Modulation of Ca2+ transients in cultured endothelial cells in response to fluid flow through alphav integrin.
In order to determine whether integrin dynamics is associated with intracellular Ca(2+) concentration ([Ca(2+)](i)) mobilization in ECs in response to hemodynamic forces, changes in [Ca(2+)](i) in fluo-4-loaded cultured bovine aortic endothelial cells (BAECs) under fluid flow conditions were visualized employing laser scanning confocal microscopy. Following the onset of flow stimulus, transient increases in [Ca(2+)](i) occurred several times in individual BAECs during the 30-min observation period. The frequency of these [Ca(2+)](i) transients was clearly reduced by the application of an integrin antagonist (GRGDSP peptide). Furthermore, treatment of cells with an integrin activator (Mn(2+)) resulted in reduction of peak [Ca(2+)](i) levels and elevated frequency, which was markedly rescued upon GRGDSP administration. In contrast, an actin de-polymerizing agent (cytochalasin D) exerted no inhibitory effects; rather, cytochalasin D more likely facilitated [Ca(2+)](i) transients. Moreover, [Ca(2+)](i) transients, which were suppressed by short interference RNA-induced silencing of alphav integrin, exhibited greater frequently in cells cultured on vitronectin substratum in comparison with those cultured on fibronectin or collagen substratum. Either removal of extracellular Ca(2+), application of an inhibitor of endoplasmic reticulum Ca(2+)-ATPase (thapsigargin) or non-selective cation channel blocker (La(3+)) inhibited the [Ca(2+)](i) transients. Additionally, [Ca(2+)](i) transients were attenuated by extracellular signal-regulated kinase (ERK) kinase inhibitor (U0126); in contrast, [Ca(2+)](i) transients were unaffected by tyrosine kinase inhibitor (genistein) or phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002). Therefore, our findings revealed that alphav integrin dynamics modulates the frequency of flow-induced [Ca(2+)](i) transients in BAECs in an ERK-dependent fashion.
Miyazaki
Takuro
T
Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan. taku@pharm.showa-u.ac.jp
Honda
Kazuo
K
Ohata
Hisayuki
H
D000199:Actins / Q000378:metabolism; D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D024141:Collagen Type IV / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005353:Fibronectins / Q000494:pharmacology; D039564:Integrin alphaV / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008345:Manganese / Q000494:pharmacology; D018613:Microscopy, Confocal; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008954:Models, Biological; D009570:Nitriles / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D034622:RNA Interference; D012212:Rheology / Q000379:methods; D013314:Stress, Mechanical; D019096:Vitronectin / Q000494:pharmacology
D000199:Actins; D002070:Butadienes; D024141:Collagen Type IV; D004791:Enzyme Inhibitors; D005353:Fibronectins; D039564:Integrin alphaV; D009570:Nitriles; D009842:Oligopeptides; C113580:U 0126; D019096:Vitronectin; D008345:Manganese; C058161:glycyl-arginyl-glycyl-aspartyl-seryl-proline; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D002118:Calcium