Drosophila study maps dual role of Xrp1 in DNA damage response and cell competition downstream of p53

A study published in PLOS Genetics (DOI: 10.1371/journal.pgen.1012309) by Chaitali Khan, Nasser M. Rusan, and Nicholas E. Baker reports that the bZip AT-hook transcription factor Xrp1 carries out at least two distinct genome-protective functions in Drosophila.

First, Xrp1 acts as a transcriptional effector of p53, mediating p53-dependent gene expression and DNA damage-induced apoptosis as part of the DNA damage response (DDR). This places Xrp1 directly downstream of the fly's primary tumour-suppressor pathway. Second, the study describes a p53-independent role for Xrp1 in cell competition — a quality-control process by which less-fit cells are eliminated from a tissue by their neighbours. The two functions are separable, suggesting Xrp1 integrates multiple genome-integrity mechanisms.

Because Drosophila p53 biology is considered a tractable model for understanding how the mammalian p53 pathway suppresses tumourigenesis, these findings may inform research into how p53 coordinates apoptosis, cell competition, and genome stability in human cells. The work is of primary relevance to basic research in cancer biology, developmental genetics, and model-organism genomics.