Project description:EKLF is a Krüppel-like transcription factor identified as a transcriptional activator and chromatin modifier in erythroid cells. EKLF-deficient (Eklf -/-) mice die at day 14.5 of gestation from severe anemia. In this study, we demonstrate that early progenitor cells fail to undergo terminal erythroid differention in Eklf -/- embryos. To discover potential EKLF target genes responsible for the failure of erythropoiesis, transcriptional profiling was performed with RNA from wild type and Eklf -/- early erythroid progenitor cells. These analyses identified significant perturbation of a network of genes involved in cell cycle regulation, with the critical regulator of the cell cycle, E2f2, at a hub. E2f2 mRNA and protein levels were markedly decreased in Eklf -/- early erythroid progenitor cells, which showed a delay in the G1-to-S-phase transition. Chromatin immunoprecipitation analysis demonstrated EKLF occupancy at the proximal E2f2 promoter in vivo. Consistent with the role of EKLF as a chromatin modifier, EKLF binding-sites in the E2f2 promoter were located in a region of EKLF-dependent DNase I sensitivity in early erythroid progenitor cells. We propose a model in which EKLF-dependent activation and modification of the E2f2 locus is required for cell cycle progression preceding terminal erythroid differentiation. RNA was isolated from flow-sorted early erythroid progenitors in 13.5 day old fetal livers from EKLF knock out mice (n=3 fetal livers) and wild-type control mice (n=3 fetal livers) for gene expression analysis
Project description:EKLF is a Krüppel-like transcription factor identified as a transcriptional activator and chromatin modifier in erythroid cells. EKLF-deficient (Eklf -/-) mice die at day 14.5 of gestation from severe anemia. In this study, we demonstrate that early progenitor cells fail to undergo terminal erythroid differention in Eklf -/- embryos. To discover potential EKLF target genes responsible for the failure of erythropoiesis, transcriptional profiling was performed with RNA from wild type and Eklf -/- early erythroid progenitor cells. These analyses identified significant perturbation of a network of genes involved in cell cycle regulation, with the critical regulator of the cell cycle, E2f2, at a hub. E2f2 mRNA and protein levels were markedly decreased in Eklf -/- early erythroid progenitor cells, which showed a delay in the G1-to-S-phase transition. Chromatin immunoprecipitation analysis demonstrated EKLF occupancy at the proximal E2f2 promoter in vivo. Consistent with the role of EKLF as a chromatin modifier, EKLF binding-sites in the E2f2 promoter were located in a region of EKLF-dependent DNase I sensitivity in early erythroid progenitor cells. We propose a model in which EKLF-dependent activation and modification of the E2f2 locus is required for cell cycle progression preceding terminal erythroid differentiation.
Project description:EKLF/Klf1 is a Zinc-finger transcription activator essential for erythroid lineage commitment and terminal differentiation. Using ChIP-Seq, we investigate EKLF DNA binding and transcription activation mechanisms during mouse embryonic erythropoiesis. Our study focuses on global EKLF binding dynamics during embryonic erythropoiesis in primary WT and Nan/+ mouse fetal liver, and its correlation with chromatin accessibility, CBP occupancy, histone acetylation, and finally its effect on RNA Polymerase II pausing and elongation. Our goal is to elucidate the mechanisms of transcription activation by EKLF/Klf1 during embryonic erythropoiesis in vivo and in the context of RNA pol II pause-release control. Additionally, we aim to understand the unusually severe effects of conservative E to D change in Nan-EKLF and the molecular mechanisms leading to dominant anemia through global gene dysregulation.
Project description:The erythroid Krüppel-like factor EKLF/KLF1 is a hematopoietic transcription factor binding to CACCC DNA motif and participating in the regulation of erythroid differentiation. With combined use of microarray-based gene expression profiling and promoter-based ChIP-chip assay of E14.5 fetal liver cells from wild type (WT) and EKLF-knockout (Eklf-/-) mouse embryos, we have identified the pathways and direct target genes activated or repressed by EKLF. This genome-wide study together with molecular/ cellular analysis of mouse erythroleukemic cells (MEL) indicate that among the downstream direct target genes of EKLF is Tal1/Scl. Tal1/Scl encodes another DNA-binding hematopoietic transcription factor TAL1/SCL known to be an Eklf activator and essential for definitive erythroid differentiation. Further identification of the authentic Tall gene promoter in combination with in vivo genomic footprinting approach and DNA reporter assay demonstrate that EKLF activates Tall gene through binding to a specific CACCC motif located in its promoter. These data establish the existence of a previously unknow positive regulatory feedback loop between two DNA-binding hematopoietic transcription factors that sustains the mammalian erythropoiesis.
Project description:The erythroid Krüppel-like factor EKLF/KLF1 is a hematopoietic transcription factor binding to CACCC DNA motif and participating in the regulation of erythroid differentiation. With combined use of microarray-based gene expression profiling and promoter-based ChIP-chip assay of E14.5 fetal liver cells from wild type (WT) and EKLF-knockout (Eklf-/-) mouse embryos, we have identified the pathways and direct target genes activated or repressed by EKLF. This genome-wide study together with molecular/ cellular analysis of mouse erythroleukemic cells (MEL) indicate that among the downstream direct target genes of EKLF is Tal1/Scl. Tal1/Scl encodes another DNA-binding hematopoietic transcription factor TAL1/SCL known to be an Eklf activator and essential for definitive erythroid differentiation. Further identification of the authentic Tall gene promoter in combination with in vivo genomic footprinting approach and DNA reporter assay demonstrate that EKLF activates Tall gene through binding to a specific CACCC motif located in its promoter. These data establish the existence of a previously unknow positive regulatory feedback loop between two DNA-binding hematopoietic transcription factors that sustains the mammalian erythropoiesis.
Project description:The transcription factor GATA-1, EKLF and NF-E2 promotes erythroid differentition by regulating their target genes, however, the intricate interplays between these key TFs and microRNA genes are largely unknown. Chromatin immunoprecipitation (ChIP) of GATA-1, EKLF and NF-E2 together with microRNA genomic promoter profiling by ChIP-on-chip analysis demonstrated that GATA-1, EKLF and NF-E2 collaborately regulate a series of microRNA genes. Comparison of microRNA promoter arrays of GATA-1 VS EKLF VS NF-E2 in K562 cells suffering with hemin induced erythroid differentiation
Project description:KLF1 (EKLF) regulates a diverse suite of genes to direct erythroid cell differentiation from bi-potent progenitors. To determine the local cis-regulatory contexts and transcription factor networks in which KLF1 operates, we performed KLF1 ChIP-seq in the mouse. We found at least 945 sites in the genome of E14.5 fetal liver erythroid cells which are occupied by endogenous KLF1. Many of these recovered sites reside in erythroid gene promoters such as β-globin, but the majority are distant to any known gene. Our data suggests KLF1 directly regulates most aspects of terminal erythroid differentiation including production of α and β-globin protein chains, heme biosynthesis, co-ordination of proliferation and anti-apoptotic pathways, and construction of the red cell membrane and cytoskeleton by functioning primarily as a transcriptional activator. Additionally, we suggest new mechanisms for KLF1 co-operation with other transcription factors, in particular the erythroid transcription factor GATA1, to maintain homeostasis in the erythroid compartment. Examination of KLF1 occupancy in primary erythroid cells. KLF1-ChIP and input samples were run on AB SOLiD Systems 2.0 and 3.0. The genomic alignment files (*sorted.txt) and peak file (*bed) contain the combined System 2.0 and 3.0 data.