The Key Laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Xiangfang District, Harbin, Heilongjiang Province, China.
In Vitro Cell Dev Biol Anim. 2012 Aug;48(7):449-57. doi: 10.1007/s11626-012-9531-y. Epub 2012 Jul 18.
Estrogen regulates a variety of physiological processes, including mammary gland growth, morphogenesis of the mammary gland, proliferation and differentiation, and elevating the expression of milk proteins. Many nuclear phosphorylated proteins such as pStat5 and mTOR regulate milk protein synthesis. But the detail of milk protein synthesis controlled at the transcript level and posttranslational level is not well-known. To contribute to the understanding of the molecular mechanism underlying estrogen action on the dairy cow mammary epithelial cells (DCMECs), nuclear phosphorylated proteins regulated by estrogen in DCMECs were identified. Two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization/time of flight mass spectrometry were used to identify the changes of nuclear phosphorylated proteins in DCMECs treated with estrogen. Seven proteins were identified differentially up-expressed in DCMECs after 24-h estrogen exposure: including glycyl-tRNA synthetase, previously reported in milk protein synthesis of DCMECs, belonging to the class-II aminoacyl-tRNA synthetase family; proteins involved in other cellular functions, such as translation initiation factors, GTP-binding nuclear proteins, heat-shock proteins, and proteins belonging to ubiquitin-proteasome system. This screening reveals that estrogen influences the levels of nuclear phosphorylated proteins of DCMECs which opens new avenue for the study of the molecular mechanism linking to milk synthesis.
雌激素调节多种生理过程，包括乳腺生长、乳腺形态发生、增殖和分化，并提高乳蛋白的表达。许多核磷酸化蛋白，如 pStat5 和 mTOR，调节乳蛋白合成。但是，转录水平和翻译后水平控制乳蛋白合成的细节尚不清楚。为了深入了解雌激素对奶牛乳腺上皮细胞（DCMECs）作用的分子机制，鉴定了雌激素调节的 DCMECs 中的核磷酸化蛋白。使用二维凝胶电泳和基质辅助激光解吸/电离/飞行时间质谱鉴定了雌激素处理的 DCMECs 中核磷酸化蛋白的变化。在雌激素暴露 24 小时后，DCMECs 中鉴定出 7 种差异表达的核磷酸化蛋白：包括甘氨酰-tRNA 合成酶，先前报道在 DCMECs 的乳蛋白合成中，属于 II 类氨酰-tRNA 合成酶家族；参与其他细胞功能的蛋白质，如翻译起始因子、GTP 结合核蛋白、热休克蛋白和属于泛素-蛋白酶体系统的蛋白质。这种筛选揭示了雌激素影响 DCMECs 核磷酸化蛋白的水平，为研究与乳合成相关的分子机制开辟了新途径。
