Effect of the Regnase-1/3-Nfkbiz axis on the epigenomic profile in mouse Flt3–CD48–Lin–Sca1+Kit+ (LSK) cells

Regulation of lineage biases in hematopoietic stem and progenitor cells (HSPCs) is pivotal for balanced hematopoietic output. However, little is known about the mechanism behind lineage choice in HSPCs. Here, we show that mRNA decay factors Regnase-1 (Zc3h12a) and Regnase-3 (Zc3h12c) are critical for induction of myeloid lineage priming, restricting lymphoid differentiation in HSPCs. Regnase-1- and Regnase-3-mediated control of mRNA encoding Nfkbiz, a transcriptional and epigenetic regulator, was essential for balancing lymphoid/myeloid lineage output in HSPCs in vivo. Furthermore, single cell-assay for transposase-accessible chromatin sequencing (scATAC-seq) analysis revealed that Regnase-1 and Regnase-3 control the epigenetic landscape on myeloid-related gene loci in hematopoietic stem cells (HSCs) via Nfkbiz. Consistently, an antisense oligonucleotide designed to inhibit Regnase-1- and Regnase-3-mediated Nfkbiz mRNA degradation primed HSCs toward myeloid lineages by enhancing Nfkbiz expression. Collectively, the collaboration between post-transcriptional control and chromatin remodeling by the Regnase-1/Regnase-3-Nfkbiz axis governs lineage priming, instructing HSC lineage specification. Flt3–CD48–LSK cells were isolated by Fluorescence-activated cell sorting (FACS) from CreERT2+Regnase-1fl/flRegnase-3–/–, CreERT2+Regnase-1fl/flRegnase-3–/–Nfkbizfl/fl, CreERT2+Nfkbizfl/fl, or control mice, and analyzed using scATAC-seq.