title: Stimulation of vasculogenesis and leukopoiesis of embryonic stem cells by extracellular transfer RNA and ribosomal RNA.
abstract: OBJECTIVE
  Cell injury releases nucleic acids supporting inflammation and stem cell activation. Here, the impact of extracellular ribonucleic acid, especially transfer RNA (ex-tRNA), on vasculogenesis and leukopoiesis of mouse embryonic stem (ES) cells was investigated.
  
  
  RESULTS
  ex-tRNA, whole cell RNA and ribosomal RNA (ex-rRNA) but not DNA increased CD31-positive vascular structures in embryoid bodies. Ex-tRNA and ex-rRNA increased numbers of VEGFR2(+), CD31(+) and VE-cadherin(+) vascular cells as well as CD18(+), CD45(+) and CD68(+) cells, indicating leukocyte/macrophage differentiation. This was paralleled by mRNA and protein expression of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor-165 (VEGF165) and neuropilin 1 (NRP1), phosphorylation of phosphatidyl inositol 3-kinase (PI3K) and VEGF receptor 2 (VEGFR2) as well as mRNA expression of α-smooth muscle actin (α-SMA). ex-tRNA was taken up by endosomes, increased expression of the pro-angiogenic semaphorin B4 receptor plexin B1 as well as the ephrin-type B receptor 4 (EphB4) and ephrinB2 ligand and enhanced cell migration, which was inhibited by the VEGFR2 antagonist SU5614 and the PI3K inhibitor LY294002. This likewise abolished the effects of ex-tRNA on vasculogenesis and leukopoiesis of ES cells. Ex-tRNA increased NOX1, NOX2, NOX4 and DUOX2 mRNA and boosted the generation of superoxide and hydrogen peroxide which was inhibited by radical scavengers, the NADPH oxidase inhibitors apocynin, VAS2870, ML171, and plumbagin as well as shRNA silencing of NOX1 and NOX4.
  
  
  CONCLUSIONS
  Our findings indicate that ex-tRNA treatment induces vasculogenesis and leukopoiesis of ES cells via superoxide/hydrogen peroxide generated by NADPH oxidase and activation of VEGFR2 and PI3K.
authors.affiliation: Department of Physiology, Medical School, Justus Liebig University, Giessen, Germany.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Sharifpanah
authors.affiliation: Department of Physiology, Medical School, Justus Liebig University, Giessen, Germany.
authors.forename: Sepali
authors.initials: S
authors.lastname: De Silva
authors.affiliation: Clinic of Internal Medicine I, Cardiology Division, Friedrich Schiller University, Jena, Germany; Department of Zoology, Faculty of Science, Tanta University, Tanta, Egypt.
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Bekhite
authors.affiliation: Department of Biochemistry, Medical School, Justus Liebig University, Giessen, Germany.
authors.forename: Jorge
authors.initials: J
authors.lastname: Hurtado-Oliveros
authors.affiliation: Center for Sepsis Control and Care, Jena University Hospital, Jena, Germany.
authors.forename: Klaus T
authors.initials: KT
authors.lastname: Preissner
authors.affiliation: Clinic of Internal Medicine I, Cardiology Division, Friedrich Schiller University, Jena, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Wartenberg
authors.affiliation: Department of Physiology, Medical School, Justus Liebig University, Giessen, Germany. Electronic address: heinrich.sauer@physiologie.med.uni-giessen.de.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Sauer
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D002465:Cell Movement; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000378:metabolism / Q000473:pathology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007124:Immunoenzyme Techniques; D019891:Leukopoiesis / Q000235:genetics*; D051379:Mice; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000235:genetics*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics*; D012343:RNA, Transfer / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D042461:Vascular Endothelial Growth Factor A; D013481:Superoxides; D012343:RNA, Transfer; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: Angiogenesis; Embryonic stem cells; Leukopoiesis; Reactive oxygen species (ROS); Vascular endothelial growth factor; Vasculogenesis