Mitotic phosphorylation of Aki1 at Ser208 by cyclin B1-Cdk1 complex.
Mitotic phosphorylation of Aki1 at Ser208 by cyclin B1-Cdk1 complex.
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DOI：
10.1016/j.bbrc.2010.02.103
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发表时间：
2010-03
影响因子：
3.1
通讯作者：
A. Nakamura;M. Naito;H. Arai;N. Fujita
中科院分区：
文献类型：
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作者：
A. Nakamura;M. Naito;H. Arai;N. Fujita
Akt 激酶相互作用蛋白 1 (Aki1)/Freud-1/CC2D1A 位于细胞质、细胞核和中心体中。 Aki1 根据其定位发挥不同的作用。在胞质溶胶中，它充当磷酸肌醇 3-激酶 (PI3K)/3-磷酸肌醇依赖性蛋白激酶 1 (PDK1)/Akt 通路中的支架蛋白。在细胞核中，它是 5-羟色胺-1A (5-HT1A) 受体的转录抑制因子。在中心体中，它调节粘连蛋白亚基 Scc1 的纺锤体极定位，从而介导有丝分裂期间的中心粒粘聚力。尽管 Aki1 的功能已得到很好的阐明，但对 Aki1 的调控机制却知之甚少。我们之前发现有丝分裂细胞中的 Aki1 在免疫印迹分析中表现出迁移性降低，但其原因尚不清楚。在这里，我们证明 Aki1 的电泳迁移率变化源自有丝分裂磷酸化。细胞周期蛋白 B1-细胞周期蛋白依赖性激酶 1 (Cdk1) 复合物被发现是有丝分裂期间负责 Aki1 磷酸化的激酶之一。我们将 Aki1 的 Ser208 残基鉴定为细胞周期蛋白 B1-Cdk1 磷酸化位点。此外，细胞周期蛋白 B1-Cdk1 抑制剂处理可减弱 Aki1 与 Scc1 复合物的水平，表明细胞周期蛋白 B1-Cdk1 导致的 Aki1 磷酸化有助于 Aki1-Scc1 复合物的形成。我们的结果表明，cyclin B1–Cdk1 是有丝分裂过程中 Aki1 的激酶，其 Aki1 的磷酸化可能调节有丝分裂功能。
Akt kinase-interacting protein 1 (Aki1)/Freud-1/CC2D1A is localized in the cytosol, nucleus, and centrosome. Aki1 plays distinct roles depending on its localization. In the cytosol, it acts as a scaffold protein in the phosphoinositide 3-kinase (PI3K)/3-phosphoinositide-dependent protein kinase 1 (PDK1)/Akt pathway. In the nucleus, it is a transcriptional repressor of the serotonin-1A (5-HT1A) receptor. In the centrosome, it regulates spindle pole localization of the cohesin subunit Scc1, thereby mediating centriole cohesion during mitosis. Although the function of Aki1 has been well clarified, the regulatory machinery of Aki1 is poorly understood. We previously found that Aki1 in mitotic cells displayed reduced mobility on immunoblot analysis, but the reason for this was unclear. Here we show that the electrophoretic mobility shift of Aki1 is derived from mitotic phosphorylation. The cyclin B1–cyclin-dependent kinase 1 (Cdk1) complex was found to be one of the kinases responsible for Aki1 phosphorylation during mitosis. We identified the Ser208residue of Aki1 as a cyclin B1–Cdk1 phosphorylation site. Furthermore, cyclin B1–Cdk1 inhibitor treatment was shown to attenuate the level of Aki1 in complex with Scc1, suggesting that Aki1 phosphorylation by cyclin B1–Cdk1 contributes to Aki1–Scc1 complex formation. Our results indicate that cyclin B1–Cdk1 is a kinase of Aki1 during mitosis and that its phosphorylation of Aki1 may regulate mitotic function.