title: Regulation of E2F-1 after DNA damage by p300-mediated acetylation and ubiquitination.
abstract: Here we report a novel, noncompetitive mechanism that links acetylation and ubiquitination, in which the association of transcription factor E2F-1 with the cellular coactivator and acetyltransferase p300 determines its acetylation and subsequent ubiquitination. By using an antibody specifically recognizing the acetylated form of E2F-1 (AcE2F-1), we found that, after DNA damage, AcE2F-1 accumulates in the cells in a time-dependent manner, and that acetylation is increased by the expression of p300. Remarkably, the same DNA damaging conditions also induce the accumulation of ubiquitinated E2F-1, an event that is again markedly stimulated by p300 overexpression. The effects of p300 on E2F-1 ubiquitination require the integrity of the HAT domain of p300 and of the three acetylated lysines in E2F-1. Of note, p300-induced E2F-1 ubiquitination does not depend on the p45Skp2 E3 ligase, since it does not extend to other p45Skp2 targets and also occurs with an E2F-1 mutant devoid of the p45Skp2-binding domain but still retaining the acetylated region. Finally, p300-induced E2F-1 ubiquitination is not influenced by RB.
authors.affiliation: Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Galbiati
authors.forename: Ramiro
authors.initials: R
authors.lastname: Mendoza-Maldonado
authors.forename: Maria Ines
authors.initials: MI
authors.lastname: Gutierrez
authors.forename: Mauro
authors.initials: M
authors.lastname: Giacca
mesh_terms: D000107:Acetylation; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004249:DNA Damage / Q000187:drug effects; D050687:E2F1 Transcription Factor / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008239:Lysine / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism*; D050880:p300-CBP Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D050687:E2F1 Transcription Factor; D025801:Ubiquitin; D050880:p300-CBP Transcription Factors; D044843:SKP Cullin F-Box Protein Ligases; D008239:Lysine