Titre :
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A muscle specific cis-regulatory module unique to vertebrate a-tropomyosin genes (abstract : congrès international de Myologie, 2005)
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contenu dans :
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Auteurs :
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Congrès international de myologie 2005 (International Congress of Myology 2005; 9-13 mai 2005; Nantes, France) ;
Thiébaud P ;
Pasquet S ;
Naye F ;
Barillot W ;
Faucheux M ;
Faydou S ;
Thézé N
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Type de document :
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Article
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Année de publication :
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2005
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Pages :
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p. 79
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Langues:
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Anglais
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Mots-clés :
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actine
;
colloque
;
différenciation musculaire
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gène TPM3
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muscle lisse
;
muscle squelettique
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myocarde
;
myotube
;
régulation génique
;
Vertébrés
;
xénope
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Résumé :
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Communication n° 430. Development and differentiation of muscle cells is accompanied by the transcriptional activation of batteries of genes, some of them being expressed in a specific muscle lineage while others are expressed in all three lineages. We have previously shown that the a-tropomyosin (a-TM) gene that encodes an actin binding protein is expressed in the three muscle types during Xenopus amphibian development. How is the expression of the a-TM gene controlled in the different muscle types? Is its expression dependent on lineage specific regulatory sequences or is there a common cis-regulatory sequence that operates in the three muscle types? To address those questions we have undertaken the analysis of the transcriptional requirement of the a-TM gene promoter in skeletal, cardiac and smooth muscle cells. We have found that a 300bp proximal promoter of the gene is active in C2-7 myotubes, embryonic cardiomyocytes and several smooth muscle cell lines. Inside this 300bp region there is a 45bp sequence that is highly conserved between all vertebrate a-TM genes but absent from other TM genes. We have identified in this region a sequence, called M-CAT, that is essential to the activation of the promoter in the three muscle cell types. We have found that the protein TEF-1 was binding to this site and able to activate an a-TM reporter gene in smooth muscle cells. Moreover, we show here that the sub cellular localization of TEF-1 in smooth muscle ells (SMCs) depend on the differentiated status of the cells : in differentiated SMCs TEF1 is localised in the nucleus while there is re-localisation of the protein in the cytoplasm when cells are dedifferentiated. Together our data suggest that TEF1 is a major factor involved in the activation of the a-tropomyosin gene in the three muscle cell types and that it is part of a highly conserved cis-regulatory domain specific to vertebrates a-TM genes.
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