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  • Author: Masatoshi Hori x
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Katsuhiko Yasuda, Tsuyoshi Nakamoto, Masahiro Yasuhara, Hidetaka Okada, Tatsuya Nakajima, Hideharu Kanzaki, Masatoshi Hori and Hiroshi Ozaki

To assess the role of protein kinase Cβ (PKCβ) in human myometrial contractions during pregnancy, we evaluated the effect of a PKCβ inhibitor (LY333531) on the pregnant and nonpregnant myometrial contractions and compared the level of PKCβ in the pregnant myometrium with that in the nonpregnant myometrium. The effects of LY333531 on the myometrial contractions were examined by measuring contractile activity (frequency and amplitude). PKCβ in human myometrium was assessed at mRNA level using real-time PCR method. The characteristics of contractile activity were different between the pregnant and the nonpregnant myometrium. The amplitude of rhythmic contractions in the preterm and term myometrium was increased 2- to 2.5-fold when compared with that in the nonpregnant myometrium, but the frequency of rhythmic contractions was decreased by about half. LY333531 (10−6 M) reduced the increased amplitude in the preterm and term myometrium by about 50%, and the inhibitory effects of LY333531 in the pregnant myometrium were significantly greater than that in the nonpregnant myometrium (about 50 vs 25%). However, the frequency in the pregnant and nonpregnant myometrium was not influenced by LY333531. Real-time PCR revealed a significant, five- to sevenfold increase in the expression of PKCβ mRNA in the preterm and term myometrium when compared with the nonpregnant myometrium. These findings suggest that the increased amplitude of human myometrial contractions during pregnancy is related to the increased level of PKCβ. A PKCβ inhibitor may reduce preterm uterine contractions and prevent preterm delivery.

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Keigo Nakamura, Kazuya Kusama, Atsushi Ideta, Kazuhiko Imakawa and Masatoshi Hori

Extracellular vesicles (EVs) present in uterine lumen are involved in conceptus-endometrial interactions during the pre-implantation period. Despite numerous studies conducted on interferon tau (IFNT), a major protein of maternal recognition of pregnancy, the effect of intrauterine EVs on the endometrium during pre-implantation periods has not been well-characterized. To characterize conceptus-derived intrauterine EVs independent of IFNT, transcripts found from RNA-seq analysis in RNAs extracted from primary bovine endometrial epithelial cells (EECs) treated with cyclic day 17 (C17) EVs, pregnant day 17 (P17) EVs or IFNT were analyzed. These analyses identified 82 transcripts uniquely induced by IFNT-independent P17 EVs, of which a large number of transcripts were associated with ‘the TNF signaling pathway’ and ‘Inflammatory response’. Moreover, high expression of CD40L, a member of the TNF superfamily, and its receptor CD40 were found in P17 EVs and in EECs, respectively. Furthermore, the expression of TNF signaling pathway-related genes was up-regulated by the treatment with P17 EVs, but these increases were down-regulated by NF-kB signaling inhibitor. These findings suggest that P17 EVs could induce a pro-inflammatory response in the endometrium, independent of IFNT, to regulate uterine receptivity, facilitating conceptus implantation.