Reactivation of Gamma Globin Expression in β-Hemoglobinopathies

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ABSTRACT Oxygen delivery to the body’s tissues and organs is dependent on the qualitative and quantitative features of hemoglobin, a tetrameric protein made up of two α- and two β-like subunits. β- hemoglobinopathies are the most common monogenic disorders worldwide, and are defined based on whether patients have quantitative (β-thalassemia) or qualitative (Sickle Cell Disease (SCD)) defects in β- globin synthesis. Unfortunately, there are few treatment options for β-hemoglobinopathies. However, it has been shown that an alternative β-like subunit, γ-globin, has the ability to compensate for the β-globin defect in SCD and β-thalassemia. To date, few potential activators of γ-globin expression have been discovered. Additionally, a recent study showed that steric hindrance at the γ-globin promoter (~150bp upstream of the transcription start site) led to a decrease in γ-globin expression- implying the presence of a γ-globin activator-binding region. Consistent with these findings, I have performed a pooled genome- wide CRISPR activation screen that identified several novel candidate genes that may activate γ-globin expression. In this proposal, I aim to validate these candidate γ-globin activators that I uncovered in my screen and perform studies to determine the mechanism by which these candidate genes increase γ- globin expression. Additionally, in my recent work I have found that a high percentage of slow cycling human erythroid cells express γ-globin (termed F-cells) compared to erythroid cells with normal cycling speeds. In this proposal, I also aim to dissect the impact of cell cycle speed regulation on γ-globin expression. From this work I expect to uncover critical regulators of γ-globin. These newfound regulators may lead to the development of novel therapeutics for β-hemoglobinopathies. Importantly, this proposal will allow me to develop the skills, knowledge, and experience for a successful career in academic research.