Next Generation Sequencing of Wild Type and Gata2; Mx1-Cre Heterozygote HSCs

These alterations closely associate with deregulated DNA damage responses and inflammatory signalling conveyed from Gata2 haploinsufficient HSCs. We also identify functional interplay between Gata2 and Asxl1, a driver of DNA damage and inflammation and, notably, a recurrent secondary mutation found in GATA2 haploinsufficiency disease progression to MDS/AML. shRNA mediated knockdown of Asxl1 in Gata2 haploinsufficient HSPCs led to a differentiation block in committed progenitor formation beyond that in Gata2 haploinsufficient HSPCs.

By analysis of HSCs from young adult compound Gata2/Asxl1 haploinsufficient mice, we discover hyperproliferation of double haploinsufficent HSCs, which are also functionally compromised in transplantation compared to their single haploinsufficient counterparts. Through both Gata2/Asxl1 dependent and unique transcriptional programs, HSCs from young adult compound Gata2/Asxl1 haploinsufficient mice fortify deregulated DNA damage responses and inflammatory signalling in HSCs initiated in Gata2 haploinsufficient mice and establish a broad pre-leukemic program.

Our data reveal how Gata2 haploinsufficiency initially drives deregulation of HSC genome integrity and suggest the mechanisms of how secondary mutations like ASXL1 take advantage of HSC genomic instability to nurture a pre-leukemic state in GATA2 haploinsufficiency syndromes.