Transforming growth factor-beta induces Cdk2 relocalization to the cytoplasm coincident with dephosphorylation of retinoblastoma tumor suppressor protein.
Transforming growth factor-beta induces Cdk2 relocalization to the cytoplasm coincident with dephosphorylation of retinoblastoma tumor suppressor protein.
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DOI：
10.1186/bcr762
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Law BK
中科院分区：
文献类型：
--
作者：
Brown KA;Roberts RL;Arteaga CL;Law BK
转化生长因子-β（TGF-β）信号通路的作用是预防肿瘤发生，并且对TGF-β介导的细胞周期停滞的敏感性丧失在人类癌症中几乎普遍存在。我们以前的研究表明，雷帕霉素加强TGF-β诱导的非转化上皮细胞的细胞周期阻滞，并部分恢复TGF-β诱导的某些人癌细胞系的生长停滞。生长停滞与p21和p27与细胞周期蛋白依赖性激酶2（Cdk 2）的结合增加以及Cdk 2激酶活性抑制相关。然而，目前尚不清楚TGF-β如何引起p21和p27与Cdk 2的结合增加。进行细胞分级分离和免疫荧光显微镜实验以检查TGF-β对Cdk 2、p21和p27的细胞内定位的影响。对细胞质和细胞核提取物进行激酶测定，以确定TGF-β如何改变两个亚细胞区室中的Cdk 2活性。在乳腺上皮细胞中，用TGF-β处理诱导了细胞核Cdk 2浓度的降低和Cdk 2向细胞质的重新定位。Cdk 2重新定位到细胞质与核视网膜母细胞瘤肿瘤抑制蛋白的去磷酸化和核Cdk 2活性降低相关。在这些上皮细胞系中，p21和p27主要定位于细胞质中。细胞核Cdk 2浓度的降低与Cdk 2与细胞质p21和p27的结合增加相关。通过TGF-β +雷帕霉素处理诱导的协同生长停滞通过多种机制引起细胞核Cdk 2活性的抑制，包括Cdk 2重新定位到细胞质，增加p27和p21与Cdk 2的结合，以及增加细胞核Cdk 2在其抑制位点Tyr 15上的磷酸化。
The transforming growth factor-β (TGF-β) signaling pathway functions to prevent tumorigenesis, and loss of sensitivity to TGF-β-mediated cell cycle arrest is nearly ubiquitous among human cancers. Our previous studies demonstrated that rapamycin potentiates TGF-β-induced cell cycle arrest in nontransformed epithelial cells and partially restores TGF-β-induced growth arrest of some human cancer cell lines. Growth arrest correlated with increased binding of p21 and p27 to cyclin-dependent kinase-2 (Cdk2), and inhibition of Cdk2 kinase activity. However, it was unclear how TGF-β caused increased binding of p21 and p27 to Cdk2. Cell fractionation and immunofluorescence microscopy experiments were performed to examine the effect of TGF-β on the intracellular localization of Cdk2, p21, and p27. Kinase assays were performed on cytoplasmic and nuclear extracts to determine how TGF-β altered Cdk2 activity in both subcellular compartments. In breast epithelial cells treatment with TGF-β induced a decrease in nuclear Cdk2 concentrations and relocalization of Cdk2 to the cytoplasm. Cdk2 relocalization to the cytoplasm correlated with dephosphorylation of nuclear retinoblastoma tumor suppressor protein and decreased nuclear Cdk2 activity. In these epithelial cell lines, p21 and p27 were localized primarily in the cytoplasm. Decreases in nuclear Cdk2 concentrations correlated with increased binding of Cdk2 to cytoplasmic p21 and p27. Cooperative growth arrest induced by treatment with TGF-β + rapamycin causes inhibition of nuclear Cdk2 activity through multiple mechanisms, including Cdk2 relocalization to the cytoplasm, increased p27 and p21 binding to Cdk2, and increased phosphorylation of nuclear Cdk2 on its inhibitory site, Tyr15.
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DOI：
10.1073/pnas.94.10.4948
发表时间：
1997-05-13
影响因子：
11.1
作者：
Li, JM;Hu, PPC;Wang, XF
通讯作者：
Wang, XF
影响因子：
3.8
作者：
Bresnahan, WA;Thompson, EA;Albrecht, T
通讯作者：
Albrecht, T
DOI：
10.1073/pnas.92.8.3239
发表时间：
1995-04-11
影响因子：
11.1
作者：
ALEXANDROW, MG;KAWABATA, M;MOSES, HL
通讯作者：
MOSES, HL
影响因子：
64.5
作者：
Geng, Y;Yu, QY;Sicinski, P
通讯作者：
Sicinski, P
影响因子：
8
作者：
Cipriano, SC;Chen, YQ
通讯作者：
Chen, YQ