Project description:Human genetics has validated de-repression of fetal gamma globin (HBG) in adult erythroblasts as a powerful therapeutic paradigm in diseases involving defective adult beta globin (HBB)1. To identify novel factors involved in the switch from HBG to HBB expression, we performed Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq)2 on discrete sorted erythroblast populations derived from bone marrow (BM) or cord blood (CB) progenitors, representing adult and fetal states, respectively. Comparison of the ATAC-seq profiles revealed enrichment of NFI DNA binding motifs and increased chromatin accessibility at the NFIX promoter in BM populations relative to CB populations, suggesting that NFIX may repress HBG. NFIX knockdown in BM cells increased HBG mRNA and fetal hemoglobin (HbF) protein levels, coincident with increased chromatin accessibility and decreased DNA methylation at the HBG promoter. Conversely, overexpression of NFIX in CB cells reduced HbF levels. Identification of NFIX as a novel target for HbF activation has potential implications in the development of therapeutics for hemoglobinopathies.
Project description:Human genetics has validated de-repression of fetal gamma globin (HBG) in adult erythroblasts as a powerful therapeutic paradigm in diseases involving defective adult beta globin (HBB)1. To identify factors involved in the switch from HBG to HBB expression, we performed Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq)2 on sorted erythroid lineage cells derived from bone marrow (BM) or cord blood (CB), representing adult and fetal states, respectively. BM to CB cell ATAC-seq profile comparisons revealed genome-wide enrichment of NFI DNA binding motifs and increased NFIX promoter chromatin accessibility, suggesting that NFIX may repress HBG. NFIX knockdown in BM cells increased HBG mRNA and fetal hemoglobin (HbF) protein levels, coincident with increased chromatin accessibility and decreased DNA methylation at the HBG promoter. Conversely, overexpression of NFIX in CB cells reduced HbF levels. Identification and validation of NFIX as a new target for HbF activation has implications in the development of therapeutics for hemoglobinopathies.
Project description:Transcriptional enhancers can be in physical proximity with their target genes via chromatin looping. The enhancer at the beta-globin locus (LCR) contacts the fetal (HBG) and adult (HBB) type beta-globin genes during corresponding developmental stages. We previously demonstrated that forcing proximity between the LCR and HBG genes in cultured adult-stage erythroid cells can activate HBG transcription. Activation of HBG expression in erythroid cells is of benefit to patients with sickle cell disease. Here, using the beta-globin locus as a model we provide proof-of-concept at the organismal level that forced enhancer re-wiring might present a strategy to alter gene expression for therapeutic purposes. Hematopoietic stem and progenitor cells (HSPC) from mice bearing human beta-globin genes were transduced with lentiviral vectors expressing a synthetic transcription factor (ZF-Ldb1) that fosters LCR-HBG contacts. When engrafted into host animals, HSPCs gave rise to adult-type erythroid cells with elevated HBG expression. Vectors containing ZF-Ldb1 were optimized for activity in cultured human and rhesus erythroid cells. Upon transplantation into rhesus macaques, erythroid cells from HSPCs expressing ZF-Ldb1 displayed elevated HBG production. These findings in two animal models suggest that forced redirection of gene regulatory elements may be used to alter gene expression to treat disease.
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.
Project description:ChIP-seq analysis of ZHX3 in IMR-90 cells. We found that ZHX3 is enriched at the promoter site of target genes.
2022-01-01 | GSE184992 | GEO
Project description:Therapeutic base editing of HBG promoter to reactivate high level of gamma-globin expression with no detectable off-target mutations
Project description:Therapeutic base editing of HBG promoter to reactivate high level of gamma-globin expression with no detectable off-target mutations
Project description:This experiment is designed to verify that the targeted CRISPRi indeed bind specifically at the intended site (KLF2 binding site 1 on the miR-125b-1 promoter) in MDA-MB-231 cells. At the same time, off-target binding can be explored.
Project description:To identify potential single-guide RNA (sgRNAs) contaminants in the GMP HBG-sgRNA, we performed SMARTer smRNA-sequencing (Takara). 80.79% of the 5' spacer sequence perfectly matched the targeting sgRNA sequence and no evidence of contaminants sgRNAs that could target other genomic regions.