Involvement of CK2 for the nuclear dynamic function during the progression of cell cycle.

CK2 在细胞周期进展过程中参与核动态功能。

基本信息

批准号：
20570137
负责人：
HOMMA MiwakoK.
金额：
$ 3.16万
依托单位：
Fukushima Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

项目摘要

Protein kinase CK2 is a highly conserved serine/threonine kinase that functions in multiple cellular processes including cell growth and development. It is typically found in tetrameric complexes consisting of two catalytic α and/or α' subunits, and two regulatory β subunits. We reported the cell-cycle dependent association of CK2 with adenomatous polyposis coli (APC) that regulates CK2 activity, and identified its downstream target as eukaryotic translation initiation factor 5 (eIF5). Here we demonstrate that a pool of CK2α subunits translocate into the nucleus in G1 phase of the cell cycle, when serum-starved normal human fibroblasts are simulated by FBS, whereas the β subunits localize to the nuclear fraction later than α. Translocation of αβ subunits associate with enhanced phosphorylation of these molecules. Pretreatment with a potent ATP competitive inhibitors reduce nuclear localization of CK2α after FBS stimuli. Similarly, phosphorylation site mutants in CK2α partially inhibit their accumulation in the nuclear fraction following FBS stimuli. These results suggest the involvement of multiple kinases that phosphorylate CK2 for the growth factor-induced nuclear localization. Co-immunoprecipitation experiments using anti-CK2α antibodies, followed by mass spectrometry analysis, identified nuclear proteins that associate with CK2α in a cell -cycle dependent manner. As one of these proteins, hnRNPs is also a phosphoprotein in vivo. FRAP experiments on living stable cell lines expressing GFP-CK2α protein indicate that the nucleocytoplasmic distribution of CK2 subunits may be regulated in a cell cycle-dependent manner. These results support a role for CK2 in response to growth stimuli, and also the possible involvement of CK2α subunit as isolated entities exerting specific functions in complex with other cellular partners in the nuclear fraction, during the progression of cell cycle.

蛋白激酶CK2是一种高度保守的丝氨酸/苏氨酸激酶，在包括细胞生长和发育在内的多种细胞过程中起作用。它通常在由两个催化α和/或α'亚基和两个调节性β亚基组成的四聚体配合物中发现。我们报道了CK2与调节CK2活性的腺瘤性息肉大肠杆菌（APC）的细胞周期依赖性关联，并将其下游靶标确定为真核翻译倡议因子5（EIF5）。在这里，我们证明了CK2α亚基在细胞周期的G1阶段中转移到核us库时，当血清饥饿的正常人成纤维细胞由FBS模拟时，而β亚基则与α晚于α的核分数定位于α。 αβ亚基的转运与这些分子的磷酸化相关。具有潜在ATP竞争抑制剂的预处理减少了FBS刺激后CK2α的核定位。同样，CK2α中的磷酸化位点突变体在FBS刺激后部分抑制其在核分裂中的积累。这些结果表明，多种激酶会涉及磷酸化CK2以用于生长因子诱导的核定位。使用抗CK2α抗体进行的共免疫沉淀实验，然后进行质谱分析，鉴定出以细胞循环依赖性方式与CK2α相关的核蛋白。作为这些蛋白质之一，HNRNPs也是体内的磷蛋白。对表达GFP-CK2α蛋白的活细胞系进行的FRAP实验表明，CK2亚基的核眼质分布可以以细胞周期依赖性方式调节。这些结果支持CK2对生长刺激的作用，以及CK2α亚基作为孤立的实体的可能参与，在细胞周期的进展过程中，在核分数中与其他细胞伴侣发挥特定功能。