Activated protein C induces endothelial cell proliferation by mitogen-activated protein kinase activation in vitro and angiogenesis in vivo.
Activated protein C (APC), a natural anticoagulant, has recently been demonstrated to activate the mitogen-activated protein kinase (MAPK) pathway in endothelial cells in vitro. Because the MAPK pathway is implicated in endothelial cell proliferation, it is possible that APC induces endothelial cell proliferation, thereby causing angiogenesis. We examined this possibility in the present study. APC activated the MAPK pathway, increased DNA synthesis, and induced proliferation in cultured human umbilical vein endothelial cells dependent on its serine protease activity. Antibody against the endothelial protein C receptor (EPCR) inhibited these events. Early activation of the MAPK pathway was inhibited by an antibody against protease-activated receptor-1, whereas neither late and complete activation of the MAPK pathway nor endothelial cell proliferation were inhibited by this antibody. APC activated endothelial nitric oxide synthase (eNOS) via phosphatidylinositol 3-kinase-dependent phosphorylation, followed by activation of protein kinase G, suggesting that APC bound to EPCR might activate the endothelial MAPK pathway by a mechanism similar to that of VEGF. APC induced morphogenetic changes resembling tube-like structures of endothelial cells, whereas DIP-APC did not. When applied topically to the mouse cornea, APC clearly induced angiogenesis in wild-type mice, but not in eNOS knockout mice. These in vitro events induced by APC might at least partly explain the angiogenic activity in vivo. This angiogenic activity of APC might contribute to maintain proper microcirculation in addition to its antithrombotic activity.
Uchiba
Mitsuhiro
M
Department of Diagnostic Medicine, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, 860-0811, Japan.
Okajima
Kenji
K
Oike
Yuichi
Y
Ito
Yasuhiro
Y
Fukudome
Kenji
K
Isobe
Hirotaka
H
Suda
Toshio
T
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001779:Blood Coagulation Factors / Q000276:immunology; D049109:Cell Proliferation; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D018919:Neovascularization, Physiologic; D009569:Nitric Oxide / Q000096:biosynthesis; D011486:Protein C / Q000494:pharmacology* / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D044463:Receptor, PAR-1 / Q000276:immunology; D011956:Receptors, Cell Surface / Q000276:immunology
D000906:Antibodies; D001779:Blood Coagulation Factors; D011486:Protein C; D047428:Protein Kinase Inhibitors; D044463:Receptor, PAR-1; D011956:Receptors, Cell Surface; C091963:activated protein C receptor; D009569:Nitric Oxide; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases; D006152:Cyclic GMP