Linebaugh B E, Rillema J A
Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan.
Horm Metab Res. 1991 Sep;23(9):414-22. doi: 10.1055/s-2007-1003716.
The actions of prolactin on the rate of synthesis of an isoelectrically precipitable (pH 4.6) phosphoprotein fraction of the MCF-7 human mammary epithelial cell line were determined in cells synchronized at the G1:S interphase of the cell cycle employing hydroxyurea in a serum-free defined medium. Cells not allowed to enter the S-phase of DNA replication, by maintaining hydroxyurea in the incubation medium, exhibited an increased rate of [3H] leucine incorporation into the isoelectrically precipitable phosphoprotein fraction when exposed to prolactin and 1-5 mM spermidine. Cells released from the hydroxyurea induced synchrony exhibited an increased rate of [3H] leucine incorporation in response to prolactin when ornithine, putrescine, or spermidine were present. The polyamine spermine was ineffective in allowing prolactin's action on phosphoprotein synthesis. In synchronized cells released from the hydroxyurea block, prolactin was shown to effect an increased rate of phosphoprotein synthesis at the posttranscriptional G1 stage of the cell cycle. All prolactin responses were attained with physiological concentrations of the hormone. During and subsequent to the synchrony period with hydroxyurea, the presence or absence of insulin was found to be useful for the "staging" of the cell cycle to maintain cell synchrony and obtain prolactin effects on phosphoprotein synthesis.
在无血清限定培养基中使用羟基脲使MCF-7人乳腺上皮细胞系同步于细胞周期的G1:S间期，以此测定催乳素对一种等电点可沉淀（pH 4.6）磷蛋白组分合成速率的作用。通过在孵育培养基中维持羟基脲，不允许细胞进入DNA复制的S期，当暴露于催乳素和1 - 5 mM亚精胺时，这些细胞显示出[3H]亮氨酸掺入等电点可沉淀磷蛋白组分的速率增加。当存在鸟氨酸、腐胺或亚精胺时，从羟基脲诱导的同步化中释放的细胞对催乳素的反应表现出[3H]亮氨酸掺入速率增加。多胺精胺在使催乳素作用于磷蛋白合成方面无效。在从羟基脲阻断中释放的同步化细胞中，催乳素显示在细胞周期的转录后G1期影响磷蛋白合成速率增加。所有催乳素反应都是在该激素的生理浓度下实现的。在与羟基脲同步化期间及之后，发现胰岛素的存在与否对于细胞周期的“分期”以维持细胞同步化以及获得催乳素对磷蛋白合成的作用是有用的。
