Project description:RUNX1 (also known as AML1) is a key transcription factor for definitive hematopoietic stem cell development and following hematopoietic cell linage specifications, in which chromatin- or epigennome-mediated regulation by RUNX1, particularly regulation of DNA methylation status, is proposed to be involved in addition to its direct gene expression regulation. However, how RUNX1 regulates DNA methylation status and its role in the hematopoiesis remain to be elucidated. Here we first demonstrated that RUNX1 induces RUNX1 binding site directed DNA demethylation across the whole genome. HaloTag-based pull-down assay revealed associations of RUNX1 with active DNA demethylation related proteins such as TET, TDG or GADD45A, suggested that the RUNX1-mediated DNA demethylation is active DNA demethylation mechanism. Additional combinatorial overexpression of TET and TDG enlarged the RUNX1-mediated DNA demethylation, supporting what RUNX1-mediated DNA demethylation is active DNA demethylation. These results strongly suggested that RUNX1-mediated DNA demethylation is achieved by recruiting those proteins involved in active DNA demethylation. Finally, we found that the RUNX1-mediated demethylation predominately targets and activates hematopoietic genes whose promoter regions are demethylated during hematopoiesis. Collectively, our insight suggested that RUNX1-mediated binding site directed DNA demethylation is a novel mechanism of hematopoietic gene activation.
Project description:Background: DNA methylation is a fundamental epigenetic modification which is involved in many biological systems such as differentiation and disease. We and other groups recently discovered that a part of transcription factors (TFs) plays a role for site-specificity determination of DNA demethylation in a binding site-directed manner, although number of reports for such TFs are limited. Results: Here, we develop a screening system to identify TFs which induce the binding site-directed DNA methylation changes. The system consists of ectopic expression of target TFs in model cells and the DNA methylome analysis followed by overrepresentation analysis of the corresponding TF binding motif at differentially methylated regions. Our system successfully identifies binding site-directed demethylation of SPI1 which is known to promote DNA demethylation in a binding-site directed manner. We extend our screening system to 15 master TFs which are involved in cellular differentiations, and identified 8 (RUNX3, GATA2, CEBPB, MAFB, NR4A2, MYOD1, CEBPA and TBX5) novel binding site-directed DNA demethylation inducing TFs. Gene ontology and specifically expressing tissue enrichment analysis revealed that those 8 TFs demethylate genome regions which are associated with corresponding biological roles, supporting performance of our system. We also describe characteristics of the binding site-directed DNA demethylation induced by those TFs; targeting highly methylated CpGs, local DNA demethylation, and overlap of demethylated regions between same family TFs. Conclusion: Thus, our results emphasize usefulness of the developed screening system for identification of TFs which induce DNA demethylation in a site-directed manner.
Project description:During ontogeny the transcription factor RUNX1 governs the emergence of definitive hematopoietic cells from specialized endothelial cells, called hemogenic endothelium (HE). The ultimate consequence of this endothelial-to-hematopoietic transition is the concomitant activation of the hematopoietic program and down-regulation of the endothelial program. However, due to the rare and transient nature of the HE, little is known about the initial role of RUNX1 within this population. We therefore developed and implemented a highly sensitive DamID (DNA adenine methyltransferase identification) based methodology, including a novel data analysis pipeline, to map early RUNX1 transcriptional targets in HE cells. This novel transcription factor binding site identification protocol should be widely applicable to other low abundance cell types and factors. Integration of the RUNX1 binding profile with gene expression data revealed an unexpected early role for RUNX1 as a positive regulator of cell adhesion and migration associated genes within the HE. This suggests that RUNX1 orchestrates HE cell positioning and integration prior to the release of hematopoietic cells. Overall, our genome-wide analysis of the RUNX1 binding and transcriptional profile in the HE provides a novel comprehensive resource of target genes that will facilitate the precise dissection of the role of RUNX1 in early blood development. Runx1b binding profiles of mouse ES derived haemogenonic endothelium were generated by deep sequencing using the SOLiD 3 or 4 System (Applied Biosystems). Three biological duplicates and three technical replicates where sequenced for each of the following lines: iDam_runx1-/- (iDamko) and iRunx1b::Dam_runx1-/- (iRunx1b::Damko)
Project description:During ontogeny the transcription factor RUNX1 governs the emergence of definitive hematopoietic cells from specialized endothelial cells, called hemogenic endothelium (HE). The ultimate consequence of this endothelial-to-hematopoietic transition is the concomitant activation of the hematopoietic program and down-regulation of the endothelial program. However, due to the rare and transient nature of the HE, little is known about the initial role of RUNX1 within this population. We therefore developed and implemented a highly sensitive DamID (DNA adenine methyltransferase identification) based methodology, including a novel data analysis pipeline, to map early RUNX1 transcriptional targets in HE cells. This novel transcription factor binding site identification protocol should be widely applicable to other low abundance cell types and factors. Integration of the RUNX1 binding profile with gene expression data revealed an unexpected early role for RUNX1 as a positive regulator of cell adhesion and migration associated genes within the HE. This suggests that RUNX1 orchestrates HE cell positioning and integration prior to the release of hematopoietic cells. Overall, our genome-wide analysis of the RUNX1 binding and transcriptional profile in the HE provides a novel comprehensive resource of target genes that will facilitate the precise dissection of the role of RUNX1 in early blood development. mRNA profiles of mouse ES derived Haemogenonic Endothelium (cKit+ Tie2+ CD41-) were generated by deep sequencing using the SOLiD 5500XL Genetic Analyser (Applied Biosystems). Two biological duplicates of each of the following lines was sequenced: iDam & BryGFP (both wt background) and iDam_runx1-/- (iDamko) & Ainv18_runx1-/- (Ainv18ko). The latter two lines are Runx1 knockouts.
Project description:During ontogeny the transcription factor RUNX1 governs the emergence of definitive hematopoietic cells from specialized endothelial cells, called hemogenic endothelium (HE). The ultimate consequence of this endothelial-to-hematopoietic transition is the concomitant activation of the hematopoietic program and down-regulation of the endothelial program. However, due to the rare and transient nature of the HE, little is known about the initial role of RUNX1 within this population. We therefore developed and implemented a highly sensitive DamID (DNA adenine methyltransferase identification) based methodology, including a novel data analysis pipeline, to map early RUNX1 transcriptional targets in HE cells. This novel transcription factor binding site identification protocol should be widely applicable to other low abundance cell types and factors. Integration of the RUNX1 binding profile with gene expression data revealed an unexpected early role for RUNX1 as a positive regulator of cell adhesion and migration associated genes within the HE. This suggests that RUNX1 orchestrates HE cell positioning and integration prior to the release of hematopoietic cells. Overall, our genome-wide analysis of the RUNX1 binding and transcriptional profile in the HE provides a novel comprehensive resource of target genes that will facilitate the precise dissection of the role of RUNX1 in early blood development.
Project description:During ontogeny the transcription factor RUNX1 governs the emergence of definitive hematopoietic cells from specialized endothelial cells, called hemogenic endothelium (HE). The ultimate consequence of this endothelial-to-hematopoietic transition is the concomitant activation of the hematopoietic program and down-regulation of the endothelial program. However, due to the rare and transient nature of the HE, little is known about the initial role of RUNX1 within this population. We therefore developed and implemented a highly sensitive DamID (DNA adenine methyltransferase identification) based methodology, including a novel data analysis pipeline, to map early RUNX1 transcriptional targets in HE cells. This novel transcription factor binding site identification protocol should be widely applicable to other low abundance cell types and factors. Integration of the RUNX1 binding profile with gene expression data revealed an unexpected early role for RUNX1 as a positive regulator of cell adhesion and migration associated genes within the HE. This suggests that RUNX1 orchestrates HE cell positioning and integration prior to the release of hematopoietic cells. Overall, our genome-wide analysis of the RUNX1 binding and transcriptional profile in the HE provides a novel comprehensive resource of target genes that will facilitate the precise dissection of the role of RUNX1 in early blood development.
Project description:DNA methylation is a major epigenetic modification for gene silencing and is dramatically altered spatiotemporally during cellular development. However, the roles of DNA methylation dynamics and regulation in cellular development remain unclear. The present analyses of DNA methylome dynamics during hematopoietic development suggest that DNA demethylation pre-defines the gene expression potential of terminal differentiation-specific genes at the progenitor cell stage and is regulated by lineage-specific transcription factors (TFs). Demethylation of majority of hypo-methylated CpGs in terminally differentiated cells occurs during the progenitor cell stage and is associated with rapid upregulation of terminal differentiation-specific genes. Accordingly, TF overrepresentation analyses indicated that lineage-specific TFs regulate DNA demethylation. The present experiments show that RUNX1 induces site-directed active DNA demethylation by recruiting DNA demethylation enzymes. Collectively, the present data indicate an integrated system of DNA methylation and gene expression during cellular development.
Project description:DNA methylation is a major epigenetic modification for gene silencing and is dramatically altered spatiotemporally during cellular development. However, the roles of DNA methylation dynamics and regulation in cellular development remain unclear. The present analyses of DNA methylome dynamics during hematopoietic development suggest that DNA demethylation pre-defines the gene expression potential of terminal differentiation-specific genes at the progenitor cell stage and is regulated by lineage-specific transcription factors (TFs). Demethylation of majority of hypo-methylated CpGs in terminally differentiated cells occurs during the progenitor cell stage and is associated with rapid upregulation of terminal differentiation-specific genes. Accordingly, TF overrepresentation analyses indicated that lineage-specific TFs regulate DNA demethylation. The present experiments show that RUNX1 induces site-directed active DNA demethylation by recruiting DNA demethylation enzymes. Collectively, the present data indicate an integrated system of DNA methylation and gene expression during cellular development.
Project description:KDM1A-mediated H3K4 demethylation is a well-established mechanism underlying transcriptional gene repression, but its role in gene activation is less clear. Here we report a critical function and novel mechanism of action of KDM1A in glucocorticoid receptor (GR)-mediated gene transcription. Biochemical purification of the nuclear GR complex revealed KDM1A as an integral component. In cell-free assays, GR modulates KDM1A-catalyzed H3K4 progressive demethylation by limiting loss of H3K4me1. Similarly, in cells KDM1A binds to most GR binding sites where it removes preprogrammed H3K4me2 but leaves H3K4me1 untouched. Blocking KDM1A catalytic activity prevents H3K4me2 removal, severely impairs GR binding to chromatin, and dysregulates GR-targeted genes. Taken together, these data suggest KDM1A-mediated H3K4me2 demethylation at GRBSs promotes GR binding and plays an important role in glucocorticoid-induced gene transcription, offering a new mechanism contributing to nuclear receptor mediated gene activation.
Project description:In B cells infected by the cancer-associated Epstein-Barr virus (EBV), RUNX3 and RUNX1 transcription is manipulated to control cell growth. The EBV-encoded EBNA2 transcription factor (TF) activates RUNX3 transcription leading to RUNX3-mediated repression of the RUNX1 promoter and the relief of RUNX1-directed growth repression. We show that EBNA2 activates RUNX3 through a specific element within a -97 kb super-enhancer in a manner dependent on the expression of the Notch DNA-binding partner RBP-J. We also reveal that the EBV TFs EBNA3B and EBNA3C contribute to RUNX3 activation in EBV-infected cells by targeting the same element. Uncovering a counter-regulatory feed-forward step, we demonstrate EBNA2 activation of a RUNX1 super-enhancer (-139 to -250 kb) that results in low-level RUNX1 expression in cells refractory to RUNX1-mediated growth inhibition. EBNA2 activation of the RUNX1 super-enhancer is also dependent on RBP-J. Consistent with the context-dependent roles of EBNA3B and EBNA3C as activators or repressors, we find that these proteins negatively regulate the RUNX1 super-enhancer, curbing EBNA2 activation. Taken together our results reveal cell-type specific exploitation of RUNX gene super-enhancers by multiple EBV TFs via the Notch pathway to fine tune RUNX3 and RUNX1 expression and manipulate B-cell growth.