Decreased expression of tumor necrosis factor-alpha-stimulated gene 6 in cumulus cells of the cyclooxygenase-2 and EP2 null mice.
Ovulation, the release of fertilizable oocytes from mature follicles, involves tissue remodeling and increased prostaglandin (PG) signaling. Cyclooxygenase (COX)-2 is the rate-limiting enzyme during PG synthesis. Female mice null for either COX-2 or the PGE(2) receptor EP2 are infertile, show decreased ovulation, and exhibit abnormal cumulus expansion. Cumulus expansion is the production of a complex extracellular matrix surrounding the cumulus-oocyte complex (COC). Matrix components consist of hyaluronan, proteoglycans, and proteins with hyaluronan binding domains. One such hyaluronan binding protein is TNFalpha-stimulated gene 6 (TSG-6). By various methods, we show induction of TSG-6 and hyaluronan synthase-2 mRNA in ovaries of mice treated with pregnant mare serum gonadotropin and human chorionic gonadotropin. By in situ hybridization, we show that both genes are expressed in periantral mural granulosa cells and cumulus cells of the mouse ovary. Notably, RT-PCR and in situ hybridization show that TSG-6 mRNA but not hyaluronan synthase-2 mRNA expression is selectively reduced in cumulus cells of COX-2 and EP2 null mice. Western analysis further confirms that TSG-6 protein is reduced in isolated COCs but remains covalently associated with inter alpha-trypsin inhibitor in COX-2 null mice. These observations identify TSG-6 as a target of PG action and show that its production in ovulatory follicles is associated with proper formation of the cumulus-derived extracellular matrix.
Ochsner
Scott A
SA
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
Russell
Darryl L
DL
Day
Anthony J
AJ
Breyer
Richard M
RM
Richards
Joanne S
JS
D000510:Alpha-Globulins / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000235:genetics*; D051546:Cyclooxygenase 2; D005260:Female; D015870:Gene Expression; D014453:Glucuronosyltransferase / Q000235:genetics; D000076002:Hyaluronan Synthases; D017403:In Situ Hybridization; D007527:Isoenzymes / Q000172:deficiency*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D006080:Ovarian Follicle / Q000737:chemistry*; D011451:Prostaglandin-Endoperoxide Synthases / Q000172:deficiency*; D012333:RNA, Messenger / Q000032:analysis; D018078:Receptors, Prostaglandin E / Q000172:deficiency*; D058307:Receptors, Prostaglandin E, EP2 Subtype; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000510:Alpha-Globulins; D015815:Cell Adhesion Molecules; D007527:Isoenzymes; C545644:PTGER2 protein, human; C545645:Ptger2 protein, mouse; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D058307:Receptors, Prostaglandin E, EP2 Subtype; C513057:Tnfaip6 protein, mouse; C011877:inter-alpha-inhibitor; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D014453:Glucuronosyltransferase; C491099:Has2 protein, mouse; D000076002:Hyaluronan Synthases