College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.
Key Laboratory of Crop and Animal Integrated Farming, Ministry of Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.
Funct Integr Genomics. 2022 Feb;22(1):77-87. doi: 10.1007/s10142-021-00814-8. Epub 2021 Nov 27.
In summer, heat stress is one of the primary reasons for the compromised health and low milk productivity of dairy cows. Hyperthermia affects milk synthesis and secretion in the mammary glands of dairy cows. As molecules for intercellular communication, milk-derived exosomes carry genetic material, proteins, and lipids, playing a crucial role in mammary tissue growth and milk synthesis in dairy cows. The aim of this study was to explore the milk exosomal miRNA profile of heat-stressed and normal Holstein cows. We isolated and identified milk exosomes to screening for differentially expressed miRNAs using small RNA sequencing. Then, TargetScan and miRanda algorithms were used to predict the putative targets of the differentially expressed miRNAs, whereas GO and KEGG pathway enrichment analyses were performed for the differentially expressed miRNA-target genes. Our results showed that 215 miRNAs were significantly differentially expressed in heat-stressed milk exosomes, of which one was upregulated and 214 were significantly downregulated. GO and KEGG enrichment analyses indicated that differentially expressed miRNAs might play a role in apoptosis, autophagy, and the p38 MAPK pathway. qRT-PCR assay verified that the expression of miRNAs was consistent with the sequencing results, warranting further verification of their specific targets of action. In conclusion, changes in the miRNA expression profile of milk exosomes indicated the role of exosomal miRNAs in regulating heat stress resistance and apoptosis in dairy cows. Our results suggested that milk-derived exosomal miRNAs could increase mammary gland resistance to heat stress, thereby enhancing milk synthesis in dairy cows.
在夏季，热应激是导致奶牛健康状况下降和产奶量降低的主要原因之一。体温过高会影响奶牛乳腺中乳汁的合成和分泌。作为细胞间通讯的分子，乳源性外泌体携带遗传物质、蛋白质和脂质，在奶牛乳腺组织生长和乳汁合成中发挥着重要作用。本研究旨在探讨热应激和正常荷斯坦奶牛乳中外泌体 miRNA 的特征。我们通过小 RNA 测序对分离和鉴定的乳外泌体进行差异表达 miRNA 的筛选。然后，使用 TargetScan 和 miRanda 算法预测差异表达 miRNA 的假定靶基因，对差异表达 miRNA-靶基因进行 GO 和 KEGG 通路富集分析。研究结果表明，热应激乳外泌体中 215 个 miRNA 表达显著差异，其中 1 个上调，214 个下调。GO 和 KEGG 富集分析表明，差异表达的 miRNA 可能在细胞凋亡、自噬和 p38 MAPK 通路中发挥作用。qRT-PCR 检测验证了 miRNA 的表达与测序结果一致，需要进一步验证其特定的作用靶点。总之，乳外泌体 miRNA 表达谱的变化表明外泌体 miRNA 在调节奶牛耐热性和细胞凋亡中起作用。研究结果表明，乳源性外泌体 miRNA 可以提高奶牛乳腺对热应激的抵抗力，从而提高奶牛的产奶量。
