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Apoptotic dell death through lipid kinase/PKB/AFX and stress signaling pathways

通过脂质激酶/PKB/AFX和应激信号通路导致细胞凋亡

基本信息

批准号：
14370059
负责人：
KIKKAWA Ushio
金额：
$ 9.02万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14370059/
关键词：
Protein kinase PKB Growth factor Heat shock Transcription factor AFX Apoptosis Hsp27 ストレス刺激リン酸化部位特異的抗体

项目摘要

PKB is a downstream target of PI 3-kinase in the growth factor-signaling pathway. It is proposed that AFX, a forkhead transcription factor, is phosphorylated by PKB, and that AFX localizes in cytosol while phosphorylated and is translocated into cell nucleus, when dephosphorylated, to induce apoptosis. We revealed that two residues of three phosphorylation consensus sites by PKB in AFX, such as Thr32, Ser197, and Ser262, are phosphorylated, and that Ser197 is dephosphorylated immediately after the removal of growth factors in cells by the analysis of point mutants using the phosphorylation site-specific antibodies. On the other hand, we had shown that PKB is activated by heat shock, and thus compared the activation mechanisms of PKB by growth factor and heat shock. It was shown that heat shock generates the active form of PKB in a manner independent of PI 3-kinase without phosphorylation of PKB, which is essential for growth factor-induced activation of the enzyme. It has been established that PKB is recruited to the plasma membrane from cytosol through its PH domain upon growth factor stimulation. In contrast, we revealed that PKB is accumulated in the perinuclear region by the association with Hsp27, a low molecular chaperon protein, in heat-shocked cells. Therefore, PKB is supposed to be activated by different mechanisms to prevent apoptosis by inhibiting the nuclear translocation of AFX. Furthermore, it was shown that PKC, having the catalytic domain highly homologous to that of PKB, is activated by stress signal and enhances apoptosis presumably through the regulation of some lipid metabolizing enzymes. It is necessary to analyze the targets of PKB and PKC in the regulation of stress-induced apoptosis.

PKB是生长因子信号通路中PI 3-激酶的下游靶点。有人提出，AFX，叉头转录因子，被PKB磷酸化，AFX定位在细胞质中，而磷酸化和易位到细胞核中，当去磷酸化，诱导凋亡。我们发现，两个残基的三个磷酸化共识网站的PKB在AFX，如Thr 32，Ser 197，和Ser 262，磷酸化，Ser 197是去磷酸化后，立即去除细胞中的生长因子的点突变体的分析，使用磷酸化位点特异性抗体。另一方面，我们已经证明PKB是由热休克激活的，从而比较了生长因子和热休克激活PKB的机制。结果表明，热休克产生活性形式的PKB的方式独立于PI 3-激酶没有磷酸化的PKB，这是必不可少的生长因子诱导的酶的激活。已经确定，在生长因子刺激后，PKB通过其PH结构域从胞质溶胶募集到质膜。与此相反，我们发现，PKB积累在核周区的协会与热休克蛋白27，低分子伴侣蛋白，在热休克细胞。因此，PKB可能通过不同的机制被激活，通过抑制AFX的核转位来防止细胞凋亡。此外，研究表明，PKC具有与PKB的催化结构域高度同源的催化结构域，其被应激信号激活，并可能通过调节一些脂质代谢酶来促进细胞凋亡。因此，有必要分析PKB和PKC在应激诱导细胞凋亡调控中的作用靶点。