A network including TGFβ/Smad4, Gata2 and p57 regulates proliferation of mouse hematopoietic stem/progenitor cells [ChIP-seq]
ABSTRACT: Transforming growth factor-β (TGFβ) is a potent inhibitor of hematopoietic stem cell (HSC) proliferation. However, the precise mechanism for this effect is unknown. Here, we have identified the transcription factor Gata2, previously described as an important regulator of HSC function, as an early and direct target gene for TGFβ-induced Smad signaling in hematopoietic stem and progenitor cells (HSPCs). Interestingly, TGFβ-induced Gata2 upregulation is critical for subsequent transcriptional activation of the TGFβ signaling effector molecule p57 and resulting growth arrest of HSPCs. Importantly, both Gata2 and p57 are abundantly expressed in freshly isolated highly purified HSCs, demonstrating the relevance of this circuit in HSC regulation within the HSC niche. Our results connect key molecules involved in HSC self-renewal and reveal a functionally relevant network regulating proliferation of primitive hematopoietic cells. To identify TGFβ targets downstream of Gata2, we carried out a ChIP-Seq experiment on TGFβ-induced Lhx2 cells. Interestingly, there was a large overlap between the GATA2-bound genes and genes differentially expressed after 2h TGFβ induction. One sample of 1x10^8 cells (treated with 10 ng/ml TGFβ for 2h) was sequenced.
Project description:Transforming growth factor-β (TGFβ) is a potent inhibitor of hematopoietic stem cell (HSC) proliferation. However, the precise mechanism for this effect is unknown. Here, we have identified the transcription factor Gata2, previously described as an important regulator of HSC function, as an early and direct target gene for TGFβ-induced Smad signaling in hematopoietic stem and progenitor cells (HSPCs). Interestingly, TGFβ-induced Gata2 upregulation is critical for subsequent transcriptional activation of the TGFβ signaling effector molecule p57 and resulting growth arrest of HSPCs. Importantly, both Gata2 and p57 are abundantly expressed in freshly isolated highly purified HSCs, demonstrating the relevance of this circuit in HSC regulation within the HSC niche. Our results connect key molecules involved in HSC self-renewal and reveal a functionally relevant network regulating proliferation of primitive hematopoietic cells. To identify early gene targets of TGFβ signaling in hematopoietic progenitor cells, we performed high-throughput gene expression profiling of a primitive murine hematopoietic cell line. One of the revealed target genes was the transcription factor Gata2, which became the base for the rest of the study. Three independent RNA harvests were separately analyzed. Untreated cells were used as controls to the 10ng/ml TGFb-treated cells.
Project description:The Gata2 transcription factor is a pivotal regulator of hematopoietic stem cell (HSC) development and maintenance. Gata2 functions in the embryo during endothelial cell to hematopoietic cell transition (EHT) to affect hematopoietic cluster, HPC and HSC formation. Although previous studies of cell populations phenotypically enriched in HPCs and HSCs show expression of Gata2, there has been no direct study of Gata2 expressing cells during normal hematopoiesis. In this study we generate a Gata2 Venus reporter mouse model with unperturbed Gata2 expression to examine the hematopoietic function and transcriptome of Gata2 expressing and nonexpressing cells. Gata2Venus- HPCs 1 replicate, Gata2Venus+ HPCs 1 replicate
Project description:Erg is an ETS family transcription factor frequently overexpressed in human leukemias and has been implicated as a key regulator of hematopoietic stem cells (HSCs). However how Erg controls normal hematopoiesis, particularly at the stem cell level, remains poorly understood. Using homologous recombination, we generated an Erg knockdown allele (Ergkd) in which Erg expression can be restored upon Cre-mediated excision of a Stopper cassette. In Ergkd/+ mice, ~40% reduction in Erg dosage perturbed both fetal liver and bone marrow hematopoiesis by reducing the numbers of Lin-Sca-1+c-Kit+ (LSK) hematopoietic stem and progenitor cells (HSPCs) and megakaryocytic progenitors. By genetic mosaic analysis, we found Erg-restored HSPCs outcompeted Ergkd/+ HSPCs for contributing to adult hematopoiesis in vivo. Intriguingly, HSC differentiation also appeared attenuated, leading to accumulation of long-term HSCs in the mutant LSK population. Accordingly, microarray analysis of Erg-restored and Ergkd/+ HSPCs from the same animal revealed enrichment of stem cell-related pathways in Ergkd/+ HSPCs. Overall, reduced Erg dosage perturbs hematopoiesis by reducing HSC numbers and impairing HSC differentiation, possibly via two Erg targets, Jun and Myc. Overall design: Erg-restored (to wild type) YFP+ HSPCs and Erg-knockdown (~40% reduction) YFP- HSPCs were sorted from the same mouse [Mx1Cre;Ergkd/+;Rosa26-Stop-YFP (R26Y)]; RNA was prepared from the sorted HSPCs, amplified by Nugen V2 and applied to Affymetrix mouse genome 430 2.0 arrays.
Project description:The derivation of functional, transplantable HSCs from an pluripotent stem cells in vitro holds great promise for clinical therapies, but is unachieved. In order to achieve full functionality of HSCs, it is vital to determine the extent to which PSCs can currently be differentiated to the HSC program in vitro and identify the remaining dysregulated genetic pathways. Microarrays were used to compare the transcritomes of ESC-derived immunophenotypic HSPCs to endogenous HSPCs from various stages of development to determine the programs important for human HSC development and function, and which programs were lacking in ESC-derived hematopoietic cells. CD34+CD38-CD43+CD90+ HSPCs were sorted from human placenta and embryoid bodies, and CD34+CD38-CD45+CD90+ HSPCs sorted from fetal liver and embryoid bodies co-cultured on OP9-M2 stroma, the RNA was extracted, library created and hybridized to the Affymetrix microarray
Project description:Epigenetic regulation serves as the basis for stem cell differentiation into distinct cell types, but it is unclear how global epigenetic changes are regulated during this process. Here, we tested the hypothesis that global chromatin organization affects the lineage potential of stem cells and that manipulation of chromatin dynamics influences stem cell function. Using nuclease sensitivity assays, we found a progressive decrease in chromatin digestion between pluripotent embryonic stem cells (ESCs), multipotent hematopoietic stem and progenitor cells (HSPCs), and mature hematopoietic cells. Quantification of chromatin composition by high-resolution microscopy revealed that ESCs contain significantly more euchromatin than HSPCs, with a further reduction in euchromatin as HSPCs transition into mature cells. Increased cellular maturation also led to heterochromatin localization to the nuclear periphery. Functionally, prevention of heterochromatin formation by inhibition of the histone methyltransferase G9a resulted in delayed hematopoietic stem cell (HSC) differentiation. Our results demonstrate significant global rearrangements of chromatin structure during embryonic and adult stem cell differentiation, and that heterochromatin formation by H3K9 methylation is an important regulator of HSC differentiation. Overall design: Examination of gene expression profile of in vitro cultured mouse HSC with the G9a inhibitor UNC0638
Project description:We used ChIP-Seq to map Ldb1, Scl and Gata2 binding sites in mouse hematopoietic progenitor cells (HPCs). Together with functional studies using conventional and conditional Ldb1 deficient mouse models and bioinformatics analysis, we systematically determined a transcriptional program controlled by Ldb1 complexes in HSC maintenance. Overall design: To evaluate the role of Ldb1 in hematopoietic stem cell maintenance.
Project description:GATA2 is a transcription factor that is required for hematopoietic stem cell (HSC) differentiation. GATA2 is also expressed in mesenchymal cells and blocks differentiation of both white and brown adipocytes by interfering with C/EBP activity and PPARγ expression. By studying genome-wide binding sites of endogenous GATA2 in mesenchymal stem cells (MSC), we discovered a previously unrecognized function of GATA2 in the regulation of skeletal development-related genes. In contrast to hematopoietic stem cells, canonical GATA2 binding motifs in MSCs co-localized with motifs for transcription factors of the FOX and HOX family, known regulators of skeletal development. Consistently, ectopic GATA2 expression in MSCs regulated many osteoblast-related genes. Ectopic GATA2 blocked, whereas GATA2 deletion enhanced differentiation of osteoblastic precursors. GATA2 expression inhibited bone morphogenetic protein (BMP)-2 induced SMAD1/5/8 activity, a pathway that drives osteoblastogenesis. MSC-specific deletion of GATA2 in mice affected both numbers and osteogenic potential of bone-residing precursors without disturbing normal skeletal development. In adult mice, MSC-specific GATA2 deficiency affected trabecular bone structure and its mechanical properties. blood phenotype? In summary, our study identified GATA2 as a novel regulator of osteoblast differentiation and bone morphology, suggesting a role of GATA2 in MSC lineage determination that goes beyond adipocyte differentiation. Microarrays analysis was done to determine gene expression changes between sqWAW-MSC control cells and sqWAT-MSC cells with Gata2 over-expression. Overall design: This dataset consists of two sample groups: sqWAT-MSC cells infected with empty (control) or GATA2-expressing retroviruses (GATA2 over-expression). Each sample group consists of three replicates samples.
Project description:We used ChIP-Seq to map Ldb1, Scl and Gata2 binding sites in mouse hematopoietic progenitor cells (HPCs). Together with functional studies using conventional and conditional Ldb1 deficient mouse models and bioinformatics analysis, we systematically determined a transcriptional program controlled by Ldb1 complexes in HSC maintenance. To evaluate the role of Ldb1 in hematopoietic stem cell maintenance.
Project description:Combinatorial transcription factor (TF) interactions regulate hematopoietic stem cell formation, maintenance and differentiation, and are increasingly recognised as drivers of stem cell signatures in cancer. However, genome-wide combinatorial binding patterns for key regulators do not exist in primary human hematopoietic stem/progenitor cells (HSPCs) and have constrained analysis of the global architecture of the molecular circuits controlling these cells. Here we provide new high-resolution genome-wide binding maps of seven key TFs (FLI1, ERG, GATA2, RUNX1, SCL, LYL1 and LMO2) in human CD34+ HSPCs together with quantitative RNA and microRNA expression profiles. We catalogue binding of TFs at coding genes and microRNA promoters and report that combinatorial binding of all seven TFs is favoured and is associated with differential expression of genes and microRNA in HSPCs. We also uncover a hitherto unrecognized association between FLI1 and RUNX1 pairing in HSPCs, establish a correlation between the density of histone modifications, which mark active enhancers and the number of overlapping TFs at a peak and identify complex relationships between specific miRNAs and coding genes regulated by the heptad. Taken together, this study demonstrates that a heptad of TFs forms a dense auto-regulatory core in human HSPCs with binding of all seven TFs at tissue specific regulatory elements of heptad genes and collectively regulates miRNAs that in turn target components of the heptad and genes regulated by the heptad. Examination of cominatorial binding by 7 transcription factors, 1 IgG control along with mRNA and small RNA sequencing in human CD34+ cells