Hematopoietic stem cells (HSCs) exist in a dormant state, and progressively lose regenerative potency as they undergo successive divisions. Why this functional decline occurs and how this information is encoded is unclear. To better understand how this information is stored, we performed RNA sequencing on HSC populations differing only in their divisional history. Comparative analysis revealed that genes upregulated with divisions are enriched for lineage commitment factors, and are regulated by cell cycle-associated transcription factors, indicating that proliferation itself drives primitive hematopoietic lineage priming. In contrast, downregulated genes are associated with an HSC signature and are targeted by the Polycomb Repressive Complex 2 (PRC2). We find that Ezh2 targets HSC signature genes for repression, and a divisional history-dependent switch from Ezh1 to Ezh2 underlies HSC decline with progressive divisions. Thus cell divisions drive lineage priming and Ezh2 accumulation, which represses HSC signature genes and consolidates information on divisional history into memory. SOURCE: Kateri Moore (kateri.moore@mssm.edu) -  Icahn School of Medicine at Mount Sinai

Pluto Bioinformatics

GSE145772: Memory of cell divisions directs the continuous process of primitive hematopoietic lineage commitment