The cyclin-dependent kinase inhibitor p27Kip1 is localized to the cytosol in Swiss/3T3 cells.
The cyclin-dependent kinase inhibitor p27Kip1 is localized to the cytosol in Swiss/3T3 cells.
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细胞周期蛋白依赖性激酶抑制剂 p27Kip1 定位于 Swiss/3T3 细胞的细胞质中。
DOI：
10.1038/sj.onc.1202912
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发表时间：
1999
期刊：
影响因子：
8
通讯作者：
Miskimins,WK
中科院分区：
文献类型：
--
作者：
Wang,G;Miskimins,R;Miskimins,WK
p27 Kip 1通过负性调节cyclin-Cdk复合物的活性在细胞周期进程中起重要作用。为了了解p27 Kip 1如何发挥功能，检测了血清刺激静止细胞后Swiss/3 T3细胞中p27 Kip 1的水平和亚细胞定位。令人惊讶的是，p27 Kip 1被观察到专门在整个G1和早期S期的细胞质。然而，正如预期的那样，p27 Kip 1在胞质组分大大减少血清刺激后，并达到非常低的水平，晚G1。p27 Kip 1水平的下降与Cdk 2和细胞周期蛋白E的核水平的增加相对应。在静止的3 T3细胞中，Cdk 2是无活性的，并且与p27 Kip 1共沉淀。血清刺激后，细胞核和胞质Cdk 2被激活，这对应于p27 Kip 1的下降。p27 Kip 1的过表达允许在细胞核中的抑制剂的积累，但抑制Cdk 2进入细胞核后血清刺激。p27 Kip 1的亚细胞定位也在各种其他哺乳动物细胞中进行了研究。在所有检查的细胞系中，p27 Kip 1的优势被发现在胞质组分中。然而，在几种细胞系中观察到核p27 Kip 1的显著水平。在原代混合神经胶质细胞培养中，p27 Kip 1定位于细胞核。结果表明，胞浆p27 Kip 1在调节细胞周期进程中具有功能性作用，可能通过抑制细胞周期蛋白E-Cdk 2复合物转运到细胞核中。
p27 Kip1 plays an important role in cell cycle progression by negatively regulating the activity of cyclin-Cdk complexes. To understand how p27 Kip1 functions, the level and subcellular location of p27 Kip1 in Swiss/3T3 cells following serum stimulation of quiescent cells was examined. Surprisingly, p27 Kip1 was observed exclusively in the cytosol throughout G1 and into early S phase. However, as expected, p27 Kip1 in the cytosolic fraction was greatly reduced following serum stimulation and reached very low levels by late G1. The decline in the level of p27 Kip1 corresponded in time to an increase in the nuclear level of both Cdk2 and cyclin E. In quiescent 3T3 cells Cdk2 was inactive and co-precipitated with p27 Kip1. After serum stimulation, both nuclear and cytosolic Cdk2 was activated and this corresponded to the decline in p27 Kip1. Overexpression of p27 Kip1 allowed accumulation of the inhibitor in the nucleus but inhibited entry of Cdk2 into the nucleus following serum stimulation. The subcellular localization of p27 Kip1 was also examined in a variety of other mammalian cells. In all the cell lines examined the preponderance of p27 Kip1 was found in the cytosolic fraction. However, a substantial level of nuclear p27 Kip1 was observed for several cell lines. In a primary mixed glial cell culture p27 Kip1 was localized to the nucleus. The results suggest that cytosolic p27 Kip1 has a functional role in regulating cell cycle progression, possibly through inhibiting transport of cyclin E-Cdk 2 complexes into the nucleus.