The Transcriptional Repressor hDaxx Potentiates p53-dependent Apoptosis

Abstract

p53 and its homologues p73 and p63 are transcription factors that play an essential role in modulating cell cycle arrest and cell death in response to several environmental stresses. The type and intensity of these responses, which can be different depending on the inducing stimulus and on the overall cellular context, are believed to rely on the activation of defined subsets of target genes. The proper activation of p53 family members requires the coordinated action of post-translational modifications and interaction with several cofactors. In this study, we demonstrate that the multifunctional protein hDaxx interacts with p53 and its homologues, both in vitro and in vivo, and modulates their transcriptional activity. Moreover, we show that hDaxx, which has been implicated in several apoptotic pathways, increases the sensitivity to DNA damage-induced cell death and that this effect requires the presence of p53. Although hDaxx represses p53-dependent transcription of the p21 gene, it does not affect the activation of proapoptotic genes, and therefore acts by influencing the balance between cell cycle arrest and proapoptotic p53 targets. Our results therefore underline the central role of hDaxx in modulating the apoptotic threshold upon several stimuli and identify it as a possible integrating factor that coordinates the response of p53 family members.

Peptide Aptamers Targeting Mutant p53 Induce Apoptosis in Tumor Cells

“…Coimmunoprecipitation (Co-IP) and in vitro binding assays were performed as described in Supplementary Data and as previously described (26). Western Blot analysis was performed using affinity purified polyclonal anti-green fluorescent protein (GFP); monoclonal anti-p53 antibody (clone: DO1; S.Cruz Biotechnology), monoclonal anti-HA (SIGMA), monoclonal anti-vesicular stomatitis virus (VSV; SIGMA), anti-PARP p85 polyclonal antibody (Promega), anti-Bax polyclonal antibody (Cell Signaling), and antiactin polyclonal antibody (SIGMA).…”

MAGE-A tumor antigens target p53 transactivation function through histone deacetylase recruitment and confer resistance to chemotherapeutic agents

“…Retroviral infection was performed through standard protocol by using pSuperRetro (pSR) vector (OligoEngine) encoding a sequence (5Ј-AACCAGCTATGTGAAAGTC-3Ј) (pSRMage) with 100% matching to several MAGE-A genes (A1, A2, A3, A4, A6, A7, A8, and A12) followed by puromycin selection. p53 activity was controlled by using pBabe-EGFP-TNVp53OD (24) followed by hygromycin selection.…”

HMGA1 Inhibits the Function of p53 Family Members in Thyroid Cancer Cells

“…pWWP (containing the p53-responsive element of the p21 promoter), pWP124 (devoid of the p53-responsive element), and PGVB2 luciferase plasmids were kindly donated by Prof. T. Sakai (Kyoto Prefectural University of Medicine, Kyoto, Japan). pcDNA-HATNV 322-355, pcDNA-HATNV 355-363, and pcDNA-HATNV 363-384 containing oligonucleotides encoding p53 peptides cloned within the Escherichia coli thioredoxin cDNA have been described elsewhere (40).…”