Similar Datasets
Project description:Genetic manipulations to increase fetal hemoglobin (HbF, α2γ2) in postnatal red blood cells (RBCs) can alleviate β-thalassemia and sickle cell disease. We compared five strategies in CD34+ hematopoietic stem and progenitor cells, using either Cas9 nuclease, which creates uncontrolled indel mixtures, or adenine base editors (ABE), which generate more precise nucleotide changes. The most potent modification was ABE generation of γ-globin (HBG1/HBG2) −175 A>G, which creates a promoter binding motif for the transcriptional activator TAL1. In erythroid colonies with >87.5% on-target edits, those with −175 A>G expressed 81 ± 7% HbF, versus 17 ± 11% in unedited controls. In comparison, HbF levels were lower and more variable in erythroid cells modified with either of two Cas9 nuclease strategies with similar editing efficiencies, being 32 ± 19% when a BCL11A repressor binding motif in the γ-globin promoter was targeted and 52 ± 13% when the +58 BCL11A erythroid enhancer was targeted. Contrary to currently accepted models of γ-globin regulation, HbF levels varied significantly with different Cas9 indels that disrupted the γ-globin promoter BCL11A binding motif. The −175 A>G base edit also induced HbF more potently than did the Cas9 nuclease approaches in RBCs generated after transplantation of modified normal or SCD patient CD34+ cells into mice. Our data suggest a strategy for potent, uniform induction of HbF and provide insights into γ-globin gene regulation. More generally, we demonstrate that diverse indels generated by Cas9 nuclease can cause unexpected variations in biological outcomes that can be circumvented by base editing, with important implications for therapeutic gene editing efforts.
2023-04-28 | GSE228819 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below.
2010-06-28 | GSE22369 | GEO
Project description:Genome editing to correct a defective β-globin gene or induce fetal globin (HbF) for patients with beta-hemoglobinopathies has the potential to be a curative strategy available to all. HbF reactivation has long been an area of intense interest given the HbF inhibition of sickle hemoglobin (HbS) polymerization. Patients with HbS who also have high HbF tend to have less severe or even minimal clinical manifestations. Approaches to genetically engineer high HbF include de novo generation of naturally occurring hereditary persistence of fetal hemoglobin (HPFH) mutations, editing of transcriptional HbF repressors or their binding sites and/or regulating epigenetic intermediates controlling HbF expression. Recent preclinical and early clinical trial data show encouraging results; however, long-term follow-up is lacking, and the safety and efficacy concerns of genome editing remain.
| S-EPMC7673473 | biostudies-literature
Project description:This SuperSeries is composed of the following subset Series: GSE22366: Primary human erythroid progenitor cells HDAC1 and HDAC2 shRNA knockdown samples GSE22367: Primary human erythroid progenitor cells SAHA treatment samples GSE22368: Primary human erythroid progenitor cells NK57 treatment samples Refer to individual Series
2010-07-29 | E-GEOD-22369 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2015-11-02 | E-GEOD-71422 | biostudies-arrayexpress
Project description:Fetal hemoglobin (HbF) induction therapy has become the most promising strategy for treating β-hemoglobinopathies, including sickle-cell diseases and β-thalassemia. However, subtle but critical structural difference exists between HbF and normal adult hemoglobin (HbA), which inevitably leads to reduced binding of the endogenous modulator 2,3-bisphosphoglycerate (2,3-BPG) to HbF and thus increased oxygen affinity and decreased oxygen transport efficiency of HbF. We combined the oxygen equilibrium experiments, resonance Raman (RR) spectroscopy, and molecular docking modeling, and we discuss 2 phthalides, z-butylidenephthalide and z-ligustilide, that can effectively lower the oxygen affinity of HbF. They adjust it to a level closer to that of HbA and make it a more satisfactory oxygen carrier for adults. From the oxygen equilibrium curve measurements, we show that the 2 phthalides are more effective than 2,3-BPG for modulating HbF. The RR spectra show that phthalides allosterically stabilize the oxygenated HbF in the low oxygen affinity conformation, and the molecular docking modeling reveals that the 2 chosen phthalides interact with HbF via the cleft around the γ1/γ2 interface with a binding strength ∼1.6 times stronger than that of 2,3-BPG. We discuss the implications of z-butylidenephthalide and z-ligustilide in boosting the efficacy of HbF induction therapy to mitigate the clinical severities of β-hemoglobinopathies.
| S-EPMC6517670 | biostudies-literature
Project description:Fetal hemoglobin (HbF) inhibits the root cause of sickle pathophysiology, sickle hemoglobin polymerization. Individuals who naturally express high levels of HbF beyond infancy thus receive some protection from sickle complications. To mimic this natural genetic experiment using drugs, one guiding observation was that HbF is increased during recovery of bone marrow from extreme stress. This led to evaluation and approval of the cytotoxic (cell killing) drug hydroxyurea to treat sickle cell disease. Cytotoxic approaches are limited in potency and sustainability, however, since they require hematopoietic reserves sufficient to repeatedly mount recoveries from stress that destroys their counterparts, and such reserves are finite. HbF induction even by stress ultimately involves chromatin remodeling of the gene for HbF (HBG), therefore, a logical alternative approach is to directly inhibit epigenetic enzymes that repress HBG-implicated enzymes include DNA methyltransferase 1, histone deacetylases, lysine demethylase 1, protein arginine methyltransferase 5, euchromatic histone lysine methyltransferase 2 and chromodomain helicase DNA-binding protein 4. Clinical proof-of-principle that this alternative, noncytotoxic approach can generate substantial HbF and total hemoglobin increases has already been generated. Thus, with continued careful attention to fundamental biological and pharmacologic considerations (reviewed herein), there is potential that rational, molecular-targeted, safe and highly potent disease-modifying therapy can be realized for patients with sickle cell disease, with the accessibility and cost-effective properties needed for world-wide effect.
| S-EPMC6029722 | biostudies-literature
Project description:Elements within the γ-hemoglobin promoters (HBG1 and HBG2) function to bind transcription complexes that mediate repression of fetal hemoglobin expression. Sickle cell disease (SCD) subjects with a 13-bp deletion in the HBG1 promoter exhibit a clinically favorable hereditary persistence of fetal hemoglobin (HPFH) phenotype. We developed TALENs targeting the homologous HBG promoters to de-repress fetal hemoglobin. Transfection of human CD34+ cells with TALEN mRNA resulted in indel generation in HBG1 (43%) and HBG2 (74%) including the 13-bp HPFH deletion (∼6%). Erythroid differentiation of edited cells revealed a 4.6-fold increase in γ-hemoglobin expression as detected by HPLC. Assessment of TALEN-edited CD34+ cells in vivo in a humanized mouse model demonstrated sustained presence of indels in hematopoietic cells up to 24 weeks. Indel rates remained unchanged following secondary transplantation consistent with editing of long-term repopulating stem cells (LT-HSCs). Human γ-hemoglobin expressing F cells were detected by flow cytometry approximately 50% more frequently in edited animals compared to mock. Together, these findings demonstrate that TALEN-mediated indel generation in the γ-hemoglobin promoter leads to high levels of fetal hemoglobin expression in vitro and in vivo, suggesting that this approach can provide therapeutic benefit in patients with SCD or β-thalassemia.
| S-EPMC6348980 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2015-11-02 | GSE71422 | GEO
Project description:Induction of fetal hemoglobin (HbF) via clustered regularly interspaced short palindromic repeats/Cas9-mediated disruption of DNA regulatory elements that repress ?-globin gene (HBG1 and HBG2) expression is a promising therapeutic strategy for sickle cell disease (SCD) and ?-thalassemia, although the optimal technical approaches and limiting toxicities are not yet fully defined. We disrupted an HBG1/HBG2 gene promoter motif that is bound by the transcriptional repressor BCL11A. Electroporation of Cas9 single guide RNA ribonucleoprotein complex into normal and SCD donor CD34+ hematopoietic stem and progenitor cells resulted in high frequencies of on-target mutations and the induction of HbF to potentially therapeutic levels in erythroid progeny generated in vitro and in vivo after transplantation of hematopoietic stem and progenitor cells into nonobese diabetic/severe combined immunodeficiency/Il2r?-/-/KitW41/W41 immunodeficient mice. On-target editing did not impair CD34+ cell regeneration or differentiation into erythroid, T, B, or myeloid cell lineages at 16 to 17 weeks after xenotransplantation. No off-target mutations were detected by targeted sequencing of candidate sites identified by circularization for in vitro reporting of cleavage effects by sequencing (CIRCLE-seq), an in vitro genome-scale method for detecting Cas9 activity. Engineered Cas9 containing 3 nuclear localization sequences edited human hematopoietic stem and progenitor cells more efficiently and consistently than conventional Cas9 with 2 nuclear localization sequences. Our studies provide novel and essential preclinical evidence supporting the safety, feasibility, and efficacy of a mechanism-based approach to induce HbF for treating hemoglobinopathies.
| S-EPMC6855127 | biostudies-literature