HEXIM1 Is Essential for the Establishment of Appropriate Patterns of Gene Expression and Chromatin Architecture during Terminal Erythroid Maturation

Terminal erythroid maturation is associated with dramatic changes in gene expression in the setting of a cell that is undergoing rapid division and nuclear condensation. Disruption of this process is associated with inherited anemias and myelodysplastic syndromes. Recent work from our laboratory revealed that terminal erythroid maturation is associated with a dramatic decline in the level of total and elongation competent RNA polymerase II (Pol II), and that control of pol II activity is a critical step in the regulation of gene expression during terminal erythroid maturation. We further demonstrated that HEXIM1, which is highly expressed in early erythroid cells compared to most other cell types (biogps.org; bloodspot.eu), is essential for erythropoiesis (Murphy Blood 2021). The goal of our current study is to understand the mechanisms by which HEXIM1 regulates erythroid gene expression.