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. BCL11A siRNA label: B, NT siRNA label: N Experiment Overall Design: Microarray expression analysis from CD34-derived erythroid progenitors treated with either non-targeting (NT) control siRNAs or BCL11A targeting siRNAs. Six samples from the NT control and six samples from the BCL11A siRNA treatment are included. Cells were harvested on day 7 of erythroid differentiation after introduction of siRNAs on day 0 of the differentiation protocol. Experiment Overall Design: 6 BCL11A siRNA datasets, 6 control (NT) datasets
Project description:BCL11A represses gamma globin expression by binding to the gamma globin gene (HBG1 and HBG2) promoters. Genome editing of the BCL11A erythroid enhancer in the intron 2 of BCL11A gene or the BCL11A binding site at the HBG1/2 promoters disrupts this pathway and leads to gamma globin induction. Transcriptomic profiling of erythroid cells derived from human CD34+ cells edited at either target site using CRISPR-Cas9 revealed broader transcriptome perturbation when edited at the BCL11A erythroid enhancer.
Project description:Ashley R, Yan H, Wang N, Hale J, Dulmovits BM, Papoin J, Olive ME, Udeshi ND, Carr SA, Vlachosa A, Lipton JM, Da Costa L, Hillyer C, Kinet S, Taylor N, Mohandas N, Narla A, Blanc L. 2019. Despite the effective clinical use of steroids for the treatment of Diamond Blackfan anemia (DBA), the mechanistic bases via which glucocorticoids regulate human erythropoiesis remain poorly understood. Here, we report that the sensitivity of erythroid differentiation to dexamethasone (Dex) is dependent on the developmental origin of human CD34+ progenitor cells, specifically increasing the expansion of CD34+ progenitors from peripheral blood (PB) but not cord blood (CB). Dexamethasone treatment of erythroid-differentiated PB, but not CB, CD34+ progenitors resulted in the expansion of a novel CD34+CD36+CD71hiCD105med immature colony-forming unit-erythroid (CFU-E) population. Furthermore, proteomics analyses revealed the induction of distinct proteins in dexamethasone-treated PB and CB erythroid progenitors. Dexamethasone treatment of PB progenitors resulted in the specific upregulation of p57Kip2, a Cip/Kip cyclin-dependent kinase inhibitor, and we identified this induction as critical; shRNA-mediated downregulation of p57Kip2, but not the related p27Kip1, significantly attenuated the impact of dexamethasone on erythroid differentiation and inhibited the expansion of the immature CFU-E subset. Notably, in the context of DBA, we found that steroid resistance was associated with a dysregulated p57Kip2 expression. Altogether, these data identify a novel glucocorticoid-responsive human erythroid progenitor and provide new insights into glucocorticoid-based therapeutic strategies for the treatment of patients with DBA.
Project description:Prior evidence indicates that the erythroid cellular response to glucocorticoids (GC) has developmental specificity, namely, that developmentally more advanced cells that are undergoing or have undergone fetal to adult globin switching are more responsive to GC-induced expansion. To investigate the molecular underpinnings of this, we focused on the major developmental globin regulator BCL11A. We compared: a) levels of expression and nuclear content of BCL11A in adult erythroid cells upon GC stimulation; b) response to GC of CD34+ cells from patients with BCL11A microdeletions and reduced BCL11A expression, and; c) response to GC of two cellular models (HUDEP-2 and adult CD34+ cells) before and after reduction of BCL11A expression by shRNA. We observed that: a) GC-expanded erythroid cells from a large cohort of blood donors displayed amplified expression and nuclear accumulation of BCL11A; b) CD34+ cells from BCL11A microdeletion patients generated fewer erythroid cells when cultured with GC compared to their parents, while the erythroid expansion of the patients was similar to that of their parents in cultures without GC, and; c) adult CD34+ cells and HUDEP-2 cells with shRNA-depleted expression of BCL11A exhibit reduced expansion in response to GC. In addition, RNA-seq profiling of shRNA-BCL11A CD34+ cells cultured with and without GC was similar (very few differentially expressed genes), while GC-specific responses (differential expression of GILZ and of numerous additional genes) were observed only in controls cells with unperturbed BCL11A expression. These data indicate that BCL11A is an important participant of certain aspects of the stress pathway sustained by GC.
Project description:Prior evidence indicates that the erythroid cellular response to glucocorticoids (GC) has developmental specificity, namely, that developmentally more advanced cells that are undergoing or have undergone fetal to adult globin switching are more responsive to GC-induced expansion. To investigate the molecular underpinnings of this, we focused on the major developmental globin regulator BCL11A. We compared: a) levels of expression and nuclear content of BCL11A in adult erythroid cells upon GC stimulation; b) response to GC of CD34+ cells from patients with BCL11A microdeletions and reduced BCL11A expression, and; c) response to GC of two cellular models (HUDEP-2 and adult CD34+ cells) before and after reduction of BCL11A expression by shRNA. We observed that: a) GC-expanded erythroid cells from a large cohort of blood donors displayed amplified expression and nuclear accumulation of BCL11A; b) CD34+ cells from BCL11A microdeletion patients generated fewer erythroid cells when cultured with GC compared to their parents, while the erythroid expansion of the patients was similar to that of their parents in cultures without GC, and; c) adult CD34+ cells and HUDEP-2 cells with shRNA-depleted expression of BCL11A exhibit reduced expansion in response to GC. In addition, RNA-seq profiling of shRNA-BCL11A CD34+ cells cultured with and without GC was similar (very few differentially expressed genes), while GC-specific responses (differential expression of GILZ and of numerous additional genes) were observed only in controls cells with unperturbed BCL11A expression. These data indicate that BCL11A is an important participant of certain aspects of the stress pathway sustained by GC.
Project description:Bcl11a is a transcription factor known to regulate lymphoid and erythroid development. Recent bioinformatic analysis of global gene expression patterns has suggested a role for Bcl11a in the development of dendritic cell (DC) lineages. We tested this hypothesis by analyzing the development of DC and other lineages in Bcl11a(-/-) mice. We show that Bcl11a is required for expression of IL-7 receptor (IL-7R) and Flt3 in early hematopoietic progenitor cells. The loss of IL-7R(+) common lymphoid progenitors accounts for previously described lymphoid defects in Bcl11a(-/-) mice. In addition, we found severely decreased numbers of plasmacytoid dendritic cells (pDCs) in Bcl11a(-/-) fetal livers and in the bone marrow of Bcl11a(-/-) fetal liver chimeras. Moreover, Bcl11a(-/-) cells show severely impaired in vitro development of Flt3L-derived pDCs and classical DCs (cDCs). In contrast, we found normal in vitro development of DCs from Bcl11a(-/-) fetal liver cells treated with GM-CSF. These results suggest that the persistent cDC development observed in Bcl11a(-/-) fetal liver chimeras reflects derivation from a Bcl11a- and Flt3-independent pathway in vivo. We compared global gene expression by microarray for donor-derived wild-type and Bcl11a(-/-) populations isolated from chimeric bone marrow to identify Bcl11a target genes that explain its role in hematopoietic progenitors. GMP and MPP populations were sorted from fetal liver chimeras and pooled by donor genotype. RNA was isolated using an RNAqueous-Micro Kit (Ambion) and submitted for amplification, labeling and hybridization. Expression values were analyzed after RMA quantile normalization using ArrayStar software (DNASTAR).
Project description:Bcl11a is a transcription factor known to regulate lymphoid and erythroid development. Recent bioinformatic analysis of global gene expression patterns has suggested a role for Bcl11a in the development of dendritic cell (DC) lineages. We tested this hypothesis by analyzing the development of DC and other lineages in Bcl11a(-/-) mice. We show that Bcl11a is required for expression of IL-7 receptor (IL-7R) and Flt3 in early hematopoietic progenitor cells. The loss of IL-7R(+) common lymphoid progenitors accounts for previously described lymphoid defects in Bcl11a(-/-) mice. In addition, we found severely decreased numbers of plasmacytoid dendritic cells (pDCs) in Bcl11a(-/-) fetal livers and in the bone marrow of Bcl11a(-/-) fetal liver chimeras. Moreover, Bcl11a(-/-) cells show severely impaired in vitro development of Flt3L-derived pDCs and classical DCs (cDCs). In contrast, we found normal in vitro development of DCs from Bcl11a(-/-) fetal liver cells treated with GM-CSF. These results suggest that the persistent cDC development observed in Bcl11a(-/-) fetal liver chimeras reflects derivation from a Bcl11a- and Flt3-independent pathway in vivo. We compared global gene expression by microarray for donor-derived wild-type and Bcl11a(-/-) populations isolated from chimeric bone marrow to identify Bcl11a target genes that explain its role in hematopoietic progenitors.
Project description:Determine the effects of HDAC1/2-selective chemical inhibtion on the gene expression profiles of erythroid progenitors derived from human CD34+ bone marrow cells.
Project description:Genetic depletion of the transcriptional repressor BCL11A in red blood cell precursors alleviates b-hemoglobinopathies by inducing the fetal g-globin genes. However, several additional erythroid genes are regulated by BCL11A and the effects of its deficiency on erythropoiesis are insufficiently described. We discovered that Cas9 disruption of the BCL11A intron 2 erythroid enhancer in CD34+ hematopoietic stem and progenitor cells (HSPCs) according to a clinically approved strategy caused impaired expansion and increased apoptosis of erythroid precursors in vitro and in vivo. Mutant colony-forming unit erythroid (CFU-e), proerythroblasts, and basophilic erythroblasts exhibited dysregulation of 94 genes (> 2-fold change, FDR < 0.05). 25 of which are likely direct targets of BCL11A. Differentially expressed genes were associated with numerous biological pathways that impact cell expansion and survival. Our findings show that BCL11A regulates additional aspects of erythropoiesis beyond g-globin gene repression.