Projet ANR-07-BLAN-0047 – Xist A-repeat : Role and mechanism of the Xist A-repeat element in X-chromosome inactivation
Programme : Blanc (BLANC) 2007
Année de financement : 2007
Coordinateur du projet : Monsieur Philip AVNER (INSTITUT PASTEUR)
Partenaires : Institut Pasteur; Université de Lorraine
Montant : 400000.0 euros
Date de début : 2007
Durée : 36 mois
Résumé : X-chromosome inactivation (XCI) ensures the dosage compensation of X-linked genes between the female (XX) and male (XY) mammals by a process of transcriptional inactivation which leads to the silencing of the thousand or so X-linked genes in the mouse. -  The Xist gene which encodes a 17 Kb spliced non-coding RNA that accumulates on, and coats the Xi elect is necessary for the spreading and stabilisation of the inactive state. Establishment of silencing involves the recruitment by the Xist molecule of a series of remodelling complexes that modify and stabilise the chromatin state of the X chromosome chosen for inactivation. -  The 420 nucleotides A-repeat, an evolutionarily highly conserved element within the Xist RNA, lying at the 5' end of the Xist molecule has been shown to be critically necessary for this silencing. This project aims at characterising the functions determined by the A-repeat region during the X-chromosome inactivation process. In a concerted research project the applicants propose to explore the recruitment by the A repeat region, of nucleoprotein complexes associated with the heterochromatinisation of the inactive X chromosome using a strategy of affinity purification with subsequent identification of interacting proteins by mass spectroscopy. Approaches undertaken to confirm the functional importance of retained candidates will include RNA interference and analysis of the association of candidates with the inactive X chromosome during the onset of X-inactivation provoked by ES cell differentiation. Mutagenesis of the A-repeat region in vivo using a recombinase-mediated cassette exchange strategy will be used to generate a series of A repeat mutations that will be used both to refine the interpretation of the results of the proteomics approach and to explore other facets of the role of the A repeat in random X-inactivation.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        ...