Modulation of gene expression in U251 glioblastoma cells by binding of mutant p53 to intronic and intergenic sequences
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ABSTRACT: Missense point mutations in the TP53 gene are frequent genetic alterations in human tumor tissue and cell lines derived thereof. Mutant p53 (mutp53) proteins have lost sequence-specific DNA binding, but have retained the ability to interact in a structure-selective manner with non-B DNA and to act as regulators of transcription. To identify functional binding sites of mutp53, we established a small library of genomic sequences bound by p53R273H in U251 human glioblastoma cells using chromatin immunoprecipitation (ChIP). Mutp53 binding to isolated DNA fragments confirmed the specificity of the ChIP. The mutp53 bound DNA sequences are rich in repetitive DNA elements, which are dispersed over non-coding DNA regions. Stable down-regulation of mutp53 expression strongly suggested that mutp53 binding to genomic DNA is functional. We identified the PPARGC1A and FRMD5 genes as p53R273H targets regulated by binding to intronic and intra-genic sequences. We propose a model that attributes the oncogenic functions of mutp53 to its ability to interact with intronic and intergenic non-B DNA sequences and modulate gene transcription via re-organization of chromatin. For the study of the consequences of mutant p53 (R273H) knockdown on gene expression, total RNA from parental U251 glioblastoma cells and UsiA12 clone was prepared from two independent cell culture experiments (biological replicates) and processed for microarray-based profiling of gene expression. UsiA12 clone was derived from the U251 cells transfected with the pSuper-p53 and pCI-neo vectors.
ORGANISM(S): Homo sapiens
SUBMITTER: Genrich Tolstonog
PROVIDER: E-GEOD-13991 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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