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EXPRESSION OF THE UTERINE MX PROTEIN IN THE CYCLIC AND PREGNANT COW, GILT, AND MARE.
Hicks, Brady 1, Yankey, Stephanie1, Carnahan, Kevin1, Assiri, Abdullah2, Sinor, Stacy1, Kodali, Kiran1, Vanderwall, Dirk1, Woods, Gordon1, Mirando, Mark2, Ott, Troy1, 1 2
ABSTRACT- Pregnancy and interferon-tau (IFN) up regulate uterine Mx gene expression in ewes, however, the only known role for Mx is in the IFN regulated immune response to viral infection. We hypothesize that Mx functions as a conceptus-induced component of the antiluteolytic mechanism and/or regulator of endometrial secretion in the uterus. This study determined the effect of early pregnancy on Mx expression in domestic farm species with varied mechanisms of pregnancy recognition. Uterine endometrium from cows, gilts and mares was collected during the first 20 days of the estrous cycle or pregnancy (4 animals/day/status), and total mRNA and protein were analyzed for steady-state levels of Mx by Western, Northern and slot-blot hybridization. Northern blot analysis detected a 2.5 Kb message in endometrium of each species. In addition, 2 minor hybridizing bands (4.3 and 1.7 Kb) were detected in the pregnant ewe and 3 minor bands (9.3, 4.3 and 1.7 Kb) were detected in pregnant cows. In the pregnant cow, where IFN is the signal for pregnancy recognition, steady-state levels of Mx mRNA increased above levels observed in cyclic cows (10-fold increase, p <.05) by D15-18. In the gilt, which utilizes conceptus estrogen for pregnancy recognition but whose conceptuses also produce 2 forms of interferon during early pregnancy, endometrial Mx mRNA did not change between D5 and 18 of the cycle. In pregnant gilts, Mx levels were elevated (2-fold increase, p=.06) on D16 only. In the mare, where little is known about the mechanism for pregnancy recognition and whose conceptuses do not secrete IFN, Mx mRNA did not change between D0 (ovulation) and 20, regardless of reproductive status. Western Blot analysis using carboxyl and amino terminal polyclonal anti-peptide antisera against ovine Mx revealed a temporal pattern of Mx protein that was similar to that seen for Mx mRNA for each species. Multiple immuno-reactive Mx protein bands were observed in each of these species, one of which was specific to pregnancy in the cow and ewe. These results indicate that Mx is expressed in the uterus of the cow, gilt and mare, and is up-regulated by pregnancy in ruminants and pigs, which express conceptus-secreted interferon, but have different mechanisms for pregnancy recognition. Supported in part by USDA-CSREES-NRI grant 96-35203-3916 to TLO.
KEY WORDS: Mx, interferon, uterus, pregnancy
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