HRI activates ATF4 to promote BCL11A transcription and fetal hemoglobin silencing
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ABSTRACT:
PROVIDER: PRJNA602341 | ENA |
REPOSITORIES: ENA
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Project description:Through a CRISPR-Cas9 guided loss-of-function screen in human erythroid cells we identified transcription factor ATF4, a known HRI-regulated protein, as a novel γ-globin repressor. ATF4 binds to a BCL11A enhancer to augment promoter contacts, stimulates BCL11A transcription to repress γ-globin expression. Notably, mice deficient for HRI displayed normal Bcl11a levels, suggesting species selective regulation that we explain here by demonstrating that the analogous ATF4 motif at the murine Bcl11a enhancer is largely dispensable. This illustrates potential limits of commonly used murine models of globin gene regulation.
2020-04-17 | GSE143962 | GEO
Project description:Through a CRISPR-Cas9 guided loss-of-function screen in human erythroid cells we identified transcription factor ATF4, a known HRI-regulated protein, as a novel γ-globin repressor. ATF4 binds to a BCL11A enhancer to augment promoter contacts, stimulates BCL11A transcription to repress γ-globin expression. Notably, mice deficient for HRI displayed normal Bcl11a levels, suggesting species selective regulation that we explain here by demonstrating that the analogous ATF4 motif at the murine Bcl11a enhancer is largely dispensable. This illustrates potential limits of commonly used murine models of globin gene regulation.
2020-04-17 | GSE143961 | GEO
Project description:HRI activates ATF4 to promote BCL11A transcription and fetal hemoglobin silencing [Capture-C]
| PRJNA602343 | ENA
Project description:HRI activates ATF4 to promote BCL11A transcription and fetal hemoglobin silencing [ChIP-seq]
| PRJNA602344 | ENA
Project description:Increasing fetal hemoglobin (HbF) provides clinical benefit in patients with sickle cell disease (SCD). We recently identified heme-regulated inhibitor (HRI, EIF2AK1) as a novel HbF regulator. Since HRI is an erythroid-specific protein kinase it presents a potential target for pharmacologic intervention. We find that maximal HbF induction requires >80-85% HRI depletion. As it remains unclear whether this degree of HRI inhibition can be achieved pharmacologically, we explored whether HRI knockdown can be combined with pharmacologic HbF inducers to achieve greater HbF production and minimize potential adverse effects associated with treatments. Strongly cooperative HbF induction was observed when HRI depletion was combined with exposure to pomalidomide or the EHMT1/2 inhibitor UNC0638, but not hydroxyurea. Mechanistically, reduction in the levels of the HbF repressor BCL11A reflected the cooperativity of HRI loss and pomalidomide treatment, whereas UNC0638 did not modulate BCL11A levels. In conjunction with HRI loss, pomalidomide maintained its HbF inducing activity at 10-fold lower concentrations, at which condition there were minimal observed detrimental effects on erythroid cell maturation and viability as well as fewer alterations in the erythroid transcriptome. In sum, this study provides a foundation for the exploration of combining future small molecule HRI inhibitors with additional pharmacologic HbF inducers to maximize HbF production and preserve erythroid cell functionality for the treatment of SCD and other hemoglobinopathies.
2020-09-21 | GSE150341 | GEO
Project description:Increasing fetal hemoglobin (HbF) levels in adult red blood cells provides clinical benefit to patients with sickle cell disease and some forms of beta-thalassemia. To identify potentially druggable HbF regulators in adult human erythroid cells, we employed a protein kinase-domain focused CRISPR/Cas9-based genetic screen with a newly optimized sgRNA scaffold. The screen uncovered the heme-regulated inhibitor HRI (also known as EIF2AK1), an erythroid-specific kinase that controls protein translation, as an HbF repressor. HRI depletion markedly increased HbF production in a specific manner and reduced sickling in cultured erythroid cells. Diminished expression of the HbF repressor BCL11A accounted in large part for the effects of HRI depletion. Taken together, these results suggest HRI as a potential therapeutic target for hemoglobinopathies.
2018-07-20 | GSE115687 | GEO
Project description: Not available
| S-EPMC7290097 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2020-04-17 | GSE143963 | GEO
Project description:Fetal hemoglobin (HbF) level is genetically controlled and modifies severity of adult hemoglobin (HbA) disorders. Common genetic variation affects expression of BCL11A, a critical regulator of HbF silencing. Current models suggest that BCL11A acts at a distance from the gamma-globin genes via long-distance chromosomal interactions. Here we use a functional cellular assay and protein-binding microarray to establish a requirement for a zinc-finger cluster of BCL11A for globin repression, and identify a preferred DNA recognition sequence (TGACCA). The motif is present in embryonic and fetal-expressed globin promoters, and duplicated in gamma-globin promoters, yet only the distal motif is mutated in alleles of individuals with hereditary persistence of hemoglobin. Using CUT&RUN to map protein binding sites, we detected BCL11A occupancy preferentially at the distal motif, and validated its absence in HbF-expressing, promoter-edited erythroid cells. Taken together, our findings reveal that direct gamma-globin gene promoter repression by BCL11A underlies hemoglobin switching.
2018-03-30 | GSE104676 | GEO
Project description:Basak A, Munschauer M, Lareau CA, Montbleau KE, Ulirsch JC, Hartigan CR, Schenone M, Lian J, Wang Y, Huang Y, Wu X, Gehrke L, Rice CM, An X, Christou HA, Mohandas N, Carr SA, Orkin SH, Chen JJ, Lander ES, and Sankaran VG.
Increased production of the beta-like gamma-globin genes that form fetal hemoglobin can ameliorate the severity of sickle cell disease and beta-thalassemia, the major hemoglobin disorders. BCL11A is a key repressor of the gamma-globin genes and is expressed in a developmental stage-specific manner to regulate the physiologic fetal-to-adult hemoglobin switch. Despite extensive studies, the upstream mechanisms underlying the developmental expression of BCL11A and hemoglobin switching in humans have remained mysterious. Here we show that BCL11A is regulated at the level of mRNA translation during human hematopoietic development. While BCL11A mRNA is comparably expressed at all developmental stages in erythroid cells, robust protein expression only occurs in adult erythroid cells. Importantly, at the earlier stages of development, the observed reduction in protein expression is attributable to decreased synthesis and not increased degradation of BCL11A. While BCL11A protein is not well synthesized at these earlier stages of development, its mRNA curiously continues to be associated with ribosomes. Through unbiased proteomic analyses in erythroid cells, we demonstrate that the RNA-binding protein LIN28B, which is developmentally expressed in a reciprocal pattern to BCL11A, directly interacts with ribosomes. We show that the observed suppression of BCL11A protein translation is mediated by LIN28B through a direct interaction with BCL11A mRNA and independent of its role in let-7 microRNA biogenesis. Finally, we show that BCL11A is the major functional target in LIN28B-mediated fetal hemoglobin induction. Our results reveal a previously unappreciated regulatory mechanism underlying human hemoglobin switching and illuminate opportunities for developing improved treatments for sickle cell disease and beta-thalassemia.
2019-10-09 | MSV000084443 | MassIVE