Yue Wang1, Hui-Li Wang1,2, Zhi-Ping Lin2, Ji-Feng Zhong1,2, Kun-Lin Chen3,4, Xing Duan5. 1. Institute of Animal Science/Key Laboratory for Crop and Animal Integrated Farming of Ministry of Agriculture and Rural Affairs, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China. 2. Youyuan Research Institute of Dairy Industry Co., Ltd, Nanjing, 211100, China. 3. Institute of Animal Science/Key Laboratory for Crop and Animal Integrated Farming of Ministry of Agriculture and Rural Affairs, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China. chenkunlin@jaas.ac.cn. 4. Youyuan Research Institute of Dairy Industry Co., Ltd, Nanjing, 211100, China. chenkunlin@jaas.ac.cn. 5. Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology, College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, 311300, China. duanxing@zafu.edu.cn.
Abstract
BACKGROUND: Exosomes are involved in intercellular communication, affecting many physiological and pathological process. The present study evaluated the effects of serum exosomes on the function of bovine mammary epithelial cells (BMECs) and milk synthesis under heat stress. METHODS AND RESULTS: We cultured the BMECs in fetal bovine serum (FBS) or exosome-free FBS medium and examined, their viability using CCK-8 kit. The results showed that culturing the cells in an exosome-free medium decreased viability and increased the levels of reactive oxygen species. The BMECs cultured in the exosome-free medium had reduced mitochondrial membrane potential, decreased manganese superoxide dismutase activity, and disrupted mitochondrial dynamics. They exhibited apoptosis due to upregulated Drp1, Fis1, Bax and HSP70. Lastly, we observed downregulation of milk fat and lactoprotein-related genes: mTOR, PPARγ, p-mTOR and ADD1 and SREBP1, ELF5, and CSN2, respectively, after culturing the cells in an exosome-free medium. These negative effects of the exosome-free medium on the BMECs could be further reinforced under heat stress. CONCLUSION: Our results demonstrated that exosomes from serum are critical for maintaining the normal function of BMECs.
BACKGROUND: Exosomes are involved in intercellular communication, affecting many physiological and pathological process. The present study evaluated the effects of serum exosomes on the function of bovine mammary epithelial cells (BMECs) and milk synthesis under heat stress. METHODS AND RESULTS: We cultured the BMECs in fetal bovine serum (FBS) or exosome-free FBS medium and examined, their viability using CCK-8 kit. The results showed that culturing the cells in an exosome-free medium decreased viability and increased the levels of reactive oxygen species. The BMECs cultured in the exosome-free medium had reduced mitochondrial membrane potential, decreased manganese superoxide dismutase activity, and disrupted mitochondrial dynamics. They exhibited apoptosis due to upregulated Drp1, Fis1, Bax and HSP70. Lastly, we observed downregulation of milk fat and lactoprotein-related genes: mTOR, PPARγ, p-mTOR and ADD1 and SREBP1, ELF5, and CSN2, respectively, after culturing the cells in an exosome-free medium. These negative effects of the exosome-free medium on the BMECs could be further reinforced under heat stress. CONCLUSION: Our results demonstrated that exosomes from serum are critical for maintaining the normal function of BMECs.