Project description:Our research has demonstrated that G-CSF impedes engraftment of CRISPR-Cas9 gene edited human hematopoietic stem cells (HSCs) by exacerbating p53-mediated DNA damage response. Results in this study suggest that the potential for G-CSF to exacerbate HSC toxicity mediated by DNA-damaging nucleases should be considered in autologous HSC gene therapy clinical trials.
Project description:Sickle cell disease (SCD) results from a point mutation in the β-globin gene forming hemoglobin S (HbS), which polymerizes in deoxygenated erythrocytes, triggering recurrent painful vaso-occlusive crises and chronic hemolytic anemia. Reactivation of fetal Hb (HbF) expression ameliorates these symptoms of SCD. Nuclear factor (erythroid derived-2)–like 2 (Nrf2) is a transcription factor that triggers cytoprotective and antioxidant pathways to limit oxidative damage and inflammation and increases HbF synthesis in CD34+ stem cell–derived erythroid progenitors. We investigated the ability of dimethyl fumarate (DMF), a small-molecule Nrf2 agonist, to activate γ-globin transcription and enhance HbF in tissue culture, murine and primate models. DMF recruited Nrf2 to the γ-globin promoters and the locus control region of the β-globin locus in erythroleukemia cells, elevated HbF in SCD donor–derived erythroid progenitors, and reduced hypoxia-induced sickling. Chronic DMF administration in SCD mice induced HbF and increased Nrf2-dependent genes to detoxify heme and limit inflammation. This improved hematological parameters, reduced plasma-free Hb, and attenuated inflammatory markers. Chronic DMF administration to nonanemic primates increased γ-globin mRNA in BM and HbF protein in red cells. DMF represents a potential therapy for SCD to induce HbF and augment vasoprotection and heme detoxification
Project description:The fetal-to-adult hemoglobin switch is regulated in a developmental stage-specific manner and reactivation of fetal hemoglobin (HbF) has therapeutic potential for β-hemoglobinopathies. Although BCL11A and ZBTB7A interact with their coregulators, reportedly mediating most γ-globin transcriptional silencing in erythroid in trans, and in cis, the molecular mechanism underlying the epigenetic dysregulation of the switch remains largely unclear. Here we showed that epigenetic inactivation of an ETS2 repressor factor (ERF) reactivates γ-globin expression during stress erythropoiesis, and ERF depletion elevates γ-globin in erythroid cells and in erythroid progenies from the edited HSPCs engrafted into immunodeficient mice. ERF represses γ-globin by directly binding to two motifs regulating HBG expression, independently of the major HbF repressors BCL11A and ZBTB7A. We further uncovered that an lncRNA, RP11-196G18.23 mediates ERF promoter hypermethylation resulting in reactivation of g-globin. Herein, the epigenetic alterations were identified as novel modulators ameliorating the severity of b-thalassemia, thus providing novel therapeutic targets for β-hemoglobinopathies.
Project description:The fetal-to-adult hemoglobin switch is regulated in a developmental stage-specific manner and reactivation of fetal hemoglobin (HbF) has therapeutic potential for β-hemoglobinopathies. Although BCL11A and ZBTB7A interact with their coregulators, reportedly mediating most γ-globin transcriptional silencing in erythroid in trans, and in cis, the molecular mechanism underlying the epigenetic dysregulation of the switch remains largely unclear. Here we showed that epigenetic inactivation of an ETS2 repressor factor (ERF) reactivates γ-globin expression during stress erythropoiesis, and ERF depletion elevates γ-globin in erythroid cells and in erythroid progenies from the edited HSPCs engrafted into immunodeficient mice. ERF represses γ-globin by directly binding to two motifs regulating HBG expression, independently of the major HbF repressors BCL11A and ZBTB7A. We further uncovered that an lncRNA, RP11-196G18.23 mediates ERF promoter hypermethylation resulting in reactivation of g-globin. Herein, the epigenetic alterations were identified as novel modulators ameliorating the severity of b-thalassemia, thus providing novel therapeutic targets for β-hemoglobinopathies.
Project description:Hematopoietic stem cells (HSC) rely on a unique regulatory machinery that facilitates life-long blood production and enables reconstitution of the entire hematopoietic system upon transplantation. However, the biological processes governing human HSC self-renewal and engraftment ability are poorly understood and challenging to recapitulate ex vivo to facilitate robust human HSC expansion. We discovered a novel HSC regulatory protein, MYCT1 (MYCT target 1), that is selectively expressed in endothelial cells (EC) and undifferentiated human HSPCs but becomes drastically downregulated during HSC culture. Lentiviral knockdown of MYCT1 in human foetal liver and cord blood HSPCs revealed a critical role for MYCT1 in governing human HSPC expansion and engraftment ability. Single cell RNAseq of human CB HSPCs after MYCT1 knockdown and overexpression revealed that MYCT1 governs HSC functional competence and modulates cellular properties essential for HSC stemness, such as low mitochondrial metabolic activity. Indeed, restoring the compromised MYCT1 expression in cultured human CB HSPCs improved ex vivo expansion of the most undifferentiated human HSPCs and enhanced their engraftment ability. We found that MYCT1 is localized in the endosomal membrane and interacts with vesicle trafficking regulators and signalling machinery essential for HSC and EC function. Loss of MYCT1 led to excessive endocytosis and hyperactive signalling responses to cytokines, whereas restoring MYCT1 expression in cultured CB HSPCs balanced the abnormal endocytosis associated with prolonged culture and fine-tuned signalling responses. Our work identifies MYCT1-moderated endocytosis and environmental sensing as an essential regulatory mechanism required to preserve human HSC stemness, and pinpoints silencing of MYCT1 as a critical contributor to the dysfunction of cultured human HSCs that needs to be addressed to improve human HSC culture strategies.
Project description:Differences in the amount of fetal hemoglobin (HbF) that persists into adulthood affect the severity of sickle cell disease and the beta-thalassemia syndromes. Genetic association studies have identified sequence variants in the gene BCL11A that influence HbF levels. Here we examine BCL11A as a potential regulator of HbF expression. The high HbF BCL11A genotype is associated with reduced BCL11A expression. Moreover, abundant expression of full-length forms of BCL11A is developmentally restricted to adult erythroid cells. Down-regulation of BCL11A expression in primary adult erythroid cells leads to robust HbF expression. Consistent with a direct role of BCL11A in globin gene regulation, we find that BCL11A occupies several discrete sites in the beta-globin gene cluster. BCL11A emerges as a therapeutic target for reactivation of HbF in beta-hemoglobin disorders. Expression clone label: FBB (4 different subclones, with 2 arrays each), Control label: MelBirA Experiment Overall Design: Microarray expression analysis from parental control mouse erythroleukemia (MEL) cells containing the BirA enzyme (MelBirA cells) and cells containing tagged versions (FLAG-Biotag) of BCL11A. Two control datasets and eight datasets from four subclones containing tagged BCL11A are included.
Project description:mRNA microarray profiling was performed on healthy gingival biopsies from nonhuman primates (NHPs) (between 3 and 23 years old, and periodontitis gingival biopsies from NHPs (12-22 years old)