Mechanism of fluoride-induced MAP kinase activation in pulmonary artery endothelial cells

Natalia V. Bogatcheva, Peiyi Wang, Anna A. Birukova, Alexander D. Verin, Joe G.N. Garcia

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


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 (∼3- to 4-fold increase over basal level), followed by a sustained Raf-1 inhibition (∼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 Ca2+/ 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 (∼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.

Original languageEnglish (US)
Pages (from-to)L1139-L1145
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Issue number6
StatePublished - Jun 2006


  • Cytoskeleton
  • Intracellular signaling in endothelium
  • Mitogen-activated protein kinase

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology


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