Growth factor independence 1b (Gfi1b) is required for erythroid cell maturation and regulates embryonic globin expression
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE54206 | GEO | 2014/12/31
SECONDARY ACCESSION(S): PRJNA235883
REPOSITORIES: GEO
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Project description:Growth factor independence 1b (GFI1B) is a DNA binding repressor of transcription with vital functions in hematopoiesis. Gfi1b-null embryos die at midgestation very likely due to defects in erythro- and megakaryopoiesis. To analyze the full functionality of Gfi1b, we used conditionally deficient mice that harbor floxed Gfi1b alleles and inducible (Mx-Cre, Cre-ERT) or erythroid specific (EpoR-Cre) Cre expressing transgenes. In contrast to the germline knockout, EpoR-Cre mediated erythroid specific ablation of Gfi1b allows full gestation, but causes perinatal lethality with very few mice surviving to adulthood. Both the embryonic deletion of Gfi1b by EpoR-Cre and the deletion in adult mice by Mx-Cre or Cre-ERT leads to reduced numbers of erythroid precursors, perturbed and delayed erythroid maturation, anemia and extramedullary erythropoiesis. Global expression analyses showed that the Hba-x, Hbb-bh1 and Hbb-y embryonic globin genes were upregulated in Gfi1b deficient TER119+ fetal liver cells over the gestation period from day 12.5-17.5 p.c. and an increased level of Hbb-bh1 and Hbb-y embryonic globin gene expression was even maintained in adult Gfi1b deficient mice. While the expression of Bcl11a, a regulator of embryonic globin expression was not affected by Gfi1b deficiency, the expression of Gata1 was reduced and the expression of Sox6, also involved in globin switch, was almost entirely lost when Gfi1b was absent. These findings establish Gfi1b as a regulator of embryonic globin expression and embryonic and adult erythroid maturation.
| S-EPMC4011847 | biostudies-literature
Project description:Growth factor independence 1b (Gfi1b) is a DNA binding repressor of transcription with vital functions in hematopoiesis. Gfi1b-null embryos die at midgestation very likely due to defects in erythro- and megakaryopoiesis. To analyze the full functionality of Gfi1b in erythropoiesis, we used conditionally deficient mice that harbor floxed Gfi1b alleles and the Mx-Cre transgene inducible by pIpC treatment. We used bone marow cells from 12 weeks old wild type C57BL/6 mice or conditional Gfi1b knock-out mice, both carrying the Mx-cre transgene induced by five treatments with pIpC (500µg each) every other day and sacrificed 42 days after the first injection. Ter119 positive erythroid cells were isolated by flow cytometry and RNA from these cells was isolated using the Trizol procedure according to the manufacturers instructions for gene expression analysis on Affymetrix MOE_430 2.0 expression arrays (GPL 1261)
2014-12-31 | GSE54205 | GEO
Project description:Growth factor independence 1b (Gfi1b) is a DNA binding repressor of transcription with vital functions in hematopoiesis. Gfi1b-null embryos die at midgestation very likely due to defects in erythro- and megakaryopoiesis. To analyze the full functionality of Gfi1b in embryonic erythropoiesis, we used conditionally deficient mice that harbor floxed Gfi1b alleles and one EpoR-Cre knock-in allele. We used fetal liver cells from wild type C57BL/6 embryos or conditional Gfi1b knock-out embryos at day 14.5 p.c., both carrying one EpoR-cre knock-in allele. Ter119 positive erythroid cells were isolated by flow cytometry and RNA from these cells was isolated using the Trizol procedure according to the manufacturers instructions for gene expression analysis on Affymetrix Gene 1.0 ST arrays (GPL 6246)
2014-12-31 | GSE54204 | GEO
Project description:Growth factor independence 1b (Gfi1b) is required for erythroid cell maturation and regulates embryonic globin expression
| PRJNA235883 | ENA
Project description:Growth Factor Independence-1B (Gfi-1B) is a transcriptional repressor essential for erythropoiesis and megakaryopoiesis. Targeted gene disruption of Gfi-1B in mice leads to embryonic lethality due to failure to produce definitive erythrocytes, hindering the study of Gfi-1B function in adult hematopoiesis. We here show that, in humans, Gfi-1B controls the development of erythrocytes and megakaryocytes by regulating the proliferation and differentiation of bipotent erythro-megakaryocytic progenitors (MEP). We further identify in this cell population the type III transforming growth factor-? receptor gene, TGFBR3, as a direct target of Gfi-1B. Knock down of Gfi-1B results in altered TGF? signaling as shown by the increase in Smad2 phosphorylation and its inability to associate to the Transcription Intermediary Factor 1? (TIF1?). Because Smad2/TIF1? complex is known to specifically regulate erythroid differentiation, we propose that, by repressing the transforming growth factor-? receptor III (T?R?II) expression, Gfi-1B favors the Smad2/TIF1? interaction downstream of TGF? signaling, allowing immature progenitors to differentiate toward the erythroid lineage.
2010-04-19 | E-MEXP-2560 | biostudies-arrayexpress
Project description:Donor-matched transplantation of hematopoietic stem cells (HSCs) is widely used to treat hematologic malignancies but is associated with high mortality. The expansion of HSC numbers and their mobilization into the bloodstream could significantly improve therapy. We report here that adult mice conditionally deficient for the transcription Growth factor independence 1b (Gfi1b) show a significant expansion of functional HSCs in the bone marrow and blood. Despite this expansion, Gfi1b(ko/ko) HSCs retain their ability to self-renew and to initiate multilineage differentiation but are no longer quiescent and contain elevated levels of reactive oxygen species. Treatment of Gfi1b(ko/ko) mice with N-acetyl-cystein significantly reduced HSC numbers indicating that increased reactive oxygen species levels are at least partially responsible for the expansion of Gfi1b-deficient HSCs. Moreover, Gfi1b(-/-) HSCs show decreased expression of CXCR4 and Vascular cell adhesion protein-1, which are required to retain dormant HSCs in the endosteal niche, suggesting that Gfi1b regulates HSC dormancy and pool size without affecting their function. Finally, the additional deletion of the related Gfi1 gene in Gfi1b(ko/ko) HSCs is incompatible with the maintenance of HSCs, suggesting that Gfi1b and Gfi1 have partially overlapping functions but that at least one Gfi gene is essential for the generation of HSCs.
| S-EPMC3321835 | biostudies-literature
Project description:Ldb1 and erythroid partners SCL, GATA-1, and LMO2 form a complex that is required to establish spatial proximity between the β-globin locus control region and gene and for transcription activation during erythroid differentiation. Here we show that Ldb1 controls gene expression at multiple levels. Ldb1 stabilizes its erythroid complex partners on β-globin chromatin, even though it is not one of the DNA-binding components. In addition, Ldb1 is necessary for enrichment of key transcriptional components in the locus, including P-TEFb, which phosphorylates Ser2 of the RNA polymerase C-terminal domain for efficient elongation. Furthermore, reduction of Ldb1 results in the inability of the locus to migrate away from the nuclear periphery, which is necessary to achieve robust transcription of β-globin in nuclear transcription factories. Ldb1 contributes these critical functions at both embryonic and adult stages of globin gene expression. These results implicate Ldb1 as a factor that facilitates nuclear relocation for transcription activation.
| S-EPMC2953839 | biostudies-literature
Project description:The fetal and adult globin genes in the human ?-globin cluster on chromosome 11 are sequentially expressed to achieve normal hemoglobin switching during human development. The pharmacological induction of fetal ?-globin (HBG) to replace abnormal adult sickle ?S-globin is a successful strategy to treat sickle cell disease; however the molecular mechanism of ?-gene silencing after birth is not fully understood. Therefore, we performed global gene expression profiling using primary erythroid progenitors grown from human peripheral blood mononuclear cells to characterize gene expression patterns during the ?-globin to ?-globin (?/?) switch observed throughout in vitro erythroid differentiation.We confirmed erythroid maturation in our culture system using cell morphologic features defined by Giemsa staining and the ?/?-globin switch by reverse transcription-quantitative PCR (RT-qPCR) analysis. We observed maximal ?-globin expression at day 7 with a switch to a predominance of ?-globin expression by day 28 and the ?/?-globin switch occurred around day 21. Expression patterns for transcription factors including GATA1, GATA2, KLF1 and NFE2 confirmed our system produced the expected pattern of expression based on the known function of these factors in globin gene regulation. Subsequent gene expression profiling was performed with RNA isolated from progenitors harvested at day 7, 14, 21, and 28 in culture. Three major gene profiles were generated by Principal Component Analysis (PCA). For profile-1 genes, where expression decreased from day 7 to day 28, we identified 2,102 genes down-regulated > 1.5-fold. Ingenuity pathway analysis (IPA) for profile-1 genes demonstrated involvement of the Cdc42, phospholipase C, NF-K?, Interleukin-4, and p38 mitogen activated protein kinase (MAPK) signaling pathways. Transcription factors known to be involved in ?-and ?-globin regulation were identified.The same approach was used to generate profile-2 genes where expression was up-regulated over 28 days in culture. IPA for the 2,437 genes with > 1.5-fold induction identified the mitotic roles of polo-like kinase, aryl hydrocarbon receptor, cell cycle control, and ATM (Ataxia Telangiectasia Mutated Protein) signaling pathways; transcription factors identified included KLF1, GATA1 and NFE2 among others. Finally, profile-3 was generated from 1,579 genes with maximal expression at day 21, around the time of the ?/?-globin switch. IPA identified associations with cell cycle control, ATM, and aryl hydrocarbon receptor signaling pathways.The transcriptome analysis completed with erythroid progenitors grown in vitro identified groups of genes with distinct expression profiles, which function in metabolic pathways associated with cell survival, hematopoiesis, blood cells activation, and inflammatory responses. This study represents the first report of a transcriptome analysis in human primary erythroid progenitors to identify transcription factors involved in hemoglobin switching. Our results also demonstrate that the in vitro liquid culture system is an excellent model to define mechanisms of global gene expression and the DNA-binding protein and signaling pathways involved in globin gene regulation.
| S-EPMC3353202 | biostudies-literature
Project description:The Krüppel-like factor (KLF) family dominates highly conserved three zinc finger DNA binding domains at the C-terminus and variable transactivation domains at the N-terminus. Humans possess 18 KLF genes that are differentially expressed in various tissues. Several KLFs recognize a specific CACCC DNA motif that is commonly found within hematopoietic-specific promoters. To investigate those KLFs that are involved in human hemoglobin (Hb) switching, the present study analyzed a previous microarray data set from fetal and adult erythroid cells and validated the mRNA expression levels of 18 KLFs by reverse transcription-quantitative PCR (RT-qPCR). KLF with a decreased expression level in the fetuses was selected for a functional study in human erythroid progenitor cells using lentiviral-based short hairpin RNA knockdown. The fetuses demonstrated a lower level of KLF4 mRNA expression when compared with the adults. Downregulation of KLF4 in erythroid progenitor cells from healthy individuals and individuals with β0-thalassemia/HbE evidenced the increasing embryonic and fetal globin mRNA expression with neither significant cytotoxicity nor gene expression alteration of the examined globin regulators, KLF1, B-cell lymphoma/leukemia 11A and lymphoma/leukemia-related factor. These findings demonstrate that the downregulation of KLF4 is associated with increased embryonic and fetal globin gene expression in human erythroid progenitor cells. Moreover, identifying putative compounds or molecular approaches that effectively downregulate KLF4 and further induce embryonic globin expression may provide an alternative therapeutic strategy for α-globin substitution in severe α-thalassemia.
| S-EPMC8383760 | biostudies-literature
Project description:We previously demonstrated that ubiquitously expressed CP2c exerts potent erythroid-specific transactivation of alpha-globin through an unknown mechanism. This mechanism is reported here to involve specific CP2 splice variants and protein inhibitor of activated STAT1 (PIAS1). We identify a novel murine splice isoform of CP2, CP2b, which is identical to CP2a except that it has an additional 36 amino acids encoded by an extra exon. CP2b has an erythroid cell-specific transcriptional activation domain, which requires the extra exon and can form heteromeric complexes with other CP2 isoforms, but lacks the DNA binding activity found in CP2a and CP2c. Transcriptional activation of alpha-globin occurred following dimerization between CP2b and CP2c in erythroid K562 and MEL cells, but this dimerization did not activate the alpha-globin promoter in nonerythroid 293T cells, indicating that an additional erythroid factor is missing in 293T cells. PIAS1 was confirmed as a CP2 binding protein by the yeast two-hybrid screen, and expression of CP2b, CP2c, and PIAS1 in 293T cell induced alpha-globin promoter activation. These results show that ubiquitously expressed CP2b exerts potent erythroid cell-specific alpha-globin gene expression by complexing with CP2c and PIAS1.
| S-EPMC1168829 | biostudies-literature