Inhibition of Akt kinase activity by a peptide spanning the βA strand of the proto-oncogene TCL1
Inhibition of Akt kinase activity by a peptide spanning the βA strand of the proto-oncogene TCL1
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DOI：
10.1074/jbc.m403775200
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发表时间：
2004-12-17
影响因子：
4.8
通讯作者：
Noguchi, M
中科院分区：
文献类型：
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作者：
Hiromura, M;Okada, F;Noguchi, M
Akt在多种人类肿瘤疾病的细胞抗凋亡调控中起核心作用。我们之前已经证明TCL1（人类T细胞前淋巴细胞白血病的原癌基因）与Akt相互作用，并作为Akt激酶共激活剂发挥作用。为了开发一种Akt激酶抑制剂，我们假设一种跨越Akt结合位点的肽与Akt结合并调节Akt激酶活性及其下游生物反应。事实上，我们证明了一种名为“Akt-in”的肽（Akt抑制剂，NH2-AVTDHPDRLWAWEKFCOOH，包含人TCL1的β - aa链）与Akt相互作用并特异性抑制其激酶活性。核磁共振研究表明，Akt-in与Akt的pleckstrin同源结构域（PH）相互作用导致Akt可变环1的构象改变，该位点介导磷酸肌苷结合。同样，Akt-in与Akt PH结构域的相互作用阻止了磷酸肌苷的结合，从而抑制了Akt的膜转运和活化。此外，Akt-in不仅在体外抑制细胞增殖和抗凋亡，而且在体内抑制肿瘤生长，无不良反应。具有PH结构域的Akt在细胞内信号传导中的作用已得到证实。因此，Akt抑制剂为抗癌治疗创造了一个有吸引力的靶点。然而，目前还没有开发出针对Akt的有效抑制剂。Akt-in可以抑制磷脂酰肌醇与Akt的结合，是第一个显示出特异性Akt激酶抑制能力的分子。这一观察结果将有助于设计针对Akt的特异性抑制剂，Akt是多种人类肿瘤疾病的核心细胞内生存因子。
Akt plays a central role in the regulation of cellular anti-apoptosis underlying various human neoplastic diseases. We have demonstrated previously that TCL1 ( a proto-oncogene underlying human T cell prolymphocytic leukemia) interacts with Akt and functions as an Akt kinase co-activator. With the aim to develop an Akt kinase inhibitor, we hypothesized that a peptide, which spans the Akt-binding site, binds to Akt and modulates Akt kinase activity and its downstream biological responses. Indeed, we demonstrated that a peptide, named "Akt-in" (Akt inhibitor, NH2-AVTDHPDRLWAWEKFCOOH, encompassing the betaA strand of human TCL1), interacted with Akt and specifically inhibited its kinase activity. Nuclear magnetic resonance studies suggested that interaction of Akt-in with the pleckstrin homology domain (PH) of Akt caused conformational changes on the variable loop 1 of Akt, the locus mediating phosphoinositide binding. Consistently, interaction of Akt-in with the Akt PH domain prevented phosphoinositide binding and hence inhibited membrane translocation and activation of Akt. Moreover, Akt-in inhibited not only cellular proliferation and anti-apoptosis in vitro but also in vivo tumor growth without any adverse effect. The roles of Akt, which possesses a PH domain, in intracellular signaling were well established. Hence, Akt inhibitors create an attractive target for anticancer therapy. However, no effective inhibitors specific for Akt have been developed. Akt-in, which inhibits association of phosphatidylinositol with Akt, is the first molecule to demonstrate specific Akt kinase inhibition potency. This observation will facilitate the design of specific inhibitors for Akt, a core intracellular survival factor underlying various human neoplastic diseases.