Gene expression analysis of human sickle cell disease (SCD) and healthy donor (HD) CD34+ hematopoietic stem/progenitor cells (HSPCs) treated with CRISPR/Cas9 targeting the HBG promoters or untreated samples
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE248671 | GEO | 2024/07/29
REPOSITORIES: GEO
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Project description:Beta-hemoglobinopathies caused by mutations in adult-expressed HBB can be treated by re-activating the adjacent paralogous genes HBG1 and HBG2 (HBG), which are normally silenced perinatally. Although HBG expression is induced by global demethylating drugs, their mechanism is poorly understood and toxicity limits their use. We identified the DNMT1-associated maintenance methylation protein UHRF1 as a mediator of HBG repression in a genome-wide screen. Loss of UHRF1 in the adult-type erythroid cell line HUDEP2 caused global demethylation and HBG activation that was reversed upon localized promoter re-methylation. Conversely, targeted demethylation of the HBG promoters activated their genes in HUDEP2 or primary CD34+ cell-derived erythroblasts. Mutation of MBD2, a CpG-methylation reading component of the NuRD complex, to impair methylation sensitivity recapitulated the effects of promoter demethylation. Our studies demonstrate that localized CpG-methylation at the HBG promoters facilitates developmental silencing and identify a targeted therapeutic approach for b-hemoglobinopathies via epigenomic editing.
2025-06-24 | GSE284289 | GEO
Project description:Beta-hemoglobinopathies caused by mutations in adult-expressed HBB can be treated by re-activating the adjacent paralogous genes HBG1 and HBG2 (HBG), which are normally silenced perinatally. Although HBG expression is induced by global demethylating drugs, their mechanism is poorly understood and toxicity limits their use. We identified the DNMT1-associated maintenance methylation protein UHRF1 as a mediator of HBG repression in a genome-wide screen. Loss of UHRF1 in the adult-type erythroid cell line HUDEP2 caused global demethylation and HBG activation that was reversed upon localized promoter re-methylation. Conversely, targeted demethylation of the HBG promoters activated their genes in HUDEP2 or primary CD34+ cell-derived erythroblasts. Mutation of MBD2, a CpG-methylation reading component of the NuRD complex, to impair methylation sensitivity recapitulated the effects of promoter demethylation. Our studies demonstrate that localized CpG-methylation at the HBG promoters facilitates developmental silencing and identify a targeted therapeutic approach for b-hemoglobinopathies via epigenomic editing.
2025-06-24 | GSE284291 | GEO
Project description:Beta-hemoglobinopathies caused by mutations in adult-expressed HBB can be treated by re-activating the adjacent paralogous genes HBG1 and HBG2 (HBG), which are normally silenced perinatally. Although HBG expression is induced by global demethylating drugs, their mechanism is poorly understood and toxicity limits their use. We identified the DNMT1-associated maintenance methylation protein UHRF1 as a mediator of HBG repression in a genome-wide screen. Loss of UHRF1 in the adult-type erythroid cell line HUDEP2 caused global demethylation and HBG activation that was reversed upon localized promoter re-methylation. Conversely, targeted demethylation of the HBG promoters activated their genes in HUDEP2 or primary CD34+ cell-derived erythroblasts. Mutation of MBD2, a CpG-methylation reading component of the NuRD complex, to impair methylation sensitivity recapitulated the effects of promoter demethylation. Our studies demonstrate that localized CpG-methylation at the HBG promoters facilitates developmental silencing and identify a targeted therapeutic approach for b-hemoglobinopathies via epigenomic editing.
2025-06-24 | GSE284290 | GEO
Project description:Efficiency of HBG gene activation by the Cas12f/cgRNA system. In a doxycycline-inducible dCas12f-VPR knock-in (KI) HEK293T cell line, transiently transfected plasmids encoding U6, linear, and circular gRNAs targeting HBG1, and cgRNAs targeting mNeonGreen (negative control, NC) to activate HBG gene expression. RNA-seq analysis showed that cgRNAs exhibited increased efficiency in the target gene HBG1 and slight lower specificity when compared with U6 and linear gRNAs.
2024-03-12 | GSE261105 | GEO
Project description:Heterorhabditis indica isolate:NBAII HBG Genome sequencing
| PRJNA656903 | ENA
Project description:Gene expression analysis of human sickle cell disease (SCD) and healthy donor (HD) CD34+ hematopoietic stem/progenitor cells (HSPCs) treated with CRISPR/Cas9 targeting the HBG promoters or untreated samples
| PRJNA1045560 | ENA
Project description:The human genome contains regulatory DNA elements (enhancers, silencers, insulators) that can recruit proteins to activate or repress transcription of distal genes. Interspersed are DNA intervals without any known coding or regulatory capacity. Here, we show that these intrinsically non-regulatory DNA stretches can allow gene silencing by keeping enhancers at distance. During development, the fetal globin HBG genes recruit activated repressor proteins to their promoters. This enables the HBG genes to silence and ignore the distal super-enhancer, which subsequently acts on and activates the downstream adult HBD and HBB genes. We found that forced linear recruitment of the super-enhancer, bringing it immediately upstream of the otherwise intact HBG gene promoters, results in significant HBG reactivation and partial HBB inactivation in adult erythroid cells and ex vivo differentiated human hematopoietic stem and progenitor cells. Forced HBG reactivation is accomplished by CRISPR-Cas9 deletions of the intervening 25 kilobases sequence interval. Additionally, it can be achieved by inversions that leave this interval intact and proximal, but no longer situated between the enhancer and HBG genes. We conclude that the HBG genes must be at substantial linear distance to bypass activation by the super-enhancer and activate their promoter-encoded silencing program in adulthood. Overall, this assigns a functional role to seemingly non-regulatory segments in our genome: by providing linear separation they may support genes to autonomously control their transcriptional response to distal enhancers.
2025-08-05 | GSE274030 | GEO
Project description:The human genome contains regulatory DNA elements (enhancers, silencers, insulators) that can recruit proteins to activate or repress transcription of distal genes. Interspersed are DNA intervals without any known coding or regulatory capacity. Here, we show that these intrinsically non-regulatory DNA stretches can allow gene silencing by keeping enhancers at distance. During development, the fetal globin HBG genes recruit activated repressor proteins to their promoters. This enables the HBG genes to silence and ignore the distal super-enhancer, which subsequently acts on and activates the downstream adult HBD and HBB genes. We found that forced linear recruitment of the super-enhancer, bringing it immediately upstream of the otherwise intact HBG gene promoters, results in significant HBG reactivation and partial HBB inactivation in adult erythroid cells and ex vivo differentiated human hematopoietic stem and progenitor cells. Forced HBG reactivation is accomplished by CRISPR-Cas9 deletions of the intervening 25 kilobases sequence interval. Additionally, it can be achieved by inversions that leave this interval intact and proximal, but no longer situated between the enhancer and HBG genes. We conclude that the HBG genes must be at substantial linear distance to bypass activation by the super-enhancer and activate their promoter-encoded silencing program in adulthood. Overall, this assigns a functional role to seemingly non-regulatory segments in our genome: by providing linear separation they may support genes to autonomously control their transcriptional response to distal enhancers.
2025-08-05 | GSE274029 | GEO
Project description:Sickle cell disease (SCD) is a severe genetic disease caused by a mutation affecting the production of the β-globin chain. Its clinical severity is mitigated by the co-inheritance of mutations that reactivate the production of fetal hemoglobin (HbF) in adults. Here, we investigated the epigenetic regulation of the HBG genes and developed a novel approach based on programmable epigenome editing. Analysis of epigenetic marks at the HBG promoters revealed a distinct pattern of modifications in adult versus fetal erythroid cells. Our studies showed efficient HBG reactivation in the HEK293T cell line and in the progeny of hematopoietic stem and progenitor cells (HSPCs) when using activating epigenome editors targeting the HBG promoters, reaching up to 50% of HbF production and a substantial correction of the sickling phenotype. Our findings highlight the pivotal role of epigenetic modifications in the regulation of the β-globin locus and demonstrate that epigenome reprogramming represents a promising alternative to DNA-cleaving enzymes. This approach mitigates the risks associated with genotoxicity, providing a safe and effective strategy for treating SCD.
2025-05-15 | GSE283100 | GEO
Project description:Sickle cell disease (SCD) is one of the most common inherited hemoglobinopathy disorders that affects millions of people worldwide. Reactivation of HBG (HBG1, HBG2) gene expression and induction of fetal hemoglobin (HbF) is an important therapeutic strategy for ameliorating the clinical symptoms and severity of SCD. Hydroxyurea is the only US FDA-approved drug with proven efficacy to induce HbF in SCD patients, yet serious complications have been associated with its use. Over the last three decades, numerous additional pharmacological agents that reactivate HBG transcription in vitro have been investigated, but few have proceeded to FDA approval, with the exception of arginine butyrate and decitabine; however, neither drug met the requirements for routine clinical use due to difficulties with oral delivery and inability to achieve therapeutic levels. Thus, novel approaches that produce sufficient efficacy, specificity, and sustainable HbF induction with low adverse effects are desirable. More recently, microRNAs (miRNAs) have gained attention for their diagnostic and therapeutic potential to treat various diseases ranging from cancer to Alzheimer's disease via targeting oncogenes and their gene products. Thus, it is plausible that miRNAs that target HBG regulatory genes may be useful for inducing HbF as a treatment for SCD. Our laboratory and others have documented the association of miRNAs with HBG activation or suppression via silencing transcriptional repressors and activators, respectively, of HBG expression. Herein, we review progress made in understanding molecular mechanisms of miRNA-mediated HBG regulation and discuss the extent to which molecular targets of HBG might be suitable prospects for development of SCD clinical therapy. Lastly, we discuss challenges with the application of miRNA delivery in vivo and provide potential strategies for overcoming barriers in the future.
| S-EPMC9098152 | biostudies-literature