Inhibition of miR-152 during In Vitro Maturation Enhances the Developmental Potential of Porcine Embryos

Abstract

Oocyte developmental competence is regulated by various mechanisms and molecules including microRNAs (miRNAs). However, the functions of many of these miRNAs in oocyte and embryo development are still unclear. In this study, we managed to manipulate the expression level of miR-152 during oocyte maturation to figure out its potential role in determining the developmental competence of porcine oocytes. The inhibition (Inh) of miR-152 during oocyte maturation does not affect the MII and cleavage rates, however it significantly enhances the blastocyst rate compared to the overexpression (OvExp) and control groups. Pathway analysis identified several signaling pathways (including PI3K/AKT, TGFβ, Hippo, FoxO, and Wnt signaling) that are enriched in the predicted target genes of miR-152. Gene expression analysis revealed that IGF1 was significantly up-regulated in the Inh group and downregulated in the OvExp group of oocytes. Moreover, IGF1R was significantly upregulated in the Inh oocyte group compared to the control one and IGFBP6 was downregulated in the Inh oocyte group compared to the other groups. Blastocysts developed from the OvExp oocytes exhibited an increase in miR-152 expression, dysregulation in some quality-related genes, and the lowest rate of blastocyst formation. In conclusion, our results demonstrate a negative correlation between miR-152 expression level and blastocyst rate in pigs. This correlation could be through targeting IGF system components during oocyte development.

Physiologically relevant miRNAs in mammalian oocytes are rare and highly abundant

“…Several studies reported the presence of functional miRNAs in murine, bovine, or porcine oocytes (Chen et al , 2012; Sinha et al , 2017; Wang et al , 2017; Gad et al , 2020). In these studies, experimental support for significant endogenous miRNA activity in oocytes was inferred from correlative effects of miRNA overexpression or use of antisense inhibitory oligonucleotides (“antagomirs”) (Krutzfeldt et al , 2005).…”