Oxidized LDL inhibits vascular endothelial growth factor-induced endothelial cell migration by an inhibitory effect on the Akt/endothelial nitric oxide synthase pathway.
BACKGROUND
Oxidized LDL (oxLDL) inhibits endothelial cell (EC) migration. Stimulating ECs with vascular endothelial growth factor (VEGF) leads to the activation of Akt/protein kinase B, which in turn activates endothelial nitric oxide synthase (eNOS) by phosphorylation on serine 1177. VEGF-induced cell migration is dependent on the generation of nitric oxide (NO). Therefore, we investigated whether oxLDL affects EC migration by an inhibitory effect on the Akt/eNOS pathway.


RESULTS
During an in vitro "scratched wound assay," oxLDL dose-dependently inhibited the VEGF-induced migration of human umbilical vein endothelial cells. Western blot analysis revealed that oxLDL dose- and time-dependently led to dephosphorylation and thus deactivation of Akt. Moreover, oxLDL inhibited the VEGF-induced generation of NO, as detected and quantified using a fluorescent NO indicator, 4,5-diaminofluorescein diacetate. Overexpression of a constitutively active Akt construct (Akt T308D/S473D) or a phosphomimetic eNOS construct (eNOS S1177D) almost completely reversed the inhibitory effect of oxLDL on VEGF-induced EC migration and NO generation.


CONCLUSIONS
Our data indicate that oxLDL-induced dephosphorylation of Akt, followed by impaired eNOS activation, reduces the intracellular level of NO and thereby inhibits VEGF-induced EC migration.
Chavakis
E
E
Department of Internal Medicine IV, University of Frankfurt, Germany.
Dernbach
E
E
Hermann
C
C
Mondorf
U F
UF
Zeiher
A M
AM
Dimmeler
S
S
D019943:Amino Acid Substitution; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008222:Lymphokines / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008077:Lipoproteins, LDL; D008222:Lymphokines; D011518:Proto-Oncogene Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C099252:oxidized low density lipoprotein; D009569:Nitric Oxide; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt