The prominent role of p38 mitogen-activated protein kinase in insulin-mediated enhancement of VCAM-1 expression in endothelial cells.
Insulin levels are a marker for cardiovascular events, but the link between hyperinsulinemia and atherosclerosis is poorly understood. We previously showed that insulin increases monocyte-endothelial interactions and the endothelial expression of the pro-atherogenic vascular cell adhesion molecule-1 (VCAM-1). The aim of this study is to examine molecular mechanisms involved in the effect of insulin on VCAM-1 expression. Human umbilical vein endothelial cells (HUVEC) were incubated with insulin (0-24 h)+/- inhibitors of signaling pathways potentially involved. At pathophysiological concentrations (10(-9)-10(-7) M), insulin selectively induced VCAM-1 expression. The p38 mitogen activated protein(MAP) kinase inhibitors SB203580 and SB202190, and partially the c-Jun NH2-terminal kinase (JNK) inhibitor SP600127, decreased insulin effect on VCAM-1. Gene silencing by small interfering RNA significantly reduced the expression of p38MAP kinase, and this was accompanied by suppression of insulin-stimulated VCAM-1 expression. Treatment with insulin also led to the activation of NF-KB and induction of IKB-alpha phosphorylation, thus accounting for NF-KB translocation into the nucleus. Co-treatment of HUVEC with insulin and SB202190 strongly reverted the stimulatory effect of insulin on NF-KB activation, thus establishing a link between NF-KB activation and p38MAPkinase-mediated induction of VCAM-1 by insulin. In conclusion, pathophysiological insulin concentrations increase VCAM-1 expression and activate NF-KB. This mostly occurs through stimulation of p38MAP kinase.
Madonna
R
R
Center of Excellence on Aging, G.d'Annunzio University, Chieti, Italy.
Massaro
M
M
Pandolfi
A
A
Consoli
A
A
De Caterina
R
R
D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D020672:I-kappa B Proteins / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D007328:Insulin / Q000494:pharmacology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D014162:Transfection; D015854:Up-Regulation; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*
D004791:Enzyme Inhibitors; D007004:Hypoglycemic Agents; D020672:I-kappa B Proteins; D007328:Insulin; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D019010:Vascular Cell Adhesion Molecule-1; D000072000:NF-KappaB Inhibitor alpha; D048051:p38 Mitogen-Activated Protein Kinases