Identification and Characterization of HIPK2 Interacting with p73 and Modulating Functions of the p53 Familyin Vivo

摘要: To study the biological role of p73 alpha, a member p53 tumor suppressor family, we performed yeast two-hybrid screen human cDNA library. Using alpha fragment consisting amino acids 49-636 as bait, found that is functionally associated with homologue mouse and hamster homeodomain-interacting protein kinase 2 (HIPK2). The homologue, also known haHIPK2 or PKM, was used for further characterization interactions between HIPK2 members family. Systematic assays indicated physical interaction oligomerization domains (amino acid regions 345-380 319-360, respectively) region 812-907 haHIPK2. This includes PEST sequence, an Ubc9-binding domain, partial speckle retention sequence identical to residues 846-941 (hHIPK2). confirmed by glutathione S-transferase pull-down in vitro immunoprecipitation vivo. colocalized nuclear bodies, shown confocal microscopy. Overexpression stabilized greatly increased p73- p53-induced transcriptional repression multidrug-resistant collagenase promoters Saos2 cells but had little effect on p53-mediated activation synthetic p53-responsive p21WAF1 promoters. Stable expression U2OS enhanced cisplatin response sub-G(1) G(2)/M populations, it apoptotic adriamycin demonstrated fluorescence-activated cell sorter 4',6-diamidino-2-phenylindole-staining analyses. potentiated inhibition colony formation p53. These results suggest family may determine roles these proteins cycle regulation apoptosis.