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Activation of γ-globin gene expression by GATA1 and NF-Y in hereditary persistence of fetal hemoglobin.

ABSTRACT: Hereditary persistence of fetal hemoglobin (HPFH) ameliorates β-hemoglobinopathies by inhibiting the developmental switch from γ-globin (HBG1/HBG2) to β-globin (HBB) gene expression. Some forms of HPFH are associated with γ-globin promoter variants that either disrupt binding motifs for transcriptional repressors or create new motifs for transcriptional activators. How these variants sustain γ-globin gene expression postnatally remains undefined. We mapped γ-globin promoter sequences functionally in erythroid cells harboring different HPFH variants. Those that disrupt a BCL11A repressor binding element induce γ-globin expression by facilitating the recruitment of nuclear transcription factor Y (NF-Y) to a nearby proximal CCAAT box and GATA1 to an upstream motif. The proximal CCAAT element becomes dispensable for HPFH variants that generate new binding motifs for activators NF-Y or KLF1, but GATA1 recruitment remains essential. Our findings define distinct mechanisms through which transcription factors and their cis-regulatory elements activate γ-globin expression in different forms of HPFH, some of which are being recreated by therapeutic genome editing.

SUBMITTER: Doerfler PA

PROVIDER: S-EPMC8610173 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Activation of γ-globin gene expression by GATA1 and NF-Y in hereditary persistence of fetal hemoglobin

Project description:Naturally occurring mutations in the Î³-globin promoters can result in hereditary persistence of fetal hemoglobin (HPFH), a benign condition that ameliorates the severity of Î²-hemoglobinopathies through increased post-natal fetal hemoglobin (HbF) expression. Mutations in the Î³-globin promoters result in loss or de novo recruitment of transcription factors, yet the cis-regulatory elements involved in Î³-globin transcription in the context of HPFH are not clearly defined. We demonstrate that the -115 cluster of HPFH mutations require GATA1 binding to at -186 in cooperation with NF-Y at the proximal CCAAT box at -85 for Î³-globin expression. We show that multiple HPFH mutations increase HbF in an erythroid cell line and result in GATA1 binding at -186. Mutation of the -186 GATA motif in HPFH erythroid cell lines and erythroid-differentiated CD34+ cells resulted in loss of GATA1 binding and reduction in fetal hemoglobin. NF-Y ChIP-seq in HPFH erythroid cell lines demonstrated binding to the proximal CCAAT box at -85 was also found to be critical for HPFH-mediated Î³-globin expression. Together, the -186 GATA motif and -85 proximal CCAAT box function in an additive and independent manner. Our results reveal detailed evidence for common, positive acting cis-regulatory elements that may provide more general mechanisms for erythroid gene expression.

2021-04-22 | GSE152338 | GEO

Activation of γ-globin gene expression by GATA1 and NF-Y in hereditary persistence of fetal hemoglobin

Project description:Activation of γ-globin gene expression by GATA1 and NF-Y in hereditary persistence of fetal hemoglobin

| PRJNA639052 | ENA

Purification and identification of proteins that bind to the hereditary persistence of fetal hemoglobin -198 mutation in the gamma-globin gene promoter.

Project description:Expression of the gamma-globin gene is silenced in adult humans. However, certain point mutations in the gamma-globin gene promoter are capable of maintaining expression of this gene during adult erythropoiesis, a condition called non-deletion hereditary persistence of fetal hemoglobin (HPFH). Among these, the British form of HPFH carrying a T-->C point mutation at position -198 of the Agamma-globin gene promoter results in 4-10% fetal hemoglobin in heterozygotes. In this study, we used nuclear extracts from murine erythroleukemia cells to purify a protein complex that binds the HPFH -198 gamma-globin gene promoter. Members of this protein complex were identified by mass spectrometry and include DNMT1, the transcriptional coactivator p52, the protein SNEV, and RAP74 (the largest subunit of the general transcription factor IIF). Sp1, which was previously considered responsible for HPFH -198 gamma-globin gene activation, was not identified. The potential role of these proteins in the reactivation and/or maintenance of gamma-globin gene expression in the adult transcriptional environment is discussed.

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Analysis of deletional hereditary persistence of fetal hemoglobin/δβ-thalassemia and δ-globin gene mutations in Southerwestern China.

Project description:BackgroundDeletional hereditary persistence of fetal hemoglobin (HPFH)/δβ-thalassemia and δ-thalassemia are rare inherited disorders which may complicate the diagnosis of β-thalassemia. The aim of this study was to reveal the frequency of these two disorders in Southwestern China.MethodsA total of 33,596 subjects were enrolled for deletional HPFH/δβ-thalassemia, and positive individuals with high fetal hemoglobin (Hb F) level were diagnosed by multiplex ligation-dependent probe amplification (MLPA). A total of 17,834 subjects were analyzed for mutations in the δ-globin gene. Positive samples with low Hb A2 levels were confirmed by δ-globin gene sequencing. Furthermore, the pathogenicity and construction of a selected δ-globin mutation were analyzed.ResultsA total of 92 suspected cases with Hb F ≥5.0% were further characterized by MLPA. Eight different deletional HPFH/δβ-thalassemia were observed at a frequency of 0.024%. In addition, 195 cases suspected to have a δ-globin gene mutation (Hb A2 ≤2.0%) were characterized by molecular analysis. δ-Globin gene mutation was found at a frequency of 0.49% in Yunnan. The pathogenicity and construction for a selected δ-globin mutation was predicted.ConclusionScreening of these two disorders was analyzed in Southwestern China, which could define the molecular basis of these conditions in this population.

| S-EPMC6565566 | biostudies-literature

Genetic variants in the G gamma-globin promoter modulate fetal hemoglobin expression in the Colombian population.

Project description:Fetal hemoglobin (HbF) is a determining factor for the development of sickle cell anemia. High HbF levels lower the intensity of symptoms of this disease. HbF levels can vary in patients with sickle cell anemia and individuals without the disease. The purpose of this study was to identify the genetic variants in the G gamma-globin gene promoter that can modulate HbF expression in patients with sickle cell anemia and healthy individuals from Colombia. In total, 413 bp of the G gamma-globin gene promoter were sequenced in 60 patients with sickle cell anemia and 113 healthy individuals. The allelic and genotype frequencies of the identified variants were compared between individuals with low and high HbF for both patients and healthy individuals. In total, we identified 15 variants in both groups, only three of which were shared between patients and healthy individuals. In healthy individuals, sites -16 and -309 (rs112479156) exhibited differences in allele frequencies. The mutant allele of -16 lowered the production of HbF, whereas the mutant allele of -309 increased its production. These results reveal the presence of different mechanisms of HbF regulation between patients with sickle cell and healthy individuals.

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microRNA expression profiles of reticulocytes for hereditary persistence of fetal hemoglobin and β-thalssemia minor with high fetal hemoglobin.

Project description:We used microarrays to investigate differential microRNA (miRNA) expression in reticulocytes comparing reticulocytes from control individuals with normal fetal hemoglobin (HbF) level to hereditary persistence of fetal hemoglobin (HPFH) and β-thalssemia minor with high HbF, and try to find out some miRNAs associated with the mechanisms of HbF induction.

2018-01-01 | GSE93973 | GEO

Mechanism for fetal hemoglobin induction by histone deacetylase inhibitors involves gamma-globin activation by CREB1 and ATF-2.

Project description:The histone deacetylase inhibitors (HDA-CIs) butyrate and trichostatin A activate gamma-globin expression via a p38 mitogen-activating protein kinase (MAPK)-dependent mechanism. We hypothesized that down-stream effectors of p38 MAPK, namely activating transcription factor-2 (ATF-2) and cyclic AMP response element (CRE) binding protein (CREB), are intimately involved in fetal hemoglobin induction by these agents. In this study, we observed increased ATF-2 and CREB1 phosphorylation mediated by the HDACIs in K562 cells, in conjunction with histone H4 hyperacetylation. Moreover, enhanced DNA-protein interactions occurred in the CRE in the (G)gamma-globin promoter (G-CRE) in vitro after drug treatments; subsequent chromatin immunoprecipitation assay confirmed ATF-2 and CREB1 binding to the G-CRE in vivo. Enforced expression of ATF-2 and CREB produced (G)gamma-promoter trans-activation which was abolished by a 2-base pair mutation in the putative G-CRE. The data presented herein demonstrate that gamma-gene induction by butyrate and trichostatin A involves ATF-2 and CREB1 activation via p38 MAPK signaling.

| S-EPMC1895433 | biostudies-literature

Decitabine increases fetal hemoglobin in Papio anubis by increasing γ-globin gene transcription.

Project description:ObjectiveThe mechanism responsible for increased fetal hemoglobin levels following decitabine treatment remains controversial. These experiments were performed to evaluate the role of transcriptional vs. translational mechanisms in the ability of decitabine to increase fetal hemoglobin levels in vivo.Materials and methodsThree normal, nonanemic baboons were treated with decitabine subcutaneously (0.5 mg/kg/d) for 10 days. The effect of decitabine on globin chain synthesis and globin messenger RNA levels was measured in pre- and posttreatment bone marrow aspirates by biosynthetic radiolabeling with [(3)H] leucine followed by separation of globin chains by high-performance liquid chromatography, and real-time polymerase chain reaction, respectively. The effect on DNA methylation of the ɛ- and γ-globin gene promoters was determined by bisulfite sequence analysis.ResultsDecitabine treatment of normal, nonanemic baboons induced similar increases in the γ/γ+β chain synthetic ratio and the γ/total β-like globin RNA ratio and also increased expression of ɛ-globin transcripts. Increased expression of ɛ- and γ-globin was associated with decreased DNA methylation of the ɛ- and γ-globin gene promoters.ConclusionsDecitabine increases fetal hemoglobin in vivo by transcriptional activation of the γ-globin gene.

| S-EPMC4392404 | biostudies-literature

Haploinsufficiency for the erythroid transcription factor KLF1 causes hereditary persistence of fetal hemoglobin.

Project description:Hereditary persistence of fetal hemoglobin (HPFH) is characterized by persistent high levels of fetal hemoglobin (HbF) in adults. Several contributory factors, both genetic and environmental, have been identified but others remain elusive. HPFH was found in 10 of 27 members from a Maltese family. We used a genome-wide SNP scan followed by linkage analysis to identify a candidate region on chromosome 19p13.12-13. Sequencing revealed a nonsense mutation in the KLF1 gene, p.K288X, which ablated the DNA-binding domain of this key erythroid transcriptional regulator. Only family members with HPFH were heterozygous carriers of this mutation. Expression profiling on primary erythroid progenitors showed that KLF1 target genes were downregulated in samples from individuals with HPFH. Functional assays suggested that, in addition to its established role in regulating adult globin expression, KLF1 is a key activator of the BCL11A gene, which encodes a suppressor of HbF expression. These observations provide a rationale for the effects of KLF1 haploinsufficiency on HbF levels.

| S-EPMC2930131 | biostudies-literature

Correction of murine sickle cell disease using gamma-globin lentiviral vectors to mediate high-level expression of fetal hemoglobin.

Project description:Increased levels of red cell fetal hemogloblin, whether due to hereditary persistence of expression or from induction with hydroxyurea therapy, effectively ameliorate sickle cell disease (SCD). Therefore, we developed erythroid-specific, gamma-globin lentiviral vectors for hematopoietic stem cell (HSC)-targeted gene therapy with the goal of permanently increasing fetal hemoglobin (HbF) production in sickle red cells. We evaluated two different gamma-globin lentiviral vectors for therapeutic efficacy in the BERK sickle cell mouse model. The first vector, V5, contained the gamma-globin gene driven by 3.1 kb of beta-globin regulatory sequences and a 130-bp beta-globin promoter. The second vector, V5m3, was identical except that the gamma-globin 3'-untranslated region (3'-UTR) was replaced with the beta-globin 3'-UTR. Adult erythroid cells have beta-globin mRNA 3'-UTR-binding proteins that enhance beta-globin mRNA stability and we postulated this design might enhance gamma-globin expression. Stem cell gene transfer was efficient and nearly all red cells in transplanted mice expressed human gamma-globin. Both vectors demonstrated efficacy in disease correction, with the V5m3 vector producing a higher level of gamma-globin mRNA which was associated with high-level correction of anemia and secondary organ pathology. These data support the rationale for a gene therapy approach to SCD by permanently enhancing HbF using a gamma-globin lentiviral vector.

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