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Khalaf G, Mattern C, Begou M, Boespflug-Tanguy O, Massaad C, Massaad-Massade L. Mutation of Proteolipid Protein 1 Gene: From Severe Hypomyelinating Leukodystrophy to Inherited Spastic Paraplegia. Biomedicines 2022; 10:biomedicines10071709. [PMID: 35885014 PMCID: PMC9313024 DOI: 10.3390/biomedicines10071709] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/06/2022] [Accepted: 07/12/2022] [Indexed: 01/17/2023] Open
Abstract
Pelizaeus–Merzbacher Disease (PMD) is an inherited leukodystrophy affecting the central nervous system (CNS)—a rare disorder that especially concerns males. Its estimated prevalence is 1.45–1.9 per 100,000 individuals in the general population. Patients affected by PMD exhibit a drastic reduction or absence of myelin sheaths in the white matter areas of the CNS. The Proteolipid Protein 1 (PLP1) gene encodes a transmembrane proteolipid protein. PLP1 is the major protein of myelin, and it plays a key role in the compaction, stabilization, and maintenance of myelin sheaths. Its function is predominant in oligodendrocyte development and axonal survival. Mutations in the PLP1 gene cause the development of a wide continuum spectrum of leukopathies from the most severe form of PMD for whom patients exhibit severe CNS hypomyelination to the relatively mild late-onset type 2 spastic paraplegia, leading to the concept of PLP1-related disorders. The genetic diversity and the biochemical complexity, along with other aspects of PMD, are discussed to reveal the obstacles that hinder the development of treatments. This review aims to provide a clinical and mechanistic overview of this spectrum of rare diseases.
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Affiliation(s)
- Guy Khalaf
- U1195 Diseases and Hormones of the Nervous System, INSERM and Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France;
| | | | - Mélina Begou
- Neuro-Dol, CNRS, Inserm, Université Clermont Auvergne, 63000 Clermont-Ferrand, France;
| | - Odile Boespflug-Tanguy
- UMR 1141, INSERM, NeuroDiderot Université Paris Cité and APH-P, Neuropédiatrie, French Reference Center for Leukodystrophies, LEUKOFRANCE, Hôpital Robert Debré, 75019 Paris, France;
| | - Charbel Massaad
- UMRS 1124, INSERM, Université Paris Cité, 75006 Paris, France
- Correspondence: (C.M.); (L.M.-M.);Tel.: +33-1-49-59-18-30 (L.M.-M.)
| | - Liliane Massaad-Massade
- U1195 Diseases and Hormones of the Nervous System, INSERM and Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France;
- Correspondence: (C.M.); (L.M.-M.);Tel.: +33-1-49-59-18-30 (L.M.-M.)
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Qi Y, Montague P, Loney C, Campbell C, Shafie INF, Anderson TJ, McLaughlin M. In vitro evidence consistent with an interaction between wild-type and mutant SOD1 protein associated with canine degenerative myelopathy. Eur J Neurosci 2019; 50:3896-3905. [PMID: 31336405 DOI: 10.1111/ejn.14526] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/26/2019] [Accepted: 07/10/2019] [Indexed: 12/13/2022]
Abstract
Canine degenerative myelopathy (DM) is a progressive neurological disorder that may be considered to be a large animal model for specific forms of the fatal human disease, familial amyotrophic lateral sclerosis (fALS). DM is associated with a c118G>A mutation of the superoxide dismutase 1 (Sod1) gene, and a significant proportion of cases are inherited in an autosomal recessive manner in contrast to the largely, but not exclusively, dominant mode of inheritance in fALS. The consensus view is that these Sod1/SOD1 mutations result in a toxic gain of function but the mechanisms remain unclear. Here we used an in vitro neuroblastoma cell line transfection system to monitor wild-type and mutant forms of SOD1 fusion proteins containing either a Cherry or an enhanced green fluorescent protein (EGFP) tag. These fusion proteins retained SOD1 enzymatic activity on a native gel assay system. We demonstrate that SOD1 aggregate density is significantly higher in DM transfectants compared to wild-type. In addition, we show by co-immunoprecipitation and confocal microscopy, evidence for a potential interaction between wild-type and mutant forms of SOD1 in co-transfected cells. While in vitro studies have shown SOD1 heterodimer formation in fALS models, this is the first report for DM SOD1. Therefore, despite for the majority of cases there is a difference in the mode of inheritance between fALS and DM, a similar interaction between wild-type and mutant SOD1 forms can occur. Clarifying the role of SOD1 in DM may also be of benefit to understanding the role of SOD1 in fALS.
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Affiliation(s)
- Yao Qi
- School of Veterinary Medicine, College of Medical, Veterinary and Life Science, University of Glasgow, Scotland, UK
| | - Paul Montague
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Science (MVLS), University of Glasgow, Glasgow, UK
| | - Colin Loney
- MRC, Centre for Virus Research, MVLS, University of Glasgow, Glasgow, UK
| | - Clare Campbell
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Science (MVLS), University of Glasgow, Glasgow, UK
| | - Intan N F Shafie
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, University Putra Malaysia, Serdang, Malaysia
| | - Thomas J Anderson
- School of Veterinary Medicine, College of Medical, Veterinary and Life Science, University of Glasgow, Scotland, UK
| | - Mark McLaughlin
- School of Veterinary Medicine, College of Medical, Veterinary and Life Science, University of Glasgow, Scotland, UK
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Hypomyelinating disorders in China: The clinical and genetic heterogeneity in 119 patients. PLoS One 2018; 13:e0188869. [PMID: 29451896 PMCID: PMC5815574 DOI: 10.1371/journal.pone.0188869] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 11/14/2017] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE Hypomyelinating disorders are a group of clinically and genetically heterogeneous diseases characterized by neurological deterioration with hypomyelination visible on brain MRI scans. This study was aimed to clarify the clinical and genetic features of HMDs in Chinese population. METHODS 119 patients with hypomyelinating disorders in Chinese population were enrolled and evaluated based on their history, clinical manifestation, laboratory examinations, series of brain MRI with follow-up, genetic etiological tests including chromosomal analysis, multiplex ligation probe amplification, Sanger sequencing, targeted enrichment-based next-generation sequencing and whole exome sequencing. RESULTS Clinical and genetic features of hypomyelinating disorders were revealed. Nine different hypomyelinating disorders were identified in 119 patients: Pelizaeus-Merzbacher disease (94, 79%), Pelizaeus-Merzbacher-like disease (10, 8%), hypomyelination with atrophy of the basal ganglia and cerebellum (3, 3%), GM1 gangliosidosis (5, 4%), GM2 gangliosidosis (3, 3%), trichothiodystrophy (1, 1%), Pol III-related leukodystrophy (1, 1%), hypomyelinating leukodystrophy type 9 (1, 1%), and chromosome 18q deletion syndrome (1, 1%). Of the sample, 94% (112/119) of the patients were genetically diagnosed, including 111 with mutations distributing across 9 genes including PLP1, GJC2, TUBB4A, GLB1, HEXA, HEXB, ERCC2, POLR3A, and RARS and 1 with mosaic chromosomal change of 46, XX,del(18)(q21.3)/46,XX,r(18)(p11.32q21.3)/45,XX,-18. Eighteen novel mutations were discovered. Mutations in POLR3A and RARS were first identified in Chinese patients with Pol III-related leukodystrophy and hypomyelinating leukodystrophy, respectively. SIGNIFICANCE This is the first report on clinical and genetic features of hypomyelinating disorders with a large sample of patients in Chinese population, identifying 18 novel mutations especially mutations in POLR3A and RARS in Chinese patients, expanding clinical and genetic spectrums of hypomyelinating disorders.
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Zamanzadeh Z, Ataei M, Nabavi SM, Ahangari G, Sadeghi M, Sanati MH. In Silico Perspectives on the Prediction of the PLP's Epitopes involved in Multiple Sclerosis. IRANIAN JOURNAL OF BIOTECHNOLOGY 2017; 15:10-21. [PMID: 28959348 PMCID: PMC5582249 DOI: 10.15171/ijb.1356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 05/29/2016] [Accepted: 03/13/2017] [Indexed: 12/28/2022]
Abstract
BACKGROUND Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system (CNS). The main cause of the MS is yet to be revealed, but the most probable theory is based on the molecular mimicry that concludes some infections in the activation of T cells against brain auto-antigens that initiate the disease cascade. OBJECTIVES The Purpose of this research is the prediction of the auto-antigen potency of the myelin proteolipid protein (PLP) in multiple sclerosis. MATERIALS AND METHODS As there wasn't any tertiary structure of PLP available in the Protein Data Bank (PDB) and in order to characterize the structural properties of the protein, we modeled this protein using prediction servers. Meta prediction method, as a new perspective in silico, was performed to fi nd PLPs epitopes. For this purpose, several T cell epitope prediction web servers were used to predict PLPs epitopes against Human Leukocyte Antigens (HLA). The overlap regions, as were predicted by most web servers were selected as immunogenic epitopes and were subjected to the BLASTP against microorganisms. RESULTS Three common regions, AA58-74, AA161-177, and AA238-254 were detected as immunodominant regions through meta-prediction. Investigating peptides with more than 50% similarity to that of candidate epitope AA58-74 in bacteria showed a similar peptide in bacteria (mainly consistent with that of clostridium and mycobacterium) and spike protein of Alphacoronavirus 1, Canine coronavirus, and Feline coronavirus. These results suggest that cross reaction of the immune system to PLP may have originated from a bacteria or viral infection, and therefore molecular mimicry might have an important role in the progression of MS. CONCLUSIONS Through reliable and accurate prediction of the consensus epitopes, it is not necessary to synthesize all PLP fragments and examine their immunogenicity experimentally (in vitro). In this study, the best encephalitogenic antigens were predicted based on bioinformatics tools that may provide reliable results for researches in a shorter time and at a lower cost.
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Affiliation(s)
- Zahra Zamanzadeh
- Department of medical biotechnology. Institute of Medical Genetic, National Institute of Genetics Engineering and Biotechnology (NIGEB), Tehran, 14965/161 Iran
| | - Mitra Ataei
- Department of medical biotechnology. Institute of Medical Genetic, National Institute of Genetics Engineering and Biotechnology (NIGEB), Tehran, 14965/161 Iran
| | - Seyed Massood Nabavi
- Department of Neurology, Faculty of Public Health, Shahed University, Tehran, 18155/159, Iran
| | - Ghasem Ahangari
- Department of medical biotechnology. Institute of Medical Genetic, National Institute of Genetics Engineering and Biotechnology (NIGEB), Tehran, 14965/161 Iran
| | - Mehdi Sadeghi
- Department of medical biotechnology. Institute of Medical Genetic, National Institute of Genetics Engineering and Biotechnology (NIGEB), Tehran, 14965/161 Iran
| | - Mohammad Hosein Sanati
- Department of medical biotechnology. Institute of Medical Genetic, National Institute of Genetics Engineering and Biotechnology (NIGEB), Tehran, 14965/161 Iran
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Gruenenfelder FI, Thomson G, Penderis J, Edgar JM. Axon-glial interaction in the CNS: what we have learned from mouse models of Pelizaeus-Merzbacher disease. J Anat 2011; 219:33-43. [PMID: 21401588 DOI: 10.1111/j.1469-7580.2011.01363.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
In the central nervous system (CNS) the majority of axons are surrounded by a myelin sheath, which is produced by oligodendrocytes. Myelin is a lipid-rich insulating material that facilitates the rapid conduction of electrical impulses along the myelinated nerve fibre. Proteolipid protein and its isoform DM20 constitute the most abundant protein component of CNS myelin. Mutations in the PLP1 gene encoding these myelin proteins cause Pelizaeus-Merzbacher disease and the related allelic disorder, spastic paraplegia type 2. Animal models of these diseases, particularly models lacking or overexpressing Plp1, have shed light on the interplay between axons and oligodendrocytes, and how one component influences the other.
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Affiliation(s)
- Fredrik I Gruenenfelder
- Applied Neurobiology Group, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Scotland, UK
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Geva M, Cabilly Y, Assaf Y, Mindroul N, Marom L, Raini G, Pinchasi D, Elroy-Stein O. A mouse model for eukaryotic translation initiation factor 2B-leucodystrophy reveals abnormal development of brain white matter. ACTA ACUST UNITED AC 2010; 133:2448-61. [PMID: 20826436 DOI: 10.1093/brain/awq180] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Eukaryotic translation initiation factor 2B is a major housekeeping complex that governs the rate of global protein synthesis under normal and stress conditions. Mutations in any of its five subunits lead to leucoencephalopathy with vanishing white matter, an inherited chronic-progressive fatal brain disease with unknown aetiology, which is among the most prevalent childhood white matter disorders. We generated the first animal model for the disease by introducing a point mutation into the mouse Eif2b5 gene locus, leading to R132H replacement corresponding to the clinically significant human R136H mutation in the catalytic subunit. In contrast to human patients, mice homozygous for the mutant Eif2b5 allele (Eif2b5(R132H/R132H) mice) enable multiple analyses under a defined genetic background during the pre-symptomatic stages and during recovery from a defined brain insult. Time-course magnetic resonance imaging revealed for the first time the delayed development of the brain white matter due to the mutation. Electron microscopy demonstrated a higher proportion of small-calibre nerve fibres. Immunohistochemistry detected an abnormal abundance of oligodendrocytes and astrocytes in the brain of younger animals, as well as an abnormal level of major myelin proteins. Most importantly, mutant mice failed to recover from cuprizone-induced demyelination, reflecting an increased sensitivity to brain insults. The anomalous development of white matter in Eif2b5(R132H/R132H) mice underscores the importance of tight translational control to normal myelin formation and maintenance.
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Affiliation(s)
- Michal Geva
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
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Ng DP, Deber CM. Modulation of the oligomerization of myelin proteolipid protein by transmembrane helix interaction motifs. Biochemistry 2010; 49:6896-902. [PMID: 20695528 DOI: 10.1021/bi100739r] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Proteolipid protein (PLP) is a highly hydrophobic 276-residue integral membrane protein that constitutes more than 50% of the total protein in central nervous system myelin. Previous studies have shown that this protein exists in myelin as an oligomer rather than as a monomer, and mutations in PLP that lead to neurological disorders such as Pelizaeus-Merzbacher disease and spastic paraplegia type 2 have been reported to affect its normal oligomerization. Here we employ peptide-based and in vivo approaches to examine the role of the TM domain in the formation of PLP quaternary structure through homo-oligomeric helix-helix interactions. Focusing on the TM4 alpha-helix (sequence (239)FIAAFVGAAATLVSLLTFMIAATY(262)), the site of several disease-causing point mutations that involve putative small residue helix-helix interaction motifs in the TM4 sequence, we used SDS-PAGE, fluorescence resonance energy transfer, size-exclusion chromatography, and TOXCAT assays in an Escherichia coli membrane to show that the PLP TM4 helix readily assembles into varying oligomeric states. In addition, through targeted studies of the PLP TM4 alpha-helix with point mutations that selectively eliminate these small residue motifs via substitution of Gly, Ala, or Ser residues with Ile residues, we describe a potential mechanism through which disease-causing point mutations can lead to aberrant PLP assembly. The overall results suggest that TM segments in misfolded PLP monomers that expose and/or create surface-exposed helix-helix interaction sites that are normally masked may have consequences for disease.
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Affiliation(s)
- Derek P Ng
- Division of Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Thomson CE, McCulloch M, Sorenson A, Barnett SC, Seed BV, Griffiths IR, McLaughlin M. Myelinated, synapsing cultures of murine spinal cord--validation as an in vitro model of the central nervous system. Eur J Neurosci 2008; 28:1518-35. [PMID: 18793322 PMCID: PMC2777255 DOI: 10.1111/j.1460-9568.2008.06415.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Research in central nervous system (CNS) biology and pathology requires in vitro models, which, to recapitulate the CNS in vivo, must have extensive myelin and synapse formation under serum-free (defined) conditions. However, finding such a model has proven difficult. The technique described here produces dense cultures of myelinated axons, with abundant synapses and nodes of Ranvier, that are suitable for both morphological and biochemical analysis. Cellular and molecular events were easily visualised using conventional microscopy. Ultrastructurally, myelin sheaths were of the appropriate thickness relative to axonal diameter (G-ratio). Production of myelinated axons in these cultures was consistent and repeatable, as shown by statistical analysis of multiple experimental repeats. Myelinated axons were so abundant that from one litter of embryonic mice, myelin was produced in amounts sufficient for bulk biochemical analysis. This culture method was assessed for its ability to generate an in vitro model of the CNS that could be used for both neurobiological and neuropathological research. Myelin protein kinetics were investigated using a myelin fraction isolated from the cultures. This fraction was found to be superior, quantitatively and qualitatively, to the fraction recovered from standard cultures of dissociated oligodendrocytes, or from brain slices. The model was also used to investigate the roles of specific molecules in the pathogenesis of inflammatory CNS diseases. Using the defined conditions offered by this culture system, dose-specific, inhibitory effects of inflammatory cytokines on myelin formation were demonstrated, unequivocally. The method is technically quick, easy and reliable, and should have wide application to CNS research.
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Affiliation(s)
- C E Thomson
- Comparative Anatomy and Physiology, Institute of Veterinary, Biomedical and Animal Sciences, Massey University, Palmerston North, New Zealand.
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Southwood C, Olson K, Wu CY, Gow A. Novel alternatively spliced endoplasmic reticulum retention signal in the cytoplasmic loop of Proteolipid Protein-1. J Neurosci Res 2007; 85:471-8. [PMID: 17171701 PMCID: PMC4606141 DOI: 10.1002/jnr.21153] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Increased awareness about the importance of protein folding and trafficking to the etiology of gain-of-function diseases has driven extensive efforts to understand the cell and molecular biology underlying the life cycle of normal secretory pathway proteins and the detrimental effects of abnormal proteins. In this regard, the quality-control machinery in the endoplasmic reticulum (ER) has emerged as a major mechanism by which cells ensure that secreted and transmembrane proteins either adopt stable secondary, tertiary, and quaternary structures or are retained in the ER and degraded. Here we examine cellular and molecular aspects of ER retention in transfected fibroblasts expressing missense mutations in the Proteolipid Protein-1 (PLP1) gene that cause mild or severe forms of neurodegenerative disease in humans. Mild mutations cause protein retention in the ER that is partially dependent on the presence of a cytoplasmically exposed heptapeptide, KGRGSRG. In contrast, retention associated with severe mutations occurs independently of this peptide. Accordingly, the function of this novel heptapeptide has a significant impact on pathogenesis and provides new insight into the functions of the two splice isoforms encoded by the PLP1 gene, PLP1 and DM-20.
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Affiliation(s)
- Cherie Southwood
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan
| | - Kevin Olson
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan
| | - Chia-Yen Wu
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan
| | - Alexander Gow
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan
- Carman and Ann Adams Department of Pediatrics, Wayne State University School of Medicine, Detroit, Michigan
- Department of Neurology, Wayne State University School of Medicine, Detroit, Michigan
- Correspondence to: Dr. Alexander Gow, Center for Molecular Medicine and Genetics, 3216 Scott Hall, 540 E. Canfield Ave, Wayne State University School of Medicine, Detroit, MI 48201.
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McLaughlin M, Barrie JA, Karim S, Montague P, Edgar JM, Kirkham D, Thomson CE, Griffiths IR. Processing of PLP in a model of Pelizaeus-Merzbacher disease/SPG2 due to the rumpshaker mutation. Glia 2006; 53:715-22. [PMID: 16506223 DOI: 10.1002/glia.20325] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The rumpshaker mutation of the X-linked myelin proteolipid protein (PLP1) gene causes spastic paraplegia type 2 or a mild form of Pelizaeus-Merzbacher disease in man. The identical mutation occurs spontaneously in mice. Both human and murine diseases are associated with dysmyelination. Using the mouse model, we show that the low steady state levels of PLP result from accelerated proteasomal degradation rather than decreased synthesis. The T(1/2) for degradation of rumpshaker PLP is 11 h compared with 23 h for wild type. A minority of newly synthesized PLP is incorporated into myelin in the correct orientation but at a reduced rate compared with wild type. However, inhibition of proteasomal degradation does not increase the level of PLP incorporated into myelin. As Plp null mice do not have a similar myelin deficiency, it is unlikely that the reduced PLP levels are the main cause of the dysmyelination. Rumpshaker oligodendrocytes also have a reduced level of other myelin proteins, such as MBP, although the mechanisms are not yet defined but are likely to operate at a translational or post-translational level.
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Affiliation(s)
- Mark McLaughlin
- Applied Neurobiology Group, Institute of Comparative Medicine, University of Glasgow, Bearsden Glasgow G61 1QH, Scotland
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Schweitzer J, Becker T, Schachner M, Nave KA, Werner H. Evolution of myelin proteolipid proteins: Gene duplication in teleosts and expression pattern divergence. Mol Cell Neurosci 2006; 31:161-77. [PMID: 16289898 DOI: 10.1016/j.mcn.2005.10.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Revised: 09/30/2005] [Accepted: 10/12/2005] [Indexed: 11/26/2022] Open
Abstract
The coevolution of neurons and their supporting glia to the highly specialized axon-myelin unit included the recruitment of proteolipids as neuronal glycoproteins (DMbeta, DMgamma) or myelin proteins (DMalpha/PLP/DM20). Consistent with a genome duplication at the root of teleosts, we identified three proteolipid pairs in zebrafish, termed DMalpha1 and DMalpha2, DMbeta1 and DMbeta2, DMgamma1 and DMgamma2. The paralogous amino acid sequences diverged remarkably after gene duplication, indicating functional specialization. Each proteolipid has adopted a distinct spatio-temporal expression pattern in neural progenitors, neurons, and in glia. DMalpha2, the closest homolog to mammalian PLP/DM20, is coexpressed with P0 in oligodendrocytes and upregulated after optic nerve lesion. DMgamma2 is expressed in multipotential stem cells, and the other four proteolipids are confined to subsets of CNS neurons. Comparing protein sequences and gene structures from birds, teleosts, one urochordate species, and four invertebrates, we have reconstructed major steps in the evolution of proteolipids.
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Affiliation(s)
- Jörn Schweitzer
- Zentrum fuer Molekulare Neurobiologie, University of Hamburg, D-20251 Hamburg, Germany
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