Gene expression data from E14.5 Pogz-WT and Pogz-KO fetal livers.

Fetal and adult β-globin gene expression is tightly regulated during human development. Fetal globin genes are transcriptionally silenced during embryogenesis through the process of hemoglobin switching. Efforts to understand the transcriptional mechanism(s) behind fetal globin silencing have led to novel strategies to derepress fetal globin expression in the adult, which could alleviate symptoms in hereditary b-globin disorders including sickle cell disease (SCD) and β-thalassemia. We identified a novel zinc finger protein, pogo transposable element with zinc finger domain (Pogz), expressed in mouse and human hematopoietic stem and progenitor cells, which represses embryonic b-like globin gene expression in mice. Ablation of Pogz expression in adult hematopoietic cells in vivo results in persistence of embryonic b-like globin expression without significantly affecting erythroid development or mouse survival. Elevated embryonic β-like globin expression correlates with reduced expression of Bcl11a, a known repressor of embryonic β-like globin expression, in Pogz-/- fetal liver cells. Pogz binds to the Bcl11a promoter, and, to erythroid specific intragenic regulatory regions. Importantly, Pogz+/- mice develop normally, but show elevated embryonic b-like globin expression in peripheral blood cells, demonstrating that reducing Pogz levels results in persistence of embryonic b-like globin expression. Finally, knockdown of POGZ in primary human CD34+ hematopoietic stem and progenitor cell derived erythroblasts, reduces BCL11A expression and increases fetal hemoglobin expression. These findings are significant since new therapeutic targets and strategies are needed to treat the increasing global burden of b-globin disorders. Total RNA was isolated from E14.5 Pogz-WT and Pogz-KO fetal livers (N=3 each genotype) and analyzed for differential gene expression using Affymetrix GeneChip Mouse Genome 430 2.0 arrays.