Inhibitors of apoptosis: expression and regulation in the endometrium during the estrous cycle and at the maternal-conceptus interface during pregnancy in pigs

Abstract

Objective: Caspase-mediated apoptosis plays a crucial role in the regulation of endometrial and placental function in females. Caspase activity is tightly controlled by members of the inhibitors of apoptosis proteins (IAPs) family. However, the expression and regulation of IAPs at the maternal-conceptus interface has not been studied in pigs.Therefore, we determined the expression of IAP family members BIRC1 (baculovirus IAP repeat-containing 1) to BIRC6 at the maternal-conceptus interface in pigs. Methods:We obtained endometrial tissues from pigs at various stages of the estrous cycle and pregnancy, conceptus tissues during early pregnancy, and chorioallantoic tissues during mid-to late pregnancy and analyzed the expression of IAPs. Furthermore, we determined the effects of the steroid hormones estradiol-17β (E2) and progesterone on the expression of IAPs in endometrial explant tissue cultures.Results: During the estrous cycle, BIRC2 and BIRC5 expression varied cyclically, and during pregnancy, endometrial BIRC1, BIRC2, BIRC3, BIRC4, and BIRC5 expression varied in a stage-specific manner. Conceptus and chorioallantoic tissues also expressed IAPs during pregnancy. The BIRC2 and BIR3 mRNAs were localized to luminal epithelial cells, and BIRC4 proteins to glandular epithelial cells in the endometrium. Exposure of endometrial tissues to E2 increased the expression of BIRC6, while progesterone increased the expression of BIRC1, BIRC4, and BIRC6 in a dose-dependent manner.Conclusions: These results indicated that IAPs were expressed in the endometrium during the estrous cycle and at the maternal-conceptus interface during pregnancy in a stagespecific manner. In addition, steroid hormones were found to be responsible for the expression of some IAPs in pigs. Together, the results suggested that IAPs may play important roles in endometrial and placental functions by regulating caspase action and apoptosis at the maternal-conceptus interface.

Conceptus-derived cytokines interleukin-1β and interferon-γ induce the expression of acute phase protein serum amyloid A3 in endometrial epithelia at the time of conceptus implantation in pigs

“…Endometrial tissues dissected free of myometrium and collected from the middle portion of each uterine horn, conceptus tissues obtained in uterine flushings and washed with PBS (pH 7.4), and chorioallantoic tissues were snap-frozen in liquid nitrogen and stored at −80°C prior to RNA extraction. For in situ hybridization, cross-sections A c c e p t e d A r t i c l e of endometrium were fixed in 4% paraformaldehyde in PBS (pH 7.4) for 24 h and then embedded in paraffin, as previously described [20].…”

“…To determine the effects of estradiol-17β (E2), progesterone (P4), and IL1B on the expression of SAA3 mRNA in the endometrium, endometrial explant tissues obtained from gilts on Day 12 of the estrous cycle were cultured as previously described [20]. Endometrium dissected from the myometrium was placed into warm phenol red-free Dulbecco's modified Eagle's medium/F-12 culture medium (DMEM/F-12; Sigma, St. Louis, MO) containing penicillin G (100 IU/mL) and streptomycin (0.1 mg/mL).…”

“…The SCNT technique is a valuable tool for producing genetically valuable or transgenic animals for basic and biomedical use in animal biotechnology, but the high rates of embryonic mortality and pregnancy failure lead to low efficiency in generating viable cloned animals [20].…”

“…Although the exact cause of low efficiency in SCNT cloning is being investigated, it is thought to be associated with abnormal embryonic reprogramming and inappropriate maternalconceptus interactions at the maternal endometrium [20]. Our previous studies have shown that in endometria with SCNT-derived conceptuses, many genes are abnormally expressed during early pregnancy [16,17,32].…”

Analysis of cellular communication network factor (CCN) 4 and CCN6 expression in the endometrium during the estrous cycle and at the maternal-conceptus interface in pigs

“…Endometrial tissue, dissected free of myometrium, was collected from the middle portion of each uterine horn, snap-frozen in liquid nitrogen, and stored at -80℃ prior to RNA extraction. For in situ hybridization and immunohistochemistry, cross-sections of endometrium were fixed in 4% paraformaldehyde in PBS (pH 7.4) for 24 h and then embedded in paraffin as previously described (Yoo et al, 2022).…”