Cyclin-dependent kinase 5 phosphorylates and induces the degradation of ataxin-2
Cyclin-dependent kinase 5 phosphorylates and induces the degradation of ataxin-2
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DOI：
10.1016/j.neulet.2014.01.046
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发表时间：
2014-03-20
影响因子：
2.5
通讯作者：
Hisanaga, Shin-ichi
中科院分区：
文献类型：
--
作者：
Asada, Akiko;Yamazaki, Rena;Hisanaga, Shin-ichi
共济失调蛋白-2蛋白内polyQ重复序列的扩增导致脊髓小脑共济失调2型（SCA 2）。然而，共济失调蛋白-2的确切病理机制和生理功能尚不清楚。共济失调蛋白-2含有47个（S/T）P序列，其被脯氨酸导向的蛋白激酶如细胞周期蛋白依赖性激酶5（Cdk 5）靶向。我们假设共济失调蛋白-2被Cdk 5磷酸化。事实上，Cdk 5-p25对共济失调蛋白-2的磷酸化可以通过两种方法来证明：体外P-32标记和Phos标记的SDS-PAGE电泳迁移率改变。将共济失调蛋白2分级分离成三个部分，N-末端片段（NF，氨基酸1-507）、中间片段（MF，氨基酸508-905）和C-末端片段（CF，氨基酸906-1313），表明当在COS-7细胞中表达时，NF和MF分别被Cdk 5-p25轻度和高度磷酸化。Cdk 5介导的磷酸化可显著诱导NF降解，中度诱导MF降解。此外，毒性ataxin-2- 41 Q在Cdk 5磷酸化后进行蛋白酶体降解。这些结果表明，Cdk 5控制神经元中正常和polyQ扩增的共济失调蛋白-2蛋白的丰度，这意味着Cdk 5活性是SCA 2的治疗方法。(C)2014爱思唯尔爱尔兰有限公司版权所有。
The expansion of a polyQ repeat within the ataxin-2 protein causes spinocerebellar ataxia type 2 (SCA2). However, neither the precise pathological mechanism nor the physiological functions of ataxin-2 are known. Ataxin-2 contains 47 (S/T)P sequences, which are targeted by praline-directed protein kinases such as the cyclin-dependent kinase 5 (Cdk5). We hypothesized that ataxin-2 is phosphorylated by Cdk5. In fact, phosphorylation of ataxin-2 by Cdk5-p25 was shown using two methods: in vitro P-32 labeling and electrophoretic mobility shift on Phos-tag SDS-PAGE. The fractionation of ataxin-2 into three portions, the N-terminal fragment (NF, amino acids 1-507), the middle fragment (MF, amino acids 508-905), and the C-terminal fragment (CF, amino acids 906-1313) showed that NF and MF were phosphorylated slightly and highly, respectively, by Cdk5-p25 when expressed in COS-7 cells. Cdk5-mediated phosphorylation induced the degradation of NF remarkably and MF moderately. Furthermore, toxic ataxin-2-41Q under-went proteasomal degradation after phosphorylation by Cdk5. These results suggest that Cdk5 controls the abundance of both normal and polyQ-expanded ataxin-2 protein in neurons, which implies that Cdk5 activity is a therapeutic approach for SCA2. (C) 2014 Elsevier Ireland Ltd. All rights reserved.