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Editing the core region in HPFH deletions alters fetal and adult globin expression for treatment of β-hemoglobinopathies [4C]

ABSTRACT: We have identified putative repressor region (PRR) to exon-1 of β-globin (βE1) in the β-globin cluster as a core region in alll the HPFH deletions that activates fetal hemoglobin and silences adult hemoglobin. To test the impact of PRR-βE1 gene editing in β-globin cluster configuration, we employed Circular chromosome conformation capture (4C) analysis to assess the LCR interaction to the gamma-globin promoter. Using HBG2 promoter as viewpoint,4C analysis showed an increased interaction of HBG promoter to the hypersensitive (HS) sites of the LCR in HUDEP-2 clones harbouring PRR-βE1 biallelic deletions compared to control HUDEP-2 cells. Link for 4C output files Mendeley - Venkatesan, Vigneshwaran (2022), “4C data set ”, Mendeley Data, V1, doi: 10.17632/cz3thnr9kf.1

ORGANISM(S): Homo sapiens

PROVIDER: GSE201388 | GEO | 2022/04/26

REPOSITORIES: GEO

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Editing the core region in HPFH deletions alters fetal and adult globin expression for treatment of β-hemoglobinopathies

Project description:We have identified putative repressor region (PRR) to exon-1 of β-globin (βE1) in the β-globin cluster as a core region in alll the HPFH deletions that activates fetal hemoglobin and silences adult hemoglobin. Here we charactised the transcriptome of the erythroblasts derived from PRR-βE1 gene edited HSPCs. Transcriptome analysis showed an increased expression of HBG, HBBP1 and decreased expression of HBB transcripts compared to control.

2022-04-25 | GSE201346 | GEO

Epigenetic modifications and chromosome conformations of the beta globin locus throughout development

Project description:Human embryonic stem cells provide an alternative to using human embryos for studying developmentally regulated gene expression. The co-expression of high levels of embryonic epsilon and fetal gamma globin by the hESC-derived erythroblasts allows the interrogation of epsilon globin regulation at the transcriptional and epigenetic level which could only be attained previously by studying cell lines or transgenic mice. In this study, we compared the histone modifications across the beta globin locus of the undifferentiated hESCs and hESC-, FL-, and mobilized PB CD34+ cells-derived erythroblasts, which have distinct globin expression patterns corresponding to their developmental stages. We demonstrated that the histone codes employed by the beta globin locus are conserved throughout development. Furthermore, in spite of the close proximity of the epsilon globin promoter, as compared to the gamma or beta globin promoter, with the LCR, a chromatin loop was also formed between the LCR and the active epsilon globin promoter, similar to the loop that forms between the gamma or beta globin promoters and the LCR, in contrary to the previously proposed tracking mechanism. Human embryonic stem cells, hESC-, FL-, and PB derived erythroblasts were studied. The enrichment of H3K4me3 and AcH3 acrossed the beta globin locus was studied using ChIP-seq.

2015-01-26 | E-GEOD-35375 | biostudies-arrayexpress

Disrupting the adult-globin promoter alleviates promoter competition and reactivates foetal-globin gene expression

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

Epigenetic modifications and chromosome conformations of the beta globin locus throughout development

2015-01-26 | GSE35375 | GEO

Micro-Capture-C to determine the long-range interaction of HBG1/2 promoter with the locus control region (LCR), a powerful upstream enhancer in -175 A>G mutantant HUDEP-2 cells.

Project description:Naturally occurring mutations in the γ-globin promoters can result in hereditary persistence of fetal hemoglobin (HPFH), a benign condition that ameliorates the severity of β-hemoglobinopathies through increased post-natal fetal hemoglobin (HbF) expression. Base editing to recreate the HPFH mutations is a promising approach to induce HbF. Compared with Cas9-generated indels, base-editing approaches were more potent, with the −175 A>G conversion resulting in the strongest induction of HbF by creating a new TAL1 binding motif that stimulates long-range interaction with the locus control region (LCR), a powerful upstream enhancer. Micro-Capture-C analysis showed that introducing the −175 A>G variant stimulated long-range interaction between the γ-globin promoters and the LCR in erythroid progenitor cell line. Together, these findings show that the −175 A>G variant creates a bipartite GATA–TAL1 motif, resulting in the assembly of a GATA1/TAL1/LMO2/LDB1 complex, which activates γ-globin gene transcription by enhancing its physical association with the LCR.

2023-04-28 | GSE228570 | GEO

SOX6 interacting proteins' identification in K562 cells for the regulation of γ-globin gene expression research

Project description:Human fetal γ-globin gene is developmentally silenced around the birth, and reactivation of γ-globin gene in adulthood sheds new light on ameliorating symptoms of hemoglobin disorders, such as sickle cell disease (SCD) and β-thalassemias. However, the precise regulation process of γ-globin remains incompletely understood. Here, we found that a new protein directly interacted with SOX6 and exerted a significant repression effect on the expression of γ-globin gene in erythroid cells. Further studies have demonstrated that it bound directly to γ-globin gene promoter via octamer binding motif, which in turn suppressed the transcriptional activity of γ-globin gene promoter. Thus, these data indicate that this new protein acts as a novel transcriptional repressor in the regulation of γ-globin gene expression through direct promoter binding, implying a potential alternative therapeutic target for the treatment of SCD and β-thalassemias.

2022-02-16 | PXD024259 | Pride

Distinct Ldb1/NLI complexes orchestrate γ-globin repression and re-activation through ETO2 in human adult erythroid cells.

Project description:The Ldb1/GATA-1/TAL1/LMO2 complex mediates long range interaction between the β-globin locus control region (LCR) and gene in adult mouse erythroid cells but whether this complex mediates chromatin interactions at other developmental stages or in human cells is unknown. We investigated human NLI (Ldb1 homologue) complex occupancy and chromatin conformation of the β-globin locus in human erythroid cells. In addition to the LCR, we find robust NLI complex occupancy at a site downstream of the Aγ-globin gene, within sequences of BGL3, an intergenic RNA transcript. In cells primarily transcribing β-globin, BGL3 is not transcribed and BGL3 sequences are occupied by NLI core complex members together with co-repressor ETO2 and γ-globin repressor BCL11A. The LCR and β-globin gene establish proximity in these cells. In contrast, when γ-globin transcription is re-activated by cytokines in these cells, ETO2 participation in the NLI complex at BGL3 is diminished, as is BCL11A occupancy, and both BGL3 and γ-globin are transcribed. In these cells, proximity between the BGL3/γ-globin region and the LCR is established. Thus, alternative NLI complexes mediate γ-globin transcription or silencing through long range LCR interactions involving an intergenic site of non-coding RNA transcription and ETO2 is critical to this process. ChIP-chip of GATA-1, NLI, and pol II in cell lines Comparison of GATA-1, NLI, and pol II binding on chromatin. 2 replicates for each protein; ChIP and input DNA for each replicate

2012-01-05 | E-GEOD-30047 | biostudies-arrayexpress

The pivotal and universal role of BGLT3 lncRNA in fetal globin gene expression

Project description:A highly selective and non-genotoxic G9a inhibitor, RK-701 was discovered, which upregulated the mRNA level of γ-globin but not β-globin both in human erythroid cells and in mice. Using RK-701, we examined the induction of the fetal (γ-) globin protein in human erythroid cells; HUDEP-2 and human CD34+ bone marrow and peripheral blood cells.

2023-03-11 | PXD033536 | Pride

Role of LDB1 in the transition from chromatin looping to transcription activation

Project description:Many questions remain about how close association of genes and distant enhancers occurs and how this is linked to transcription activation. In erythroid cells, LDB1 is recruited to the β-globin locus via LMO2 and is required for looping of the β-globin locus control region (LCR) to the active β-globin promoter. We show that the LDB1 dimerization domain (DD) is necessary and, when fused to LMO2 is sufficient, to completely restore LCR-promoter looping and transcription in LDB1 depleted cells. The looping function of the DD is unique and irreplaceable by heterologous dimerization domains. Dissection of the DD revealed distinct functional properties of conserved subdomains. Notably, a conserved helical region (DD4/5) is dispensable for LDB1 dimerization and chromatin looping but essential for transcriptional activation. DD4/5 is required for the recruitment of the co-regulators FOG1 and NuRD complex. Lack of DD4/5 alters histone acetylation and RNA polymerase II recruitment and results in failure of the locus to migrate to the nuclear interior as normally occurs during erythroid maturation. These results uncouple enhancer-promoter looping from nuclear migration and transcription activation and reveal new roles for LDB1in these processes. RNA-seq in LDB1 knockdown, LDB1 delta4/5 construct, LDB1 full-length construct, and control in induced MEL cells; three replicates each.

2014-07-02 | E-GEOD-54549 | biostudies-arrayexpress

Variegated gene expression caused by cell-specific long-range DNA interactions

Project description:Mammalian genomes contain numerous DNA elements with potential transcription regulatory function but unknown target genes. We used transgenic, gain-of-function mice with an ectopic copy of the beta-globin locus control region (LCR) to better understand how regulatory elements dynamically search the genome for target genes. We find that the LCR samples a restricted nuclear sub-volume in which it forms preferential contacts with genes controlled by shared transcription factors. One contacted gene, betah1, located on another chromosome, is upregulated, providing genetic demonstration that mammalian enhancers can function between chromosomes. Upregulation is not pan-cellular but confined to selected ‘jackpot’ cells significantly enriched for inter-chromosomal LCR-betah1 interactions. This implies that long-range DNA contacts are relatively stable and cell-specific and, when functional, cause variegated expression. We refer to this as spatial effect variegation (SEV). The data provide a dynamic and mechanistic framework for enhancer action, important for assigning function to the one- and three-dimensional structure of DNA. A knock-in mouse strain was compared to a wild-type FVB strain. The knock-in mouse strain carries a human beta-globin LCR in the Rad23a locus. We performed 4C for the Rad23a locus in the knock-in and the wild-type strain. Biological replicates were analyzed in a reversed dye orientation. At the RNA level these mice were characterized with Affymetrix expression arrays. We analyzed three biological replicates for the WT and the knock-in.

2011-06-15 | E-GEOD-24614 | biostudies-arrayexpress

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