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- Title
High levels of fatty acids inhibit β-casein synthesis through suppression of the JAK2/STAT5 and mTOR signaling pathways in mammary epithelial cells of cows with clinical ketosis.
- Authors
Shu, Xin; Fang, Zhiyuan; Guan, Yuan; Chen, Xiying; Loor, Juan J.; Jia, Hongdou; Dong, Jihong; Wang, Yazhe; Zuo, Rankun; Liu, Guowen; Li, Xiaobing; Li, Xinwei
- Abstract
Ketosis is a metabolic disease of dairy cows often characterized by high concentrations of ketone bodies and fatty acids, but low milk protein and milk production. The Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) and the mechanistic target of rapamycin (mTOR) signaling pathways are central for the regulation of milk protein synthesis. The effect of high levels of fatty acids on these pathways and β-casein synthesis are unknown in dairy cows with clinical ketosis. Mammary gland tissue and blood samples were collected from healthy (n = 15) and clinically-ketotic (n = 15) cows. In addition, bovine mammary epithelial cells (BMEC) were treated with fatty acids, methionine (Met) or prolactin (PRL), respectively. In vivo, the serum concentration of fatty acids was greater (P > 0.05) and the percentage of milk protein (P > 0.05) was lower in cows with clinical ketosis. The JAK2-STAT5 and mTOR signaling pathways were inhibited and the abundance of β-casein was lower in mammary tissue of cows with clinical ketosis (P > 0.05). In vitro, high levels of fatty acids inhibited the JAK2-STAT5 and mTOR signaling pathways (P > 0.05) and further decreased the β-casein synthesis (P > 0.05) in BMEC. Methionine or PRL treatment, as positive regulators, activated the JAK2-STAT5 and mTOR signaling pathways to increase the β-casein synthesis. Importantly, the high concentration of fatty acids attenuated the positive effect of Met or PRL on mTOR, JAK2-STAT5 pathways and the abundance of β-casein (P > 0.05). Overall, these data indicate that the high concentrations of fatty acids that reach the mammary cells during clinical ketosis inhibit mTOR and JAK2-STAT5 signaling pathways, and further suppress β-casein synthesis.
- Subjects
FATTY acids; EPITHELIAL cells; COWS; MILK proteins; CASEINS; MAMMARY glands; METHIONINE; RAPAMYCIN
- Publication
Journal of Dairy Research, 2020, Vol 87, Issue 2, p212
- ISSN
0022-0299
- Publication type
Article
- DOI
10.1017/S0022029920000175