title: Putative intermediate precursor between hematogenic endothelial cells and blood cells in the developing embryo.
abstract: During embryogenesis, endothelial cells are a source of hematopoietic cells. Vascular endothelial (VE)-cadherin modulates adherens junctions between endothelial cells. How endothelial cells, integrated into the vascular bed via adherens junctions, give rise to free-floating hematopoietic cells has been examined. Contrary to our previous reports, in this report a cell type simultaneously expressing VE-cadherin and the hematopoietic marker CD45 was identified, without rigorous enzymatic dissociation of embryonic tissues. In spite of expressing several other endothelial markers such as endothelial cell nitrous oxide synthase (ECNOS) and MECA-32, this newly defined population failed to produce endothelial colonies when cultured on OP9 stroma, in direct contrast to enzymatically dissociated VE-cadherin+ cells. When isolated from 9.5 days post coitus (d.p.c.) embryos, VE-cadherin+ CD45+ cells generated erythroid, myeloid, but not B lymphoid, cells, also in contrast to VE-cadherin+ cells obtained by enzymatic dissociation. Runx1 null mutant embryos lacked this novel population. Collectively, these results introduce a novel VE-cadherin+ population within the developing embryo, which may represent an intermediate cell type in the transition of hemogenic endothelial cells into blood.
authors.affiliation: Department of Molecular Genetics, Faculty of Medicine and Graduate School of Medicine, Kyoto University, Shogoin Kawaharacho 53, Sakyo-ku, Japan. sfraser@mail.uni-mainz.de
authors.forename: Stuart T
authors.initials: ST
authors.lastname: Fraser
authors.forename: Minetaro
authors.initials: M
authors.lastname: Ogawa
authors.forename: Tomomasa
authors.initials: T
authors.lastname: Yokomizo
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ito
authors.forename: Satomi
authors.initials: S
authors.lastname: Nishikawa
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Nishikawa
mesh_terms: D000818:Animals; D015703:Antigens, CD; D015415:Biomarkers; D001773:Blood Cells / Q000502:physiology*; D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000196:embryology* / Q000502:physiology; D005260:Female; D017493:Leukocyte Common Antigens / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D009154:Mutation; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; D015820:Cadherins; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D017493:Leukocyte Common Antigens; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D000099152:Cadherin 5; C493726:Runx1 protein, mouse