Abstract MicroRNAs (miRNAs) are short noncoding RNAs that can regulate target gene expression at the posttranscriptional level. It has been reported that bta-miR-145 shows differential expression between the different lactation stages of bovine mammary glands, but the function of bta-miR-145 in normal mammary glands remains unknown. The overexpression of bta-miR-145 significantly decreased the proliferation of mammary epithelial cells (p < .05), and this effect was reversed upon bta-miR-145 inhibition. Using several miRNA prediction programmes, insulin receptor substrate 1 (IRS1) was predicted to be a potential target of miR-145. Using the DAVID database, many predicted targets of bta-miR-145 were found to be involved in the MAPK signalling pathway associated with cell proliferation, including IRS1. Bovine IRS1 3’RACE sequencing and reference comparison revealed that possible binding sites for bta-miR-145 still exist in IRS1. The IRS1 mRNA level was not affected by the transfection of primary bovine mammary epithelial cells with 150 pmol of a bta-miR-145 mimic or 300 pmol of a bta-miR-145 inhibitor for 24 h (pBMEC, p > .05), whereas the IRS1 protein level was changed significantly after bta-miR-145 mimic or inhibitor transfection for 72 h (p < .05). Taken together, these results suggest that bta-miR-145 is involved in the proliferation of bovine mammary epithelial cells by targeting IRS1, which is related to the MAPK signalling pathway. Highlights Bta-miR-145 affects bovine mammary epithelial cell vitality in primary bovine mammary epithelial cells. IRS1 was verified as target gene of bta-miR-145. IRS1 belongs to MAPK signaling pathway, which regulate cell proliferation.

中文翻译：

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MiR-145参与牛乳腺上皮细胞增殖并调节牛胰岛素受体底物1

摘要 MicroRNAs (miRNAs)是短的非编码RNAs，可以在转录后水平调控靶基因的表达。据报道，bta-miR-145 在牛乳腺的不同泌乳阶段之间表现出差异表达，但 bta-miR-145 在正常乳腺中的功能仍然未知。bta-miR-145 的过表达显着降低了乳腺上皮细胞的增殖（p < .05），并且这种效果在 bta-miR-145 抑制后被逆转。使用几个 miRNA 预测程序，胰岛素受体底物 1 (IRS1) 被预测为 miR-145 的潜在目标。使用 DAVID 数据库，发现 bta-miR-145 的许多预测目标参与与细胞增殖相关的 MAPK 信号通路，包括 IRS1。牛 IRS1 3'RACE 测序和参考比较显示 IRS1 中仍然存在 bta-miR-145 的可能结合位点。IRS1 mRNA 水平不受用 150 pmol bta-miR-145 模拟物或 300 pmol bta-miR-145 抑制剂转染原代牛乳腺上皮细胞 24 小时的影响（pBMEC，p > .05），而在 bta-miR-145 模拟物或抑制剂转染 72 小时后，IRS1 蛋白水平发生显着变化（p < .05）。综上所述，这些结果表明 bta-miR-145 通过靶向与 MAPK 信号通路相关的 IRS1 参与牛乳腺上皮细胞的增殖。亮点 Bta-miR-145 影响原代牛乳腺上皮细胞中的牛乳腺上皮细胞活力。IRS1 被证实为 bta-miR-145 的靶基因。IRS1 属于 MAPK 信号通路，