(P-351) Differential expression of microRNAs predicted against connexins 37 and 43 mRNA between oocytes and cumulus cells in canines.

Abstract Authors: Monica I De los Reyes¹, Jaime A Palomino², Phillip Dettleff^{3
1 Laboratory of Animal Reproduction, Faculty of Veterinary Sciences, University of Chile.
2 School of veterinary Medicine, Faculty of medical Sciences, Berardo O'Higgins University
3 School of Veterinary Medicine, Faculty of Agronomy and Natural Sciences. Pontifical Catholic University of Chile}

Abstract Text: Connexins 37 (Cx37) and 43 (Cx4) participate in the bi-directional communication between the oocyte and its companion cumulus cells (CCs). Several post-translational factors, including miRNA, control connexins; therefore, the aim of this study was to determine the expression levels of miRNAs predicted against canine Cx37 and Cx43 mRNA in CCs and oocytes. Cumulus oocyte complexes were retrieved from small (∼0.25–0.39 mm) and medium (∼0.4–3.9 mm) antral follicles from more than 100 dog ovaries following ovariohysterectomies. CCs were mechanically removed from the oocytes. Specific miRNAs regulating Cx37 and Cx43 genes were selected from miRNA databases. The best miRNA for each target gene (Cx37 and Cx43) was selected considering qPCR performance (low ct value and specific melt curve) and target prediction probability with a binding p-value of 1.0, choosing for the study cfa-miR-1838 against Cx37 mRNA and cfa-miR-130b against Cx43 mRNA. The expression level of each miRNA in the oocytes and CCs from both follicle sizes was evaluated using ANOVA. The relative abundance of cfa-miR-1838 was the highest (P< 0.05) in oocytes from the small follicles, whereas the lowest (P< 0.05) value was observed in CCs from medium antral follicles. Cfa-miR-130b abundance was higher (P< 0.05) in oocytes compared to CCs in both follicle sizes. Therefore, the expression of cfa-miR-1838 and cfa-miR-130b differed (P< 0.05) between the oocytes and CCs from small and medium antral follicles. These miRNAs against canine Cx37 and Cx43 mRNA could play a role in regulating oocyte and CC cross-talk. Grant FONDCYT 1211285