The impact of the Trp53 allelic state on the response to gamma-irradiation in hematopoietic stem and progenitor cells

We investigated how the Trp53 allelic state influences the response of hematopoietic stem and progenitor cells (HSPCs) to γ-irradiation. We used a transgenic mouse model harboring hematopoietic cell–specific, tamoxifen-inducible Trp53-R245W missense mutations linked to a GFP reporter. In mice with biallelic transgenes, tamoxifen treatment generates three GFP-defined populations: GFP-negative cells (Trp53 wild-type), GFP-low cells (monoallelic Trp53 mutation, due to recombination of only one transgenic allele), and GFP-high cells (biallelic Trp53 mutation). Flow sorting of these populations enables direct comparison of all three allelic states in HSPCs. Using this system, we sought to define the transcriptional responses of HSPCs with different Trp53 genotypes following γ-irradiation. SCL-CreERT; Trp53-fl-R245W-GFP mice were treated with tamoxifen to induce the Trp53 missense mutations. Five weeks later, mice were either treated with 2.5 Gy of gamma-irradiation or left untreated. 12 hours later, bone marrow cells were harvested, stained, and sorted for Lineage-/Sca1+/c-Kit+ (LSK) cells, and further divided into GFP-neg (wt), GFP-low (monoallelic Trp53 mutation) and GFP-high (biallelic Trp53 mutation) populations. RNA was isolated from these cells and subjected to bulk RNA sequencing.