Cell context dependent p53 genome-wide binding patterns and enrichment at repeats

Area of Science:

• Molecular Biology
• Genomics
• Cancer Research

Background:

• The tumor suppressor protein p53 plays a critical role in cellular responses to stress.
• The precise mechanisms governing p53's cell type and stress-specific genomic interactions are not fully understood.
• It remains unclear if p53 binding to DNA targets varies depending on the cellular context.

Purpose of the Study:

• To investigate whether p53 exhibits cell context-dependent binding to the human genome.
• To compare the genome-wide binding patterns of p53 in a human cancer cell line (HCT116) and a normal cell line (IMR90).

Main Methods:

• Chromatin immunoprecipitation sequencing (ChIP-seq) was employed to map endogenous wild-type p53 binding sites.
• Genomic binding sites were analyzed in HCT116 (cancer, epithelial) and IMR90 (normal, mesenchymal) cell lines under identical experimental conditions.
• p53 binding site distribution was correlated with genomic and epigenomic features, including repeat elements.

Main Results:

• Distinct p53 genome-wide binding landscapes were observed between HCT116 and IMR90 cells.
• Differences in p53 binding were noted with respect to promoter regions, CpG islands, and repeat elements.
• p53 binding was significantly enriched at LINE repeats in HCT116 cells compared to IMR90 cells.
• These variations likely reflect differences in epigenetic landscapes influenced by cancer-associated changes and cell lineage.

Conclusions:

• p53 binding to the human genome is selective and highly dependent on the cellular context.
• The distinct binding patterns suggest p53 mobilizes different sets of genes and pathways in different cell types.
• This selectivity contributes to the diverse roles of p53 in cellular responses and disease.