繁殖・生殖工学

[IV-20-13] Relationship between miRNA expression in intrauterine exosomes and fertility in cows

*Rei Ichikawa¹, Seiya Higashi¹, Sho Nakamura¹, Satoshi Ohkura¹, Koji Kimura², Shuichi Matsuyama¹ (1. Graduate School of Bioagricultural Sciences, Nagoya Univ. , 2. Laboratory of Reproductive Physiology, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan)

MicroRNAs (miRNAs) in intrauterine exosomes play roles in conceptus–maternal interactions before implantation. We hypothesized that miRNAs in the intrauterine exosomes of low-fertile cows would impair embryonic development and survival before implantation, resulting in infertility. In this study, the exosome intake by embryo was confirmed. Then, a small RNA-sequencing analysis was conducted using miRNAs from the intrauterine exosomes of normal and low-fertile cows 7 days after estrus. The expression levels of 8 miRNAs in low-fertile cows were significantly higher than in normal-fertile cows, of which miR-1 exhibited the highest expression levels (P = 0.08). To determine the timing of miRNA introduction into embryos by lipofection the fluorescent-labeled oligonucleotide was introduced into the blastocysts at each stage. The fluorescence was observed only in the hatched blastocyst. In summary, this study revealed that miR-1 in bovine intrauterine exosomes is associated with low fertility and established a lipofection method to transfer miRNA into embryos. Future studies will examine the effects of miR-1 on embryonic development and survival.