Peroxisome proliferator-activated receptor gamma is required for the inhibitory effect of ciglitazone but not 15-deoxy-Delta 12,14-prostaglandin J2 on the NFkappaB pathway in human endothelial cells.
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-activated nuclear receptor with effects on inflammation, atherosclerosis, and apoptosis. The endogenous PPARgamma ligand, 15-deoxy-Delta12,14-PGJ2 (15d-PGJ2), and the synthetic ligand, ciglitazone, have anti-inflammatory properties in endothelial cells. In addition to PPARgamma-dependent effects on the anti-inflammatory process, it has been proposed that PPARgamma ligands may also inhibit the nuclear transcription factor kappaB (NFkappaB) pathway in a PPARgamma-independent manner. The purpose of this study was to compare the effects of 15d-PGJ2 and ciglitazone on the cytokine-induced activation of the NFkappaB pathway. Human umbilical vein endothelial cells (HUVECs) were transiently transfected with NFkappaB-luciferase or PPARgamma elements-luciferase reporter constructs for 48 h. The HUVECs were pretreated with 15d-PGJ2 or ciglitazone (30 microM) for 1 h, followed by a 4-h stimulation with tumor necrosis factor alpha (100 U/mL). Luciferase assay was performed to determine reporter activity. Additionally, HUVECs were transiently transfected with a dominant-negative mutant, which retains ligand and DNA binding but exhibits markedly reduced transactivation. Stimulation of HUVEC with tumor necrosis factor alpha increased NFkappaB activation while decreasing PPARgamma activity. Overexpression of a dominant-negative PPARgamma mutant prevented the inhibitory effect of ciglitazone on cytokine-induced NFkappaB activation in transfected human endothelial cells. Conversely, 15d-PGJ2 inhibited the cytokine-induced NFkappaB activation even in the absence of PPARgamma. Our data suggest that 15d-PGJ2 exerts direct inhibitory effects on the NFkappaB pathway through a PPARgamma-independent mechanism. On the contrary, the inhibitory effect of ciglitazone on the NFkappaB pathway seems to require PPARgamma activation.
Kaplan
Jennifer
J
Cincinnati Children's Hospital Medical Center, 3229 Burnet Avenue, Cincinnati, OH 45229, USA.
Cook
James A
JA
O'Connor
Michael
M
Zingarelli
Basilia
B
D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019040:E-Selectin / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism*; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D045162:Thiazolidinediones / Q000494:pharmacology*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
C097240:15-deoxy-delta(12,14)-prostaglandin J2; D019040:E-Selectin; D016328:NF-kappa B; D047495:PPAR gamma; D011993:Recombinant Fusion Proteins; D045162:Thiazolidinediones; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D008156:Luciferases; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D015230:Prostaglandin D2; C039671:ciglitazone