Uterine Cellular Changes in 2′,5′-Oligoadenylate Synthetase during the Bovine Estrous Cycle and Early Pregnancy1

Abstract

The signal for maternal recognition of pregnancy in cattle is bovine trophoblast protein-1 (bTP-1), a Type I trophoblast interferon. One of the many functions of interferons is the induction of the 2',5'-oligoadenylate (2-5[A]) system, which is involved in cell division and selective degradation of mRNA. The present study focused on the cellular changes of 2-5(A) synthetase in bovine endometrium during the estrous cycle and early pregnancy. Ability of recombinant bTP-1 to stimulate activity of the enzyme in uterine cells throughout the estrous cycle was also evaluated in vitro. Surface epithelium, glandular epithelium, and stroma were enzymatically separated in cows on Day 5, 10, 15, or 18 postestrus and on Day 15 or 18 of pregnancy. Cell samples were lysed and frozen for determination of the endogenous cellular content of 2-5(A) synthetase. Additional cells obtained during the estrous cycle were cultured and treated with increasing doses of recombinant bovine interferon alpha (rbIFN-alpha) or recombinant bTP-1 (rbTP-1). During the estrous cycle, 2-5(A) synthetase was greatest on Day 5 and declined approximately 10-fold by Day 15 (p < 0.01). Cellular content of 2-5(A) synthetase was similar among all three endometrial cell types. In the gravid horn of pregnant animals, presence of a conceptus significantly increased (p < 0.01) 2-5(A) synthetase in all endometrial cell types compared to levels on Days 15 and 18 of the estrous cycle. On Day 18, levels of 2-5(A) synthetase were 30-fold greater (p < 0.01) in epithelium (surface and glandular) from pregnant cows compared to that from cyclic cows.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcriptomic Analysis of the Bovine Endometrium: What is Required to Establish Uterine Receptivity to Implantation in Cattle ?

“…Testing this hypothesis revealed that pregnancy and IFNT induced the production of uncharacterised proteins by the endometrium [17]. Some of these proteins and genes induced by pregnancy/IFNT were later revealed to be classical Type I IFN stimulated genes (ISGs) 2',5'-oligoadenylate synthetase 1, 40/46 kDa; OAS1 [18,19] With the widespread availability of large-scale transcriptomic analysis, the molecular mechanisms required to establish uterine receptivity to implantation and pregnancy recognition are beginning to be elucidated. The initial in vivo analysis of the effect of the conceptus on endometrial gene expression was carried out using subtracted cDNA libraries [28] and a model of monozygotic twins to reduce genetic variation.…”

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

“…Additionally, in cultured bovine uterine cells a dose dependent stimulation of 2´-5´-oligoadenylate synthase by IFNτ could be observed (Schmitt et al, 1993).…”

“…Some of these genes have already been described in the context of early pregnancy in ruminants, e.g. ISG15 (Austin et al, 1996;Johnson et al, 1998;Austin et al, 2004) OAS1 (Schmitt et al, 1993), IRF1 , IFITM1 and IFITM3 (Pru et al, 2001), MX protein Hicks et al, 2003), IFIT1 , ISG12 , MHC class I genes and B2M , but only little information exists concerning the putative roles of these ISGs in the context of early pregnancy.…”

“…Thereby this enzyme family plays a role in viral infection resistance by degrading viral RNAs (Dong and Silverman, 1995). Concerning reproductive processes, the 2', 5'-oligoadenylate synthetase is hypothesized to affect PGF 2α secretion by the endometrial epithelium, possibly by altering arachidonic acid metabolism (Schmitt et al, 1993).…”

Função do interferon-tau durante o reconhecimento materno da gestação em ruminantes

“…Esses complexos se ligam a regiões definidas no DNA chamadas de elementos responsivos à estimulação por interferons (ISREs) que regulam a expressão de ISGs (HANSEN et al, 1999). Dentre os ISGs que aumentam sua expressão durante o início da gestação em resposta ao IFNT, estão o 2',5' oligoadenilato sintetase (OAS; MIRANDO et al, 1991;SCHMITT et al, 1993;JOHNSON et al, 2001), o gene de resistência ao myxovirus 1 (MX1; (OTT et al, 1998) e o gene estimulado pelo interferon 15 (ISG15; NAIVAR et al, 1995;AUSTIN et al, 1996;JOHNSON et al, 1999). Estudos recentes demonstraram a expressão de ISGs em células do sangue (YANKEY et al, 2001;HAN et al, 2006;GIFFORD et al, 2007) e CL (OLIVEIRA et al, 2008;BOTT et al, 2010) logo após a sinalização por IFNT no início da gestação em ruminantes.…”