Document Detail


Mechanism of thrombin mediated eNOS phosphorylation in endothelial cells is dependent on ATP levels after stimulation.
MedLine Citation:
PMID:  18687367     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Conflicting results have been reported concerning the role of AMP-activated protein kinase (AMPK) in mediating thrombin stimulation of endothelial NO-synthase (eNOS). We examined the involvement of two upstream kinases in AMPK activation in cultured human umbilical endothelial cells, LKB1 stimulated by a rise in intracellular AMP/ATP ratio, and Ca(+2)/CaM kinase kinase (CaMKK) responding to elevation of intracellular Ca(+2). We also studied the effects of AMPK activation on the downstream target eNOS. In culture medium 1640 the level of intracellular ATP was unchanged after thrombin stimulation and the CaMKK inhibitor STO-609 totally inhibited phosphorylation of AMPK and acetyl coenzyme A carboxylase (ACC) but not eNOS. In Morgan's medium 199 thrombin caused a significant lowering of intracellular ATP and STO-609 only partially inhibited the phosphorylation of AMPK, ACC and eNOS. Inhibition of AMPK by Compound C or AMPK downregulation using siRNA partially inhibited the phosphorylation of eNOS in medium 199 but not in 1640, underscoring a clear difference in the pathways mediating thrombin-stimulated eNOS phosphorylation in different culture media. Thus, conditions subjecting endothelial cells to a fall in ATP after thrombin stimulation facilitate activation of pathways partly dependent on AMPK causing downstream phosphorylation of eNOS. In contrast, under culture conditions that do not facilitate a fall in ATP after stimulation, AMPK activation is exclusively mediated by CaMKK and does not contribute to the phosphorylation of eNOS.
Authors:
Brynhildur Thors; Haraldur Halldórsson; Gudbjorg Jónsdóttir; Gudmundur Thorgeirsson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-07-18
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1783     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-09-09     Completed Date:  2008-11-13     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  1893-902     Citation Subset:  IM    
Affiliation:
Institute of Pharmacy, Pharmacology and Toxicology, University of Iceland, Hagi Hofsvallagotu 53, Reykjavik, Iceland.
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MeSH Terms
Descriptor/Qualifier:
AMP-Activated Protein Kinases
Acetyl-CoA Carboxylase / metabolism
Adenosine Triphosphate / metabolism*,  secretion
Calcimycin / pharmacology
Cells, Cultured
Culture Media, Conditioned
Endothelial Cells / drug effects,  enzymology*
Humans
Multienzyme Complexes / metabolism
Nitric Oxide / biosynthesis
Nitric Oxide Synthase Type III / metabolism*
Phosphorylation
Protein-Serine-Threonine Kinases / metabolism
Thrombin / metabolism*
Chemical
Reg. No./Substance:
0/Culture Media, Conditioned; 0/Multienzyme Complexes; 10102-43-9/Nitric Oxide; 52665-69-7/Calcimycin; 56-65-5/Adenosine Triphosphate; EC 1.14.13.39/NOS3 protein, human; EC 1.14.13.39/Nitric Oxide Synthase Type III; EC 2.7.11.1/AMP-Activated Protein Kinases; EC 2.7.11.1/Protein-Serine-Threonine Kinases; EC 3.4.21.5/Thrombin; EC 6.4.1.2/Acetyl-CoA Carboxylase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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