MRNA profiles of four developmentally related hematopoietic cell types (LSK, L-S-K+, Gr1+ and Ter119+) isolated from the BM of B6 and D2 mice
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ABSTRACT: The combination of valproic acid and lithium delays hematopoietic stem\progenitor differentiation Microarray-based microRNA profiling study was peformed of four developmentally related hematopoietic cell types isolated from the BM of B6 and D2 mice. Total RNA isolated from purified LSK multilineage cells, committed LS−K+ cells, erythroid TER-119+ cells and myeloid Gr-1+ cells was hybridized to Single Color Illumina mouse WG-6_V2 mRNA arrays. Triplicates were generated for each of the 8 conditions (4 cell types, 2 mouse strains).
Project description:performed a genetic screen for microRNAs that are differentially expressed between LSK, LS−K+, erythroid and myeloid cells isolated from C57BL/6 and DBA/2 mice. This analysis identified 131 microRNAs that were differentially expressed between cell types and 15 that were differentially expressed between mouse strains. Of special interest was an evolutionary conserved miR-cluster located on chromosome 17 consisting of miR-99b, let-7e and miR-125a. All cluster members were most highly expressed in LSKs and down-regulated upon differentiation. In addition, these microRNAs were higher expressed in DBA/2 cells compared to C57BL/6 cells, and thus correlated with HSPC frequency. To functionally characterize these microRNAs, we overexpressed the entire miR-cluster 99b/let-7e/125a and miR-125a alone in BM cells from C57BL/6 mice. Overexpression of the miR-cluster or miR-125a dramatically increased day-35 CAFC activity and caused severe hematopoietic phenotypes upon transplantation. We showed that a single member of the miR-cluster, namely miR-125a, is responsible for the majority of the observed miR-cluster overexpression effects. Finally, we performed genome-wide gene expression arrays and identified candidate target genes through which miR-125a may modulate HSPC fate. Microarray-based microRNA profiling study was peformed of four developmentally related hematopoietic cell types isolated from the BM of B6 and D2 mice. Total RNA isolated from purified LSK multilineage cells, committed LS−K+ cells, erythroid TER-119+ cells and myeloid Gr-1+ cells was hybridized to Agilent microRNA arrays. Triplicates were generated for each of the 8 conditions (4 cell types, 2 mouse strains). From the final anaysis one replicate for B6 LS-K+ cells was removed based on PCA, therefore B6 Prog group consist of only 2 biological replicates.
Project description:Expression profiles of 7-day cultured HSPCs in the presence or absence of valproic acid and/or lithium. Two small molecules, valproic acid (VPA) and lithium (Li), were tested to inhibit differentiation of hematopoietic stem/progenitor (HSPC) cells in culture. HSPCs exposed to VPA and Li during differentiation-inducing culture preserved an immature cell phenotype, provided radioprotection to lethally irradiated recipients and enhanced in vivo repopulating potential. Furthermore, VPA and Li synergistically preserved expression of stem cell-related genes and repressed genes involved in differentiation. Target genes were collectively co-regulated during normal hematopoietic differentiation. Additionally, transcription factor networks were identified as possible primary regulators. Our results demonstrate that the combination of VPA and Li potently prevents differentiation at the biological and the molecular level, and provide evidence to suggest that combinatorial screening of chemical compounds may uncover possible additive/synergistic effects to modulate stem cell fate decisions. These data consist of total mRNA obtained from hematopoietic cells cultured for 7 days in the presence or absence of valproic acid and/or lithium. All samples were analyzed in independent biological triplicates.
Project description:Two small molecules, valproic acid (VPA) and lithium (Li), were tested to inhibit differentiation of hematopoietic stem/progenitor (HSPC) cells in culture. HSPCs exposed to VPA and Li during differentiation-inducing culture preserved an immature cell phenotype, provided radioprotection to lethally irradiated recipients and enhanced in vivo repopulating potential. Furthermore, VPA and Li synergistically preserved expression of stem cell-related genes and repressed genes involved in differentiation. Target genes were collectively co-regulated during normal hematopoietic differentiation. Additionally, transcription factor networks were identified as possible primary regulators. Our results demonstrate that the combination of VPA and Li potently prevents differentiation at the biological and the molecular level, and provide evidence to suggest that combinatorial screening of chemical compounds may uncover possible additive/synergistic effects to modulate stem cell fate decisions. These data consist of total mRNA obtained from hematopoietic cells cultured for 7 days in the presence or absence of valproic acid and/or lithium. All samples were analyzed in independent biological triplicates.
Project description:We demonstrate that Msi2 is the predominant form expressed in hematopoietic stem cells (HSC), and its knockdown leads to reduced engraftment and depletion of HSCs in vivo. Overexpression of Msi2 in a mouse model increases HSC cell cycle progression and cooperates with BCR-ABL1 to induce an aggressive leukemia. MSI2 is over-expressed in human myeloid leukemia, and expression levels directly correlate with decreased patient survival, thereby defining MSI2 expression as a novel prognostic marker in acute myeloid leukemia (AML). Depletion of MSI2 in human myeloid leukemia cells leads to decreased proliferation and apoptosis. These data implicate the MSI2 RNA binding protein in myeloid leukemogenesis and identify a novel potential target for therapy in AML. Mouse hematopoietic stem cells (defined as LineageLow, Sca1+, Kit+; LSK; n=3) as well as committed progenitor cells (LineageLow, Sca1-, Kit+; LK; n=3) were sorted and RNA was extracted using Qiagen RNeasy Micro Kit according to manufacturers instruction. cDNA was fragmented and biotinylated before hybridization onto Affymetrix Mouse Expression Array 430 2.0.
Project description:Ezh2 is a protein member of PRC2 and has described like a functional repressor gene. We are investigating the role of Ezh2 in hematopoietic stem cell, aging and leukemia. In the present study, we generated mouse models that allow gain-of-function of Ezh2 in the hematopoietic system. Activation of Ezh2 expression specifically in self-renewing HSCs alters gene expression programs and severely compromises hematopoietic function, leading to the development of myeloproliferative disease.
Project description:Generation of abundant engraftable hematopoietic cells from autologous tissues promises new therapies for hematologic diseases. Differentiation of pluripotent stem cells into hematopoietic cells results in emergence of cells that have poor engraftment potential. To circumvent this hurdle, we have devised a vascular niche model to phenocopy the developmental microenvironment of hemogenic cells thereby enabling direct transcriptional reprogramming of human endothelial cells (ECs) into hematopoietic cells. In this approach, transduction of human umbilical vein ECs (HUVECs) or adult human dermal microvascular ECs (hDMECs) with transcription factors (TFs), FOSB, GFI1, RUNX1, and SPI1 (FGRS) and induction with a instructive vascular niche feeder layer in a xenobiotic- and serum-free microenvironment results in generation of long-term engraftable hematopoietic multilineage progenitors (rEC-HMLPs). The rEC-HMLPs had robust proliferative and multilineage colony forming units (CFU) potential, including granulocytic/monocytic, megakaryocytic, erythroid and lymphoid lineages. When transplanted, hDMEC-derived rEC-HMLPs were capable of long-term multilineage primary and secondary hematopoietic engraftment. A subset of engrafted rEC-HMLPs phenotypically and functionally resembled cord blood cells. By conditionally expressing the FGRS TFs, we further optimized reprogramming of ECs into rEC-HMLPs manifesting features of self-renewing multi-potent progenitor populations (MPPs). Our approach replicates critical aspects of hematopoietic development and essential role of vascular niche induction in orchestrating hematopoietic specification and may prove useful for engineering autologous engraftable hematopoietic cells for treatment of inherited and acquired blood disorders. . Transcriptome sequencing of rEC-HMLPs, hDMECs, HUVECs and other cell types
Project description:Ezh2 is a protein member of PRC2 and has described like a functional repressor gene. We are investigating the role of Ezh2 in hematopoietic stem cell, aging and leukemia. In the present study, we generated mouse models that allow gain-of-function of Ezh2 in the hematopoietic system. Activation of Ezh2 expression specifically in self-renewing HSCs alters gene expression programs and severely compromises hematopoietic function, leading to the development of myeloproliferative disease. We used microarrays to detail the global programme of gene expression in LSK that has relationship with the overexpression of Ezh2. LSK were marked and isolated by Fluorescence-activated cell sorting in Trizol.
Project description:performed a genetic screen for microRNAs that are differentially expressed between LSK, LS−K+, erythroid and myeloid cells isolated from C57BL/6 and DBA/2 mice. This analysis identified 131 microRNAs that were differentially expressed between cell types and 15 that were differentially expressed between mouse strains. Of special interest was an evolutionary conserved miR-cluster located on chromosome 17 consisting of miR-99b, let-7e and miR-125a. All cluster members were most highly expressed in LSKs and down-regulated upon differentiation. In addition, these microRNAs were higher expressed in DBA/2 cells compared to C57BL/6 cells, and thus correlated with HSPC frequency. To functionally characterize these microRNAs, we overexpressed the entire miR-cluster 99b/let-7e/125a and miR-125a alone in BM cells from C57BL/6 mice. Overexpression of the miR-cluster or miR-125a dramatically increased day-35 CAFC activity and caused severe hematopoietic phenotypes upon transplantation. We showed that a single member of the miR-cluster, namely miR-125a, is responsible for the majority of the observed miR-cluster overexpression effects. Finally, we performed genome-wide gene expression arrays and identified candidate target genes through which miR-125a may modulate HSPC fate.
Project description:A hallmark of adult hematopoiesis is the continuous replacement of blood cells with limited lifespans. While active hematopoietic stem cell (HSC) contribution to multilineage hematopoiesis is the foundation of clinical HSC transplantation, recent reports have questioned the physiological contribution of HSCs to normal/steady-state adult hematopoiesis. Here, we use inducible lineage tracing from genetically marked adult HSCs and reveal robust HSC-derived multilineage hematopoiesis. This commences via defined progenitor cells, but varies substantially in between different hematopoietic lineages. By contrast, adult HSC contribution to hematopoietic cells with proposed fetal origins is neglible. Finally, we establish that the HSC contribution to multilineage hematopoiesis declines with increasing age. Therefore, while HSCs are active contributors to native adult hematopoiesis, it appears that the numerical increase of HSCs is a physiologically relevant compensatory mechanism to account for their reduced differentiation capacity with age