Akt and Ca2+ signaling in endothelial cells.
The protein kinase Akt participates in such important functions of endothelial cells as nitric oxide production and angiogenesis, activities that involve changes in cytosolic Ca2+ concentration. However, it is not known if activation of Akt is itself involved in the regulation of Ca2+ signals produced in these cells. The objective of this study was to examine if Akt is involved in the regulation of Ca2+ signaling in endothelial cells. Agonist-stimulated Ca2+ signals, assessed using fura-2, were compared in porcine aortic endothelial cells under control conditions or conditions in which Akt was blocked either by different inhibitors of phosphatidylinositol 3-kinase (PI3 kinase)/Akt or by transient expression of a dominant-negative form of Akt (dnAkt). We found that the release of intracellular Ca2+ stores stimulated by bradykinin or thapsigargin is not affected by the PI3 kinase inhibitors LY294002 and wortmannin, or by expression of dnAkt. LY294002 dose-dependently inhibits store-operated Ca2+ entry, an effect not seen with wortmannin. Expression of dnAkt has no effect on store-operated Ca2+ entry. We conclude that Akt is not involved in the regulation of agonist-stimulated Ca2+ signals in endothelial cells. The compound LY294002 inhibits store-operated Ca2+ entry in these cells by a mechanism independent of PI3 kinase/Akt inhibition.
Ozeki
Mariko
M
Department of Internal Medicine III, Hamamatsu University School of Medicine, Hamamatsu, Japan.
Watanabe
Hiroshi
H
Luo
Jinghui
J
Nakano
Tomoyasu
T
Takeuchi
Kazuhiko
K
Kureishi
Yasuko
Y
Ito
Masaaki
M
Nakano
Takeshi
T
Ohashi
Kyoichi
K
Hayashi
Hideharu
H
D000818:Animals; D001011:Aorta / Q000166:cytology; D001920:Bradykinin / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D042783:Endothelial Cells / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013552:Swine
D001920:Bradykinin; D004791:Enzyme Inhibitors; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011994:Recombinant Proteins