Role of prostaglandins in the suppression of apoptosis in hen granulosa cells by transforming growth factor alpha.
Although transforming growth factor alpha (TGF-alpha) is known to be an important survival factor for granulosa cells, the cellular and molecular mechanisms involved are uncertain. The purpose of the present study was to investigate the possible involvement of prostaglandins in the anti-apoptotic action of TGF-alpha. Hen granulosa cells from healthy prehierarchical follicles (2-6 mm) cultured in serum-free medium underwent spontaneous apoptosis as demonstrated by DNA fragmentation and nuclear chromatin condensation. TGF-alpha (20 ng ml(-1)) stimulated maximum synthesis of prostaglandins (PGE and PGF) in granulosa cells and completely inhibited serum deprivation-induced apoptosis. The addition of an inhibitor of cyclooxygenase (COX; N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide (NS398) or ibuprofen) or phospholipase A(2) (PLA(2); aristolochic acid, 2-p-amylcinnamoyl amino-4-chlorobenzoic acid (ONO-RS-82) or arachidonyl triflouro methyl ketone (TFMK)), to the culture medium markedly suppressed the TGF-alpha-induced prostaglandin synthesis and significantly increased granulosa cell apoptosis. The apoptotic effect of NS398 and aristolochic acid was completely inhibited by exogenous prostaglandins (PGF(2 alpha), PGE(1), PGE(2)) and arachidonic acid, respectively. However, exogenous prostaglandins failed to inhibit the PLA(2) inhibitor-induced apoptotic DNA fragmentation, implying that in addition to prostaglandins, arachidonic acid or leukotrienes may be important in transducing the anti-apoptotic action of TGF-alpha. In the absence of exogenous TGF-alpha, prostaglandins had no significant influence on granulosa cell apoptosis induced by serum withdrawal. These findings indicate that prostaglandin synthesis is a necessary, but not sufficient, event in the suppression of granulosa cell apoptosis by TGF-alpha. Whether arachidonic acid or leukotrienes are important in the anti-apoptotic action of TGF-alpha in hen granulosa cells remains to be determined.
Manchanda
R
R
Reproductive Biology Unit, Department of Obstetrics and Gynaecology, University of Ottawa, Ottawa Health Research Institute, The Ottawa Hospital (Civic Campus), Ottawa, Ontario, Canada K1Y 4E9.
Kim
J M
JM
Tsang
B K
BK
D000527:Alprostadil / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016718:Arachidonic Acid / Q000494:pharmacology; D001095:Arachidonic Acids / Q000494:pharmacology; D034341:Aristolochic Acids; D002478:Cells, Cultured; D002645:Chickens; D002843:Chromatin / Q000648:ultrastructure; D016895:Culture Media, Serum-Free; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D015237:Dinoprost / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006107:Granulosa Cells / Q000166:cytology*; D007052:Ibuprofen / Q000494:pharmacology; D009578:Nitrobenzenes / Q000494:pharmacology; D010616:Phenanthrenes / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D011453:Prostaglandins / Q000502:physiology*; D011458:Prostaglandins E / Q000096:biosynthesis; D011460:Prostaglandins F / Q000096:biosynthesis; D013449:Sulfonamides / Q000494:pharmacology; D016211:Transforming Growth Factor alpha / Q000494:pharmacology*
D001095:Arachidonic Acids; D034341:Aristolochic Acids; D002843:Chromatin; D016895:Culture Media, Serum-Free; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D009578:Nitrobenzenes; D010616:Phenanthrenes; D011453:Prostaglandins; D011458:Prostaglandins E; D011460:Prostaglandins F; D013449:Sulfonamides; D016211:Transforming Growth Factor alpha; C081565:arachidonyltrifluoromethane; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D016718:Arachidonic Acid; C000228:aristolochic acid I; D015237:Dinoprost; D010741:Phospholipases A; D000527:Alprostadil; D015232:Dinoprostone; D007052:Ibuprofen