copy gene SMN2 produces only ∼10% functional SMN protein, insufficient to counteract development of SMA. In contrast, the human genetic modifier plastin 3 (PLS3), an actin-binding and -bundling protein, fully protects against SMA in SMN1-deleted individuals carrying 3-4 SMN2 copies. Here, we demonstrate that the combinatorial effect of suboptimal SMN antisense oligonucleotide treatment and PLS3 overexpression-a situation resembling the human condition in asymptomatic SMN1-deleted individuals-rescues survival (from 14 to >250 days) and motoric abilities in a severe SMA mouse model. Because PLS3 knockout in yeast impairs endocytosis, we hypothesized that disturbed endocytosis might be a key cellular mechanism underlying impaired neurotransmission and neuromuscular junction maintenance in SMA. Indeed, SMN deficit dramatically reduced endocytosis, which was restored to normal levels by PLS3 overexpression. Upon low-frequency electro-stimulation, endocytotic FM1-43 (SynaptoGreen) uptake in the presynaptic terminal of neuromuscular junctions was restored to control levels in SMA-PLS3 mice. Moreover, proteomics and biochemical analysis revealed CORO1C, another F-actin binding protein, whose direct binding to PLS3 is dependent on calcium. Similar to PLS3 overexpression, CORO1C overexpression restored fluid-phase endocytosis in SMN-knockdown cells by elevating F-actin amounts and rescued the axonal truncation and branching phenotype in Smn-depleted zebrafish. Our findings emphasize the power of genetic modifiers to unravel the cellular pathomechanisms underlying SMA and the power of combinatorial therapy based on splice correction of SMN2 and endocytosis improvement to efficiently treat SMA.
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Kreipke RE, Kwon YV, Shcherbata HR, Ruohola-Baker H. Drosophila melanogaster as a Model of Muscle Degeneration Disorders. Curr Top Dev Biol 2016; 121:83-109. [PMID: 28057309 DOI: 10.1016/bs.ctdb.2016.07.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Drosophila melanogaster provides a powerful platform with which researchers can dissect complex genetic questions and biochemical pathways relevant to a vast array of human diseases and disorders. Of particular interest, much work has been done with flies to elucidate the molecular mechanisms underlying muscle degeneration diseases. The fly is particularly useful for modeling muscle degeneration disorders because there are no identified satellite muscle cells to repair adult muscle following injury. This allows for the identification of endogenous processes of muscle degeneration as discrete events, distinguishable from phenotypes due to the lack of stem cell-based regeneration. In this review, we will discuss the ways in which the fruit fly provides a powerful platform with which to study human muscle degeneration disorders.
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Affiliation(s)
- R E Kreipke
- University of Washington, School of Medicine, Seattle, WA, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, School of Medicine, Seattle, WA, United States
| | - Y V Kwon
- University of Washington, School of Medicine, Seattle, WA, United States
| | - H R Shcherbata
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - H Ruohola-Baker
- University of Washington, School of Medicine, Seattle, WA, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, School of Medicine, Seattle, WA, United States.
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Garcia EL, Wen Y, Praveen K, Matera AG. Transcriptomic comparison of Drosophila snRNP biogenesis mutants reveals mutant-specific changes in pre-mRNA processing: implications for spinal muscular atrophy. RNA (NEW YORK, N.Y.) 2016; 22:1215-1227. [PMID: 27268418 PMCID: PMC4931114 DOI: 10.1261/rna.057208.116] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/12/2016] [Indexed: 06/06/2023]
Abstract
Survival motor neuron (SMN) functions in the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs) that catalyze pre-mRNA splicing. Here, we used disruptions in Smn and two additional snRNP biogenesis genes, Phax and Ars2, to classify RNA processing differences as snRNP-dependent or gene-specific in Drosophila Phax and Smn mutants exhibited comparable reductions in snRNAs, and comparison of their transcriptomes uncovered shared sets of RNA processing changes. In contrast, Ars2 mutants displayed only small decreases in snRNA levels, and RNA processing changes in these mutants were generally distinct from those identified in Phax and Smn animals. Instead, RNA processing changes in Ars2 mutants support the known interaction of Ars2 protein with the cap-binding complex, as splicing changes showed a clear bias toward the first intron. Bypassing disruptions in snRNP biogenesis, direct knockdown of spliceosomal proteins caused similar changes in the splicing of snRNP-dependent events. However, these snRNP-dependent events were largely unaltered in three Smn mutants expressing missense mutations that were originally identified in human spinal muscular atrophy (SMA) patients. Hence, findings here clarify the contributions of Phax, Smn, and Ars2 to snRNP biogenesis in Drosophila, and loss-of-function mutants for these proteins reveal differences that help disentangle cause and effect in SMA model flies.
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Affiliation(s)
- Eric L Garcia
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Ying Wen
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Kavita Praveen
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - A Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Poole AR, Enwerem II, Vicino IA, Coole JB, Smith SV, Hebert MD. Identification of processing elements and interactors implicate SMN, coilin and the pseudogene-encoded coilp1 in telomerase and box C/D scaRNP biogenesis. RNA Biol 2016; 13:955-972. [PMID: 27419845 DOI: 10.1080/15476286.2016.1211224] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Many cellular functions, such as translation, require ribonucleoproteins (RNPs). The biogenesis of RNPs is a multi-step process that, depending on the RNP, can take place in many cellular compartments. Here we examine 2 different RNPs: telomerase and small Cajal body-specific RNPs (scaRNPs). Both of these RNPs are enriched in the Cajal body (CB), which is a subnuclear domain that also has high concentrations of another RNP, small nuclear RNPs (snRNPs). SnRNPs are essential components of the spliceosome, and scaRNPs modify the snRNA component of the snRNP. The CB contains many proteins, including WRAP53, SMN and coilin, the CB marker protein. We show here that coilin, SMN and coilp1, a newly identified protein encoded by a pseudogene in human, associate with telomerase RNA and a subset of scaRNAs. We also have identified a processing element within box C/D scaRNA. Our findings thus further strengthen the connection between the CB proteins coilin and SMN in the biogenesis of telomeras e and box C/D scaRNPs, and reveal a new player, coilp1, that likely participates in this process.
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Affiliation(s)
- Aaron R Poole
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Isioma I Enwerem
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Ian A Vicino
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Jackson B Coole
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Stanley V Smith
- b Department of Pharmacology and Toxicology , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Michael D Hebert
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
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Genabai NK, Ahmad S, Zhang Z, Jiang X, Gabaldon CA, Gangwani L. Genetic inhibition of JNK3 ameliorates spinal muscular atrophy. Hum Mol Genet 2015; 24:6986-7004. [PMID: 26423457 DOI: 10.1093/hmg/ddv401] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/21/2015] [Indexed: 01/04/2023] Open
Abstract
Mutation of the Survival Motor Neuron 1 (SMN1) gene causes spinal muscular atrophy (SMA), an autosomal recessive neurodegenerative disorder that occurs in early childhood. Degeneration of spinal motor neurons caused by SMN deficiency results in progressive muscle atrophy and death in SMA. The molecular mechanism underlying neurodegeneration in SMA is unknown. No treatment is available to prevent neurodegeneration and reduce the burden of illness in SMA. We report that the c-Jun NH2-terminal kinase (JNK) signaling pathway mediates neurodegeneration in SMA. The neuron-specific isoform JNK3 is required for neuron degeneration caused by SMN deficiency. JNK3 deficiency reduces degeneration of cultured neurons caused by low levels of SMN. Genetic inhibition of JNK pathway in vivo by Jnk3 knockout results in amelioration of SMA phenotype. JNK3 deficiency prevents the loss of spinal cord motor neurons, reduces muscle degeneration, improves muscle fiber thickness and muscle growth, improves motor function and overall growth and increases lifespan of mice with SMA that shows a systemic rescue of phenotype by a SMN-independent mechanism. JNK3 represents a potential (non-SMN) therapeutic target for the treatment of SMA.
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Affiliation(s)
- Naresh K Genabai
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Saif Ahmad
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Zhanying Zhang
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Xiaoting Jiang
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Cynthia A Gabaldon
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Laxman Gangwani
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
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Gao X, Teng Y, Luo J, Huang L, Li M, Zhang Z, Ma YC, Ma L. The survival motor neuron gene smn-1 interacts with the U2AF large subunit gene uaf-1 to regulate Caenorhabditis elegans lifespan and motor functions. RNA Biol 2015; 11:1148-60. [PMID: 25483032 DOI: 10.4161/rna.36100] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Spinal muscular atrophy (SMA), the most frequent human congenital motor neuron degenerative disease, is caused by loss-of-function mutations in the highly conserved survival motor neuron gene SMN1. Mutations in SMN could affect several molecular processes, among which aberrant pre-mRNA splicing caused by defective snRNP biogenesis is hypothesized as a major cause of SMA. To date little is known about the interactions of SMN with other splicing factor genes and how SMN affects splicing in vivo. The nematode Caenorhabditis elegans carries a single ortholog of SMN, smn-1, and has been used as a model for studying the molecular functions of SMN. We analyzed RNA splicing of reporter genes in an smn-1 deletion mutant and found that smn-1 is required for efficient splicing at weak 3' splice sites. Genetic studies indicate that the defective lifespan and motor functions of the smn-1 deletion mutants could be significantly improved by mutations of the splicing factor U2AF large subunit gene uaf-1. In smn-1 mutants we detected a reduced expression of U1 and U5 snRNAs and an increased expression of U2, U4 and U6 snRNAs. Our study verifies an essential role of smn-1 for RNA splicing in vivo, identifies the uaf-1 gene as a potential genetic modifier of smn-1 mutants, and suggests that SMN-1 has multifaceted effects on the expression of spliceosomal snRNAs.
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Affiliation(s)
- Xiaoyang Gao
- a State Key Laboratory of Medical Genetics; School of Life Sciences ; Central South University ; Changsha , Hunan , China
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38
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Linder B, Fischer U, Gehring NH. mRNA metabolism and neuronal disease. FEBS Lett 2015; 589:1598-606. [DOI: 10.1016/j.febslet.2015.04.052] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/26/2015] [Accepted: 04/27/2015] [Indexed: 12/12/2022]
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Edens BM, Ajroud-Driss S, Ma L, Ma YC. Molecular mechanisms and animal models of spinal muscular atrophy. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1852:685-92. [PMID: 25088406 DOI: 10.1016/j.bbadis.2014.07.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/21/2014] [Accepted: 07/23/2014] [Indexed: 12/27/2022]
Abstract
Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, is characterized by the degeneration of spinal motor neurons and muscle atrophy. Although the genetic cause of SMA has been mapped to the Survival Motor Neuron1 (SMN1) gene, mechanisms underlying selective motor neuron degeneration in SMA remain largely unknown. Here we review the latest developments and our current understanding of the molecular mechanisms underlying SMA pathogenesis, focusing on the animal model systems that have been developed, as well as new diagnostic and treatment strategies that have been identified using these model systems. This article is part of a special issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis.
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Affiliation(s)
- Brittany M Edens
- Departments of Pediatrics, Neurology and Physiology, Northwestern University Feinberg School of Medicine, Lurie Children's Hospital of Chicago Research Center, IL 60611, Chicago
| | | | - Long Ma
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan 410078, China
| | - Yong-Chao Ma
- Departments of Pediatrics, Neurology and Physiology, Northwestern University Feinberg School of Medicine, Lurie Children's Hospital of Chicago Research Center, IL 60611, Chicago.
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Abstract
Pre-mRNA splicing is a critical step in eukaryotic gene expression that contributes to proteomic, cellular, and developmental complexity. Small nuclear (sn)RNAs are core spliceosomal components; however, the extent to which differential expression of snRNA isoforms regulates splicing is completely unknown. This is partly due to difficulties in the accurate analysis of the spatial and temporal expression patterns of snRNAs. Here, we use high-throughput RNA-sequencing (RNA-seq) data to profile expression of four major snRNAs throughout Drosophila development. This analysis shows that individual isoforms of each snRNA have distinct expression patterns in the embryo, larva, and pharate adult stages. Expression of these isoforms is more heterogeneous during embryogenesis; as development progresses, a single isoform from each snRNA subtype gradually dominates expression. Despite the lack of stable snRNA orthologous groups during evolution, this developmental switching of snRNA isoforms also occurs in distantly related vertebrate species, such as Xenopus, mouse, and human. Our results indicate that expression of snRNA isoforms is regulated and lays the foundation for functional studies of individual snRNA isoforms.
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Aghamaleky Sarvestany A, Hunter G, Tavendale A, Lamont DJ, Llavero Hurtado M, Graham LC, Wishart TM, Gillingwater TH. Label-free quantitative proteomic profiling identifies disruption of ubiquitin homeostasis as a key driver of Schwann cell defects in spinal muscular atrophy. J Proteome Res 2014; 13:4546-57. [PMID: 25151848 DOI: 10.1021/pr500492j] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Low levels of survival of motor neuron (SMN) protein cause the neuromuscular disease spinal muscular atrophy (SMA), characterized by degeneration of lower motor neurons and atrophy of skeletal muscle. Recent work demonstrated that low levels of SMN also trigger pathological changes in Schwann cells, leading to abnormal axon myelination and disrupted deposition of extracellular matrix proteins in peripheral nerve. However, the molecular pathways linking SMN depletion to intrinsic defects in Schwann cells remained unclear. Label-free proteomics analysis of Schwann cells isolated from SMA mouse peripheral nerve revealed widespread changes to the Schwann cell proteome, including disruption to growth/proliferation, cell death/survival, and molecular transport pathways. Functional clustering analyses revealed significant disruption to a number of proteins contributing to ubiquitination pathways, including reduced levels of ubiquitin-like modifier activating enzyme 1 (Uba1). Pharmacological suppression of Uba1 in Schwann cells was sufficient to reproduce the defective myelination phenotype seen in SMA. These findings demonstrate an important role for SMN protein and ubiquitin-dependent pathways in maintaining Schwann cell homeostasis and provide significant additional experimental evidence supporting a key role for ubiquitin pathways and, Uba1 in particular, in driving SMA pathogenesis across a broad range of cells and tissues.
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Affiliation(s)
- Arwin Aghamaleky Sarvestany
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh , Edinburgh EH8 9XD, United Kingdom
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Saal L, Briese M, Kneitz S, Glinka M, Sendtner M. Subcellular transcriptome alterations in a cell culture model of spinal muscular atrophy point to widespread defects in axonal growth and presynaptic differentiation. RNA (NEW YORK, N.Y.) 2014; 20:1789-802. [PMID: 25246652 PMCID: PMC4201830 DOI: 10.1261/rna.047373.114] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 08/22/2014] [Indexed: 05/19/2023]
Abstract
Neuronal function critically depends on coordinated subcellular distribution of mRNAs. Disturbed mRNA processing and axonal transport has been found in spinal muscular atrophy and could be causative for dysfunction and degeneration of motoneurons. Despite the advances made in characterizing the transport mechanisms of several axonal mRNAs, an unbiased approach to identify the axonal repertoire of mRNAs in healthy and degenerating motoneurons has been lacking. Here we used compartmentalized microfluidic chambers to investigate the somatodendritic and axonal mRNA content of cultured motoneurons by microarray analysis. In axons, transcripts related to protein synthesis and energy production were enriched relative to the somatodendritic compartment. Knockdown of Smn, the protein deficient in spinal muscular atrophy, produced a large number of transcript alterations in both compartments. Transcripts related to immune functions, including MHC class I genes, and with roles in RNA splicing were up-regulated in the somatodendritic compartment. On the axonal side, transcripts associated with axon growth and synaptic activity were down-regulated. These alterations provide evidence that subcellular localization of transcripts with axonal functions as well as regulation of specific transcripts with nonautonomous functions is disturbed in Smn-deficient motoneurons, most likely contributing to the pathophysiology of spinal muscular atrophy.
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Affiliation(s)
- Lena Saal
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
| | - Michael Briese
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
| | - Susanne Kneitz
- Department of Physiological Chemistry I, Biocenter, University of Wuerzburg, D 97074 Wuerzburg, Germany
| | - Michael Glinka
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
| | - Michael Sendtner
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
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Borg R, Cauchi RJ. GEMINs: potential therapeutic targets for spinal muscular atrophy? Front Neurosci 2014; 8:325. [PMID: 25360080 PMCID: PMC4197776 DOI: 10.3389/fnins.2014.00325] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/26/2014] [Indexed: 01/28/2023] Open
Abstract
The motor neuron degenerative disease spinal muscular atrophy (SMA) remains one of the most frequently inherited causes of infant mortality. Afflicted patients loose the survival motor neuron 1 (SMN1) gene but retain one or more copies of SMN2, a homolog that is incorrectly spliced. Primary treatment strategies for SMA aim at boosting SMN protein levels, which are insufficient in patients. SMN is known to partner with a set of diverse proteins collectively known as GEMINs to form a macromolecular complex. The SMN-GEMINs complex is indispensible for chaperoning the assembly of small nuclear ribonucleoproteins (snRNPs), which are key for pre-mRNA splicing. Pharmaceutics that alleviate the neuromuscular phenotype by restoring the fundamental function of SMN without augmenting its levels are also crucial in the development of an effective treatment. Their use as an adjunct therapy is predicted to enhance benefit to patients. Inspired by the surprising discovery revealing a premier role for GEMINs in snRNP biogenesis together with in vivo studies documenting their requirement for the correct function of the motor system, this review speculates on whether GEMINs constitute valid targets for SMA therapeutic development.
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Affiliation(s)
- Rebecca Borg
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta Msida, Malta
| | - Ruben J Cauchi
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta Msida, Malta
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Abstract
Spinal muscular atrophy (SMA) is a frequently fatal neuromuscular disorder and the most common inherited cause of infant mortality. SMA results from reduced levels of the survival of motor neuron (SMN) protein. Although the disease was first described more than a century ago, a precise understanding of its genetics was not obtained until the SMA genes were cloned in 1995. This was followed in rapid succession by experiments that assigned a role to the SMN protein in the proper splicing of genes, novel animal models of the disease, and the eventual use of the models in the pre clinical development of rational therapies for SMA. These successes have led the scientific and clinical communities to the cusp of what are expected to be the first truly promising treatments for the human disorder. Yet, important questions remain, not the least of which is how SMN paucity triggers a predominantly neuromuscular phenotype. Here we review how our understanding of the disease has evolved since the SMA genes were identified. We begin with a brief description of the genetics of SMA and the proposed roles of the SMN protein. We follow with an examination of how the genetics of the disease was exploited to develop genetically faithful animal models, and highlight the insights gained from their analysis. We end with a discussion of ongoing debates, future challenges, and the most promising treatments to have emerged from our current knowledge of the disease.
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Affiliation(s)
- Tomoyuki Awano
- />Department of Pathology and Cell Biology, Columbia University Medical Center, 630 W. 168th St., New York, NY 10032 USA
- />Center for Motor Neuron Biology and Disease, Columbia University Medical Center, 630 W. 168th St., New York, NY 10032 USA
| | - Jeong-Ki Kim
- />Department of Pathology and Cell Biology, Columbia University Medical Center, 630 W. 168th St., New York, NY 10032 USA
- />Center for Motor Neuron Biology and Disease, Columbia University Medical Center, 630 W. 168th St., New York, NY 10032 USA
| | - Umrao R. Monani
- />Department of Pathology and Cell Biology, Columbia University Medical Center, 630 W. 168th St., New York, NY 10032 USA
- />Center for Motor Neuron Biology and Disease, Columbia University Medical Center, 630 W. 168th St., New York, NY 10032 USA
- />Department of Neurology, Columbia University Medical Center, 630 W. 168th St., New York, NY 10032 USA
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SMA-causing missense mutations in survival motor neuron (Smn) display a wide range of phenotypes when modeled in Drosophila. PLoS Genet 2014; 10:e1004489. [PMID: 25144193 PMCID: PMC4140637 DOI: 10.1371/journal.pgen.1004489] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 05/19/2014] [Indexed: 11/30/2022] Open
Abstract
Mutations in the human survival motor neuron 1 (SMN) gene are the primary cause of spinal muscular atrophy (SMA), a devastating neuromuscular disorder. SMN protein has a well-characterized role in the biogenesis of small nuclear ribonucleoproteins (snRNPs), core components of the spliceosome. Additional tissue-specific and global functions have been ascribed to SMN; however, their relevance to SMA pathology is poorly understood and controversial. Using Drosophila as a model system, we created an allelic series of twelve Smn missense mutations, originally identified in human SMA patients. We show that animals expressing these SMA-causing mutations display a broad range of phenotypic severities, similar to the human disease. Furthermore, specific interactions with other proteins known to be important for SMN's role in RNP assembly are conserved. Intragenic complementation analyses revealed that the three most severe mutations, all of which map to the YG box self-oligomerization domain of SMN, display a stronger phenotype than the null allele and behave in a dominant fashion. In support of this finding, the severe YG box mutants are defective in self-interaction assays, yet maintain their ability to heterodimerize with wild-type SMN. When expressed at high levels, wild-type SMN is able to suppress the activity of the mutant protein. These results suggest that certain SMN mutants can sequester the wild-type protein into inactive complexes. Molecular modeling of the SMN YG box dimer provides a structural basis for this dominant phenotype. These data demonstrate that important structural and functional features of the SMN YG box are conserved between vertebrates and invertebrates, emphasizing the importance of self-interaction to the proper functioning of SMN. Spinal Muscular Atrophy (SMA) is a prevalent childhood neuromuscular disease, which in its most common form causes death by the age of two. One in fifty Americans is a carrier for SMA, making this genetic disease a serious health concern. SMA is caused by loss of function mutations in the survival motor neuron 1 (SMN1) gene. SMN is an essential protein and has a well-characterized function in the assembly of small nuclear ribonucleoproteins (snRNPs), which are core components of the spliceosome. To elucidate the phenotypic consequences of disrupting specific SMN protein interactions, we have generated a series of SMA-causing point mutations, modeled in Drosophila melanogaster. Using this system, we have shown that key aspects of SMN structure and function are conserved between humans and flies. Intragenic complementation analyses reveal the potential for dominant negative interactions between wild-type and mutant SMN subunits, highlighting the essential nature of the YG box in formation of higher-order SMN multimers. These results provide a basis for future studies investigating therapy targeted at restoration of functional SMN oligomers.
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Quality control of assembly-defective U1 snRNAs by decapping and 5'-to-3' exonucleolytic digestion. Proc Natl Acad Sci U S A 2014; 111:E3277-86. [PMID: 25071210 DOI: 10.1073/pnas.1412614111] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The accurate biogenesis of RNA-protein complexes is a key aspect of eukaryotic cells. Defects in Sm protein complex binding to snRNAs are known to reduce levels of snRNAs, suggesting an unknown quality control system for small nuclear ribonucleoprotein (snRNP) assembly. snRNA quality control may also be relevant in spinal muscular atrophy, which is caused by defects in the survival motor neuron (SMN)1 gene, an assembly factor for loading the Sm complex on snRNAs and, when severely reduced, can lead to reduced levels of snRNAs and splicing defects. To determine how assembly-defective snRNAs are degraded, we first demonstrate that yeast U1 Sm-mutant snRNAs are degraded either by Rrp6- or by Dcp2-dependent decapping/5'-to-3' decay. Knockdown of the decapping enzyme DCP2 in mammalian cells also increases the levels of assembly-defective snRNAs and suppresses some splicing defects seen in SMN-deficient cells. These results identify a conserved mechanism of snRNA quality control, and also suggest a general paradigm wherein the phenotype of an "RNP assembly disease" might be suppressed by inhibition of a competing RNA quality control mechanism.
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48
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Li DK, Tisdale S, Lotti F, Pellizzoni L. SMN control of RNP assembly: from post-transcriptional gene regulation to motor neuron disease. Semin Cell Dev Biol 2014; 32:22-9. [PMID: 24769255 DOI: 10.1016/j.semcdb.2014.04.026] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 04/17/2014] [Indexed: 11/25/2022]
Abstract
At the post-transcriptional level, expression of protein-coding genes is controlled by a series of RNA regulatory events including nuclear processing of primary transcripts, transport of mature mRNAs to specific cellular compartments, translation and ultimately, turnover. These processes are orchestrated through the dynamic association of mRNAs with RNA binding proteins and ribonucleoprotein (RNP) complexes. Accurate formation of RNPs in vivo is fundamentally important to cellular development and function, and its impairment often leads to human disease. The survival motor neuron (SMN) protein is key to this biological paradigm: SMN is essential for the biogenesis of various RNPs that function in mRNA processing, and genetic mutations leading to SMN deficiency cause the neurodegenerative disease spinal muscular atrophy. Here we review the expanding role of SMN in the regulation of gene expression through its multiple functions in RNP assembly. We discuss advances in our understanding of SMN activity as a chaperone of RNPs and how disruption of SMN-dependent RNA pathways can cause motor neuron disease.
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Affiliation(s)
- Darrick K Li
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Sarah Tisdale
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Francesco Lotti
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.
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49
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Wishart TM, Mutsaers CA, Riessland M, Reimer MM, Hunter G, Hannam ML, Eaton SL, Fuller HR, Roche SL, Somers E, Morse R, Young PJ, Lamont DJ, Hammerschmidt M, Joshi A, Hohenstein P, Morris GE, Parson SH, Skehel PA, Becker T, Robinson IM, Becker CG, Wirth B, Gillingwater TH. Dysregulation of ubiquitin homeostasis and β-catenin signaling promote spinal muscular atrophy. J Clin Invest 2014; 124:1821-34. [PMID: 24590288 PMCID: PMC3973095 DOI: 10.1172/jci71318] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 12/20/2013] [Indexed: 01/09/2023] Open
Abstract
The autosomal recessive neurodegenerative disease spinal muscular atrophy (SMA) results from low levels of survival motor neuron (SMN) protein; however, it is unclear how reduced SMN promotes SMA development. Here, we determined that ubiquitin-dependent pathways regulate neuromuscular pathology in SMA. Using mouse models of SMA, we observed widespread perturbations in ubiquitin homeostasis, including reduced levels of ubiquitin-like modifier activating enzyme 1 (UBA1). SMN physically interacted with UBA1 in neurons, and disruption of Uba1 mRNA splicing was observed in the spinal cords of SMA mice exhibiting disease symptoms. Pharmacological or genetic suppression of UBA1 was sufficient to recapitulate an SMA-like neuromuscular pathology in zebrafish, suggesting that UBA1 directly contributes to disease pathogenesis. Dysregulation of UBA1 and subsequent ubiquitination pathways led to β-catenin accumulation, and pharmacological inhibition of β-catenin robustly ameliorated neuromuscular pathology in zebrafish, Drosophila, and mouse models of SMA. UBA1-associated disruption of β-catenin was restricted to the neuromuscular system in SMA mice; therefore, pharmacological inhibition of β-catenin in these animals failed to prevent systemic pathology in peripheral tissues and organs, indicating fundamental molecular differences between neuromuscular and systemic SMA pathology. Our data indicate that SMA-associated reduction of UBA1 contributes to neuromuscular pathogenesis through disruption of ubiquitin homeostasis and subsequent β-catenin signaling, highlighting ubiquitin homeostasis and β-catenin as potential therapeutic targets for SMA.
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Affiliation(s)
- Thomas M. Wishart
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Chantal A. Mutsaers
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Markus Riessland
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Michell M. Reimer
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Gillian Hunter
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Marie L. Hannam
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Samantha L. Eaton
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Heidi R. Fuller
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Sarah L. Roche
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Eilidh Somers
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Robert Morse
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Philip J. Young
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Douglas J. Lamont
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Matthias Hammerschmidt
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Anagha Joshi
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Peter Hohenstein
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Glenn E. Morris
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Simon H. Parson
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Paul A. Skehel
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Thomas Becker
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Iain M. Robinson
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Catherina G. Becker
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Brunhilde Wirth
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Thomas H. Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom.
Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Human Genetics, Institute for Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom.
Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth), John Bull Building, Research Way, Tamar Science Park, Plymouth, United Kingdom.
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom, and Institute for Science and Technology in Medicine, Keele University, Keele, United Kingdom.
Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom.
Fingerprints Proteomics Facility, Dundee University, Dundee, United Kingdom.
Institute of Developmental Biology, University of Cologne, Cologne, Germany.
Division of Developmental Biology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Medical Sciences, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom
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Abstract
One of the most amazing findings in molecular biology was the discovery that eukaryotic genes are discontinuous, with coding DNA being interrupted by stretches of non-coding sequence. The subsequent realization that the intervening regions are removed from pre-mRNA transcripts via the activity of a common set of small nuclear RNAs (snRNAs), which assemble together with associated proteins into a complex known as the spliceosome, was equally surprising. How do cells coordinate the assembly of this molecular machine? And how does the spliceosome accurately recognize exons and introns to carry out the splicing reaction? Insights into these questions have been gained by studying the life cycle of spliceosomal snRNAs from their transcription, nuclear export and re-import to their dynamic assembly into the spliceosome. This assembly process can also affect the regulation of alternative splicing and has implications for human disease.
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Affiliation(s)
- A Gregory Matera
- Department of Biology, Department of Genetics and Integrative Program for Biological and Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Zefeng Wang
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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