Abstract
In this study, we investigated the expression of mucin 1 (MUC1) mRNA and protein in sheep endometrium at different time points during follicular and luteal phases of estrous cycle, and also determined the effect of steroid hormone treatments and interferon tau (IFNτ) on MUC1 mRNA expression in endometrial cell culture in vitro. In experiment one, 15 Welsh mountain ewes were synchronized to a common estrus and killed at precise stages of estrous cycle corresponding to (1) pre-LH peak, (2) LH peak, (3) post-LH peak, (4) early luteal, and (5) mid-luteal. Reproductive tracts were harvested and mRNA was extracted from the endometrial tissues. Parts of the uterine horns were fixed for immunohistochemistry. In experiment two, mixed populations of ovine endometrial cells (from slaughterhouse material collected at the postovulatory stage of the estrous cycle) were cultured to 70% confluence before treatment with (1) progesterone (P4, 10 ng/mL, for 48 hours), (2) estradiol (E2, 100 pg/mL, for 48 hours), or with (3) E2 priming for 12 hours (100 pg/mL) followed by P4 (10 ng/mL) for 36 hours. These were compared with: (4) IFNτ (10 ng/mL, for 48 hours), and (5) basic medium (Dulbecco Modified Eagle Medium /F12) as control. The results showed that MUC1 mRNA and protein expression in sheep endometrium were highest during the midluteal stage and very low during the post-LH period compared with the other stages (P < 0.05). MUC1 immunostaining in the luminal epithelium was apically restricted and was not significantly different across all stages of estrous cycle except at the post-LH peak where it was significantly low. In cell culture, MUC1 mRNA expression was significantly upregulated by both steroids either singly or in combination (P < 0.05), and downregulated in the presence of IFNτ. In conclusion, endometrial MUC1 expression is cyclically regulated by both E2 and P4in vivo and in vitro, and directly downregulated by IFNτ treatment in vitro.
Highlights
Mucin 1 (MUC1) is a membrane-bound O-glycosylated protein that is a member of the mucin family.It is expressed on the apical surface of mucosal epithelial cells and plays an essential role in forming protective mucous barriers on epithelial surfaces and is involved in intracellular signalling
The results showed that MUC1 mRNA and protein expression in sheep endometrium was highest during the mid-luteal stage and very low during the post-LH period compared with other stages (P
We have investigated the temporal variation of MUC1 mRNA and protein expression in sheep endometrium during different stages of estrous cycle
Summary
Mucin 1 (MUC1) is a membrane-bound O-glycosylated protein that is a member of the mucin family. It is expressed on the apical surface of mucosal epithelial cells and plays an essential role in forming protective mucous barriers on epithelial surfaces and is involved in intracellular signalling. MUC1 is expressed in the uterus [1] and in the testes [2]. Successful implantation requires complex interaction between trophoblast and maternal endometrium. Non-receptivity of endometrium has been partly attributable to features characteristic of luminal epithelia expressing glycocalyx, of which trans-membrane mucin 1 glycoprotein encoded by MUC1 gene is the most widely expressed and distributed in the reproductive tract [3]
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