Expression of the uterine Mx protein in cyclic and pregnant cows, gilts, and mares1,2

Abstract

Pregnancy and interferon-tau (IFN tau) upregulate uterine Mx gene expression in ewes; however, the only known role for Mx is in the immune response to viral infection. We hypothesize that Mx functions as a conceptus-induced component of the anti-luteolytic mechanism and/or regulator of endometrial secretion or uterine remodeling during early pregnancy. This study was conducted to determine the effects of early pregnancy on uterine Mx expression in domestic farm species with varied mechanisms of pregnancy recognition. Endometrium from cows, gilts, and mares was collected during the first 20 d of the estrous cycle or pregnancy, and total messenger RNA (mRNA) and protein were analyzed for steady-state levels of Mx mRNA and protein. Northern blot analysis of Mx mRNA detected an approximately 2.5 Kb of mRNA in endometrium from each species. In pregnant cows, steady-state levels of Mx mRNA increased 10-fold (P < 0.05) above levels observed in cyclic cows by d 15 to 18. In cyclic gilts, slot blot analysis indicated that endometrial Mx mRNA levels did not change between d 5 and 18 of the cycle. However, in pregnant gilts, Mx levels tended (P = 0.06) to be elevated two-fold on d 16 only, and in situ hybridization indicated that this increase occurred in the stroma. In mares, Mx mRNA was low, but detectable, and did not change between ovulation (d 0) and d 20, regardless of reproductive status. Western blot analysis revealed multiple immunoreactive Mx protein bands in each species. One band was specific to pregnancy in cows. As in ewes, in situ hybridization analysis indicated that Mx mRNA was strongly expressed in the luminal epithelium, stroma, and myometrium by d 18 in cows. However, on d 14 in gilts, Mx was expressed primarily in the stroma, and on d 14 in mares, low levels of Mx expression were confined largely to the luminal epithelium. The uteruses of cows, gilts, and mares express Mx, and expression is upregulated during pregnancy in cows and gilts--animals whose conceptuses secrete interferons during early pregnancy, but that possess different mechanisms for pregnancy recognition.

Maternal-embryo interaction leading up to the initiation of implantation of pregnancy in cattle

“…In general, these differences are detectable by Day 15 or Day 16 of pregnancy (Forde et al, 2011b;Bauersachs et al, 2012) and the major changes identified include response to a Type I Interferon, of which IFNT is one. This includes the up-regulation of 'classical' interferon-stimulated genes (ISGs) such as ISG15, (Johnson et al, 1998), MX1 and MX2 (Hicks et al, 2003), OAS1, BST2, B2M, CXCL10, STAT1, STAT2, PTX3, EIF4E, USP18 (Forde et al, 2011b) Indeed in the last number of years there have been quite a number of large transcriptomic studies performed on gene expression changes in the endometrium of pregnancy compared with non-pregnant or cyclic heifers. Despite the different platforms used for analysis, breed of animal and different data analysis methods Bauersachs et al (2012) used gene set enrichment analysis to reveal a conceptus-induced signature in the endometrium across numerous studies on Days 15, 16, 17, 18 and 20.…”

2 Identification of Genes Induced by the Conceptus in the Bovine Endometrium During the Pre-Implantation Period

“…In contrast GM-CSF gene expression was readily stimulated in stromal cells (Emond et al, 2000). Granulocyte chemotatic protein-2, a member of the alpha-chemokine family is also released by cultured endometrial cells in response to IFNτ (Teixeira et al, 1997;Staggs et al, 1998 as during early pregnancy in both endometrium and myometrium Hicks et al, 2003), where steady-state levels of Mx mRNA increase 10-fold above levels observed in cyclic cows by day 15 to 18.…”

Exogenous hormonal manipulation to increase reproductive efficiency in dairy cows

“…Despite the links between progesterone concentrations during early diestrus and fertility in dairy cows as observed in the current study and demonstrated by others (PARR et al, 2012), increasing concentrations by almost 2 ng/mL in CIDR4 and CIDR4+7 cows compared with controls did not result in increased P/AI or reduced pregnancy loss. Mann and Lamming (1999) effects on the endometrium, but also effects on cells in other tissues (HICKS et al, 2003;GIFFORD, 2010). Interferon-τ exits the uterus and reaches the maternal circulation (Oliveira et al, 2008), which induces expression of genes in blood leukocytes (GIFFORD et al, 2008;OLIVEIRA et al, 2008).…”

“…The absence of oxytocin receptor in the endometrium prevents the release of luteolytic pulses of PGF, thereby sustaining lifespan of the CL and P4 production (DORNIAK;SPENCER, 2013). In addition to preventing luteolysis, IFN also induces expression of a large number of IFN stimulated genes (ISGs) in the endometrium (HICKS et al, 2003;GIFFORD et al, 2008). Not only endometrial cells express ISGs, but also other tissues, such as peripheral blood mononuclear cells (PBMC).…”

“…The down-regulation of oxytocin receptors ultimately inhibits pulsatile release of PGF2α responsible for the demise of the CL (MEYER et al, 1995;SPENCER et al, 2007). Production of IFN-τ by the conceptus induces IFN-stimulated genes (ISG) in the endometrium such as myxovirus (influenza virus) resistance 1 (Mx1) and receptor transporter protein 4 (RTP4; HICKS et al, 2003;GIFFORD et al, 2008). Blood leukocytes harvested on d 16 or 19 after AI had increased expression of the ISG ubiquitin-like IFNstimulated gene 15-kDa protein (IGS15), Mx1, Mx2, and RTP4 (GIFFORD et al, 2007;, and leukocyte mRNA for ISG was correlated with the amount of IFN-τ in the uterus (MATSUYAMA et al, 2012).…”