Project description:The p53-family of transcription factors share a highly homologous DNA binding domain and have overlapping and distinct biological functions. Using chromatin immunoprecipitation in combination with NimbleGen promoter arrays and a Model-based Algorithm for Promoter arrays (MAP), we performed a direct comparison of the promoter occupancy profiles of p53 and p73 before and after treatment with hydroxyurea (HU). We have found that p53 and p73 bind to common promoters before HU treatment. After HU treatment, we found that p53-bound promoters are likely to also bind p73, but p73 binds to additional promoters that that do not bind p53. Among them, we showed that p73 but not p53 is recruited to the promoter of MLH3, which encodes a mismatch repair protein. The differential effects of HU on the promoter occupancy profiles of p53 and p73 suggest that these related transcription factors have divergent functions in DNA damage response. The main goal of this study is to examine the effect of HU on the promoter occupancy profiles of p53 and p73. One biological sample from HCT116-(6) cells treated with or without Hydroxyurea was subjected to ChIP-chip analysis using a model based algorithm for promoter arrays (MAP).
Project description:The main goal of this study is to integrate gene expression analysis with ChIP-chip study. To examine the relationship between promoter occupancy and gene expression, we transiently depleted p53 and p73 via small interfering RNA (siRNA) in HCT116-3(6) cells and then performed microarray analysis of 32,000 genes before or after HU treatment using the Phalanx expression array platform. We found that only 6%-14% of p53 and p73 bound promoters at FDRMAP <0.05 exhibited significant changes in mRNA expression when p53 and p73 were simultaneously knocked-down by siRNA. The minimal correlation between binding and regulation of expression is consistent with previous observations of the lack of transcriptional effects at many transcription factor binding sites.
Project description:p73 is a p53 family transcription factor that plays critical roles during development and tumor suppression. We analyzed p73 activity using a combination of ChIP-on-Chip and gene expression profiling, both at baseline and after treatment with the mTOR inhibitor rapamycin. We generated an mTOR-p73 gene signature that predicts rhabdomyosarcoma tumor subtype and patient outcome, and is enriched for p73 target genes involved in mesenchymal stem cell differentiation and tumorigenesis. Rh30 rhabdomyosarcoma cells were infected with lentivirus (either control or expressing one of two RNAi constructs targeting p73) for 3 d, and treated with vehicle or 40 nM rapamycin for 24 h, and then total RNA was harvested. Experiments were performed in duplicate for a total of 8 samples. For p73 RNAi, a different targeting construct was used for each replicate.
Project description:p73 is a p53 family transcription factor that plays critical roles during development and tumor suppression. We analyzed p73 activity using a combination of ChIP-on-Chip and gene expression profiling, both at baseline and after treatment with the mTOR inhibitor rapamycin. We report the first comprehensive analysis of p73 binding across the genome. Furthermore, we re-analyzed this p73 cistrome after perturbation with rapamycin, an inhibitor of mTOR and inducer of p73. Multiple determinants of p73 binding, activity, and function were evident, and were modulated by mTOR.
Project description:The integral role of p53 in tumor suppression has promted many laboratories to perform extensive analyses of signaling pathways downstream of the p53 family of sequence-specific DNA binding transcription factors (p53 and its homologs p63 and p73). Despite the ability of p73 to regulate many p53 family target genes, little is known about the specific pathways that modulate p73 during development, tumorigenesis and tumor therapy. In this study we present a gene signature-based approach for connecting signaling pathways to transcription factors, as exemplified by p73. We generated a p73 gene signature by integrating whole-genome chromatin immunoprecipitation and expression profiling. Experiment Overall Design: H1299 lung carcinoma cells were transduced with TAp73beta or GFP expressing adenoviruses. Microarray analysis (on the GFP and TAp73beta samples) and ChIPSeq analysis (on the TAp73beta sample) were performed to identify candidate p73 target genes.
Project description:We performed p53 ChIP-seq analysis of Nutlin-treated HCT116 cells to identify high-confident p53 regulated targets. And we performed ChIP-seq using an anti-p53 antibody in HCT116 cells treated with control or iASPP RNAi to identify iASPP regulated p53 targets.