Temporal regulation of cyclin A-p107 and p33cdk2 complexes binding to a human thymidine kinase promoter element important for G1-S phase transcriptional regulation.
Temporal regulation of cyclin A-p107 and p33cdk2 complexes binding to a human thymidine kinase promoter element important for G1-S phase transcriptional regulation.
复制标题
细胞周期蛋白 A-p107 和 p33cdk2 复合物与人胸苷激酶启动子元件结合的时间调节，对 G1-S 期转录调节很重要。
DOI：
10.1073/pnas.90.8.3554
复制
发表时间：
1993
影响因子：
11.1
通讯作者：
Lee,AS
中科院分区：
文献类型：
--
作者：
Li,LJ;Naeve,GS;Lee,AS
细胞周期蛋白是一个广泛的蛋白质家族，其细胞周期依赖性合成被假定控制细胞周期期间的多个事件。A型细胞周期蛋白的合成始于S期的开始。在哺乳动物细胞中，与cdc型激酶的关联表明，细胞周期蛋白A复合物对DNA复制和调节S期所需的其他DNA结合底物很重要。我们在这里报告，一个25-bp的启动子元件先前被证明是重要的G1-S激活的人胸苷激酶（htk）启动子在生长刺激的细胞是细胞周期蛋白A和p33 cdk 2复合物的细胞目标。虽然p33 cdk 2和其他核因子复合物表现出与htk G1-S调节结构域的组成性结合，但当细胞进入S期时，细胞周期蛋白A/p107蛋白复合物的结合活性大大增强，这与tk mRNA水平和DNA复制的增加相关。细胞周期蛋白A复合物的结合活性在整个S期维持。在25-bp蛋白结合位点的任何一半上的DNA序列的突变导致其在体外有效竞争htk复合物的能力的丧失，包括含细胞周期蛋白A的复合物的能力。对htk复合物的高亲和力结合的丧失也显著降低了体内htk启动子的S期调节。我们的研究结果支持的假设，一个周期蛋白A复合物，与p33 cdk 2激酶，介导的S期调节的htk启动子在生长刺激的细胞转录。
The cyclins are an extensive family of proteins whose cell cycle-dependent synthesis is postulated to control multiple events during the cell cycle. The synthesis of A-type cyclins begins at the start of S phase. In mammalian cells, association with the cdc-type kinases suggests that cyclin A complexes are important for DNA replication and regulating other DNA-bound substrates required for S phase. We report here that a 25-bp promoter element previously shown to be important for the G1-S activation of the human thymidine kinase (htk) promoter in growth-stimulated cells is a cellular target of cyclin A and the p33cdk2 complexes. Though the p33cdk2 and other nuclear factor complexes exhibit constitutive binding to the htk G1-S regulatory domain, the binding activity of a cyclin A/p107 protein complex is greatly enhanced when the cells enter S phase, correlating with the increase in the tk mRNA levels and the replication of DNA. The binding activity of the cyclin A complex is maintained throughout S phase. Mutation of the DNA sequences on either half of the 25-bp protein binding site results in the loss of its ability to compete efficiently in vitro for the htk complexes, including that of cyclin A-containing complex. The loss of high-affinity binding for the htk complexes also substantially reduces the S-phase regulation of the htk promoter in vivo. Our results support the hypothesis that a cyclin A complex, in association with the p33cdk2 kinase, mediates the S-phase-regulated transcription of the htk promoter in growth-stimulated cells.