title: High Mobility Group A1 (HMGA1) proteins interact with p53 and inhibit its apoptotic activity.
abstract: HMGA gene overexpression and rearrangements are frequent in several tumours, but their oncogenic function is still unclear. Here we report of a physical and functional interaction between High Mobility Group A1 (HMGA1) protein and p53 oncosuppressor. We found that HMGA1 binds p53 in vitro and in vivo, and both proteins are present in the same complexes bound to the Bax gene promoter. HMGA1 interferes with the p53-mediated transcription of p53 effectors Bax and p21(waf1) while cooperates with p53 in the transcriptional activation of the p53 inhibitor mdm2. This transcriptional modulation is associated with a reduced p53-dependent apoptosis in cells expressing exogenous HMGA1 and p53, or in cells expressing endogenously the proteins and in which p53 was activated by UV-irradiation. Furthermore, antisense inhibition of HMGA1b expression dramatically increases the UV-induced p53-mediated apoptosis. These data define a new physical and functional interaction between HMGA1 and p53 that modulates transcription of p53 target genes and inhibits apoptosis.
authors.affiliation: Dipartimento di Biologia e Patologia Cellulare e Molecolare, Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli Federico II, via S. Pansini 5, 80131 Naples, Italy.
authors.forename: G M
authors.initials: GM
authors.lastname: Pierantoni
authors.forename: C
authors.initials: C
authors.lastname: Rinaldo
authors.forename: F
authors.initials: F
authors.lastname: Esposito
authors.forename: M
authors.initials: M
authors.lastname: Mottolese
authors.forename: S
authors.initials: S
authors.lastname: Soddu
authors.forename: A
authors.initials: A
authors.lastname: Fusco
mesh_terms: D017209:Apoptosis; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D025742:HMGA1b Protein / Q000378:metabolism*; D006801:Humans; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014466:Ultraviolet Rays; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D025742:HMGA1b Protein; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2