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Jiang CQ, Hu J, Xiang JP, Zhu JK, Liu XL, Luo P. Tissue-engineered rhesus monkey nerve grafts for the repair of long ulnar nerve defects: similar outcomes to autologous nerve grafts. Neural Regen Res 2016; 11:1845-1850. [PMID: 28123431 PMCID: PMC5204243 DOI: 10.4103/1673-5374.194757] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Acellular nerve allografts can help preserve normal nerve structure and extracellular matrix composition. These allografts have low immunogenicity and are more readily available than autologous nerves for the repair of long-segment peripheral nerve defects. In this study, we repaired a 40-mm ulnar nerve defect in rhesus monkeys with tissue-engineered peripheral nerve, and compared the outcome with that of autograft. The graft was prepared using a chemical extract from adult rhesus monkeys and seeded with allogeneic Schwann cells. Pathomorphology, electromyogram and immunohistochemistry findings revealed the absence of palmar erosion or ulcers, and that the morphology and elasticity of the hypothenar eminence were normal 5 months postoperatively. There were no significant differences in the mean peak compound muscle action potential, the mean nerve conduction velocity, or the number of neurofilaments between the experimental and control groups. However, outcome was significantly better in the experimental group than in the blank group. These findings suggest that chemically extracted allogeneic nerve seeded with autologous Schwann cells can repair 40-mm ulnar nerve defects in the rhesus monkey. The outcomes are similar to those obtained with autologous nerve graft.
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Affiliation(s)
- Chang-Qing Jiang
- Department of Sports Medicine and Rehabilitation, Peking Universtiy Shenzhen Hospital, Shenzhen, Guangdong Province, China
| | - Jun Hu
- Department of Microscopy, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Jian-Ping Xiang
- Department of Microscopy, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Jia-Kai Zhu
- Department of Microscopy, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Xiao-Lin Liu
- Department of Microscopy, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Peng Luo
- The Sixth People's Hospital of Shenzhen City, Shenzhen, Guangdong Province, China
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2
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Frank SM, Denaro FJ. Peripheral Nerve Teasing: Two Protocols for Diagnosis and Research. J Histotechnol 2013. [DOI: 10.1179/his.1998.21.1.39] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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3
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NIEMANN STEPHAN, SEREDA MICHAELW, ROSSNER MORITZ, STEWART HELEN, SUTER UELI, MEINCK HANSMICHAEL, GRIFFITHS IANR, NAVE KLAUSARMIN. The “CMT Rat”: Peripheral Neuropathy and Dysmyelination Caused by Transgenic Overexpression ofPMP22. Ann N Y Acad Sci 2006; 883:254-261. [DOI: 10.1111/j.1749-6632.1999.tb08587.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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SNIPES GJACKSON, ORFALI WAYEL, FRASER ANDREW, DICKSON KATHLEEN, COLBY JOSHUA. The Anatomy and Cell Biology of Peripheral Myelin Protein-22. Ann N Y Acad Sci 2006; 883:143-151. [DOI: 10.1111/j.1749-6632.1999.tb08577.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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5
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Edgar JM, Garbern J. The myelinated axon is dependent on the myelinating cell for support and maintenance: molecules involved. J Neurosci Res 2004; 76:593-8. [PMID: 15139018 DOI: 10.1002/jnr.20063] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The myelin-forming cells, oligodendrocytes and Schwann cells, extend processes that spirally wrap axons and provide the insulation that allows rapid saltatory conduction. Recent data suggest a further role for the myelin-forming cells in axonal support and maintenance. This Mini-Review summarises some of the data that support this view and highlights the molecules involved.
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Affiliation(s)
- J M Edgar
- Applied Neurobiology Group, Institute of Comparative Medicine, University of Glasgow, Bearsden, Glasgow, Scotland.
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6
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Colby J, Nicholson R, Dickson KM, Orfali W, Naef R, Suter U, Snipes GJ. PMP22 carrying the trembler or trembler-J mutation is intracellularly retained in myelinating Schwann cells. Neurobiol Dis 2000; 7:561-73. [PMID: 11114256 DOI: 10.1006/nbdi.2000.0323] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Missense mutations in the murine peripheral myelin protein-22 gene (Pmp22) underly the neuropathies in the trembler (Tr) and trembler-J (Tr-J) mice and in some humans with Charcot-Marie-Tooth disease. We have generated replication-defective adenoviruses containing epitope-tagged, wild-type-, Tr-, or Tr-J-PMP22 bicistronic with the Lac-Z reporter gene. These viruses were microinjected into the sciatic nerves of 10-day-old Sprague-Dawley rats and, later, analyzed by immunohistochemistry to determine the distribution of mutant protein in infected myelinating Schwann cells. We found that epitope-tagged, wild-type PMP22 is successfully transported to compact myelin, whereas the Tr and the Tr-J mutant proteins are retained in cytoplasmic compartment, colocalizing with the endoplasmic reticulum. These results provide in vivo evidence that the pathogenesis of the Tr and Tr-J mutations are most likely a function of abnormal retention within the endoplasmic reticulum of myelinating Schwann cells.
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Affiliation(s)
- J Colby
- Department of Pathology, McGill University, Zürich, Switzerland
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7
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Ryan MC, Notterpek L, Tobler AR, Liu N, Shooter EM. Role of the peripheral myelin protein 22 N-linked glycan in oligomer stability. J Neurochem 2000; 75:1465-74. [PMID: 10987826 DOI: 10.1046/j.1471-4159.2000.0751465.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Peripheral myelin protein 22 (PMP22) is a 22-kDa glycoprotein containing a single N-linked carbohydrate moiety. This posttranslational modification is conserved in PMP22 across species and within members of the PMP22 gene family; however, the function of the oligosaccharide is not known. To study the role of the PMP22 carbohydrate, site-directed mutagenesis was used to alter the glycosylation consensus sequence and produce a glycosylation-deficient mutant protein. This modified PMP22 was expressed in primary Schwann cells (SCs), and the effect of the N-glycan on the turnover rate, oligomerization, and intracellular trafficking of PMP22 was determined. Our data show a slight decrease in turnover rate from a half-life of approximately 70 min for the wild-type (wt) protein to 100 min for the glycosylation mutant. Although the presence of glycosylation-deficient PMP22 oligomers could be detected in SCs, we observed a decrease in oligomer stability compared with the wt oligomers. Both wt and mutant proteins showed similar localization in the endoplasmic reticulum and Golgi compartments and were transported to the SC surface. These results suggest that the N-glycan of PMP22 facilitates, in part, the stability of the PMP22 oligomer; however, the implications of PMP22 oligomerization remain unknown.
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Affiliation(s)
- M C Ryan
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305-5125, USA
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8
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Uncoupling of myelin assembly and schwann cell differentiation by transgenic overexpression of peripheral myelin protein 22. J Neurosci 2000. [PMID: 10818147 DOI: 10.1523/jneurosci.20-11-04120.2000] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have generated previously transgenic rats that overexpress peripheral myelin protein 22 (PMP22) in Schwann cells. In the nerves of these animals, Schwann cells have segregated with axons to the normal 1:1 ratio but remain arrested at the promyelinating stage, apparently unable to elaborate myelin sheaths. We have examined gene expression of these dysmyelinating Schwann cells using semiquantitative reverse transcription-PCR and immunofluorescence analysis. Unexpectedly, Schwann cell differentiation appears to proceed normally at the molecular level when monitored by the expression of mRNAs encoding major structural proteins of myelin. Furthermore, an aberrant coexpression of early and late Schwann cell markers was observed. PMP22 itself acquires complex glycosylation, suggesting that trafficking of the myelin protein through the endoplasmic reticulum is not significantly impaired. We suggest that PMP22, when overexpressed, accumulates in a late Golgi-cell membrane compartment and uncouples myelin assembly from the underlying program of Schwann cell differentiation.
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Jetten AM, Suter U. The peripheral myelin protein 22 and epithelial membrane protein family. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2000; 64:97-129. [PMID: 10697408 DOI: 10.1016/s0079-6603(00)64003-5] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The peripheral myelin protein 22 (PMP22) and the epithelial membrane proteins (EMP-1, -2, and -3) comprise a subfamily of small hydrophobic membrane proteins. The putative four-transmembrane domain structure as well as the genomic structure are highly conserved among family members. PMP22 and EMPs are expressed in many tissues, and functions in cell growth, differentiation, and apoptosis have been reported. EMP-1 is highly up-regulated during squamous differentiation and in certain tumors, and a role in tumorigenesis has been proposed. PMP22 is most highly expressed in peripheral nerves, where it is localized in the compact portion of myelin. It plays a crucial role in normal physiological and pathological processes in the peripheral nervous system. Progress in molecular genetics has revealed that genetic alterations in the PMP22 gene, including duplications, deletions, and point mutations, are responsible for several forms of hereditary peripheral neuropathies, including Charcot-Marie-Tooth disease type 1A (CMT1A), Dejerine-Sottas syndrome (DDS), and hereditary neuropathy with liability to pressure palsies (HNPP). The natural mouse mutants Trembler and Trembler-J contain a missense mutation in different hydrophobic domains of PMP22, resulting in demyelination and Schwann cell proliferation. Transgenic mice carrying many copies of the PMP22 gene and PMP22-null mice display a variety of defects in the initial steps of myelination and/or maintenance of myelination, whereas no pathological alterations are detected in other tissues normally expressing PMP22. Further characterization of the interactions of PMP22 and EMPs with other proteins as well as their regulation will provide additional insight into their normal physiological function and their roles in disease and possibly will result in the development of therapeutic tools.
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Affiliation(s)
- A M Jetten
- Cell Biology Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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10
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Neuberg DH, Sancho S, Suter U. Altered molecular architecture of peripheral nerves in mice lacking the peripheral myelin protein 22 or connexin32. J Neurosci Res 1999; 58:612-23. [PMID: 10561689 DOI: 10.1002/(sici)1097-4547(19991201)58:5<612::aid-jnr2>3.0.co;2-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Peripheral nerves of mutant mice deficient for peripheral myelin protein 22 (PMP22) or connexin32 (Cx32) display similar pathologies as observed in hereditary human peripheral neuropathies. Mice lacking PMP22 develop focal hypermyelination followed by myelin degeneration and axonal atrophy. Cx32-deficient mice form normal myelin initially but develop demyelination and remyelination at older ages. We have examined the lack of PMP22 or Cx32 on the distribution of other components of the myelin sheath including myelin basic protein (MBP), E-cadherin, and myelin-associated glycoprotein (MAG), as well as the delayed rectifying potassium channel Kv1.1 as an intrinsic membrane protein of axons. In peripheral nerves of wild-type mice, Kv1.1 is present as a pair of juxtaparanodal clusters and a focal line extending longitudinally into the internode, branching parallel and adjacent to Schmidt-Lanterman incisures. Myelinated peripheral nerve fibers of 3-week-old PMP22(0/0) mice show tomacula and abnormally short internodes of variable lengths with minor effects on the localization of E-cadherin and Kv1.1. In older PMP22(0/0) mice, hypomyelinated fibers contain supernumerary Schwann cells and loose focally restricted E-cadherin and Kv1.1 expression. In contrast, remyelinated fibers in adult Cx32(0/0) mice exhibit a correct localization of these marker proteins, except that juxtaparanodal Kv1.1 clusters are aligned in abnormally short intervals of regular distances accompanied by an increased number of Schwann cells. Thus, different degrees of demyelination and remyelination in demyelinating mouse models have variable effects on the confinement of specific proteins to structural and functional internodal domains.
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Affiliation(s)
- D H Neuberg
- Institute of Cell Biology, Swiss Federal Institute of Technology, ETH Hönggerberg, Zürich, Switzerland
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11
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Wewetzer K, Archelos JJ, Hartung HP, Seilheimer B, Christ B. The monoclonal antibody 23E9 defines a novel developmentally-regulated Schwann cell surface antigen. Int J Dev Neurosci 1999; 17:715-25. [PMID: 10568688 DOI: 10.1016/s0736-5748(99)00046-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The present study describes the identification and partial characterization of a novel Schwann cell surface molecule by means of a monoclonal antibody (23E9). The 23E9 antigen was found in association with Schwann cells of the peripheral nerve but not with sensory neurons and satellite cells of the dorsal root ganglion. The expression of the antigen in the sciatic nerve starts after birth, is high around postnatal day 8 and becomes down-regulated towards the adult stage. This suggests that it may be involved in the induction of myelin formation. On Western blots, the antibody identified two major bands of approximately 27 and 42 kDa. Treatment of cultured Schwann cells with forskolin, an agent known to mimic neuronal contact in vitro, stimulated the up-regulation of the antigen. This implies that the expression of 23E9 is induced and maintained by axon-derived signals in vivo. Comparison of the presented data with the literature suggests that we have identified a novel cell surface molecule not previously characterized in the context of Schwann cell biology. To clarify the molecular identity of the antigen and define its physiological relevance, the antibody will be used in future studies for immunoprecipitation and functional in vitro assays.
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MESH Headings
- Aging/physiology
- Animals
- Animals, Newborn
- Antibodies, Monoclonal
- Antibody Specificity
- Antigens, Surface/analysis
- Antigens, Surface/genetics
- Antigens, Surface/immunology
- Cells, Cultured
- Enzyme-Linked Immunosorbent Assay
- Ganglia, Spinal/cytology
- Ganglia, Spinal/growth & development
- Ganglia, Spinal/metabolism
- Gene Expression Regulation, Developmental
- Rats
- Rats, Wistar
- Schwann Cells/cytology
- Schwann Cells/metabolism
- Sciatic Nerve/cytology
- Sciatic Nerve/growth & development
- Sciatic Nerve/metabolism
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Affiliation(s)
- K Wewetzer
- Hannover Medical School, Center of Anatomy, Germany.
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12
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Wulf P, Bernhardt RR, Suter U. Characterization of peripheral myelin protein 22 in zebrafish (zPMP22) suggests an early role in the development of the peripheral nervous system. J Neurosci Res 1999. [DOI: 10.1002/(sici)1097-4547(19990815)57:4%3c467::aid-jnr6%3e3.0.co;2-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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13
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Wulf P, Bernhardt RR, Suter U. Characterization of peripheral myelin protein 22 in zebrafish (zPMP22) suggests an early role in the development of the peripheral nervous system. J Neurosci Res 1999. [DOI: 10.1002/(sici)1097-4547(19990815)57:4<467::aid-jnr6>3.0.co;2-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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14
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Wulf P, Suter U. Embryonic expression of epithelial membrane protein 1 in early neurons. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1999; 116:169-80. [PMID: 10521561 DOI: 10.1016/s0165-3806(99)00092-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Epithelial membrane protein 1 (EMP1) is a member of the peripheral myelin protein 22 (PMP22) family. This family is best known for the crucial contribution of PMP22 to the development and maintenance of the peripheral nervous system (PNS). PMP22 is widely expressed, with highest levels in myelinating Schwann cells, and mutations affecting the PMP22 gene lead to PNS-restricted neuropathies. We have investigated the spatio-temporal distribution of EMP1 and compared it to that of PMP22. We found that EMP1 and PMP22 mRNA are most conspicuously expressed in the prenatal mouse brain during neurogenesis. In the developing forebrain, we localized EMP1 mRNA and protein to the first set of neurons that are generated and leave the ventricular zone to form the preplate. Later in development, EMP1 was found in derivatives of the preplate, the marginal zone and the subplate. Reduced expression was observed in the newly generated cortical plate neurons. In other parts of the developing CNS and PNS, EMP1 was also detected in early neurons and along the initial fiber tracts. Furthermore, EMP1 was highly expressed by immature neurons in embryonal dorsal root ganglia-explant cultures and in neuroectodermal differentiated P19 cells. While PMP22 functions mainly in Schwann cell growth and differentiation, the spatio-temporal localization of EMP1 suggests a role in neuronal differentiation and neurite outgrowth.
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Affiliation(s)
- P Wulf
- Institute of Cell Biology, Department of Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093, Zürich, Switzerland
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15
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Abstract
This selective review of Schwann cell biology focuses on questions relating to the origins, development and differentiation of Schwann cells and the signals that control these processes. The importance of neuregulins and their receptors in controlling Schwann cell precursor survival and generation of Schwann cells, and the role of these molecules in Schwann cell biology is addressed. The reciprocal signalling between peripheral glial cells and neurons in development and adult life revealed in recent years is highlighted, and the profound change in survival regulation from neuron-dependent Schwann cell precursors to adult Schwann cells that depend on autocrine survival signals is discussed. Besides providing neuronal and autocrine signals, Schwann cells signal to mesenchymal cells and influence the development of the connective tissue sheaths of peripheral nerves. The importance of Desert Hedgehog in this process is described. The control of gene expression during Schwann cell development and differentiation by transcription factors is reviewed. Knockout of Oct-6 and Krox-20 leads to delay or absence of myelination, and these results are related to morphological or physiological observations on knockout or mutation of myelin-related genes. Finally, the relationship between selected extracellular matrix components, integrins and the cytoskeleton is explored and related to disease.
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Affiliation(s)
- R Mirsky
- Department of Anatomy and Developmental Biology, University College London, UK.
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16
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17
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Naef R, Suter U. Impaired intracellular trafficking is a common disease mechanism of PMP22 point mutations in peripheral neuropathies. Neurobiol Dis 1999; 6:1-14. [PMID: 10078969 DOI: 10.1006/nbdi.1998.0227] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The most common forms of hereditary motor and sensory neuropathies (HMSN) or Charcot-Marie-Tooth disease (CMT) are associated with mutations affecting myelin genes in the peripheral nervous system. A minor subgroup of CMT type 1A (CMT1A) is caused by point mutations in the gene encoding the peripheral myelin protein 22 (PMP22). To study the mechanisms by which these mutations cause the CMT pathology, we transiently transfected COS7 and Schwann cells with wild-type and PMP22 expression constructs carrying six representative dominant or de novo point mutations and one putative recessive point mutation. All but one of the first group of mutant PMP22 proteins failed to be incorporated into the plasma membrane and were retained in intracellular compartments of transfected cells. Surprisingly, the recessive PMP22 mutation produced a protein that was also mildly impaired in trafficking. Thus, our results suggest a common disease mechanism underlying the pathology of CMT1A due to PMP22 point mutations.
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Affiliation(s)
- R Naef
- Institute of Cell Biology, Department of Biology, Swiss Federal Institute of Technology, ETH-Hoenggerberg, Zuerich
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18
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Neuberg DH, Suter U. Connexin32 in hereditary neuropathies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999; 468:227-36. [PMID: 10635032 DOI: 10.1007/978-1-4615-4685-6_18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- D H Neuberg
- Department of Biology, Swiss Federal Institute of Technology, ETH Hönggerberg, Zürich, Switzerland
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19
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Sindou P, Vallat JM, Chapon F, Archelos JJ, Tabaraud F, Anani T, Braund KG, Maisonobe T, Hauw JJ, Vandenberghe A. Ultrastructural protein zero expression in Charcot-Marie-Tooth type 1B disease. Muscle Nerve 1999; 22:99-104. [PMID: 9883862 DOI: 10.1002/(sici)1097-4598(199901)22:1<99::aid-mus14>3.0.co;2-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Charcot-Marie-Tooth type 1B (CMT 1B) disease, an inherited demyelinating peripheral neuropathy, results from different point mutations located in the P0 gene on chromosome 1 q21-23. We have quantified, at the ultrastructural level, the immunocytochemical expression of the P0 protein in two unrelated CMT 1B patients with mutations (Ser 78 to Leu and Asn 122 to Ser) located in two different exons in the extracellular domain of the protein. A twofold decrease in P0 expression was observed in compact myelin in each case, compared with age-matched controls. The severity of the phenotypes showed no direct relationship to the levels of P0 protein expression in these 2 patients.
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Affiliation(s)
- P Sindou
- Department of Neurology, University Hospital, Limoges, France
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20
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rMAL is a glycosphingolipid-associated protein of myelin and apical membranes of epithelial cells in kidney and stomach. J Neurosci 1998. [PMID: 9634556 DOI: 10.1523/jneurosci.18-13-04901.1998] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
rMAL, the rat myelin and lymphocyte protein, is a small hydrophobic protein of 17 kDa with four putative transmembrane domains and is expressed in oligodendrocytes and Schwann cells, the myelinating cells of the nervous system. In addition, transcript expression has been found in kidney, spleen, and intestine. Confocal microscopy and immunoelectron microscopy with an affinity-purified antibody localized rMAL to compact myelin in a pattern similar to the structural myelin proteins: myelin basic protein and proteolipid protein. In kidney and stomach epithelia, rMAL is located almost exclusively on the apical (luminal) membranes of the cells lining distal tubuli in kidney and the glandular part of the stomach. Biochemical analysis of plasma membranes isolated from spinal cord and kidney demonstrated that rMAL is a proteolipid that is present in detergent insoluble complexes typical for proteins associated with glycosphingolipids. Lipid and protein analysis showed a co-enrichment of glycosphingolipids and rMAL protein within these complexes, indicating a close association of rMAL to glycosphingolipids in myelin and in kidney in vivo. We conclude that specific rMAL-glycosphingolipid interactions may lead to the formation and maintenance of stable protein-lipid microdomains in myelin and apical epithelial membranes. They may contribute to specific properties of these highly specialized plasma membranes.
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21
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Abstract
Peripheral myelin protein 22 (PMP22) is a small, hydrophobic glycoprotein, which is most prominently expressed by Schwann cells as a component of compact myelin of the peripheral nervous system (PNS). Recent progress in molecular genetics revealed that mutations affecting the PMP22 gene including duplications, deletions, and point mutations are responsible for the most common forms of hereditary peripheral neuropathies including Charcot-Marie-Tooth disease type 1A (CMT1A), hereditary neuropathy with liability to pressure palsies (HNPP), and a subtype of Dejerine-Sottas Syndrome (DSS). Functionally, PMP22 is involved in correct myelination during development of peripheral nerves, the stability of myelin, and the maintenance of axons. While most of these functions relate to a role of PMP22 as a structural component of myelin, PMP22 has also been proposed as a regulator of Schwann cell proliferation and differentiation. In this review, we will discuss our current knowledge of PMP22 and its related proteins in the normal organism as well as in disease. In particular, we will focus on how the function of PMP22 and its regulation may be relevant to particular disease mechanisms.
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Affiliation(s)
- R Naef
- Department of Biology, Swiss Federal Institute of Technology, ETH-Hoenggerberg, Zurich
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22
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Abstract
Proteolipid protein (PLP) and its smaller isoform DM20 constitute the major myelin proteins of the CNS. Mutations of the X-linked Plp gene cause the heterogeneous syndromes of Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia (SPG) in man and similar dysmyelinating disorders in a range of animal species. A variety of mutations including missense mutations, deletions, and duplications are responsible. Missense mutations cause a predicted alteration in primary structure of the encoded protein(s) and are generally associated with early onset of signs and generalised dysmyelination. The severity of the phenotype varies according to the particular codon involved and the influence of uncharacterised modifying genes. There is some evidence that the dysmyelination results from the altered protein acquiring a novel function deleterious to the oligodendrocyte's function. Transgenic mice carrying extra copies of the Plp gene provide a valid model of PMD/SPG due to gene duplication. Depending on the gene dosage, the phenotype can vary from early onset of severe and lethal dysmyelination through to a very late onset of a tract-specific demyelination and axonal degeneration. Mice with a null mutation of the Plp gene assemble and maintain normal amounts of myelin but develop a progressive axonopathy, again demonstrating tract specificity. The results indicate that the functions of PLP are far from clear. There is good evidence that it is involved in the formation of the intraperiod line of myelin, and the results from the knockout and transgenic mice suggest a role in the interaction of oligodendrocyte and axon.
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Affiliation(s)
- I Griffiths
- Department of Veterinary Clinical Studies, University of Glasgow, Bearsden, Scotland.
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23
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Anderson TJ, Schneider A, Barrie JA, Klugmann M, McCulloch MC, Kirkham D, Kyriakides E, Nave KA, Griffiths IR. Late-onset neurodegeneration in mice with increased dosage of the proteolipid protein gene. J Comp Neurol 1998; 394:506-19. [PMID: 9590558 DOI: 10.1002/(sici)1096-9861(19980518)394:4<506::aid-cne8>3.0.co;2-5] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Mutations of the proteolipid protein (Plp) gene cause a generalized central nervous system (CNS) myelin deficit in Pelizaeus-Merzbacher disease of man and various tremor syndromes in animal models. X-linked spastic paraplegia is also due to Plp gene mutations but has a different clinical profile and more restricted pathology involving specific tracts and regions. We have shown previously that PLP overexpression in mice homozygous for a Plp transgene results in premature arrest of CNS myelination and premature death. Here, we demonstrate that a low-level increase in Plp gene expression in transgenic mice causes significant axonal degeneration and demyelination with predilection for specific tracts. Following normal motor development, aged mice develop progressive myelin loss, axonal swellings with resultant Wallerian degeneration, and marked vacuolation of the neuropil associated with ataxia, tremor, and seizures. The age of onset and severity of the phenotype is a function of Plp gene dosage. The corticospinal tracts, optic nerve, fasciculus gracilis cerebellum, and brainstem are particularly involved. Although oligodendrocyte cell bodies show little abnormality, their inner adaxonal tongue is often abnormal, suggesting a perturbation of the axon/glial interface that may underlie the axonal changes. We conclude that abnormal expression of an oligodendrocyte-specific gene can cause axonal damage, a finding that is relevant to the pathogenesis of PLP-associated disorders and probably to other myelin-related diseases.
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Affiliation(s)
- T J Anderson
- Applied Neurobiology Group, Department of Veterinary Clinical Studies, University of Glasgow, Scotland, United Kingdom
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24
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Schenone A, Nobbio L, Caponnetto C, Abbruzzese M, Mandich P, Bellone E, Ajmar F, Gherardi G, Windebank AJ, Mancardi G. Correlation between PMP-22 messenger RNA expression and phenotype in hereditary neuropathy with liability to pressure palsies. Ann Neurol 1997; 42:866-72. [PMID: 9403478 DOI: 10.1002/ana.410420607] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hereditary neuropathy with liability to pressure palsies (HNPP) is associated with a deletion in chromosome 17p11.2, which includes the gene for the peripheral myelin protein 22 (PMP-22). A "gene dosage" effect is probably the mechanism underlying HNPP, but the amount of PMP-22 mRNA in sural nerves of HNPP patients is highly variable and the role of PMP-22 underexpression in impairing myelination has yet to be clarified. We have studied 6 genetically proven HNPP patients, to evaluate the relationship between PMP-22 mRNA levels, and clinical, neurophysiological, and neuropathological findings. Underexpression of PMP-22 mRNA correlates with disease severity and with mean axon diameter and g ratio, but not with myelin thickness, number of "tomacula," or nerve conduction parameters. Our findings further confirm that underexpression of PMP-22 is the main pathogenetic mechanism underlying the severity of clinical symptoms and signs in HNPP. Smaller axons in sural nerves of HNPP patients with lower PMP-22 levels suggests that underexpression of PMP-22 may also affect axon development.
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Affiliation(s)
- A Schenone
- Department of Neurological Sciences and Rehabilitation, University of Genova, Italy
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25
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Suh JG, Ichihara N, Saigoh K, Nakabayashi O, Yamanishi T, Tanaka K, Wada K, Kikuchi T. An in-frame deletion in peripheral myelin protein-22 gene causes hypomyelination and cell death of the Schwann cells in the new Trembler mutant mice. Neuroscience 1997; 79:735-44. [PMID: 9219937 DOI: 10.1016/s0306-4522(96)00692-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cloning and sequencing of the peripheral myelin protein-22 cDNA and genomic DNA from newly found Trembler mice revealed an in-frame deletion including exon IV which codes for the second (TM2) and a part of third (TM3) transmembrane domain of peripheral myelin protein-22. This mutation was distinct from those in both other allelic Trembler and Trembler-J mice, which carry point mutations within the putative transmembrane spanning regions of peripheral myelin protein-22. Inheritance was autosomal dominant. The affected mice revealed an abnormal gait, which appeared at 15-20 days of age, followed by motor and sensory ataxia, which remained throughout life. Most of the affected mice could survive more than one year. One of the most notable pathological phenotypes was a giant vacuolar formation in the sciatic nerve of homozygotes. They vary in size within the cytoplasm of Schwann cells, which failed to assemble myelin at any ages studied. Heterozygotes showed normal myelination during the early postnatal stages, followed by a segmental demyelination at an advanced stage. Vacuolar formation was not so frequent as in the homozygotes. These results suggest that the missing of transmembrane spanning region (TM2 and TM3) of peripheral myelin protein-22 may disturb a dual biological function of peripheral myelin protein-22, leading to a dysmyelination of axons and to a vacuolar formation within the cytoplasm of the Schwann cells. The latter phenotype is discussed in conjunction with the disruption of an intracellular transport system and subsequent cell death.
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Affiliation(s)
- J G Suh
- Department of Animal Models for Human Disease, National Institute of Neuroscience, NCNP, Kodaira, Tokyo, Japan
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26
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Structural abnormalities and deficient maintenance of peripheral nerve myelin in mice lacking the gap junction protein connexin 32. J Neurosci 1997. [PMID: 9169515 DOI: 10.1523/jneurosci.17-12-04545.1997] [Citation(s) in RCA: 218] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mutations affecting the connexin 32 (Cx32) gene are associated with the X-linked form of the hereditary peripheral neuropathy Charcot-Marie-Tooth disease (CMTX). We show that Cx32-deficient mice develop a late-onset progressive peripheral neuropathy with abnormalities comparable to those associated with CMTX, thus providing proof of the critical role of Cx32 in the maintenance of peripheral nerve myelin and an animal model for CMTX. Frequently observed features include abnormally thin myelin sheaths, cellular onion bulb formation reflecting myelin degeneration-induced Schwann cell proliferation, and enlarged periaxonal collars while nerve conductance properties are altered only slightly. These observations are consistent with earlier hypotheses suggesting a function of Cx32 as a channel-forming protein that facilitates the communication between the abaxonal and adaxonal aspects of Schwann cell cytoplasm.
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27
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Abstract
A growing number of glycoproteins have been identified and characterized in myelin and myelin-forming cells. In addition to the major P0 glycoprotein of compact PNS myelin and the myelin-associated glycoprotein (MAG) in the periaxonal membranes of myelin-forming oligodendrocytes and Schwann cells, the list now includes peripheral myelin protein-22 (PMP-22), a 170 kDa glycoprotein associated with PNS myelin and Schwann cells (P170k/SAG), Schwann cell myelin protein (SMP), myelin/oligodendrocyte glycoprotein (MOG), and oligodendrocyte-myelin glycoprotein (OMgp). Many of these glycoproteins are members of the immunoglobulin superfamily and express the adhesion-related HNK-1 carbohydrate epitope. This review summarizes recent findings concerning the structure and function of these glycoproteins of myelin sheaths with emphasis on the physiological roles of oligosaccharide moieties.
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Affiliation(s)
- R H Quarles
- Myelin and Brain Development Section, NINDS, NIH, Bethesda, MD 20892, USA
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28
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Klugmann M, Schwab MH, Pühlhofer A, Schneider A, Zimmermann F, Griffiths IR, Nave KA. Assembly of CNS myelin in the absence of proteolipid protein. Neuron 1997; 18:59-70. [PMID: 9010205 DOI: 10.1016/s0896-6273(01)80046-5] [Citation(s) in RCA: 350] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Two proteolipid proteins, PLP and DM20, are the major membrane components of central nervous system (CNS) myelin. Mutations of the X-linked PLP/DM20 gene cause dysmyelination in mouse and man and result in significant mortality. Here we show that mutant mice that lack expression of a targeted PLP gene fail to exhibit the known dysmyelinated phenotype. Unable to encode PLP/DM20 or PLP-related polypeptides, oligodendrocytes are still competent to myelinate CNS axons of all calibers and to assemble compacted myelin sheaths. Ultrastructurally, however, the electron-dense 'intraperiod' lines in myelin remain condensed, correlating with its reduced physical stability. This suggests that after myelin compaction, PLP forms a stabilizing membrane junction, similar to a "zipper." Dysmyelination and oligodendrocyte death emerge as an epiphenomenon of other PLP mutations and have been uncoupled in the PLP null allele from the risk of premature myelin breakdown.
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Affiliation(s)
- M Klugmann
- Zentrum für Molekulare Biologie (ZMBH) University of Heidelburg, Federal Republic of Germany
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29
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Naef R, Adlkofer K, Lescher B, Suter U. Aberrant protein trafficking in Trembler suggests a disease mechanism for hereditary human peripheral neuropathies. Mol Cell Neurosci 1997; 9:13-25. [PMID: 9204477 DOI: 10.1006/mcne.1997.0604] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The naturally occurring mouse mutant Trembler (Tr) represents an animal model for inherited human neuropathies caused by point mutations affecting peripheral myelin protein 22 (PMP22). We describe the likely pathogenic cellular mechanism underlying the observed myelin deficiency. In Tr/+ animals, PMP22 immunoreactivity was found not only in compact myelin but also abundantly in the cytoplasm of Schwann cells. Based on these observations, the biosynthesis of wildtype and Tr protein was examined in transfected cells. While wildtype PMP22 was readily transported to the plasma membrane, Tr protein was localized mainly in the endoplasmic reticulum. Coexpression revealed a dominant effect of Tr on protein trafficking of wildtype PMP22. In agreement with the findings in vitro, Tr protein was not detectable in myelin of Tr/0 mice.
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Affiliation(s)
- R Naef
- Department of Biology, Swiss Federal Institute of Technology, Zurich, Switzerland
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30
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Taylor V, Suter U. Molecular Biology of Axon–Glia Interactions in the Peripheral Nervous System1. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0079-6603(08)61006-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
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31
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Affiliation(s)
- G J Snipes
- Department of Neuropathology, McGill University, Montreal, Quebec, Canada
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32
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Abstract
Spontaneous mutations that perturb myelination occur in a range of species including man, and together with engineered mutations have been used to study disease, normal myelination and axon/glial inter-relationships. Only a minority of the currently defined mutations have an apparently simple pathogenesis due to lack of a functional protein. Mutations in the myelin basic protein gene lead to a lack of protein, resulting in changes in the structure of myelin, which can be rescued by transgenic complementation. The pathogenesis of autosomal dominant and X-linked mutations affecting either oligodendrocytes or Schwann cells is more complex. Point mutations may act in a dominant negative manner and gene dosage is clearly linked to phenotypic change. Mutations in regulatory genes, such as those encoding transcription factors, can also disturb myelination by selected cell types. Other less-well studied and unexpected consequences of myelin mutations, such as seizures in mutations affecting genes expressed in Schwann cells and axonal changes associated with dysmyelination, are also considered. With the major developments in gene mapping and cloning it is now relevant to study mutations in a variety of species with the real prospect of defining their molecular basis. Examples are given of unusual, but potentially useful, uncharacterized mutations in dog and bovine.
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Affiliation(s)
- I R Griffiths
- Dept of Veterinary Clinical Studies, University of Glasgow, Bearsden, Scotland.
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33
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Murakami T, Garcia CA, Reiter LT, Lupski JR. Charcot-Marie-Tooth disease and related inherited neuropathies. Medicine (Baltimore) 1996; 75:233-50. [PMID: 8862346 DOI: 10.1097/00005792-199609000-00001] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Charcot-Marie-Tooth disease (CMT) was initially described more than 100 years ago by Charcot, Marie, and Tooth. It was only recently, however, that molecular genetic studies of CMT have uncovered the underlying causes of most forms of the diseases. Most cases of CMT1 are associated with a 1.5-Mb tandem duplication in 17p11.2-p12 that encompasses the PMP22 gene. Although many genes may exist in this large duplicated region, PMP22 appears to be the major dosage-sensitive gene. CMT1A is the first autosomal dominant disease associated with a gene dosage effect due to an inherited DNA rearrangement. There is no mutant gene, but instead the disease phenotype results from having 3 copies of a normal gene. Furthermore, these findings suggest that therapeutic intervention in CMT1A duplication patients may be possible by normalizing the amount of PMP22 mRNA levels. Alternatively, CMT1A can be caused by mutations in the PMP22 gene. Other forms of CMT are associated with mutations in the MPZ (CMT1B) and Cx32 (CMTX) genes. Thus, mutations in different genes can cause similar CMT phenotypes. The related but more severe neuropathy, Dejerine-Sottas syndrome (DSS), can also be caused by mutations in the PMP22 and MPZ genes. All 3 genes thus far identified by CMT researchers appear to play an important role in the myelin formation or maintenance of peripheral nerves. CMT1A, CMT1B, CMTX, hereditary neuropathy with liability to pressure palsies (HNPP), and DSS have been called myelin disorders or "myelino-pathies." Other demyelinating forms, CMT1C and CMT-AR, may be caused by mutations of not yet identified myelin genes expressed in Schwann cells. The clinically distinct disease HNPP is caused by a 1.5-Mb deletion in 17p11.2-p12, which spans the same region duplicated in most CMT1A patients. Underexpression of the PMP22 gene causes HNPP just as overexpression of PMP22 causes CMT1A. Thus, 2 different phenotypes can be caused by dosage variations of the same gene. It is apparent that the CMT1A duplication and HNPP deletion are the reciprocal products of a recombination event during meiosis mediated through the CMT1A-REPs. CMT1A and HNPP could be thought of as a "genomic disease" more than single gene disorders. Other genetic disorders may also prove to arise from recombination events mediated by specific chromosomal structural features of the human genome (102). Further studies on the recombination mechanism of CMT and HNPP might reveal the causes of site specific homologous recombination in the human genome. The discovery of the PMP22 gene in the 1.5-Mb CMT1A duplication/HNPP deletion critical region also suggests that the clinical phenotype of chromosome aneuploid syndromes may result from the effect of a small subset of dosage-sensitive genes mapping within the region of aneuploidy. The understanding of the molecular basis of CMT1 and related disorders has allowed accurate DNA diagnosis and genetic counseling of inherited peripheral neuropathies and will make it possible to develop rational strategies for therapy. As several loci for CMT2 have been identified, the genes responsible for CMT2 will most likely be disclosed using positional cloning and candidate gene approaches in the near future.
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Affiliation(s)
- T Murakami
- Departments of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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34
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Chimelli L. [Peripheral neuropathies in childhood: a neuropathological approach]. ARQUIVOS DE NEURO-PSIQUIATRIA 1996; 54:510-8. [PMID: 9110001 DOI: 10.1590/s0004-282x1996000300025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Peripheral neuropathies affect children more often than the young and middle age adults, but less frequently than the elderly. They differ from those in the adults because of the high incidence of hereditary neuropathies, including those associated with metabolic and degenerative disorders of the central nervous system; the low incidence of toxic neuropathies and those associated with systemic disorders; and a lower incidence of chronic acquire polineuropathies. Nerve biopsies are indicated if the diagnosis has not been made with clinical and electrophysiologic studies and other methods, and should only be performed in laboratories with appropriated techniques for the study of the nerve. It is important to know the normal development of the nerve, the thickness of the myelin sheath and the distribution of small and large fibers, according to the age. The main morphological aspects of the most frequent neuropathies in children--acquired (inflammatory, demyelinating) and hereditary (sensory-motor, sensory-autonomic, ataxic, and those associated with metabolic and degenerative disorders), are reviewed.
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Affiliation(s)
- L Chimelli
- Departamento de Patologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo (USP), Brasil
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35
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Guénard V, Montag D, Schachner M, Martini R. Onion bulb cells in mice deficient for myelin genes share molecular properties with immature, differentiated non-myelinating, and denervated Schwann cells. Glia 1996; 18:27-38. [PMID: 8891689 DOI: 10.1002/(sici)1098-1136(199609)18:1<27::aid-glia3>3.0.co;2-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Onion bulb formation is a pathological feature observed in peripheral nerves of patients suffering from inherited peripheral neuropathies such as Charcot-Marie-Tooth and Déjérine-Sottas diseases. An onion bulb consists of small circumferentially oriented (supernumerary) cells and their processes surrounding a large caliber axon. In the present study, we investigated the molecular phenotype of supernumerary cells at the light and electron microscopic levels. The major motor (quadriceps muscle) branch of the femoral nerve from 16- to 24-month-old mice with an inactivated allele of the myelin protein zero gene or deficient for myelin-associated glycoprotein (MAG; P0(+)- and MAG--mice, respectively), which have numerous onion bulbs, was teased to obtain single nerve fibers, which were then processed for immunocytochemistry. Corresponding nerves from wild-type mice served as controls. In both P0(+)- and MAG--mice, supernumerary cells expressed S-100, the low-affinity nerve growth factor receptor (p75, NGFr), the cell adhesion molecule L1, the neural cell adhesion molecule (N-CAM), and glial fibrillary acidic protein (GFAP). At the electron microscopic level, the cell surface of supernumerary cells was NGFr immunoreactive and L1 and N-CAM were expressed at points of contact between supernumerary cells. NGFr, L1, and N-CAM were also present in the basal lamina surrounding myelinated axons associated with onion bulbs. Both S-100 and GFAP immunoreactivities were seen in the cytoplasm of supernumerary cells. In contrast, in wild-type mice myelinating Schwann cells only expressed S-100 intracellularly and L1 and N-CAM in their basal lamina, whereas non-myelinating Schwann cells expressed all five molecules investigated. The present study indicates that supernumerary cells in onion bulbs have a molecular phenotype characteristic of immature, differentiated non-myelinating, and denervated Schwann cells, thus excluding the possibility that supernumerary cells are perineurial cells.
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Affiliation(s)
- V Guénard
- Department of Neurobiology, Swiss Federal Institute of Technology, Hönggerberg, Zürich, Switzerland
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36
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Zielasek J, Martini R, Toyka KV. Functional abnormalities in P0-deficient mice resemble human hereditary neuropathies linked to P0 gene mutations. Muscle Nerve 1996; 19:946-52. [PMID: 8756159 DOI: 10.1002/(sici)1097-4598(199608)19:8<946::aid-mus2>3.0.co;2-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Mutations in the gene encoding the transmembranous cell adhesion molecule, myelin protein zero (P0), have been reported in patients with Charcot-Marie-Tooth disease types 1B and 3 (Déjérine-Sottas disease). We have previously shown that the targeted deletion of the P0 gene in mice results in impairment of sciatic nerve conduction, and we now extend our detailed electrophysiologic investigation to the facial nerve. In concordance with histologic investigations which revealed severe hypomyelination in peripheral nerves we found the typical electrophysiologic signs of severe dysmyelination in both the facial and sciatic nerves in mice homozygously deficient for the expression of P0 (P0 -/- mice). As compared to control mice (P0+/+), nerve conduction velocities were reduced to below 10% and compound muscle action potential (CMAP) amplitudes to below 25%, while CMAP duration and excitation thresholds were markedly increased. Surprisingly, nerve conduction changes in mice heterozygously deficient for P0 (P0+/-) were only mild, were detected only in the sciatic nerve, and occurred not before 5-7 months of age. They were more prominent at age 12-13 months. Thus, P0 -/- mice resemble severe human inherited neuropathies like Charcot-Marie-Tooth disease type 3 (Déjérine-Sottas disease) with onset early in life, whereas the P0 +/- mice may resemble the milder form, CMT1B.
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Affiliation(s)
- J Zielasek
- Department of Neurology, Julius-Maximillians-University, Würzburg, Germany
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37
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Sereda M, Griffiths I, Pühlhofer A, Stewart H, Rossner MJ, Zimmerman F, Magyar JP, Schneider A, Hund E, Meinck HM, Suter U, Nave KA. A transgenic rat model of Charcot-Marie-Tooth disease. Neuron 1996; 16:1049-60. [PMID: 8630243 DOI: 10.1016/s0896-6273(00)80128-2] [Citation(s) in RCA: 272] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy in humans and has been associated with a partial duplication of chromosome 17 (CMT type 1A). We have generated a transgenic rat model of this disease and provide experimental evidence that CMT1A is caused by increased expression of the gene for peripheral myelin protein-22 (PMP22, gas-3). PMP22-transgenic rats develop gait abnormalities caused by a peripheral hypomyelination, Schwann cell hypertrophy (onion bulb formation), and muscle weakness. Reduced nerve conduction velocities closely resemble recordings in human patients with CMT1A. When bred to homozygosity, transgenic animals completely fail to elaborate myelin. We anticipate that the CMT rat model will facilitate the identification of a cellular disease mechanism and serve in the evaluation of potential treatment strategies.
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Affiliation(s)
- M Sereda
- Zentrum für Molekulare Biologie, University of Heidelberg, Federal Republic of Germany
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38
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Ouvrier R. Correlation between the histopathologic, genotypic, and phenotypic features of hereditary peripheral neuropathies in childhood. J Child Neurol 1996; 11:133-46. [PMID: 8881991 DOI: 10.1177/088307389601100214] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In recent years, there have been remarkable advances in the understanding of the molecular genetic basis of the hereditary polyneuropathies. Linkage of the genes for Charcot-Marie-Tooth disease to chromosomes 1 and then 17 was followed by the discovery that the commonest form of Charcot-Marie-Tooth disease (CMT1A) was due to a duplication of DNA at 17p11.2-12. This duplication was shown to contain the gene for peripheral myelin protein PMP22. The finding that mutations of the myelin protein PMP22 gene were present in some Charcot-Marie-Tooth disease cases lacking the duplication confirmed the myelin protein PMP22 gene as the site of the defect in Charcot-Marie-Tooth disease. Similarly, defects of the myelin protein P0 gene on chromosome 1 have been demonstrated in a rarer form of Charcot-Marie-Tooth disease (CMT1B). A deletion of DNA at 17p11.2-12 results in the disorder hereditary neuropathy with liability to pressure palsies. Other mutations of the myelin protein PMP22 and myelin protein P0 genes have been associated with the clinical syndrome known as Dejerine-Sottas disease. An X-linked form of Charcot-Marie-Tooth disease (CMTX) has been characterized and shown to be due to mutations of the gap junction protein, connexin 32. Transgenic murine models with inactivated myelin protein PMP22 and myelin protein P0 genes have shown pathologic changes strinkingly similar to those seen in human patients with disturbances of those genes. In this paper, the clinical and histopathologic characteristics of these conditions are discussed in relation to the genotypic basis. It will be argued that there is still an important place for the clinician and nerve pathologist in a medical world immersed in the wonders of molecular genetics.
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Affiliation(s)
- R Ouvrier
- Department of Neurology, University of Sydney, Australia
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39
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Karpati G, Lochmüller H, Nalbantoglu J, Durham H. The principles of gene therapy for the nervous system. Trends Neurosci 1996; 19:49-54. [PMID: 8820867 DOI: 10.1016/0166-2236(96)89620-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Research pertaining to gene transfer into cells of the nervous system is one of the fastest growing fields in neuroscience. An important application of gene transfer is gene therapy, which is based on introducing therapeutic genes into cells of the nervous system by ex vivo or in vivo techniques. With the eventual development of efficient and safe vectors, therapeutic genes, under the control of a suitable promoter, can be targeted to the appropriate neurons or glial cells. Gene therapy is not only applicable to the treatment of genetic diseases of the nervous system and the control of malignant neoplasia, but it also has therapeutic potential for acquired degenerative encephalopathies (Alzheimer's disease, Parkinson's disease), as well as for promoting neuronal survival and regeneration in various pathological states.
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Affiliation(s)
- G Karpati
- Montreal Neurological Institute, McGill University, Quebec, Canada
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