Identification of novel γ-globin inducers among all potential erythroid druggable targets

Human gamma-globin is predominantly expressed in fetal liver erythroid cells during gestation from 2 nearly identical genes, HBG1 and HBG2, that are both perinatally silenced. Reactivation of these fetal genes in adult red blood cells can ameliorate many symptoms associated with the inherited beta-globinopathies, sickle cell disease, and Cooley anemia. Although promising genetic strategies to reactivate the gamma-globin genes to treat these diseases have been explored, there are significant barriers to their effective implementation worldwide; alternatively, pharmacological induction of gamma-globin synthesis could readily reach the majority of affected individuals. In this study, we generated a CRISPR knockout library that targeted all erythroid genes for which prospective or actual therapeutic compounds already exist. By probing this library for genes that repress fetal hemoglobin (HbF), we identified several novel, potentially druggable, gamma-globin repressors, including VHL and PTEN. We demonstrate that deletion of VHL induces HbF through activation of the HIF1 alpha pathway and that deletion of PTEN induces HbF through AKT pathway stimulation. Finally, we show that small-molecule inhibitors of PTEN and EZH induce HbF in both healthy and beta-thalassemic human primary erythroid cells.

Automated summary

This study generated a CRISPR knockout library to target erythroid genes and identified novel gamma-globin repressors. Deletion of VHL and PTEN induces HbF synthesis, and small-molecule inhibitors of PTEN and EZH can also induce HbF production.