Role of a Specific P53 Binding Site in Limiting Tissue Overgrowth

Abstract

The p53 protein is an important transcription factor known for maintaining tissue homeostasis by activating genes that have antiproliferative function, such as pro-apoptotic and cytostatic genes. Transcriptional activation of proapoptotic genes has displayed a fundamental role in mediating apoptosis during Drosophila development. Using ChIP-Seq and RNA-Seq methods, we have identified p53 binding sites potentially responsible for p53-mediated induction of pro-apoptotic genes following DNA damage. We have since generated fly lines with the p53 binding site deleted by CRISPR-Cas9-mediated genome editing. To study the effects of the p53 binding site knockout (p53BSKO) on tissue homeostasis, wings of the knockout fly line were dissected, mounted, and then compared against WT wings. Results show p53BSKO animals had an increase in wing size compared to that of the WT. FijiWings 2.2 macros software was used to measure wing hair (trichome) densities, which is directly proportional to cell numbers. This analysis showed that p53BSKO led to hyperplasia of the wing as compared to the WT. Our study indicated that this single P53BS is required for ensuring the right number of cells in a given tissue, likely through mediating overproliferation-induced apoptosis.