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Lefebvre S, Wzietek P, Brown S, Bourbonnais C, Jérome D, Mézière C, Fourmigué M, Batail P. Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors. PHYSICAL REVIEW LETTERS 2000; 85:5420-5423. [PMID: 11136011 DOI: 10.1103/physrevlett.85.5420] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2000] [Indexed: 05/23/2023]
Abstract
The phase diagram of the organic superconductor kappa-(ET)2Cu[N(CN)2]Cl has been accurately measured from 1H NMR and ac susceptibility techniques under helium gas pressure. The domains of stability of antiferromagnetic and superconducting orders in the pressure vs temperature plane have been determined. Both phases overlap through a first-order boundary that separates two regions of inhomogeneous phase coexistence. The boundary curve merges with the first-order line of the metal-insulator transition which ends with a critical point at higher temperature. The whole phase diagram features a point-like region where metallic, insulating, antiferromagnetic, and non-s-wave superconducting phases all meet.
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52
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Lefebvre S, Quivy A, Bigot J, Calvayrac Y, Bellissent R. A neutron diffraction determination of short-range order in a Ni63.7Zr36.3glass. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0305-4608/15/5/001] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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53
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Lefebvre S, Adrian F, Moreau P, Gourand L, Dausset J, Berrih-Aknin S, Carosella ED, Paul P. Modulation of HLA-G expression in human thymic and amniotic epithelial cells. Hum Immunol 2000; 61:1095-101. [PMID: 11137212 DOI: 10.1016/s0198-8859(00)00192-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Expression of the nonclassical HLA class I antigen, HLA-G, is tightly regulated. HLA-G physiologic expression is mostly restricted to some placental and thymic cell types. Only few established cell lines express HLA-G in vitro. Cytokine-induced expression of HLA-G is hardly observed and also depends on the cell lineage. We assessed expression and cytokine regulation of HLA-G in primary cultures derived from human thymus and amnion epithelial cells, which also express HLA-G in vivo. We show that HLA-G cell surface expression is maintained, but decreases gradually, in primary cultures derived from human thymus and amnion epithelial cells. We also show that IFN-gamma re-induces HLA-G cell surface expression and upregulates classical class I gene expression in both primary cultures and in a thymus derived cell line. We further show that IFN-gamma also upregulates levels of HLA-G transcripts in TEC primary cultures. This study provides evidence that IFN-gamma induction of HLA-G expression occurs in the human amnion and the thymus, and is mediated at the transcriptional level in these tissues. These results also suggest a role for the microenvironment in regulating HLA-G in vivo gene expression in the thymus and amnion membrane.
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54
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Paul P, Cabestre FA, Ibrahim EC, Lefebvre S, Khalil-Daher I, Vazeux G, Quiles RM, Bermond F, Dausset J, Carosella ED. Identification of HLA-G7 as a new splice variant of the HLA-G mRNA and expression of soluble HLA-G5, -G6, and -G7 transcripts in human transfected cells. Hum Immunol 2000; 61:1138-49. [PMID: 11137219 DOI: 10.1016/s0198-8859(00)00197-x] [Citation(s) in RCA: 238] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The nonclassical HLA-G primary transcript is alternatively spliced to generate several mRNAs that have the capacity to encode four membrane bound isoforms, namely HLA-G1, -G2, -G3, and -G4 and two soluble isoforms HLA-G5 and -G6. We aimed at defining the capacity of full length and truncated soluble HLA-G transcripts to be translated in human cell lines. Our study of HLA-G alternative transcripts in various human tissues led us to identify a new splice variant of the HLA-G mRNA, named G7, in which open reading frame continues in intron 2. Due to the presence of a stop codon within intron 2, HLA-G7 transcripts retain the capacity to be translated as soluble truncated HLA-G proteins bearing the alpha1 domain linked to two specific aminoacids encoded by intron 2. Expression vectors containing cDNAs encoding HLA-G5, -G6, and -G7 isoforms were transfected into human cell lines. The presence of translated HLA-G5, -G6, and -G7 proteins was detected in protein extracts of transfected cells by Western blot and immunoprecipitation, but only the full length HLA-G5 soluble isoform could be clearly detected as a secreted protein in both transfected cells supernatants and body fluids.
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55
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LaPlante SR, Aubry N, Bonneau PR, Kukolj G, Lamarre D, Lefebvre S, Li H, Llinàs-Brunet M, Plouffe C, Cameron DR. NMR line-broadening and transferred NOESY as a medicinal chemistry tool for studying inhibitors of the hepatitis C virus NS3 protease domain. Bioorg Med Chem Lett 2000; 10:2271-4. [PMID: 11055336 DOI: 10.1016/s0960-894x(00)00466-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This work describes the use of NMR as a medicinal chemistry tool for better understanding the binding characteristics of inhibitors of the HCV NS3 protease. The protease-bound structure of a tetrapeptide-like inhibitor that has an acid C-terminus, a norvaline at P1 and a naphthylmethoxy proline at P2 is described. Conformational comparisons are made with a similar compound having a 1-amino-cyclopropylcarboxylic acid at P1 and with a hexapeptide inhibitor. Differences between the free and bound states are identified. 19F NMR also helped in determining that a single complex is observed when an inhibitor is added to the protease at a 1:1 ratio.
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56
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Pallarès N, Lefebvre S, Contet V, Matsuda F, Lefranc MP. The human immunoglobulin heavy variable genes. EXPERIMENTAL AND CLINICAL IMMUNOGENETICS 2000; 16:36-60. [PMID: 10087405 DOI: 10.1159/000019095] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
'Human Immunoglobulin Heavy Variable Genes', the fourth report of the 'IMGT Locus on Focus' section, comprises five tables entitled: (1) 'Number of human germline IGHV genes at 14q32.33 and potential repertoire'; (2) 'Human germline IGHV genes at 14q32.33'; (3) 'Human IGHV orphons on chromosome 15 (15q11.2)'; (4) 'Human IGHV orphons on chromosome 16 (16p11.2)', and (5) 'Human IGHV allele table'. These tables are available at the IMGT Marie-Paule page from IMGT, the international ImMunoGeneTics database (http://imgt.cnusc.fr:8104) created by Marie-Paule Lefranc, Université Montpellier II, CNRS, France.
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57
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Vartanian T, Goodearl A, Lefebvre S, Park SK, Fischbach G. Neuregulin induces the rapid association of focal adhesion kinase with the erbB2-erbB3 receptor complex in schwann cells. Biochem Biophys Res Commun 2000; 271:414-7. [PMID: 10799311 DOI: 10.1006/bbrc.2000.2624] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neuregulins signal cells by binding to an activating hetero- and homodimeric forms of the neuregulin receptors HER2 (erbB2), HER3 (erbB3), and HER4 (erbB4). Axonally derived neuregulin signals myelin forming cells of the central and peripheral nervous systems through different receptor complexes: oligodendrocytes through erbB2/erbB4 heterodimers and Schwann cells through erbB2/erbB3 heterodimers. Since the leading edge of myelinating cells interacts directly with the axonal surface, we were interested in determining if signaling molecules localized at the leading edge associate with activated neuregulin receptors. We found a novel association between neuregulin receptors and focal adhesion kinase (FAK) in primary cultures of Schwann cells. Following stimulation with ligand, maximal binding of FAK to HER2 occurred by 1 min whereas maximal binding to HER3 was delayed to approximately 7 min. FAK is localized in focal adhesions of Schwann cells. We have previously shown HER2 and HER3 are distributed evenly throughout the plasmalemma. Neuregulins thus use FAK to transmit intracellular signals and the differential kinetics of FAK association with individual neuregulin receptors, as well as its restricted subcellular localization, may play a role in specifying biologic responses.
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58
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Frebourg NB, Lefebvre S, Baert S, Lemeland JF. PCR-Based assay for discrimination between invasive and contaminating Staphylococcus epidermidis strains. J Clin Microbiol 2000; 38:877-80. [PMID: 10655405 PMCID: PMC86232 DOI: 10.1128/jcm.38.2.877-880.2000] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The discrimination between Staphylococcus epidermidis strains that contaminate and infect blood cultures is a daily challenge for clinical laboratories. The results of PCR detection of putative virulence genes were compared for contaminating strains, sepsis-related strains, catheter strains, and saprophytic strains. Multiplex PCR was used to explore the atlE gene, which is involved in initial adherence, the intercellular adhesion gene cluster (ica), which mediates the formation of the biofilm, and the agrA, sarA, and mecA genes, which might contribute to the pathogenicity of S. epidermidis. Whereas the atlE, agrA, and sarA genes were almost ubiquitously amplified, the ica and mecA genes were detected significantly more in infecting strains than in contaminating strains (P </= 0.02) and thus appeared to be related to the potential virulence of S. epidermidis.
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59
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Capitan MJ, Lefebvre S, Calvayrac Y, Bessiere M, Cenedese P. Study of the chemical dependence of the effective pair potentials of Co–Pt alloy. J Appl Crystallogr 1999. [DOI: 10.1107/s002188989900998x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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60
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Capitan MJ, Lefebvre S, Calvayrac Y, Bessiere M, Cenedese P. Study of the chemical dependence of the effective pair potentials of Co–Pt alloy. J Appl Crystallogr 1999. [DOI: 10.1107/s0021889899009887] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Effective pair interaction potentials of Co–Pt alloy have been obtained from X-ray diffuse scattering measurements on short-range ordered Co3Pt and Co65Pt35single crystals. The present work presents the evolution of the interaction energies in the Co–Pt alloy when the Pt concentration varies from 25 to 35 at. %. The aim of this work was to provide data in order to improve the computation of the phase diagram by allowing a concentration dependence of the effective pair potentials. Different methods have been proposed for separating the contributions of local order and first-order displacements from the total diffuse intensity. A comparison of different methods of analysis of Co3Pt diffuse-scattering intensity data is reported in the Appendix of this article; it shows that the second-order displacement terms are almost zero near the transition temperature.
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61
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Lefebvre S, Moreau P, Guiard V, Ibrahim EC, Adrian-Cabestre F, Menier C, Dausset J, Carosella ED, Paul P. Molecular mechanisms controlling constitutive and IFN-gamma-inducible HLA-G expression in various cell types. J Reprod Immunol 1999; 43:213-24. [PMID: 10479057 DOI: 10.1016/s0165-0378(99)00035-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
HLA-G molecule is thought to play a major role in down-regulating the maternal immune response by inhibiting NK and T cell cytolytic activities. We examined the molecular regulatory mechanisms that may control the restricted expression pattern of the HLA-G gene. We first analyzed protein interactions between nuclear extracts from the HLA-G-positive JEG-3 choriocarcinoma and the HLA-G-negative NK-like YT2C2 cell lines to a 244 bp regulatory element located 1.2 kb from the HLA-G gene, previously shown to direct HLA-G expression in transgenic mouse placenta. This allowed characterization of cell-specific DNA-protein interactions that could account for differential cell-specific expression of the HLA-G gene. In particular two DNA-protein complexes were exclusively observed in YT2C2, suggesting that this HLA-G regulatory element is a target for putative cell-specific repressor factors. We further mapped nuclear factor binding sites to a 70 bp fragment in the upstream region of the regulatory element. We then investigated the effect of IFN-gamma on HLA-G gene expression. HLA-G cell surface expression was enhanced by IFN-gamma treatment in JEG-3 and U937 cell lines and peripheral blood monocytes while no effect was observed in tera-2 teratocarcinoma cell line. HLA-G transcriptional activity was increased only in JEG-3 and U937 cell lines. Activity of the 1.4-kb HLA-G promoter region was unchanged after IFN-gamma treatment in JEG-3 and Tera-2. These results suggest that both post-transcriptional and transcriptional mechanisms implicating IFN-responsive regulatory sequences outside the 1.4 kb-region are involved in IFN-gamma gene activation of the HLA-G gene.
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62
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LaPlante SR, Cameron DR, Aubry N, Lefebvre S, Kukolj G, Maurice R, Thibeault D, Lamarre D, Llinàs-Brunet M. Solution structure of substrate-based ligands when bound to hepatitis C virus NS3 protease domain. J Biol Chem 1999; 274:18618-24. [PMID: 10373473 DOI: 10.1074/jbc.274.26.18618] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The interactions of the NS3 protease domain with inhibitors that are based on N-terminal cleavage products of peptide substrates were studied by NMR methods. Transferred nuclear Overhauser effect experiments showed that these inhibitors bind the protease in a well defined, extended conformation. Protease-induced line-broadening studies helped identify the segments of inhibitors which come into contact with the protease. A comparison of the NMR data of the free and protease-bound states suggests that these ligands undergo rigidification upon complexation. This work provides the first structure of an inhibitor when bound to NS3 protease and should be valuable for designing more potent inhibitors.
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63
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Lefebvre S, Moreau P, Dausset J, Carosella ED, Paul P. Downregulation of HLA class I gene transcription in choriocarcinoma cells is controlled by the proximal promoter element and can be reversed by CIITA. Placenta 1999; 20:293-301. [PMID: 10329350 DOI: 10.1053/plac.1998.0380] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The expression pattern of MHC class I genes in trophoblast cells at the feto-maternal interface is thought to be the basis of the maintenance of pregnancy by protecting the fetus from maternal immune rejection. Transcription of classical HLA class I genes is low or undetectable in most trophoblast cells as well as in JEG-3 and BeWo trophoblast-derived choriocarcinoma cells. The aim of this study was to characterize the regulatory mechanisms that repress HLA-A transcription in these cell types. We show that the -335 to ATG region of the HLA-A11 gene promoter is inactive in JEG-3 and BeWo cells while able to control efficient reporter gene transcription in other cell types, indicating that this region is the target for downregulation of HLA-A expression in choriocarcinoma cell lines. The regulatory sequence involved in HLA-A gene repression was further mapped to a proximal regulatory element within the -107 to +2 ATG region of the promoter. We show that the HLA-A promoter activity cannot be induced by interferon-gamma (IFN-gamma) and that exogenous MHC class II transactivator CIITA is able to induce HLA class I promoter activity in these cells. Stringent transcriptional regulatory mechanisms, implicating the lack of basal and IFN-gamma-inducible class I promoter activity, are thus involved in the downregulation of HLA-A expression in JEG-3 and BeWo trophoblast-derived choriocarcinoma cells.
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64
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Bertrandy S, Burlet P, Clermont O, Huber C, Fondrat C, Thierry-Mieg D, Munnich A, Lefebvre S. The RNA-binding properties of SMN: deletion analysis of the zebrafish orthologue defines domains conserved in evolution. Hum Mol Genet 1999; 8:775-82. [PMID: 10196366 DOI: 10.1093/hmg/8.5.775] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a common autosomal recessive disorder that results in the degeneration of spinal motor neurons. SMA is caused by alterations of the survival motor neuron ( SMN ) gene which encodes a novel protein of hitherto unclear function. The SMN protein associates with ribonucleoprotein particles involved in RNA processing and exhibits an RNA-binding capacity. We have isolated the zebrafish Danio rerio and nematode Caenorhabditis elegans orthologues and have found that the RNA-binding capacity is conserved across species. Purified recombinant SMN proteins from both species showed selectivity to poly(G) homopolymer RNA in vitro, similar to that of the human protein. Studying deletions of the zebrafish SMN protein, we defined an RNA-binding element in exon 2a, which is highly conserved across species, and revealed that its binding activity is modulated by protein domains encoded by exon 2b and exon 3. Finally, the deleted recombinant zebrafish protein mimicking an SMA frameshift mutation showed a dramatic change in vitro in the formation of the RNA-protein complexes. These observations indicate that the RNA-binding capacity of SMN is an evolutionarily conserved function and further support the view that defects in RNA metabolism most likely account for the pathogenesis of SMA.
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65
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Cabestre FA, Lefebvre S, Moreau P, Rouas-Friess N, Dausset J, Carosella ED, Paul P. HLA-G expression: immune privilege for tumour cells? Semin Cancer Biol 1999; 9:27-36. [PMID: 10092548 DOI: 10.1006/scbi.1998.0104] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The non-classical class I antigen HLA-G has been shown to play a role in foeto-maternal tolerance. It interacts with inhibitory receptors to down-regulate natural killer and T cell cytotoxic functions. We here report our investigations on HLA-G expression in melanoma cells and its implication in the induction of immune tolerance to tumours. We provide the first evidence that both malignant human melanoma cell lines and ex vivo biopsies can exhibit high levels of HLA-G transcription with differential HLA-G isoform transcription and protein expression patterns. We further demonstrated that melanoma cells that express HLA-G inhibit NK cytolysis. We thus propose that HLA-G expression may impede the elimination of malignant cells by anti-tumour immune effector cells, constituting a newly described mechanism by which tumour cells may evade immunosurveillance.
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66
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Moreau P, Lefebvre S, Gourand L, Dausset J, Carosella ED, Paul P. Specific binding of nuclear factors to the HLA-G gene promoter correlates with a lack of HLA-G transcripts in first trimester human fetal liver. Hum Immunol 1998; 59:751-7. [PMID: 9831130 DOI: 10.1016/s0198-8859(98)00081-0] [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: 11/20/2022]
Abstract
The nonclassical MHC class I HLA-G antigen is expressed in cytotrophoblasts during pregnancy and may play a role in inhibiting lysis by maternal natural killer cells. HLA-G gene transcription was analyzed in human fetal liver of 6-8 wk of gestation, a development stage where classical HLA class I expression is very reduced. We demonstrated that HLA-G transcription is undetectable in these cells and we investigated the molecular mechanisms that control the lack of HLA-G gene transcription. We compared protein interactions of nuclear extracts from first trimester fetal livers, YT2C2-PR (HLA-G negative) and JEG-3 (HLA-G positive) cell lines to a 244-bp EcoR I/Hind III DNA region located 1.2 kb from the HLA-G gene, previously shown to direct HLA-G expression in transgenic mouse placenta. A strong specific C7-factor was specifically detected in first trimester fetal liver that could account for the inhibition of HLA-G transcription. Interaction of C7-factor and cell-specific factors previously detected in YT2C2 cell line (C5, C6) with two distinct regulatory regions identify this 244-bp EcoR I/Hind III fragment as a putative target for inhibition of HLA-G transcription.
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67
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Burlet P, Huber C, Bertrandy S, Ludosky MA, Zwaenepoel I, Clermont O, Roume J, Delezoide AL, Cartaud J, Munnich A, Lefebvre S. The distribution of SMN protein complex in human fetal tissues and its alteration in spinal muscular atrophy. Hum Mol Genet 1998; 7:1927-33. [PMID: 9811937 DOI: 10.1093/hmg/7.12.1927] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterized by degeneration of motor neurons of the spinal cord and muscular atrophy. SMA is caused by alterations to the survival of motor neuron (SMN) gene, the function of which has hitherto been unclear. Here, we present immunoblot analyses showing that normal SMN protein expression undergoes a marked decay in the postnatal period compared with fetal development. Morphological and immunohistochemical analyses of the SMN protein in human fetal tissues showed a general distribution in the cytoplasm, except in muscle cells, where SMN protein was immunolocalized to large cytoplasmic dot-like structures and was tightly associated with membrane-free heavy sedimenting complexes. These cytoplasmic structures were similar in size to gem. The SMN protein was markedly deficient in tissues derived from type I SMA fetuses, including skeletal muscles and, as previously shown, spinal cord. While our data do not help decide whether SMA results from impaired SMN expression in spinal cord, skeletal muscle or both, they suggest a requirement for SMN protein during embryo-fetal development.
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68
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Lefebvre S, Bürglen L, Frézal J, Munnich A, Melki J. The role of the SMN gene in proximal spinal muscular atrophy. Hum Mol Genet 1998; 7:1531-6. [PMID: 9735373 DOI: 10.1093/hmg/7.10.1531] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Childhood spinal muscular atrophy (SMA) is a common recessive autosomal disorder that results in degeneration of lower motor neurons. The identification of the disease gene, Survival of Motor Neuron (SMN), was a major advance in understanding the molecular basis underlying this devastating neuromuscular disease. This finding has greatly improved the genetic counselling of SMA families. Recently, biochemical studies demonstrated its involvement in the biogenesis of spliceosomal snRNPs, suggesting a critical role of SMN in RNA processing. Surprisingly, other studies showed a putative role of SMN in an anti-apoptotic pathway involving Bcl-2. The function of SMN protein is not fully understood. These observations emphasized the difficulty in elucidating the function of any novel protein. Therefore, multidisciplinary approaches are required to understand the pathogenesis of SMA.
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69
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Capitan MJ, Lefebvre S, Traverse A, Paúl A, Odriozola JA. Anomalous scattering study of oxide scales formed at 1173 K on surface modified stainless steel. ACTA ACUST UNITED AC 1998. [DOI: 10.1039/a802233j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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70
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Lefebvre S, Burlet P, Liu Q, Bertrandy S, Clermont O, Munnich A, Dreyfuss G, Melki J. Correlation between severity and SMN protein level in spinal muscular atrophy. Nat Genet 1997; 16:265-9. [PMID: 9207792 DOI: 10.1038/ng0797-265] [Citation(s) in RCA: 792] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterized by degeneration of motor neurons of the spinal cord. Three different forms of childhood SMA have been recognized on the basis of age at onset and clinical course: Werdnig-Hoffmann disease (type-1), the intermediate form (type-II) and Kugelberg-Welander disease (type-III). A gene termed 'survival of motor neuron' (SMN) has been recognized as the disease-causing gene in SMA. SMN encodes a protein located within a novel nuclear structure and interacts with RNA-binding proteins. To elucidate the molecular mechanism underlying the pathogenesis of the disease, we examined the expression of the SMN gene in both controls and SMA patients by western blot and immunohistochemical analyses using antibodies raised against the SMN protein. The present study shows a marked deficiency of the SMN protein in SMA.
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71
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Viollet L, Bertrandy S, Bueno Brunialti AL, Lefebvre S, Burlet P, Clermont O, Cruaud C, Guénet JL, Munnich A, Melki J. cDNA isolation, expression, and chromosomal localization of the mouse survival motor neuron gene (Smn). Genomics 1997; 40:185-8. [PMID: 9070939 DOI: 10.1006/geno.1996.4551] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Spinal muscular atrophy (SMA) is a frequent autosomal recessive disease in human characterized by degeneration of motor neurons of the spinal cord. The genomic region containing the defective gene (5q13) is particularly unstable and prone to large-scale deletions whose characterization led to the identification of the survival motor neuron (SMN) gene, the SMA determining gene encoding a hitherto unknown protein. As an initial step toward the generation of a murine model for SMA, we identified and characterized a full-length murine Smn cDNA. The coding sequence of the mouse Smn gene was found to be 82% identical, at the amino acid level, with the human SMN coding sequence. The Smn locus was mapped to the segment of mouse chromosome 13 exhibiting conservation of synteny with human chromosome 5q11-q23, which contains the SMN gene. However, no evidence for a duplication of the Smn gene was found in the mouse, suggesting that the duplication reported in human is a recent evolutionary event.
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72
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Bürglen L, Seroz T, Miniou P, Lefebvre S, Burlet P, Munnich A, Pequignot EV, Egly JM, Melki J. The gene encoding p44, a subunit of the transcription factor TFIIH, is involved in large-scale deletions associated with Werdnig-Hoffmann disease. Am J Hum Genet 1997; 60:72-9. [PMID: 8981949 PMCID: PMC1712562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mutations of the survival motor neurone gene (SMN) are associated with spinal muscular atrophy (SMA), a frequent lethal autosomal recessive disorder. In spite of this, no phenotype-genotype correlation was observed, since the SMN gene is lacking in the majority of patients affected with either the severe form (type I) or the milder forms (types II and III). Here, we show that the gene encoding p44, a subunit of the basal transcription factor TFIIH, is duplicated in the SMA region and that the p44 gene products (p44t and p44c) differ by three amino acid changes. Gene analysis of a total of 94 unrelated SMA patients revealed that the p44t gene is involved in large-scale deletions associated with Werdnig-Hoffmann disease (type I). The TFIIH polypeptide composition as well as transcription and DNA repair activities are normal in patients lacking the p44t gene on both mutant chromosomes, suggesting that the p44t gene is not critical for the development of SMA.
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73
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Bürglen L, Amiel J, Viollet L, Lefebvre S, Burlet P, Clermont O, Raclin V, Landrieu P, Verloes A, Munnich A, Melki J. Survival motor neuron gene deletion in the arthrogryposis multiplex congenita-spinal muscular atrophy association. J Clin Invest 1996; 98:1130-2. [PMID: 8787675 PMCID: PMC507534 DOI: 10.1172/jci118895] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The survival motor neuron (SMN) gene was lacking in 6/12 patients with arthrogryposis multiplex congenita (AMC) associated with spinal muscular atrophy (SMA). Neither point mutation in the SMN gene nor evidence for linkage to chromosome 5q13 were found in the other patients. Hitherto, arthrogryposis was regarded as an exclusion criterion in SMA. Our data strongly suggest that AMC of neurogenic origin is genetically heterogeneous, with a subgroup being allelic to SMA. Absence or interruption of the SMN gene in the AMC-SMA association will make the diagnosis easier and genetic counselling will now become feasible.
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Burlet P, Bürglen L, Clermont O, Lefebvre S, Viollet L, Munnich A, Melki J. Large scale deletions of the 5q13 region are specific to Werdnig-Hoffmann disease. J Med Genet 1996; 33:281-3. [PMID: 8730281 PMCID: PMC1050575 DOI: 10.1136/jmg.33.4.281] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Spinal muscular atrophy (SMA) is characterised by degeneration of anterior horn cells of the spinal cord and represents the second most common, lethal, autosomal recessive disorder after cystic fibrosis. Based on the criteria of the Internatinal SMA Consortium, childhood SMAs are classified into type I (Werdnig-Hoffmann disease), type II (intermediate form), and type III (Kugelberg-Welander disease). Recently, two genes have been found to be associated with SMA. The survival motor neurone gene (SMN) is an SMA determining gene as it is absent in 98.6% of patients. A second gene, XS2G3, or the highly homologous neuronal apoptosis inhibitory protein gene (NAIP) have been found to be more frequently deleted in type I than in the milder forms (types II and III). We investigated the correlation between the clinical phenotype and the genotype at this loci. A total of 106 patients were classified into type I (44), type II (31), and type III (31) and analysed using SMN, markers C212 and C272, and NAIP mapping upstream and downstream from SMN respectively. The combined analysis of all markers showed a large proportion of type I patients (43%) carried deletions of both SMN and its flanking markers (C212/272) and NAIP exon 5), as compared with none of the patients with type II or III SMA. The presence of large scale deletions involving these loci is specific to Werdnig-Hoffman disease (type I) and allows one to predict the severity of the disease in our series.
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Bürglen L, Lefebvre S, Clermont O, Burlet P, Viollet L, Cruaud C, Munnich A, Melki J. Structure and organization of the human survival motor neurone (SMN) gene. Genomics 1996; 32:479-82. [PMID: 8838816 DOI: 10.1006/geno.1996.0147] [Citation(s) in RCA: 174] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Spinal muscular atrophies (SMA) are characterized by degeneration of the anterior horn cells of the spinal cord and represent the second most common fatal autosomal-recessive disorder after cystic fibrosis. We have previously identified the survival motor neurone gene (SMN), a SMA-determining gene in the 5q13 region encoding a hitherto unknown protein. In this report, we describe the organization and structure of SMN. The gene is approximately equal to 20 kb in length and consists of nine exons. Sequence data of the 5' end of the gene show that the dinucleotide repeat C272 is close to several putative binding sites for transcription factors, which will help to characterize the regulation of the SMN and CBCD541 gene expression. The availability of the human SMN and its highly homologous counterpart (CBCD541) gene structures and exon-intron boundaries will hopefully speed up the characterization of SMN gene mutations in SMA.
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