title: Nox1 is involved in p53 deacetylation and suppression of its transcriptional activity and apoptosis.
abstract: HIPK2 is a stress-induced kinase and a transcriptional corepressor that functionally cooperates with p53 to suppress cancer. Activation of the p53 proapoptotic function requires a cascade of phosphorylations and acetylations, and HIPK2 takes part in both modifications in that it phosphorylates p53 Ser46 and induces p53 Lys382 acetylation. Here, to further investigate the role of HIPK2 in p53 activation, we started with the finding that HIPK2 inhibition upregulated Nox1, a homolog of the catalytic subunit of the superoxide-generating NADPH oxidase, involved in tumor progression and ROS production. We found that Nox1 inhibited p53 Lys382 acetylation, which is a target of SIRT1 deacetylase, and impaired p53 proapoptotic transcriptional activity. By the use of either small interfering RNAs to target SIRT1 or the SIRT1 inhibitor nicotinamide we found that Nox1-dependent inhibition of p53 transcriptional activity was SIRT1-dependent. Thus, Nox1 was unable to inhibit p53 when coexpressed with a SIRT1 deacetylase-defective mutant (SIRT1HY), suggesting a link between Nox1 and SIRT1 activity. Finally, recovery of HIPK2 function downregulated Nox1 expression with rescue of p53 Lys382 acetylation and p53 activity. Together, our findings indicate that Nox1 upregulation may activate SIRT1 and inhibit p53 and that Lys382 is important for p53 proapoptotic function.
authors.affiliation: Department of Experimental Oncology, Molecular Oncogenesis Laboratory, National Cancer Institute Regina Elena, Rome, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Puca
authors.forename: Lavinia
authors.initials: L
authors.lastname: Nardinocchi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Starace
authors.forename: Gideon
authors.initials: G
authors.lastname: Rechavi
authors.forename: Ada
authors.initials: A
authors.lastname: Sacchi
authors.forename: David
authors.initials: D
authors.lastname: Givol
authors.forename: Gabriella
authors.initials: G
authors.lastname: D'Orazi
mesh_terms: D000107:Acetylation / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000096:biosynthesis* / Q000235:genetics; D009536:Niacinamide / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D056564:Sirtuin 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D050505:Mutant Proteins; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D009536:Niacinamide; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C402799:NOX1 protein, human; C115114:HIPK2 protein, human; D017346:Protein Serine-Threonine Kinases; C447939:SIRT1 protein, human; D056564:Sirtuin 1