Batf defines a differentiation checkpoint limiting hematopoietic stem cell self renewal in response to DNA damage

Abstract

There is growing evidence that the accumulation of DNA damage and telomere dysfunction contributes to declines in stem cell function and tissue maintenance during aging and in response to chronic disease. Checkpoint responses that mediate the decline in stem cell function in response to DNA damage remain yet to be delineated. Here we conducted a functional genomic in vivo screen to identify genes impairing the function of hematopoietic stem cells in the context of chronic DNA damage induced by telomere dysfunction. Screening a shRNA library of 1000 cancer related genes revealed that shRNA mediated knock down of the transcription factor Batf was most potent to rescue the function of telomere dysfunctional stem cells. Specifically, Batf knockdown was 500fold enriched in telomere dysfunctional HSCs compared to wildtype HSCs when transplanted into lethally irradiated recipients. Our study shows that Batf is strongly upregulated in HSCs in response to telomere dysfunction or gamma-irradiation induced DNA damage and during mouse aging. Upregulation of Batf in HSCs in response to DNA damage was G-CSF/Stat3 dependent. shRNA-mediated knockdown of Batf rescued the repopulation capacity of telomere dysfunctional stem cells in transplanted recipients. This rescue in HSC function was associated with impaired induction of lymphocyte differentiation markers, cell cycle inhibitors (p53, p21, p16), and apoptosis in telomere dysfunctional or gamma-irradiated HSCs. Irradiation experiments revealed that lymphoid competent HSCs (CD150lowCD34-KSL) were most sensitive to DNA damage induced stem cell depletion, which was rescued by shRNA mediated knockdown of Batf. Together, this study provides the first experimental evidence that DNA damage leads to induction of a Batf-dependent differentiation checkpoint limiting the repopulation capacity of HSCs and the self-renewal of lymphoid