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Brandão-Teles C, Antunes ASLM, de Moraes Vrechi TA, Martins-de-Souza D. The Roles of hnRNP Family in the Brain and Brain-Related Disorders. Mol Neurobiol 2024; 61:3578-3595. [PMID: 37999871 DOI: 10.1007/s12035-023-03747-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/25/2023] [Indexed: 11/25/2023]
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) belong to a complex family of RNA-binding proteins that are essential to control alternative splicing, mRNA trafficking, synaptic plasticity, stress granule formation, cell cycle regulation, and axonal transport. Over the past decade, hnRNPs have been associated with different brain disorders such as Alzheimer's disease, multiple sclerosis, and schizophrenia. Given their essential role in maintaining cell function and integrity, it is not surprising that dysregulated hnRNP levels lead to neurological implications. This review aims to explore the primary functions of hnRNPs in neurons, oligodendrocytes, microglia, and astrocytes, and their roles in brain disorders. We also discuss proteomics and other technologies and their potential for studying and evaluating hnRNPs in brain disorders, including the discovery of new therapeutic targets and possible pharmacological interventions.
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Affiliation(s)
- Caroline Brandão-Teles
- Laboratory of Neuroproteomics, Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, Campinas, Brazil.
| | - André S L M Antunes
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - Talita Aparecida de Moraes Vrechi
- Laboratory of Neuroproteomics, Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, Campinas, Brazil
| | - Daniel Martins-de-Souza
- Laboratory of Neuroproteomics, Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, Campinas, Brazil.
- D'Or Institute for Research and Education (IDOR), São Paulo, Brazil.
- Experimental Medicine Research Cluster (EMRC), University of Campinas, Campinas, SP, 13083-862, Brazil.
- INCT in Modelling Human Complex Diseases with 3D Platforms (Model3D), São Paulo, Brazil.
- Conselho Nacional de Desenvolvimento Científico e Tecnológico, Instituto Nacional de Biomarcadores em Neuropsiquiatria, São Paulo, Brazil.
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2
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Tan WH, Rücklin M, Larionova D, Ngoc TB, Joan van Heuven B, Marone F, Matsudaira P, Winkler C. A Collagen10a1 mutation disrupts cell polarity in a medaka model for metaphyseal chondrodysplasia type Schmid. iScience 2024; 27:109405. [PMID: 38510140 PMCID: PMC10952040 DOI: 10.1016/j.isci.2024.109405] [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: 09/26/2023] [Revised: 12/21/2023] [Accepted: 02/29/2024] [Indexed: 03/22/2024] Open
Abstract
Heterozygous mutations in COL10A1 lead to metaphyseal chondrodysplasia type Schmid (MCDS), a skeletal disorder characterized by epiphyseal abnormalities. Prior analysis revealed impaired trimerization and intracellular retention of mutant collagen type X alpha 1 chains as cause for elevated endoplasmic reticulum (ER) stress. However, how ER stress translates into structural defects remained unclear. We generated a medaka (Oryzias latipes) MCDS model harboring a 5 base pair deletion in col10a1, which led to a frameshift and disruption of 11 amino acids in the conserved trimerization domain. col10a1Δ633a heterozygotes recapitulated key features of MCDS and revealed early cell polarity defects as cause for dysregulated matrix secretion and deformed skeletal structures. Carbamazepine, an ER stress-reducing drug, rescued this polarity impairment and alleviated skeletal defects in col10a1Δ633a heterozygotes. Our data imply cell polarity dysregulation as a potential contributor to MCDS and suggest the col10a1Δ633a medaka mutant as an attractive MCDS animal model for drug screening.
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Affiliation(s)
- Wen Hui Tan
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Martin Rücklin
- Naturalis Biodiversity Center, Postbus 9517, 2300 RA Leiden, the Netherlands
| | - Daria Larionova
- Department of Biology, Research Group Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
| | - Tran Bich Ngoc
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | | | - Federica Marone
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Paul Matsudaira
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Christoph Winkler
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
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3
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Dithmar S, Zare A, Salehi S, Briese M, Sendtner M. hnRNP R regulates mitochondrial movement and membrane potential in axons of motoneurons. Neurobiol Dis 2024; 193:106454. [PMID: 38408684 DOI: 10.1016/j.nbd.2024.106454] [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: 12/12/2023] [Revised: 02/12/2024] [Accepted: 02/23/2024] [Indexed: 02/28/2024] Open
Abstract
Axonal mitochondria defects are early events in the pathogenesis of motoneuron disorders such as spinal muscular atrophy and amyotrophic lateral sclerosis. The RNA-binding protein hnRNP R interacts with different motoneuron disease-related proteins such as SMN and TDP-43 and has important roles in axons of motoneurons, including axonal mRNA transport. However, whether hnRNP R also modulates axonal mitochondria is currently unknown. Here, we show that axonal mitochondria exhibit altered function and motility in hnRNP R-deficient motoneurons. Motoneurons lacking hnRNP R show decreased anterograde and increased retrograde transport of mitochondria in axons. Furthermore, hnRNP R-deficiency leads to mitochondrial hyperpolarization, caused by decreased complex I and reversed complex V activity within the respiratory chain. Taken together, our data indicate a role for hnRNP R in regulating transport and maintaining functionality of axonal mitochondria in motoneurons.
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Affiliation(s)
- Sophia Dithmar
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Abdolhossein Zare
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Saeede Salehi
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
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4
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Jiang Y, Conradt B. A genetic screen identifies C. elegans eif-3.H and hrpr-1 as pro-apoptotic genes and potential activators of egl-1 expression. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001126. [PMID: 38434221 PMCID: PMC10905296 DOI: 10.17912/micropub.biology.001126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/09/2024] [Accepted: 02/14/2024] [Indexed: 03/05/2024]
Abstract
During C. elegans development, 1090 somatic cells are generated of which 131 reproducibly die, many through apoptosis. The C. elegans BH3-only gene egl-1 is the key activator of apoptosis in somatic tissues, and it is predominantly expressed in 'cell death' lineages i.e. lineages in which apoptotic cell death occurs. egl-1 expression is regulated at the transcriptional and post-transcriptional level. For example, we previously showed that the miR-35 and miR-58 families of miRNAs repress egl-1 expression in mothers of 'unwanted' cells by binding to the 3' UTR of egl-1 mRNA, thereby increasing egl-1 mRNA turnover. In a screen for RNA-binding proteins with a role in the post-transcriptional control of egl-1 expression, we identified EIF-3.H (ortholog of human eIF3H) and HRPR-1 (ortholog human hnRNP R/Q) as potential activators of egl-1 expression. In addition, we demonstrate that the knockdown of the eif-3.H or hrpr-1 gene by RNA-mediated interference (RNAi) results in the inappropriate survival of unwanted cells during C. elegans development. Our study provides novel insight into how egl-1 expression is controlled to cause the reproducible pattern of cell death observed during C. elegans development.
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Affiliation(s)
- Yanwen Jiang
- Cell and Developmental Biology, University College London
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5
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Jia Q, Tan Y, Li Y, Wu Y, Wang J, Tang F. JUN-induced super-enhancer RNA forms R-loop to promote nasopharyngeal carcinoma metastasis. Cell Death Dis 2023; 14:459. [PMID: 37479693 PMCID: PMC10361959 DOI: 10.1038/s41419-023-05985-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 07/10/2023] [Accepted: 07/12/2023] [Indexed: 07/23/2023]
Abstract
Oncogenic super-enhancers (SEs) generate noncoding enhancer/SE RNAs (eRNAs/seRNAs) that exert a critical function in malignancy through powerful regulation of target gene expression. Herein, we show that a JUN-mediated seRNA can form R-loop to regulate target genes to promote metastasis of nasopharyngeal carcinoma (NPC). A combination of global run-on sequencing, chromatin-immunoprecipitation sequencing, and RNA sequencing was used to screen seRNAs. A specific seRNA associated with NPC metastasis (seRNA-NPCM) was identified as a transcriptional regulator for N-myc downstream-regulated gene 1 (NDRG1). JUN was found to regulate seRNA-NPCM through motif binding. seRNA-NPCM was elevated in NPC cancer tissues and highly metastatic cell lines, and promoted the metastasis of NPC cells in vitro and in vivo. Mechanistically, the 3' end of seRNA-NPCM hybridizes with the SE region to form an R-loop, and the middle segment of seRNA-NPCM binds to heterogeneous nuclear ribonucleoprotein R (hnRNPR) at the promoter of distal gene NDRG1 and neighboring gene tribbles pseudokinase 1 (TRIB1). These structures promote chromatin looping and long-distance chromatin interactions between SEs and promoters, thus facilitating NDRG1 and TRIB1 transcription. Furthermore, the clinical analyses showed that seRNA-NPCM and NDRG1 were independent prognostic factors for NPC patients. seRNA-NPCM plays a critical role in orchestrating target gene transcription to promote NPC metastasis.
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Affiliation(s)
- Qunying Jia
- Hunan Key Laboratory of Oncotarget Gene and Clinical Laboratory, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University/Hunan Cancer Hospital, 410013, Changsha, China
| | - Yuan Tan
- Hunan Key Laboratory of Oncotarget Gene and Clinical Laboratory, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University/Hunan Cancer Hospital, 410013, Changsha, China
| | - Yuejin Li
- Hunan Key Laboratory of Oncotarget Gene and Clinical Laboratory, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University/Hunan Cancer Hospital, 410013, Changsha, China
| | - Yao Wu
- Hunan Key Laboratory of Oncotarget Gene and Clinical Laboratory, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University/Hunan Cancer Hospital, 410013, Changsha, China
- Department of Ophthalmology and Otolaryngology, The First Hospital of Hunan University of Chinese Medicine, 410208, Changsha, China
| | - Jing Wang
- Hunan Key Laboratory of Oncotarget Gene and Clinical Laboratory, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University/Hunan Cancer Hospital, 410013, Changsha, China
| | - Faqin Tang
- Hunan Key Laboratory of Oncotarget Gene and Clinical Laboratory, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University/Hunan Cancer Hospital, 410013, Changsha, China.
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6
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Salehi S, Zare A, Prezza G, Bader J, Schneider C, Fischer U, Meissner F, Mann M, Briese M, Sendtner M. Cytosolic Ptbp2 modulates axon growth in motoneurons through axonal localization and translation of Hnrnpr. Nat Commun 2023; 14:4158. [PMID: 37438340 DOI: 10.1038/s41467-023-39787-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 06/28/2023] [Indexed: 07/14/2023] Open
Abstract
The neuronal RNA-binding protein Ptbp2 regulates neuronal differentiation by modulating alternative splicing programs in the nucleus. Such programs contribute to axonogenesis by adjusting the levels of protein isoforms involved in axon growth and branching. While its functions in alternative splicing have been described in detail, cytosolic roles of Ptbp2 for axon growth have remained elusive. Here, we show that Ptbp2 is located in the cytosol including axons and growth cones of motoneurons, and that depletion of cytosolic Ptbp2 affects axon growth. We identify Ptbp2 as a major interactor of the 3' UTR of Hnrnpr mRNA encoding the RNA-binding protein hnRNP R. Axonal localization of Hnrnpr mRNA and local synthesis of hnRNP R protein are strongly reduced when Ptbp2 is depleted, leading to defective axon growth. Ptbp2 regulates hnRNP R translation by mediating the association of Hnrnpr with ribosomes in a manner dependent on the translation factor eIF5A2. Our data thus suggest a mechanism whereby cytosolic Ptbp2 modulates axon growth by fine-tuning the mRNA transport and local synthesis of an RNA-binding protein.
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Affiliation(s)
- Saeede Salehi
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Abdolhossein Zare
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Gianluca Prezza
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Wuerzburg, Germany
| | - Jakob Bader
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Cornelius Schneider
- Department of Biochemistry, Theodor Boveri Institute, University of Wuerzburg, Wuerzburg, Germany
| | - Utz Fischer
- Department of Biochemistry, Theodor Boveri Institute, University of Wuerzburg, Wuerzburg, Germany
| | - Felix Meissner
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Martinsried, Germany
- Institute of Innate Immunity, Department of Systems Immunology and Proteomics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
- NNF Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
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7
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Lins ÉM, Oliveira NCM, Reis O, Ferrasa A, Herai R, Muotri AR, Massirer KB, Bengtson MH. Genome-wide translation control analysis of developing human neurons. Mol Brain 2022; 15:55. [PMID: 35706057 PMCID: PMC9199153 DOI: 10.1186/s13041-022-00940-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/29/2022] [Indexed: 11/25/2022] Open
Abstract
During neuronal differentiation, neuroprogenitor cells become polarized, change shape, extend axons, and form complex dendritic trees. While growing, axons are guided by molecular cues to their final destination, where they establish synaptic connections with other neuronal cells. Several layers of regulation are integrated to control neuronal development properly. Although control of mRNA translation plays an essential role in mammalian gene expression, how it contributes temporarily to the modulation of later stages of neuronal differentiation remains poorly understood. Here, we investigated how translation control affects pathways and processes essential for neuronal maturation, using H9-derived human neuro progenitor cells differentiated into neurons as a model. Through Ribosome Profiling (Riboseq) combined with RNA sequencing (RNAseq) analysis, we found that translation control regulates the expression of critical hub genes. Fundamental synaptic vesicle secretion genes belonging to SNARE complex, Rab family members, and vesicle acidification ATPases are strongly translationally regulated in developing neurons. Translational control also participates in neuronal metabolism modulation, particularly affecting genes involved in the TCA cycle and glutamate synthesis/catabolism. Importantly, we found translation regulation of several critical genes with fundamental roles regulating actin and microtubule cytoskeleton pathways, critical to neurite generation, spine formation, axon guidance, and circuit formation. Our results show that translational control dynamically integrates important signals in neurons, regulating several aspects of its development and biology.
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Affiliation(s)
- Érico Moreto Lins
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas-UNICAMP, Campinas, SP, 13083-970, Brazil.,Graduate Program in Genetics and Molecular Biology (PGBM), UNICAMP, Campinas, SP, 13083-886, Brazil
| | - Natássia Cristina Martins Oliveira
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas-UNICAMP, Campinas, SP, 13083-970, Brazil.,Center of Medicinal Chemistry-CQMED, Structural Genomics Consortium-SGC, University of Campinas-UNICAMP, Campinas, SP, 13083-886, Brazil
| | - Osvaldo Reis
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas-UNICAMP, Campinas, SP, 13083-970, Brazil
| | - Adriano Ferrasa
- School of Medicine, Graduate Program in Health Sciences, Pontifícia Universidade Católica do Paraná, Curitiba, PR, 80215-901, Brazil.,Department of Computer Science, State University of Ponta Grossa-UEPG, Ponta Grossa, PR, 84030-900, Brazil
| | - Roberto Herai
- School of Medicine, Graduate Program in Health Sciences, Pontifícia Universidade Católica do Paraná, Curitiba, PR, 80215-901, Brazil
| | - Alysson R Muotri
- Department of Pediatrics and Cellular and Molecular Medicine, School of Medicine, UC San Diego, La Jolla, CA, 92037, Brazil
| | - Katlin Brauer Massirer
- Center for Molecular Biology and Genetic Engineering-CBMEG, University of Campinas-UNICAMP, Campinas, SP, 13083-875, Brazil.,Center of Medicinal Chemistry-CQMED, Structural Genomics Consortium-SGC, University of Campinas-UNICAMP, Campinas, SP, 13083-886, Brazil
| | - Mário Henrique Bengtson
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas-UNICAMP, Campinas, SP, 13083-970, Brazil. .,Center of Medicinal Chemistry-CQMED, Structural Genomics Consortium-SGC, University of Campinas-UNICAMP, Campinas, SP, 13083-886, Brazil.
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8
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Vargas JNS, Sleigh JN, Schiavo G. Coupling axonal mRNA transport and local translation to organelle maintenance and function. Curr Opin Cell Biol 2022; 74:97-103. [PMID: 35220080 PMCID: PMC10477965 DOI: 10.1016/j.ceb.2022.01.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/14/2022] [Accepted: 01/22/2022] [Indexed: 12/14/2022]
Abstract
Neuronal homeostasis requires the transport of various organelles to distal compartments and defects in this process lead to neurological disorders. Although several mechanisms for the delivery of organelles to axons and dendrites have been elucidated, exactly how this process is orchestrated is not well-understood. In this review, we discuss the recent literature supporting a novel paradigm - the co-shuttling of mRNAs with different membrane-bound organelles. This model postulates that the tethering of ribonucleoprotein complexes to endolysosomes and mitochondria allows for the spatiotemporal coupling of organelle transport and the delivery of transcripts to axons. Subcellular translation of these "hitchhiking" transcripts may thus provide a proximal source of proteins required for the maintenance and function of organelles in axons.
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Affiliation(s)
- Jose Norberto S Vargas
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK; UCL Queen Square Motor Neuron Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK; UK Dementia Research Institute, University College London, London, UK
| | - James N Sleigh
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK; UCL Queen Square Motor Neuron Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK; UK Dementia Research Institute, University College London, London, UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK; UCL Queen Square Motor Neuron Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK; UK Dementia Research Institute, University College London, London, UK.
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9
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Jablonka S, Hennlein L, Sendtner M. Therapy development for spinal muscular atrophy: perspectives for muscular dystrophies and neurodegenerative disorders. Neurol Res Pract 2022; 4:2. [PMID: 34983696 PMCID: PMC8725368 DOI: 10.1186/s42466-021-00162-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/21/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Major efforts have been made in the last decade to develop and improve therapies for proximal spinal muscular atrophy (SMA). The introduction of Nusinersen/Spinraza™ as an antisense oligonucleotide therapy, Onasemnogene abeparvovec/Zolgensma™ as an AAV9-based gene therapy and Risdiplam/Evrysdi™ as a small molecule modifier of pre-mRNA splicing have set new standards for interference with neurodegeneration. MAIN BODY Therapies for SMA are designed to interfere with the cellular basis of the disease by modifying pre-mRNA splicing and enhancing expression of the Survival Motor Neuron (SMN) protein, which is only expressed at low levels in this disorder. The corresponding strategies also can be applied to other disease mechanisms caused by loss of function or toxic gain of function mutations. The development of therapies for SMA was based on the use of cell culture systems and mouse models, as well as innovative clinical trials that included readouts that had originally been introduced and optimized in preclinical studies. This is summarized in the first part of this review. The second part discusses current developments and perspectives for amyotrophic lateral sclerosis, muscular dystrophies, Parkinson's and Alzheimer's disease, as well as the obstacles that need to be overcome to introduce RNA-based therapies and gene therapies for these disorders. CONCLUSION RNA-based therapies offer chances for therapy development of complex neurodegenerative disorders such as amyotrophic lateral sclerosis, muscular dystrophies, Parkinson's and Alzheimer's disease. The experiences made with these new drugs for SMA, and also the experiences in AAV gene therapies could help to broaden the spectrum of current approaches to interfere with pathophysiological mechanisms in neurodegeneration.
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Affiliation(s)
- Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital of Wuerzburg, Versbacher Str. 5, 97078, Wuerzburg, Germany.
| | - Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital of Wuerzburg, Versbacher Str. 5, 97078, Wuerzburg, Germany
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital of Wuerzburg, Versbacher Str. 5, 97078, Wuerzburg, Germany.
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10
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Ghanawi H, Hennlein L, Zare A, Bader J, Salehi S, Hornburg D, Ji C, Sivadasan R, Drepper C, Meissner F, Mann M, Jablonka S, Briese M, Sendtner M. Loss of full-length hnRNP R isoform impairs DNA damage response in motoneurons by inhibiting Yb1 recruitment to chromatin. Nucleic Acids Res 2021; 49:12284-12305. [PMID: 34850154 PMCID: PMC8643683 DOI: 10.1093/nar/gkab1120] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 10/20/2021] [Accepted: 10/28/2021] [Indexed: 01/13/2023] Open
Abstract
Neurons critically rely on the functions of RNA-binding proteins to maintain their polarity and resistance to neurotoxic stress. HnRNP R has a diverse range of post-transcriptional regulatory functions and is important for neuronal development by regulating axon growth. Hnrnpr pre-mRNA undergoes alternative splicing giving rise to a full-length protein and a shorter isoform lacking its N-terminal acidic domain. To investigate functions selectively associated with the full-length hnRNP R isoform, we generated a Hnrnpr knockout mouse (Hnrnprtm1a/tm1a) in which expression of full-length hnRNP R was abolished while production of the truncated hnRNP R isoform was retained. Motoneurons cultured from Hnrnprtm1a/tm1a mice did not show any axonal growth defects but exhibited enhanced accumulation of double-strand breaks and an impaired DNA damage response upon exposure to genotoxic agents. Proteomic analysis of the hnRNP R interactome revealed the multifunctional protein Yb1 as a top interactor. Yb1-depleted motoneurons were defective in DNA damage repair. We show that Yb1 is recruited to chromatin upon DNA damage where it interacts with γ-H2AX, a mechanism that is dependent on full-length hnRNP R. Our findings thus suggest a novel role of hnRNP R in maintaining genomic integrity and highlight the function of its N-terminal acidic domain in this context.
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Affiliation(s)
- Hanaa Ghanawi
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Abdolhossein Zare
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Jakob Bader
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried82152, Germany
| | - Saeede Salehi
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Daniel Hornburg
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Changhe Ji
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Rajeeve Sivadasan
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Carsten Drepper
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Felix Meissner
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried82152, Germany
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried82152, Germany
- NNF Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg 97080, Germany
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11
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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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12
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Nagano S, Araki T. Axonal Transport and Local Translation of mRNA in Neurodegenerative Diseases. Front Mol Neurosci 2021; 14:697973. [PMID: 34194300 PMCID: PMC8236635 DOI: 10.3389/fnmol.2021.697973] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/25/2021] [Indexed: 12/13/2022] Open
Abstract
Since neurons have long neurites including axons, it is crucial for the axons to transport many intracellular substances such as proteins and mitochondria in order to maintain their morphology and function. In addition, mRNAs have also been shown to be transported within axons. RNA-binding proteins form complexes with mRNAs, and regulate transport of the mRNAs to axons, as well as locally translate them into proteins. Local translation of mRNAs actively occurs during the development and damage of neurons, and plays an important role in axon elongation, regeneration, and synapse formation. In recent years, it has been reported that impaired axonal transport and local translation of mRNAs may be involved in the pathogenesis of some neurodegenerative diseases. In this review, we discuss the significance of mRNA axonal transport and their local translation in amyotrophic lateral sclerosis/frontotemporal dementia, spinal muscular atrophy, Alzheimer’s disease, and fragile X syndrome.
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Affiliation(s)
- Seiichi Nagano
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Osaka, Japan.,Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Toshiyuki Araki
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
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13
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Briese M, Sendtner M. Keeping the balance: The noncoding RNA 7SK as a master regulator for neuron development and function. Bioessays 2021; 43:e2100092. [PMID: 34050960 DOI: 10.1002/bies.202100092] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/11/2021] [Accepted: 05/18/2021] [Indexed: 12/18/2022]
Abstract
The noncoding RNA 7SK is a critical regulator of transcription by adjusting the activity of the kinase complex P-TEFb. Release of P-TEFb from 7SK stimulates transcription at many genes by promoting productive elongation. Conversely, P-TEFb sequestration by 7SK inhibits transcription. Recent studies have shown that 7SK functions are particularly important for neuron development and maintenance and it can thus be hypothesized that 7SK is at the center of many signaling pathways contributing to neuron function. 7SK activates neuronal gene expression programs that are key for terminal differentiation of neurons. Proteomics studies revealed a complex protein interactome of 7SK that includes several RNA-binding proteins. Some of these novel 7SK subcomplexes exert non-canonical cytosolic functions in neurons by regulating axonal mRNA transport and fine-tuning spliceosome production in response to transcription alterations. Thus, a picture emerges according to which 7SK acts as a multi-functional RNA scaffold that is integral for neuron homeostasis.
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Affiliation(s)
- Michael Briese
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
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14
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Dalla Costa I, Buchanan CN, Zdradzinski MD, Sahoo PK, Smith TP, Thames E, Kar AN, Twiss JL. The functional organization of axonal mRNA transport and translation. Nat Rev Neurosci 2021; 22:77-91. [PMID: 33288912 PMCID: PMC8161363 DOI: 10.1038/s41583-020-00407-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2020] [Indexed: 12/13/2022]
Abstract
Axons extend for tremendously long distances from the neuronal soma and make use of localized mRNA translation to rapidly respond to different extracellular stimuli and physiological states. The locally synthesized proteins support many different functions in both developing and mature axons, raising questions about the mechanisms by which local translation is organized to ensure the appropriate responses to specific stimuli. Publications over the past few years have uncovered new mechanisms for regulating the axonal transport and localized translation of mRNAs, with several of these pathways converging on the regulation of cohorts of functionally related mRNAs - known as RNA regulons - that drive axon growth, axon guidance, injury responses, axon survival and even axonal mitochondrial function. Recent advances point to these different regulatory pathways as organizing platforms that allow the axon's proteome to be modulated to meet its physiological needs.
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Affiliation(s)
- Irene Dalla Costa
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Courtney N Buchanan
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | | | - Pabitra K Sahoo
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Terika P Smith
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Elizabeth Thames
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Amar N Kar
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.
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15
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Congrains A, Niemann FS, Duarte ADSS, Ferro KPV, Olalla-Saad ST. Novel Non-Coding Transcript in NR4A3 Locus, LncNR4A3, Regulates RNA Processing Machinery Proteins and NR4A3 Expression. Front Oncol 2020; 10:569668. [PMID: 33330042 PMCID: PMC7719789 DOI: 10.3389/fonc.2020.569668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022] Open
Abstract
NR4A3 is a key tumor suppressor in myeloid malignancy, mice lacking both NR4A1 and family member NR4A3 rapidly develop lethal acute myeloid leukemia (AML). We identified a long non-coding transcript in the NR4A3 locus and pursued the characterization of this anonymous transcript and the study of its role in leukemogenesis. We characterized this novel long non-coding transcript as a sense polyadenylated transcript. Bone marrow cells from AML patients expressed significantly reduced levels of lncNR4A3 compared to healthy controls (controls = 15, MDS= 20, p=0.05., AML= 21, p<0.01). Expression of NR4A3, as previously reported, was also significantly reduced in AML. Interestingly, the expression of both coding and non-coding transcripts was highly correlated (Pearson R = 0.3771, P<0.01). Transient over-expression of LncNR4A3 by nucleofection led to an increase in the RNA and protein level of NR4A3, reduction of proliferation in myeloid cell lines K-562 and KG1 (n=3 and 2 respectively, p<0.05) and reduced colony formation capacity in primary leukemic cells. A mass spectrometry-based quantitative proteomics approach was used to identify proteins dysregulated after lncNR4A3 over-expression in K-562. Enrichment analysis showed that the altered proteins are biologically connected (n=4, p<0.001) and functionally associated to RNA binding, transcription elongation, and splicing. Remarkably, we were able to validate the most significant results by WB. We showed that this novel transcript, lncNR4A3 regulates NR4A3 and we hypothesize this regulatory mechanism is mediated by the modulation of the RNA processing machinery.
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Affiliation(s)
- Ada Congrains
- Hematology and Transfusion Medicine Center, University of Campinas, Campinas, Brazil
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16
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Vanslembrouck B, Ampe C, Hengel J. Time for rethinking the different β‐actin transgenic mouse models? Cytoskeleton (Hoboken) 2020; 77:527-543. [DOI: 10.1002/cm.21647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 11/19/2020] [Accepted: 11/24/2020] [Indexed: 01/23/2023]
Affiliation(s)
- Bieke Vanslembrouck
- Medical Cell Biology Research Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences Ghent University Ghent Belgium
| | - Christophe Ampe
- Department of Biomolecular Medicine, Faculty of Medicine and Health Sciences Ghent University Ghent Belgium
| | - Jolanda Hengel
- Medical Cell Biology Research Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences Ghent University Ghent Belgium
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17
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Weghorst F, Mirzakhanyan Y, Samimi K, Dhillon M, Barzik M, Cunningham LL, Gershon PD, Cramer KS. Caspase-3 Cleaves Extracellular Vesicle Proteins During Auditory Brainstem Development. Front Cell Neurosci 2020; 14:573345. [PMID: 33281555 PMCID: PMC7689216 DOI: 10.3389/fncel.2020.573345] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 10/05/2020] [Indexed: 12/26/2022] Open
Abstract
Sound localization requires extremely precise development of auditory brainstem circuits, the molecular mechanisms of which are largely unknown. We previously demonstrated a novel requirement for non-apoptotic activity of the protease caspase-3 in chick auditory brainstem development. Here, we used mass spectrometry to identify proteolytic substrates of caspase-3 during chick auditory brainstem development. These auditory brainstem caspase-3 substrates were enriched for proteins previously shown to be cleaved by caspase-3, especially in non-apoptotic contexts. Functional annotation analysis revealed that our caspase-3 substrates were also enriched for proteins associated with several protein categories, including proteins found in extracellular vesicles (EVs), membrane-bound nanoparticles that function in intercellular communication. The proteome of EVs isolated from the auditory brainstem was highly enriched for our caspase-3 substrates. Additionally, we identified two caspase-3 substrates with known functions in axon guidance, namely Neural Cell Adhesion Molecule (NCAM) and Neuronal-glial Cell Adhesion Molecule (Ng-CAM), that were found in auditory brainstem EVs and expressed in the auditory pathway alongside cleaved caspase-3. Taken together, these data suggest a novel developmental mechanism whereby caspase-3 influences auditory brainstem circuit formation through the proteolytic cleavage of extracellular vesicle (EV) proteins.
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Affiliation(s)
- Forrest Weghorst
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Yeva Mirzakhanyan
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States
| | - Kian Samimi
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Mehron Dhillon
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Melanie Barzik
- Section on Sensory Cell Biology, NIDCD, NIH, Bethesda, MD, United States
| | - Lisa L. Cunningham
- Section on Sensory Cell Biology, NIDCD, NIH, Bethesda, MD, United States
| | - Paul D. Gershon
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States
| | - Karina S. Cramer
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
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18
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Oliveira NCM, Lins ÉM, Massirer KB, Bengtson MH. Translational Control during Mammalian Neocortex Development and Postembryonic Neuronal Function. Semin Cell Dev Biol 2020; 114:36-46. [PMID: 33020045 DOI: 10.1016/j.semcdb.2020.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 09/09/2020] [Accepted: 09/09/2020] [Indexed: 12/21/2022]
Abstract
The control of mRNA translation has key roles in the regulation of gene expression and biological processes such as mammalian cellular differentiation and identity. Methodological advances in the last decade have resulted in considerable progress towards understanding how translational control contributes to the regulation of diverse biological phenomena. In this review, we discuss recent findings in the involvement of translational control in the mammalian neocortex development and neuronal biology. We focus on regulatory mechanisms that modulate translational efficiency during neural stem cells self-renewal and differentiation, as well as in neuronal-related processes such as synapse, plasticity, and memory.
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Affiliation(s)
- Natássia Cristina Martins Oliveira
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas - UNICAMP, 13083-862, Campinas, SP, Brazil; Center for Molecular Biology and Genetic Engineering - CBMEG, University of Campinas - UNICAMP, 13083-875, Campinas, SP, Brazil; Center of Medicinal Chemistry - CQMED, Structural Genomics Consortium - SGC, University of Campinas - UNICAMP, 13083-886, Campinas, SP, Brazil
| | - Érico Moreto Lins
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas - UNICAMP, 13083-862, Campinas, SP, Brazil; PhD Program in Genetics and Molecular Biology (PGBM), UNICAMP, Campinas, SP 13083-862, Brazil
| | - Katlin Brauer Massirer
- Center for Molecular Biology and Genetic Engineering - CBMEG, University of Campinas - UNICAMP, 13083-875, Campinas, SP, Brazil; Center of Medicinal Chemistry - CQMED, Structural Genomics Consortium - SGC, University of Campinas - UNICAMP, 13083-886, Campinas, SP, Brazil
| | - Mário Henrique Bengtson
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas - UNICAMP, 13083-862, Campinas, SP, Brazil; Center of Medicinal Chemistry - CQMED, Structural Genomics Consortium - SGC, University of Campinas - UNICAMP, 13083-886, Campinas, SP, Brazil.
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19
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Low YH, Asi Y, Foti SC, Lashley T. Heterogeneous Nuclear Ribonucleoproteins: Implications in Neurological Diseases. Mol Neurobiol 2020; 58:631-646. [PMID: 33000450 PMCID: PMC7843550 DOI: 10.1007/s12035-020-02137-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/17/2020] [Indexed: 12/13/2022]
Abstract
Heterogenous nuclear ribonucleoproteins (hnRNPs) are a complex and functionally diverse family of RNA binding proteins with multifarious roles. They are involved, directly or indirectly, in alternative splicing, transcriptional and translational regulation, stress granule formation, cell cycle regulation, and axonal transport. It is unsurprising, given their heavy involvement in maintaining functional integrity of the cell, that their dysfunction has neurological implications. However, compared to their more established roles in cancer, the evidence of hnRNP implication in neurological diseases is still in its infancy. This review aims to consolidate the evidences for hnRNP involvement in neurological diseases, with a focus on spinal muscular atrophy (SMA), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), multiple sclerosis (MS), congenital myasthenic syndrome (CMS), and fragile X-associated tremor/ataxia syndrome (FXTAS). Understanding more about hnRNP involvement in neurological diseases can further elucidate the pathomechanisms involved in these diseases and perhaps guide future therapeutic advances.
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Affiliation(s)
- Yi-Hua Low
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,Duke-NUS Medical School, Singapore, Singapore
| | - Yasmine Asi
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Sandrine C Foti
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Tammaryn Lashley
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. .,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK.
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20
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Abstract
It is increasingly recognized that local protein synthesis (LPS) contributes to fundamental aspects of axon biology, in both developing and mature neurons. Mutations in RNA-binding proteins (RBPs), as central players in LPS, and other proteins affecting RNA localization and translation are associated with a range of neurological disorders, suggesting disruption of LPS may be of pathological significance. In this review, we substantiate this hypothesis by examining the link between LPS and key axonal processes, and the implicated pathophysiological consequences of dysregulated LPS. First, we describe how the length and autonomy of axons result in an exceptional reliance on LPS. We next discuss the roles of LPS in maintaining axonal structural and functional polarity and axonal trafficking. We then consider how LPS facilitates the establishment of neuronal connectivity through regulation of axonal branching and pruning, how it mediates axonal survival into adulthood and its involvement in neuronal stress responses.
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Affiliation(s)
- Julie Qiaojin Lin
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Island Research Building, Cambridge Biomedical Campus, Cambridge, UK
| | | | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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21
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Turner-Bridger B, Caterino C, Cioni JM. Molecular mechanisms behind mRNA localization in axons. Open Biol 2020; 10:200177. [PMID: 32961072 PMCID: PMC7536069 DOI: 10.1098/rsob.200177] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/01/2020] [Indexed: 12/12/2022] Open
Abstract
Messenger RNA (mRNA) localization allows spatiotemporal regulation of the proteome at the subcellular level. This is observed in the axons of neurons, where mRNA localization is involved in regulating neuronal development and function by orchestrating rapid adaptive responses to extracellular cues and the maintenance of axonal homeostasis through local translation. Here, we provide an overview of the key findings that have broadened our knowledge regarding how specific mRNAs are trafficked and localize to axons. In particular, we review transcriptomic studies investigating mRNA content in axons and the molecular principles underpinning how these mRNAs arrived there, including cis-acting mRNA sequences and trans-acting proteins playing a role. Further, we discuss evidence that links defective axonal mRNA localization and pathological outcomes.
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Affiliation(s)
- Benita Turner-Bridger
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, UK
| | - Cinzia Caterino
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | - Jean-Michel Cioni
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
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22
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Smith TP, Sahoo PK, Kar AN, Twiss JL. Intra-axonal mechanisms driving axon regeneration. Brain Res 2020; 1740:146864. [PMID: 32360100 DOI: 10.1016/j.brainres.2020.146864] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/27/2022]
Abstract
Traumatic injury to the peripheral and central nervous systems very often causes axotomy, where an axon loses connections with its target resulting in loss of function. The axon segments distal to the injury site lose connection with the cell body and degenerate. Axotomized neurons in the periphery can spontaneously mount a regenerative response and reconnect to their denervated target tissues, though this is rarely complete in humans. In contrast, spontaneous regeneration rarely occurs after axotomy in the spinal cord and brain. Here, we concentrate on the mechanisms underlying this spontaneous regeneration in the peripheral nervous system, focusing on events initiated from the axon that support regenerative growth. We contrast this with what is known for axonal injury responses in the central nervous system. Considering the neuropathy focus of this special issue, we further draw parallels and distinctions between the injury-response mechanisms that initiate regenerative gene expression programs and those that are known to trigger axon degeneration.
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Affiliation(s)
- Terika P Smith
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Pabitra K Sahoo
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Amar N Kar
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.
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23
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Chung HW, Weng JC, King CE, Chuang CF, Chow WY, Chang YC. BDNF elevates the axonal levels of hnRNPs Q and R in cultured rat cortical neurons. Mol Cell Neurosci 2019; 98:97-108. [PMID: 31202892 DOI: 10.1016/j.mcn.2019.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 05/08/2019] [Accepted: 06/12/2019] [Indexed: 11/17/2022] Open
Abstract
Local translation plays important roles in the maintenance and various functions of axons, and dysfunctions of local translation in axons are implicated in various neurological diseases. Heterogeneous nuclear ribonucleoproteins (hnRNPs) are RNA binding proteins with multiple functions in RNA metabolism. Here, we identified 20 hnRNPs in the axons of cultured rat cortical neurons by interrogating published axon mass spectrometric databases with rat protein databases. Among those identified in axons are highly related hnRNPs Q and R. RT-PCR analysis indicated that axons also contained low levels of hnRNPs Q and R mRNAs. We further found that BDNF treatments raised the levels of hnRNPs Q and R proteins in whole neurons and axons. BDNF also increased the level of poly(A) RNA as well as the proportion of poly(A) RNA granules containing hnRNPs Q and R in the axon. However, following severing the connection between the cell bodies and axons, BDNF did not affect the levels of hnRNPs Q and R, the content of poly(A) RNA, or the colocalization of poly(A) RNA and hnRNPs Q and R in the axon any more, although BDNF still stimulated the local translation in severed axons as it did in intact axons. The results are consistent with that BDNF enhances the axonal transport of RNA granules. The results further suggest that hnRNPs Q and R play a role in the mechanism underlying the enhancement of axonal RNA transport by BDNF.
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Affiliation(s)
- Hui-Wen Chung
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan.
| | - Ju-Chen Weng
- Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu, Taiwan
| | - Chih-En King
- Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu, Taiwan
| | - Chih-Fan Chuang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan.
| | - Wei-Yuan Chow
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan.
| | - Yen-Chung Chang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan; Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu, Taiwan.
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24
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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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25
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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: 44] [Impact Index Per Article: 7.3] [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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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: 39] [Impact Index Per Article: 6.5] [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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27
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Lee SJ, Oses-Prieto JA, Kawaguchi R, Sahoo PK, Kar AN, Rozenbaum M, Oliver D, Chand S, Ji H, Shtutman M, Miller-Randolph S, Taylor RJ, Fainzilber M, Coppola G, Burlingame AL, Twiss JL. hnRNPs Interacting with mRNA Localization Motifs Define Axonal RNA Regulons. Mol Cell Proteomics 2018; 17:2091-2106. [PMID: 30038033 DOI: 10.1074/mcp.ra118.000603] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 07/05/2018] [Indexed: 12/30/2022] Open
Abstract
mRNA translation in axons enables neurons to introduce new proteins at sites distant from their cell body. mRNA-protein interactions drive this post-transcriptional regulation, yet knowledge of RNA binding proteins (RBP) in axons is limited. Here we used proteomics to identify RBPs interacting with the axonal localizing motifs of Nrn1, Hmgb1, Actb, and Gap43 mRNAs, revealing many novel RBPs in axons. Interestingly, no RBP is shared between all four RNA motifs, suggesting graded and overlapping specificities of RBP-mRNA pairings. A systematic assessment of axonal mRNAs interacting with hnRNP H1, hnRNP F, and hnRNP K, proteins that bound with high specificity to Nrn1 and Hmgb1, revealed that axonal mRNAs segregate into axon growth-associated RNA regulons based on hnRNP interactions. Axotomy increases axonal transport of hnRNPs H1, F, and K, depletion of these hnRNPs decreases axon growth and reduces axonal mRNA levels and axonal protein synthesis. Thus, subcellular hnRNP-interacting RNA regulons support neuronal growth and regeneration.
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Affiliation(s)
- Seung Joon Lee
- From the ‡Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208
| | - Juan A Oses-Prieto
- §Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158
| | - Riki Kawaguchi
- ¶Department of Psychiatry and Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
| | - Pabitra K Sahoo
- From the ‡Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208
| | - Amar N Kar
- From the ‡Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208
| | - Meir Rozenbaum
- ‖Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - David Oliver
- **Department of Drug Discovery and Biomedical Sciences, University of South Carolina, Columbia, SC, 29208
| | - Shreya Chand
- §Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158
| | - Hao Ji
- **Department of Drug Discovery and Biomedical Sciences, University of South Carolina, Columbia, SC, 29208
| | - Michael Shtutman
- **Department of Drug Discovery and Biomedical Sciences, University of South Carolina, Columbia, SC, 29208
| | | | - Ross J Taylor
- From the ‡Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208
| | - Mike Fainzilber
- ‖Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Giovanni Coppola
- ¶Department of Psychiatry and Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095.,‡‡Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095
| | - Alma L Burlingame
- §Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158
| | - Jeffery L Twiss
- From the ‡Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208;
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Sahoo PK, Smith DS, Perrone-Bizzozero N, Twiss JL. Axonal mRNA transport and translation at a glance. J Cell Sci 2018; 131:jcs196808. [PMID: 29654160 PMCID: PMC6518334 DOI: 10.1242/jcs.196808] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Localization and translation of mRNAs within different subcellular domains provides an important mechanism to spatially and temporally introduce new proteins in polarized cells. Neurons make use of this localized protein synthesis during initial growth, regeneration and functional maintenance of their axons. Although the first evidence for protein synthesis in axons dates back to 1960s, improved methodologies, including the ability to isolate axons to purity, highly sensitive RNA detection methods and imaging approaches, have shed new light on the complexity of the transcriptome of the axon and how it is regulated. Moreover, these efforts are now uncovering new roles for locally synthesized proteins in neurological diseases and injury responses. In this Cell Science at a Glance article and the accompanying poster, we provide an overview of how axonal mRNA transport and translation are regulated, and discuss their emerging links to neurological disorders and neural repair.
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Affiliation(s)
- Pabitra K Sahoo
- Department of Biological Sciences, University of South Carolina, 715 Sumter St., CLS 401, Columbia, SC 29208, USA
| | - Deanna S Smith
- Department of Biological Sciences, University of South Carolina, 715 Sumter St., CLS 401, Columbia, SC 29208, USA
| | - Nora Perrone-Bizzozero
- Department of Neurosciences, University of New Mexico School of Medicine, 1 University of New Mexico, MSC08 4740, Albuquerque, NM 87131, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, 715 Sumter St., CLS 401, Columbia, SC 29208, USA
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Age-dependent neurodegeneration and organelle transport deficiencies in mutant TDP43 patient-derived neurons are independent of TDP43 aggregation. Neurobiol Dis 2018; 115:167-181. [PMID: 29630989 DOI: 10.1016/j.nbd.2018.03.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/27/2018] [Accepted: 03/23/2018] [Indexed: 01/07/2023] Open
Abstract
TAR DNA-binding protein 43 (TDP43) plays a significant role in familiar and sporadic amyotrophic lateral sclerosis (ALS). The diverse postulated mechanisms by which TDP43 mutations cause the disease are not fully understood. Human wildtype and TDP43 S393L and G294V mutant spinal motor neuron cultures were differentiated from patient-derived iPSCs. Mutant hTDP43 and wildtype motor neuron cultures did not differ in neuron differentiation capacity during early maturation stage. During aging we detected a dramatic neurodegeneration including neuron loss and pathological neurofilament abnormalities only in TDP43 mutant cultures. Additionally mitochondria and lysosomes of aging spinal motor neurons revealed robust TDP43 mutation dependent abnormal phenotypes in size, shape, speed and motility which all appeared without TDP43 mislocalization or aggregation formation. Furthermore, D-sorbitol - known to induce stress granules and cytoplasmic mislocalization of TDP43 - rescued axonal trafficking phenotypes without signs of TDP43 mislocalization or aggregation formation. Our data indicate TDP43 mutation-dependent but cytosolic aggregation-independent mechanisms of motor neuron degeneration in TDP43 ALS.
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hnRNP R and its main interactor, the noncoding RNA 7SK, coregulate the axonal transcriptome of motoneurons. Proc Natl Acad Sci U S A 2018; 115:E2859-E2868. [PMID: 29507242 PMCID: PMC5866599 DOI: 10.1073/pnas.1721670115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Neurons are highly polarized cells. RNA-binding proteins contribute to this polarization by generating diverse subcellular transcriptomes. The RNA-binding protein hnRNP R is essential for axon growth in motoneurons. This study reports the RNA interactome for hnRNP R. The main interacting RNA of hnRNP R was the noncoding RNA 7SK. Depletion of 7SK from primary motoneurons disturbed axon growth. This effect was dependent on the interaction of 7SK with hnRNP R. Both hnRNP R and 7SK localize to axons. Loss of 7SK led to a similar depletion of axonal transcripts as loss of hnRNP R. Our data suggest that 7SK, in addition to its role in transcriptional regulation, acts in concert with hnRNP R to sort specific transcripts into axons. Disturbed RNA processing and subcellular transport contribute to the pathomechanisms of motoneuron diseases such as amyotrophic lateral sclerosis and spinal muscular atrophy. RNA-binding proteins are involved in these processes, but the mechanisms by which they regulate the subcellular diversity of transcriptomes, particularly in axons, are not understood. Heterogeneous nuclear ribonucleoprotein R (hnRNP R) interacts with several proteins involved in motoneuron diseases. It is located in axons of developing motoneurons, and its depletion causes defects in axon growth. Here, we used individual nucleotide-resolution cross-linking and immunoprecipitation (iCLIP) to determine the RNA interactome of hnRNP R in motoneurons. We identified ∼3,500 RNA targets, predominantly with functions in synaptic transmission and axon guidance. Among the RNA targets identified by iCLIP, the noncoding RNA 7SK was the top interactor of hnRNP R. We detected 7SK in the nucleus and also in the cytosol of motoneurons. In axons, 7SK localized in close proximity to hnRNP R, and depletion of hnRNP R reduced axonal 7SK. Furthermore, suppression of 7SK led to defective axon growth that was accompanied by axonal transcriptome alterations similar to those caused by hnRNP R depletion. Using a series of 7SK-deletion mutants, we show that the function of 7SK in axon elongation depends on its interaction with hnRNP R but not with the PTEF-B complex involved in transcriptional regulation. These results propose a role for 7SK as an essential interactor of hnRNP R to regulate its function in axon maintenance.
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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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O'Meara RW, Cummings SE, De Repentigny Y, McFall E, Michalski JP, Deguise MO, Gibeault S, Kothary R. Oligodendrocyte development and CNS myelination are unaffected in a mouse model of severe spinal muscular atrophy. Hum Mol Genet 2017; 26:282-292. [PMID: 28069797 DOI: 10.1093/hmg/ddw385] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 11/04/2016] [Indexed: 11/12/2022] Open
Abstract
The childhood neurodegenerative disease spinal muscular atrophy (SMA) is caused by loss-of-function mutations or deletions in the Survival Motor Neuron 1 (SMN1) gene resulting in insufficient levels of survival motor neuron (SMN) protein. Classically considered a motor neuron disease, increasing evidence now supports SMA as a multi-system disorder with phenotypes discovered in cortical neuron, astrocyte, and Schwann cell function within the nervous system. In this study, we sought to determine whether Smn was critical for oligodendrocyte (OL) development and central nervous system myelination. A mouse model of severe SMA was used to assess OL growth, migration, differentiation and myelination. All aspects of OL development and function studied were unaffected by Smn depletion. The tremendous impact of Smn depletion on a wide variety of other cell types renders the OL response unique. Further investigation of the OLs derived from SMA models may reveal disease modifiers or a compensatory mechanism allowing these cells to flourish despite the reduced levels of this multifunctional protein.
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Affiliation(s)
- Ryan W O'Meara
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Sarah E Cummings
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Yves De Repentigny
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Emily McFall
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - John-Paul Michalski
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Marc-Olivier Deguise
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Sabrina Gibeault
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Rashmi Kothary
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada.,Department of Medicine, University of Ottawa, Ottawa, ON, Canada
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33
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Hosseinibarkooie S, Schneider S, Wirth B. Advances in understanding the role of disease-associated proteins in spinal muscular atrophy. Expert Rev Proteomics 2017. [PMID: 28635376 DOI: 10.1080/14789450.2017.1345631] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Spinal muscular atrophy (SMA) is a neurodegenerative disorder characterized by alpha motor neuron loss in the spinal cord due to reduced survival motor neuron (SMN) protein level. While the genetic basis of SMA is well described, the specific molecular pathway underlying SMA is still not fully understood. Areas covered: This review discusses the recent advancements in understanding the molecular pathways in SMA using different omics approaches and genetic modifiers identified in both vertebrate and invertebrate systems. The findings that are summarized in this article were deduced from original articles and reviews with a particular focus on the latest advancements in the field. Expert commentary: The identification of genetic modifiers such as PLS3 and NCALD in humans or of SMA modulators such as Elavl4 (HuD), Copa, Uba1, Mapk10 (Jnk3), Nrxn2 and Tmem41b (Stasimon) in various SMA animal models improved our knowledge of impaired cellular pathways in SMA. Inspiration from modifier genes and their functions in motor neuron and neuromuscular junctions may open a new avenue for future SMA combinatorial therapies.
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Affiliation(s)
- Seyyedmohsen Hosseinibarkooie
- a Institute of Human Genetics , University of Cologne , Cologne , Germany.,b Center for Molecular Medicine Cologne , University of Cologne , Cologne , Germany.,c Institute for Genetics , University of Cologne , Cologne , Germany
| | - Svenja Schneider
- a Institute of Human Genetics , University of Cologne , Cologne , Germany.,b Center for Molecular Medicine Cologne , University of Cologne , Cologne , Germany.,c Institute for Genetics , University of Cologne , Cologne , Germany
| | - Brunhilde Wirth
- a Institute of Human Genetics , University of Cologne , Cologne , Germany.,b Center for Molecular Medicine Cologne , University of Cologne , Cologne , Germany.,c Institute for Genetics , University of Cologne , Cologne , Germany.,d Center for Rare Diseases Cologne , University Hospital of Cologne, University of Cologne , Cologne , Germany
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Kar AN, Lee SJ, Twiss JL. Expanding Axonal Transcriptome Brings New Functions for Axonally Synthesized Proteins in Health and Disease. Neuroscientist 2017; 24:111-129. [PMID: 28593814 DOI: 10.1177/1073858417712668] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intra-axonal protein synthesis has been shown to play critical roles in both development and repair of axons. Axons provide long-range connectivity in the nervous system, and disruption of their function and/or structure is seen in several neurological diseases and disorders. Axonally synthesized proteins or losses in axonally synthesized proteins contribute to neurodegenerative diseases, neuropathic pain, viral transport, and survival of axons. Increasing sensitivity of RNA detection and quantitation coupled with methods to isolate axons to purity has shown that a surprisingly complex transcriptome exists in axons. This extends across different species, neuronal populations, and physiological conditions. These studies have helped define the repertoire of neuronal mRNAs that can localize into axons and imply previously unrecognized functions for local translation in neurons. Here, we review the current state of transcriptomics studies of isolated axons, contrast axonal mRNA profiles between different neuronal types and growth states, and discuss how mRNA transport into and translation within axons contribute to neurological disorders.
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Affiliation(s)
- Amar N Kar
- 1 Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Seung Joon Lee
- 1 Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jeffery L Twiss
- 1 Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.,2 Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
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35
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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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36
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Tu WY, Simpson JE, Highley JR, Heath PR. Spinal muscular atrophy: Factors that modulate motor neurone vulnerability. Neurobiol Dis 2017; 102:11-20. [PMID: 28161391 DOI: 10.1016/j.nbd.2017.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/10/2017] [Accepted: 01/31/2017] [Indexed: 01/07/2023] Open
Abstract
Spinal muscular atrophy (SMA), a leading genetic cause of infant death, is a neurodegenerative disease characterised by the selective loss of particular groups of motor neurones in the anterior horn of the spinal cord with concomitant muscle weakness. To date, no effective treatment is available, however, there are ongoing clinical trials are in place which promise much for the future. However, there remains an ongoing problem in trying to link a single gene loss to motor neurone degeneration. Fortunately, given successful disease models that have been established and intensive studies on SMN functions in the past ten years, we are fast approaching the stage of identifying the underlying mechanisms of SMA pathogenesis Here we discuss potential disease modifying factors on motor neurone vulnerability, in the belief that these factors give insight into the pathological mechanisms of SMA and therefore possible therapeutic targets.
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Affiliation(s)
- Wen-Yo Tu
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Julie E Simpson
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - J Robin Highley
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Paul R Heath
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK.
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Hermes Regulates Axon Sorting in the Optic Tract by Post-Trancriptional Regulation of Neuropilin 1. J Neurosci 2016; 36:12697-12706. [PMID: 27974617 PMCID: PMC5157111 DOI: 10.1523/jneurosci.2400-16.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/27/2016] [Accepted: 09/30/2016] [Indexed: 01/31/2023] Open
Abstract
The establishment of precise topographic maps during neural development is facilitated by the presorting of axons in the pathway before they reach their targets. In the vertebrate visual system, such topography is seen clearly in the optic tract (OT) and in the optic radiations. However, the molecular mechanisms involved in pretarget axon sorting are poorly understood. Here, we show in zebrafish that the RNA-binding protein Hermes, which is expressed exclusively in retinal ganglion cells (RGCs), is involved in this process. Using a RiboTag approach, we show that Hermes acts as a negative translational regulator of specific mRNAs in RGCs. One of these targets is the guidance cue receptor Neuropilin 1 (Nrp1), which is sensitive to the repellent cue Semaphorin 3A (Sema3A). Hermes knock-down leads to topographic missorting in the OT through the upregulation of Nrp1. Restoring Nrp1 to appropriate levels in Hermes-depleted embryos rescues this effect and corrects the axon-sorting defect in the OT. Our data indicate that axon sorting relies on Hermes-regulated translation of Nrp1. SIGNIFICANCE STATEMENT An important mechanism governing the formation of the mature neural map is pretarget axon sorting within the sensory tract; however, the molecular mechanisms involved in this process remain largely unknown. The work presented here reveals a novel function for the RNA-binding protein Hermes in regulating the topographic sorting of retinal ganglion cell (RGC) axons in the optic tract and tectum. We find that Hermes negatively controls the translation of the guidance cue receptor Neuropilin-1 in RGCs, with Hermes knock-down resulting in aberrant growth cone cue sensitivity and axonal topographic misprojections. We characterize a novel RNA-based mechanism by which axons restrict their translatome developmentally to achieve proper targeting.
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38
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Schoen M, Reichel JM, Demestre M, Putz S, Deshpande D, Proepper C, Liebau S, Schmeisser MJ, Ludolph AC, Michaelis J, Boeckers TM. Super-Resolution Microscopy Reveals Presynaptic Localization of the ALS/FTD Related Protein FUS in Hippocampal Neurons. Front Cell Neurosci 2016; 9:496. [PMID: 26834559 PMCID: PMC4709451 DOI: 10.3389/fncel.2015.00496] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/09/2015] [Indexed: 12/12/2022] Open
Abstract
Fused in Sarcoma (FUS) is a multifunctional RNA-/DNA-binding protein, which is involved in the pathogenesis of the neurodegenerative disorders amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A common hallmark of these disorders is the abnormal accumulation of mutated FUS protein in the cytoplasm. Under normal conditions FUS is confined to the nuclear compartment, in neurons, however, additional somatodendritic localization can be observed. In this study, we carefully analyzed the subcellular localization of endogenous FUS at synaptic sites of hippocampal neurons which are among the most affected cell types in FTD with FUS pathology. We could confirm a strong nuclear localization of FUS as well as its prominent and widespread neuronal expression throughout the adult and developing rat brain, particularly in the hippocampus, the cerebellum and the outer layers of the cortex. Intriguingly, FUS was also consistently observed at synaptic sites as detected by neuronal subcellular fractionation as well as by immunolabeling. To define a pre- and/or postsynaptic localization of FUS, we employed super-resolution fluorescence localization microscopy. FUS was found to be localized within the axon terminal in close proximity to the presynaptic vesicle protein Synaptophysin1 and adjacent to the active zone protein Bassoon, but well separated from the postsynaptic protein PSD-95. Having shown the presynaptic localization of FUS in the nervous system, a novel extranuclear role of FUS at neuronal contact sites has to be considered. Since there is growing evidence that local presynaptic translation might also be an important mechanism for plasticity, FUS - like the fragile X mental retardation protein FMRP - might act as one of the presynaptic RNA-binding proteins regulating this machinery. Our observation of presynaptic FUS should foster further investigations to determine its role in neurodegenerative diseases such as ALS and FTD.
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Affiliation(s)
- Michael Schoen
- Institute for Anatomy and Cell Biology, Ulm University Ulm, Germany
| | | | - Maria Demestre
- Institute for Anatomy and Cell Biology, Ulm University Ulm, Germany
| | - Stefan Putz
- Institute for Anatomy and Cell Biology, Ulm UniversityUlm, Germany; Department of Neurology, Ulm UniversityUlm, Germany
| | | | | | - Stefan Liebau
- Institute of Neuroanatomy, Eberhard Karls University Tübingen Tübingen, Germany
| | - Michael J Schmeisser
- Institute for Anatomy and Cell Biology, Ulm UniversityUlm, Germany; Department of Neurology, Ulm UniversityUlm, Germany
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Gabanella F, Pisani C, Borreca A, Farioli-Vecchioli S, Ciotti MT, Ingegnere T, Onori A, Ammassari-Teule M, Corbi N, Canu N, Monaco L, Passananti C, Di Certo MG. SMN affects membrane remodelling and anchoring of the protein synthesis machinery. J Cell Sci 2016; 129:804-16. [PMID: 26743087 DOI: 10.1242/jcs.176750] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/29/2015] [Indexed: 12/31/2022] Open
Abstract
Disconnection between membrane signalling and actin networks can have catastrophic effects depending on cell size and polarity. The survival motor neuron (SMN) protein is ubiquitously involved in assembly of spliceosomal small nuclear ribonucleoprotein particles. Other SMN functions could, however, affect cellular activities driving asymmetrical cell surface expansions. Genes able to mitigate SMN deficiency operate within pathways in which SMN can act, such as mRNA translation, actin network and endocytosis. Here, we found that SMN accumulates at membrane protrusions during the dynamic rearrangement of the actin filaments. In addition to localization data, we show that SMN interacts with caveolin-1, which mediates anchoring of translation machinery components. Importantly, SMN deficiency depletes the plasma membrane of ribosomes, and this correlates with the failure of fibroblasts to extend membrane protrusions. These findings strongly support a relationship between SMN and membrane dynamics. We propose that SMN could assembly translational platforms associated with and governed by the plasma membrane. This activity could be crucial in cells that have an exacerbated interdependence of membrane remodelling and local protein synthesis.
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Affiliation(s)
- Francesca Gabanella
- CNR-Institute of Cell Biology and Neurobiology, Rome 00143, Italy IRCCS Fondazione Santa Lucia, Rome 00143, Italy
| | - Cinzia Pisani
- CNR-IBPM, Department of Molecular Medicine, Sapienza University of Rome, Rome 00161, Italy
| | - Antonella Borreca
- CNR-Institute of Cell Biology and Neurobiology, Rome 00143, Italy IRCCS Fondazione Santa Lucia, Rome 00143, Italy
| | - Stefano Farioli-Vecchioli
- CNR-Institute of Cell Biology and Neurobiology, Rome 00143, Italy IRCCS Fondazione Santa Lucia, Rome 00143, Italy
| | - Maria Teresa Ciotti
- CNR-Institute of Cell Biology and Neurobiology, Rome 00143, Italy European Brain Research Institute (EBRI) Rita Levi-Montalcini, Rome 00143, Italy
| | - Tiziano Ingegnere
- Department of Ecological and Biological Sciences, Tuscia University, Viterbo 01100, Italy
| | - Annalisa Onori
- CNR-IBPM, Department of Molecular Medicine, Sapienza University of Rome, Rome 00161, Italy
| | - Martine Ammassari-Teule
- CNR-Institute of Cell Biology and Neurobiology, Rome 00143, Italy IRCCS Fondazione Santa Lucia, Rome 00143, Italy
| | - Nicoletta Corbi
- CNR-IBPM, Department of Molecular Medicine, Sapienza University of Rome, Rome 00161, Italy
| | - Nadia Canu
- CNR-Institute of Cell Biology and Neurobiology, Rome 00143, Italy Department of System Medicine, University of 'Tor Vergata', Rome 00137, Italy
| | - Lucia Monaco
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome 00185, Italy
| | - Claudio Passananti
- CNR-IBPM, Department of Molecular Medicine, Sapienza University of Rome, Rome 00161, Italy
| | - Maria Grazia Di Certo
- CNR-Institute of Cell Biology and Neurobiology, Rome 00143, Italy IRCCS Fondazione Santa Lucia, Rome 00143, Italy
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40
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Lee HR, Kim TD, Kim HJ, Jung Y, Lee D, Lee KH, Kim DY, Woo KC, Kim KT. Heterogeneous ribonucleoprotein R regulates arylalkylamine N-acetyltransferase synthesis via internal ribosomal entry site-mediated translation in a circadian manner. J Pineal Res 2015; 59:518-29. [PMID: 26444903 DOI: 10.1111/jpi.12284] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 10/02/2015] [Indexed: 01/07/2023]
Abstract
Rhythmic arylalkylamine N-acetyltransferase (AANAT) synthesis is a prominent circadian-controlled response that occurs in most mammals. AANAT is the core enzyme in melatonin production; because melatonin participates in many physiological processes, the regulation of AANAT is an important research topic. In this study, we focused on the role of heterogeneous ribonucleoprotein R (hnRNP R) in the translation of AANAT. A novel RNA-binding protein hnRNP R widely interacted with the 5' untranslated region (UTR) of AANAT mRNA and contributed to translation through an internal ribosomal entry site (IRES). Fine-tuning of AANAT protein synthesis occurred in response to knockdown and overexpression of hnRNP R. Nocturnal elevation of AANAT protein was dependent on the rhythmic changes of hnRNP R, whose levels are elevated in the pineal gland during nighttime. Increases in hnRNP R additionally improved AANAT production in rat pinealocytes under norepinephrine (NE) treatment. These results suggest that cap-independent translation of AANAT mRNA plays a role in the rhythmic synthesis of melatonin through the recruitment of translational machinery to hnRNP R-bound AANAT mRNA.
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Affiliation(s)
- Hwa-Rim Lee
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
| | - Tae-Don Kim
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
- Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Department of Functional Genomics, University of Science and Technology (UST), Daejeon, Korea
| | - Hyo-Jin Kim
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
| | - Youngseob Jung
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
| | - Dohyun Lee
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
| | - Kyung-Ha Lee
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Do-Yeon Kim
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Kyung-Chul Woo
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
- Newlife Cosmetics R&D Center for Skin Science, Gyeongsansi, Gyeongbuk, Korea
| | - Kyong-Tai Kim
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Korea
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Abstract
U2 snRNP auxiliary factor 65 kDa (U2AF(65)) is a general splicing factor that contacts polypyrimidine (Py) tract and promotes prespliceosome assembly. In this report, we show that U2AF(65) stimulates alternative exon skipping in spinal muscular atrophy (SMA)-related survival motor neuron (SMN) pre-mRNA. A stronger 5' splice-site mutation of alternative exon abolishes the stimulatory effects of U2AF(65). U2AF(65) overexpression promotes its own binding only on the weaker, not the stronger, Py tract. We further demonstrate that U2AF(65) inhibits splicing of flanking introns of alternative exon in both three-exon and two-exon contexts. Similar U2AF(65) effects were observed in Fas (Apo-1/CD95) pre-mRNA. Strikingly, we demonstrate that U2AF(65) even inhibits general splicing of adenovirus major late (Ad ML) or β-globin pre-mRNA. Thus, we conclude that U2AF(65) possesses a splicing Inhibitory function that leads to alternative exon skipping.
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42
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Kim HH, Lee SJ, Gardiner AS, Perrone-Bizzozero NI, Yoo S. Different motif requirements for the localization zipcode element of β-actin mRNA binding by HuD and ZBP1. Nucleic Acids Res 2015; 43:7432-46. [PMID: 26152301 PMCID: PMC4551932 DOI: 10.1093/nar/gkv699] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 06/29/2015] [Indexed: 11/13/2022] Open
Abstract
Interactions of RNA-binding proteins (RBPs) with their target transcripts are essential for regulating gene expression at the posttranscriptional level including mRNA export/localization, stability, and translation. ZBP1 and HuD are RBPs that play pivotal roles in mRNA transport and local translational control in neuronal processes. While HuD possesses three RNA recognition motifs (RRMs), ZBP1 contains two RRMs and four K homology (KH) domains that either increase target specificity or provide a multi-target binding capability. Here we used isolated cis-element sequences of the target mRNA to examine directly protein-RNA interactions in cell-free systems. We found that both ZBP1 and HuD bind the zipcode element in rat β-actin mRNA's 3' UTR. Differences between HuD and ZBP1 were observed in their binding preference to the element. HuD showed a binding preference for U-rich sequence. In contrast, ZBP1 binding to the zipcode RNA depended more on the structural level, as it required the proper spatial organization of a stem-loop that is mainly determined by the U-rich element juxtaposed to the 3' end of a 5'-ACACCC-3' motif. On the basis of this work, we propose that ZBP1 and HuD bind to overlapping sites in the β-actin zipcode, but they recognize different features of this target sequence.
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Affiliation(s)
- Hak Hee Kim
- Nemours Biomedical Research, Alfred I. duPont Hosp. for Children, Wilmington, DE 19803, USA
| | - Seung Joon Lee
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Amy S Gardiner
- Department of Neuroscience, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
| | - Nora I Perrone-Bizzozero
- Department of Neuroscience, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
| | - Soonmoon Yoo
- Nemours Biomedical Research, Alfred I. duPont Hosp. for Children, Wilmington, DE 19803, USA
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43
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In the right place at the right time: visualizing and understanding mRNA localization. Nat Rev Mol Cell Biol 2014; 16:95-109. [PMID: 25549890 DOI: 10.1038/nrm3918] [Citation(s) in RCA: 379] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The spatial regulation of protein translation is an efficient way to create functional and structural asymmetries in cells. Recent research has furthered our understanding of how individual cells spatially organize protein synthesis, by applying innovative technology to characterize the relationship between mRNAs and their regulatory proteins, single-mRNA trafficking dynamics, physiological effects of abrogating mRNA localization in vivo and for endogenous mRNA labelling. The implementation of new imaging technologies has yielded valuable information on mRNA localization, for example, by observing single molecules in tissues. The emerging movements and localization patterns of mRNAs in morphologically distinct unicellular organisms and in neurons have illuminated shared and specialized mechanisms of mRNA localization, and this information is complemented by transgenic and biochemical techniques that reveal the biological consequences of mRNA mislocalization.
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44
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Pluripotent stem cell-based models of spinal muscular atrophy. Mol Cell Neurosci 2014; 64:44-50. [PMID: 25511182 DOI: 10.1016/j.mcn.2014.12.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 12/03/2014] [Accepted: 12/11/2014] [Indexed: 01/01/2023] Open
Abstract
Motor neuron diseases, as the vast majority of neurodegenerative disorders in humans, are incurable conditions that are challenging to study in vitro, owing to the obstacles in obtaining the cell types majorly involved in the pathogenesis. Recent advances in stem cell research, especially in the development of induced pluripotent stem cell (iPSC) technology, have opened up the possibility of generating a substantial amount of disease-specific neuronal cells, including motor neurons and glial cells. The present review analyzes the practical implications of iPSCs, generated from fibroblasts of patients affected by spinal muscular atrophy (SMA), and discusses the challenges in the development and optimization of in vitro disease models. Research on patient-derived disease-specific cells may shed light on the pathological processes behind neuronal dysfunction and death in SMA, thus providing new insights for the development of novel effective therapies.
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45
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Saal L, Briese M, Kneitz S, Glinka M, Sendtner M. Subcellular transcriptome alterations in a cell culture model of spinal muscular atrophy point to widespread defects in axonal growth and presynaptic differentiation. RNA (NEW YORK, N.Y.) 2014; 20:1789-802. [PMID: 25246652 PMCID: PMC4201830 DOI: 10.1261/rna.047373.114] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 08/22/2014] [Indexed: 05/19/2023]
Abstract
Neuronal function critically depends on coordinated subcellular distribution of mRNAs. Disturbed mRNA processing and axonal transport has been found in spinal muscular atrophy and could be causative for dysfunction and degeneration of motoneurons. Despite the advances made in characterizing the transport mechanisms of several axonal mRNAs, an unbiased approach to identify the axonal repertoire of mRNAs in healthy and degenerating motoneurons has been lacking. Here we used compartmentalized microfluidic chambers to investigate the somatodendritic and axonal mRNA content of cultured motoneurons by microarray analysis. In axons, transcripts related to protein synthesis and energy production were enriched relative to the somatodendritic compartment. Knockdown of Smn, the protein deficient in spinal muscular atrophy, produced a large number of transcript alterations in both compartments. Transcripts related to immune functions, including MHC class I genes, and with roles in RNA splicing were up-regulated in the somatodendritic compartment. On the axonal side, transcripts associated with axon growth and synaptic activity were down-regulated. These alterations provide evidence that subcellular localization of transcripts with axonal functions as well as regulation of specific transcripts with nonautonomous functions is disturbed in Smn-deficient motoneurons, most likely contributing to the pathophysiology of spinal muscular atrophy.
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Affiliation(s)
- Lena Saal
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
| | - Michael Briese
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
| | - Susanne Kneitz
- Department of Physiological Chemistry I, Biocenter, University of Wuerzburg, D 97074 Wuerzburg, Germany
| | - Michael Glinka
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
| | - Michael Sendtner
- Institute for Clinical Neurobiology, University of Wuerzburg, D 97078 Wuerzburg, Germany
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46
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Presynaptic localization of Smn and hnRNP R in axon terminals of embryonic and postnatal mouse motoneurons. PLoS One 2014; 9:e110846. [PMID: 25338097 PMCID: PMC4206449 DOI: 10.1371/journal.pone.0110846] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/23/2014] [Indexed: 11/19/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by deficiency of the ubiquitously expressed survival motoneuron (SMN) protein. SMN is crucial component of a complex for the assembly of spliceosomal small nuclear ribonucleoprotein (snRNP) particles. Other cellular functions of SMN are less characterized so far. SMA predominantly affects lower motoneurons, but the cellular basis for this relative specificity is still unknown. In contrast to nonneuronal cells where the protein is mainly localized in perinuclear regions and the nucleus, Smn is also present in dendrites, axons and axonal growth cones of isolated motoneurons invitro. However, this distribution has not been shown invivo and it is not clear whether Smn and hnRNP R are also present in presynaptic axon terminals of motoneurons in postnatal mice. Smn also associates with components not included in the classical SMN complex like RNA-binding proteins FUS, TDP43, HuD and hnRNP R which are involved in RNA processing, subcellular localization and translation. We show here that Smn and hnRNP R are present in presynaptic compartments at neuromuscular endplates of embryonic and postnatal mice. Smn and hnRNP R are localized in close proximity to each other in axons and axon terminals both invitro and invivo. We also provide new evidence for a direct interaction of Smn and hnRNP R invitro and invivo, particularly in the cytosol of motoneurons. These data point to functions of SMN beyond snRNP assembly which could be crucial for recruitment and transport of RNA particles into axons and axon terminals, a mechanism which may contribute to SMA pathogenesis.
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47
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Smith R, Rathod RJ, Rajkumar S, Kennedy D. Nervous translation, do you get the message? A review of mRNPs, mRNA-protein interactions and translational control within cells of the nervous system. Cell Mol Life Sci 2014; 71:3917-37. [PMID: 24952431 PMCID: PMC11113408 DOI: 10.1007/s00018-014-1660-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/22/2014] [Accepted: 05/30/2014] [Indexed: 01/01/2023]
Abstract
In neurons, translation of a message RNA can occur metres away from its transcriptional origin and in normal cells this is orchestrated with perfection. The life of an mRNA will see it pass through multiple steps of processing in the nucleus and the cytoplasm before it reaches its final destination. Processing of mRNA is determined by a myriad of RNA-binding proteins in multi-protein complexes called messenger ribonucleoproteins; however, incorrect processing and delivery of mRNA can cause several human neurological disorders. This review takes us through the life of mRNA from the nucleus to its point of translation in the cytoplasm. The review looks at the various cis and trans factors that act on the mRNA and discusses their roles in different cells of the nervous system and human disorders.
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Affiliation(s)
- Ross Smith
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia,
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48
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Krieger F, Metzger F, Jablonka S. Differentiation defects in primary motoneurons from a SMARD1 mouse model that are insensitive to treatment with low dose PEGylated IGF1. Rare Dis 2014; 2:e29415. [PMID: 25083343 PMCID: PMC4116388 DOI: 10.4161/rdis.29415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 05/26/2014] [Accepted: 05/30/2014] [Indexed: 11/21/2022] Open
Abstract
Muscle atrophy and diaphragmatic palsy are the clinical characteristics of spinal muscular atrophy with respiratory distress type 1 (SMARD1), and are well represented in the neuromuscular degeneration (Nmd2J) mouse, modeling the juvenile form of SMARD1. Both in humans and mice mutations in the IGHMBP2 gene lead to motoneuron degeneration. We could previously demonstrate that treatment with a polyethylene glycol-coupled variant of IGF1 (PEG-IGF1) improves motor functions accompanied by reduced fiber degeneration in the gastrocnemius muscle and the diaphragm, but has no beneficial effect on motoneuron survival. These data raised the question which cell autonomous disease mechanisms contribute to dysfunction and loss of Ighmbp2-deficient motoneurons. An analysis of primary Ighmbp2-deficient motoneurons exhibited differentiation deficits such as reduced spontaneous Ca2+ transients and altered axon elongation, which was not compensated by PEG-IGF1. This points to an IGF1 independent mechanism of motoneuron degeneration that deserves treatment approaches in addition to IGF1.
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Affiliation(s)
- Frank Krieger
- Institute for Clinical Neurobiology; University of Wuerzburg; Wuerzburg, Germany
| | - Friedrich Metzger
- Roche Pharmaceutical Research and Early Development; Roche Innovation Center Basel; F. Hoffmann-La Roche Ltd.; Basel, Switzerland
| | - Sibylle Jablonka
- Institute for Clinical Neurobiology; University of Wuerzburg; Wuerzburg, Germany
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49
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Miura P, Sanfilippo P, Shenker S, Lai EC. Alternative polyadenylation in the nervous system: to what lengths will 3' UTR extensions take us? Bioessays 2014; 36:766-77. [PMID: 24903459 PMCID: PMC4503322 DOI: 10.1002/bies.201300174] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Alternative cleavage and polyadenylation (APA) can diversify coding and non-coding regions, but has particular impact on increasing 3' UTR diversity. Through the gain or loss of regulatory elements such as RNA binding protein and microRNA sites, APA can influence transcript stability, localization, and translational efficiency. Strikingly, the central nervous systems of invertebrate and vertebrate species express a broad range of transcript isoforms bearing extended 3' UTRs. The molecular mechanism that permits proximal 3' end bypass in neurons is mysterious, and only beginning to be elucidated. This landscape of neural 3' UTR extensions, many reaching unprecedented lengths, may help service the unique post-transcriptional regulatory needs of neurons. A combination of approaches, including transcriptome-wide profiling, genetic screening to identify APA factors, biochemical dissection of alternative 3' end formation, and manipulation of individual neural APA targets, will be necessary to gain fuller perspectives on the mechanism and biology of neural-specific 3' UTR lengthening.
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Affiliation(s)
- Pedro Miura
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
| | - Piero Sanfilippo
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
- Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center
| | - Sol Shenker
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
- Tri-Institutional Program in Computational Biology and Medicine, Weill Cornell Medical College
| | - Eric C. Lai
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York NY 10065
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50
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Babin PJ, Goizet C, Raldúa D. Zebrafish models of human motor neuron diseases: advantages and limitations. Prog Neurobiol 2014; 118:36-58. [PMID: 24705136 DOI: 10.1016/j.pneurobio.2014.03.001] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/11/2014] [Accepted: 03/14/2014] [Indexed: 01/08/2023]
Abstract
Motor neuron diseases (MNDs) are an etiologically heterogeneous group of disorders of neurodegenerative origin, which result in degeneration of lower (LMNs) and/or upper motor neurons (UMNs). Neurodegenerative MNDs include pure hereditary spastic paraplegia (HSP), which involves specific degeneration of UMNs, leading to progressive spasticity of the lower limbs. In contrast, spinal muscular atrophy (SMA) involves the specific degeneration of LMNs, with symmetrical muscle weakness and atrophy. Amyotrophic lateral sclerosis (ALS), the most common adult-onset MND, is characterized by the degeneration of both UMNs and LMNs, leading to progressive muscle weakness, atrophy, and spasticity. A review of the comparative neuroanatomy of the human and zebrafish motor systems showed that, while the zebrafish was a homologous model for LMN disorders, such as SMA, it was only partially relevant in the case of UMN disorders, due to the absence of corticospinal and rubrospinal tracts in its central nervous system. Even considering the limitation of this model to fully reproduce the human UMN disorders, zebrafish offer an excellent alternative vertebrate model for the molecular and genetic dissection of MND mechanisms. Its advantages include the conservation of genome and physiological processes and applicable in vivo tools, including easy imaging, loss or gain of function methods, behavioral tests to examine changes in motor activity, and the ease of simultaneous chemical/drug testing on large numbers of animals. This facilitates the assessment of the environmental origin of MNDs, alone or in combination with genetic traits and putative modifier genes. Positive hits obtained by phenotype-based small-molecule screening using zebrafish may potentially be effective drugs for treatment of human MNDs.
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Affiliation(s)
- Patrick J Babin
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France.
| | - Cyril Goizet
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France; CHU Bordeaux, Hôpital Pellegrin, Service de Génétique Médicale, Bordeaux, France
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