G1 cyclin/cyclin-dependent kinase-coordinated phosphorylation of endogenous pocket proteins differentially regulates their interactions with E2F4 and E2F1 and gene expression
G1 cyclin/cyclin-dependent kinase-coordinated phosphorylation of endogenous pocket proteins differentially regulates their interactions with E2F4 and E2F1 and gene expression
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DOI：
10.1074/jbc.m209181200
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发表时间：
2002-12-27
影响因子：
4.8
通讯作者：
Graña, X
中科院分区：
文献类型：
--
作者：
Calbó, J;Parreño, M;Graña, X
促有丝分裂刺激导致G（1）细胞周期蛋白依赖性激酶（CDK）的激活，其磷酸化口袋蛋白并通过细胞周期的G（0）/G（1）和G（1）/S转变触发进展。然而，G（1）细胞周期蛋白-CDK复合物在口袋蛋白的协调调节及其与E2 F家族成员的相互作用中的单独作用尚未完全了解。在这里，我们报告说，单独或在演唱会细胞周期蛋白D1-CDK和细胞周期蛋白E-CDK复合物诱导内源性口袋蛋白，这也有不同的后果，口袋蛋白与E2 F4和p107和E2 F1，E2 F调节基因的表达的相互作用的调节独特和协调的磷酸化。这两种蛋白质的上调以及p130和pRB从E2 F4复合物中的释放允许不仅与pRB而且与p130和p107形成E2 F1复合物以及形成p107-E2 F4复合物。这些复合物的形成发生在活性细胞周期蛋白D1-CDK和细胞周期蛋白E-CDK复合物的存在下，表明磷酸化在消除某些口袋蛋白/E2 F相互作用中起作用，这些相同的活性在表达内源性口袋和E2 F蛋白的细胞的背景下诱导其他复合物的形成。值得注意的是，不与E2 F4相互作用的磷酸化p130“形式3”容易与E2 F1相互作用。我们的数据还表明，异位过表达的细胞周期蛋白是足以诱导有丝分裂原的非依赖性生长在人类T98 G和大鼠-1细胞，虽然细胞周期蛋白D1的影响需要下游激活的细胞周期蛋白E-CDK 2活性。有趣的是，在T98 G细胞中，细胞周期蛋白D1比细胞周期蛋白E更有效地诱导细胞周期进展。这表明细胞周期蛋白D1独立于细胞周期蛋白E激活途径，确保细胞周期的及时进展。
Mitogenic stimulation leads to activation of G(1) cyclin-dependent kinases (CDKs), which phosphorylate pocket proteins and trigger progression through the G(0)/G(1) and G(1)/S transitions of the cell cycle. However, the individual role of G(1) cyclin-CDK complexes in the coordinated regulation of pocket proteins and their interaction with E2F family members is not fully understood. Here we report that individually or in concert cyclin D1-CDK and cyclin E-CDK complexes induce distinct and coordinated phosphorylation of endogenous pocket proteins, which also has distinct consequences in the regulation of pocket protein interactions with E2F4 and the expression of p107 and E2F1, both E2F-regulated genes. The up-regulation of these two proteins and the release of p130 and pRB from E2F4 complexes allows formation of E2F1 complexes not only with pRB but also with p130 and p107 as well as the formation of p107-E2F4 complexes. The formation of these complexes occurs in the presence of active cyclin D1-CDK and cyclin E-CDK complexes, indicating that whereas phosphorylation plays a role in the abrogation of certain pocket protein/E2F interactions, these same activities induce the formation of other complexes in the context of a cell expressing endogenous levels of pocket and E2F proteins. Of note, phosphorylated p130 "form 3," which does not interact with E2F4, readily interacts with E2F1. Our data also demonstrate that ectopic overexpression of either cyclin is sufficient to induce mitogen-independent growth in human T98G and Rat-1 cells, although the effects of cyclin D1 require downstream activation of cycilin E-CDK2 activity. Interestingly, in T98G cells, cyclin D1 induces cell cycle progression more potently than cyclin E. This suggests that cyclin D1 activates pathways independently of cyclin E that ensure timely progression through the cell cycle.