151
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Abstract
Charcot-Marie-Tooth (CMT) syndrome describes a genetically and clinically heterogeneous group of polyneuropathies. Electrophysiologically, at least two types of CMT can be distinguished; CMT1 which has decreased nerve conduction velocities (NCV) and CMT2 which has normal or near normal NCV with decreased amplitudes. For CMT1, three gene loci (on chromosomes 1, 17 and the X chromosome) have been mapped. The locus on chromosome 17, CMT type 1A (CMT1A), is responsible for the most common form of CMT which has recently been shown to be associated with a large DNA duplication. Recent data demonstrates that the CMT1A phenotype results from an inherited DNA rearrangement and a gene dosage effect. The trembler (Tr) and allelic tremblerJ (TrJ) mice have been proposed as animal models for CMT. Tr has similar electrophysiological and neuropathological features to CMT1 patients and maps to mouse chromosome 11 in a region of conserved synteny with human chromosome 17p. Tr and TrJ have recently been shown to have different point mutations in regions encoding putative transmembrane domains of the myelin specific protein PMP-22. The human peripheral nerve-specific PMP-22 gene maps within the CMT1A duplication. PMP-22 is thus a candidate gene for CMT1A. This paper describes the molecular genetics of CMT1A and sural nerve pathology in CMT1A patients with the CMT1A duplication.
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Affiliation(s)
- J R Lupski
- Institute for Molecular Genetics, Baylor College of Medicine, Houston, TX 77030
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152
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Regulation and expression of a growth arrest-specific gene (gas5) during growth, differentiation, and development. Mol Cell Biol 1992. [PMID: 1630459 DOI: 10.1128/mcb.12.8.3514] [Citation(s) in RCA: 139] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The growth arrest-specific gas5 gene was isolated from mouse genomic DNA and structurally characterized. The transcriptional unit is divided into 12 exons that span around 7 kb. An alternative splicing mechanism gives rise to two mature mRNAs which contain either 11 or 12 exons, and both are found in the cytoplasm of growth-arrested cells. In vivo, the gas5 gene is ubiquitously expressed in mouse tissues during development and adult life. In Friend leukemia and NIH 3T3 cells, the levels of gas5 gene mRNA were high in saturation density-arrested cells and almost undetectable in actively growing cells. Run-on experiments indicated that the gas5 gene is transcribed at the same level in both growing and arrested cells. On the other hand, in dimethyl sulfoxide-induced differentiating cells a sharp decrease in the rate of transcription was observed shortly before the cells reached the postmitotic stage. These results indicate that in density-arrested cells accumulation of gas5 mRNA is controlled at the posttranscriptional level while in differentiating cells expression is regulated transcriptionally.
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153
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Coccia EM, Cicala C, Charlesworth A, Ciccarelli C, Rossi GB, Philipson L, Sorrentino V. Regulation and expression of a growth arrest-specific gene (gas5) during growth, differentiation, and development. Mol Cell Biol 1992; 12:3514-21. [PMID: 1630459 PMCID: PMC364604 DOI: 10.1128/mcb.12.8.3514-3521.1992] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The growth arrest-specific gas5 gene was isolated from mouse genomic DNA and structurally characterized. The transcriptional unit is divided into 12 exons that span around 7 kb. An alternative splicing mechanism gives rise to two mature mRNAs which contain either 11 or 12 exons, and both are found in the cytoplasm of growth-arrested cells. In vivo, the gas5 gene is ubiquitously expressed in mouse tissues during development and adult life. In Friend leukemia and NIH 3T3 cells, the levels of gas5 gene mRNA were high in saturation density-arrested cells and almost undetectable in actively growing cells. Run-on experiments indicated that the gas5 gene is transcribed at the same level in both growing and arrested cells. On the other hand, in dimethyl sulfoxide-induced differentiating cells a sharp decrease in the rate of transcription was observed shortly before the cells reached the postmitotic stage. These results indicate that in density-arrested cells accumulation of gas5 mRNA is controlled at the posttranscriptional level while in differentiating cells expression is regulated transcriptionally.
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Affiliation(s)
- E M Coccia
- European Molecular Biology Laboratory, Heidelberg, Germany
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154
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Brancolini C, Bottega S, Schneider C. Gas2, a growth arrest-specific protein, is a component of the microfilament network system. J Cell Biol 1992; 117:1251-61. [PMID: 1607387 PMCID: PMC2289493 DOI: 10.1083/jcb.117.6.1251] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In this report we analyze the protein product of a growth arrest-specific gene, gas2, by means of an affinity-purified antibody raised against the protein produced in bacteria. The regulation of Gas2 biosynthesis reflects the pattern of mRNA expression (Schneider, C., R. King, and L. Philipson. 1988. Cell. 54:787-793): its relative level is tightly associated with growth arrest. Gas2 seems to be regulated also at the posttranslational level via a phosphorylation mechanism. Gas2 is well conserved during the evolution with the same apparent molecular mass (36 kD) between mouse and human. We also demonstrate that Gas2 is a component of the microfilament system. It colocalizes with actin fiber, at the cell border and also along the stress fiber, in growth-arrested NIH 3T3 cells. The pattern of distribution, detected in arrested cells, can also be observed in growing cells when they are microinjected with the purified GST-Gas2 protein. In none of the analyzed oncogene-transformed NIH 3T3 cell lines was Gas2 expression induced under serum starvation.
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Affiliation(s)
- C Brancolini
- International Center for Genetic Engineering and Biotechnology (I.C.G.E.B.) Trieste, Italy
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155
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Patel PI, Roa BB, Welcher AA, Schoener-Scott R, Trask BJ, Pentao L, Snipes GJ, Garcia CA, Francke U, Shooter EM, Lupski JR, Suter U. The gene for the peripheral myelin protein PMP-22 is a candidate for Charcot-Marie-Tooth disease type 1A. Nat Genet 1992; 1:159-65. [PMID: 1303228 DOI: 10.1038/ng0692-159] [Citation(s) in RCA: 351] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Charcot-Marie-Tooth disease type 1A (CMT1A) is an autosomal dominant peripheral neuropathy associated with a large DNA duplication on the short arm of human chromosome 17. The trembler (Tr) mouse serves as a model for CMT1A because of phenotypic similarities and because the Tr locus maps to mouse chromosome 11 in a region of conserved synteny with human chromosome 17. Recently, the peripheral myelin gene Pmp-22 was found to carry a point mutation in Tr mice. We have isolated cDNA and genomic clones for human PMP-22. The gene maps to human chromosome 17p11.2-17p12, is expressed at high levels in peripheral nervous tissue and is duplicated, but not disrupted, in CMT1A patients. Thus, we suggest that a gene dosage effect involving PMP-22 is at least partially responsible for the demyelinating neuropathy seen in CMT1A.
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Affiliation(s)
- P I Patel
- Institute for Molecular Genetics, Baylor College of Medicine, Houston, Texas 77030
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156
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Matsunami N, Smith B, Ballard L, Lensch MW, Robertson M, Albertsen H, Hanemann CO, Müller HW, Bird TD, White R. Peripheral myelin protein-22 gene maps in the duplication in chromosome 17p11.2 associated with Charcot-Marie-Tooth 1A. Nat Genet 1992; 1:176-9. [PMID: 1303231 DOI: 10.1038/ng0692-176] [Citation(s) in RCA: 210] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Charcot-Marie-Tooth disease 1A (CMT1A) is a hereditary demyelinating peripheral neuropathy, associated with a DNA duplication on chromosome 17p11.2. A related disorder in the mouse, trembler (Tr), maps to mouse chromosome 11 which has syntenic homology to human chromosome 17p. Recently, the peripheral myelin protein-22 (pmp-22) gene was identified as the likely Tr locus. We have constructed a partial yeast artificial chromosome contig spanning the CMT1A gene region and mapped the PMP-22 gene to the duplicated region. These observations further implicate PMP-22 as a candidate gene for CMT1A, and suggest that over-expression of this gene may be one mechanism that produces the CMT1A phenotype.
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Affiliation(s)
- N Matsunami
- Howard Hughes Medical Institute, University of Utah Medical Center, Salt Lake City 84112
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157
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Timmerman V, Nelis E, Van Hul W, Nieuwenhuijsen BW, Chen KL, Wang S, Ben Othman K, Cullen B, Leach RJ, Hanemann CO. The peripheral myelin protein gene PMP-22 is contained within the Charcot-Marie-Tooth disease type 1A duplication. Nat Genet 1992; 1:171-5. [PMID: 1303230 DOI: 10.1038/ng0692-171] [Citation(s) in RCA: 263] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Charcot-Marie-Tooth disease (CMT1) is the most common form of inherited peripheral neuropathy. Although the disease is genetically heterogeneous, it has been demonstrated that the gene defect is the most frequent type (CMT1A) is the result of a partial duplication of band 17p11.2. Recent studies suggested that the peripheral hypomyelination syndrome in the trembler (Tr) mouse, a possible animal model for CMT1 disease, is associated with a point mutation in the peripheral myelin protein-22 gene (pmp-22). Expression of pmp-22 is particularly high in Schwann cells, and the protein is found in peripheral myelin. We now report that the human PMP-22 gene is contained within the CMT1A duplication. We therefore, suggest that increased dosage of the PMP-22 gene may be the cause of CMT1A neuropathy.
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Affiliation(s)
- V Timmerman
- Laboratory of Neurogenetics, Born Bunge Foundation, University of Antwerp, Belgium
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158
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Valentijn LJ, Bolhuis PA, Zorn I, Hoogendijk JE, van den Bosch N, Hensels GW, Stanton VP, Housman DE, Fischbeck KH, Ross DA. The peripheral myelin gene PMP-22/GAS-3 is duplicated in Charcot-Marie-Tooth disease type 1A. Nat Genet 1992; 1:166-70. [PMID: 1303229 DOI: 10.1038/ng0692-166] [Citation(s) in RCA: 224] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Charcot-Marie-Tooth disease type 1A (CMT1A) is associated with a DNA duplication at chromosome 17p11.2. In view of the point mutation in the gene for peripheral myelin protein pmp-22/gas-3 in Trembler mice, a murine model for CMT1A, we have analysed whether this gene is altered in CMT1A. Here we show that the human homologue of the murine pmp-22 gene is located within the CMT1A DNA duplication, which is a direct repeat and does not interrupt the coding region of PMP-22. Expression of PMP-22 in CMT1A fibroblasts is similar to expression in control fibroblasts. Increased gene dosage or altered PMP-22 expression in the peripheral nervous system are therefore possible mechanisms by which PMP-22 is involved in CMT1A.
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Affiliation(s)
- L J Valentijn
- Department of Neurology, Academical Medical Center, Amsterdam, The Netherlands
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159
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Suter U, Moskow JJ, Welcher AA, Snipes GJ, Kosaras B, Sidman RL, Buchberg AM, Shooter EM. A leucine-to-proline mutation in the putative first transmembrane domain of the 22-kDa peripheral myelin protein in the trembler-J mouse. Proc Natl Acad Sci U S A 1992; 89:4382-6. [PMID: 1374899 PMCID: PMC49086 DOI: 10.1073/pnas.89.10.4382] [Citation(s) in RCA: 217] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Peripheral myelin protein PMP-22 is a potential growth-regulating myelin protein that is expressed by Schwann cells and predominantly localized in compact peripheral myelin. A point mutation in the Pmp-22 gene of inbred trembler (Tr) mice was identified and proposed to be responsible for the Tr phenotype, which is characterized by paralysis of the limbs as well as tremors and transient seizures. In support of this hypothesis, we now report the fine mapping of the Pmp-22 gene to the immediate vicinity of the Tr locus on mouse chromosome 11. Furthermore, we have found a second point mutation in the Pmp-22 gene of trembler-J (TrJ) mice, which results in the substitution of a leucine residue by a proline residue in the putative first transmembrane region of the PMP-22 polypeptide. Tr and TrJ were previously mapped genetically as possible allelic mutations giving rise to similar, but not identical, phenotypes. This finding is consistent with the discovery of two different mutations in physicochemically similar domains of the PMP-22 protein. Our results strengthen the hypothesis that mutations in the Pmp-22 gene can lead to heterogeneous forms of peripheral neuropathies and offer clues toward possible explanations for the dominant inheritance of these disorders.
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Affiliation(s)
- U Suter
- Department of Neurobiology, Stanford University School of Medicine, CA 94305-5401
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160
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Snipes GJ, Suter U, Welcher AA, Shooter EM. Characterization of a novel peripheral nervous system myelin protein (PMP-22/SR13). J Biophys Biochem Cytol 1992; 117:225-38. [PMID: 1556154 PMCID: PMC2289391 DOI: 10.1083/jcb.117.1.225] [Citation(s) in RCA: 304] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We have recently described a novel cDNA, SR13 (Welcher, A. A., U. Suter, M. De Leon, G. J. Snipes, and E. M. Shooter. 1991. Proc. Natl. Acad. Sci. USA. 88:7195-7199), that is repressed after sciatic nerve crush injury and shows homology to both the growth arrest-specific mRNA, gas3 (Manfioletti, G., M. E. Ruaro, G. Del Sal, L. Philipson, and C. Schneider, 1990. Mol. Cell Biol. 10:2924-2930), and to the myelin protein, PASII (Kitamura, K., M. Suzuki, and K. Uyemura. 1976. Biochim. Biophys. Acta. 455:806-816). In this report, we show that the 22-kD SR13 protein is expressed in the compact portion of essentially all myelinated fibers in the peripheral nervous system. Although SR13 mRNA was found in the central nervous system, no corresponding SR13 protein could be detected by either immunoblot analysis or by immunohistochemistry. Northern and immunoblot analysis of SR13 mRNA and protein expression during development of the peripheral nervous system reveal a pattern similar to other myelin proteins. Furthermore, we demonstrate by in situ mRNA hybridization on tissue sections and on individual nerve fibers that SR13 mRNA is produced predominantly by Schwann cells. We conclude that the SR13 protein is apparently exclusively expressed in the peripheral nervous system where it is a major component of myelin. Thus, we propose the name Peripheral Myelin Protein-22 (PMP-22) for the proteins and cDNA previously designated PASII, SR13, and gas3.
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Affiliation(s)
- G J Snipes
- Department of Neurobiology, Stanford University School of Medicine, CA 94305
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161
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Suter U, Welcher AA, Ozcelik T, Snipes GJ, Kosaras B, Francke U, Billings-Gagliardi S, Sidman RL, Shooter EM. Trembler mouse carries a point mutation in a myelin gene. Nature 1992; 356:241-4. [PMID: 1552943 DOI: 10.1038/356241a0] [Citation(s) in RCA: 340] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The autosomal dominant trembler mutation (Tr), maps to mouse chromosome 11 (ref. 2) and manifests as a Schwann-cell defect characterized by severe hypomyelination and continuing Schwann-cell proliferation throughout life. Affected animals move clumsily and develop tremor and transient seizures at a young age. We have recently described a potentially growth-regulating myelin protein, peripheral myelin protein-22 (PMP-22; refs 7, 8), which is expressed by Schwann cells and found in peripheral myelin. We now report the assignment of the gene for PMP-22 to mouse chromosome 11. Cloning and sequencing of PMP-22 complementary DNAs from inbred Tr mice reveals a point mutation that substitutes an aspartic acid residue for a glycine in a putative membrane-associated domain of the PMP-22 protein. Our results identify the PMP-22 gene as a likely candidate for the mouse trembler locus and will encourage the search for mutations in the corresponding human gene in pedigrees with hypertrophic neuropathies such as Charcot-Marie-Tooth and Dejerine-Sottas diseases (hereditary motor and sensory neuropathies I and III).
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Affiliation(s)
- U Suter
- Department of Neurobiology, Stanford University School of Medicine, California 94305
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162
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Welcher AA, De Leon M, Suter U, Snipes GJ, Meakin SO, Shooter EM. Isolation of transcriptionally regulated sequences associated with neuronal and non-neuronal cell interactions. PROGRESS IN BRAIN RESEARCH 1992; 94:163-76. [PMID: 1287719 DOI: 10.1016/s0079-6123(08)61748-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- A A Welcher
- Department of Neurobiology, Stanford University, CA 94305
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