Key Laboratory of Ruminant Molecular and Cellular Breeding of Ningxia Hui Autonomous Region, College of Animal Science and Technology, Ningxia University, Yinchuan, 750021, China.
BMC Genomics. 2024 Sep 19;25(1):882. doi: 10.1186/s12864-024-10761-w.
MicroRNA (miRNA) is a type of endogenous non-coding small RNA, which is abundant in living organisms. miRNAs play an important role in regulating gene expression and myriad cellular processes by binding to target messenger RNAs through complementary base pairing, and cross-species regulation mammalian cells by plant-derived xeno-miRNAs has been described. Here, we examined the miRNA species in two alfalfa (Medicago sativa, lucerne) cultivars commonly grown in Ningxia, China: cv. Zhongmu 1 and cv. Xinyan 52. Both cultivars have good salt and drought resistance. We found that the miRNA profiles were similar between the cultivars, with a slightly higher number of miRNAs present in the newer cv. Xinyan 52, which may contribute to its improved salt and drought tolerance. miRNAs were stable during drying, and some miRNAs were increased in dry versus fresh alfalfa, suggesting some miRNAs may be upregulated during drying. Alfalfa-derived miRNAs could be detected in exosomes from serum and whey collected from dairy cows, confirming the ability of the exogenous miRNAs (xeno-miRNAs) to enter the circulation and reach the mammary epithelium. In vitro studies confirmed that overexpression of mtr-miR156a could downregulate expression of Phosphatase 2 Regulatory Subunit B'gamma ( PPP2R5D) and Phosphoinositide-3-kinase Regulatory Subunit 2 (PIK3R2). Overexpression of mtr-miR156a also modulated PI3K-AKT-mTOR signaling as well as the casein content of milk produced by bovine mammary epithelial cells. Based on the known roles of PPP2R5D and PIK3R2 in regulating the PI3K-AKT-mTOR pathway as well as the effect of PI3K-AKT-mTOR on milk protein content, our findings implicate alfalfa-derived miR156a as a new cross-species regulator of milk quality in dairy cows.
微小 RNA（miRNA）是一种内源性非编码小 RNA，在生物体内广泛存在。miRNA 通过与靶信使 RNA 互补碱基配对结合，在调节基因表达和众多细胞过程中发挥重要作用，并且已经描述了植物源性外泌体 miRNA 对哺乳动物细胞的跨物种调节作用。在这里，我们研究了在中国宁夏广泛种植的两个紫花苜蓿（Medicago sativa，紫花苜蓿）品种：中苜 1 号和新研 52 号。这两个品种都具有良好的耐盐性和耐旱性。我们发现，这两个品种的 miRNA 谱相似，而更新的新研 52 号品种中存在的 miRNA 略多，这可能有助于提高其耐盐性和耐旱性。miRNA 在干燥过程中稳定，一些 miRNA 在干燥的紫花苜蓿中相对于新鲜的紫花苜蓿增加，这表明一些 miRNA 可能在干燥过程中被上调。从血清和乳清中分离出的奶牛 exosomes 中可以检测到源自紫花苜蓿的 miRNA，证实了外源性 miRNA（外泌体 miRNA）进入循环并到达乳腺上皮的能力。体外研究证实，mtr-miR156a 的过表达可以下调磷酸酶 2 调节亚基 B'gamma（PPP2R5D）和磷脂酰肌醇 3-激酶调节亚基 2（PIK3R2）的表达。mtr-miR156a 的过表达还调节了 PI3K-AKT-mTOR 信号通路以及牛乳腺上皮细胞产生的牛奶中酪蛋白的含量。基于 PPP2R5D 和 PIK3R2 在调节 PI3K-AKT-mTOR 通路中的已知作用以及 PI3K-AKT-mTOR 对乳蛋白含量的影响，我们的研究结果表明，源自紫花苜蓿的 miR156a 是奶牛乳质量的一种新的跨物种调节因子。
