Gene expression profiling of the early-stage CD34+ differentiation process
ABSTRACT: To better understand the early events regulating lineage-specific hematopoietic differentiation, we analyzed the transcriptional profiles of CD34+ human hematopoietic stem and progenitor cells (HSPCs) subjected to differentiation stimulus. CD34+ cells were cultured for 12 and 40 hours in liquid cultures with supplemented media favoring myeloid or erythroid commitment. Serial analysis of gene expression (SAGE) was employed to generate four independent libraries. CD34+ Hematopoietic Stem Progenitor Cells with no differentiation stimulus were used as a control library.
Project description:To better understand the early events regulating lineage-specific hematopoietic differentiation, we analyzed the transcriptional profiles of CD34+ human hematopoietic stem and progenitor cells (HSPCs) subjected to differentiation stimulus. Overall design: CD34+ cells were cultured for 12 and 40 hours in liquid cultures with supplemented media favoring myeloid or erythroid commitment. Serial analysis of gene expression (SAGE) was employed to generate four independent libraries. CD34+ Hematopoietic Stem Progenitor Cells with no differentiation stimulus were used as a control library.
Project description:Epigenetic mechanisms including histone modifications have emerged as important factors influencing cell fate determination. The functional role of H3K4 methylation, however, remains largely unclear in the maintenance and differentiation of hematopoietic stem/progenitor cells (HSC/HPCs). Here we show that DPY30, a shared core subunit of the SET1/MLL family methyltransferase complexes and a facilitator of their H3K4 methylation activity, is important for ex vivo proliferation and differentiation of human CD34+ HPCs. DPY30 promotes HPC proliferation by directly regulating the expression of genes critical for cell proliferation. Interestingly, while DPY30 knockdown (KD) in HPCs impaired their differentiation into the myelomonocytic lineage, it potently promoted hemoglobin production and affected the kinetics of their differentiation into the erythroid lineage. In an in vivo model, we show that morpholino-mediated dpy30 KD resulted in severe defects in the development of the zebrafish hematopoietic system, which could be partially rescued by co-injection of dpy30 mRNA. Taken together, our results establish a critical role of DPY30 in the proliferation and appropriate differentiation of hematopoietic progenitor cells as well as in animal hematopoiesis. Finally, we also demonstrate a crucial role of DPY30 in the growth of several MLL1-fusion-mediated leukemia cell lines. Total RNAs from control (scr) or knockdown (hD2, hD5) cells before and after culturing under condition promoting myelomonocytic differentiation were subjected to Illumina microarray analyses.
Project description:Hemopoiesis entails a series of hierarchically organized events that proceed throughout cell specification and terminates with cell differentiation. Commitment needs the transcription factors effort that, in concert with microRNAs, drives cell fate specification, answering to promiscuous patterns of gene expression by turning on lineage-specific genes and repressing alternate lineage transcripts. Therefore microRNAs and mRNAs cooperate to direct cell fate decisions. We obtained microRNAs profiles from human CD34+ hemopoietic progenitor cells and in-vitro differentiated erythroblasts, megakaryoblasts, monoblasts and myeloblasts precursors and we analyzed them together with the gene expression profiles of the same populations. We found that for most part of microRNAs specifically up-regulated in one single cell progeny an inverse correlation between microRNAs and down-regulated putative targets expression levels occurs. We chose hsa-mir-299-5p as a model to get further insights into the possible biological relevance of this microRNAs-mRNAs expression integrated analytical approach and we asked if the forced expression of a single lineage-specific microRNA is able to control the cell fate of CD34+ progenitors grown in multilineage culture conditions. Gain and loss of-function experiments established that mir-299-5p regulates hemopoietic progenitors fate modulating reciprocally megakaryocytic-granulocytic versus erythroid-monocytic differentiation and has at least two genuine targets, the transcription factors CTCF and SOX4. CD34+ hematopoietic progenitor cells were transfected with the Amaxa Nucleofector Device, using the Human CD34 Cell Nucleofection Kit, accordingly to the manufacturer’s instructions (Amaxa Biosystem, Cologne, Germany), and 5µg of either the Pre-miR miRNA Precursor Molecule—Negative Control # 1 (NC1) or the hsa-mir-299-5p Pre-miR miRNA Precursor Molecule (299-5p) (Ambion, Austin, TX, USA) and pulsed with the program U-008. The dataset is composed of three independent paired experiment of 299-5p gain of-function (three hsa-299-5p Pre-miR miRNA Precursor Molecule nucleoporated samples and three paired Pre-miR miRNA Precursor Molecule—Negative Control # 1 transfected ones).
Project description:Knockdown of HCLS1 mRNA in CD34+ hematopoietic cells resulted in a severe diminished in vitro myeloid differentiation which was in line with downregulation of a set of genes, e.g., of Wnt or PI3K/Akt signaling cascades. We performed microarrays to evaluate specific genes and signaling systems regulated by HCLS1 in hematopoietic cells. CD34+ hematopoietic cells were isolated from the bone marrow of healthy individuals, transduced with lenitvirus-based RFP-expressed shRNA constructs targeting HCLS1 mRNA (two different shRNA constructs were used simultaneously) or scrambled control shRNA. After 4 days of the transductions, RFP+ cells were sorted, and total RNA of sorted cells was isolated and used for Affymetrix Exome arrays.
Project description:The c-Myb transcription factor is highly expressed in immature hematopoietic cells and down-regulated during differentiation. To define the role of c-Myb in human hematopoietic lineage commitment, we studied the effects of its silencing during the commitment of human CD34+ Hematopoietic stem/progenitor cells. In CD34+ cells c-Myb silencing determined a cell cycle arrest in G0/G1 phase which strongly decreased the clonogenic efficiency, togheter with a reduction of erythroid colonies coupled with an increase of the macrophage and megakaryocyte ones. Moreover, morphological and flow cytometry data supported the preferential macrophage and megakaryocyte differentiation of c-Myb-silenced CD34+ cells. Taken together our data indicate that c-Myb is essential for the commitment along the erythroid and granulocyte lineages but not for the macrophage and megakaryocyte differentiation. Gene expression profiling of c-Myb-silenced CD34+ cells identified some potential c-Myb targets which can account for these effects, to study by Chromatin Immunoprecipitation and Luciferase Reporter Assay. To maximize siRNA transfection efficiency, we utilized the NucleofectorTM technology (Amaxa). CD34+ cells were transfected with a mixture of 3 siRNAs targeting c-Myb mRNA and with a non-targeting siRNA as a negative control. The expression level of c-Myb protein on control cells (MOCK and negative control treated cells) and MYBsiRNA treated cells was assessed by Western Blot at 24 and 48h post-nucleofection.
Project description:Histone deacetylase (HDAC) inhibitors are widely utilized in hematopoietic malignance therapy; nevertheless, little is currently known concerning their effects on normal myelopoiesis. In order to investigate a putative interference of HDAC inhibitors in myeloid commitment of hematopoietic stem/progenitor cells (HSPCs) we treated CD34+ cells with valproic acid (VPA). Moreover, we investigate changes in gene expression induced by VPA treatment on HSPCs, by means of microarray analysis in VPA treated and untreated (CTR) CD34+ cells. VPA treatment induced H4 histone acetylation in CD34+ cells and blocked them in G0-G1 phase of cell cycle. CD34 expression is maintained for a longer time in VPA treated cells, while the physiological decrease of CD34 antigen occurred in CTR cells. Moreover, VPA favored erythrocyte and megakaryocyte differentiation at the expense of granulocyte and mono-macrophage lineages, as demonstrated by immunophenotyping, morphological and clonogenic analysis. Finally, we demonstrated that VPA up-regulated master gene regulators of erythrocyte and megakaryocyte differentiation (GFI1B and MLLT3) through histone iper-acetylation of their promoters. These results indicate that VPA treatment enhances erythrocyte and megakaryocyte differentiation at the expense of granulocyte and mono-macrophage one. Microarray data provide for the first time a detailed molecular support for the biological effects promoted by VPA treatment in HSPCs. Human CD34+ cells were purified from umbilical Cord Blood (CB) samples. After an initial 24 hours of incubation, CD34+ cells were exposed to VPA. Total cellular RNA was extracted from untreated (CTR) and VPA treated CD34+ HSCs after 48 hours of treatment.
Project description:Although regulation of stem cell homeostasis by miRNAs is well studied, it is unclear how individual miRNAs, genomically encoded within an organized polycistron, can interact to induce an integrated phenotype. miR-99a/100, let-7 and miR-125b paralogues are encoded in two tricistrons on human chromosome 11 and 21. They are highly expressed in hematopoietic stem cells (HSCs) and acute megakaryoblastic leukemia (AMKL), an aggressive form of leukemia with poor prognosis. Integrative analysis of global gene expression profiling, miRNA target prediction and pathway architecture revealed that miR-99a/100, let-7 and miR-125b functionally converge at the combinatorial block of the TGFβ pathway by targeting four receptor subunits and two SMAD signaling transducers. In addition, downregulation of tumor suppressor genes APC/APC2 stabilizes active β-Catenin and enhances Wnt signaling. By switching the balance between Wnt and TGFβ signaling the concerted action of these tricistronic miRNAs promoted sustained expansion of murine and human HSCs in vitro or in vivo, while favoring megakaryocytic differentiation. We lentivirally transduced cord blood CD34+-hematopoietic stem and progenitor cells (CB-HSPCs) to ectopically express miR-125b-2, miR-99a, let-7c or miR-99a~125b-2 and cultured them in megakaryocytic differentiation medium for 7 days.
Project description:Expression data from CD34+ hematopoietic cells transduced with control or anti-SLPI shRNA, serum starved and treated with G-CSF. CD34+ hematopoietic cells were isolated from the bone marrow of healthy individuals, transduced with lenitvirus-based RFP-expressed shRNA constructs targeting SLPI mRNA or scrambled control shRNA. After 3 days of the transductions, RFP+ cells were sorted, serum starved for 24 hours and treated with G-CSF 10 ng/ml for 18 hours. Total RNA of sorted cells was isolated and used for Affymetrix Exome arrays.
Project description:Analysis of gene signatures in WT+Ctrl vs WT+ETV6-RUNX1, Btg1-/- and Btg1-/-+ETV6-RUNX1 in cKit+Ter119- fetal liver-derived hematopoietic progenitor cells (FL-HPCs). The Btg1-/-+ETV6-RUNX1 FL-HPCs display a strong increase in proliferation compared to WT+ETV6-RUNX1. Total RNA otained from WT+Ctrl, WT+ETV6-RUNX1, Btg1-/-+Ctrl and Btg1-/-+ETV6-RUNX1 FL-HPCs cells that were cultured for 12 days in expansion medium.
Project description:Transient leukemia (TL) is evident in 5-10% of all neonates with Down syndrome (DS) and associated with N-terminal truncating GATA1-mutations (GATA1s). Here we analyzed the effect of on gene expression upon ectopic expression of Gata1s or Gata1, while simultaneously knocking down endogenous GATA1, in wild-type CD34+-hematopoietic stem and progenitor cells during myeloid differentiation. Ectopic expression of Gata1s, but not Gata1, in wild-type CD34+-hematopoietic stem and progenitor cells induced hyperproliferation of eosinophil promyelocytes in vitro. While GATA1s retained the function of GATA1 to induce eosinophil genes by occupying their promoter regions, GATA1s was impaired in its ability to repress oncogenic MYC and the pro-proliferative E2F transcription network. We lentivirally transduced wild-type CD34+-hematopoietic stem and progenitor cells to ectopically express Gata1s or Gata1, while simultaneously knocking down endogenous GATA1, and cultured them in myeloid differentiation for 0, 4 and 14 days.