Ionizing radiation (IR) has long been associated with reduced hematopoietic function and increased malignancies, although the mechanisms behind this relationship remain poorly understood. The carcinogenic effect of IR has been commonly attributed to the direct induction of DNA damage. We demonstrate that IR exposure results in long-term, somatically heritable, cell-intrinsic reductions in HSC self-renewal that is mediated by C/EBP and reversed by Notch, both of which are associated with human leukemias. Remarkably, restoration of HSC self-renewal prevents selection for C/EBP loss of function in previously irradiated HSC pools. We propose that environmental insults prompt HSC to initiate a program limiting their self-renewal to prevent damaged HSC from contributing to hematopoiesis. This "programmed mediocrity" is advantageous for the localized insults animals have evolved to deal with, but becomes tumor promoting when the entire HSC compartment is damaged, such as during total body irradiation, by increasing selective pressure for adaptive oncogenic mutations SOURCE: Jihye Kim (Jihye.Kim@UCDenver.edu) - Tan UCDenver

Pluto Bioinformatics

GSE61602: Opposing Roles for C/EBP and Notch in Irradiation-induced Hematopoietic Stem Cell Defects