G Gourdon

Publications (11)73.56 Total impact

• Article: Mice transgenic for the human myotonic dystrophy region with expanded CTG repeats display muscular and brain abnormalities.

  H Seznec, O Agbulut, N Sergeant, C Savouret, A Ghestem, N Tabti, J C Willer, L Ourth, C Duros, E Brisson, C Fouquet, G Butler-Browne, A Delacourte, C Junien, G Gourdon
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  ABSTRACT: The autosomal dominant mutation causing myotonic dystrophy (DM1) is a CTG repeat expansion in the 3'-UTR of the DM protein kinase (DMPK) gene. This multisystemic disorder includes myotonia, progressive weakness and wasting of skeletal muscle and extramuscular symptoms such as cataracts, testicular atrophy, endocrine and cognitive dysfunction. The mechanisms underlying its pathogenesis are complex. Recent reports have revealed that DMPK gene haploinsufficiency may account for cardiac conduction defects whereas cataracts may be due to haploinsufficiency of the neighboring gene, the DM-associated homeobox protein (DMAHP or SIX5) gene. Furthermore, mice expressing the CUG expansion in an unrelated mRNA develop myotonia and myopathy, consistent with an RNA gain of function. We demonstrated that transgenic mice carrying the CTG expansion in its human DM1 context (>45 kb) and producing abnormal DMPK mRNA with at least 300 CUG repeats, displayed clinical, histological, molecular and electrophysiological abnormalities in skeletal muscle consistent with those observed in DM1 patients. Like DM1 patients, these transgenic mice show abnormal tau expression in the brain. These results provide further evidence for the RNA trans-dominant effect of the CUG expansion, not only in muscle, but also in brain.
  Human Molecular Genetics 11/2001; 10(23):2717-26. · 7.64 Impact Factor
• Article: Defective satellite cells in congenital myotonic dystrophy.

  D Furling, L Coiffier, V Mouly, J P Barbet, J L St Guily, K Taneja, G Gourdon, C Junien, G S Butler-Browne
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  ABSTRACT: In this study we have developed an in vitro cell culture system which displays the majority of the defects previously described for congenital myotonic dystrophy (CDM) muscle in vivo. Human satellite cells were isolated from the quadriceps muscles of three CDM fetuses with different clinical severity. By Southern blot analysis all three cultures were found to have approximately 2300 CTG repeats. This CTG expansion was found to progressively increase in size during the proliferative life span, confirming an instability of this triplet in skeletal muscle cells. The CDM myoblasts and myotubes also showed abnormal retention of mutant RNA in nuclear foci, as well as modifications in their myogenic program. The proliferative capacity of the CDM myoblasts was reduced and a delay in fusion, differentiation and maturation was observed in the CDM cultures compared with unaffected myoblast cultures. The clinical severity and delayed maturation observed in the CDM fetuses were closely reflected by the phenotypic modifications observed in vitro. Since the culture conditions were the same, this suggests that the defects we have described are intrinsic to the program expressed by the myoblasts in the absence of any trophic factors. Altogether, our results demonstrate that satellite cells are defective in CDM and are probably implicated in the delay in maturation and muscle atrophy that has been described previously in CDM fetuses.
  Human Molecular Genetics 10/2001; 10(19):2079-87. · 7.64 Impact Factor
• Article: Transgenic mice carrying large human genomic sequences with expanded CTG repeat mimic closely the DM CTG repeat intergenerational and somatic instability.

  H Seznec, A S Lia-Baldini, C Duros, C Fouquet, C Lacroix, H Hofmann-Radvanyi, C Junien, G Gourdon
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  ABSTRACT: Myotonic dystrophy (DM) is caused by a CTG repeat expansion in the 3'UTR of the DM protein kinase (DMPK) gene. A very high level of instability is observed through successive generations and the size of the repeat is generally correlated with the severity of the disease and with age at onset. Furthermore, tissues from DM patients exhibit somatic mosaicism that increases with age. We generated transgenic mice carrying large human genomic sequences with 20, 55 or >300 CTG, cloned from patients from the same affected DM family. Using large human flanking sequences and a large amplification, we demonstrate that the intergenerational CTG repeat instability is reproduced in mice, with a strong bias towards expansions and with the same sex- and size-dependent characteristics as in humans. Moreover, a high level of instability, increasing with age, can be observed in tissues and in sperm. Although we did not observe dramatic expansions (or 'big jumps' over several hundred CTG repeats) as in congenital forms of DM, our model carrying >300 CTG is the first to show instability so close to the human DM situation. Our three models carrying different sizes of CTG repeat provide insight on the different factors modulating the CTG repeat instability.
  Human Molecular Genetics 05/2000; 9(8):1185-94. · 7.64 Impact Factor
• Source

  Available from: Ralf Krahe

  Article: New nomenclature and DNA testing guidelines for myotonic dystrophy type 1 (DM1)

  I Gonzalez, N Ohsawa, R H Singer, M Devillers, T Ashizawa, A Balasubramanyam, T A Cooper, M Khajavi, A.S. Lia-Baldini, G. Miller, [......], S Michalowski, H Moore, M. Hamshere, Z. Korade, C A Thornton, H. Jaeger, F. Lehmann, J R Moorman, J P Mounsey, M S Mahadevan
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  ABSTRACT: The International Myotonic Dystrophy Consortium (IDMC) * Myotonic dystrophy (DM; OMIM 160900, also known as dystrophia myotonica, myotonia atrophica and Steinert disease) is an autosomal dominant myotonic myopathy associated with abnormalities of other organs, including eyes, heart, endocrine system, cen-tral and peripheral nervous systems, gastrointestinal organs, bone, and skin. 1 The mutation underlying DM is an expansion of an unstable cytosine-thymine-guanine (CTG) trinucleotide repeat in the 3 un-translated region of the myotonic dystrophy protein kinase (DMPK) gene in chromosome 19q13.3. 2-4 In 1994, Thornton et al. 5 described an autosomal domi-nant disorder similar to DM without CTG repeat expansion at the DM locus. Ricker et al. 6 named this disease "proximal myotonic myopathy" (PROMM; OMIM 600109) because of predominantly proximal muscle weakness without atrophy as opposed to the distal muscle involvement seen in DM. Subse-quently, Meola et al. 7 described a variant of PROMM with unusual myotonic and myopathic features, which they named "proximal myotonic myopathy syndrome," and Udd et al. 8 described a PROMM-like family with dystrophic features, which they named "proximal myotonic dystrophy" (PDM). Researchers at the University of Minnesota 9,10 found another mul-tisystemic myotonic disorder that closely resembles DM with distal muscle weakness but no CTG repeat expansion. Because of the close phenotypic resem-blance to DM, they called this disease "myotonic dys-trophy type 2" (DM2; OMIM 602668). In 1998, Ranum et al. 9 assigned the DM2 locus to chromo-some 3q in a large kindred. Shortly after that, Ricker et al. 11 found that the majority of German PROMM families show linkage to the DM2 locus. PDM was also mapped to this region (Krahe and Udd, personal communication, 1999). Whether PROMM, PDM, and DM2 represent different phenotypic expressions of a disease caused by the same mutation or if they are allelic disorders remains to be determined. It is also possible that these disorders are caused by muta-tions in different genes that are closely linked in the chromosome 3q region. 12 Furthermore, the disease loci in some typical PROMM families 11 and other families with multisystemic myotonic disorders have been excluded from both DM and DM2 loci. Because of the genetic and phenotypic heterogeneity in this group of disorders, it became necessary to establish a new nomenclature foreseeing the future discovery of new disease loci and phenotypic variability. The phenotypic resemblance between DM (map-ping to 19q13.3) and PROMM/PDM/DM2 (mapping to 3q21) complicates the diagnosis of these disorders. Consequently, genetic testing must play an impor-tant role in making an accurate diagnosis. While genetic testing for diseases linked to the DM2 locus is currently only possible by linkage analysis (which is not commercially available), DNA testing for the diagnosis of DM has been available since the discov-ery of the expanded CTG repeat as the genetic muta-tion in 1992. 2-4 The increasing use of DNA testing for DM generates many questions regarding the indica-tions and interpretations of the test with concerns of potential misuse. For accurate determination of the mutation, standardized methods readily available in molecular genetics laboratories are desirable. Confi-dentiality of the results and the fate of the DNA samples after the test are also important issues. At the Second International Myotonic Dystrophy Consortium (IDMC) Conference held on April 21 through 23, 1999 in Research Triangle, NC, 83 DM investigators reached a consensus for a new nomen-clature for myotonic dystrophies. The Nomenclature Committee of the Human Genome Organization (HUGO) has approved the new nomenclature. During the Conference, IDMC also discussed the genetic test-ing issues of DM and developed guidelines. Consensus for the new nomenclature:
  Neurology 01/2000; · 8.31 Impact Factor
• Article: Somatic instability of the CTG repeat in mice transgenic for the myotonic dystrophy region is age dependent but not correlated to the relative intertissue transcription levels and proliferative capacities.

  A S Lia, H Seznec, H Hofmann-Radvanyi, F Radvanyi, C Duros, C Saquet, M Blanche, C Junien, G Gourdon
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  ABSTRACT: A (CTG)nexpansion in the 3'-untranslated region (UTR) of the DM protein kinase gene ( DMPK ) is responsible for causing myotonic dystrophy (DM). Major instability, with very large expansions between generations and high levels of somatic mosaicism, is observed in patients. There is a good correlation between repeat size (at least in leucocytes), clinical severity and age of onset. The trinucleotide repeat instability mechanisms involved in DM and other human genetic diseases are unknown. We studied somatic instability by measuring the CTG repeat length at several ages in various tissues of transgenic mice carrying a (CTG)55expansion surrounded by 45 kb of the human DM region, using small-pool PCR. These mice have been shown to reproduce the intergenerational and somatic instability of the 55 CTG repeat suggesting that surrounding sequences and the chromatin environment are involved in instability mechanisms. As observed in some of the tissues of DM patients, there is a tendency for repeat length and somatic mosaicism to increase with the age of the mouse. Furthermore, we observed no correlation between the somatic mutation rate and tissue proliferation capacity. The somatic mutation rates in different tissues were also not correlated to the relative inter-tissue difference in transcriptional levels of the three genes (DMAHP , DMPK and 59) surrounding the repeat.
  Human Molecular Genetics 09/1998; 7(8):1285-91. · 7.64 Impact Factor
• Article: Intriguing association between disease associated unstable trinucleotide repeat and CpG island.

  G Gourdon, P Dessen, A S Lia, C Junien, H Hofmann-Radvanyi
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  ABSTRACT: Expansion of (C+G)-rich trinucleotide repeats has been shown to be associated with several autosomal or X-linked genetic diseases and/or fragile sites. By analysing the sequences available in the databases, we found, in a significant proportion of triplet associated genes or fragile sites (11/12), a CpG island close to the trinucleotide repeat. This association led us to assume that flanking regions and chromatin structure near the triplets might play a role in repeat instability.
  Annales de Génétique 02/1997; 40(2):73-7.
• Source

  Available from: hematologylibrary.org

  Article: The mouse alpha-globin locus regulatory element.

  G Gourdon, J A Sharpe, D R Higgs, W G Wood
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  ABSTRACT: We have identified and cloned the major alpha globin locus regulatory element in the mouse (m alpha RE). This element shows a high level of sequence homology to its human counterpart (HS -40) and lies between the same two exons of an upstream, widely expressed gene in both species. Footprinting and band shift studies of the core element show conservation of many (but not all) of the protein binding sites identified as functionally important in HS -40. The functional equivalence of the mouse element was shown by attaching it to a human alpha globin gene and examining expression in transgenic mice. Readily detectable levels of human alpha mRNA were produced in these mice but they were lower than the endogenous gene expression and did not show copy number dependence. These results suggest that sequences additional to this major regulatory element may be necessary to obtain complete regulation of the alpha globin genes in both species.
  Blood 08/1995; 86(2):766-75. · 9.90 Impact Factor
• Source

  Available from: nih.gov

  Article: Analysis of a 70 kb segment of DNA containing the human zeta and alpha-globin genes linked to their regulatory element (HS-40) in transgenic mice.

  G Gourdon, J A Sharpe, D Wells, W G Wood, D R Higgs
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  ABSTRACT: We have ligated two cosmids through an oligonucleotide linker to produce a single fragment spanning 70 kb of the human alpha-globin cluster, in which the alpha-like globin genes (zeta 2, alpha 2 and alpha 1), their regulatory element (HS-40) and erythroid-specific DNase I hypersensitive sites accurately retain their normal genomic organization. The zeta (embryonic) and alpha (embryonic, fetal and adult) globin genes were expressed in all 17 transgenic embryos. Similarly, all fetal and adult mice from seven transgenic lines that contained one or more copies of the fragment, produced up to 66% of the level of endogenous mouse alpha-globin mRNA. However, as for smaller constructs containing these elements, human alpha-globin expression was not copy number dependent and decreased by 1.5-9.0 fold during development. These findings suggest that either it is not possible to obtain full regulation of human alpha-globin expression in transgenic mice or, more likely, that additional alpha-globin regulatory elements lie beyond the 70 kb segment of DNA analysed.
  Nucleic Acids Research 11/1994; 22(20):4139-47. · 8.03 Impact Factor
• Source

  Available from: hematologylibrary.org

  Article: Role of upstream DNase I hypersensitive sites in the regulation of human alpha globin gene expression.

  J A Sharpe, R J Summerhill, P Vyas, G Gourdon, D R Higgs, W G Wood
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  ABSTRACT: Erythroid-specific DNase 1 hypersensitive sites have been identified at the promoters of the human alpha-like genes and within the region from 4 to 40 kb upstream of the gene cluster. One of these sites, HS-40, has been shown previously to be the major regulator of tissue-specific alpha-globin gene expression. We have now examined the function of other hypersensitive sites by studying the expression in mouse erythroleukemia (MEL) cells of various fragments containing these sites attached to HS-40 and an alpha-globin gene. High level expression of the alpha gene was observed in all cases. When clones of MEL cells bearing a single copy of the alpha-globin gene fragments were examined, expression levels were similar to those of the endogenous mouse alpha genes and similar to MEL cells bearing beta gene constructs under the control of the beta-globin locus control region. However, there was no evidence that the additional hypersensitive sites increased the level of expression or conferred copy number dependence on the expression of a linked alpha gene in MEL cells.
  Blood 10/1993; 82(5):1666-71. · 9.90 Impact Factor
• Article: Identification of GATA-1 and NF-E2 binding sites in the flanking regions of the human alpha-globin genes.

  G Gourdon, F Morlé, J Roche, N Tourneur, V Joulain, J Godet
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  ABSTRACT: Some of the elements involved in the erythroid-specific transcriptional regulation of the human gamma- and beta-globin genes and located inside or in the immediate proximity of these genes have been identified as sequences which bind erythroid-specific factors. In the present study, we found two regions located within 1 kb in 5' to the alpha 2- and in 3' to the alpha 1-globin genes which contribute to the induction of human alpha-globin genes following erythroid differentiation in stable MEL transformants. By DNAse I footprinting and gel mobility shift assays, we identified several GATA-1 and one AP-1/NF-E2-binding sites located inside these regions. These results strengthen the idea that, like for all other globin genes, flanking regions contribute in vivo to the regulation of human alpha-globin gene expression.
  Acta Haematologica 02/1992; 87(3):136-44. · 1.35 Impact Factor
• Source

  Available from: nih.gov

  Article: Characterization of the major regulatory element upstream of the human alpha-globin gene cluster.

  A P Jarman, W G Wood, J A Sharpe, G Gourdon, H Ayyub, D R Higgs
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  ABSTRACT: The major positive regulatory activity of the human alpha-globin gene complex has been localized to an element associated with a strong erythroid-specific DNase I hypersensitive site (HS -40) located 40 kb upstream of the zeta 2-globin mRNA cap site. Footprint and gel shift analyses of the element have demonstrated the presence of four binding sites for the nuclear factor GATA-1 and two sites corresponding to the AP-1 consensus binding sequence. This region resembles one of the major elements of the beta-globin locus control region in its constitution and characteristics; this together with evidence from expression studies suggests that HS -40 is a primary element controlling alpha-globin gene expression.
  Molecular and Cellular Biology 10/1991; 11(9):4679-89. · 5.53 Impact Factor