title: hSirT1-dependent regulation of the PCAF-E2F1-p73 apoptotic pathway in response to DNA damage.
abstract: The NAD(+)-dependent histone deacetylase hSirT1 regulates cell survival and stress responses by inhibiting p53-, NF-kappaB-, and E2F1-dependent transcription. Here we show that the hSirT1/PCAF interaction controls the E2F1/p73 apoptotic pathway. hSirT1 represses E2F1-dependent P1p73 promoter activity in untreated cells and inhibits its activation in response to DNA damage. hSirT1, PCAF, and E2F1 are corecruited in vivo on theP1p73 promoter. hSirT1 deacetylates PCAF in vitro and modulates PCAF acetylation in vivo. In cells exposed to apoptotic DNA damage, nuclear NAD(+) levels decrease and inactivate hSirT1 without altering the hSirT1 interaction with PCAF and hSirT1 binding to the P1p73 promoter. The reactivation of hSirT1 by pyruvate that increases the [NAD(+)]/[NADH] ratio completely abolished the DNA damage-induced activation of TAp73 expression, thus linking the modulation of chromatin-bound hSirT1 deacetylase activity by the intracellular redox state with P1p73 promoter activity. The release of PCAF from hSirT1 repression favors the assembly of transcriptionally active PCAF/E2F1 complexes onto the P1p73 promoter and p53-independent apoptosis. Our results identify hSirT1 and PCAF as potential targets to modulate tumor cell survival and chemoresistance irrespective of p53 status.
authors.affiliation: Laboratory of Gene Expression, Fondazione A Cesalpino, Viale del Policlinico 155, 00161 Rome, Italy.
authors.forename: Natalia
authors.initials: N
authors.lastname: Pediconi
authors.forename: Francesca
authors.initials: F
authors.lastname: Guerrieri
authors.forename: Stefania
authors.initials: S
authors.lastname: Vossio
authors.forename: Tiziana
authors.initials: T
authors.lastname: Bruno
authors.forename: Laura
authors.initials: L
authors.lastname: Belloni
authors.forename: Valeria
authors.initials: V
authors.lastname: Schinzari
authors.forename: Cecilia
authors.initials: C
authors.lastname: Scisciani
authors.forename: Maurizio
authors.initials: M
authors.lastname: Fanciulli
authors.forename: Massimo
authors.initials: M
authors.lastname: Levrero
mesh_terms: D000107:Acetylation; D017209:Apoptosis; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D050687:E2F1 Transcription Factor / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D056564:Sirtuin 1; D037761:Sirtuins / Q000502:physiology*; D014158:Transcription, Genetic; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D050880:p300-CBP Transcription Factors / Q000378:metabolism*; D000099224:p300-CBP-Associated Factor
chemical_list: D004268:DNA-Binding Proteins; D050687:E2F1 Transcription Factor; D009687:Nuclear Proteins; D056564:Sirtuin 1; D037761:Sirtuins; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C493753:E2F1 protein, human; C000606460:TP73 protein, human; C447939:SIRT1 protein, human