Background Exosomes are crucial mediators of intercellular communication.As a key component of milk,milkderived exosomes are abundant in genetic cargo,particularly micro RNAs(mi RNAs),indicating their potential role i...Background Exosomes are crucial mediators of intercellular communication.As a key component of milk,milkderived exosomes are abundant in genetic cargo,particularly micro RNAs(mi RNAs),indicating their potential role in regulating mammary gland physiology.Therefore,this study aimed to investigate the specificity of mi RNAs in milkderived 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 mi RNA profiling.Exosomes isolated via differential ultracentrifugation were verified as 50-150 nm vesicles expressing CD9,CD81,and TSG101.mi RNA sequencing identified 1,320 differentially expressed mi RNAs(496 upregulated and 824 downregulated)between the HMF_EXO and LMF_EXO groups.Uptake assays confirmed that BMECs internalized these exosomes,and q RT-PCR validation showed that mi R-423-5p and mi R-125b were significantly upregulated and downregulated in HMF_EXO-and LMF_EXO-treated BMECs,respectively.Functionally,exosomal mi R-423-5p promoted intracellular lipid accumulation and TG synthesis in BMECs by targeting APOA5,whereas mi R-125b inhibited lipolysis and fatty acid oxidation by repressing SLC27A1.Conclusions This study demonstrates that milk-derived exosomal mi RNAs represent a novel mechanism for regulating milk fat synthesis.Specifically,mi R-423-5p and mi R-125b directly modulated lipid metabolism in BMECs via the mi R-423-5p/APOA5 and mi R-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.展开更多
基金supported by the National Natural Science Foundation of China(no.32372838,U22A20506)the National Key Research and Development Program of China(no.2024YFD1300104)+1 种基金the scientific and technological development program of Jilin province(YDZJ202203CGZH037)the earmarked fund for JLARS-2025-070203。
文摘Background Exosomes are crucial mediators of intercellular communication.As a key component of milk,milkderived exosomes are abundant in genetic cargo,particularly micro RNAs(mi RNAs),indicating their potential role in regulating mammary gland physiology.Therefore,this study aimed to investigate the specificity of mi RNAs in milkderived 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 mi RNA profiling.Exosomes isolated via differential ultracentrifugation were verified as 50-150 nm vesicles expressing CD9,CD81,and TSG101.mi RNA sequencing identified 1,320 differentially expressed mi RNAs(496 upregulated and 824 downregulated)between the HMF_EXO and LMF_EXO groups.Uptake assays confirmed that BMECs internalized these exosomes,and q RT-PCR validation showed that mi R-423-5p and mi R-125b were significantly upregulated and downregulated in HMF_EXO-and LMF_EXO-treated BMECs,respectively.Functionally,exosomal mi R-423-5p promoted intracellular lipid accumulation and TG synthesis in BMECs by targeting APOA5,whereas mi R-125b inhibited lipolysis and fatty acid oxidation by repressing SLC27A1.Conclusions This study demonstrates that milk-derived exosomal mi RNAs represent a novel mechanism for regulating milk fat synthesis.Specifically,mi R-423-5p and mi R-125b directly modulated lipid metabolism in BMECs via the mi R-423-5p/APOA5 and mi R-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.
