精氨酸通过GPRC6 A/Akt-mTOR信号通路刺激奶牛乳腺上皮细胞增殖和乳脂脂肪酸合成OA

This study aimed to investigate the effects of arginine(Arg)on proliferation and milk fat fatty acid synthesis of bovine mammary epithelial cells(BMECs)through G protein-coupled receptor family C,group 6 and subtype A(GPRC6A)/protein kinase B(Akt)-mammalian target of rapamycin(mTOR)signaling path-way,and systematically evaluate its regulatory effects and molecular mechanisms on the proliferation activity,apoptosis level and milk fat synthesis ability of BMECs.Using BMECs as a model,the cell proliferation was assessed by CCK-8,and the expression of proteins related to proliferation,apoptosis and fatty acid synthesis was detected by Western blot.The cells were treated with the Akt inhibitor(AKT-IN-1),mTOR inhibitor(ra-pamycin),AMP-activated protein kinase(AMPK)activator(EX229)and GPRC6A mall interfering RNA(siRNA),to verify the signaling pathway dependency of Arg's effects.The results showed that 1.00 μmol/L Arg significantly promoted BMECs proliferation(P＜0.05),significant or extremely significant up-regulated the protein expression levels of proliferation marker proteins such as proliferating cell nuclear antigen(PC-NA),cyclin D1(Cyclin D1)and B-cell lymphoma 2(BCL2)(P＜0.05 or P＜0.01),and significant or ex-tremely significant down-regulated the protein expression levels of pro-apoptotic proteins such as BCL2 associ-ated X protein(BAX),cysteine aspartic acid specific protease-3(Caspase-3)and cysteine aspartic acid spe-cific protease-9(Caspase-9)(P＜0.05 or P＜0.01).Arg activated GPRC6A and its downstream Akt-mTOR signaling pathway,and the proliferative and anti-apoptotic effects were reversed by GPRC6A siRNA or Akt/mTOR inhibitors.In addition,1.00 μmol/L Arg significant or extremely significant up-regulated the protein expression levels of fatty acid synthesis-related proteins such as peroxisome proliferator-activated receptor gam-ma(PPARγ),sterol regulatory element-binding protein 1(SREBP1),fatty acid synthase(FASN)and stearoyl-CoA desaturase 1(SCD1)(P＜0.05 or P＜0.01),and the AMPK activation or GPRC6A siRNA could blocked the fatty acid synthesis-promoting effect of Arg.Collectively,the Arg promotes BMECs prolifer-ation and inhibits apoptosis via the GPRC6A receptor mediated activation of the Akt-mTOR signaling pathway,and enhances the milk fat fatty acid synthesis through the GPRC6A/AMPK axis,providing a theoretical basis for targeted regulation of milk component synthesis.[Chinese Journal of Animal Nutrition,2026,38(3):2173-2183]