Submission Number: THO-4-31-2
Abstract Number: 32
INTERFERON-TAU SUPPRESSES PROSTAGLANDIN F2 RELEASE THROUGH A MAP KINASE- AND NFB-INDEPENDENT MECHANISM.
Thomas R Hansen* 1, James K Pru* 1, Bo R Rueda* 2, Kathy J Austin* 1, Aydin Guzeloglu 3 and William W Thatcher* 3
Department of Animal Science, University of Wyoming, Laramie, WY 1
Vincent Center for Reproductive Biology, Massachusetts General Hospital, Boston, MA 2
Department of Dairy and Poultry Sciences, University of Florida, Gainesville, FL 3
Pregnancy is established in ruminants through inhibitory actions of interferon (IFN)-tau on the release of prostaglandin F2 (PGF). Consequently, the corpus luteum survives and continues to produce progesterone. The purpose of this study was to delineate the signal transduction cascade for synthesis of PGF, and to determine if IFN-tau inhibits PGF release through Raf-1/MEK-1/MAPK-ERKs or NFB pathways in cultured bovine endometrial (BEND) cells. BEND cells were untreated (control) or treated for 0, 5, 10, 60, 180 or 300 min with PDBu (phorbol ester; 100 ng/ml), IFN-tau (50 or 500 ng/ml), PDBu & IFN-tau, or PDBu & PD098059 (MEK-1 inhibitor; 50 mM). PDBu induced (P<0.05) PGF release within 3 h. This induction of PGF by PDBu was inhibited 75% with the addition of IFN-tau (P<0.05) and was ablated completely by PD098059. Parallel results were obtained for cyclooxygenase (COX)-2 protein expression, while phospholipase A2 remained unchanged across treatments. Thus, the site of IFN-tau action using this model excludes a direct action on oxytocin or estradiol receptors. PDBu-induced phosphorylation of MAPK was not altered by IFN-tau. Also, Raf-1 hyperphosphorylation was sustained in response to PDBu regardless of IFN-tau treatment. This is interpreted to mean that feedback on Raf-1 hyperphosphorylation via MAPK remained intact. PDBu induced (P<0.05) transcription of c-jun and c-fos mRNAs within 30 min. This was inhibited (P<0.05) by PD098059, but not by IFN-tau. Only the 500 ng/ml concentration of IFN-tau reduced (P<0.05) IB levels. However, both concentrations of IFN-tau (50 and 500 ng/ml) inhibited (P<0.05) induction of COX-2 protein by PDBu. Thus, nuclear translocation of NFB is probably not the site through which IFN-tau inhibits COX-2 gene expression. In conclusion, PGF synthesis is mediated through the MAPK pathway, but this pathway is not disrupted by IFN-tau. It is hypothesized that signal transducers and activators of transcription or IFN regulatory factors act directly to inhibit the COX-2 gene. NIH HD32475-06.
Keywords: Interferon Prostaglandin Uterus
This abstract is being presented at: 3:45 PM in session:
SESSION 5: SIGNAL TRANSDUCTION IN REPRODUCTIVE TISSUES