LDB1 complexes in erythroid differentiation
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Project description:We used ChIP-Seq to map Ldb1, Scl and Gata1 binding sites in mouse total bone marrow cells. Together with functional studies comparing gene expression in Murine Erythroleukemia (MEL) cells expressing Ldb1 shRNA or control shRNA and bioinformatics analysis, we systematically determined the transcriptional program controlled by Ldb1 complexes in erythropoiesis. This represents the ChIP-Seq component of the study only To evaluate the role of Ldb1complexes in erythroid gene activation
2013-04-29 | E-GEOD-42843 | biostudies-arrayexpress
Project description:We used ChIP-Seq to map Ldb1, Scl and Gata1 binding sites in mouse total bone marrow cells. Together with functional studies comparing gene expression in Murine Erythroleukemia (MEL) cells expressing Ldb1 shRNA or control shRNA and bioinformatics analysis, we systematically determined the transcriptional program controlled by Ldb1 complexes in erythropoiesis. This represents the ChIP-Seq component of the study only
2013-04-29 | GSE42843 | GEO
Project description:Carbonic anhydrase 1 (Car1), an early specific marker of the erythroid differentiation, has been used to distinguish fetal and adult erythroid cells since its production closely follows the γ- to β-globin transition, but the molecular mechanism underlying transcriptional regulation of Car1 is unclear. Here, we show that Car1 mRNA decreases significantly when erythroid differentiation is induced in MEL cells. The Ldb1 protein complex including GATA1/SCL/LMO2 binds to the Car1 promoter in uninduced cells and reduced enrichment of the complex during differentiation correlates with loss of Car1 expression. Knockdown of Ldb1 results in a reduction of Ser2 phosphorylated RNA Pol II and Cdk9 at the Car1 promoter region, suggesting that Ldb1 is required for recruitment of Pol II as well as the transcription regulator P-TEFb to enhance elongation of Car1 transcripts. Taken together, these data show that Ldb1 forms a regulatory complex to maintain Car1 expression in erythroid cells. Expression analysis of induced and uninduced MEL cells after control or Ldb1 shRNA knockdown.
2012-12-11 | E-GEOD-42839 | biostudies-arrayexpress
Project description:The Ldb1/GATA-1/TAL1/LMO2 complex mediates long range interaction between the β-globin locus control region (LCR) and gene in adult mouse erythroid cells but whether this complex mediates chromatin interactions at other developmental stages or in human cells is unknown. We investigated human NLI (Ldb1 homologue) complex occupancy and chromatin conformation of the β-globin locus in human erythroid cells. In addition to the LCR, we find robust NLI complex occupancy at a site downstream of the Aγ-globin gene, within sequences of BGL3, an intergenic RNA transcript. In cells primarily transcribing β-globin, BGL3 is not transcribed and BGL3 sequences are occupied by NLI core complex members together with co-repressor ETO2 and γ-globin repressor BCL11A. The LCR and β-globin gene establish proximity in these cells. In contrast, when γ-globin transcription is re-activated by cytokines in these cells, ETO2 participation in the NLI complex at BGL3 is diminished, as is BCL11A occupancy, and both BGL3 and γ-globin are transcribed. In these cells, proximity between the BGL3/γ-globin region and the LCR is established. Thus, alternative NLI complexes mediate γ-globin transcription or silencing through long range LCR interactions involving an intergenic site of non-coding RNA transcription and ETO2 is critical to this process. ChIP-chip of GATA-1, NLI, and pol II in cell lines Comparison of GATA-1, NLI, and pol II binding on chromatin. 2 replicates for each protein; ChIP and input DNA for each replicate
2012-01-05 | E-GEOD-30047 | biostudies-arrayexpress
Project description:Carbonic anhydrase 1 (Car1), an early specific marker of the erythroid differentiation, has been used to distinguish fetal and adult erythroid cells since its production closely follows the γ- to β-globin transition, but the molecular mechanism underlying transcriptional regulation of Car1 is unclear. Here, we show that Car1 mRNA decreases significantly when erythroid differentiation is induced in MEL cells. The Ldb1 protein complex including GATA1/SCL/LMO2 binds to the Car1 promoter in uninduced cells and reduced enrichment of the complex during differentiation correlates with loss of Car1 expression. Knockdown of Ldb1 results in a reduction of Ser2 phosphorylated RNA Pol II and Cdk9 at the Car1 promoter region, suggesting that Ldb1 is required for recruitment of Pol II as well as the transcription regulator P-TEFb to enhance elongation of Car1 transcripts. Taken together, these data show that Ldb1 forms a regulatory complex to maintain Car1 expression in erythroid cells.
2012-12-11 | GSE42839 | GEO
Project description:The Ldb1/GATA-1/TAL1/LMO2 complex mediates long range interaction between the β-globin locus control region (LCR) and gene in adult mouse erythroid cells but whether this complex mediates chromatin interactions at other developmental stages or in human cells is unknown. We investigated human NLI (Ldb1 homologue) complex occupancy and chromatin conformation of the β-globin locus in human erythroid cells. In addition to the LCR, we find robust NLI complex occupancy at a site downstream of the Aγ-globin gene, within sequences of BGL3, an intergenic RNA transcript. In cells primarily transcribing β-globin, BGL3 is not transcribed and BGL3 sequences are occupied by NLI core complex members together with co-repressor ETO2 and γ-globin repressor BCL11A. The LCR and β-globin gene establish proximity in these cells. In contrast, when γ-globin transcription is re-activated by cytokines in these cells, ETO2 participation in the NLI complex at BGL3 is diminished, as is BCL11A occupancy, and both BGL3 and γ-globin are transcribed. In these cells, proximity between the BGL3/γ-globin region and the LCR is established. Thus, alternative NLI complexes mediate γ-globin transcription or silencing through long range LCR interactions involving an intergenic site of non-coding RNA transcription and ETO2 is critical to this process. ChIP-chip of GATA-1, NLI, and pol II in cell lines
2012-01-05 | GSE30047 | GEO
Project description:LMO2 is a component of multisubunit DNA-binding transcription factor complexes that regulate gene expression in hematopoietic stem and progenitor cell development. Enforced expression of LMO2 causes leukemia by inducing hematopoietic stem cell-like features in T-cell progenitor cells, but the biochemical mechanisms of LMO2 function have not been fully elucidated. In this study we systematically dissected the LMO2/LDB1 binding interface to investigate the role of this interaction in T-cell leukemia. Alanine scanning mutagenesis of the LIM interaction domain of LDB1 revealed a discrete motif R320LITR required for LMO2 binding. Most strikingly, co-expression of full length, wild type LDB1 increased LMO2 steady state abundance, whereas co-expression of mutant proteins deficient in LMO2 binding compromised LMO2 stability. These mutant LDB1 proteins also exerted dominant negative effects on growth and transcription in diverse leukemic cell lines. Raw gene expression data on HSB-2 cells is presented here. RNAseq were performed on HSB cell lines to examine their expression patterns
2015-12-15 | E-GEOD-75839 | biostudies-arrayexpress
Project description:LMO2 is a component of multisubunit DNA-binding transcription factor complexes that regulate gene expression in hematopoietic stem and progenitor cell development. Enforced expression of LMO2 causes leukemia by inducing hematopoietic stem cell-like features in T-cell progenitor cells, but the biochemical mechanisms of LMO2 function have not been fully elucidated. In this study we systematically dissected the LMO2/LDB1 binding interface to investigate the role of this interaction in T-cell leukemia. Alanine scanning mutagenesis of the LIM interaction domain of LDB1 revealed a discrete motif R320LITR required for LMO2 binding. Most strikingly, co-expression of full length, wild type LDB1 increased LMO2 steady state abundance, whereas co-expression of mutant proteins deficient in LMO2 binding compromised LMO2 stability. These mutant LDB1 proteins also exerted dominant negative effects on growth and transcription in diverse leukemic cell lines. Raw gene expression data on HSB-2 cells is presented here.
2015-12-15 | GSE75839 | GEO
Project description:The first site exhibiting hematopoietic activity in mammalian development is the yolk sac blood island, which originates from the hemangioblast. Here we performed differentiation assays, as well as genome-wide molecular and functional studies in BL-CFCs to gain insight into the function of the essential Ldb1 factor in early primitive hematopoietic development. We show that the previously reported lack of yolk sac hematopoiesis and vascular development in Ldb1-/- mouse result from a decreased number of hemangioblasts and a block in their ability to differentiate into erythroid and endothelial progenitor cells. Transcriptome analysis and correlation with the genome wide binding pattern of Ldb1 in hemangioblasts revealed a number of direct target genes and pathways misregulated in the absence of Ldb1. The regulation of essential developmental factors by Ldb1 defines it as an upstream transcriptional regulator of hematopoietic/endothelial development. We show the complex interplay that exists between transcription factors and signaling pathways during the very early stages of hematopoietic/endothelial development and the specific signalling occurring in hemangioblasts in contrast to more advanced hematopoietic developmental stages. Finally, by revealing novel genes and pathways, not previously associated with early development, our study provides novel candidate targets to manipulate the differentiation of hematopoietic and/or endothelial cells. Examination of endogenous Ldb1 genome-wide binding sites comparsion between ChIP and Control on Flk1+ BL-CFCs RNA was isolated from Ldb1+/+ and Ldb1-/- Flk1+ cells with the QIAGEN RNeasy Mini Kit and integrity was checked on the Agilent 2100 Bioanalyzer. RNA sequencing was performed on Illumina HiSeq 2000 platform according to the manufacturer instructions.
2013-02-09 | E-GEOD-43041 | biostudies-arrayexpress
Project description:How transcription factors (TFs) cooperate within large protein complexes to allow rapid modulation of gene expression during development is still largely unknown. Here we show that the key haematopoietic LIM-domain-binding protein-1 (LDB1) TF complex contains several activator and repressor components that together maintain an erythroid-specific gene expression programme primed for rapid activation until differentiation is induced. A combination of proteomics, functional genomics and in vivo studies presented here identifies known and novel co-repressors, most notably the ETO2 and IRF2BP2 proteins, involved in maintaining this primed state. The ETO2–IRF2BP2 axis, interacting with the NCOR1/SMRT co-repressor complex, suppresses the expression of the vast majority of archetypical erythroid genes and pathways until its decommissioning at the onset of terminal erythroid differentiation. Our experiments demonstrate that multimeric regulatory complexes feature a dynamic interplay between activating and repressing components that determines lineage-specific gene expression and cellular differentiation.
2015-11-19 | GSE59859 | GEO