GSK3β調節奶牛乳腺上皮細胞乳蛋白和乳脂肪合成

張霞 趙鋒 黃玉玲 李慶章 高學軍

摘 要：GSK3β為AKT1下游信號分子，受PI3K/AKT調控。GSK3β磷酸化后被抑制，通過調節下游分子elF2B等促進乳蛋白合成。mTOR在調節乳蛋白合成中發揮重要作用，近來發現GSK3β和mTORC1均可通過調節SREBP1促進乳脂合成。但尚不清楚GSK3β和mTORC1在調節乳蛋白和乳脂合成方面的相互作用關系。該研究通過對GSK3β進行超表達和抑制，觀察其對體外培養的奶牛乳腺上皮細胞細胞增殖、乳蛋白和乳脂肪合成的影響，及對mTOR途徑的影響。結果發現GSK3β是奶牛乳腺上皮細胞細胞增殖、乳蛋白和乳脂肪合成的負調控分子，通過抑制mTORC1發揮作用。蛋氨酸可以抑制GSK3β和激活mTORC1，促進細胞增殖、乳蛋白和乳脂肪合成。該研究結果進一步揭示了GSK3β在奶牛乳腺上皮細胞細胞增殖、乳蛋白和乳脂肪合成中的負調控分子機理。

關鍵詞：糖原合成酶激酶3β 奶牛乳腺上皮細胞 mTOR SREBP1 乳蛋白 乳脂肪

GSK3β Regulates Milk Protein and Fat Synthesis in Dairy Cow Mammary Epithelial Cells in Vitro

Zhang Xia Zhao Feng Huang Yuling Li Qingzhang Gao Xuejun

（Northeast Agricultural University）

Abstract：GSK3β acting as the downstream of AKT1， its activity is regulated by activation of the PI3K/AKT survival pathway and inhibitory phosphorylation of GSK3β can regulate in turn through phosphorylation of several proteins （such as elF2B） to promote protein synthesis. In addition， mTOR pathway also can regulate protein synthesis and recent studies have found that both GSK3β and mTORC1 can regulate SREBP1 to promote fat synthesis. However， so far， the cross talk between GSK3β and the mTOR pathway in dairy cow mammary epithelial cells （DCMECs） to regulate milk protein and fat synthesis is not well known. In this study we constructed transfected DCMECs with GSK3β and its inhibitor in order to analyze the expression and localization of GSK3β and the function in transfected DCMECs by CASY， fluorescent immunostaining， western blotting. Overexpression and inhibition experiments showed that the inactivity of GSK3β promoted proliferation and upregulated milk protein and fat synthesis through mTOR pathway in DCMECs. Furthermore， methionine （Met） could enhance this action， Met and Licl （Lithium Chloride， a GSK3β inhibitor） can coordinate together to promote protein synthesis. These ？ndings that GSK3β involves in regulation of milk synthesis shed new insights for understanding the mechanisms of milk protein and fat synthesis.

Key Words：Glycogen synthase kinase 3β； Dairy cow mammary epithelial cells； mTOR； SREBP1； Milk protein； Milk fat

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