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Mechanisms of Hormone Action |
a Département d'Ontogénie et Reproduction, Centre de Recherches du Centre Hospitalier Universitaire de Québec (CHUL), Centre de Recherche en Biologie de la Reproduction (CRBR)
b Département d'Obstétrique et Gynécologie, Université Laval, Ste-Foy, Quebec, Canada G1V 4G2
c Department of Animal Sciences, University of Missouri, Columbia, Missouri 65211
d Department of Dairy & Animal Science, Pennsylvania State University, The Almquist Research Center, University Park, Pennsylvania 16802
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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) is recognized as the embryonic signal responsible for maternal recognition of pregnancy. IFN- is believed to act by down-regulating estrogen receptors, thus preventing appearance of oxytocin receptors responsible for the release of prostaglandin F2
(PGF2) by the endometrium. The present study was undertaken to determine in vitro the biological activities of different IFN- isoforms and document putative alternate luteotrophic mechanisms. Endometrial cells in primary cultures were treated with five different rIFN- isoforms: two ovine isoforms (ro-4 and ro-11) and three bovine isoforms (rb-1a, rb-2b and rb-3b). Their effect was quantified by measurement of PGE2 and PGF2 production by ELISA and induction of cyclooxygenase (COX-2) by Western and Northern analysis and correlated with antiviral activity previously reported. The overall pattern of response to the IFNs tested suggests that low concentrations (<1 µg/ml) reduced the production of both PGs and higher concentrations (>1 µg/ml) stimulated preferentially PGE2; however, exceptions were noted. Isoform rb-2b with high antiviral activity inhibited PG production in both cell types at all concentrations tested. IFNs rb-1a and ro-11 had similar antiviral activities, inhibiting PG at low concentrations and stimulating them at high concentrations. Isoform rb-3b stands out relative to the other IFNs tested because it induced a variable non-dose-dependent effect on PG production and low antiviral activity. An increase in COX-2 protein expression and messenger was correlated with increased PG production. The results showing two distinct responses to IFN- depending on its concentration and/or isoform and the absence of correlation with antiviral activity suggest that complex transduction mechanisms are involved.
cytokines, embryo, female reproductive tract, mechanisms of hormone action, oxytocin
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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(PGF2) of uterine origin is responsible for luteolysis [2] through a positive feedback loop involving oxytocin (OT) [3]. By contrast, prostaglandin E2 (PGE2) may have a luteotrophic and/or antiluteolytic action [4, 5]. At the time of maternal recognition of pregnancy, a signal coming from the embryo has to be released to maintain the function of the corpus luteum. Trophoblastic interferon (IFN-) has been identified as the embryonic signal in ruminants, and it acts locally within the uterus [6] through type 1 IFN receptors present in the endometrium [7]. Maximal production of IFN- occurs on Days 15–19 of pregnancy [8]. Numerous polymorphic variants of IFN- have been identified in ruminant species. Presently, 18 naturally occurring ovine IFN- (ovIFN-) variants and 12 bovine IFN- (boIFN-) variants have been discovered by genomic and cDNA screening (reviewed in [9]). Several recombinant proteins have been generated for ovine and bovine IFN- variants [10–16]. All variants possess antiviral activity but exhibit different biological activities [17]. Moreover, ovIFN- variants differ in their ability to prevent corpus luteum (CL) regression when injected into the uterine lumen of nonpregnant ewes [10, 11], suggesting that some may be better pregnancy recognition factors.
We have found that IFN- increased PGE2 production and stimulated COX-2, the inducible form of cyclooxygenase in bovine endometrial cells in culture [18]. In contrast, OT increased PGF2 in a time- and dose-dependent manner in cultured epithelial but not stromal cells [19]. The in vitro responses to OT and IFN- are coherent with luteolytic and luteotrophic responses induced in vivo by the same agents. Therefore, endometrial cells in culture appear to constitute a good model to test and predict the physiological effect of different isoforms of IFN-. The current method to determine biological activities of recombinant IFN- is an in vitro assay system based on viral replication. The present study was undertaken to compare five recombinant IFN- proteins, three from the bovine (rb-1a, rb-2b, and rb-3b) and two from the ovine (ro-4 and ro-11) (see Table 1), using our in vitro system of primary endometrial cells in culture. These IFNs were previously characterized and exhibited a wide range of antiviral activity. The effect of the different IFNs tested on prostaglandin production was compared with their antiviral activity.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Tissue culture plates were purchased from Becton Dickinson (Lincoln Park, NJ). RPMI-1640 was obtained from ICN Biomedicals (Aurora, OH). Fetal bovine serum and TRIzol reagent were obtained from Gibco BRL (Canadian Life Technologies, Burlington, ON, Canada). DNA labeling kits (dCTP) and Hybond-C nitrocellulose membrane were purchased from Amersham Pharmacia Biotech (Baie d'Urfé, QC, Canada). Tracers for PGE2 and PGF2 used in the enzyme immunoassay were purchased from Cayman Chemical Co. (Ann Arbor, MI). BrightStar Plus membrane and ULTRAhyb solution were purchased from Ambion Inc. (Austin, TX). [-32P] dCTP radioactivity was obtained from Perkin-Elmer (Boston, MA). Renaissance Western blot chemiluminescence reagent and prestained protein markers were purchased from Mandel Scientific-New England Nuclear Life Science Products (Mississauga, ON, Canada). The goat anti-rabbit antibody conjugated to horseradish peroxidase was obtained from Jackson Immunoresearch Laboratories (West Grove, PA). Oxytocin and phorbol 12-myristate 13-acetate (PMA) were purchased from Sigma (St. Louis, MO). BioMax films were from Eastman Kodak Corporation (New York, NY).
Preparation of Tissue, Isolation of Endometrial Cells, and Cell Culture
To study the differential production of prostaglandin, primary cultures of endometrial cells were used. Bovine uteri from early days of the estrous cycle (Days 1–5) were collected at the slaughterhouse within 15 min of death. Tissues were transported to the cell culture laboratory and the myometrium was dissected out, keeping the tubular structure of the endometrium. Endometrial epithelial and stromal cells were isolated successively by selective digestion with trypsin or trypsin-collagenase, respectively, as described previously [23]. In the present study, a total of 13 uteri from early cycles were used to generate 13 different cell preparations. The tissues were dated as described recently [24]. Endometrial epithelial and stromal cells were cultured separately and grown directly on the plastic surface of 24-well plates for all experiments except for the experiments aimed at RNA extraction, where 6-well plates were used. Medium (RPMI-1640 + 10% FBS-DC depleted of steroids by dextran-charcoal extraction) was changed every 2 days until the cells were treated. Confluence of cells occurred after 7–8 days in culture.
Characteristics of the Recombinant Ovine and Bovine IFN- Tested
Five recombinant IFN- proteins were selected among those previously produced, sequenced, and characterized [10, 12, 14–16, 20, 21, 25]. Three bovine (rb-1a, rb-2b, rb-3b) and two ovine (ro-4 and ro-11) IFN- were chosen for their different antiviral activities and potential to prolong the estrous cycle in vivo. The characteristics of the five IFN- isoforms are summarized in Table 1.
Experimental Protocol for Stimulation of Cells
After confluence, both epithelial and stromal cells were stimulated with each different isoform of IFN- in a concentration ranging from 0.01 to 20 µg/ml. For some experiments, cells were treated with OT (10-7 M) or PMA (10-7 M), alone or in addition to a rIFN- isoform. For prostaglandin measurement and protein extraction, three 2.0 cm2 wells were used per condition. For RNA isolation, two 9.6 cm2 wells were used per condition. Cells were then incubated in 5% CO2:95% air at 37°C for 24 h. For all experiments, at the end of incubation time, culture medium was recovered for PGE2 and PGF2 measurement and stored at -20°C until further processing. For RNA extraction, cells were lysed with TRIzol and stored at -80°C. For protein extraction, cells were lysed with 200 µl of lysis buffer (10 mM Tris-HCl, pH 7.4, 1% SDS, 1 mM dithiothreitol, and 1 mM PMSF) and extraction was done immediately.
Protein Extraction
Protein extraction and dosage were performed as described recently [26]. Protein samples were suspended in 25 µl SDS-PAGE loading buffer (0.06 M Tris-HCl, pH 6.8, 1% SDS, 1% 2-mercaptoethanol, 10% glycerol, and 0.025% bromophenol blue) and boiled for 3 min. Protein content was estimated using 1 µl of the sample.
Western Blot Analysis
Approximately 20-µg aliquots of total protein were loaded in each lane and electrophoresed through 10% SDS-polyacrylamide gels followed by electrotransfer onto nitrocellulose membrane. Prestained protein markers were used as molecular weight standard for each analysis. After staining with Ponceau Red to ensure that the same amount of proteins were transferred onto the membrane, the blocking was done in 5% fat-free dry milk powder in PBS and 0.05% Tween-20 (PBS-T) overnight at 4°C. The membrane was then incubated with the antibody raised against COX-2, lot no. 243, from Merck Frosst (Kirkland, QC, Canada) (dilution 1/3000 in 2% fat-free dry milk powder in PBS-T) for 1 h at room temperature. Washings were done for 30 min in PBS-T. The second antibody, goat anti-rabbit conjugated to horseradish peroxidase (dilution 1/10 000 in 2% fat-free dry milk powder in PBS-T) was then incubated for 45 min at room temperature. Membrane was washed for another 30 min in PBS-T. Bands were revealed by addition of a chemiluminescent substrate applied according to the manufacturer's instructions (Renaissance, NEN). The blots were exposed for 2 min to BioMax film with intensifying screen.
RNA Isolation
Total RNA was prepared and extracted using TRIzol reagent according to manufacturer's instructions. Endometrial cells were directly lysed in six-well plates with 0.8 ml per well. Cell lysates were stored at -80°C until further processing. RNA samples were suspended in water containing DEPC (0.05% v:v) and stored at -80°C. Before use, RNA was quantified by measurement of absorbance at 260 nm.
Northern Blot Analysis
The standard procedure for Northern blot analysis was used. Electrophoresis of 10 µg of total RNA was done in a formaldehyde gel and RNA was transferred onto a nylon membrane. The cDNA probe for bovine COX-2 was generated with specific primers (sense 5'-TCTTTGACTGTGGGAGGATACA-3' and antisense 5'-TCCAGATCACATTTGATTGACA-3'), labeled with DNA labeling kit (dCTP) and [32P] dCTP and purified by precipitation according to Chapdelaine et al. [27]. Prehybridization was performed at 45°C in UltraHyb solution for 4–5 h, then the labeled probe was added and hybridization was performed overnight at 45°C. Washings were done at room temperature two times for 5 min and at 68°C one time for 15 min in 2x SSC supplemented with 0.1% SDS and then two times for 15 min in 0.2x SSC supplemented with 0.1% SDS at 68°C. Signals were detected by autoradiography on BioMax film at -80°C (2-day exposure). Bands were quantified by image analysis using AlphaImager 2000 software (Alpha Innotech Corporation, San Leandro, CA). Intensity of each band was normalized to the intensity of corresponding 18S as seen on the gel.
ELISA for Prostaglandins
For PGE2 and PGF2 measurement, an ELISA was performed using acetylcholinesterase-linked PG tracers as described previously [28]. We have used fully characterized rabbit anti-PGE2 [28, 29] and sheep anti-PGF2 (Bio Quant, Ann Arbor, MI). The inter- and intraassay coefficients of variation (n = 12) were 16% and 10%, respectively.
Statistical Analysis
Data for PG levels are presented as the mean ± SEM. These data were treated by analysis of variance using Super ANOVA Software (Abacus Concepts Inc., Berkeley, CA). Sources of variation included experiments, treatments, and their interactions. Individual comparisons of means were made using the Student-Newman-Keuls test, where independent variables were the concentration and/or IFN- isoform tested and the dependent variable was the level of PGs produced. For Figures 1 and 2, data were analyzed within a concentration to highlight differences between isoforms and in a dose-response manner for each isoform. Differences were considered statistically significant when P < 0.05.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Isoforms on Prostaglandin Production in Epithelial Cells
The influence of different recombinant IFN- isoforms on PGE2 and PGF2 production was determined in epithelial cells and are illustrated in Figure 1. When we look at the pattern of response to the five different IFNs as a whole, low doses (<1 µg/ml) appear to inhibit both prostaglandin production, whereas at high doses (>1 µg/ml), some IFN- stimulate PGE2 production. However, each isoform exhibits a distinct dose-dependent response: isoforms rb-2b and ro-4 inhibit PGE2 (Fig. 1A) and PGF2 (Fig. 1B) production at almost all doses tested (P < 0.05). IFN rb-1a stimulates PGs at high concentrations (10 and 20 µg/ml) and ro-11 inhibits PGE2 at low concentrations (<1 µg/ml) and stimulates both PGs at high concentrations (>1 µg/ml). Interestingly, PGE2 is stimulated preferentially, thus increasing its production relative to PGF2. Isoform rb-3b inhibits PGE2 at all concentrations tested and had variable non-dose-dependent effects on PGF2.
Effect of Five rIFN- Isoforms on Prostaglandin Production in Stromal Cells
The influence of the different IFN- isoforms on PG production was also determined in stromal cells (Fig. 2). The pattern of response as a whole appears once again biphasic, i.e., no response or inhibition at low doses (<1 µg/ml) and stimulation at high doses (20 µg/ml). However, as was observed in epithelial cells, each isoform exhibits a distinct dose-dependent response. Isoforms rb-2b and rb-3b inhibit (P < 0.05) or have no effect on PGE2 (Fig. 2A) and PGF2 (Fig. 2B) production at all doses tested. IFNs rb-1a and ro-11 stimulate both PGs at high concentrations (>1 µg/ml). Isoform ro-4 exhibits a response clearly distinct from what was observed in epithelial cells. In stromal cells, it has no effect at low concentration and a stimulatory effect on both PGs at high concentration (P < 0.05). In contrast with epithelial cells, the effect of all IFNs is identical on PGE2 and PGF2. However, the primary PG produced in this cell type remains PGE2, a consistent discriminating characteristic of stromal cells.
Effect of Different rIFN- Isoforms on COX-2 Induction in Epithelial Cells
Three isoforms of IFN- were selected to study the effect on the expression of COX-2 protein. Two were selected for their high induction of PGE2 production and no PGF2 stimulation (isoforms rb-1a and ro-11) and one for its inhibition of both PGE2 and PGF2 production (isoform rb-2b). As shown in Figure 3A, COX-2 protein is induced with isoform ro-11 at 20 µg/ml and isoform rb-1a at 0.05 µg/ml and 20 µg/ml. No induction is seen with isoform rb-2b or with lower doses of isoform ro-11. The five rIFN- isoforms were used to study their effect on COX-2 mRNA expression by Northern blot analysis (Fig. 3B); almost all rIFN- isoforms stimulate COX-2 mRNA at maximal dose (20 µg/ml). Isoform ro-11 clearly induces COX-2 expression, followed by rIFN- ro-4 > rb-1a = rb-3b > rb-2b.
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Effect of Different rIFN- Isoforms on Prostaglandin Production in Presence of PMA in Epithelial Cells
The effect of IFN- was tested in the presence of PMA, a known inducer of PG production and COX-2 expression (Fig. 4). When only PMA is given to the cells, an increase in the production of PGE2 is observed, reaching a 12-fold induction compared with the control (as shown in Fig. 1) (P < 0.05). PGF2 production is not influenced significantly by PMA (P > 0.05). When the different IFNs are added in the presence of PMA, the production of both PGE2 and PGF2 is reduced by all isoforms following a similar pattern (P < 0.05). At high concentrations of isoforms rb-1a, ro-11, and ro-4, there is a reversal of the inhibition response (P < 0.05). Interestingly, the reversal is observed with the same isoforms that induce a stimulation of PGE2 at high concentrations in the absence of PMA (as shown in Fig. 1).
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Effect of Different rIFN- Isoforms on Prostaglandin Production and COX-2 Protein in the Presence of Oxytocin in Epithelial Cells
The effect of OT on PG production alone or in combination with different isoforms of IFN- is illustrated in Figure 5. First, we observe that OT induces a significant 13-fold increase in PGF2 production (P < 0.05) compared with non-stimulated cells (as shown in Fig. 1) and no significant increase in PGE2 production (P > 0.05). This pattern of response is the exact opposite of PMA illustrated in Figure 4. For all isoforms tested, there is no effect on PGE2 production. A significant dose-dependent decrease in the production of PGF2 (P < 0.05) was observed for all IFNs tested excepted rb-1a, where the inhibition was the same at all concentrations. In parallel, the effect of IFNs on COX-2 protein was determined in the presence of OT (Fig. 6). First, we observe that OT induces the expression of COX-2 protein within the 24-h stimulation period. Second, the presence of rIFN- at 20 µg/ml reduces the expression of COX-2 protein for all isoforms tested.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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is recognized as the conceptus signal responsible for recognition of pregnancy. The IFN- peptides produced in ovine and bovine appear similar in structure and activity. Indeed, both can prolong the cycle in the absence of a viable conceptus in heterologous species [30] and increase PGE2 production [31] and COX-2 expression [18] in vitro. The present study confirms, with five different isoforms, that ovine and bovine rIFN- can modify prostaglandin production, modulate COX-2 expression, and express antiviral activity. IFNs tested were selected for their distinctive characteristics described in previous publications and summarized in Table 1. The different isoforms do not show the same antiviral activity (Table 1). The IFN- tested exhibited distinct dose-dependent effects on prostaglandin production (Figs. 1 and 2) and COX-2 induction (Fig. 3). There is no apparent relation between their antiviral activity and the capacity to modulate PG production or COX-2 induction.
When the effect of the different IFN- isoforms is taken individually, we find that every isoform is able to inhibit prostaglandin production at low doses (Figs. 1 and 2). However, at high doses, only a few are able to increase PGE2 production. This suggests that the mechanisms leading to stimulation or inhibition of PG production are mediated by different receptors or different states of the receptor. If we consider the absence of correlation with antiviral activity, the story becomes even more complex. If only one type of receptor was involved, the mass action law applied to ligand-receptor interactions as described by Berson and Yalow [32] would suggest that related agonists with different affinities for the same receptor would induce a similar pattern of response with a leftward or rightward shift on the dose response axis. The results of the present study suggest that, if there are two receptors, the different isoforms of IFN- have distinct affinities for each receptor. At present, it remains to be determined whether there is a unique IFN- receptor in the endometrium [33]. The ability of IFN- to stimulate or inhibit PG production and the resulting conflicting reports in the literature may depend on the presence of multiple forms of receptors for IFN- [34] coupled to distinct transduction pathways [35, 36].
When we look at the overall pattern of response to the five IFNs tested, we observe a biphasic effect on prostaglandin production. At low doses (<1 µg/ml), an inhibition of production of both prostaglandins is observed, and at high doses (>1 µg/ml), the production of PGE2 in epithelial cells and both PGs in stromal cells are increased. In the latter cell type, it should be stressed that the production of PGE2 is 10-fold higher; therefore, if we look at the effect on the two cell types, we observe a net increase in the production of PGE2 at high concentrations of IFN-. Others have shown an inhibitory effect of IFN- on prostaglandin production at low doses [37, 38]. The biphasic effect of rIFN- in vitro may have physiological relevance in vivo, as the local concentration of IFN- in the uterus is likely to increase during elongation and growth of the conceptus.
Those IFN- isoforms able to stimulate PGE2 production (Fig. 1) also increased COX-2 expression (Fig. 3). We have reported previously that roIFN- induced COX-2 but not COX-1 expression and that inhibition of COX-2 with the specific inhibitor NS-398 blocked IFN--induced PGE2 stimulation [18]. Others have demonstrated that rbIFN- could also decrease prostaglandin F synthase (PGFS) mRNA, thus providing an alternate mechanism to increase the PGE2/PGF2 ratio [39]. Others again have suggested that IFN- acts by inhibition of COX-2 gene transcription [40]. However, in that study, only PGF2 and not PGE2 production was measured in the bovine endometrial cell line BEND. It demonstrated an inhibition of PGF2 following treatment with 50 ng/ml rIFN-, a concentration much lower than the maximal concentration used here, which at 20 µg/ml is, however, within the physiological range. When we compare their results with what we observe at 50 ng/ml on PGF2 production (Figs. 1 and 2) and COX-2 expression (Fig. 3A), the conclusions are very similar. The present study confirms with new isoforms of rIFN- our previous observation that high doses of IFN- stimulate COX-2 mRNA, but it is further supported by our finding of an increased COX-2 protein expression.
The effect of rIFN- on epithelial cells is slightly different when determined in the presence of agents that stimulate PG production. First, it is interesting to note that PMA and OT have distinct effects on the production of PG by epithelial cells. The former specifically increases PGE2 production, whereas the latter stimulates only PGF2. Because both agents are known to increase COX-2 expression, their selective action must rely on enzyme pathways downstream of COX and responsible for the generation of specific types of PG. Alternatively, PMA and OT may act on distinct pools of arachidonic acid and COX-2 coupled with specific PG pathways. This hypothesis is supported by our observation that, in the presence of PMA, the different IFN- inhibited only PGE2 at all concentrations tested and, in the presence of OT, they inhibited only PGF2. The pattern of inhibition of each isoform is different, with partial reversion of inhibition at high concentrations of those isoforms (rb-1a, ro-11, and ro-4) that stimulated PGE2 production in the absence of PMA. This suggests interaction at the level of intracellular mechanisms used by PMA and IFN- for the regulation of PGE2. Another study has already reported that the effect of PMA on PGF2 synthesis and COX-2 protein was reduced when the cells were treated with IFN- [41]. In the presence of OT, in contrast with PMA, there is a dose-dependent decrease in PGF2 production and no reversal of inhibition at high doses (Fig. 5). Because OT and IFN- were added to the cells at the same time, it is unlikely that the observed effect of IFN- was due to a change in OT receptors. We can suppose that there is interference between intracellular signals or a competition at the receptor level between IFN- and OT. However, it has already been demonstrated that there is no competition between those two compounds for a receptor [42], but it has been suggested that there are some interactions between IFN- and OT at the cellular level in the regulation of PGs production [43]. Another study suggested that the inhibitory effect of IFN- on OT-induced PGF2 production is not only attributable to a decrease in OT receptor but also to down-regulation of COX-2. Indeed, activation of protein kinase C by PMA bypasses the interaction of OT with its receptor [41]. In the present study, both IFN- and OT were able to increase COX-2 protein, but when added at the same time, COX-2 protein was decreased by maximal doses of rIFN- compared with OT alone. This is in agreement with the study of Xiao et al. [41], where both COX-2 mRNA and protein were decreased following stimulation with rIFN- in the presence of OT. Apparently, activation of PG production with OT or PMA induces an alteration in the response to IFN-, limiting their action to inhibition of PG production. This may suggest that PMA and OT alter the properties of IFN receptors or their downstream regulators.
As reported previously, the five IFN- isoforms tested in the present study exhibit different antiviral activities (Table 1). It has been demonstrated that more than 99% of the antiviral activity released by bovine conceptus is attributable to trophoblast IFN [22]. Several isoforms of bovine IFN- are expressed by the developing bovine conceptus between Days 14 and 25 of pregnancy. The different isoforms of ovIFN- vary in their ability to extend CL lifespan in nonpregnant cows [10, 11]. Among the isoforms tested in the present study, isoform ro-4 exhibited the broadest cross-species antiviral reactivity [17], isoforms rb-1a and rb-2b were found equally potent, whereas the rb-3b protein had significantly lower antiviral activity [10]. The results presented in this study do not show any clear correlation between antiviral activity, PG production, and COX-2 induction.
In summary, the present study describes the effect of five different isoforms of rIFN- on bovine endometrial cells. In endometrial cells, high concentrations of IFN- clearly stimulate PGE2 production or increase its production relative to PGF2. Isoforms that stimulate PGE2 production also induce COX-2 expression. When endometrial cells are stimulated with PMA or OT to increase the production of PGs, IFNs loose their ability to stimulate PG production at high doses but maintain their ability to inhibit it at all doses. This suggests the presence of more than one receptor or state of receptor for IFN-. However, this study failed to establish a clear correlation between antiviral activity and regulation of prostaglandin production. Altogether, these results suggest that, if the action of IFN- on endometrial cells in vitro reflects the effect on the same cells in vivo, the mechanisms leading to recognition of pregnancy may not be limited to inhibition of OT action on PGF2 production.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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2 Correspondence: M.A. Fortier, Ontogénie et Reproduction, Centre de Recherches du Centre Hospitalier Universitaire de Québec (CHUL), 2705 boulevard Laurier, Ste-Foy, QC, Canada G1V 4G2. FAX: 418 654 2765; e-mail: mafortier{at}crchul.ulaval.ca
Received: 17 July 2002.
First decision: 23 August 2002.
Accepted: 7 October 2002.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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secretion at luteolysis in ruminants. Domest Anim Endocrinol 1990 7:111-124[CrossRef][Medline]. J Interferon Cytokine Res 2000 20:817-822[CrossRef][Medline] genes: relative transcript abundance during early placental development, promoter sequences of genes and biological activity of protein products. Endocrinology 2001 142:2906-2915 (IFN-). Changes in receptor binding and in antiviral and antiproliferative activities resulting from site-directed mutagenesis performed near the carboxyl terminus. J Biol Chem 1994 269:24826-24833 in Escherichia coli. Protein Expr Purif 1995 6:401-407[CrossRef][Medline] subtypes on bovine, murine, and human cells: contradictory evidence for therapeutic potential. J Interferon Cytokine Res 1999 19:1335-1341[CrossRef][Medline] increases PGE2 production and COX-2 gene expression in the bovine endometrium in vitro. Mol Cell Endocrinol 1997 132:117-126[CrossRef][Medline]II. Mol Endocrinol 1989 3:127-139[Abstract] and E2 and response to oxytocin in cultured epithelial and stromal cells of the bovine endometrium. Biol Reprod 1996 54:371-379[Abstract] suppresses prostaglandin F2 secretion independently of the mitogen-activated protein kinase and nuclear factor 
B pathways. Biol Reprod 2001 64:965-973 stimulates the janus kinase-signal transducer and activator of transcription pathway in bovine endometrial epithelial cells. Biol Reprod 2001 64:654-665 in bovine endometrial cells. Endocrinology 1998 139:2293-2299This article has been cited by other articles:
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