Peroxisome proliferator-activated receptor gamma ligands stimulate endothelial nitric oxide production through distinct peroxisome proliferator-activated receptor gamma-dependent mechanisms.
OBJECTIVE
We recently reported that the peroxisome proliferator-activated receptor gamma (PPARgamma) ligands 15-deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) and ciglitazone increased cultured endothelial cell nitric oxide (NO) release without increasing the expression of endothelial nitric oxide synthase (eNOS). The current study was designed to characterize further the molecular mechanisms underlying PPARgamma-ligand-stimulated increases in endothelial cell NO production.


RESULTS
Treating human umbilical vein endothelial cells (HUVEC) with PPARgamma ligands (10 micromol/L 15d-PGJ2, ciglitazone, or rosiglitazone) for 24 hours increased NOS activity and NO release. In selected studies, HUVEC were treated with PPARgamma ligands and with the PPARgamma antagonist GW9662 (2 micromol/L), which fully inhibited stimulation of a luciferase reporter gene, or with small interfering RNA to PPARgamma, which reduced HUVEC PPARgamma expression. Treatment with either small interfering RNA to PPARgamma or GW9662 inhibited 15d-PGJ2-, ciglitazone-, and rosiglitazone-induced increases in endothelial cell NO release. Rosiglitazone and 15d-PGJ2, but not ciglitazone, increased heat shock protein 90-eNOS interaction and eNOS ser1177 phosphorylation. The heat shock protein 90 inhibitor geldanamycin attenuated 15d-PGJ2- and rosiglitazone-stimulated NOS activity and NO production.


CONCLUSIONS
These findings further clarify mechanisms involved in PPARgamma-stimulated endothelial cell NO release and emphasize that individual ligands exert their effects through distinct PPARgamma-dependent mechanisms.
Polikandriotis
John A
JA
Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA, USA. jpolika@emory.edu
Mazzella
Louis J
LJ
Rupnow
Heidi L
HL
Hart
C Michael
CM
D000813:Anilides / Q000494:pharmacology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D008024:Ligands; D009569:Nitric Oxide / Q000378:metabolism*; D047495:PPAR gamma / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D015230:Prostaglandin D2 / Q000031:analogs & derivatives / Q000494:pharmacology; D034741:RNA, Small Interfering; D000077154:Rosiglitazone; D015398:Signal Transduction / Q000187:drug effects; D045162:Thiazolidinediones / Q000494:pharmacology*; D014471:Umbilical Veins / Q000166:cytology
C477819:15-deoxyprostaglandin J2; C457499:2-chloro-5-nitrobenzanilide; D000813:Anilides; D007004:Hypoglycemic Agents; D008024:Ligands; D047495:PPAR gamma; D034741:RNA, Small Interfering; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D009569:Nitric Oxide; D015230:Prostaglandin D2; C039671:ciglitazone