Differential effects of PPARgamma ligands on oxidative stress-induced death of retinal pigmented epithelial cells.
OBJECTIVE
To investigate the role of the peroxisome proliferator-activated receptor (PPAR)-γ in modulating retinal pigmented epithelium (RPE) responses to oxidative stress.


METHODS
ARPE-19 cells were treated with the oxidant, t-butylhydroperoxide (tBH) to induce apoptosis. Cells pretreated with synthetic PPARγ agonists of the antidiabetic thiazolidinediones class before tBH challenge were assessed for viability and, by microarray analysis, for effects on gene expression.


RESULTS
Treatment of ARPE-19 cells with tBH resulted in a loss of viability and global changes in the pattern of gene expression. PPARγ ligands were found to have differential modulatory effects on tBH-induced apoptosis of RPE cells. Whereas rosiglitazone and pioglitazone potentiated cell death, troglitazone acted as a potent cytoprotective agent. Downregulation of PPARγ expression by an siRNA resulted in enhanced cell death in response to tBH treatment and blocked the cytoprotective effect of troglitazone consistent with a role of PPARγ in mediating this response. Microarray analysis revealed that while rosiglitazone and pioglitazone had little effect on gene changes induced by tBH treatment, troglitazone dramatically reduced the number of changes caused by oxidative stress. A unique subset of genes that were deregulated by tBH and selectively normalized by troglitazone were identified.


CONCLUSIONS
These findings demonstrate that PPARγ agonists can have differential effects on RPE survival in response to oxidative stress. Oxidative stress leads to deregulation of a large set of genes in ARPE-19 cells. A specific subset of these genes can be selectively modulated by troglitazone and represent potential novel targets for cytoprotective therapies.
Rodrigues
Gerard A
GA
Biological Sciences, Allergan, Inc., Irvine, California 92612, USA. rodrigues_gerry@allergan.com
Maurier-Mahé
Florence
F
Shurland
Dixie-Lee
DL
McLaughlin
Anne
A
Luhrs
Keith
K
Throo
Emeline
E
Delalonde-Delaunay
Laurence
L
Pallares
Diego
D
Schweighoffer
Fabien
F
Donello
John
J
D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D004357:Drug Synergism; D020868:Gene Silencing / Q000502:physiology; D006801:Humans; D008024:Ligands; D046228:Microarray Analysis; D018384:Oxidative Stress / Q000187:drug effects*; D047495:PPAR gamma / Q000819:agonists / Q000378:metabolism*; D000077205:Pioglitazone; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology*; D014162:Transfection; D020122:tert-Butylhydroperoxide / Q000633:toxicity
D008024:Ligands; D047495:PPAR gamma; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D020122:tert-Butylhydroperoxide; D053148:Caspase 3; D000077205:Pioglitazone