Déterminants moléculaires non-apoptotiques de l'activité oncogénique de Bcl-xL : rôle de la monodéamidation de Bcl-xL

Abstract : Bcl-xL is an oncogene overexpressed in many types of cancer and which promotes cell survival by regulating two cellular processes : apoptosis and autophagy. We have recently identified a new form of this oncogene, which results from the deamidation of Asn52. This monodeamidated form is expressed under control conditions and is ubiquitously found in vitro and in vivo. Bcl-xL monodeamidation produces a mixture of proteins containing either an Asp residue or an IsoAsp residue in position 52. Our goal is to caracterise the functions of both species, and to determine how Bcl-xL monodeamidation modifies the survival functions of this oncogene. We have shown that the deamidomimetic mutant Bcl-xL N52DN66A retains the same anti-apoptotic function as the native protein, but exhibits enhanced autophagic activity and impaired clonogenic and tumorigenic properties in vitro, ex-vivo, and in vivo. We have studied certain of the mechanisms which can be involved in the regulation of autophagy and oncogenic properties of Bcl-xL such as mTor, Ras oncogene signaling pathway, metabolic activity measurement and stemness. We also implement in vitro assays to analyse the interactions established by isoAsp containing forms of Bcl-xL. Altogether our results support the view that deamidation regulates Bcl-xL oncogenic properties through apoptosis-independent mechanisms, and reinforce the importance of deciphering the non apoptotic functions of this protein to tackle its ability to sustain cell survival and drivecancer progression.
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Mohamad El Dhaybi. Déterminants moléculaires non-apoptotiques de l'activité oncogénique de Bcl-xL : rôle de la monodéamidation de Bcl-xL. Médecine humaine et pathologie. Université de Limoges, 2017. Français. ⟨NNT : 2017LIMO0034⟩. ⟨tel-01904459⟩

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