Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA401837 | ENA |
REPOSITORIES: ENA
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Project description:B-hemoglobinopathies such as Sickle Cell Disease (SCD) and b-thalassemia result from mutations in the adult b-globin gene. Reactivating the developmentally silenced fetal g-globin gene is a therapeutic goal for treating SCD and b-thalassemia1. Some forms of Hereditary Persistence of Fetal Hemoglobin (HPFH), a rare benign condition in which individuals express g‑globin throughout adulthood, are caused by point mutations in the g‑globin gene promoter at regions residing ~115 and 200 base pairs upstream of the transcription start site. Here we show that the major fetal globin repressors BCL11A and ZBTB7A/LRF directly bind to the -115 and ‑200 sites, respectively. Furthermore, introduction of naturally occurring HPFH mutations into erythroid cells by CRISPR/Cas9 disrupts repressor binding and raises g‑globin expression. These findings resolve the mystery surrounding how these HPFH mutations operate and demonstrate that BCL11A and ZBTB7A/LRF are major direct repressors of the fetal globin gene.
2018-01-29 | GSE103445 | GEO
Project description:Genes encoding the human β-like hemoglobin proteins undergo a developmental switch from fetal γ-globin to adult β-globin expression at around the time of birth. β-hemoglobinopathies, such as sickle cell disease and β-thalassemia, result from mutations affecting the adult β-globin gene. The only treatment options currently available carry significant side-effects. Analyses of heritable variations in fetal hemoglobin (HbF) levels have provided evidence that reactivation of the silenced fetal γ-globin genes in adult erythroid cells is a promising therapy. The γ-globin repressor BCL11A has become the major focus with several studies investigating its regulation and function as a first step to inhibiting its expression or activity. However, a second repression mechanism has recently been shown to be mediated by the transcription factor ZBTB7A/LRF, suggesting that understanding the regulation of ZBTB7A may also be useful. Here we show that KLF1 directly drives expression of ZBTB7A in erythroid cells by binding to its proximal promoter. We have also uncovered an erythroid-specific regulation mechanism, leading to the upregulation of a novel ZBTB7A transcript in the erythroid compartment. The demonstration that ZBTB7A, like BCL11A, is a KLF1 target gene also fits with the observation that reduced KLF1 expression or activity is associated with HbF derepression.
2017-04-13 | GSE97671 | GEO
Project description:The fetal-to-adult hemoglobin switch is regulated in a developmental stage-specific manner and reactivation of fetal hemoglobin (HbF) has therapeutic potential for β-hemoglobinopathies. Although BCL11A and ZBTB7A interact with their coregulators, reportedly mediating most γ-globin transcriptional silencing in erythroid in trans, and in cis, the molecular mechanism underlying the epigenetic dysregulation of the switch remains largely unclear. Here we showed that epigenetic inactivation of an ETS2 repressor factor (ERF) reactivates γ-globin expression during stress erythropoiesis, and ERF depletion elevates γ-globin in erythroid cells and in erythroid progenies from the edited HSPCs engrafted into immunodeficient mice. ERF represses γ-globin by directly binding to two motifs regulating HBG expression, independently of the major HbF repressors BCL11A and ZBTB7A. We further uncovered that an lncRNA, RP11-196G18.23 mediates ERF promoter hypermethylation resulting in reactivation of g-globin. Herein, the epigenetic alterations were identified as novel modulators ameliorating the severity of b-thalassemia, thus providing novel therapeutic targets for β-hemoglobinopathies.
2020-12-27 | GSE160602 | GEO
Project description:The fetal-to-adult hemoglobin switch is regulated in a developmental stage-specific manner and reactivation of fetal hemoglobin (HbF) has therapeutic potential for β-hemoglobinopathies. Although BCL11A and ZBTB7A interact with their coregulators, reportedly mediating most γ-globin transcriptional silencing in erythroid in trans, and in cis, the molecular mechanism underlying the epigenetic dysregulation of the switch remains largely unclear. Here we showed that epigenetic inactivation of an ETS2 repressor factor (ERF) reactivates γ-globin expression during stress erythropoiesis, and ERF depletion elevates γ-globin in erythroid cells and in erythroid progenies from the edited HSPCs engrafted into immunodeficient mice. ERF represses γ-globin by directly binding to two motifs regulating HBG expression, independently of the major HbF repressors BCL11A and ZBTB7A. We further uncovered that an lncRNA, RP11-196G18.23 mediates ERF promoter hypermethylation resulting in reactivation of g-globin. Herein, the epigenetic alterations were identified as novel modulators ameliorating the severity of b-thalassemia, thus providing novel therapeutic targets for β-hemoglobinopathies.
2020-12-27 | GSE160601 | GEO
Project description:Hemoglobinopathies, including sickle cell disease and _-thalassemia, are global public health concerns. Induction of fetal-type hemoglobin (HbF) is a promising means to treat these disorders; however, precisely how HbF expression is silenced in adult erythroid cells is not fully understood. Here, we show that the LRF/ZBTB7A transcription factor is a potent repressor of HbF production. LRF inactivation derepresses embryonic/fetal _-globin expression in mouse and human adult erythroid cells. We employed genome-wide analysis of the transcriptome, chromatin accessibility and LRF occupancy sites, and demonstrate that LRF occupies the _-globin loci and maintains nucleosome density necessary for _-globin silencing. LRF confers its repressive activity through a unique NuRD repressor complex independent of BCL11A. Strikingly, human erythroid lines lacking both LRF and BCL11A exhibited almost a complete switch in expression from adult- to fetal-type globin, suggesting that these two factors cumulatively represent the near entirety of _-globin repressive activity in adult erythroid cells. RNA-seq, LRF ChIP-seq and ATAC-seq assays were used to investigtae LRF binding, effect of LRF depletion on transcription and chromatin landscape in mouse and human cells.
2016-01-15 | E-GEOD-74977 | biostudies-arrayexpress
Project description:Hemoglobinopathies, including sickle cell disease and _-thalassemia, are global public health concerns. Induction of fetal-type hemoglobin (HbF) is a promising means to treat these disorders; however, precisely how HbF expression is silenced in adult erythroid cells is not fully understood. Here, we show that the LRF/ZBTB7A transcription factor is a potent repressor of HbF production. LRF inactivation derepresses embryonic/fetal _-globin expression in mouse and human adult erythroid cells. We employed genome-wide analysis of the transcriptome, chromatin accessibility and LRF occupancy sites, and demonstrate that LRF occupies the _-globin loci and maintains nucleosome density necessary for _-globin silencing. LRF confers its repressive activity through a unique NuRD repressor complex independent of BCL11A. Strikingly, human erythroid lines lacking both LRF and BCL11A exhibited almost a complete switch in expression from adult- to fetal-type globin, suggesting that these two factors cumulatively represent the near entirety of _-globin repressive activity in adult erythroid cells.
2016-01-15 | GSE74977 | 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:The benign condition Hereditary Persistence of Foetal Haemoglobin (HPFH) is known to ameliorate symptoms when co-inherited with beta-haemoglobinopathies, such as sickle cell disease and beta-thalassaemia. The condition is sometimes associated with point mutations in the foetal globin promoters that disrupt the binding of the repressors BCL11A or ZBTB7A/LRF, which have been extensively studied. HPFH is also associated with a range of deletions within the beta-globin locus that all reside downstream of the foetal HBG2 gene. These deletional forms of HPFH are poorly understood and are the focus of this study. Numerous different mechanisms have been proposed to explain how downstream deletions can boost the expression of the foetal globin genes, including the deletion of silencer elements, of genes encoding non-coding RNA, and bringing downstream enhancer elements into proximity with the foetal globin gene promoters. Here we systematically analyse the deletions associated with both HPFH and a related condition known as beta-thalassaemia and propose a unifying mechanism. In all cases where foetal globin is up-regulated, the proximal adult beta-globin (HBB) promoter is deleted. We use CRISPR gene editing to delete or disrupt elements within the promoter and find that virtually all mutations that reduce promoter activity, result in elevated foetal globin expression. These results fit with previous models where the foetal and adult globin genes compete for the distal Locus Control Region and suggest that targeting the promoter might be explored to elevate foetal globin and reduce sickle globin expression as a treatment for beta-haemoglobinopathies.
2022-01-20 | GSE194064 | GEO
Project description:The switch from fetal to adult hemoglobin production has been studied in great depth in part because of its relevance to the treatment of hemolobinopathies. Transcription factor BCL11A, which is essential for repression of the fetal beta-type globin (γ-globin) genes after birth, is largely controlled at the level of transcription but the mechanism of BCL11A developmental control is unknown. Here, using a CRISPR-Cas9 screen in human erythroblasts, we identify transcription factor HIC2 as a repressor of BCL11A transcription. HIC2 and BCL11A expression are anti-correlated in fetal and adult erythroblasts. Forced expression of HIC2 in adult erythroblasts silences BCL11A transcription and markedly induces γ-globin expression. HIC2 binds selectively to constituent erythroid developmental BCL11A enhancer to reduce chromatin accessibility and impair access by transcription factor GATA1, resulting in loss of enhancer activity and enhancer-promoter contacts. Conversely, loss of HIC2 in fetal erythroblasts increases enhancer accessibility, enables GATA1 binding and induces BCL11A transcription. HIC2 is unveiled as a critical evolutionarily conserved regulator of globin gene switching by imposing developmental control on the BCL11A gene.
2022-05-26 | GSE173586 | GEO
Project description:The switch from fetal to adult hemoglobin production has been studied in great depth in part because of its relevance to the treatment of hemolobinopathies. Transcription factor BCL11A, which is essential for repression of the fetal beta-type globin (γ-globin) genes after birth, is largely controlled at the level of transcription but the mechanism of BCL11A developmental control is unknown. Here, using a CRISPR-Cas9 screen in human erythroblasts, we identify transcription factor HIC2 as a repressor of BCL11A transcription. HIC2 and BCL11A expression are anti-correlated in fetal and adult erythroblasts. Forced expression of HIC2 in adult erythroblasts silences BCL11A transcription and markedly induces γ-globin expression. HIC2 binds selectively to constituent erythroid developmental BCL11A enhancer to reduce chromatin accessibility and impair access by transcription factor GATA1, resulting in loss of enhancer activity and enhancer-promoter contacts. Conversely, loss of HIC2 in fetal erythroblasts increases enhancer accessibility, enables GATA1 binding and induces BCL11A transcription. HIC2 is unveiled as a critical evolutionarily conserved regulator of globin gene switching by imposing developmental control on the BCL11A gene.
2022-05-26 | GSE173584 | GEO