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Background <p>Exosomes are crucial mediators of intercellular communication. As a key component of milk, milk-derived exosomes are abundant in genetic cargo, particularly microRNAs (miRNAs), indicating their potential role in regulating mammary gland physiology. Therefore, this study aimed to investigate the specificity of miRNAs in milk-derived exosomes and their regulatory roles in lipid synthesis in bovine mammary epithelial cells (BMECs).</p> Results <p>Based on 17,838 DHI records showing a significantly higher milk fat percentage (MFP) in late lactation (4.24% ± 1.07%), 10 high- (5.96% ± 0.26%, HMF) and 10 low-MFP (1.68% ± 0.23%, LMF) cows were selected during this stage for milk-derived exosome isolation and miRNA profiling. Exosomes isolated via differential ultracentrifugation were verified as 50–150&#xa0;nm vesicles expressing CD9, CD81, and TSG101. miRNA sequencing identified 1,320 differentially expressed miRNAs (496 upregulated and 824 downregulated) between the HMF_EXO and LMF_EXO groups. Uptake assays confirmed that BMECs internalized these exosomes, and qRT-PCR validation showed that miR-423-5p and miR-125b were significantly upregulated and downregulated in HMF_EXO- and LMF_EXO-treated BMECs, respectively. Functionally, exosomal miR-423-5p promoted intracellular lipid accumulation and TG synthesis in BMECs by targeting <i>APOA5</i>, whereas miR-125b inhibited lipolysis and fatty acid oxidation by repressing <i>SLC27A1</i>.</p> Conclusions <p>This study demonstrates that milk-derived exosomal miRNAs represent a novel mechanism for regulating milk fat synthesis. Specifically, miR-423-5p and miR-125b directly modulated lipid metabolism in BMECs via the miR-423-5p/<i>APOA5</i> and miR-125b/<i>SLC27A1</i> pathways. These findings provide new insights into the molecular regulation of milk fat synthesis and highlight the importance of exosome-mediated intercellular communication in the lactating mammary gland.</p> Graphical Abstract <p></p>

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Functional analysis and identification of miRNAs associated with lipid metabolism from milk-derived exosomes

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年2月4日

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  • Xin Lu,
  • Tianyu Deng,
  • Yue Liu,
  • Xiaohan Zhang,
  • Xue Bai,
  • Xibi Fang,
  • Runjun Yang

摘要

Background

Exosomes are crucial mediators of intercellular communication. As a key component of milk, milk-derived exosomes are abundant in genetic cargo, particularly microRNAs (miRNAs), indicating their potential role in regulating mammary gland physiology. Therefore, this study aimed to investigate the specificity of miRNAs in milk-derived exosomes and their regulatory roles in lipid synthesis in bovine mammary epithelial cells (BMECs).

Results

Based on 17,838 DHI records showing a significantly higher milk fat percentage (MFP) in late lactation (4.24% ± 1.07%), 10 high- (5.96% ± 0.26%, HMF) and 10 low-MFP (1.68% ± 0.23%, LMF) cows were selected during this stage for milk-derived exosome isolation and miRNA profiling. Exosomes isolated via differential ultracentrifugation were verified as 50–150 nm vesicles expressing CD9, CD81, and TSG101. miRNA sequencing identified 1,320 differentially expressed miRNAs (496 upregulated and 824 downregulated) between the HMF_EXO and LMF_EXO groups. Uptake assays confirmed that BMECs internalized these exosomes, and qRT-PCR validation showed that miR-423-5p and miR-125b were significantly upregulated and downregulated in HMF_EXO- and LMF_EXO-treated BMECs, respectively. Functionally, exosomal miR-423-5p promoted intracellular lipid accumulation and TG synthesis in BMECs by targeting APOA5, whereas miR-125b inhibited lipolysis and fatty acid oxidation by repressing SLC27A1.

Conclusions

This study demonstrates that milk-derived exosomal miRNAs represent a novel mechanism for regulating milk fat synthesis. Specifically, miR-423-5p and miR-125b directly modulated lipid metabolism in BMECs via the miR-423-5p/APOA5 and miR-125b/SLC27A1 pathways. These findings provide new insights into the molecular regulation of milk fat synthesis and highlight the importance of exosome-mediated intercellular communication in the lactating mammary gland.

Graphical Abstract