The Clonal Hematopoiesis-associated Gene Srcap Plays an Essential Role in Hematopoiesis

Somatic mutations arising in hematopoietic stem cells (HSCs) may provide the latter with a fitness advantage, allowing the mutant HSC to clonally expand. Such mutations have been recurrently identified in the chromatin modifier, SRCAP, in both non-malignant and leukemic clones, suggesting that this gene plays a significant role in hematopoiesis. We generated a conditional Srcap loss of function murine model and determined the consequences of hematopoietic-specific loss of this gene. We show that Srcap is essential for normal fetal liver erythropoiesis and monocytopoiesis. In Srcap deficient fetal livers, the number of phenotypic HSCs is similar to that of controls, but these HSCs exhibit a profound repopulating defect. Likewise, conditional deletion of Srcap during adult hematopoiesis results in a rapid loss of HSCs. Loss of Srcap is associated with evidence of increased DNA damage in HSCs and lineage-restricted progenitors as assessed by y-H2AX expression. Consistent with this finding, we observed strong transcriptional upregulation of the p53 pathway in Srcap deficient erythroid precursors. Collectively our data highlight the importance of Srcap in maintaining HSC function and supporting hematopoietic differentiation and suggests that it plays an essential role in maintaining genomic integrity.