Project description:We previously demonstrated that hematopoietic stem cell (HSC)-like cells are robustly expanded from mouse embryonic stem (ES) cells by enforced expression of Lhx2, a LIM-homeobox domain (LIM-HD) transcription factor. Here we established an ES cell line which conditionally expressed Lhx2 by Tet-On system. The ES cells were differentiated into HSC-like cells by Lhx2 expression. Lhx2-regulated genes were identified by comparing the HSC-like cells with those cultured in the absence of Lhx2 expression.
Project description:We previously demonstrated that hematopoietic stem cell (HSC)-like cells are robustly expanded from mouse embryonic stem (ES) cells by enforced expression of Lhx2, a LIM-homeobox domain (LIM-HD) transcription factor. Here we established an ES cell line which conditionally expressed Lhx2 by Tet-On system. The ES cells were differentiated into HSC-like cells by Lhx2 expression. Lhx2-regulated genes were identified by comparing the HSC-like cells with those cultured in the absence of Lhx2 expression. Mouse ES with inducible Lhx2 were differentiated on OP9 stromal cells into hematopoietic lineage. On day 5 of the differentiation induction,Lhx2 expression was started by the addition of doxycycline (dox) and the cells were cultured on OP9 stromal cells in the presence of IL-6 and SCF. On day 20, HSC-like cells were harvested and re-seeded onto OP9 stromal cells in the absence of Lhx2 expression by dox-removal for 3 days. these cells were compared with the original HSC-like cells.
Project description:This is a mathematical model describing the hematopoietic lineages with leukemia lineages, as controlled by end-product negative feedback inhibition. Variables include hematopoietic stem cells, progenitor cells, terminally differentiated HSCs, leukemia stem cells, and terminally differentiated leukemia stem cells.
Project description:Lhx2 is a LIM-homeobox transcription factor which could induce hematopoietic stem cell-like cells from mouse embryonic stem cells and induced pluripotent stem cells. However, the effects of Lhx2 overexpression in the human chronic myeloid leukemia cell line K562 remains unknown. Therefore we carried out Lhx2 overexpression in K562 cells.
Project description:Expression of the lim-homeodomain transcription factor is required for sustained maintenance of heamatopoietic stem cell like cells in undifferentiated form durng in vitro culturing. Cell lines were created from the mouse embryonic stem (ES) cell line, Ainv15. The gene Lhx2 was introducted into these cells under the control of a tetracycline-responsive element. In the presence of tetracycline (or its analogue doxycycline), these cells express Lhx2. In DoxHPC7 GFP is co-expressed together with the Lhx2 gene. We used these cells to carry out a time-course study where the effects of Lhx2 withdrawal were studied.
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 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:Sin3a is the central scaffold protein of the prototypical Hdac1/2 chromatin repressor complex, crucially required during early embryonic development for the growth of pluripotent cells of the inner cell mass. Here, we explore the endogenous composition of the Sin3a-Hdac complex in pluripotent embryonic stem (ES) and differentiated cells. To do this, we established an endogenous double immunoprecipitation strategy coupled with quantitative mass spectrometry (ENDIP-MS) allowing us to define the precise composition of the Sin3a complex in multiple cell types. We identify the Fam60a subunit as a key defining feature of a variant Sin3a complex present in ES cells, but not in differentiated cells. Fam60a co-occupies H3K4me3 positive promoters with Sin3a and is essential to maintain it on chromatin. Consistent with this, Fam60a depletion phenocopies the loss of Sin3a, leading to decreased proliferation, an extended G1-phase and the deregulation of genes associated with differentiation. Taken together, our data characterise Fam60a as an essential core subunit of a variant Sin3a complex in ES cells required to promote rapid proliferation and to prevent unscheduled differentiation.
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 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.
Project description:Previously, we reported that the transcription factor Mesp1 promotes the cell fates of cardiomyocytes, smooth muscle, and vascular endothelium. Recently, hematopoietic stem cells (HSCs) were shown to derive from hemogenic endothelium. Since Mesp1 regulates development of endothelium, it potentially could influence gene expression related to hematopoietic development. Our present fate mapping study found that Mesp1-cre efficiently labeled hematopoietic lineages in vivo. This result suggested that Mesp1 might be expressed in progenitors of the hematopoietic system, such as hemogenic endothelium. To test this, we purified Flk1+ Tie2+ endothelium derived from differentiating ES cells with or without Mesp1 induction, and used microarray expression analysis to identify genes strongly up-regulated by Mesp1. Embryonic stem (ES) cells harboring a doxycycline (dox)-inducible Mesp1 gene (A2lox.Mesp1) were differentiated as embryoid bodies for 5 days in the absence (-) or presence (+) of dox from day 2 to day 4. Flk1+Tie2+ endothelial cells were purified by cell sorting for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Low-C was performed upon human cord-blood long-term hematopoietic stem cells (LT-HSC) and short-term hematopoietic stem cells (ST-HSC). This was used to demonstrate that chromatin conformation changes associated with LT-HSC activation are enriched in ST-HSC.