Mechanism of fluoride-induced MAP kinase activation in pulmonary artery endothelial cells.
In this study, we demonstrate that challenge of endothelial cells (EC) with NaF, a recognized G protein activator and protein phosphatase inhibitor, leads to a significant Erk activation, with increased phosphorylation of the well-known Erk substrate caldesmon. Inhibition of the Erk MAPK, MEK, by U0126 produces a marked decrease in NaF-induced caldesmon phosphorylation. NaF transiently increases the activity of the MEK kinase known as Raf-1 (approximately 3- to 4-fold increase over basal level), followed by a sustained Raf-1 inhibition (approximately 3- to 4-fold decrease). Selective Raf-1 inhibitors (ZM-336372 and Raf-1 inhibitor 1) significantly attenuate NaF-induced Erk and caldesmon phosphorylation. Because we have previously shown that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) participates in Erk activation in thrombin-challenged cells, we next explored if CaMKII is involved in NaF-induced EC responses. We found that in NaF-treated EC, CaMKII activity increases in a time-dependent manner with maximal activity at 10 min (approximately 4-fold increase over a basal level). Pretreatment with KN93, a specific CaMKII inhibitor, attenuates NaF-induced barrier dysfunction and Erk phosphorylation. The Rho inhibitor C3 exotoxin completely abolishes NaF-induced CaMKII activation. Collectively, these data suggest that sequential activation of Raf-1, MEK, and Erk is modulated by Rho-dependent CaMKII activation and represents important NaF-induced signaling response. Caldesmon phosphorylation occurring by an Erk-dependent mechanism in NaF-treated pulmonary EC may represent a link between NaF stimulation and contractile responses of endothelium.
Bogatcheva
Natalia V
NV
Section of Pulmonary and Critical Care, Department of Medicine, University of Chicago, 5841 S. Maryland Avenue, W604, Chicago, IL 60637, USA.
Wang
Peiyi
P
Birukova
Anna A
AA
Verin
Alexander D
AD
Garcia
Joe G N
JG
D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002417:Cattle; D004730:Endothelium, Vascular / Q000201:enzymology* / Q000502:physiology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005459:Fluorides / Q000494:pharmacology*; D007700:Kinetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D009570:Nitriles / Q000494:pharmacology; D011651:Pulmonary Artery / Q000201:enzymology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012969:Sodium Fluoride / Q000494:pharmacology
D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; C113580:U 0126; D012969:Sodium Fluoride; D020928:Mitogen-Activated Protein Kinases; D005459:Fluorides