Circulating miRNAs in maternal plasma as potential biomarkers of early pregnancy in sheep.

MicroRNA (miRNA) plays an important role in the control of gene expression and is implied in many biological functions, including embryo implantation and development. The aim was to assess plasma miRNA profiles during the peri-implantation and ascertain potential candidate miRNA markers for early pregnancy diagnosis in ovine plasma. The plasma samples were obtained from a total of 24 ewes on days 12 (pre-implantation; P12, n = 4), 16 (implantation; P16, n = 4) and 22 (post-implantation; P22, n = 4) after mating, and on their corresponding days of 12 (Pre-C; C12, n = 4), 16 (Imp-C; C16, n = 4) and 22 (Post-C; C22, n = 4) of the estrous cycle. The miRNA profiles in plasma were assessed by microarray technology. We detected the presence of 60 ovine-specific miRNAs in plasma samples. Of these miRNAs, 22 demonstrated a differential expression pattern, especially between the estrous cycle and early pregnancy, and targeted 521 genes. Two miRNAs (oar-miR-218a and oar-miR-1185-3p) were confirmed using RT-qPCR in the ovine plasma samples. Protein-protein interaction (PPI) network of target genes established six functional modules, of which modules 1 and 3 were enriched in the common GO terms, such as inflammatory response, defense response, and regulation of immune response. In contrast, module 2 was enriched in the developmental process involved in reproduction, embryo development, embryonic morphogenesis, and regulation of the developmental process. The results indicate that miRNAs profiles of plasma seemed to be modulated during the peri-implantation stage of pregnancy in ewes. Circulating miRNAs could be promising candidates for diagnosis in early ovine pregnancy.

Expression pattern of microRNAs in ovine endometrium during the peri-implantation.

MicroRNA (miRNA), acting as the transcriptional regulator of gene expression, has been widely demonstrated to be involved in many biological functions, including embryo implantation and development. The objective of the current study was to illuminate the expression pattern of microRNAs (miRNAs) in the endometrium during the peri-implantation in ewes. Intercaruncular endometrial samples was obtained from a total of 24 ewes on days of 12 (pre-implantation, n = 4), 16 (implantation, n = 4) and 22 (post-implantation, n = 4) of pregnancy following mating, and on their corresponding days of 12 (n = 4), 16 (n = 4) and 22 (n = 4) of the estrous cycle. The miRNA profiles were examined in the endometrium by microarray technology. We detected 116 ovine specifics miRNAs in the endometrium. Of these, nineteen were differentially expressed in early pregnancy. Four miRNAs (oar-miR-370-3p, oar-miR-411b-5p, oar-miR-379-3p and oar-miR-411a-3p) that had the most differential fold change were confirmed by RT-qPCR in ovine endometrium. The differentially expressed miRNAs targeted a total of 315 genes, resulting in 39 GO terms in molecular function, 353 in biological process, and 17 in the cellular component. The construction of the PPI network of target genes established two functional modules mostly enriched in the innate immune system, toll receptor cascades in module 1, whereas genes in module 2 were associated with GMCSF-mediated signaling events, insulin pathway, and mTOR signaling pathway. Based on the results, we may imply that miRNAs modulate ovine endometrium during the peri-implantation.

Expression pattern and cellular localization of two critical non-nuclear progesterone receptors in the ovine corpus luteum during the estrous cycle and early pregnancy.

The study aimed to investigate the expression and cellular localization of two critical non-nuclear progesterone receptors, including membrane-associated-progesterone-receptor-component-1 (PGRMC1) and progestin and adipoQ receptor family member 7 (PAQR7) throughout the estrous cycle and early pregnancy in ovine corpus luteum (CL). Ewes were randomly grouped into cyclic (C, n = 4 per group) or pregnant (P, n = 4 per group) groups. Following slaughtering, the CL was obtained from both cyclic and pregnant ewes on days 12 (C12 and P12), 16 (C16 and P16), and 22 (C22 and P22). Western blotting and RT-qPCR were utilized to assess the expression levels of PGRMC1 and PAQR7, whereas immunohistochemistry was performed to determine the localization of PGRMC1 and PAQR7 in CL. Data were evaluated by one-way ANOVA, and the P < 0.05 was considered a significant difference. PGRMC1 was shown to be expressed in both small and large luteal cells and endothelial cells in CL, while PAQR7 expression was only found in small and large luteal cells. Compared to cycle days, pregnancy increased the expression of PGRMC1. PAQR7 did not differ during early pregnancy but reduced during the functional luteolysis stage (C16). mRNA and protein expression patterns for PGRMC1 and PAQR7 were similar on the studied days. This is the first study that demonstrates the expression and cellular localization of PGRMC1 and PAQR7 in ovine CL. We suggest that these receptors could execute a significant role in the ovine CL life span in both cyclic changes and the establishment of pregnancy.

Relative abundance and localization of interferon-stimulated gene 15 mRNA transcript in intra- and extra-uterine tissues during the early stages of pregnancy in sheep.

The aim of this study was to investigate relative abundance and localization of ISG15 mRNA transcript in intra-uterine (trophoblast, endometrium) and extra-uterine (hypothalamus, anterior pituitary, corpus luteum) tissues before and during the period of conceptus implantation. Multiparous ewes (n = 16) were randomly allotted into four groups: pregnant or estrous cyclic on days of 12 and 16 (n = 4 per group) following estrus. Relative abundances of ISG15 mRNA transcript were determined in the endometrium, corpus luteum, hypothalamus, and anterior-pituitary using real time quantitative PCR. Localization of ISG15 mRNA transcript was evaluated using in situ hybridization. The presence of ISG15 mRNA transcript was only visualized in intra-uterine tissues including the endometrium and trophoblast on day 12 of pregnancy. The ISG15 mRNA transcript was detected in all tissues evaluated on day 16 of pregnancy. The abundance of ISG15 mRNA transcript was greater in the endometrium on day 12 of pregnancy than at other days when evaluations occurred while in all other tissues except the hypothalamus there were large abundances of ISG15 mRNA on day 16 of pregnancy. It is concluded that the ISG15 mRNA transcript is only present in intra-uterine tissues before conceptus implantation. The ISG15 mRNA transcript, however, is present in extra-uterine tissues of ewes during implantation probably due to an increased amount of interferon-tau in blood circulation that is produced by the developing embryo. Results also indicate, for the first time, that pregnancy is associated with an intra-hypothalamus and anterior pituitary increased abundance of ISG15 mRNA transcript in ewes.