To investigate the role of glucose in regulating milk fatty acid synthesis,6 lactating Guanzhong dairy goats were infused with 0,60,or 100 g/d glucose via the external pubic artery in a 3×3 repeated Latin square experiment.A concomitant in vitro experiment was conducted to investigate possible mecha-nisms whereby glucose regulates milk fatty acid synthesis.RNA sequencing was used for cellular tran-scriptome analysis.Drugs,MK-2206,rapamycin,and dorsomorphin were used to block cellular mammalian AMP-activated protein kinase(AMPK),AKT serine/threonine kinase 1,and mechanistic target of rapamycin kinase signaling pathways,respectively.Carbohydrate response element binding protein(ChREBP)was knockdown and overexpressed to investigate its role in regulating milk fatty acid synthesis in mammary epithelial cells.Glucose infusion linearly elevated the concentration of C8:0(P=0.039)and C10:0(P=0.041)in milk fat while it linearly decreased(P=0.049)that of C16:0.This result was in agreement with the upregulation of genes related to de novo synthesis of fatty acids and lipid droplet formation,including adipose differentiation-related protein,butyrophilin subfamily 1 member A1,fatty acid synthase(FASN)and ChREBP.Their expression increased(P＜0.05)linearly in the lactating goat mammary gland.In vitro,glucose linearly stimulated the expression of genes related to de novo synthesis of fatty acids and cellular triacylglycerol in cultured mammary epithelial cells.RNA sequencing and inhibition studies revealed that glucose induced transcriptomic changes increasing lipogenic pathways,with AMPK responding to glucose by controlling ChREBP and FASN.Knockdown and overexpression of ChREBP highlighted its essential role in lipogenesis.The knockdown and over-expression of ChREBP protein also revealed an essential role in regulating the de novo synthesis of fatty acids.Collectively,our data highlight that glucose supplementation promotes de novo fatty acid syn-thesis via the AMPK-ChREBP axis,hence increasing milk fat yield in the goat mammary gland.Results from the current study provide possible strategies to manipulate the fatty acid composition as well as improve ruminant milk quality.

Hengbo Shi;Nannan Jiang;Ling Wei;Jie Cai;Wenying Zhang;Qianming Jiang;Juan J.Loor;Jianxin Liu

Institute of Dairy Science,College of Animal Sciences,Zhejiang University,Hangzhou,310058,China;College of Life Sciences and Medicine,Zhejiang Sci-Tech University,Hangzhou,310018,China;Mammalian Nutrition Physiology Genomics,Department of Animal Sciences and Division of Nutritional Sciences,University of Illinois,Urbana,IL,61801,USA

动物营养（英文）

[1]Hengbo Shi;Nannan Jiang;Ling Wei;Jie Cai;Wenying Zhang;Qianming Jiang;Juan J.Loor;Jianxin Liu-.AMPK-ChREBP axis mediates de novo milk fatty acid synthesis promoted by glucose in the mammary gland of lactating goats)[J].动物营养（英文）,2022(03):234-242

butyrophilin

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