title: A hierarchical order of factors in the generation of FLK1- and SCL-expressing hematopoietic and endothelial progenitors from embryonic stem cells.
abstract: The receptor tyrosine kinase FLK1 and the transcription factor SCL play crucial roles in the establishment of hematopoietic and endothelial cell lineages in mice. We have previously used an in vitro differentiation model of embryonic stem (ES) cells and demonstrated that hematopoietic and endothelial cells develop via sequentially generated FLK1(+) and SCL(+) cells. To gain a better understanding of cellular and molecular events leading to hematopoietic specification, we examined factors necessary for FLK1(+) and SCL(+) cell induction in serum-free conditions. We demonstrate that bone morphogenetic protein (BMP) 4 was required for the generation of FLK1(+) and SCL(+) cells, and that vascular endothelial growth factor (VEGF) was necessary for the expansion and differentiation of SCL-expressing hematopoietic progenitors. Consistently, Flk1-deficient ES cells responded to BMP4 and generated TER119(+) and CD31(+) cells, but they failed to expand in response to VEGF. The Smad1/5 and map kinase pathways were activated by BMP4 and VEGF, respectively. The overexpression of SMAD6 in ES cells resulted in a reduction of FLK1(+) cells. In addition, a MAP kinase kinase 1 specific inhibitor blocked the expansion of SCL(+) cells in response to VEGF. Finally, VEGF mediated expansion of hematopoietic and endothelial cell progenitors was inhibited by TGFbeta1, but was augmented by activin A. Our studies suggest that hematopoietic and endothelial commitment from the mesoderm occurs via BMP4-mediated signals and that expansion and/or differentiation of such progenitors is achieved by an interplay of VEGF, TGFbeta1 and activin A signaling.
authors.affiliation: Department of Pathology and Immunology, 660 South Euclid Avenue, Campus Box 8118, St Louis, MO 63110, USA.
authors.forename: Changwon
authors.initials: C
authors.lastname: Park
authors.forename: Iva
authors.initials: I
authors.lastname: Afrikanova
authors.forename: Yun Shin
authors.initials: YS
authors.lastname: Chung
authors.forename: Wen Jie
authors.initials: WJ
authors.lastname: Zhang
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Arentson
authors.forename: Guo hua
authors.initials: Gh
authors.lastname: Fong Gh
authors.forename: Alexander
authors.initials: A
authors.lastname: Rosendahl
authors.forename: Kyunghee
authors.initials: K
authors.lastname: Choi
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D002070:Butadienes / Q000494:pharmacology; D015704:CD4 Antigens / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000187:drug effects / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D048369:MAP Kinase Kinase 1; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D018995:Myosin Heavy Chains; D009570:Nitriles / Q000494:pharmacology; D024501:Nonmuscle Myosin Type IIB; D010750:Phosphoproteins / Q000187:drug effects / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051785:Smad Proteins; D051898:Smad1 Protein; D051902:Smad5 Protein; D051905:Smad6 Protein; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D015534:Trans-Activators / Q000187:drug effects / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D002070:Butadienes; D015704:CD4 Antigens; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D048369:MAP Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D018995:Myosin Heavy Chains; D009570:Nitriles; D024501:Nonmuscle Myosin Type IIB; D010750:Phosphoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011518:Proto-Oncogene Proteins; D051785:Smad Proteins; D051898:Smad1 Protein; D051902:Smad5 Protein; D051905:Smad6 Protein; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D015534:Trans-Activators; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; C525809:BMP4 protein, human; C525810:Bmp4 protein, mouse; C497399:SMAD1 protein, human; C497797:SMAD5 protein, human; C497802:SMAD6 protein, human; C497401:Smad1 protein, mouse; C497798:Smad5 protein, mouse; C497803:Smad6 protein, mouse; C508960:TGFB1 protein, human; C489366:Tal1 protein, mouse; C508961:Tgfb1 protein, mouse; C113580:U 0126; C067143:TAL1 protein, human; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; C103815:nonmuscle myosin type IIB heavy chain