Progesterone and interferon-tau regulate cystatin C in the endometrium

Area of Science:

• Reproductive Biology
• Molecular Endocrinology
• Uterine Physiology

Background:

• Cystatin C (CST3) inhibits cathepsins, enzymes vital for implantation and placentation in mice.
• Cathepsins B (CTSB) and L (CTSL) are present in the ovine endometrium and conceptus.

Purpose of the Study:

• To investigate the regulation of CST3 expression in the ovine uterus during the estrous cycle and pregnancy.
• To determine the effects of progesterone (P4) and interferon-tau (IFNT) on CST3 expression in ewes.

Main Methods:

• Quantitative real-time PCR (qPCR) to measure CST3 mRNA levels in endometrial tissues.
• Western blotting to detect CST3 protein expression.
• Analysis of CST3 in uterine flushes from cyclic and pregnant ewes.
• Hormonal treatments in ovariectomized ewes using P4, IFNT, and an antiprogestin (ZK 136,317).

Main Results:

• CST3 mRNA expression significantly increased during the estrous cycle (d 10-12) and early pregnancy (d 10-20) in ewes.
• CST3 mRNA and protein were localized to the endometrial luminal and glandular epithelium and conceptus trophectoderm.
• CST3 protein was detected in uterine flushes from pregnant ewes from d 12 onwards.
• Progesterone treatment robustly increased endometrial CST3 mRNA, with IFNT providing a further modest stimulation.
• Antiprogestin treatment abolished P4-induced CST3 expression, indicating P4's essential role.

Conclusions:

• CST3 is a novel gene regulated by progesterone and stimulated by interferon-tau in the ovine endometrium.
• CST3 expression is temporally and spatially regulated during the estrous cycle and pregnancy.
• CST3 likely plays a significant role in modulating uterine cathepsin activity essential for conceptus implantation in sheep.