scholarly journals The scl +18/19 Stem Cell Enhancer Is Not Required for Hematopoiesis: Identification of a 5′ Bifunctional Hematopoietic-Endothelial Enhancer Bound by Fli-1 and Elf-1

2004 ◽  
Vol 24 (5) ◽  
pp. 1870-1883 ◽  
Author(s):  
Berthold Göttgens ◽  
Cyril Broccardo ◽  
Maria-Jose Sanchez ◽  
Sophie Deveaux ◽  
George Murphy ◽  
...  
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Transcription Factor ◽  
Cell Formation ◽  
Regulatory Elements ◽  
General Strategy ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Stem ◽  
Ets Family ◽  
Endothelial Development

ABSTRACT Analysis of cis-regulatory elements is central to understanding the genomic program for development. The scl/tal-1 transcription factor is essential for lineage commitment to blood cell formation and previous studies identified an scl enhancer (the +18/19 element) which was sufficient to target the vast majority of hematopoietic stem cells, together with hematopoietic progenitors and endothelium. Moreover, expression of scl under control of the +18/19 enhancer rescued blood progenitor formation in scl−/− embryos. However, here we demonstrate by using a knockout approach that, within the endogenous scl locus, the +18/19 enhancer is not necessary for the initiation of scl transcription or for the formation of hematopoietic cells. These results led to the identification of a bifunctional 5′ enhancer (−3.8 element), which targets expression to hematopoietic progenitors and endothelium, contains conserved critical Ets sites, and is bound by Ets family transcription factors, including Fli-1 and Elf-1. These data demonstrate that two geographically distinct but functionally related enhancers regulate scl transcription in hematopoietic progenitors and endothelial cells and suggest that enhancers with dual hematopoietic-endothelial activity may represent a general strategy for regulating blood and endothelial development.

Mouse Jagged2 is differentially expressed in hematopoietic progenitors and endothelial cells and promotes the survival and proliferation of hematopoietic progenitors by direct cell-to-cell contact

Blood ◽  
2000 ◽  
Vol 96 (3) ◽  
pp. 950-957 ◽  
Author(s):  
Schickwann Tsai ◽  
Jutta Fero ◽  
Steve Bartelmez
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Hematopoietic Stem Cells ◽  
Full Length ◽  
Differentially Expressed ◽  
Cell Contact ◽  
Proliferative Potential ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Stem ◽  
Direct Cell

To study the regulation of the early stages of hematopoiesis, cDNA representational difference analysis was used to isolate genes that were differentially expressed in primitive hematopoietic progenitors. The reasoning was that such genes were more likely to provide functions important to hematopoietic stem cells and progenitors. One of the genes identified through this approach encodes mouse Jagged2(mJagged2). Using quantitative reverse transcription–polymerase chain reaction, it was shown that mJagged2 was differentially expressed in c-kit+ hematopoietic progenitors, including those with the phenotypes of Lin− c-kit+Rhlo Holo and Lin−c-kit+ Rhhi Holo, and that they have been shown to be highly enriched for long-term and short-term repopulating hematopoietic stem cells, respectively. Western blot analyses showed that endothelial cells also expressed high levels of Jagged2, but stromal fibroblasts did not. Using a coculture system we found that exogenous, full-length mJagged2 promoted the survival and proliferation of hematopoietic progenitors, including the high-proliferative potential colony-forming cells. Direct cell-to-cell contact was required for this effect. Taken together, these findings indicate that both c-kit+ hematopoietic progenitors and endothelial cells express Jagged2 and that exogenous, full-length Jagged2 promotes the survival and proliferation of hematopoietic progenitors.

scholarly journals Deciphering Molecular Control of VEGFR2 Regulation in Hematopoietic Progenitors: GATA1-Mediated Repression of VEGFR2 Promotes Optimum Erythropoiesis

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1172-1172
Author(s):  
Avishek Ganguly ◽  
Omar S. Aljitawi ◽  
Soumen Paul
Keyword(s):  
Stem Cells ◽  
Molecular Mechanisms ◽  
Fetal Liver ◽  
Embryonic Stem ◽  
Erythroid Differentiation ◽  
Hematopoietic Progenitors ◽  
Erythroid Progenitors ◽  
Hematopoietic Stem ◽  
Molecular Control ◽  
Endothelial Development

Abstract VEGFR2 (also known as Flk1) is expressed in hemetopoietic precursors and is essential for both hematopoietic and vascular development. Interestingly, development of differentiated hematopoietic cell from hematopoietic stem cells (HSCs) is associated with VEGFR2 repression, whereas VEGFR2 expression is maintained throughout endothelial development. This differential regulation of VEGFR2 has been implicated as a key step to successfully branch out hematopoietic vs. endothelial development. However, molecular mechanisms that regulate transcriptionally active vs. repressive Vegfr2 chromatin domains in hematopoietic stem/progenitor cells (HSPCs) vs. differentiated hematopoietic cells are incompletely understood. Here, we report that transcription factor GATA1, a master-regulator of erythroid differentiation, is essential to repress VEGFR2 expression in erythroid progenitors. Genetic complementation analysis demonstrated that VEGFR2 expression in maintained in GATA1-null erythroid progenitors and rescue of GATA1-function induces VEGFR2 repression. Mechanistic studies in primary hematopoietic progenitors from mouse fetal liver and differentiating mouse embryonic stem cells (ESCs) identified a repressor element at the (-)88 kb region of the Vegfr2 locus from which GATA1 represses Vegfr2 transcription in erythroid progenitors. Furthermore, CRISPR/Cas9-mediated deletion of the Vegfr2(-)88 kb region results in reduced erythroid differentiation during fetal liver hematopoiesis. These results indicate that GATA1-mediated repression of VEGFR2 could be a determinant of optimum erythropoiesis. Disclosures No relevant conflicts of interest to declare.

Mouse Jagged2 is differentially expressed in hematopoietic progenitors and endothelial cells and promotes the survival and proliferation of hematopoietic progenitors by direct cell-to-cell contact

Blood ◽  
2000 ◽  
Vol 96 (3) ◽  
pp. 950-957 ◽  
Author(s):  
Schickwann Tsai ◽  
Jutta Fero ◽  
Steve Bartelmez
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Hematopoietic Stem Cells ◽  
Full Length ◽  
Differentially Expressed ◽  
Cell Contact ◽  
Proliferative Potential ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Stem ◽  
Direct Cell

Abstract To study the regulation of the early stages of hematopoiesis, cDNA representational difference analysis was used to isolate genes that were differentially expressed in primitive hematopoietic progenitors. The reasoning was that such genes were more likely to provide functions important to hematopoietic stem cells and progenitors. One of the genes identified through this approach encodes mouse Jagged2(mJagged2). Using quantitative reverse transcription–polymerase chain reaction, it was shown that mJagged2 was differentially expressed in c-kit+ hematopoietic progenitors, including those with the phenotypes of Lin− c-kit+Rhlo Holo and Lin−c-kit+ Rhhi Holo, and that they have been shown to be highly enriched for long-term and short-term repopulating hematopoietic stem cells, respectively. Western blot analyses showed that endothelial cells also expressed high levels of Jagged2, but stromal fibroblasts did not. Using a coculture system we found that exogenous, full-length mJagged2 promoted the survival and proliferation of hematopoietic progenitors, including the high-proliferative potential colony-forming cells. Direct cell-to-cell contact was required for this effect. Taken together, these findings indicate that both c-kit+ hematopoietic progenitors and endothelial cells express Jagged2 and that exogenous, full-length Jagged2 promotes the survival and proliferation of hematopoietic progenitors.

Generation of Hematopoietic Stem Cells from Purified Embryonic Endothelial Cells by a Simple and Efficient Strategy

2013 ◽  
Vol 40 (11) ◽  
pp. 557-563 ◽  
Author(s):  
Zhuan Li ◽  
Fan Zhou ◽  
Dongbo Chen ◽  
Wenyan He ◽  
Yanli Ni ◽  
...  
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Hematopoietic Stem Cells ◽  
Hematopoietic Stem ◽  
Efficient Strategy

Live imaging of Runx1 expression in the dorsal aorta tracks the emergence of blood progenitors from endothelial cells

Blood ◽  
2010 ◽  
Vol 116 (6) ◽  
pp. 909-914 ◽  
Author(s):  
Enid Yi Ni Lam ◽  
Christopher J. Hall ◽  
Philip S. Crosier ◽  
Kathryn E. Crosier ◽  
Maria Vega Flores
Keyword(s):  
Endothelial Cells ◽  
Transcription Factor ◽  
Fluorescent Protein ◽  
Living Organism ◽  
Time Lapse ◽  
Dorsal Aorta ◽  
Transgenic Zebrafish ◽  
Hematopoietic Stem ◽  
Green Fluorescent

Abstract Blood cells of an adult vertebrate are continuously generated by hematopoietic stem cells (HSCs) that originate during embryonic life within the aorta-gonad-mesonephros region. There is now compelling in vivo evidence that HSCs are generated from aortic endothelial cells and that this process is critically regulated by the transcription factor Runx1. By time-lapse microscopy of Runx1-enhanced green fluorescent protein transgenic zebrafish embryos, we were able to capture a subset of cells within the ventral endothelium of the dorsal aorta, as they acquire hemogenic properties and directly emerge as presumptive HSCs. These nascent hematopoietic cells assume a rounded morphology, transiently occupy the subaortic space, and eventually enter the circulation via the caudal vein. Cell tracing showed that these cells subsequently populated the sites of definitive hematopoiesis (thymus and kidney), consistent with an HSC identity. HSC numbers depended on activity of the transcription factor Runx1, on blood flow, and on proper development of the dorsal aorta (features in common with mammals). This study captures the earliest events of the transition of endothelial cells to a hemogenic endothelium and demonstrates that embryonic hematopoietic progenitors directly differentiate from endothelial cells within a living organism.

scholarly journals Synergistic interactions between interleukin-11 and interleukin-4 in support of proliferation of primitive hematopoietic progenitors of mice

Blood ◽  
1991 ◽  
Vol 78 (6) ◽  
pp. 1448-1451 ◽  
Author(s):  
M Musashi ◽  
SC Clark ◽  
T Sudo ◽  
DL Urdal ◽  
M Ogawa
Keyword(s):  
Stem Cells ◽  
Colony Formation ◽  
Interleukin 4 ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Stem ◽  
Synergistic Interactions ◽  
Two Factors ◽  
Stromal Cell Line ◽  
Interleukin 11

Abstract Interleukin-11 (IL-11) is a newly identified lymphohematopoietic cytokine originally derived from the primate bone marrow stromal cell line, PU-34. Separately, we reported that IL-11 augments IL-3-dependent proliferation of primitive murine hematopoietic progenitors in culture. We have now examined the synergistic interactions between IL-11 and IL- 4 in support of colony formation from marrow cells of mice treated 2 days before with 150 mg/kg 5-fluorouracil. Neither recombinant human IL- 11 nor murine IL-4 alone was effective in the support of colony formation. When the two factors were combined, there was major enhancement of colony formation, including that of multilineage colony- forming cells. Serial observations (mapping studies) of development of multipotential blast cell colonies indicated that the synergy between IL-11 and IL-4 is due in part to shortening of the dormant period of the stem cells, an effect very similar to that of IL-6 and granulocyte colony-stimulating factor. The combination of IL-11 and IL-4 may be useful in the stimulation of dormant hematopoietic stem cells in vivo.

scholarly journals A Novel, Myeloid Transcription Factor, C/EBPε, Is Upregulated During Granulocytic, But Not Monocytic, Differentiation

Blood ◽  
1997 ◽  
Vol 90 (7) ◽  
pp. 2591-2600 ◽  
Author(s):  
Roberta Morosetti ◽  
Dorothy J. Park ◽  
Alexey M. Chumakov ◽  
Isabelle Grillier ◽  
Masaaki Shiohara ◽  
...  
Keyword(s):  
Stem Cells ◽  
Transcription Factor ◽  
Hematopoietic Stem Cells ◽  
Cell Line ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Leukemia Cell ◽  
Rt Pcr ◽  
Hematopoietic Stem ◽  
Nb4 Cells

Human C/EBPε is a newly cloned CCAAT/enhancer-binding transcription factor. Initial studies indicated it may be an important regulator of human myelopoiesis. To elucidate the range of expression of C/EBPε, we used reverse transcription-polymerase chain reaction (RT-PCR) analysis and examined its expression in 28 hematopoietic and 14 nonhematopoietic cell lines, 16 fresh myeloid leukemia samples, and normal human hematopoietic stem cells and their mature progeny. Prominent expression of C/EBPε mRNA occurred in the late myeloblastic and promyelocytic cell lines (NB4, HL60, GFD8), the myelomonoblastic cell lines (U937 and THP-1), the early myeloblast cell lines (ML1, KCL22, MDS92), and the T-cell lymphoblastic leukemia cell lines CEM and HSB-2. For the acute promyelocytic leukemia cell line NB4, C/EBPε was the only C/EBP family member that was easily detected by RT-PCR. No C/EBPε mRNA was found in erythroid, megakaryocyte, basophil, B lymphoid, or nonhematopoietic cell lines. Most acute myeloid leukemia samples (11 of 12) from patients expressed C/EBPε. Northern blot and RT-PCR analyses showed that C/EBPε mRNA decreased when the HL60 and KG-1 myeloblast cell lines were induced to differentiate toward macrophages. Similarly, Western blot analysis showed that expression of C/EBPε protein was either unchanged or decreased slightly as the promyelocytic cell line NB4 differentiated down the macrophage-like pathway after treatment with a potent vitamin D3 analog (KH1060). In contrast, C/EBPε protein levels increased dramatically as NB4 cells were induced to differentiate down the granulocytic pathway after exposure to 9-cis retinoic acid. Furthermore, very early, normal hematopoietic stem cells (CD34+/CD38−), purified from humans had very weak expression of C/EBPε mRNA, but levels increased as these cells differentiated towards granulocytes. Likewise, purified granulocytes appeared to express higher levels of C/EBPε mRNA than purified macrophages. Addition of phosphothiolated antisense, but not sense oligonucleotides to C/EBPε, decreased clonal growth of HL-60 and NB4 cells by about 50% compared with control cultures. Taken together, our results indicate that expression of C/EBPε is restricted to hematopoietic tissues, especially myeloid cells as they differentiate towards granulocytes and inhibition of its expression in HL-60 and NB4 myeloblasts and promyelocytes decreased their proliferative capacity. Therefore, this transcriptional factor may play an important role in the process of normal myeloid development.

scholarly journals Gata2 is required for HSC generation and survival

2013 ◽  
Vol 210 (13) ◽  
pp. 2843-2850 ◽  
Author(s):  
Emma de Pater ◽  
Polynikis Kaimakis ◽  
Chris S. Vink ◽  
Tomomasa Yokomizo ◽  
Tomoko Yamada-Inagawa ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Transcription Factor ◽  
Developmental Stages ◽  
Vascular Endothelial ◽  
Vascular Integrity ◽  
Hematopoietic Stem ◽  
Vascular Endothelial Cadherin ◽  
Umbilical Arteries ◽  
Specific Deletion

Knowledge of the key transcription factors that drive hematopoietic stem cell (HSC) generation is of particular importance for current hematopoietic regenerative approaches and reprogramming strategies. Whereas GATA2 has long been implicated as a hematopoietic transcription factor and its dysregulated expression is associated with human immunodeficiency syndromes and vascular integrity, it is as yet unknown how GATA2 functions in the generation of HSCs. HSCs are generated from endothelial cells of the major embryonic vasculature (aorta, vitelline, and umbilical arteries) and are found in intra-aortic hematopoietic clusters. In this study, we find that GATA2 function is essential for the generation of HSCs during the stage of endothelial-to-hematopoietic cell transition. Specific deletion of Gata2 in Vec (Vascular Endothelial Cadherin)-expressing endothelial cells results in a deficiency of long-term repopulating HSCs and intra-aortic cluster cells. By specific deletion of Gata2 in Vav-expressing hematopoietic cells (after HSC generation), we further show that GATA2 is essential for HSC survival. This is in contrast to the known activity of the RUNX1 transcription factor, which functions only in the generation of HSCs, and highlights the unique requirement for GATA2 function in HSCs throughout all developmental stages.

scholarly journals Scl isoforms act downstream of etsrp to specify angioblasts and definitive hematopoietic stem cells

Blood ◽  
2010 ◽  
Vol 115 (26) ◽  
pp. 5338-5346 ◽  
Author(s):  
Xi Ren ◽  
Gustavo A. Gomez ◽  
Bo Zhang ◽  
Shuo Lin
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Vascular Endothelial ◽  
Hematopoietic Stem ◽  
Vegf Signaling ◽  
Endothelial Growth Factor ◽  
Endothelial Development ◽  
Definitive Hematopoiesis ◽  
Runx1 Expression

Abstract Recent lineage studies suggest that hematopoietic stem cells (HSCs) may be derived from endothelial cells. However, the genetic hierarchy governing the emergence of HSCs remains elusive. We report here that zebrafish ets1-related protein (etsrp), which is essential for vascular endothelial development, also plays a critical role in the initiation of definitive hematopoiesis by controlling the expression of 2 stem cell leukemia (scl) isoforms (scl-α and scl-β) in angioblasts. In etsrp morphants, which are deficient in endothelial and HSC development, scl-α alone partially rescues angioblast specification, arterial-venous differentiation, and the expression of HSC markers, runx1 and c-myb, whereas scl-β requires angioblast rescue by fli1a to restore runx1 expression. Interestingly, when vascular endothelial growth factor (Vegf) signaling is inhibited, HSC marker expression can still be restored by scl-α in etsrp morphants, whereas the rescue of arterial ephrinb2a expression is blocked. Furthermore, both scl isoforms partially rescue runx1 but not ephrinb2a expression in embryos deficient in Vegf signaling. Our data suggest that downstream of etsrp, scl-α and fli1a specify the angioblasts, whereas scl-β further initiates HSC specification from this angioblast population, and that Vegf signaling acts upstream of scl-β during definitive hematopoiesis.

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