Show simple document record

dc.contributor.advisorLavigne, Pierrefr
dc.contributor.authorBeaulieu, Marie-Èvefr
dc.date.accessioned2014-09-09T18:39:32Z
dc.date.available2014-09-09T18:39:32Z
dc.date.created2011fr
dc.date.issued2011fr
dc.identifier.isbn9780494896563fr
dc.identifier.urihttp://hdl.handle.net/11143/5809
dc.description.abstractThe transcription factor c-Myc plays a central role in cell growth and proliferation owing to the large number of genes it transactivates or transrepresses and to the fact that these genes are in turn implicated in these cellular processes. Also, c-Myc's deregulation and/or overexpression contribute to most aspects of tumoral cellular biology. As a heterodimer with Max, c-Myc activates the transcription of genes leading to cell proliferation and represses the transcription of cytostatic genes such as p15[superscript ink4b] and p21[superscript CiP1]. In contrast to the transactivation mechanism, our current understanding of the transrépression by c-Myc is still incomplete, aside from the fact that an interaction with Miz-1 is essential. Coupling preliminary results from a collaboration with Martin Eilers' group to data obtained following a bioinformatics' approach to predict Miz-1 DNA binding, we were able to elaborate a now transrepression mechanism for c-Myc/Miz-1. In this mechanism, the c-Myc/Max heterodimer directly binds the noncanonical E-box sequences present in the promoters and provoke the supercoiling of DNA assisted by the interaction between c-Myc and Miz-1. This supercoiling impairs accessibility to the initiation site to the transcriptional machinery. This thesis aims at the study on a structural and biophysics viewpoint of the determinants for the specific heterodimerization and DNA binding by c-Myc and Max and the interaction between c-Myc and Miz-1 in order to validate our mechanistic model for the transrépression by c-Myc. In chapter 1, we present an overview of the actual knowledge on Myc and the repression model along with some of the results that led to its elaboration. Chapters 2 and 3 report the study of the structural determinants for the heterodimerization and E-box binding by the b-HLH-LZ domains of c-Myc and Max. Our model allows to predict that b-HLH-LZ peptides able to bind the E-box present in the repressed promoters without interaction with Miz-1 could reverse the inaccessibility and reactivate p15[superscript ink4b] and p21[superscript Cip1] expression in cancer cells where c-Myc is overexpressed.The results presented in this thesis will find application in the development of new inhibitors of c-Myc eventually leading to novel therapies to fight cancer.fr
dc.language.isofrefr
dc.publisherUniversité de Sherbrookefr
dc.rights© Marie-Eve Beaulieufr
dc.subjectCancerfr
dc.subjectLiaison à l'ADNfr
dc.subjectHétérodimérisationfr
dc.subjectTransrépressionfr
dc.subjectC-Mycfr
dc.titleBiologie structurale de c-Myc et Max : évidences pour un nouveau mécanisme de transrépression par Mycfr
dc.typeThèsefr
tme.degree.disciplinePharmacologiefr
tme.degree.grantorFaculté de médecine et des sciences de la santéfr
tme.degree.levelDoctoratfr
tme.degree.namePh.D.fr


Files in this document

Thumbnail

This document appears in the following Collection(s)

Show simple document record