Human ARF binds E2F1 and inhibits its transcriptional activity

Béatrice Eymin (1, 2) , Lucie Karayan (3) , Paule Séité (3) , Christian Brambilla (1, 2) , Elisabeth Brambilla (1, 2) , Christian-Jacques Larsen (3) , Sylvie Gazzeri (1, 2)

1 EA2021 - Groupe de Recherche sur le Cancer du Poumon
2 Institut Albert Bonniot - Equipe INSERM 9924 [La Tronche]
3 ESA 6031 - Laboratoire Immunologie et Immunopathologie

The INK4a/ARF locus which is frequently inactivated in human tumours encodes two different tumour suppressive proteins, p16(INK4a) and ARF. p16(INK4a) is a major component of the RB pathway. ARF is part of an ARF-mdm2-p53 network that exerts a negative control on hyperproliferative signals emanating from oncogenic stimuli. Among these is the transcription factor E2F1, a final effector of the RB pathway, that induces ARF expression. Recent data suggest that ARF function is not restricted to the p53 pathway. However, ARF target(s) implicated in this p53-independent function remains to be identified. We show that ARF is able to inhibit the proliferation of human cell lines independently of their p53 status. In this context, we demonstrate that ARF interacts physically with E2F1 and inhibits its transcriptional activity. Moreover, we show that mdm2 is required for the modulation of E2F1 activity by ARF. Beside the well-known p53 and mdm2 partners, these results identify E2F1 as a new ARF target. Thus, ARF can be viewed as a dual-acting tumour suppressor protein in both the p53 and RB pathways, further emphasizing its role in tumour surveillance.

Mots clés: ARF; E2F1; mdm2; tumor suppressor; transcription regulation

Domaines: Sciences du Vivant [q-bio]; Biologie cellulaire

Béatrice Eymin, Lucie Karayan, Paule Séité, Christian Brambilla, Elisabeth Brambilla, et al.. Human ARF binds E2F1 and inhibits its transcriptional activity: ARF inhibits E2F1 activity. Oncogene, 2001, 20 (9), pp.1033-41. ⟨10.1038/sj.onc.1204220⟩. ⟨inserm-02345407⟩