title: α2-Macroglobulin enhances vasculogenesis/angiogenesis of mouse embryonic stem cells by stimulation of nitric oxide generation and induction of fibroblast growth factor-2 expression.
abstract: α2-macroglobulin (α2M) is an acute-phase protein released upon challenges like cardiac hypertrophy and infarction. α2M signals via the low density lipoprotein receptor-related protein (LRP-1) and may induce stem cell activation. In the present study, the effects of α2M on vasculogenesis/angiogenesis and underlying signaling cascades were investigated in mouse embryonic stem (ES) cells. LRP-1 was expressed in ES cells and upregulated during differentiation. α2M dose dependently increased CD31-positive vascular structures in ES cell-derived embryoid bodies, the early cardiovascular markers isl-1, Nkx-2.5, and flk-1 as well as numbers of VE-cadherin and flk-1-positive cells, but downregulated α-smooth muscle actin. Enhancement of vasculogenesis/angiogenesis by α2M was abolished by the LRP-1 antagonist receptor-associated protein (RAP) and LRP-1 blocking antibody. Notably, α2M stimulated vascular growth in the chicken chorioallantois membrane assay, but not in a human umbilical vein endothelial cell spheroid model. α2M increased fibroblast growth factor-2 (FGF-2) protein expression, which was abolished by RAP, induced nitric oxide (NO) generation as determined by 4,5-diaminofluorescein diacetate microfluorometry, and activated nitric oxide synthase-3 (NOS-3) as well as extracellular-regulated kinase 1,2 (ERK1/2) and phosphatidyl inositol 3-kinase (PI3K). NO generation, the increase in FGF-2 expression, and the stimulation of vasculogenesis/angiogenesis by α2M were blunted by the NO synthase inhibitor L-NAME, the ERK1/2 inhibitor PD98059, and the PI3K inhibitor LY294002. Furthermore, vasculogenesis/angiogenesis by α2M was inhibited in the presence of the FGF receptor 1 antagonist SU5402. In conclusion, α2M stimulates endothelial and early cardiac, but not smooth muscle differentiation of ES cells through generation of NO, activation of ERK1/2 as well as PI3K, and induction of FGF-2 expression.
authors: Department of Physiology, Justus Liebig University Giessen, Giessen, Germany. heinrich.sauer@physiologie.med.uni-giessen.de
authors: Heinrich
authors: H
authors: Sauer
authors: Febina
authors: F
authors: Ravindran
authors: Matthias
authors: M
authors: Beldoch
authors: Fatemeh
authors: F
authors: Sharifpanah
authors: Jamila
authors: J
authors: Jedelská
authors: Boris
authors: B
authors: Strehlow
authors: Maria
authors: M
authors: Wartenberg
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D002642:Chick Embryo; D058732:Embryoid Bodies / Q000502:physiology*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D051379:Mice; D057507:Mice, 129 Strain; D018919:Neovascularization, Physiologic; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011973:Receptors, LDL / Q000378:metabolism; D015398:Signal Transduction; D015533:Transcriptional Activation; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000502:physiology*
chemical_list: D048049:Extracellular Signal-Regulated MAP Kinases; D016222:Fibroblast Growth Factor 2; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D011973:Receptors, LDL; D025521:Tumor Suppressor Proteins; D000511:alpha-Macroglobulins; C486645:Lrp1 protein, mouse; C496315:Nos3 protein, mouse