MicroRNAs (miRNAs) are small, non-coding RNAs which are produced throughout the body. Individual tissues tend to have a specific expression profile and excrete many of these miRNAs into circulation. These circulating miRNAs may be diagnostically valuable biomarkers for assessing the presence of disease while minimizing invasive testing. In women, numerous circulating miRNAs have been identified which change significantly during pregnancy-related complications (e.g. chorioamnionitis, eclampsia, recurrent pregnancy loss); however, no prior work has been done in this area in the horse. To identify pregnancy-specific miRNAs, we collected serial whole blood samples in pregnant mares at 8, 9, 10 m of gestation and post-partum, as well as from non-pregnant (diestrous) mares. In total, we evaluated a panel of 178 miRNAs using qPCR, eventually identifying five miRNAs of interest. One miRNA (miR-374b) was differentially regulated through late gestation and four miRNAs (miR-454, miR-133b, miR-486-5p and miR-204b) were differentially regulated between the pregnant and non-pregnant samples. We were able to identify putative targets for the differentially regulated miRNAs using two separate target prediction programs, miRDB and Ingenuity Pathway Analysis. The targets for the miRNAs differentially regulated during pregnancy were predicted to be involved in signaling pathways such as the STAT3 pathway and PI3/AKT signaling pathway, as well as more endocrine-based pathways, including the GnRH, prolactin and insulin signaling pathways. In summary, this study provides novel information about the changes occurring in circulating miRNAs during normal pregnancy, as well as attempting to predict the biological effects induced by these miRNAs.

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Notes/Citation Information

Published in PLOS ONE, v. 12, 4, e0175045, p. 1-12.

© 2017 Loux et al.

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Funding Information

This work was funded by the Kentucky Thoroughbred Association/Kentucky Thoroughbred Breeders and Owners (http://www.kentuckybred.org), the Albert Clay Endowment and the Paul Mellon post-doctoral fellowship, and the Geoffrey Hughes doctoral fellowship. Due to their relatively small size, not all funding sources have a website or grant numbers.

journal.pone.0175045.s001.xlsx (324 kB)
S1 File. Raw and normalized Ct values for qPCR.

journal.pone.0175045.s002.xlsx (83 kB)
S2 File. Putative mRNA targets.

journal.pone.0175045.s003.xls (94 kB)
S3 File. Predicted canonical pathways.

journal.pone.0175045.s004.docx (17 kB)
S1 Table. Primer sequences.