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Chaudhary R, Rehman M, Agarwal V, Kumar A, Kaushik AS, Srivastava S, Srivastava S, Verma R, Rajinikanth PS, Mishra V. Terra incognita of glial cell dynamics in the etiology of leukodystrophies: Broadening disease and therapeutic perspectives. Life Sci 2024; 354:122953. [PMID: 39122110 DOI: 10.1016/j.lfs.2024.122953] [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: 02/05/2024] [Revised: 07/09/2024] [Accepted: 08/05/2024] [Indexed: 08/12/2024]
Abstract
Neuroglial cells, also known as glia, are primarily characterized as auxiliary cells within the central nervous system (CNS). The recent findings have shed light on their significance in numerous physiological processes and their involvement in various neurological disorders. Leukodystrophies encompass an array of rare and hereditary neurodegenerative conditions that were initially characterized by the deficiency, aberration, or degradation of myelin sheath within CNS. The primary cellular populations that experience significant alterations are astrocytes, oligodendrocytes and microglia. These glial cells are either structurally or metabolically impaired due to inherent cellular dysfunction. Alternatively, they may fall victim to the accumulation of harmful by-products resulting from metabolic disturbances. In either situation, the possible replacement of glial cells through the utilization of implanted tissue or stem cell-derived human neural or glial progenitor cells hold great promise as a therapeutic strategy for both the restoration of structural integrity through remyelination and the amelioration of metabolic deficiencies. Various emerging treatment strategies like stem cell therapy, ex-vivo gene therapy, infusion of adeno-associated virus vectors, emerging RNA-based therapies as well as long-term therapies have demonstrated success in pre-clinical studies and show promise for rapid clinical translation. Here, we addressed various leukodystrophies in a comprehensive and detailed manner as well as provide prospective therapeutic interventions that are being considered for clinical trials. Further, we aim to emphasize the crucial role of different glial cells in the pathogenesis of leukodystrophies. By doing so, we hope to advance our understanding of the disease, elucidate underlying mechanisms, and facilitate the development of potential treatment interventions.
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Affiliation(s)
- Rishabh Chaudhary
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Mujeeba Rehman
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Vipul Agarwal
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Anand Kumar
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Arjun Singh Kaushik
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Siddhi Srivastava
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Sukriti Srivastava
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Rajkumar Verma
- University of Connecticut School of Medicine, 200 Academic Way, Farmington, CT 06032, USA
| | - P S Rajinikanth
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India
| | - Vikas Mishra
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, U.P., India.
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Perrier S, Gauquelin L, Bernard G. Inherited white matter disorders: Hypomyelination (myelin disorders). HANDBOOK OF CLINICAL NEUROLOGY 2024; 204:197-223. [PMID: 39322379 DOI: 10.1016/b978-0-323-99209-1.00014-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2024]
Abstract
Hypomyelinating leukodystrophies are a subset of genetic white matter diseases characterized by insufficient myelin deposition during development. MRI patterns are used to identify hypomyelinating disorders, and genetic testing is used to determine the causal genes implicated in individual disease forms. Clinical course can range from severe, with patients manifesting neurologic symptoms in infancy or early childhood, to mild, with onset in adolescence or adulthood. This chapter discusses the most common hypomyelinating leukodystrophies, including X-linked Pelizaeus-Merzbacher disease and other PLP1-related disorders, autosomal recessive Pelizaeus-Merzbacher-like disease, and POLR3-related leukodystrophy. PLP1-related disorders are caused by hemizygous pathogenic variants in the proteolipid protein 1 (PLP1) gene, and encompass classic Pelizaeus-Merzbacher disease, the severe connatal form, PLP1-null syndrome, spastic paraplegia type 2, and hypomyelination of early myelinating structures. Pelizaeus-Merzbacher-like disease presents a similar clinical picture to Pelizaeus-Merzbacher disease, however, it is caused by biallelic pathogenic variants in the GJC2 gene, which encodes for the gap junction protein Connexin-47. POLR3-related leukodystrophy, or 4H leukodystrophy (hypomyelination, hypodontia, and hypogonadotropic hypogonadism), is caused by biallelic pathogenic variants in genes encoding specific subunits of the transcription enzyme RNA polymerase III. In this chapter, the clinical features, disease pathophysiology and genetics, imaging patterns, as well as supportive and future therapies are discussed for each disorder.
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Affiliation(s)
- Stefanie Perrier
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada; Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montréal, QC, Canada
| | - Laurence Gauquelin
- Division of Pediatric Neurology, Department of Pediatrics, CHUL et Centre Mère-Enfant Soleil du CHU de Québec-Université Laval, Québec, QC, Canada
| | - Geneviève Bernard
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada; Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montréal, QC, Canada; Departments of Pediatrics and Human Genetics, McGill University, Montréal, QC, Canada.
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Deep intronic deletion in intron 3 of PLP1 is associated with a severe phenotype of Pelizaeus-Merzbacher disease. Hum Genome Var 2021; 8:14. [PMID: 33795668 PMCID: PMC8016919 DOI: 10.1038/s41439-021-00144-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/26/2021] [Accepted: 03/10/2021] [Indexed: 11/18/2022] Open
Abstract
Recently, altered PLP1 splicing was confirmed as a genetic cause of hypomyelination of early myelinating structures (HEMS). A novel deep intronic deletion in intron 3 of PLP1 (NM_000533.5: c.453+59_+259del) was identified, and an in vitro minigene assay detected abnormal splicing patterns. However, the clinical and radiological findings of the patient were compatible with a severe phenotype of Pelizaeus-Merzbacher disease rather than HEMS, which may be due to undetected abnormal PLP1 splicing.
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Garcia LM, Hacker JL, Sase S, Adang L, Almad A. Glial cells in the driver seat of leukodystrophy pathogenesis. Neurobiol Dis 2020; 146:105087. [PMID: 32977022 DOI: 10.1016/j.nbd.2020.105087] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 08/16/2020] [Accepted: 09/18/2020] [Indexed: 01/24/2023] Open
Abstract
Glia cells are often viewed as support cells in the central nervous system, but recent discoveries highlight their importance in physiological functions and in neurological diseases. Central to this are leukodystrophies, a group of progressive, neurogenetic disease affecting white matter pathology. In this review, we take a closer look at multiple leukodystrophies, classified based on the primary glial cell type that is affected. While white matter diseases involve oligodendrocyte and myelin loss, we discuss how astrocytes and microglia are affected and impinge on oligodendrocyte, myelin and axonal pathology. We provide an overview of the leukodystrophies covering their hallmark features, clinical phenotypes, diverse molecular pathways, and potential therapeutics for clinical trials. Glial cells are gaining momentum as cellular therapeutic targets for treatment of demyelinating diseases such as leukodystrophies, currently with no treatment options. Here, we bring the much needed attention to role of glia in leukodystrophies, an integral step towards furthering disease comprehension, understanding mechanisms and developing future therapeutics.
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Affiliation(s)
- Luis M Garcia
- Department of Neurology, The Children's Hospital of Philadelphia, PA, Pennsylvania, USA
| | - Julia L Hacker
- Department of Neurology, The Children's Hospital of Philadelphia, PA, Pennsylvania, USA
| | - Sunetra Sase
- Department of Neurology, The Children's Hospital of Philadelphia, PA, Pennsylvania, USA
| | - Laura Adang
- Department of Neurology, The Children's Hospital of Philadelphia, PA, Pennsylvania, USA
| | - Akshata Almad
- Department of Neurology, The Children's Hospital of Philadelphia, PA, Pennsylvania, USA.
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Kim MJ, Petratos S. Oligodendroglial Lineage Cells in Thyroid Hormone-Deprived Conditions. Stem Cells Int 2019; 2019:5496891. [PMID: 31182964 PMCID: PMC6515029 DOI: 10.1155/2019/5496891] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/20/2019] [Indexed: 01/06/2023] Open
Abstract
Oligodendrocytes are supporting glial cells that ensure the metabolism and homeostasis of neurons with specific synaptic axoglial interactions in the central nervous system. These require key myelinating glial trophic signals important for growth and metabolism. Thyroid hormone (TH) is one such trophic signal that regulates oligodendrocyte maturation, myelination, and oligodendroglial synaptic dynamics via either genomic or nongenomic pathways. The intracellular and extracellular transport of TH is facilitated by a specific transmembrane transporter known as the monocarboxylate transporter 8 (MCT8). Dysfunction of the MCT8 due to mutation, inhibition, or downregulation during brain development leads to inherited hypomyelination, which manifests as psychomotor retardation in the X-linked inherited Allan-Herndon-Dudley syndrome (AHDS). In particular, oligodendroglial-specific MCT8 deficiency may restrict the intracellular T3 availability, culminating in deficient metabolic communication between the oligodendrocytes and the neurons they ensheath, potentially promulgating neurodegenerative adult diseases such as multiple sclerosis (MS). Based on the therapeutic effects exhibited by TH in various preclinical studies, particularly related to its remyelinating potential, TH has now entered the initial stages of a clinical trial to test the therapeutic efficacy in relapsing-remitting MS patients (NCT02506751). However, TH analogs, such as DITPA or Triac, may well serve as future therapeutic options to rescue mature oligodendrocytes and/or promote oligodendrocyte precursor cell differentiation in an environment of MCT8 deficiency within the CNS. This review outlines the therapeutic strategies to overcome the differentiation blockade of oligodendrocyte precursors and maintain mature axoglial interactions in TH-deprived conditions.
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Affiliation(s)
- Min Joung Kim
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia
| | - Steven Petratos
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia
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Inoue K. Pelizaeus-Merzbacher Disease: Molecular and Cellular Pathologies and Associated Phenotypes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:201-216. [PMID: 31760646 DOI: 10.1007/978-981-32-9636-7_13] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Pelizaeus-Merzbacher disease (PMD) represents a group of disorders known as hypomyelinating leukodystrophies, which are characterized by abnormal development and maintenance of myelin in the central nervous system. PMD is caused by different types of mutations in the proteolipid protein 1 (PLP1) gene, which encodes a major myelin membrane lipoprotein. These mutations in the PLP1 gene result in distinct cellular and molecular pathologies and a spectrum of clinical phenotypes. In this chapter, I discuss the historical aspects and current understanding of the mechanisms underlying how different PLP1 mutations disrupt the normal process of myelination and result in PMD and other disorders.
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Affiliation(s)
- Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan.
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Tantzer S, Sperle K, Kenaley K, Taube J, Hobson GM. Morpholino Antisense Oligomers as a Potential Therapeutic Option for the Correction of Alternative Splicing in PMD, SPG2, and HEMS. MOLECULAR THERAPY. NUCLEIC ACIDS 2018; 12:420-432. [PMID: 30195779 PMCID: PMC6036941 DOI: 10.1016/j.omtn.2018.05.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 05/22/2018] [Indexed: 01/10/2023]
Abstract
DNA variants of the proteolipid protein 1 gene (PLP1) that shift PLP1/DM20 alternative splicing away from the PLP1 form toward DM20 cause the allelic X-linked leukodystrophies Pelizaeus-Merzbacher disease (PMD), spastic paraplegia 2 (SPG2), and hypomyelination of early myelinating structures (HEMS). We designed a morpholino oligomer (MO-PLP) to block use of the DM20 5' splice donor site, thereby shifting alternative splicing toward the PLP1 5' splice site. Treatment of an immature oligodendrocyte cell line with MO-PLP significantly shifted alternative splicing toward PLP1 expression from the endogenous gene and from transfected human minigene splicing constructs harboring patient variants known to reduce the amount of the PLP1 spliced product. Additionally, a single intracerebroventricular injection of MO-PLP into the brains of neonatal mice, carrying a deletion of an intronic splicing enhancer identified in a PMD patient that reduces the Plp1 spliced form, corrected alternative splicing at both RNA and protein levels in the CNS. The effect lasted to post-natal day 90, well beyond the early post-natal spike in myelination and PLP production. Further, the single injection produced a sustained reduction of inflammatory markers in the brains of the mice. Our results suggest that morpholino oligomers have therapeutic potential for the treatment of PMD, SPG2, and HEMS.
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Affiliation(s)
- Stephanie Tantzer
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Karen Sperle
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Kaitlin Kenaley
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; Department of Pediatrics/Neonatology, Christiana Care Health System, Newark, DE 19713, USA
| | - Jennifer Taube
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Grace M Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA; Department of Pediatrics, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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Inoue K. Cellular Pathology of Pelizaeus-Merzbacher Disease Involving Chaperones Associated with Endoplasmic Reticulum Stress. Front Mol Biosci 2017; 4:7. [PMID: 28286750 PMCID: PMC5323380 DOI: 10.3389/fmolb.2017.00007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 02/09/2017] [Indexed: 11/23/2022] Open
Abstract
Disease-causing mutations in genes encoding membrane proteins may lead to the production of aberrant polypeptides that accumulate in the endoplasmic reticulum (ER). These mutant proteins have detrimental conformational changes or misfolding events, which result in the triggering of the unfolded protein response (UPR). UPR is a cellular pathway that reduces ER stress by generally inhibiting translation, increasing ER chaperones levels, or inducing cell apoptosis in severe ER stress. This process has been implicated in the cellular pathology of many neurological disorders, including Pelizaeus-Merzbacher disease (PMD). PMD is a rare pediatric disorder characterized by the failure in the myelination process of the central nervous system (CNS). PMD is caused by mutations in the PLP1 gene, which encodes a major myelin membrane protein. Severe clinical PMD phenotypes appear to be the result of cell toxicity, due to the accumulation of PLP1 mutant proteins and not due to the lack of functional PLP1. Therefore, it is important to clarify the pathological mechanisms by which the PLP1 mutants negatively impact the myelin-generating cells, called oligodendrocytes, to overcome this devastating disease. This review discusses how PLP1 mutant proteins change protein homeostasis in the ER of oligodendrocytes, especially focusing on the reaction of ER chaperones against the accumulation of PLP1 mutant proteins that cause PMD.
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Affiliation(s)
- Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry Kodaira, Japan
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Laukka JJ, Kamholz J, Bessert D, Skoff RP. Novel pathologic findings in patients with Pelizaeus-Merzbacher disease. Neurosci Lett 2016; 627:222-32. [PMID: 27222925 PMCID: PMC4948744 DOI: 10.1016/j.neulet.2016.05.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/13/2016] [Accepted: 05/14/2016] [Indexed: 10/21/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is an X-linked inherited hypomyelinating disorder caused by mutations in the gene encoding proteolipid protein (PLP), the major structural protein in central nervous system (CNS) myelin. Prior to our study, whether hypomyelination in PMD was caused by demyelination, abnormally thin sheaths or failure to form myelin was unknown. In this study, we compared the microscopic pathology of myelin from brain tissue of 3 PMD patients with PLP1 duplications to that of a patient with a complete PLP1 deletion. Autopsy tissue procured from PMD patients was embedded in paraffin for immunocytochemistry and plastic for electron microscopy to obtain highresolution fiber pathology of cerebrum and corpus callosum. Through histological stains, immunocytochemistry and electron microscopy, our study illustrates unique pathologic findings between the two different types of mutations. Characteristic of the patient with a PLP1 deletion, myelin sheaths showed splitting and decompaction of myelin, confirming for the first time that myelin in PLP1 deletion patients is similar to that of rodent models with gene deletions. Myelin thickness and g-ratios of some fibers, in relation to axon diameter was abnormally thin, suggesting that oligodendrocytes remain metabolically functional and/or are attempting to make myelin. Many fibers showed swollen, progressive degenerative changes to axons in addition to the dissolution of myelin. All three duplication cases shared remarkable fiber pathology including swellings, constriction and/or transection and involution of myelin. Characteristic of PLP1 duplication patients, many axons showed segmental demyelination along their length. Still other axons had abnormally thick myelin sheaths, suggestive of continued myelination. Thus, each type of mutation exhibited unique pathology even though commonality to both mutations included involution of myelin, myelin balls and degeneration of axons. This pathology study describes findings unique to each mutation that suggests the mechanism causing fiber pathology is likewise heterogeneous.
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Affiliation(s)
- Jeremy J Laukka
- Department of Neuroscience, University of Toledo, College of Medicine and Life Science, Toledo, OH 43614, United States; Department of Neurology, University of Toledo, College of Medicine and Life Science, Toledo, OH 43614, United States.
| | - John Kamholz
- Center for Molecular Medicine and Genetics, Wayne State University, School of Medicine, Detroit, MI 48201, United States; Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, IA 52242, United States
| | - Denise Bessert
- Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, Detroit, MI 48201, United States
| | - Robert P Skoff
- Center for Molecular Medicine and Genetics, Wayne State University, School of Medicine, Detroit, MI 48201, United States; Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, Detroit, MI 48201, United States
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Gonzalez-Pena D, Nixon SE, Southey BR, Lawson MA, McCusker RH, Hernandez AG, Dantzer R, Kelley KW, Rodriguez-Zas SL. Differential Transcriptome Networks between IDO1-Knockout and Wild-Type Mice in Brain Microglia and Macrophages. PLoS One 2016; 11:e0157727. [PMID: 27314674 PMCID: PMC4912085 DOI: 10.1371/journal.pone.0157727] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 05/06/2016] [Indexed: 11/19/2022] Open
Abstract
Microglia in the brain and macrophages in peripheral organs are cell types responsible for immune response to challenges. Indoleamine 2,3-dioxygenase 1 (IDO1) is an immunomodulatory enzyme of the tryptophan pathway that is expressed in the brain. The higher activity of IDO1 in response to immune challenge has been implicated in behavioral disorders. The impact of IDO1 depletion on the microglia transcriptome has not been studied. An investigation of the transcript networks in the brain microglia from IDO1-knockout (IDO1-KO) mice was undertaken, relative to peripheral macrophages and to wild-type (WT) mice under unchallenged conditions. Over 105 transcript isoforms were differentially expressed between WT and IDO1-KO within cell type. Within microglia, Saa3 and Irg1 were over-expressed in IDO1-KO relative to WT. Within macrophages, Csf3 and Sele were over-expressed in IDO1-KO relative to WT. Among the genes differentially expressed between strains, enriched biological processes included ion homeostasis and ensheathment of neurons within microglia, and cytokine and chemokine expression within macrophages. Over 11,110 transcript isoforms were differentially expressed between microglia and macrophages and of these, over 10,800 transcripts overlapped between strains. Enriched biological processes among the genes over- and under-expressed in microglia relative to macrophages included cell adhesion and apoptosis, respectively. Detected only in microglia or macrophages were 421 and 43 transcript isoforms, respectively. Alternative splicing between cell types based on differential transcript isoform abundance was detected in 210 genes including Phf11d, H2afy, and Abr. Across strains, networks depicted a predominance of genes under-expressed in microglia relative to macrophages that may be a precursor for the different response of both cell types to challenges. The detected transcriptome differences enhance the understanding of the role of IDO1 in the microglia transcriptome under unchallenged conditions.
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Affiliation(s)
- Dianelys Gonzalez-Pena
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Scott E. Nixon
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Bruce R. Southey
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Marcus A. Lawson
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Robert H. McCusker
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Alvaro G. Hernandez
- Department of Symptom Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Robert Dantzer
- High-Throughput Sequencing and Genotyping Unit, Roy J. Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Keith W. Kelley
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Sandra L. Rodriguez-Zas
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
- Department of Statistics, University of Illinois at Urbana-Champaign, Champaign, Illinois, United States of America
- Carle Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
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Kevelam SH, Taube JR, van Spaendonk RML, Bertini E, Sperle K, Tarnopolsky M, Tonduti D, Valente EM, Travaglini L, Sistermans EA, Bernard G, Catsman-Berrevoets CE, van Karnebeek CDM, Østergaard JR, Friederich RL, Fawzi Elsaid M, Schieving JH, Tarailo-Graovac M, Orcesi S, Steenweg ME, van Berkel CGM, Waisfisz Q, Abbink TEM, van der Knaap MS, Hobson GM, Wolf NI. Altered PLP1 splicing causes hypomyelination of early myelinating structures. Ann Clin Transl Neurol 2015; 2:648-61. [PMID: 26125040 PMCID: PMC4479525 DOI: 10.1002/acn3.203] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/03/2015] [Accepted: 03/12/2015] [Indexed: 12/19/2022] Open
Abstract
Objective The objective of this study was to investigate the genetic etiology of the X-linked disorder “Hypomyelination of Early Myelinating Structures” (HEMS). Methods We included 16 patients from 10 families diagnosed with HEMS by brain MRI criteria. Exome sequencing was used to search for causal mutations. In silico analysis of effects of the mutations on splicing and RNA folding was performed. In vitro gene splicing was examined in RNA from patients’ fibroblasts and an immortalized immature oligodendrocyte cell line after transfection with mutant minigene splicing constructs. Results All patients had unusual hemizygous mutations of PLP1 located in exon 3B (one deletion, one missense and two silent), which is spliced out in isoform DM20, or in intron 3 (five mutations). The deletion led to truncation of PLP1, but not DM20. Four mutations were predicted to affect PLP1/DM20 alternative splicing by creating exonic splicing silencer motifs or new splice donor sites or by affecting the local RNA structure of the PLP1 splice donor site. Four deep intronic mutations were predicted to destabilize a long-distance interaction structure in the secondary PLP1 RNA fragment involved in regulating PLP1/DM20 alternative splicing. Splicing studies in fibroblasts and transfected cells confirmed a decreased PLP1/DM20 ratio. Interpretation Brain structures that normally myelinate early are poorly myelinated in HEMS, while they are the best myelinated structures in Pelizaeus–Merzbacher disease, also caused by PLP1 alterations. Our data extend the phenotypic spectrum of PLP1-related disorders indicating that normal PLP1/DM20 alternative splicing is essential for early myelination and support the need to include intron 3 in diagnostic sequencing.
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Affiliation(s)
- Sietske H Kevelam
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - Jennifer R Taube
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children Wilmington, Delaware
| | | | - Enrico Bertini
- Unit for Neuromuscular and Neurodegenerative Diseases, Laboratory of Molecular Medicine, Bambino Gesu' Children's Research Hospital, IRCCS Rome, Italy
| | - Karen Sperle
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children Wilmington, Delaware
| | - Mark Tarnopolsky
- Department of Pediatrics, McMaster Children's Hospital Hamilton, Ontario, Canada
| | - Davide Tonduti
- Child Neuropsychiatry Unit, Department of Brain and Behavioral Sciences, University of Pavia Pavia, Italy
| | - Enza Maria Valente
- Department of Medicine and Surgery, University of Salerno Salerno, Italy ; CSS-Mendel Institute, IRCCS Casa Sollievo della Sofferenza San Giovanni Rotondo, Italy
| | - Lorena Travaglini
- Unit for Neuromuscular and Neurodegenerative Diseases, Laboratory of Molecular Medicine, Bambino Gesu' Children's Research Hospital, IRCCS Rome, Italy
| | - Erik A Sistermans
- Department of Clinical Genetics, VU University Medical Center Amsterdam, The Netherlands
| | - Geneviève Bernard
- Division of Pediatric Neurology, Departments of Pediatrics, Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Center Montreal, Quebec, Canada
| | - Coriene E Catsman-Berrevoets
- Department of Pediatric Neurology, Erasmus University Hospital - Sophia Children's Hospital Rotterdam, The Netherlands
| | - Clara D M van Karnebeek
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, Centre for Molecular Medicine and Therapeutics, University of British Columbia Vancouver, Canada
| | - John R Østergaard
- Centre for Rare diseases, Department of Paediatrics, Aarhus University Hospital Aarhus, Denmark
| | - Richard L Friederich
- Department of Child Neurology, Kaiser Permanente Pediatric Specialties Roseville, California
| | | | - Jolanda H Schieving
- Department of Child Neurology, Radboud University Medical Center Nijmegen, The Netherlands
| | - Maja Tarailo-Graovac
- Department of Medical Genetics, University of British Colombia Vancouver, Canada
| | - Simona Orcesi
- Child Neurology and Psychiatry Unit, C. Mondino National Neurological Institute Pavia, Italy
| | - Marjan E Steenweg
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - Carola G M van Berkel
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands
| | - Quinten Waisfisz
- Department of Clinical Genetics, VU University Medical Center Amsterdam, The Netherlands
| | - Truus E M Abbink
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - Marjo S van der Knaap
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands ; Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, The Netherlands
| | - Grace M Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children Wilmington, Delaware ; Department of Biological Sciences, University of Delaware Newark, Delaware ; Department of Pediatrics, Jefferson Medical College, Thomas Jefferson University Philadelphia, Pennsylvania
| | - Nicole I Wolf
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
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12
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Kubota K, Saito Y, Ohba C, Saitsu H, Fukuyama T, Ishiyama A, Saito T, Komaki H, Nakagawa E, Sugai K, Sasaki M, Matsumoto N. Brain magnetic resonance imaging findings and auditory brainstem response in a child with spastic paraplegia 2 due to a PLP1 splice site mutation. Brain Dev 2015; 37:158-62. [PMID: 24685771 DOI: 10.1016/j.braindev.2014.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/26/2014] [Accepted: 03/05/2014] [Indexed: 10/25/2022]
Abstract
A boy with spastic paraplegia type 2 (SPG2) due to a novel splice site mutation of PLP1 presented with progressive spasticity of lower limbs, which was first observed during late infancy, when he gained the ability to walk with support. His speech was slow and he had dysarthria. The patient showed mildly delayed intellectual development. Subtotal dysmyelination in the central nervous system was revealed, which was especially prominent in structures known to be myelinated during earlier period, whereas structures that are myelinated later were better myelinated. These findings on the brain magnetic resonance imaging were unusual for subjects with PLP1 mutations. Peaks I and II of the auditory brainstem response (ABR) were normally provoked, but peaks III-V were not clearly demarcated, similarly to the findings in Pelizaeus-Merzbacher disease. These findings of brain MRI and ABR may be characteristic for a subtype of SPG2 patients.
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Affiliation(s)
- Kazuo Kubota
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yoshiaki Saito
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan.
| | - Chihiro Ohba
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Kanazawa-ku, Yokohama, Japan
| | - Hirotomo Saitsu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Kanazawa-ku, Yokohama, Japan
| | | | - Akihiko Ishiyama
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Takashi Saito
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hirofumi Komaki
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Eiji Nakagawa
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Kenji Sugai
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Masayuki Sasaki
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Kanazawa-ku, Yokohama, Japan
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13
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Siva K, Covello G, Denti MA. Exon-skipping antisense oligonucleotides to correct missplicing in neurogenetic diseases. Nucleic Acid Ther 2014; 24:69-86. [PMID: 24506781 DOI: 10.1089/nat.2013.0461] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Alternative splicing is an important regulator of the transcriptome. However, mutations may cause alteration of splicing patterns, which in turn leads to disease. During the past 10 years, exon skipping has been looked upon as a powerful tool for correction of missplicing in disease and progress has been made towards clinical trials. In this review, we discuss the use of antisense oligonucleotides to correct splicing defects through exon skipping, with a special focus on diseases affecting the nervous system, and the latest stage achieved in its progress.
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Affiliation(s)
- Kavitha Siva
- 1 Center for Integrative Biology (CIBIO), University of Trento , Trento, Italy
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14
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Taube JR, Sperle K, Banser L, Seeman P, Cavan BCV, Garbern JY, Hobson GM. PMD patient mutations reveal a long-distance intronic interaction that regulates PLP1/DM20 alternative splicing. Hum Mol Genet 2014; 23:5464-78. [PMID: 24890387 DOI: 10.1093/hmg/ddu271] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Alternative splicing of the proteolipid protein 1 gene (PLP1) produces two forms, PLP1 and DM20, due to alternative use of 5' splice sites with the same acceptor site in intron 3. The PLP1 form predominates in central nervous system RNA. Mutations that reduce the ratio of PLP1 to DM20, whether mutant or normal protein is formed, result in the X-linked leukodystrophy Pelizaeus-Merzbacher disease (PMD). We investigated the ability of sequences throughout PLP1 intron 3 to regulate alternative splicing using a splicing minigene construct transfected into the oligodendrocyte cell line, Oli-neu. Our data reveal that the alternative splice of PLP1 is regulated by a long-distance interaction between two highly conserved elements that are separated by 581 bases within the 1071-base intron 3. Further, our data suggest that a base-pairing secondary structure forms between these two elements, and we demonstrate that mutations of either element designed to destabilize the secondary structure decreased the PLP1/DM20 ratio, while swap mutations designed to restore the structure brought the PLP1/DM20 ratio to near normal levels. Sequence analysis of intron 3 in families with clinical symptoms of PMD who did not have coding-region mutations revealed mutations that segregated with disease in three families. We showed that these patient mutations, which potentially destabilize the secondary structure, also reduced the PLP1/DM20 ratio. This is the first report of patient mutations causing disease by disruption of a long-distance intronic interaction controlling alternative splicing. This finding has important implications for molecular diagnostics of PMD.
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Affiliation(s)
- Jennifer R Taube
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Karen Sperle
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Linda Banser
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Pavel Seeman
- Department of Child Neurology, DNA Laboratory, 2nd School of Medicine, Charles University and University Hospital Motol, 150 06 Prague 5, Czech Republic
| | | | - James Y Garbern
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Grace M Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA, Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA and Department of Pediatrics, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
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15
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Clinically relevant intronic splicing enhancer mutation in myelin proteolipid protein leads to progressive microglia and astrocyte activation in white and gray matter regions of the brain. J Neuroinflammation 2013; 10:146. [PMID: 24314267 PMCID: PMC3906979 DOI: 10.1186/1742-2094-10-146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/27/2013] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION Mutations in proteolipid protein (PLP), the most abundant myelin protein in the CNS, cause the X-linked dysmyelinating leukodystrophies, Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia type 2 (SPG2). Point mutations, deletion, and duplication of the PLP1 gene cause PMD/SPG2 with varying clinical presentation. Deletion of an intronic splicing enhancer (ISEdel) within intron 3 of the PLP1 gene is associated with a mild form of PMD. Clinical and preclinical studies have indicated that mutations in myelin proteins, including PLP, can induce neuroinflammation, but the temporal and spatial onset of the reactive glia response in a clinically relevant mild form of PMD has not been defined. METHODS A PLP-ISEdel knockin mouse was used to examine the behavioral and neuroinflammatory consequences of a deletion within intron 3 of the PLP gene, at two time points (two and four months old) early in the pathological progression. Mice were characterized functionally using the open field task, elevated plus maze, and nesting behavior. Quantitative neuropathological analysis was for markers of astrocytes (GFAP), microglia (IBA1, CD68, MHCII) and axons (APP). The Aperio ScanScope was used to generate a digital, high magnification photomicrograph of entire brain sections. These digital slides were used to quantify the immunohistochemical staining in ten different brain regions to assess the regional heterogeneity in the reactive astrocyte and microglial response. RESULTS The PLP-ISEdel mice exhibited behavioral deficits in the open field and nesting behavior at two months, which did not worsen by four months of age. A marker of axonal injury (APP) increased from two months to four months of age. Striking was the robust reactive astrocyte and microglia response which was also progressive. In the two-month-old mice, the astrocyte and microglia reactivity was most apparent in white matter rich regions of the brain. By four months of age the gliosis had become widespread and included both white as well as gray matter regions of the brain. CONCLUSIONS Our results indicate, along with other preclinical models of PMD, that an early reactive glia response occurs following mutations in the PLP gene, which may represent a potentially clinically relevant, oligodendrocyte-independent therapeutic target for PMD.
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Autoimmune T-cell reactivity to myelin proteolipids and glycolipids in multiple sclerosis. Mult Scler Int 2013; 2013:151427. [PMID: 24312732 PMCID: PMC3839122 DOI: 10.1155/2013/151427] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/12/2013] [Indexed: 11/17/2022] Open
Abstract
Central nervous system (CNS) myelin, the likely major target of autoimmune attack in multiple sclerosis (MS), contains a number of unique components that are potential targets of the attack. Two classes of molecules that are greatly enriched in CNS myelin compared to other parts of the body are certain types of proteolipids and glycolipids. Due to the hydrophobic nature of both of these classes of molecules, they present challenges for use in immunological assays and have therefore been somewhat neglected in studies of T-cell reactivity in MS compared to more soluble molecules such as the myelin basic proteins and the extracellular domain of myelin oligodendrocyte glycoprotein. This review firstly looks at the makeup of CNS myelin, with an emphasis on proteolipids and glycolipids. Next, a retrospective of what is known of T-cell reactivity directed against proteolipids and glycolipids in patients with MS is presented, and the implications of the findings are discussed. Finally, this review considers the question of what would be required to prove a definite role for autoreactivity against proteolipids and glycolipids in the pathogenesis of MS.
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17
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Regis S, Corsolini F, Grossi S, Tappino B, Cooper DN, Filocamo M. Restoration of the normal splicing pattern of the PLP1 gene by means of an antisense oligonucleotide directed against an exonic mutation. PLoS One 2013; 8:e73633. [PMID: 24019930 PMCID: PMC3760819 DOI: 10.1371/journal.pone.0073633] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 07/30/2013] [Indexed: 11/19/2022] Open
Abstract
An exonic missense mutation, c.436C>G, in the PLP1 gene of a patient affected by the hypomyelinating leukodystrophy, Pelizaeus–Merzbacher disease, has previously been found to be responsible for the alteration of the canonical alternative splicing profile of the PLP1 gene leading to the loss of the longer PLP isoform. Here we show that the presence of the c.436C>G mutation served to introduce regulatory motifs that appear to be responsible for the perturbed splicing pattern that led to loss of the major PLP transcript. With the aim of disrupting the interaction between the PLP1 splicing regulatory motifs and their cognate splicing factors, we designed an antisense oligonucleotide-based in vitro correction protocol that successfully restored PLP transcript production in oligodendrocyte precursor cells.
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Affiliation(s)
- Stefano Regis
- Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto G. Gaslini, Genova, Italy
| | - Fabio Corsolini
- Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto G. Gaslini, Genova, Italy
| | - Serena Grossi
- Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto G. Gaslini, Genova, Italy
| | - Barbara Tappino
- Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto G. Gaslini, Genova, Italy
| | - David N. Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Mirella Filocamo
- Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto G. Gaslini, Genova, Italy
- * E-mail:
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18
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Moore S, Patel R, Hannsun G, Yang J, Tiwari-Woodruff SK. Sex chromosome complement influences functional callosal myelination. Neuroscience 2013; 245:166-78. [PMID: 23597832 DOI: 10.1016/j.neuroscience.2013.04.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/01/2013] [Accepted: 04/02/2013] [Indexed: 12/29/2022]
Abstract
In addition to androgen differences between males and females, there are genetic differences that are caused by unequal dosage of sex chromosome genes. Using the cuprizone-induced demyelination model, we recently showed that surgical gonadectomy of adult mice resulted in decreased normal myelination and remyelination compared to gonadally intact animals, suggesting a supporting role for sex hormones in the maintenance of myelination. However, inherent sex differences in normal myelination and remyelination persisted even after gonadectomy, with males consistently remyelinating to a lesser extent relative to normal myelination as assayed by axon conduction and immunohistochemistry. This suggests a potential role for the sex chromosome complement in mediating the differential rates of remyelination observed in males and females. The present study focuses on the impact that sex chromosomes might have on these myelination differences. Making use of the four core-genotype mice and cuprizone-diet induced demyelination/remyelination paradigm, our results demonstrate sex chromosome-mediated asymmetry between XX and XY mice. The rate of functional remyelination following cuprizone diet-induced callosal demyelination in four core-genotype mice is attenuated in XY compared to XX animals of both gonadal sexes. Importantly, this difference arises only in the absence of circulating sex hormones following gonadectomy and confirms the role of sex hormones in the remyelination process reported earlier by our group. Because a genotype-mediated difference only arises following gonadectomy, the chromosomal contribution to myelination and remyelination is subtle yet significant. To explain this difference, we propose a possible asymmetry in the expression of myelination-related genes in XX vs. XY mice that needs to be investigated in future studies.
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Affiliation(s)
- S Moore
- Multiple Sclerosis Program, Department of Neurology, School of Medicine, University of California, Los Angeles, CA 90095, USA
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19
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Huyghe A, Horzinski L, Hénaut A, Gaillard M, Bertini E, Schiffmann R, Rodriguez D, Dantal Y, Boespflug-Tanguy O, Fogli A. Developmental splicing deregulation in leukodystrophies related to EIF2B mutations. PLoS One 2012; 7:e38264. [PMID: 22737209 PMCID: PMC3380860 DOI: 10.1371/journal.pone.0038264] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 05/03/2012] [Indexed: 11/19/2022] Open
Abstract
Leukodystrophies (LD) are rare inherited disorders that primarily affect the white matter (WM) of the central nervous system. The large heterogeneity of LD results from the diversity of the genetically determined defects that interfere with glial cells functions. Astrocytes have been identified as the primary target of LD with cystic myelin breakdown including those related to mutations in the ubiquitous translation initiation factor eIF2B. EIF2B is involved in global protein synthesis and its regulation under normal and stress conditions. Little is known about how eIF2B mutations have a major effect on WM. We performed a transcriptomic analysis using fibroblasts of 10 eIF2B-mutated patients with a severe phenotype and 10 age matched patients with other types of LD in comparison to control fibroblasts. ANOVA was used to identify genes that were statistically significantly differentially expressed at basal state and after ER-stress. The pattern of differentially expressed genes between basal state and ER-stress did not differ significantly among each of the three conditions. However, 70 genes were specifically differentially expressed in eIF2B-mutated fibroblasts whatever the stress conditions tested compared to controls, 96% being under-expressed. Most of these genes were involved in mRNA regulation and mitochondrial metabolism. The 13 most representative genes, including genes belonging to the Heterogeneous Nuclear Ribonucleoprotein (HNRNP) family, described as regulators of splicing events and stability of mRNA, were dysregulated during the development of eIF2B-mutated brains. HNRNPH1, F and C mRNA were over-expressed in foetus but under-expressed in children and adult brains. The abnormal regulation of HNRNP expression in the brain of eIF2B-mutated patients was concomitant with splicing dysregulation of the main genes involved in glial maturation such as PLP1 for oligodendrocytes and GFAP in astrocytes. These findings demonstrate a developmental deregulation of splicing events in glial cells that is related to abnormal production of HNRNP, in eIF2B-mutated brains.
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Affiliation(s)
- Aurélia Huyghe
- Génétique, Reproduction et Développement (GReD) Faculté de Médecine, Clermont-Ferrand, France
- Université de Clermont, UFR Médecine, Clermont-Ferrand, France
| | - Laetitia Horzinski
- Génétique, Reproduction et Développement (GReD) Faculté de Médecine, Clermont-Ferrand, France
- Université de Clermont, UFR Médecine, Clermont-Ferrand, France
| | - Alain Hénaut
- Systématique, Adaptation, Evolution, CNRS - Université Pierre et Marie Curie, Paris, France
| | - Marina Gaillard
- Génétique, Reproduction et Développement (GReD) Faculté de Médecine, Clermont-Ferrand, France
- Université de Clermont, UFR Médecine, Clermont-Ferrand, France
| | - Enrico Bertini
- Division of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Department of Neuroscience, Bambino Gesu’Hospital Instituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
| | - Raphael Schiffmann
- Institute of Metabolic Disease, Baylor Research Institute, Dallas, Texas, United States of America
| | - Diana Rodriguez
- Assistance Publique-Hôpitaux de Paris, Hôpital Armand Trousseau, Service de Neuropédiatrie, Paris, France
- INSERM U676, Hopital Robert Debré, Paris, France
- Université Pierre et Marie Curie, Paris, France
| | - Yann Dantal
- Soluscience, Faculté de Médecine, Clermont-Ferrand, France
| | - Odile Boespflug-Tanguy
- Génétique, Reproduction et Développement (GReD) Faculté de Médecine, Clermont-Ferrand, France
- INSERM U676, Hopital Robert Debré, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Service de Neuropédiatrie et Maladies Métaboliques, Paris, France
- Université Paris Diderot, Sorbonne Cité, Paris, France
| | - Anne Fogli
- Génétique, Reproduction et Développement (GReD) Faculté de Médecine, Clermont-Ferrand, France
- Université de Clermont, UFR Médecine, Clermont-Ferrand, France
- Centre Hospitalier Universitaire de Clermont-Ferrand, Service de Biochimie Médicale et Biologie Moléculaire, Clermont-Ferrand, France
- * E-mail:
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20
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Wang E, Cambi F. MicroRNA expression in mouse oligodendrocytes and regulation of proteolipid protein gene expression. J Neurosci Res 2012; 90:1701-12. [PMID: 22504928 DOI: 10.1002/jnr.23055] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/19/2012] [Accepted: 02/20/2012] [Indexed: 12/22/2022]
Abstract
Overexpression of the major myelin proteolipid protein (PLP) is detrimental to brain development and function and is the most common cause of Pelizaeus-Merzbacher disease. microRNA (miRNA), small, noncoding RNAs, have been shown to play critical roles in oligodendrocyte lineage. In this study, we sought to investigate whether miRNAs control PLP abundance. To identify candidate miRNAs involved in this regulation, we have examined differentiation-induced changes in the expression of miRNAs in the oligodendroglial cell line Oli-neu and in enhanced green fluorescent protein positive oligodendrocytes ex vivo. We have identified 145 miRNAs that are expressed in oligodendrocyte cell lineage progression. Dicer1 expression decreases in differentiated oligodendrocytes, and knock down of Dicer1 results in changes in miRNAs similar to those associated with differentiation. To identify miRNAs that control the PLP expression, we have selected miRNAs whose expression is lower in differentiated vs. undifferentiated Oli-neu cells and that have one or more binding site(s) in the PLP 3'-untranslated region (3'UTR). The PLP 3'UTR fused to the luciferase gene reduces the activity of the reporter, suggesting that it negatively regulates message stability or translation. Such suppression is relieved by knock down of miR-20a. Overexpression of miR-20a decreases expression of the endogenous PLP in primary oligodendrocytes and of the reporter gene. Deletion or mutation of the putative binding site for miR-20a in the PLP 3'UTR abrogated such effects. Our data indicate that miRNA expression is regulated by Dicer1 levels in differentiated oligodendrocytes and that miR-20a, a component of the cluster that controls oligodendrocyte cell number, regulates PLP gene expression through its 3'UTR.
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Affiliation(s)
- Erming Wang
- Department of Neurology, University of Kentucky, Lexington, Kentucky, USA.
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21
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Klopocki E, Mundlos S. Copy-number variations, noncoding sequences, and human phenotypes. Annu Rev Genomics Hum Genet 2011; 12:53-72. [PMID: 21756107 DOI: 10.1146/annurev-genom-082410-101404] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Whereas single-nucleotide polymorphisms and their role in predisposition to disease have been studied extensively, the analysis of structural variants--genomic changes such as insertions, deletions, inversions, duplications, and translocations--is still in its infancy. Changes in copy number, also known as copy-number variations (CNVs), constitute one such group of these structural variants. CNVs are structural genomic variants that arise from deletions (loss) or duplications (gain), and as a consequence result in a copy-number change of the respective genomic region. CNVs may include entire genes or regions of transcribed sequence, or, indeed, comprise only nontranscribed sequences. Whereas the duplication or deletion of a gene can be expected to have an effect on gene dosage, the consequences of CNVs in nontranscribed sequences are less obvious. Here we review CNVs that involve regulatory nontranscribed regions of the genome, describe the associated human phenotypes, and discuss possible disease mechanisms.
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Affiliation(s)
- Eva Klopocki
- Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany.
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22
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Zhu H, Zhao L, Wang E, Dimova N, Liu G, Feng Y, Cambi F. The QKI-PLP pathway controls SIRT2 abundance in CNS myelin. Glia 2011; 60:69-82. [PMID: 21948283 DOI: 10.1002/glia.21248] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 08/30/2011] [Indexed: 01/12/2023]
Abstract
Sirtuin 2 (SIRT2), a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase expressed by oligodendrocytes (OLs), the myelin-producing cells of the central nervous system (CNS), is markedly up-regulated during active myelination (Li et al. (2007) J Neurosci 27:2606-2616; Southwood et al. (2007) Neurochem Res 32:187-195; Werner et al. (2007) J Neurosci 27:7717-7730). SIRT2 is a component of the myelin proteome and is severely reduced in the Plp1 knockout mouse brain, in which both proteolipid protein (PLP) and DM20 are absent (Werner et al. (2007) J Neurosci 27:7717-7730). The mechanisms that regulate SIRT2 expression in OLs and myelin remain to be investigated. We report for the first time that the expression of SIRT2 is regulated by the QKI-dependent pathway and this effect is mediated through selective regulation of PLP. In the homozygous quakingviable (qk(v) /qk(v) ) mutant mouse that harbors QKI deficiency in OLs (Bockbrader and Feng (2008) Future Neurol 3:655-668; Ebersole et al. (1996) Nat Genet 12:260-265; Hardy et al. (1996) J Neurosci 16:7941-7949), PLP, but not DM20 mRNA, was selectively down-regulated and SIRT2 protein was severely reduced whereas SIRT2 mRNA expression was unaffected. Expression of the cytoplasmic isoform QKI6 in OLs (Zhao et al. (2006) J Neurosci 26:11278-11286) rescued SIRT2 expression in the qk(v) /qk(v) mutant concomitantly with restoration of PLP expression. Moreover, SIRT2 protein is diminished in myelin tracts and compact myelin of the PLP-ISEdel mutant brain, in which PLP protein but not DM20 is selectively reduced (Wang et al. (2008) Exp Neurol 214:322-330). In contrast, SIRT2 expression and its cellular function in regulating process complexity are not affected by the absence of PLP in PLP-ISEdel non-myelinating OLs. Collectively, our results indicate that the abundance of SIRT2 in myelin is dependent on PLP, but not DM20.
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Affiliation(s)
- H Zhu
- Department of Neurology, University of Kentucky, Lexington, Kentucky, USA
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23
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Wang E, Mueller WF, Hertel KJ, Cambi F. G Run-mediated recognition of proteolipid protein and DM20 5' splice sites by U1 small nuclear RNA is regulated by context and proximity to the splice site. J Biol Chem 2011; 286:4059-71. [PMID: 21127064 PMCID: PMC3039333 DOI: 10.1074/jbc.m110.199927] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Indexed: 11/06/2022] Open
Abstract
Highly conserved G runs, G1M2 and ISE, regulate the proteolipid protein (PLP)/DM20 ratio. We have investigated recruitment of U1 small nuclear ribonuclear protein (snRNP) by G1M2 and ISE and examined the effect of splice site strength, distance, and context on G run function. G1M2 is necessary for initial recruitment of U1snRNP to the DM20 5' splice site independent of the strength of the splice site. G1M2 regulates E complex formation and supports DM20 splicing when functional U1snRNP is reduced. By contrast, the ISE is not required for the initial recruitment of U1snRNP to the PLP 5' splice site. However, in close proximity to either the DM20 or the PLP 5' splice site, the ISE recruits U1snRNP to both splice sites. The ISE enhances DM20 splicing, whereas close to the PLP 5' splice site, it inhibits PLP splicing. Splicing enhancement and inhibition are mediated by heterogeneous nuclear ribonuclear protein (hnRNP)H/F. The data show that recognition of the DM20 5' splice site depends on G run-mediated recruitment of U1snRNA, whereas a complex interaction between the ISE G runs, context and position determines the functional outcome on splicing. The data suggest that different mechanisms underlie G run-mediated recognition of 5' splice sites and that context and position play a critical role.
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Affiliation(s)
- Erming Wang
- From the Department of Neurology, University of Kentucky, Lexington, Kentucky 40536 and
| | - William F. Mueller
- the Department of Microbiology and Molecular Genetics, University of California, Irvine, California 92697
| | - Klemens J. Hertel
- the Department of Microbiology and Molecular Genetics, University of California, Irvine, California 92697
| | - Franca Cambi
- From the Department of Neurology, University of Kentucky, Lexington, Kentucky 40536 and
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24
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Mutka AL, Haapanen A, Käkelä R, Lindfors M, Wright AK, Inkinen T, Hermansson M, Rokka A, Corthals G, Jauhiainen M, Gillingwater TH, Ikonen E, Tyynelä J. Murine cathepsin D deficiency is associated with dysmyelination/myelin disruption and accumulation of cholesteryl esters in the brain. J Neurochem 2009; 112:193-203. [PMID: 19845830 DOI: 10.1111/j.1471-4159.2009.06440.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cathepsin D (CTSD) deficiencies are fatal neurological diseases that in human infants and in sheep are characterized by extreme loss of neurons and myelin. To date, similar morphological evidence for myelin disruption in CTSD knockout mice has not been reported. Here, we show that CTSD deficiency leads to pronounced myelin changes in the murine brain: myelin-related proteolipid protein and myelin basic protein were both markedly reduced at postnatal day 24, and the amount of lipids characteristically high in myelin (e.g. plasmalogen-derived alkenyl chains and glycosphingolipid-derived 20- and 24-carbon acyl chains) were significantly lowered compared with controls. These changes were accompanied by ultrastructural alterations of myelin, including significant thinning of myelin sheaths. Furthermore, in CTSD knockout brains there was a pronounced accumulation of cholesteryl esters and abnormal levels of proteins related to cholesterol transport, with an increased content of apolipoprotein E and a reduced content of ATP-binding cassette transporter A1. These results provide evidence for dysmyelination and altered trafficking of cholesterol in brains of CTSD knockout mice, and warrant further studies on the role of lipid metabolism in the pathogenesis of CTSD deficiencies.
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Affiliation(s)
- Aino-Liisa Mutka
- Institute of Biomedicine/Anatomy, Biomedicum, University of Helsinki, Helsinki, Finland
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25
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PLP1 gene duplication causes overexpression and alteration of the PLP/DM20 splicing balance in fibroblasts from Pelizaeus–Merzbacher disease patients. Biochim Biophys Acta Mol Basis Dis 2009; 1792:548-54. [DOI: 10.1016/j.bbadis.2009.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 04/01/2009] [Accepted: 04/02/2009] [Indexed: 11/15/2022]
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26
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Wang E, Cambi F. Heterogeneous nuclear ribonucleoproteins H and F regulate the proteolipid protein/DM20 ratio by recruiting U1 small nuclear ribonucleoprotein through a complex array of G runs. J Biol Chem 2009; 284:11194-204. [PMID: 19244236 DOI: 10.1074/jbc.m809373200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In this study, we sought to investigate the mechanism by which heterogeneous nuclear ribonucleoprotein (hnRNP) H and F regulate proteolipid protein (PLP)/DM20 alternative splicing. G-rich sequences in exon 3B, G1 and M2, are required for hnRNPH- and F-mediated regulation of the PLP/DM20 ratio and, when placed between competing 5' splice sites in an alpha-globin minigene, direct hnRNPH/F-regulated alternative splicing. In contrast, the activity of the intronic splicing enhancer, which is necessary for PLP splicing, is only modestly reduced by removal of hnRNPH/F both in PLP and alpha-globin gene context. In vivo, hnRNPH reversed reduction of DM20 splicing induced by hnRNPH/F removal, whereas hnRNPF had little effect. Tethering of the MS2-hnRNPH fusion protein downstream of the DM20 5' splice site increased DM20 splicing, whereas MS2-hnRNPF did not. Binding of U1 small nuclear ribonucleoprotein (U1snRNP) to DM20 is greatly impaired by mutation of G1 and M2 and depletion of hnRNPH and F. Reconstitution of hnRNPH/F-depleted extracts with either hnRNPH or F restored U1snRNP binding. We conclude that hnRNPH and F regulate DM20 splicing by recruiting U1snRNP and that hnRNPH plays a primary role in DM20 splice site selection in vivo. Decreased expression of hnRNPH/F in differentiated oligodendrocytes may regulate the PLP/DM20 ratio by reducing DM20 5' splice site recognition by U1snRNP.
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Affiliation(s)
- Erming Wang
- Department of Neurology, University of Kentucky, Lexington, Kentucky 40536, USA
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27
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Wang E, Dimova N, Sperle K, Huang Z, Lock L, McCulloch MC, Edgar JM, Hobson GM, Cambi F. Deletion of a splicing enhancer disrupts PLP1/DM20 ratio and myelin stability. Exp Neurol 2008; 214:322-30. [DOI: 10.1016/j.expneurol.2008.09.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 08/21/2008] [Accepted: 09/02/2008] [Indexed: 11/30/2022]
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28
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Bonnet-Dupeyron MN, Combes P, Santander P, Cailloux F, Boespflug-Tanguy O, Vaurs-Barrière C. PLP1 splicing abnormalities identified in Pelizaeus-Merzbacher disease and SPG2 fibroblasts are associated with different types of mutations. Hum Mutat 2008; 29:1028-36. [PMID: 18470932 DOI: 10.1002/humu.20758] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The proteolipid protein 1 (PLP1) gene encodes the two major proteins of the central nervous system (CNS) myelin: PLP and DM20. PLP1 gene mutations are associated with a large spectrum of X-linked dysmyelinating disorders ranging from hypomyelinating leukodystrophy, Pelizaeus-Merzbacher disease (PMD), to spastic paraplegia (SPG2) according to the nature of the mutation. Genetic heterogeneity exists and mutations in the gap-junction alpha 12 (GJA12) gene have been related to PMD. About 20% of patients with the PMD phenotype remain without mutation in these two genes and are classified as affected by Pelizaeus-Merzbacher-like disease (PMLD). To study PLP1 splicing abnormalities, we analyzed PLP/DM20 transcripts from nerves and/or skin cultured fibroblasts of 14 PMD/SPG2 patients carrying different PLP1 mutations and 20 PMLD patients. We found that various types of PLP1 mutations result in missplicing, including one considered as a missense in exon 2 and a nucleotide substitution in intron 3 outside the classical donor and acceptor splicing sites. Moreover, we demonstrated for two patients that the fibroblast transcript pattern was in accordance with the one observed in the corresponding CNS/peripheral nervous system (PNS) tissues. Finally, we observed no abnormal splicing in fibroblasts of 20 PMLD patients tested; suggesting that PLP1 gene splicing abnormalities, potentially caused by undetected intronic mutations, are either not involved or are very rarely implicated in the PMLD phenotype. These results confirm that fibroblasts are reliable, accessible cells useful in detecting PLP1 transcript abnormalities, better characterizing the functional consequences of PLP1 mutations for genotype-phenotype correlation, characterizing new PLP1 splicing regulatory elements, and identifying PLP1 mutations undetected by conventional PLP1 screening.
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29
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Wang E, Dimova N, Cambi F. PLP/DM20 ratio is regulated by hnRNPH and F and a novel G-rich enhancer in oligodendrocytes. Nucleic Acids Res 2007; 35:4164-78. [PMID: 17567613 PMCID: PMC1919487 DOI: 10.1093/nar/gkm387] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Alternative splicing of competing 5′ splice sites is regulated by enhancers and silencers in the spliced exon. We have characterized sequences and splicing factors that regulate alternative splicing of PLP and DM20, myelin proteins produced by oligodendrocytes (OLs) by selection of 5′ splice sites in exon 3. We identify a G-rich enhancer (M2) of DM20 5′ splice site in exon 3B and show that individual G triplets forming M2 are functionally distinct and the distal group plays a dominant role. G-rich M2 and a G-rich splicing enhancer (ISE) in intron 3 share similarities in function and protein binding. The G-rich sequences are necessary for binding of hnRNPs to both enhancers. Reduction in hnRNPH and F expression in differentiated OLs correlates temporally with increased PLP/DM20 ratio. Knock down of hnRNPH increased PLP/DM20 ratio, while hnRNPF did not. Silencing hnRNPH and F increased the PLP/DM20 ratio more than hnRNPH alone, demonstrating a novel synergistic effect. Mutation of M2, but not ISE reduced the synergistic effect. Replacement of M2 and all G runs in exon 3B abolished it almost completely. We conclude that developmental changes in hnRNPH/F associated with OLs differentiation synergistically regulate PLP alternative splicing and a G-rich enhancer participates in the regulation.
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Affiliation(s)
| | | | - Franca Cambi
- *To whom Correspondence should be addressed. (859) 323 5683859 323 5943
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30
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Wolf NI, Cundall M, Rutland P, Rosser E, Surtees R, Benton S, Chong WK, Malcolm S, Ebinger F, Bitner-Glindzicz M, Woodward KJ. Frameshift mutation in GJA12 leading to nystagmus, spastic ataxia and CNS dys-/demyelination. Neurogenetics 2006; 8:39-44. [PMID: 16969684 DOI: 10.1007/s10048-006-0062-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 08/11/2006] [Indexed: 10/24/2022]
Abstract
Mutations in GJA12 have been shown to cause Pelizaeus-Merzbacher-like disease (PMLD). We present two additional patients from one family carrying a homozygous frameshift mutation in GJA12. Both presented initially with nystagmus. The older girl developed ataxia first, then progressive spastic ataxia. The younger boy suffered from severe sensory neuropathy. Magnetic resonance imaging (MRI) of both children showed progressive demyelination in addition to dysmyelination, and also characteristic brainstem abnormalities. In children with nystagmus, ataxia and dysmyelination, mutation analysis of GJA12 should be considered early, especially if inheritance is autosomal recessive.
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Affiliation(s)
- Nicole I Wolf
- Clinical and Molecular Genetics Unit, Institute of Child Health, London, UK.
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31
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Hurst S, Garbern J, Trepanier A, Gow A. Quantifying the carrier female phenotype in Pelizaeus-Merzbacher disease. Genet Med 2006; 8:371-8. [PMID: 16778599 DOI: 10.1097/01.gim.0000223551.95862.c3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Pelizaeus-Merzbacher disease and spastic paraplegia type 2 are allelic X-linked disorders that principally affect males and are caused by mutations in the proteolipid protein 1 gene. Neurologic symptoms are occasionally observed in carrier females, and anecdotal evidence suggests that these clinical signs are more likely in families with affected males. We analyze 40 pedigrees to determine whether such a link exists. METHODS From a chart review of patients from Wayne State University, we categorize patients according to disease severity and type of genetic lesion within the proteolipid protein 1 gene. We then analyze the clinical data using nonparametric t tests and analyses of variance. RESULTS Our analyses formally demonstrate the link between mild disease in males and symptoms in carrier female relatives. Conversely, mutations causing severe disease in males rarely cause clinical signs in carrier females. The greatest risk of disease in females is found for nonsense/indel or null mutations. Missense mutations carry moderate risk. The lowest risk, which represents the bulk of families with Pelizaeus-Merzbacher disease, is associated with proteolipid protein 1 gene duplications. CONCLUSIONS Effective genetic counseling of Pelizaeus-Merzbacher disease and spastic paraplegia carrier females must include an assessment of disease severity in affected male relatives.
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Affiliation(s)
- Stephanie Hurst
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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32
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Wang E, Huang Z, Hobson GM, Dimova N, Sperle K, McCullough A, Cambi F. PLP1 alternative splicing in differentiating oligodendrocytes: characterization of an exonic splicing enhancer. J Cell Biochem 2006; 97:999-1016. [PMID: 16288477 DOI: 10.1002/jcb.20692] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Proteolipid protein (PLP) and DM20 are generated by alternative splicing of exon 3B of PLP1 transcript in differentiating oligodendrocytes. We investigated the role of exonic splicing enhancers (ESE) in the selection of PLP 5' donor site, focusing on putative ASF/SF2, and SC35 binding motifs in exon 3B on the basis of mutations that cause disease in humans. Mutations in a putative ASF/SF2 binding motif (nucleotides 406-412) reduced PLP 5' donor site selection, whereas a mutation in a putative SC35 binding motif (nucleotides 382-389) had no effect. UV crosslinking and immunoprecipitation (IP) assays using an antibody to ASF/SF2 showed that the ASF/SF2 protein specifically binds to the ESE (nucleotides 406-412). The single nucleotide mutations that reduced PLP splice site selection greatly diminished ASF/SF2 protein binding to this motif. We next tested the effect of overexpressed ASF/SF2 on PLP 5'splice selection in differentiating oligodendrocytes. ASF/SF2 positively regulates PLP splice site selection in a concentration-dependent manner. Disruption of the putative ASF/SF2 binding site in exon 3B reduced the positive effect of ASF/SF2 on PLP splicing. We conclude that an ESE in exon3B regulates PLP 5' donor site selection and that ASF/SF2 protein participates in the regulation of PLP alternative splicing in oligodendrocytes.
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Affiliation(s)
- Erming Wang
- Department of Neurology, University of Kentucky, Lexington, Kentucky 40536-0284, USA
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33
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Královicová J, Vorechovsky I. Position-dependent repression and promotion of DQB1 intron 3 splicing by GGGG motifs. THE JOURNAL OF IMMUNOLOGY 2006; 176:2381-8. [PMID: 16455996 DOI: 10.4049/jimmunol.176.4.2381] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Alternative splicing of HLA-DQB1 exon 4 is allele-dependent and results in variable expression of soluble DQbeta. We have recently shown that differential inclusion of this exon in mature transcripts is largely due to intron 3 variants in the branch point sequence (BPS) and polypyrimidine tract. To identify additional regulatory cis-elements that contribute to haplotype-specific splicing of DQB1, we systematically examined the effect of guanosine (G) repeats on intron 3 removal. We found that the GGG or GGGG repeats generally improved splicing of DQB1 intron 3, except for those that were adjacent to the 5' splice site where they had the opposite effect. The most prominent splicing enhancement was conferred by GGGG motifs arranged in tandem upstream of the BPS. Replacement of a G-rich segment just 5' of the BPS with a series of random sequences markedly repressed splicing, whereas substitutions of a segment further upstream that lacked the G-rich elements and had the same size did not result in comparable splicing inhibition. Systematic mutagenesis of both suprabranch guanosine quadruplets (G(4)) revealed a key role of central G residues in splicing enhancement, whereas cytosines in these positions had the most prominent repressive effects. Together, these results show a significant role of tandem G(4)NG(4) structures in splicing of both complete and truncated DQB1 intron 3, support position dependency of G repeats in splicing promotion and inhibition, and identify positively and negatively acting sequences that contribute to the haplotype-specific DQB1 expression.
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Affiliation(s)
- Jana Královicová
- Division of Human Genetics, University of Southampton, School of Medicine, UK
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34
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Sironi M, Menozzi G, Comi GP, Cagliani R, Bresolin N, Pozzoli U. Analysis of intronic conserved elements indicates that functional complexity might represent a major source of negative selection on non-coding sequences. Hum Mol Genet 2005; 14:2533-46. [PMID: 16037065 DOI: 10.1093/hmg/ddi257] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The non-coding portion of human genome is punctuated by a large number of multispecies conserved sequence (MCS) elements with largely unknown function. We demonstrate that MCSs are unevenly distributed in human introns with the majority of relatively short introns (< 9 kb long) displaying no or a few MCSs and that MCS density reaching up to 10% of total size in longer introns. After correction for intron length, MCSs were found to be enriched within genes involved in development and transcription, whereas depleted in immune response loci. Moreover, many central nervous system tissues show a preferential expression of MCS-rich genes and MCS enrichment significantly correlates with gene functional complexity in terms of distinct protein domains. Analysis of human-mouse orthologous pairs indicated a significant association between intronic MCS density and conservation of protein sequence, promoter regions and untranslated sequences. Moreover, MCS density correlates with the predicted occurrence of human-mouse conserved alternative splicing events. These observations suggest that evolution acts on human genes as integrated units of coding and regulatory capacity and that functional complexity might represent a major source of negative selection on non-coding sequences. To substantiate our result, we also searched previously experimentally identified intronic regulatory elements and indicate that about half of these sequences map to an MCS; in particular, support to the notion whereby mutations in MCSs can result in human genetic diseases is provided, because three previously identified intronic pathological variations were found to occur within MCSs, and human disease and cancer genes were found significantly enriched in MCSs.
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Affiliation(s)
- Manuela Sironi
- Scientific Institute IRCCS E. Medea, 23842 Bosisio Parini (LC), Italy
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35
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Hobson GM, Huang Z, Sperle K, Sistermans E, Rogan PK, Garbern JY, Kolodny E, Naidu S, Cambi F. Splice-site contribution in alternative splicing ofPLP1 andDM20: molecular studies in oligodendrocytes. Hum Mutat 2005; 27:69-77. [PMID: 16287154 DOI: 10.1002/humu.20276] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mutations in the proteolipid protein 1 (PLP1) gene cause the X-linked dysmyelinating diseases Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia 2 (SPG2). We examined the severity of the following mutations that were suspected of affecting levels of PLP1 and DM20 RNA, the alternatively spliced products of PLP1: c.453G>A, c.453G>T, c.453G>C, c.453+2T>C, c.453+4A>G, c.347C>A, and c.453+28_+46del (the old nomenclature did not include the methionine codon: G450A, G450T, G450C, IVS3+2T>C, IVS3+4A>G, C344A, and IVS3+28-+46del). These mutations were evaluated by information theory-based analysis and compared with mRNA expression of the alternatively spliced products. The results are discussed relative to the clinical severity of disease. We conclude that the observed PLP1 and DM20 splicing patterns correlated well with predictions of information theory-based analysis, and that the relative strength of the PLP1 and DM20 donor splice sites plays an important role in PLP1 alternative splicing.
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Affiliation(s)
- Grace M Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Nemours Children's Clinic, Wilmington, Delaware, USA.
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36
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Inoue K. PLP1-related inherited dysmyelinating disorders: Pelizaeus-Merzbacher disease and spastic paraplegia type 2. Neurogenetics 2004; 6:1-16. [PMID: 15627202 DOI: 10.1007/s10048-004-0207-y] [Citation(s) in RCA: 205] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 11/17/2004] [Indexed: 10/26/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) and its allelic disorder, spastic paraplegia type 2 (SPG2), are among the best-characterized dysmyelinating leukodystrophies of the central nervous system (CNS). Both PMD and SPG2 are caused by mutations in the proteolipid protein 1 (PLP1) gene, which encodes a major component of CNS myelin proteins. Distinct types of mutations, including point mutations and genomic duplications and deletions, have been identified as causes of PMD/SPG2 that act through different molecular mechanisms. Studies of various PLP1 mutants in humans and animal models have shed light on the genomic, molecular, and cellular pathogeneses of PMD/SPG2. Recent discoveries include complex mutational mechanisms and associated disease phenotypes, novel cellular pathways that lead to the degeneration of oligodendrocytes, and genomic architectural features that result in unique chromosomal rearrangements. Here, I review the previous and current knowledge of the molecular pathogenesis of PMD/SPG2 and delineate future directions for PMD/SPG2 studies.
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Affiliation(s)
- Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan.
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37
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Abstract
BACKGROUND An objective demonstration of lesions disseminated in time and space remains the core of the last revision of diagnostic criteria for multiple sclerosis (MS), but this update is now empowered by a weighted use of magnetic resonance imaging (MRI), which results in an earlier and more unambiguous diagnosis ("MS," "not MS," or "possible MS"). Nevertheless, the exclusion of other entities still remains an integral element of the diagnostic process. REVIEW SUMMARY Exclusion of genetic disorders can be challenging in some cases with familial recurrence of MS, particularly when the transmission is mimicking a mendelian or a maternal pattern of inheritance. Vice versa, many forms of mendelian leukodystrophies and leukoencephalopathies present with juvenile or adult onset, progressive or relapsing-remitting courses, intrafamilial phenotypic heterogeneity and MRI signs of multifocal white matter (WM) pathology, features potentially leading to a temporary confusion with MS. With the recent availability of disease modifying medications in MS, the development of specific molecular therapies in inherited WM disorders, and the general recognition of the effectiveness of early treatments, the accuracy of initial diagnostic assessment has become critical. CONCLUSION Considering the importance of disease specific treatments, here we review the major characteristics of familial MS and some of the inheritable diseases of the WM. Although no direct genetic link between MS and these WM abnormalities is known, molecular data from the field of rare genetic disorders may also provide some experimental paradigms to a further exploration of MS.
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Affiliation(s)
- Bernadette Kalman
- Department of Neurology, MS Research Center, SLRHC, Columbia University, New York, NY 10019, USA.
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38
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Shy ME, Hobson G, Jain M, Boespflug-Tanguy O, Garbern J, Sperle K, Li W, Gow A, Rodriguez D, Bertini E, Mancias P, Krajewski K, Lewis R, Kamholz J. Schwann cell expression of PLP1 but not DM20 is necessary to prevent neuropathy. Ann Neurol 2003; 53:354-65. [PMID: 12601703 PMCID: PMC4744322 DOI: 10.1002/ana.10466] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Proteolipid protein (PLP1) and its alternatively spliced isoform, DM20, are the major myelin proteins in the CNS, but are also expressed in the PNS. The proteins have an identical sequence except for 35 amino acids in PLP1 (the PLP1-specific domain) not present in DM20. Mutations of PLP1/DM20 cause Pelizaeus-Merzbacher Disease (PMD), a leukodystrophy, and in some instances, a peripheral neuropathy. To identify which mutations cause neuropathy, we have evaluated a cohort of patients with PMD and PLP1 mutations for the presence of neuropathy. As shown previously, all patients with PLP1 null mutations had peripheral neuropathy. We also identified 4 new PLP1 point mutations that cause both PMD and peripheral neuropathy, three of which truncate PLP1 expression within the PLP1-specific domain, but do not alter DM20. The fourth, a splicing mutation, alters both PLP1 and DM20, and is probably a null mutation. Six PLP1 point mutations predicted to produce proteins with an intact PLP1-specific domain do not cause peripheral neuropathy. Sixty-one individuals with PLP1 duplications also had normal peripheral nerve function. These data demonstrate that expression of PLP1 but not DMSO is necessary to prevent neuropathy, and suggest that the 35 amino acid PLP1-specific domain plays an important role in normal peripheral nerve function.
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Affiliation(s)
- Michael E Shy
- Department of Neurology and Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
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