1
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Wang L, Li P. Arginine methylation-enabled FUS phase separation with SMN contributes to neuronal granule formation. Cell Rep 2024; 43:114537. [PMID: 39052476 DOI: 10.1016/j.celrep.2024.114537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 05/03/2024] [Accepted: 07/09/2024] [Indexed: 07/27/2024] Open
Abstract
Various ribonucleoprotein complexes (RNPs) often function in the form of membraneless organelles derived from multivalence-driven liquid-liquid phase separation (LLPS). Post-translational modifications, such as phosphorylation and arginine methylation, govern the assembly and disassembly of membraneless organelles. This study reveals that asymmetric dimethylation of arginine can create extra binding sites for multivalent Tudor domain-containing proteins like survival of motor neuron (SMN) protein, thereby lowering the threshold for LLPS of RNPs, such as fused in sarcoma (FUS). Accordingly, FUS hypomethylation or knockdown of SMN disrupts the formation and transport of neuronal granules in axons. Wild-type SMN, but not the spinal muscular atrophy-associated form of SMN, SMN-Δ7, rescues neuronal defects due to SMN knockdown. Importantly, a fusion of SMN-Δ7 to an exogenous oligomeric protein is sufficient to rescue axon length defects caused by SMN knockdown. Our findings highlight the significant role of arginine methylation-enabled multivalent interactions in LLPS and suggest their potential impact on various aspects of neuronal activities in neurodegenerative diseases.
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Affiliation(s)
- Lingyao Wang
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University; Tsinghua-Peking Center for Life Sciences, Beijing 100084, China
| | - Pilong Li
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University; Tsinghua-Peking Center for Life Sciences, Beijing 100084, China.
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2
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Luo D, Ottesen EW, Lee JH, Singh RN. Transcriptome- and proteome-wide effects of a circular RNA encompassing four early exons of the spinal muscular atrophy genes. Sci Rep 2024; 14:10442. [PMID: 38714739 PMCID: PMC11076517 DOI: 10.1038/s41598-024-60593-7] [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: 12/28/2023] [Accepted: 04/25/2024] [Indexed: 05/10/2024] Open
Abstract
Spinal muscular atrophy (SMA) genes, SMN1 and SMN2 (hereinafter referred to as SMN1/2), produce multiple circular RNAs (circRNAs), including C2A-2B-3-4 that encompasses early exons 2A, 2B, 3 and 4. C2A-2B-3-4 is a universally and abundantly expressed circRNA of SMN1/2. Here we report the transcriptome- and proteome-wide effects of overexpression of C2A-2B-3-4 in inducible HEK293 cells. Our RNA-Seq analysis revealed altered expression of ~ 15% genes (4172 genes) by C2A-2B-3-4. About half of the affected genes by C2A-2B-3-4 remained unaffected by L2A-2B-3-4, a linear transcript encompassing exons 2A, 2B, 3 and 4 of SMN1/2. These findings underscore the unique role of the structural context of C2A-2B-3-4 in gene regulation. A surprisingly high number of upregulated genes by C2A-2B-3-4 were located on chromosomes 4 and 7, whereas many of the downregulated genes were located on chromosomes 10 and X. Supporting a cross-regulation of SMN1/2 transcripts, C2A-2B-3-4 and L2A-2B-3-4 upregulated and downregulated SMN1/2 mRNAs, respectively. Proteome analysis revealed 61 upregulated and 57 downregulated proteins by C2A-2B-3-4 with very limited overlap with those affected by L2A-2B-3-4. Independent validations confirmed the effect of C2A-2B-3-4 on expression of genes associated with chromatin remodeling, transcription, spliceosome function, ribosome biogenesis, lipid metabolism, cytoskeletal formation, cell proliferation and neuromuscular junction formation. Our findings reveal a broad role of C2A-2B-3-4, and expands our understanding of functions of SMN1/2 genes.
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Affiliation(s)
- Diou Luo
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - Eric W Ottesen
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - Ji Heon Lee
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA.
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3
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Luo D, Ottesen E, Lee JH, Singh R. Transcriptome- and proteome-wide effects of a circular RNA encompassing four early exons of the spinal muscular atrophy genes. RESEARCH SQUARE 2024:rs.3.rs-3818622. [PMID: 38464174 PMCID: PMC10925445 DOI: 10.21203/rs.3.rs-3818622/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Spinal muscular atrophy (SMA) genes, SMN1 and SMN2, produce multiple circular RNAs (circRNAs), including C2A-2B-3-4 that encompasses early exons 2A, 2B, 3 and 4. Here we report the transcriptome- and proteome-wide effects of overexpression of C2A-2B-3-4 in inducible HEK293 cells. Our RNA-Seq analysis revealed altered expression of ~ 15% genes (4,172 genes) by C2A-2B-3-4. About half of the affected genes by C2A-2B-3-4 remained unaffected by L2A-2B-3-4, a linear transcript encompassing exons 2A, 2B, 3 and 4 of SMN1/SMN2. These fifindings underscore the unique role of the structural context of C2A-2B-3-4 in gene regulation. A surprisingly high number of upregulated genes by C2A-2B-3-4 were located on chromosomes 4 and 7, whereas many of the downregulated genes were located on chromosomes 10 and X. Supporting a cross-regulation of SMN1/SMN2 transcripts, C2A-2B-3-4 and L2A-2B-3-4 upregulated and downregulated SMN1/SMN2 mRNAs, respectively. Proteome analysis revealed 61 upregulated and 57 downregulated proteins by C2A-2B-3-4 with very limited overlap with those affected by L2A-2B-3-4. Independent validations confirmed the effect of C2A-2B-3-4 on expression of genes associated with chromatin remodeling, transcription, spliceosome function, ribosome biogenesis, lipid metabolism, cytoskeletal formation, cell proliferation and neuromuscular junction formation. Our findings reveal a broad role of C2A-2B-3-4, a universally expressed circRNA produced by SMN1/SMN2.
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4
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Sharma G, Paganin M, Lauria F, Perenthaler E, Viero G. The SMN-ribosome interplay: a new opportunity for Spinal Muscular Atrophy therapies. Biochem Soc Trans 2024; 52:465-479. [PMID: 38391004 PMCID: PMC10903476 DOI: 10.1042/bst20231116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 02/24/2024]
Abstract
The underlying cause of Spinal Muscular Atrophy (SMA) is in the reduction of survival motor neuron (SMN) protein levels due to mutations in the SMN1 gene. The specific effects of SMN protein loss and the resulting pathological alterations are not fully understood. Given the crucial roles of the SMN protein in snRNP biogenesis and its interactions with ribosomes and translation-related proteins and mRNAs, a decrease in SMN levels below a specific threshold in SMA is expected to affect translational control of gene expression. This review covers both direct and indirect SMN interactions across various translation-related cellular compartments and processes, spanning from ribosome biogenesis to local translation and beyond. Additionally, it aims to outline deficiencies and alterations in translation observed in SMA models and patients, while also discussing the implications of the relationship between SMN protein and the translation machinery within the context of current and future therapies.
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5
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Kordala AJ, Stoodley J, Ahlskog N, Hanifi M, Garcia Guerra A, Bhomra A, Lim WF, Murray LM, Talbot K, Hammond SM, Wood MJA, Rinaldi C. PRMT inhibitor promotes SMN2 exon 7 inclusion and synergizes with nusinersen to rescue SMA mice. EMBO Mol Med 2023; 15:e17683. [PMID: 37724723 PMCID: PMC10630883 DOI: 10.15252/emmm.202317683] [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: 03/07/2023] [Revised: 08/31/2023] [Accepted: 09/01/2023] [Indexed: 09/21/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a leading genetic cause of infant mortality. The advent of approved treatments for this devastating condition has significantly changed SMA patients' life expectancy and quality of life. Nevertheless, these are not without limitations, and research efforts are underway to develop new approaches for improved and long-lasting benefits for patients. Protein arginine methyltransferases (PRMTs) are emerging as druggable epigenetic targets, with several small-molecule PRMT inhibitors already in clinical trials. From a screen of epigenetic molecules, we have identified MS023, a potent and selective type I PRMT inhibitor able to promote SMN2 exon 7 inclusion in preclinical SMA models. Treatment of SMA mice with MS023 results in amelioration of the disease phenotype, with strong synergistic amplification of the positive effect when delivered in combination with the antisense oligonucleotide nusinersen. Moreover, transcriptomic analysis revealed that MS023 treatment has minimal off-target effects, and the added benefit is mainly due to targeting neuroinflammation. Our study warrants further clinical investigation of PRMT inhibition both as a stand-alone and add-on therapy for SMA.
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Affiliation(s)
- Anna J Kordala
- Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
| | - Jessica Stoodley
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
| | - Nina Ahlskog
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
| | | | - Antonio Garcia Guerra
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
| | - Amarjit Bhomra
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
| | - Wooi Fang Lim
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
| | - Lyndsay M Murray
- Centre for Discovery Brain Sciences, College of Medicine and Veterinary MedicineUniversity of EdinburghEdinburghUK
- Euan McDonald Centre for Motor Neuron Disease ResearchUniversity of EdinburghEdinburghUK
| | - Kevin Talbot
- Nuffield Department of Clinical Neurosciences, John Radcliffe HospitalUniversity of OxfordOxfordUK
- Kavli Institute for Nanoscience DiscoveryUniversity of OxfordOxfordUK
| | | | - Matthew JA Wood
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
- MDUK Oxford Neuromuscular CentreOxfordUK
| | - Carlo Rinaldi
- Department of PaediatricsUniversity of OxfordOxfordUK
- Institute of Developmental and Regenerative Medicine (IDRM)OxfordUK
- MDUK Oxford Neuromuscular CentreOxfordUK
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6
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Wang J, Horlacher M, Cheng L, Winther O. RNA trafficking and subcellular localization-a review of mechanisms, experimental and predictive methodologies. Brief Bioinform 2023; 24:bbad249. [PMID: 37466130 PMCID: PMC10516376 DOI: 10.1093/bib/bbad249] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/30/2023] [Accepted: 06/16/2023] [Indexed: 07/20/2023] Open
Abstract
RNA localization is essential for regulating spatial translation, where RNAs are trafficked to their target locations via various biological mechanisms. In this review, we discuss RNA localization in the context of molecular mechanisms, experimental techniques and machine learning-based prediction tools. Three main types of molecular mechanisms that control the localization of RNA to distinct cellular compartments are reviewed, including directed transport, protection from mRNA degradation, as well as diffusion and local entrapment. Advances in experimental methods, both image and sequence based, provide substantial data resources, which allow for the design of powerful machine learning models to predict RNA localizations. We review the publicly available predictive tools to serve as a guide for users and inspire developers to build more effective prediction models. Finally, we provide an overview of multimodal learning, which may provide a new avenue for the prediction of RNA localization.
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Affiliation(s)
- Jun Wang
- Bioinformatics Centre, Department of Biology, University of Copenhagen, København Ø 2100, Denmark
| | - Marc Horlacher
- Computational Health Center, Helmholtz Center, Munich, Germany
| | - Lixin Cheng
- Shenzhen People’s Hospital, First Affiliated Hospital of Southern University of Science and Technology, Second Clinical Medicine College of Jinan University, Shenzhen 518020, China
| | - Ole Winther
- Bioinformatics Centre, Department of Biology, University of Copenhagen, København Ø 2100, Denmark
- Center for Genomic Medicine, Rigshospitalet (Copenhagen University Hospital), Copenhagen 2100, Denmark
- Section for Cognitive Systems, Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens Lyngby 2800, Denmark
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Nakevska Z, Yokota T. Challenges and future perspective of antisense therapy for spinal muscular atrophy: A review. Eur J Cell Biol 2023; 102:151326. [PMID: 37295266 DOI: 10.1016/j.ejcb.2023.151326] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 05/18/2023] [Accepted: 05/20/2023] [Indexed: 06/12/2023] Open
Abstract
Spinal muscular atrophy (SMA), the most common genetic cause of infantile death, is caused by a mutation in the survival of motor neuron 1 gene (SMN1), leading to the death of motor neurons and progressive muscle weakness. SMN1 normally produces an essential protein called SMN. Although humans possess a paralogous gene called SMN2, ∼90% of the SMN it produces is non-functional. This is due to a mutation in SMN2 that causes the skipping of a required exon during splicing of the pre-mRNA. The first treatment for SMA, nusinersen (brand name Spinraza), was approved by the FDA in 2016 and by the EMU in 2017. Nusinersen is an antisense oligonucleotide-based therapy that alters the splicing of SMN2 to make functional full-length SMN protein. Despite the recent advancements in antisense oligonucleotide therapy and SMA treatment development, nusinersen is faced with a multitude of challenges, such as intracellular and systemic delivery. In recent years, the use of peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs) in antisense therapy has gained interest. These are antisense oligonucleotides conjugated to cell-penetrating peptides such as Pips and DG9, and they have the potential to address the challenges associated with delivery. This review focuses on the historic milestones, development, current challenges, and future perspectives of antisense therapy for SMA.
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Affiliation(s)
- Zorica Nakevska
- Department of Biological Sciences, Faculty of Science, University of Alberta, 116 St. and 85 Ave., Edmonton AB T6G 2E1, Canada.
| | - Toshifumi Yokota
- Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, 116 St. and 85 Ave., Edmonton AB T6G 2E1, Canada; Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, 116 St. and 85 Ave., Edmonton AB T6G 2E1, Canada; The Friends of Garret Cumming Research and Muscular Dystrophy Canada HM Toupin Neurological Science Research Chair, 8812 112 St., Edmonton AB T6G 2H7, Canada.
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8
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He S, Valkov E, Cheloufi S, Murn J. The nexus between RNA-binding proteins and their effectors. Nat Rev Genet 2023; 24:276-294. [PMID: 36418462 DOI: 10.1038/s41576-022-00550-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2022] [Indexed: 11/25/2022]
Abstract
RNA-binding proteins (RBPs) regulate essentially every event in the lifetime of an RNA molecule, from its production to its destruction. Whereas much has been learned about RNA sequence specificity and general functions of individual RBPs, the ways in which numerous RBPs instruct a much smaller number of effector molecules, that is, the core engines of RNA processing, as to where, when and how to act remain largely speculative. Here, we survey the known modes of communication between RBPs and their effectors with a particular focus on converging RBP-effector interactions and their roles in reducing the complexity of RNA networks. We discern the emerging unifying principles and discuss their utility in our understanding of RBP function, regulation of biological processes and contribution to human disease.
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Affiliation(s)
- Shiyang He
- Department of Biochemistry, University of California, Riverside, CA, USA
- Center for RNA Biology and Medicine, Riverside, CA, USA
| | - Eugene Valkov
- RNA Biology Laboratory & Center for Structural Biology, Center for Cancer Research, National Cancer Institute (NCI), Frederick, MD, USA
| | - Sihem Cheloufi
- Department of Biochemistry, University of California, Riverside, CA, USA.
- Center for RNA Biology and Medicine, Riverside, CA, USA.
- Stem Cell Center, University of California, Riverside, CA, USA.
| | - Jernej Murn
- Department of Biochemistry, University of California, Riverside, CA, USA.
- Center for RNA Biology and Medicine, Riverside, CA, USA.
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Riboldi GM, Faravelli I, Rinchetti P, Lotti F. SMN post-translational modifications in spinal muscular atrophy. Front Cell Neurosci 2023; 17:1092488. [PMID: 36874214 PMCID: PMC9981653 DOI: 10.3389/fncel.2023.1092488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/26/2023] [Indexed: 02/19/2023] Open
Abstract
Since its first identification as the gene responsible for spinal muscular atrophy (SMA), the range of survival motor neuron (SMN) protein functions has increasingly expanded. This multimeric complex plays a crucial role in a variety of RNA processing pathways. While its most characterized function is in the biogenesis of ribonucleoproteins, several studies have highlighted the SMN complex as an important contributor to mRNA trafficking and translation, axonal transport, endocytosis, and mitochondria metabolism. All these multiple functions need to be selectively and finely modulated to maintain cellular homeostasis. SMN has distinct functional domains that play a crucial role in complex stability, function, and subcellular distribution. Many different processes were reported as modulators of the SMN complex activities, although their contribution to SMN biology still needs to be elucidated. Recent evidence has identified post-translational modifications (PTMs) as a way to regulate the pleiotropic functions of the SMN complex. These modifications include phosphorylation, methylation, ubiquitination, acetylation, sumoylation, and many other types. PTMs can broaden the range of protein functions by binding chemical moieties to specific amino acids, thus modulating several cellular processes. Here, we provide an overview of the main PTMs involved in the regulation of the SMN complex with a major focus on the functions that have been linked to SMA pathogenesis.
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Affiliation(s)
| | | | | | - Francesco Lotti
- Center for Motor Neuron Biology and Diseases, Departments of Pathology & Cell Biology, and Neurology, Columbia University Irving Medical Center, New York, NY, United States
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Faravelli I, Riboldi GM, Rinchetti P, Lotti F. The SMN Complex at the Crossroad between RNA Metabolism and Neurodegeneration. Int J Mol Sci 2023; 24:2247. [PMID: 36768569 PMCID: PMC9917330 DOI: 10.3390/ijms24032247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 01/17/2023] [Accepted: 01/20/2023] [Indexed: 01/24/2023] Open
Abstract
In the cell, RNA exists and functions in a complex with RNA binding proteins (RBPs) that regulate each step of the RNA life cycle from transcription to degradation. Central to this regulation is the role of several molecular chaperones that ensure the correct interactions between RNA and proteins, while aiding the biogenesis of large RNA-protein complexes (ribonucleoproteins or RNPs). Accurate formation of RNPs is fundamentally important to cellular development and function, and its impairment often leads to disease. The survival motor neuron (SMN) protein exemplifies this biological paradigm. SMN is part of a multi-protein complex essential for the biogenesis of various RNPs that function in RNA metabolism. Mutations leading to SMN deficiency cause the neurodegenerative disease spinal muscular atrophy (SMA). A fundamental question in SMA biology is how selective motor system dysfunction results from reduced levels of the ubiquitously expressed SMN protein. Recent clarification of the central role of the SMN complex in RNA metabolism and a thorough characterization of animal models of SMA have significantly advanced our knowledge of the molecular basis of the disease. Here we review the expanding role of SMN in the regulation of gene expression through its multiple functions in RNP biogenesis. We discuss developments in our understanding of SMN activity as a molecular chaperone of RNPs and how disruption of SMN-dependent RNA pathways can contribute to the SMA phenotype.
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Affiliation(s)
- Irene Faravelli
- Department of Stem Cell & Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
- Center for Motor Neuron Biology and Diseases, Departments of Pathology & Cell Biology, and Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Giulietta M. Riboldi
- Center for Motor Neuron Biology and Diseases, Departments of Pathology & Cell Biology, and Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
- The Marlene and Paolo Fresco Institute for Parkinson’s and Movement Disorders, NYU Langone Health, New York, NY 10017, USA
| | - Paola Rinchetti
- Center for Motor Neuron Biology and Diseases, Departments of Pathology & Cell Biology, and Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Francesco Lotti
- Center for Motor Neuron Biology and Diseases, Departments of Pathology & Cell Biology, and Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
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Zilio E, Piano V, Wirth B. Mitochondrial Dysfunction in Spinal Muscular Atrophy. Int J Mol Sci 2022; 23:ijms231810878. [PMID: 36142791 PMCID: PMC9503857 DOI: 10.3390/ijms231810878] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by recessive mutations in the SMN1 gene, globally affecting ~8-14 newborns per 100,000. The severity of the disease depends on the residual levels of functional survival of motor neuron protein, SMN. SMN is a ubiquitously expressed RNA binding protein involved in a plethora of cellular processes. In this review, we discuss the effects of SMN loss on mitochondrial functions in the neuronal and muscular systems that are the most affected in patients with spinal muscular atrophy. Our aim is to highlight how mitochondrial defects may contribute to disease progression and how restoring mitochondrial functionality may be a promising approach to develop new therapies. We also collected from previous studies a list of transcripts encoding mitochondrial proteins affected in various SMA models. Moreover, we speculate that in adulthood, when motor neurons require only very low SMN levels, the natural deterioration of mitochondria associated with aging may be a crucial triggering factor for adult spinal muscular atrophy, and this requires particular attention for therapeutic strategies.
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Affiliation(s)
- Eleonora Zilio
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
| | - Valentina Piano
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Correspondence: (V.P.); (B.W.)
| | - Brunhilde Wirth
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Correspondence: (V.P.); (B.W.)
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Brown SJ, Kline RA, Synowsky SA, Shirran SL, Holt I, Sillence KA, Claus P, Wirth B, Wishart TM, Fuller HR. The Proteome Signatures of Fibroblasts from Patients with Severe, Intermediate and Mild Spinal Muscular Atrophy Show Limited Overlap. Cells 2022; 11:cells11172624. [PMID: 36078032 PMCID: PMC9454632 DOI: 10.3390/cells11172624] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 12/04/2022] Open
Abstract
Most research to characterise the molecular consequences of spinal muscular atrophy (SMA) has focused on SMA I. Here, proteomic profiling of skin fibroblasts from severe (SMA I), intermediate (SMA II), and mild (SMA III) patients, alongside age-matched controls, was conducted using SWATH mass spectrometry analysis. Differentially expressed proteomic profiles showed limited overlap across each SMA type, and variability was greatest within SMA II fibroblasts, which was not explained by SMN2 copy number. Despite limited proteomic overlap, enriched canonical pathways common to two of three SMA severities with at least one differentially expressed protein from the third included mTOR signalling, regulation of eIF2 and eIF4 signalling, and protein ubiquitination. Network expression clustering analysis identified protein profiles that may discriminate or correlate with SMA severity. From these clusters, the differential expression of PYGB (SMA I), RAB3B (SMA II), and IMP1 and STAT1 (SMA III) was verified by Western blot. All SMA fibroblasts were transfected with an SMN-enhanced construct, but only RAB3B expression in SMA II fibroblasts demonstrated an SMN-dependent response. The diverse proteomic profiles and pathways identified here pave the way for studies to determine their utility as biomarkers for patient stratification or monitoring treatment efficacy and for the identification of severity-specific treatments.
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Affiliation(s)
- Sharon J. Brown
- School of Pharmacy and Bioengineering (PhaB), Keele University, Keele ST5 5BG, UK
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry SY10 7AG, UK
| | - Rachel A. Kline
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, UK
- Euan MacDonald Centre, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Silvia A. Synowsky
- BSRC Mass Spectrometry and Proteomics Facility, University of St Andrews, St Andrews KY16 9ST, UK
| | - Sally L. Shirran
- BSRC Mass Spectrometry and Proteomics Facility, University of St Andrews, St Andrews KY16 9ST, UK
| | - Ian Holt
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry SY10 7AG, UK
| | | | - Peter Claus
- SMATHERIA gGmbH—Non-Profit Biomedical Research Institute, 30625 Hannover, Germany
| | - Brunhilde Wirth
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
- Institute for Genetics, University of Cologne, 50931 Cologne, Germany
| | - Thomas M. Wishart
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, UK
- Euan MacDonald Centre, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Heidi R. Fuller
- School of Pharmacy and Bioengineering (PhaB), Keele University, Keele ST5 5BG, UK
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry SY10 7AG, UK
- Correspondence: ; Tel.: +44-(0)1-782-734546
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13
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Ravel-Chapuis A, Haghandish A, Daneshvar N, Jasmin BJ, Côté J. A novel CARM1-HuR axis involved in muscle differentiation and plasticity misregulated in spinal muscular atrophy. Hum Mol Genet 2021; 31:1453-1470. [PMID: 34791230 DOI: 10.1093/hmg/ddab333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/19/2021] [Accepted: 10/19/2021] [Indexed: 11/14/2022] Open
Abstract
Spinal muscular atrophy (SMA) is characterized by the loss of alpha motor neurons in the spinal cord and a progressive muscle weakness and atrophy. SMA is caused by loss-of-function mutations and/or deletions in the survival of motor neuron (SMN) gene. The role of SMN in motor neurons has been extensively studied, but its function and the consequences of its loss in muscle has also emerged as a key aspect of SMA pathology. In this study, we explore the molecular mechanisms involved in muscle defects in SMA. First, we show in C2C12 myoblasts, that arginine methylation by CARM1 controls myogenic differentiation. More specifically, the methylation of HuR on K217 regulates HuR levels and subcellular localization during myogenic differentiation, and the formation of myotubes. Furthermore, we demonstrate that SMN and HuR interact in C2C12 myoblasts. Interestingly, the SMA-causing E134K point mutation within the SMN Tudor domain, and CARM1 depletion, modulate the SMN-HuR interaction. In addition, using the Smn2B/- mouse model, we report that CARM1 levels are markedly increased in SMA muscles and that HuR fails to properly respond to muscle denervation, thereby affecting the regulation of its mRNA targets. Altogether, our results show a novel CARM1-HuR axis in the regulation of muscle differentiation and plasticity as well as in the aberrant regulation of this axis caused by the absence of SMN in SMA muscle. With the recent developments of therapeutics targeting motor neurons, this study further indicates the need for more global therapeutic approaches for SMA.
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Affiliation(s)
- Aymeric Ravel-Chapuis
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Eric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Amir Haghandish
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Eric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Nasibeh Daneshvar
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Eric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Bernard J Jasmin
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Eric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Jocelyn Côté
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Eric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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14
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Koh A, Sarusie MV, Ohmer J, Fischer U, Winkler C, Wohland T. Fluorescence Correlation Spectroscopy Reveals Survival Motor Neuron Oligomerization but No Active Transport in Motor Axons of a Zebrafish Model for Spinal Muscular Atrophy. Front Cell Dev Biol 2021; 9:639904. [PMID: 34458251 PMCID: PMC8385639 DOI: 10.3389/fcell.2021.639904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 07/23/2021] [Indexed: 11/13/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is a progressive neurodegenerative disease affecting lower motor neurons that is caused by a deficiency in ubiquitously expressed Survival Motor Neuron (SMN) protein. Two mutually exclusive hypotheses have been discussed to explain increased motor neuron vulnerability in SMA. Reduced SMN levels have been proposed to lead to defective snRNP assembly and aberrant splicing of transcripts that are essential for motor neuron maintenance. An alternative hypothesis proposes a motor neuron-specific function for SMN in axonal transport of mRNAs and/or RNPs. To address these possibilities, we used a novel in vivo approach with fluorescence correlation spectroscopy (FCS) in transgenic zebrafish embryos to assess the subcellular dynamics of Smn in motor neuron cell bodies and axons. Using fluorescently tagged Smn we show that it exists as two freely diffusing components, a monomeric, and a complex-bound, likely oligomeric, component. This oligomer hypothesis was supported by the disappearance of the complex-bound form for a truncated Smn variant that is deficient in oligomerization and a change in its dynamics under endogenous Smn deficient conditions. Surprisingly, our FCS measurements did not provide any evidence for an active transport of Smn in axons. Instead, our in vivo observations are consistent with previous findings that SMN acts as a chaperone for the assembly of snRNP and mRNP complexes.
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Affiliation(s)
- Angela Koh
- Department of Biological Sciences, Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Menachem Viktor Sarusie
- Department of Biological Sciences, Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Jürgen Ohmer
- Department of Biochemistry, Theodor-Boveri-Institut für Biowissenschaften (Biozentrum), University of Wuerzburg, Wuerzburg, Germany
| | - Utz Fischer
- Department of Biochemistry, Theodor-Boveri-Institut für Biowissenschaften (Biozentrum), University of Wuerzburg, Wuerzburg, Germany
| | - Christoph Winkler
- Department of Biological Sciences, Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences, Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore.,Department of Chemistry, National University of Singapore, Singapore, Singapore
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15
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Blatnik AJ, McGovern VL, Burghes AHM. What Genetics Has Told Us and How It Can Inform Future Experiments for Spinal Muscular Atrophy, a Perspective. Int J Mol Sci 2021; 22:8494. [PMID: 34445199 PMCID: PMC8395208 DOI: 10.3390/ijms22168494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/28/2021] [Accepted: 08/04/2021] [Indexed: 02/06/2023] Open
Abstract
Proximal spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disorder characterized by motor neuron loss and subsequent atrophy of skeletal muscle. SMA is caused by deficiency of the essential survival motor neuron (SMN) protein, canonically responsible for the assembly of the spliceosomal small nuclear ribonucleoproteins (snRNPs). Therapeutics aimed at increasing SMN protein levels are efficacious in treating SMA. However, it remains unknown how deficiency of SMN results in motor neuron loss, resulting in many reported cellular functions of SMN and pathways affected in SMA. Herein is a perspective detailing what genetics and biochemistry have told us about SMA and SMN, from identifying the SMA determinant region of the genome, to the development of therapeutics. Furthermore, we will discuss how genetics and biochemistry have been used to understand SMN function and how we can determine which of these are critical to SMA moving forward.
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Affiliation(s)
| | | | - Arthur H. M. Burghes
- Department of Biological Chemistry & Pharmacology, The Ohio State University Wexner Medical Center, Rightmire Hall, Room 168, 1060 Carmack Road, Columbus, OH 43210, USA; (A.J.B.III); (V.L.M.)
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16
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Gamarra M, de la Cruz A, Blanco-Urrejola M, Baleriola J. Local Translation in Nervous System Pathologies. Front Integr Neurosci 2021; 15:689208. [PMID: 34276318 PMCID: PMC8279726 DOI: 10.3389/fnint.2021.689208] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/03/2021] [Indexed: 12/13/2022] Open
Abstract
Dendrites and axons can extend dozens to hundreds of centimeters away from the cell body so that a single neuron can sense and respond to thousands of stimuli. Thus, for an accurate function of dendrites and axons the neuronal proteome needs to be asymmetrically distributed within neurons. Protein asymmetry can be achieved by the transport of the protein itself or the transport of the mRNA that is then translated at target sites in neuronal processes. The latter transport mechanism implies local translation of localized mRNAs. The role of local translation in nervous system (NS) development and maintenance is well established, but recently there is growing evidence that this mechanism and its deregulation are also relevant in NS pathologies, including neurodegenerative diseases. For instance, upon pathological signals disease-related proteins can be locally synthesized in dendrites and axons. Locally synthesized proteins can exert their effects at or close to the site of translation, or they can be delivered to distal compartments like the nucleus and induce transcriptional responses that lead to neurodegeneration, nerve regeneration and other cell-wide responses. Relevant key players in the process of local protein synthesis are RNA binding proteins (RBPs), responsible for mRNA transport to neurites. Several neurological and neurodegenerative disorders, including amyotrophic lateral sclerosis or spinal motor atrophy, are characterized by mutations in genes encoding for RBPs and consequently mRNA localization and local translation are impaired. In other diseases changes in the local mRNA repertoire and altered local protein synthesis have been reported. In this review, we will discuss how deregulation of localized translation at different levels can contribute to the development and progression of nervous system pathologies.
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Affiliation(s)
- María Gamarra
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Neurociencias, Universidad del País Vasco (UPV/EHU), Leioa, Spain
| | - Aida de la Cruz
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Neurociencias, Universidad del País Vasco (UPV/EHU), Leioa, Spain
| | - Maite Blanco-Urrejola
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Neurociencias, Universidad del País Vasco (UPV/EHU), Leioa, Spain.,Departamento de Biología Celular e Histología, Universidad del País Vasco (UPV/EHU), Leioa, Spain
| | - Jimena Baleriola
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Biología Celular e Histología, Universidad del País Vasco (UPV/EHU), Leioa, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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17
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Gandhi G, Abdullah S, Foead AI, Yeo WWY. The potential role of miRNA therapies in spinal muscle atrophy. J Neurol Sci 2021; 427:117485. [PMID: 34015517 DOI: 10.1016/j.jns.2021.117485] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/14/2021] [Accepted: 05/10/2021] [Indexed: 01/15/2023]
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by low levels of full-length survival motor neuron (SMN) protein due to the loss of the survival motor neuron 1 (SMN1) gene and inefficient splicing of the survival motor neuron 2 (SMN2) gene, which mostly affects alpha motor neurons of the lower spinal cord. Despite the U.S. Food and Drug Administration (FDA) approved SMN-dependent therapies including Nusinersen, Zolgensma® and Evrysdi™, SMA is still a devastating disease as these existing expensive drugs may not be sufficient and thus, remains a need for additional therapies. The involvement of microRNAs (miRNAs) in SMA is expanding because miRNAs are important mediators of gene expression as each miRNA could target a number of genes. Hence, miRNA-based therapy could be utilized in treating this genetic disorder. However, the delivery of miRNAs into the target cells remains an obstacle in SMA, as there is no effective delivery system to date. This review highlights the potential strategies for intracellular miRNA delivery into target cells and current challenges in miRNA delivery. Furthermore, we provide the future prospects of miRNA-based therapeutic strategies in SMA.
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Affiliation(s)
- Gayatri Gandhi
- Perdana University Graduate School of Medicine, Perdana University, Wisma Chase Perdana, Changkat Semantan, Damansara Heights, 50490 Kuala Lumpur, Malaysia
| | - Syahril Abdullah
- Medical Genetics Laboratory, Department of Biomedical Sciences, Faculty of Medicine & Health Sciences, Universiti Putra Malaysia, 43400 UPM, Selangor, Malaysia; Genetics & Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Selangor, Malaysia; UPM-MAKNA Cancer Research Laboratory, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Selangor, Malaysia
| | - Agus Iwan Foead
- Department of Orthopedics, Perdana University-Royal College of Surgeons in Ireland, Perdana University, Wisma Chase Perdana, Changkat Semantan, Damansara Heights, 50490 Kuala Lumpur, Malaysia
| | - Wendy Wai Yeng Yeo
- Perdana University Graduate School of Medicine, Perdana University, Wisma Chase Perdana, Changkat Semantan, Damansara Heights, 50490 Kuala Lumpur, Malaysia.
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18
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Perrone-Capano C, Volpicelli F, Penna E, Chun JT, Crispino M. Presynaptic protein synthesis and brain plasticity: From physiology to neuropathology. Prog Neurobiol 2021; 202:102051. [PMID: 33845165 DOI: 10.1016/j.pneurobio.2021.102051] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 03/14/2021] [Accepted: 04/07/2021] [Indexed: 12/12/2022]
Abstract
To form and maintain extremely intricate and functional neural circuitry, mammalian neurons are typically endowed with highly arborized dendrites and a long axon. The synapses that link neurons to neurons or to other cells are numerous and often too remote for the cell body to make and deliver new proteins to the right place in time. Moreover, synapses undergo continuous activity-dependent changes in their number and strength, establishing the basis of neural plasticity. The innate dilemma is then how a highly complex neuron provides new proteins for its cytoplasmic periphery and individual synapses to support synaptic plasticity. Here, we review a growing body of evidence that local protein synthesis in discrete sites of the axon and presynaptic terminals plays crucial roles in synaptic plasticity, and that deregulation of this local translation system is implicated in various pathologies of the nervous system.
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Affiliation(s)
- Carla Perrone-Capano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy; Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, Italy.
| | | | - Eduardo Penna
- Department of Biology, University of Naples Federico II, Naples, Italy.
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy.
| | - Marianna Crispino
- Department of Biology, University of Naples Federico II, Naples, Italy.
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19
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Gollapalli K, Kim JK, Monani UR. Emerging concepts underlying selective neuromuscular dysfunction in infantile-onset spinal muscular atrophy. Neural Regen Res 2021; 16:1978-1984. [PMID: 33642371 PMCID: PMC8343306 DOI: 10.4103/1673-5374.308073] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Infantile-onset spinal muscular atrophy is the quintessential example of a disorder characterized by a predominantly neurodegenerative phenotype that nevertheless stems from perturbations in a housekeeping protein. Resulting from low levels of the Survival of Motor Neuron (SMN) protein, spinal muscular atrophy manifests mainly as a lower motor neuron disease. Why this is so and whether other cell types contribute to the classic spinal muscular atrophy phenotype continue to be the subject of intense investigation and are only now gaining appreciation. Yet, what is emerging is sometimes as puzzling as it is instructive, arguing for a careful re-examination of recent study outcomes, raising questions about established dogma in the field and making the case for a greater focus on milder spinal muscular atrophy models as tools to identify key mechanisms driving selective neuromuscular dysfunction in the disease. This review examines the evidence for novel molecular and cellular mechanisms that have recently been implicated in spinal muscular atrophy, highlights breakthroughs, points out caveats and poses questions that ought to serve as the basis of new investigations to better understand and treat this and other more common neurodegenerative disorders.
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Affiliation(s)
- Kishore Gollapalli
- Department of Neurology; Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, NY, USA
| | - Jeong-Ki Kim
- Department of Neurology; Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, NY, USA
| | - Umrao R Monani
- Department of Neurology; Department of Pathology & Cell Biology; Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, NY, USA
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20
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Chen TH. Circulating microRNAs as potential biomarkers and therapeutic targets in spinal muscular atrophy. Ther Adv Neurol Disord 2020; 13:1756286420979954. [PMID: 33488772 PMCID: PMC7768327 DOI: 10.1177/1756286420979954] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 11/20/2020] [Indexed: 12/12/2022] Open
Abstract
Spinal muscular atrophy (SMA), a leading genetic cause of infant death, is a neurodegenerative disease characterized by the selective loss of particular groups of motor neurons (MNs) in the anterior horn of the spinal cord with progressive muscle wasting. SMA is caused by a deficiency of the survival motor neuron (SMN) protein due to a homozygous deletion or mutation of the SMN1 gene. However, the molecular mechanisms whereby the SMN complex regulates MN functions are not fully elucidated. Emerging studies on SMA pathogenesis have turned the attention of researchers to RNA metabolism, given that increasingly identified SMN-associated modifiers are involved in both coding and non-coding RNA (ncRNA) processing. Among various ncRNAs, microRNAs (miRNAs) are the most studied in terms of regulation of posttranscriptional gene expression. Recently, the discovery that miRNAs are critical to MN function and survival led to the study of dysregulated miRNAs in SMA pathogenesis. Circulating miRNAs have drawn attention as a readily available biomarker due to their property of being clinically detectable in numerous human biofluids through non-invasive approaches. As there are recent promising findings from novel miRNA-based medicines, this article presents an extensive review of the most up-to-date studies connecting specific miRNAs to SMA pathogenesis and the potential applications of miRNAs as biomarkers and therapeutic targets for SMA.
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Affiliation(s)
- Tai-Heng Chen
- Department of Pediatrics, Division of Pediatric Emergency, Kaohsiung Medical University Hospital, School of Post-Baccalaureate Medicine, College of Medicine, Kaohsiung Medical University, No. 100, Tzyou 1st Road, Kaohsiung 80708, Taiwan
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21
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Ottesen EW, Singh RN. Characteristics of circular RNAs generated by human Survival Motor Neuron genes. Cell Signal 2020; 73:109696. [PMID: 32553550 PMCID: PMC7387165 DOI: 10.1016/j.cellsig.2020.109696] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023]
Abstract
Circular RNAs (circRNAs) belong to a diverse class of stable RNAs expressed in all cell types. Their proposed functions include sponging of microRNAs (miRNAs), sequestration and trafficking of proteins, assembly of multimeric complexes, production of peptides, and regulation of transcription. Backsplicing due to RNA structures formed by an exceptionally high number of Alu repeats lead to the production of a vast repertoire of circRNAs by human Survival Motor Neuron genes, SMN1 and SMN2, that code for SMN, an essential multifunctional protein. Low levels of SMN due to deletion or mutation of SMN1 result in spinal muscular atrophy (SMA), a major genetic disease of infants and children. Mild SMA is also recorded in adult population, expanding the spectrum of the disease. Here we review SMN circRNAs with respect to their biogenesis, sequence features, and potential functions. We also discuss how SMN circRNAs could be exploited for diagnostic and therapeutic purposes.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America.
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22
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Abstract
RNA-binding proteins are a critical group of multifunctional proteins that precisely regulate all aspects of gene expression, from alternative splicing to mRNA trafficking, stability, and translation. Converging evidence highlights aberrant RNA metabolism as a common pathogenic mechanism in several neurodevelopmental and neurodegenerative diseases. However, dysregulation of disease-linked RNA-binding proteins results in widespread, often tissue-specific and/or pleiotropic effects on the transcriptome, making it challenging to determine the underlying cellular and molecular mechanisms that contribute to disease pathogenesis. Understanding how splicing misregulation as well as alterations of mRNA stability and localization impact the activity and function of neuronal proteins is fundamental to addressing neurodevelopmental defects and synaptic dysfunction in disease. Here we highlight recent exciting studies that use high-throughput transcriptomic analysis and advanced genetic, cell biological, and imaging approaches to dissect the role of disease-linked RNA-binding proteins on different RNA processing steps. We focus specifically on efforts to elucidate the functional consequences of aberrant RNA processing on neuronal morphology, synaptic activity and plasticity in development and disease. We also consider new areas of investigation that will elucidate the molecular mechanisms RNA-binding proteins use to achieve spatiotemporal control of gene expression for neuronal homeostasis and plasticity.
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Affiliation(s)
- Shavanie Prashad
- Department of Pathology, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Experimental Pathology Graduate Group, Yale University School of Medicine, Yale University, New Haven, CT, USA
| | - Pallavi P Gopal
- Department of Pathology, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Experimental Pathology Graduate Group, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Yale Center for RNA Science and Medicine, Yale University School of Medicine, Yale University, New Haven, CT, USA
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23
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Glial cells involvement in spinal muscular atrophy: Could SMA be a neuroinflammatory disease? Neurobiol Dis 2020; 140:104870. [PMID: 32294521 DOI: 10.1016/j.nbd.2020.104870] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/16/2020] [Accepted: 04/10/2020] [Indexed: 01/11/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a severe, inherited disease characterized by the progressive degeneration and death of motor neurons of the anterior horns of the spinal cord, which results in muscular atrophy and weakness of variable severity. Its early-onset form is invariably fatal in early childhood, while milder forms lead to permanent disability, physical deformities and respiratory complications. Recently, two novel revolutionary therapies, antisense oligonucleotides and gene therapy, have been approved, and might prove successful in making long-term survival of these patients likely. In this perspective, a deep understanding of the pathogenic mechanisms and of their impact on the interactions between motor neurons and other cell types within the central nervous system (CNS) is crucial. Studies using SMA animal and cellular models have taught us that the survival and functionality of motor neurons is highly dependent on a whole range of other cell types, namely glial cells, which are responsible for a variety of different functions, such as neuronal trophic support, synaptic remodeling, and immune surveillance. Thus, it emerges that SMA is likely a non-cell autonomous, multifactorial disease in which the interaction of different cell types and disease mechanisms leads to motor neurons failure and loss. This review will introduce the different glial cell types in the CNS and provide an overview of the role of glial cells in motor neuron degeneration in SMA. Furthermore, we will discuss the relevance of these findings so far and the potential impact on the success of available therapies and on the development of novel ones.
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24
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Chaudhuri A, Das S, Das B. Localization elements and zip codes in the intracellular transport and localization of messenger RNAs in Saccharomyces cerevisiae. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1591. [PMID: 32101377 DOI: 10.1002/wrna.1591] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/05/2020] [Accepted: 02/07/2020] [Indexed: 12/13/2022]
Abstract
Intracellular trafficking and localization of mRNAs provide a mechanism of regulation of expression of genes with excellent spatial control. mRNA localization followed by localized translation appears to be a mechanism of targeted protein sorting to a specific cell-compartment, which is linked to the establishment of cell polarity, cell asymmetry, embryonic axis determination, and neuronal plasticity in metazoans. However, the complexity of the mechanism and the components of mRNA localization in higher organisms prompted the use of the unicellular organism Saccharomyces cerevisiae as a simplified model organism to study this vital process. Current knowledge indicates that a variety of mRNAs are asymmetrically and selectively localized to the tip of the bud of the daughter cells, to the vicinity of endoplasmic reticulum, mitochondria, and nucleus in this organism, which are connected to diverse cellular processes. Interestingly, specific cis-acting RNA localization elements (LEs) or RNA zip codes play a crucial role in the localization and trafficking of these localized mRNAs by providing critical binding sites for the specific RNA-binding proteins (RBPs). In this review, we present a comprehensive account of mRNA localization in S. cerevisiae, various types of localization elements influencing the mRNA localization, and the RBPs, which bind to these LEs to implement a number of vital physiological processes. Finally, we emphasize the significance of this process by highlighting their connection to several neuropathological disorders and cancers. This article is categorized under: RNA Export and Localization > RNA Localization.
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Affiliation(s)
- Anusha Chaudhuri
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
| | - Subhadeep Das
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
| | - Biswadip Das
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
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25
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Thelen MP, Kye MJ. The Role of RNA Binding Proteins for Local mRNA Translation: Implications in Neurological Disorders. Front Mol Biosci 2020; 6:161. [PMID: 32010708 PMCID: PMC6974540 DOI: 10.3389/fmolb.2019.00161] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 12/20/2019] [Indexed: 12/11/2022] Open
Abstract
As neurons are one of the most highly polarized cells in our body, they require sophisticated cellular mechanisms to maintain protein homeostasis in their subcellular compartments such as axons and dendrites. When neuronal protein homeostasis is disturbed due to genetic mutations or deletions, this often results in degeneration of neurons leading to devastating outcome such as spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), and fragile X syndrome (FXS). Ribonucleoprotein (RNP) complexes are macromolecular complexes composed of RNA binding proteins (RBPs) and their target RNAs. RBPs contain RNA binding domains and bind to RNA molecules via specific sequence motifs. RNP complexes have various functions in gene expression including messenger RNA (mRNA) trafficking, RNA processing and silencing. In neurons, RBPs deliver specific sets of mRNAs to subcellular compartments such as axons and dendrites to be locally translated. Mutations or deletions in genes coding for RNPs have been reported as causes for neurological disorders such as SMA, ALS, and FXS. As RBPs determine axonal or dendritic mRNA repertoires as well as proteomes by trafficking selective mRNAs and regulating local protein synthesis, they play a crucial role for neuronal function. In this review, we summarize the role of well-known RBPs, SMN, TDP-43, FUS, and FMRP, and review their function for local protein synthesis in neurons. Furthermore, we discuss their pathological contribution to the neurological disorders.
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Affiliation(s)
| | - Min Jeong Kye
- Institute of Human Genetics, University of Cologne, Cologne, Germany
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26
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Pushpalatha KV, Besse F. Local Translation in Axons: When Membraneless RNP Granules Meet Membrane-Bound Organelles. Front Mol Biosci 2019; 6:129. [PMID: 31824961 PMCID: PMC6882739 DOI: 10.3389/fmolb.2019.00129] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 11/06/2019] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic cell compartmentalization relies on long-known membrane-delimited organelles, as well as on more recently discovered membraneless macromolecular condensates. How these two types of organelles interact to regulate cellular functions is still largely unclear. In this review, we highlight how membraneless ribonucleoprotein (RNP) organelles, enriched in RNAs and associated regulatory proteins, cooperate with membrane-bound organelles for tight spatio-temporal control of gene expression in the axons of neuronal cells. Specifically, we present recent evidence that motile membrane-bound organelles are used as vehicles by RNP cargoes, promoting the long-range transport of mRNA molecules to distal axons. As demonstrated by recent work, membrane-bound organelles also promote local protein synthesis, by serving as platforms for the local translation of mRNAs recruited to their outer surface. Furthermore, dynamic and specific association between RNP cargoes and membrane-bound organelles is mediated by bi-partite adapter molecules that interact with both types of organelles selectively, in a regulated-manner. Maintaining such a dynamic interplay is critical, as alterations in this process are linked to neurodegenerative diseases. Together, emerging studies thus point to the coordination of membrane-bound and membraneless organelles as an organizing principle underlying local cellular responses.
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Affiliation(s)
| | - Florence Besse
- Université Côte d'Azur, CNRS, Inserm, Institut de Biology Valrose, Nice, France
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27
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Chen TH, Chen JA. Multifaceted roles of microRNAs: From motor neuron generation in embryos to degeneration in spinal muscular atrophy. eLife 2019; 8:50848. [PMID: 31738166 PMCID: PMC6861003 DOI: 10.7554/elife.50848] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/05/2019] [Indexed: 12/12/2022] Open
Abstract
Two crucial questions in neuroscience are how neurons establish individual identity in the developing nervous system and why only specific neuron subtypes are vulnerable to neurodegenerative diseases. In the central nervous system, spinal motor neurons serve as one of the best-characterized cell types for addressing these two questions. In this review, we dissect these questions by evaluating the emerging role of regulatory microRNAs in motor neuron generation in developing embryos and their potential contributions to neurodegenerative diseases such as spinal muscular atrophy (SMA). Given recent promising results from novel microRNA-based medicines, we discuss the potential applications of microRNAs for clinical assessments of SMA disease progression and treatment.
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Affiliation(s)
- Tai-Heng Chen
- PhD Program in Translational Medicine, Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Academia Sinica, Kaohsiung, Taiwan.,Department of Pediatrics, Division of Pediatric Emergency, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Jun-An Chen
- PhD Program in Translational Medicine, Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Academia Sinica, Kaohsiung, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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28
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Formicola N, Vijayakumar J, Besse F. Neuronal ribonucleoprotein granules: Dynamic sensors of localized signals. Traffic 2019; 20:639-649. [PMID: 31206920 DOI: 10.1111/tra.12672] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/03/2019] [Accepted: 06/11/2019] [Indexed: 12/14/2022]
Abstract
Membrane-less organelles, because of their capacity to dynamically, selectively and reversibly concentrate molecules, are very well adapted for local information processing and rapid response to environmental fluctuations. These features are particularly important in the context of neuronal cells, where synapse-specific activation, or localized extracellular cues, induce signaling events restricted to specialized axonal or dendritic subcompartments. Neuronal ribonucleoprotein (RNP) particles, or granules, are nonmembrane bound macromolecular condensates that concentrate specific sets of mRNAs and regulatory proteins, promoting their long-distance transport to axons or dendrites. Neuronal RNP granules also have a dual function in regulating the translation of associated mRNAs: while preventing mRNA translation at rest, they fuel local protein synthesis upon activation. As revealed by recent work, rapid and reversible switches between these two functional modes are triggered by modifications of the networks of interactions underlying RNP granule assembly. Such flexible properties also come with a cost, as neuronal RNP granules are prone to transition into pathological aggregates in response to mutations, aging, or cellular stresses, further emphasizing the need to better understand the mechanistic principles governing their dynamic assembly and regulation in living systems.
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29
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Abstract
The molecular function and fate of mRNAs are controlled by RNA-binding proteins (RBPs). Identification of the interacting proteome of a specific mRNA in vivo remains very challenging, however. Based on the widely used technique of RNA tagging with MS2 aptamers for RNA visualization, we developed a RNA proximity biotinylation (RNA-BioID) technique by tethering biotin ligase (BirA*) via MS2 coat protein at the 3' UTR of endogenous MS2-tagged β-actin mRNA in mouse embryonic fibroblasts. We demonstrate the dynamics of the β-actin mRNA interactome by characterizing its changes on serum-induced localization of the mRNA. Apart from the previously known interactors, we identified more than 60 additional β-actin-associated RBPs by RNA-BioID. Among these, the KH domain-containing protein FUBP3/MARTA2 has been shown to be required for β-actin mRNA localization. We found that FUBP3 binds to the 3' UTR of β-actin mRNA and is essential for β-actin mRNA localization, but does not interact with the characterized β-actin zipcode element. RNA-BioID provides a tool for identifying new mRNA interactors and studying the dynamic view of the interacting proteome of endogenous mRNAs in space and time.
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30
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Wang Y, Xu C, Ma L, Mou Y, Zhang B, Zhou S, Tian Y, Trinh J, Zhang X, Li XJ. Drug screening with human SMN2 reporter identifies SMN protein stabilizers to correct SMA pathology. Life Sci Alliance 2019; 2:2/2/e201800268. [PMID: 30910806 PMCID: PMC6435041 DOI: 10.26508/lsa.201800268] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 01/14/2023] Open
Abstract
Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, is caused by reduced levels of functional survival motor neuron (SMN) protein. To identify therapeutic agents for SMA, we established a versatile SMN2-GFP reporter line by targeting the human SMN2 gene. We then screened a compound library and identified Z-FA-FMK as a potent candidate. Z-FA-FMK, a cysteine protease inhibitor, increased functional SMN through inhibiting the protease-mediated degradation of both full-length and exon 7-deleted forms of SMN. Further studies reveal that CAPN1, CAPN7, CTSB, and CTSL mediate the degradation of SMN proteins, providing novel targets for SMA. Notably, Z-FA-FMK mitigated mitochondriopathy and neuropathy in SMA patient-derived motor neurons and showed protective effects in SMA animal model after intracerebroventricular injection. E64d, another cysteine protease inhibitor which can pass through the blood-brain barrier, showed even more potent therapeutic effects after subcutaneous delivery to SMA mice. Taken together, we have successfully established a human SMN2 reporter for future drug discovery and identified the potential therapeutic value of cysteine protease inhibitors in treating SMA via stabilizing SMN proteins.
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Affiliation(s)
- Yiran Wang
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Chongchong Xu
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Lin Ma
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Reconstruction and Regeneration of Spine and Spinal Cord Injury, Ministry of Education, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, Tongji University, School of Medicine, Shanghai, China
| | - Yongchao Mou
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Bowen Zhang
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Shanshan Zhou
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yue Tian
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jessica Trinh
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA
| | - Xiaoqing Zhang
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China .,Key Laboratory of Reconstruction and Regeneration of Spine and Spinal Cord Injury, Ministry of Education, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, Tongji University, School of Medicine, Shanghai, China.,Tsingtao Advanced Research Institute, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.,Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xue-Jun Li
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA .,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
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31
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Pereira GC, Sanchez L, Schaughency PM, Rubio-Roldán A, Choi JA, Planet E, Batra R, Turelli P, Trono D, Ostrow LW, Ravits J, Kazazian HH, Wheelan SJ, Heras SR, Mayer J, García-Pérez JL, Goodier JL. Properties of LINE-1 proteins and repeat element expression in the context of amyotrophic lateral sclerosis. Mob DNA 2018; 9:35. [PMID: 30564290 PMCID: PMC6295051 DOI: 10.1186/s13100-018-0138-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/15/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving loss of motor neurons and having no known cure and uncertain etiology. Several studies have drawn connections between altered retrotransposon expression and ALS. Certain features of the LINE-1 (L1) retrotransposon-encoded ORF1 protein (ORF1p) are analogous to those of neurodegeneration-associated RNA-binding proteins, including formation of cytoplasmic aggregates. In this study we explore these features and consider possible links between L1 expression and ALS. RESULTS We first considered factors that modulate aggregation and subcellular distribution of LINE-1 ORF1p, including nuclear localization. Changes to some ORF1p amino acid residues alter both retrotransposition efficiency and protein aggregation dynamics, and we found that one such polymorphism is present in endogenous L1s abundant in the human genome. We failed, however, to identify CRM1-mediated nuclear export signals in ORF1p nor strict involvement of cell cycle in endogenous ORF1p nuclear localization in human 2102Ep germline teratocarcinoma cells. Some proteins linked with ALS bind and colocalize with L1 ORF1p ribonucleoprotein particles in cytoplasmic RNA granules. Increased expression of several ALS-associated proteins, including TAR DNA Binding Protein (TDP-43), strongly limits cell culture retrotransposition, while some disease-related mutations modify these effects. Using quantitative reverse transcription PCR (RT-qPCR) of ALS tissues and reanalysis of publicly available RNA-Seq datasets, we asked if changes in expression of retrotransposons are associated with ALS. We found minimal altered expression in sporadic ALS tissues but confirmed a previous report of differential expression of many repeat subfamilies in C9orf72 gene-mutated ALS patients. CONCLUSIONS Here we extended understanding of the subcellular localization dynamics of the aggregation-prone LINE-1 ORF1p RNA-binding protein. However, we failed to find compelling evidence for misregulation of LINE-1 retrotransposons in sporadic ALS nor a clear effect of ALS-associated TDP-43 protein on L1 expression. In sum, our study reveals that the interplay of active retrotransposons and the molecular features of ALS are more complex than anticipated. Thus, the potential consequences of altered retrotransposon activity for ALS and other neurodegenerative disorders are worthy of continued investigation.
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Affiliation(s)
- Gavin C. Pereira
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Laura Sanchez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
| | - Paul M. Schaughency
- Oncology Center-Cancer Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Alejandro Rubio-Roldán
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
| | - Jungbin A. Choi
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Evarist Planet
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ranjan Batra
- Department of Neurosciences, School of Medicine, University of California at San Diego, San Diego, California USA
| | - Priscilla Turelli
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Didier Trono
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lyle W. Ostrow
- Neuromuscular Division, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - John Ravits
- Department of Neurosciences, School of Medicine, University of California at San Diego, San Diego, California USA
| | - Haig H. Kazazian
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Sarah J. Wheelan
- Oncology Center-Cancer Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Sara R. Heras
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Jens Mayer
- Department of Human Genetics, Medical Faculty, University of Saarland, Homburg/Saar, Germany
| | - Jose Luis García-Pérez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - John L. Goodier
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
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32
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Chaytow H, Huang YT, Gillingwater TH, Faller KME. The role of survival motor neuron protein (SMN) in protein homeostasis. Cell Mol Life Sci 2018; 75:3877-3894. [PMID: 29872871 PMCID: PMC6182345 DOI: 10.1007/s00018-018-2849-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 12/11/2022]
Abstract
Ever since loss of survival motor neuron (SMN) protein was identified as the direct cause of the childhood inherited neurodegenerative disorder spinal muscular atrophy, significant efforts have been made to reveal the molecular functions of this ubiquitously expressed protein. Resulting research demonstrated that SMN plays important roles in multiple fundamental cellular homeostatic pathways, including a well-characterised role in the assembly of the spliceosome and biogenesis of ribonucleoproteins. More recent studies have shown that SMN is also involved in other housekeeping processes, including mRNA trafficking and local translation, cytoskeletal dynamics, endocytosis and autophagy. Moreover, SMN has been shown to influence mitochondria and bioenergetic pathways as well as regulate function of the ubiquitin-proteasome system. In this review, we summarise these diverse functions of SMN, confirming its key role in maintenance of the homeostatic environment of the cell.
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Affiliation(s)
- Helena Chaytow
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Yu-Ting Huang
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
| | - Kiterie M E Faller
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
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33
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Mertsch S, Schlicht K, Melkonyan H, Schlatt S, Thanos S. snRPN controls the ability of neurons to regenerate axons. Restor Neurol Neurosci 2018; 36:31-43. [PMID: 29439367 DOI: 10.3233/rnn-170780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Retinal ganglion cells (RGCs) of mammals lose the ability to regenerate injured axons during postnatal maturation, but little is known about the underlying molecular mechanisms. OBJECTIVE It remains of particular importance to understand the mechanisms of axonal regeneration to develop new therapeutic approaches for nerve injuries. METHODS Retinas from newborn to adult monkeys (Callithrix jacchus)1 were obtained immediately after death and cultured in vitro. Growths of axons were monitored using microscopy and time-lapse video cinematography. Immunohistochemistry, Western blotting, qRT-PCR, and genomics were performed to characterize molecules associated with axonal regeneration and growth. A genomic screen was performed by using retinal explants versus native and non-regenerative explants obtained from eye cadavers on the day of birth, and hybridizing the mRNA with cross-reacting cDNA on conventional human microarrays. Followed the genomic screen, siRNA experiments were conducted to identify the functional involvement of identified candidates. RESULTS Neuron-specific human ribonucleoprotein N (snRPN) was found to be a potential regulator of impaired axonal regeneration during neuronal maturation in these animals. In particular, up-regulation of snRPN was observed during retinal maturation, coinciding with a decline in regenerative ability. Axon regeneration was reactivated in snRPN-knockout retinal ex vivo explants of adult monkey. CONCLUSION These results suggest that coordinated snRPN-driven activities within the neuron-specific ribonucleoprotein complex regulate the regenerative ability of RGCs in primates, thereby highlighting a potential new role for snRPN within neurons and the possibility of novel postinjury therapies.
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Affiliation(s)
- Sonja Mertsch
- Institute of Experimental Ophthalmology and DFG-Excellence Center, Cells in Motion (CiM, area C.4), School of Medicine, University of Münster, Münster, Germany.,Department of Ophthalmology, Laboratory of Experimental Ophthalmology, University Clinic Duesseldorf, Duesseldorf, Germany
| | - Katrin Schlicht
- Institute of Experimental Ophthalmology and DFG-Excellence Center, Cells in Motion (CiM, area C.4), School of Medicine, University of Münster, Münster, Germany
| | - Harutyun Melkonyan
- Institute of Experimental Ophthalmology and DFG-Excellence Center, Cells in Motion (CiM, area C.4), School of Medicine, University of Münster, Münster, Germany
| | - Stefan Schlatt
- Institute of Regenerative Medicine (CeRA) and DFG-Excellence Center, Cells in Motion (CiM, area A.2), School of Medicine, University of Münster, Münster, Germany
| | - Solon Thanos
- Institute of Experimental Ophthalmology and DFG-Excellence Center, Cells in Motion (CiM, area C.4), School of Medicine, University of Münster, Münster, Germany
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34
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Leung KM, Lu B, Wong HHW, Lin JQ, Turner-Bridger B, Holt CE. Cue-Polarized Transport of β-actin mRNA Depends on 3'UTR and Microtubules in Live Growth Cones. Front Cell Neurosci 2018; 12:300. [PMID: 30250426 PMCID: PMC6139529 DOI: 10.3389/fncel.2018.00300] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 08/17/2018] [Indexed: 11/13/2022] Open
Abstract
Guidance cues trigger fast responses in axonal growth cones such as directional turning and collapse that require local protein synthesis. An attractive cue-gradient, such as Netrin-1, triggers de novo synthesis of β-actin localized to the near-side compartment of the growth cone that promotes F-actin assembly and attractive steering. How this precise spatial asymmetry in mRNA translation arises across the small expanse of the growth cone is poorly understood. Pre-localized mRNAs in the vicinity of activated receptors could be selectively translated and/or new mRNAs could be trafficked into the area. Here we have performed live imaging of fluorescent-tagged β-actin mRNA to investigate mRNA trafficking dynamics in Xenopus retinal ganglion cell (RGC) axons and growth cones in response to Netrin-1. A Netrin-1 gradient was found to elicit the transport of β-actin mRNA granules to the near-side of growth cones within a 4-7 min window. This polarized mRNA trafficking depended on the 3' untranslated region (UTR) since mRNA-Δ3'UTR mutant failed to exhibit cue-induced localization. Global application of Netrin-1 significantly increased the anterograde movement of β-actin mRNA along axons and also promoted microtubule-dependent mRNA excursions from the central domain of the growth cone into the periphery (filopodia and lamellipodia). Dual channel imaging revealed β-actin mRNA riding behind the microtubule plus-end tracking protein, EB1, in movements along dynamic microtubules into filopodia. The mRNA-EB1 movements were unchanged by a Netrin-1 gradient indicating the dynamic microtubules themselves do not underlie the cue-induced polarity of RNA movement. Finally, fast-moving elongated "worm-like" trains of Cy3-RNA, distinct from mitochondria, were seen transporting RNA along axons in vitro and in vivo suggesting the existence of a novel transport organelle. Overall, the results provide evidence that the axonal trafficking of β-actin mRNA can be regulated by the guidance cue Netrin-1 to transduce the polarity of an extracellular stimulus and that the 3'UTR is essential for this cue-induced regulation.
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Affiliation(s)
| | | | | | | | | | - Christine E. Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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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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Abstract
Autosomal-recessive proximal spinal muscular atrophy (Werdnig-Hoffmann, Kugelberg-Welander) is caused by mutation of the SMN1 gene, and the clinical severity correlates with the number of copies of a nearly identical gene, SMN2. The SMN protein plays a critical role in spliceosome assembly and may have other cellular functions, such as mRNA transport. Cell culture and animal models have helped to define the disease mechanism and to identify targets for therapeutic intervention. The main focus for developing treatment has been to increase SMN levels, and accomplishing this with small molecules, oligonucleotides, and gene replacement has been quite. An oligonucleotide, nusinersen, was recently approved for treatment in patients, and confirmatory studies of other agents are now under way.
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Affiliation(s)
- Eveline S Arnold
- Neurogenetics Branch, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Kenneth H Fischbeck
- Neurogenetics Branch, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States.
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Ravanidis S, Kattan FG, Doxakis E. Unraveling the Pathways to Neuronal Homeostasis and Disease: Mechanistic Insights into the Role of RNA-Binding Proteins and Associated Factors. Int J Mol Sci 2018; 19:ijms19082280. [PMID: 30081499 PMCID: PMC6121432 DOI: 10.3390/ijms19082280] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 07/26/2018] [Accepted: 07/31/2018] [Indexed: 12/13/2022] Open
Abstract
The timing, dosage and location of gene expression are fundamental determinants of brain architectural complexity. In neurons, this is, primarily, achieved by specific sets of trans-acting RNA-binding proteins (RBPs) and their associated factors that bind to specific cis elements throughout the RNA sequence to regulate splicing, polyadenylation, stability, transport and localized translation at both axons and dendrites. Not surprisingly, misregulation of RBP expression or disruption of its function due to mutations or sequestration into nuclear or cytoplasmic inclusions have been linked to the pathogenesis of several neuropsychiatric and neurodegenerative disorders such as fragile-X syndrome, autism spectrum disorders, spinal muscular atrophy, amyotrophic lateral sclerosis and frontotemporal dementia. This review discusses the roles of Pumilio, Staufen, IGF2BP, FMRP, Sam68, CPEB, NOVA, ELAVL, SMN, TDP43, FUS, TAF15, and TIA1/TIAR in RNA metabolism by analyzing their specific molecular and cellular function, the neurological symptoms associated with their perturbation, and their axodendritic transport/localization along with their target mRNAs as part of larger macromolecular complexes termed ribonucleoprotein (RNP) granules.
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Affiliation(s)
- Stylianos Ravanidis
- Basic Sciences Division I, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece.
| | - Fedon-Giasin Kattan
- Basic Sciences Division I, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece.
| | - Epaminondas Doxakis
- Basic Sciences Division I, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece.
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Beattie CE, Kolb SJ. Spinal muscular atrophy: Selective motor neuron loss and global defect in the assembly of ribonucleoproteins. Brain Res 2018; 1693:92-97. [DOI: 10.1016/j.brainres.2018.02.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 02/10/2018] [Accepted: 02/15/2018] [Indexed: 12/13/2022]
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39
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Surrey V, Zöller C, Lork AA, Moradi M, Balk S, Dombert B, Saal-Bauernschubert L, Briese M, Appenzeller S, Fischer U, Jablonka S. Impaired Local Translation of β-actin mRNA in Ighmbp2-Deficient Motoneurons: Implications for Spinal Muscular Atrophy with respiratory Distress (SMARD1). Neuroscience 2018; 386:24-40. [DOI: 10.1016/j.neuroscience.2018.06.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/03/2018] [Accepted: 06/11/2018] [Indexed: 12/31/2022]
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40
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Jha NN, Kim JK, Monani UR. Motor neuron biology and disease: A current perspective on infantile-onset spinal muscular atrophy. FUTURE NEUROLOGY 2018; 13:161-172. [PMID: 31396020 DOI: 10.2217/fnl-2018-0008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Infantile-onset spinal muscular atrophy (SMA) is a prototypical disease in which to investigate selective neurodegenerative phenotypes. Caused by low levels of the ubiquitously expressed Survival Motor Neuron (SMN) protein, the disease mainly targets the spinal motor neurons. This selective phenotype remains largely unexplained, but has not hindered the development of SMN repletion as a means to a treatment. Here we chronicle recent advances in the area of SMA biology. We provide a brief background to the disease, highlight major advances that have shaped our current understanding of SMA, trace efforts to treat the condition, discuss the outcome of two promising new therapies and conclude by considering contemporary as well as new challenges stemming from recent successes within the field.
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Affiliation(s)
- Narendra N Jha
- Department of Pathology & Cell Biology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Center for Motor Neuron Biology & Disease, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032
| | - Jeong-Ki Kim
- Department of Pathology & Cell Biology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Center for Motor Neuron Biology & Disease, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032
| | - Umrao R Monani
- Department of Pathology & Cell Biology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Department of Neurology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Center for Motor Neuron Biology & Disease, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032
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41
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Rodriguez-Muela N, Parkhitko A, Grass T, Gibbs RM, Norabuena EM, Perrimon N, Singh R, Rubin LL. Blocking p62-dependent SMN degradation ameliorates spinal muscular atrophy disease phenotypes. J Clin Invest 2018; 128:3008-3023. [PMID: 29672276 DOI: 10.1172/jci95231] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 04/12/2018] [Indexed: 12/13/2022] Open
Abstract
Spinal muscular atrophy (SMA), a degenerative motor neuron (MN) disease, caused by loss of functional survival of motor neuron (SMN) protein due to SMN1 gene mutations, is a leading cause of infant mortality. Increasing SMN levels ameliorates the disease phenotype and is unanimously accepted as a therapeutic approach for patients with SMA. The ubiquitin/proteasome system is known to regulate SMN protein levels; however, whether autophagy controls SMN levels remains poorly explored. Here, we show that SMN protein is degraded by autophagy. Pharmacological and genetic inhibition of autophagy increases SMN levels, while induction of autophagy decreases these levels. SMN degradation occurs via its interaction with the autophagy adapter p62 (also known as SQSTM1). We also show that SMA neurons display reduced autophagosome clearance, increased p62 and ubiquitinated proteins levels, and hyperactivated mTORC1 signaling. Importantly, reducing p62 levels markedly increases SMN and its binding partner gemin2, promotes MN survival, and extends lifespan in fly and mouse SMA models, revealing p62 as a potential new therapeutic target for the treatment of SMA.
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Affiliation(s)
- Natalia Rodriguez-Muela
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Andrey Parkhitko
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Tobias Grass
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Rebecca M Gibbs
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Erika M Norabuena
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.,Howard Hughes Medical Institute, Boston, Massachusetts, USA
| | - Rajat Singh
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
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Thompson LW, Morrison KD, Shirran SL, Groen EJN, Gillingwater TH, Botting CH, Sleeman JE. Neurochondrin interacts with the SMN protein suggesting a novel mechanism for spinal muscular atrophy pathology. J Cell Sci 2018; 131:jcs.211482. [PMID: 29507115 PMCID: PMC5963842 DOI: 10.1242/jcs.211482] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 02/16/2018] [Indexed: 12/15/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an inherited neurodegenerative condition caused by a reduction in the amount of functional survival motor neuron (SMN) protein. SMN has been implicated in transport of mRNA in neural cells for local translation. We previously identified microtubule-dependent mobile vesicles rich in SMN and SNRPB, a member of the Sm family of small nuclear ribonucleoprotein (snRNP)-associated proteins, in neural cells. By comparing the interactomes of SNRPB and SNRPN, a neural-specific Sm protein, we now show that the essential neural protein neurochondrin (NCDN) interacts with Sm proteins and SMN in the context of mobile vesicles in neurites. NCDN has roles in protein localisation in neural cells and in maintenance of cell polarity. NCDN is required for the correct localisation of SMN, suggesting they may both be required for formation and transport of trafficking vesicles. NCDN may have potential as a therapeutic target for SMA together with, or in place of the targeting of SMN expression. This article has an associated First Person interview with the first author of the paper. Highlighted Article: The essential neural protein neurochondrin interacts with the spinal muscular atrophy (SMA) protein SMN in cell lines and in mice. This might be relevant to the molecular pathology of SMA.
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Affiliation(s)
- Luke W Thompson
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Kim D Morrison
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Sally L Shirran
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Ewout J N Groen
- Edinburgh Medical School, Biomedical Sciences and Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Thomas H Gillingwater
- Edinburgh Medical School, Biomedical Sciences and Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Catherine H Botting
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Judith E Sleeman
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
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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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Magri F, Vanoli F, Corti S. miRNA in spinal muscular atrophy pathogenesis and therapy. J Cell Mol Med 2017; 22:755-767. [PMID: 29160009 PMCID: PMC5783860 DOI: 10.1111/jcmm.13450] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 10/03/2017] [Indexed: 02/06/2023] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease characterized by the selective death of lower motor neurons in the brain stem and spinal cord. SMA is caused by mutations in the survival motor neuron 1 gene (SMN1), leading to the reduced expression of the full-length SMN protein. microRNAs (miRNAs) are small RNAs that regulate post-transcriptional gene expression. Recent findings have suggested an important role for miRNAs in the pathogenesis of motor neuron diseases, including SMA. Motor neuron-specific miRNA dysregulation in SMA might be implicated in their selective vulnerability. In this study, we discuss recent findings regarding the consequences of SMN defects on miRNAs and their target mRNAs in motor neurons. Taken together, these data suggest that cell-specific changes in miRNAs are not only involved in the SMA motor neuron phenotype but can also be used as biomarkers and therapeutic targets.
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Affiliation(s)
- Francesca Magri
- Dino Ferrari Center, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Fiammetta Vanoli
- Dino Ferrari Center, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.,Department of Neurological Sciences, Mental Health and Sensory Organs (NESMOS), "Sapienza" University of Rome, Rome, Italy
| | - Stefania Corti
- Dino Ferrari Center, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
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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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46
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Dysregulation of mRNA Localization and Translation in Genetic Disease. J Neurosci 2017; 36:11418-11426. [PMID: 27911744 DOI: 10.1523/jneurosci.2352-16.2016] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/01/2016] [Accepted: 09/02/2016] [Indexed: 11/21/2022] Open
Abstract
RNA-binding proteins (RBPs) acting at various steps in the post-transcriptional regulation of gene expression play crucial roles in neuronal development and synaptic plasticity. Genetic mutations affecting several RBPs and associated factors lead to diverse neurological symptoms, as characterized by neurodevelopmental and neuropsychiatric disorders, neuromuscular and neurodegenerative diseases, and can often be multisystemic diseases. We will highlight the physiological roles of a few specific proteins in molecular mechanisms of cytoplasmic mRNA regulation, and how these processes are dysregulated in genetic disease. Recent advances in computational biology and genomewide analysis, integrated with diverse experimental approaches and model systems, have provided new insights into conserved mechanisms and the shared pathobiology of mRNA dysregulation in disease. Progress has been made to understand the pathobiology of disease mechanisms for myotonic dystrophy, spinal muscular atrophy, and fragile X syndrome, with broader implications for other RBP-associated genetic neurological diseases. This gained knowledge of underlying basic mechanisms has paved the way to the development of therapeutic strategies targeting disease mechanisms.
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47
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Abstract
Cells are highly organized entities that rely on intricate addressing mechanisms to sort their constituent molecules to precise subcellular locations. These processes are crucial for cells to maintain their proper organization and carry out specialized functions in the body, consequently genetic perturbations that clog up these addressing systems can contribute to disease aetiology. The trafficking of RNA molecules represents an important layer in the control of cellular organization, a process that is both highly prevalent and for which features of the regulatory machineries have been deeply conserved evolutionarily. RNA localization is commonly driven by trans-regulatory factors, including RNA binding proteins at the core, which recognize specific cis-acting zipcode elements within the RNA transcripts. Here, we first review the functions and biological benefits of intracellular RNA trafficking, from the perspective of both coding and non-coding RNAs. Next, we discuss the molecular mechanisms that modulate this localization, emphasizing the diverse features of the cis- and trans-regulators involved, while also highlighting emerging technologies and resources that will prove instrumental in deciphering RNA targeting pathways. We then discuss recent findings that reveal how co-transcriptional regulatory mechanisms operating in the nucleus can dictate the downstream cytoplasmic localization of RNAs. Finally, we survey the growing number of human diseases in which RNA trafficking pathways are impacted, including spinal muscular atrophy, Alzheimer's disease, fragile X syndrome and myotonic dystrophy. Such examples highlight the need to further dissect RNA localization mechanisms, which could ultimately pave the way for the development of RNA-oriented diagnostic and therapeutic strategies. This article is part of a Special Issue entitled "Biochemistry of Synthetic Biology - Recent Developments" Guest Editor: Dr. Ilka Heinemann and Dr. Patrick O'Donoghue.
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Affiliation(s)
- Ashley Chin
- Institut de recherches cliniques de Montréal (IRCM), 110 Avenue des Pins Ouest, Montreal, Quebec, Canada; Division of Experimental Medicine, McGill University, 1001 Decarie Boulevard, Montreal, Quebec, Canada
| | - Eric Lécuyer
- Institut de recherches cliniques de Montréal (IRCM), 110 Avenue des Pins Ouest, Montreal, Quebec, Canada; Division of Experimental Medicine, McGill University, 1001 Decarie Boulevard, Montreal, Quebec, Canada; Department of Biochemistry and Molecular Medicine, University of Montreal, 2900 Boulevard Edouard-Montpetit, Montreal, Quebec, Canada.
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48
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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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49
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Hawley ZCE, Campos-Melo D, Droppelmann CA, Strong MJ. MotomiRs: miRNAs in Motor Neuron Function and Disease. Front Mol Neurosci 2017; 10:127. [PMID: 28522960 PMCID: PMC5415563 DOI: 10.3389/fnmol.2017.00127] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 04/18/2017] [Indexed: 12/12/2022] Open
Abstract
MiRNAs are key regulators of the mammalian transcriptome that have been increasingly linked to degenerative diseases of the motor neurons. Although many of the miRNAs currently incriminated as participants in the pathogenesis of these diseases are also important to the normal development and function of motor neurons, at present there is no knowledge of the complete miRNA profile of motor neurons. In this review, we examine the current understanding with respect to miRNAs that are specifically required for motor neuron development, function and viability, and provide evidence that these should be considered as a functional network of miRNAs which we have collectively termed MotomiRs. We will also summarize those MotomiRs currently known to be associated with both amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), and discuss their potential use as biomarkers.
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Affiliation(s)
- Zachary C E Hawley
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western UniversityLondon, ON, Canada
| | - Danae Campos-Melo
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western UniversityLondon, ON, Canada
| | - Cristian A Droppelmann
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western UniversityLondon, ON, Canada
| | - Michael J Strong
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western UniversityLondon, ON, Canada.,Department of Pathology, Schulich School of Medicine and Dentistry, Western UniversityLondon, ON, Canada.,Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western UniversityLondon, ON, Canada
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50
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Farrelly-Rosch A, Lau CL, Patil N, Turner BJ, Shabanpoor F. Combination of valproic acid and morpholino splice-switching oligonucleotide produces improved outcomes in spinal muscular atrophy patient-derived fibroblasts. Neurochem Int 2017; 108:213-221. [PMID: 28389270 DOI: 10.1016/j.neuint.2017.02.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 02/22/2017] [Accepted: 02/24/2017] [Indexed: 12/16/2022]
Abstract
Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality worldwide, is characterised by the homozygous loss of the survival motor neuron 1 (SMN1) gene. The consequent degeneration of spinal motor neurons and progressive atrophy of voluntary muscle groups results in paralysis and eventually premature infantile death. Humans possess a second nearly identical copy of SMN1, known as SMN2. However, SMN2 produces only 10-20% functional SMN protein due to aberrant splicing of its pre-mRNA that leads to the exclusion of exon 7. This level of SMN is insufficient to rescue the phenotype. Recently developed splice-switching antisense oligonuclotides (SSO) have shown great promise in correcting the aberrant splicing of SMN2 towards producing functional SMN protein. Several FDA approved drugs are being repurposed for SMA treatment including valproic acid (VPA), a histone deacetylase inhibitor, which has been shown to increase overall SMN2 expression. In this study, we have characterised the effects of single and combined treatment of VPA and a SSO based on phosphorodiamidate morpholino oligomer (PMO) chemistry. We conjugated both VPA and PMO to a single cell-penetrating peptide (Apolipoprotein E (ApoE)) for their simultaneous intracellular delivery. Treatment of SMA Type I patient-derived fibroblasts with the conjugates showed no additive increase in the level of full-length SMN2 mRNA expression over both 4 and 16 h treatments indicating that conjugation of VPA to ApoE-PMO has limited benefit. However, treatment with a combination of VPA and ApoE-PMO induced more favourable splice switching activity than either agent alone, promoting exon 7 inclusion in SMN2 transcripts. Our results suggest that combination therapy of VPA and ApoE-PMO is superior in upregulating SMN2 production in vitro, as compared to singular treatment of each compound at both transcriptional and protein levels. This study provides the first indication of a novel dual therapy approach for the potential treatment of SMA.
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Affiliation(s)
- Anna Farrelly-Rosch
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria 3052, Australia
| | - Chew Ling Lau
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria 3052, Australia
| | - Nitin Patil
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria 3052, Australia
| | - Bradley J Turner
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria 3052, Australia
| | - Fazel Shabanpoor
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria 3052, Australia; School of Chemistry, University of Melbourne, Victoria 3052, Australia.
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