The role of caveolin-1 in PCB77-induced eNOS phosphorylation in human-derived endothelial cells.
Polychlorinated biphenyls (PCBs) may contribute to the pathology of atherosclerosis by activating inflammatory responses in vascular endothelial cells. Endothelial nitric oxide synthase (eNOS) is colocalized with caveolae and is a critical regulator of vascular homeostasis. PCBs may be proatherogenic by causing dysfunctional eNOS signaling. The objective of this study was to investigate the role of caveolin-1 in PCB-induced endothelial dysfunction with a focus on mechanisms associated with eNOS signaling. Cells derived from an immortalized human vascular endothelial cell line were treated with PCB77 to study nitrotyrosine formation through eNOS signaling. Phosphorylation studies of eNOS, caveolin-1, and kinases, such as Src, phosphatidylinositol 3-kinase (PI3K), and Akt, were conducted in cells containing either functional or small-interfering RNA-silenced caveolin-1 protein. We also investigated caveolin-1-regulated mechanisms associated with PCB-induced markers of peroxynitrite formation and DNA binding of NF-kappaB. Cellular exposure to PCB77 increased eNOS phosphorylation and nitric oxide production, as well as peroxynitrite levels. A subsequent PCB-induced increase in NF-kappaB DNA binding may have implications in oxidative stress-mediated inflammatory mechanisms. The activation of eNOS by PCB77 treatment was blocked by inhibitors of the Src/PI3K/Akt pathway. PCB77 also increased phosphorylation of caveolin-1, indicating caveolae-dependent endocytosis. Caveolin-1 silencing abolished both the PCB-stimulated Akt and eNOS phosphorylation, suggesting a regulatory role of caveolae in PCB-induced eNOS signaling. These findings suggest that PCB77 induces eNOS phosphorylation in endothelial cells through a Src/PI3K/Akt-dependent mechanism, events regulated by functional caveolin-1. Our data provide evidence that caveolae may play a critical role in regulating vascular endothelial cell activation and toxicity induced by persistent environmental pollutants such as coplanar PCBs.
Lim
Eun Jin
EJ
Molecular and Cell Nutrition Laboratory, University of Kentucky, Lexington, KY 40536-0200, USA.
Smart
Eric J
EJ
Toborek
Michal
M
Hennig
Bernhard
B
D000818:Animals; D050197:Atherosclerosis / Q000139:chemically induced / Q000378:metabolism; D021941:Caveolae / Q000187:drug effects* / Q000378:metabolism; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity*; D004789:Enzyme Activation; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013552:Swine; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D051242:Caveolin 1; D004785:Environmental Pollutants; D016328:NF-kappa B; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D030421:Peroxynitrous Acid; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011078:Polychlorinated Biphenyls; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D014443:Tyrosine; D019061:src-Family Kinases; C002744:3-nitrotyrosine; C496314:NOS3 protein, human; C028451:3,4,3',4'-tetrachlorobiphenyl