Dp71 is regulated by phosphorylation and ubiquitin-proteasome system in neuronal cells
Dp71 is regulated by phosphorylation and ubiquitin-proteasome system in neuronal cells
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DOI：
10.1016/j.bbrc.2017.08.108
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发表时间：
2017-10-21
影响因子：
3.1
通讯作者：
Itoh, Kyoko
中科院分区：
文献类型：
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作者：
Fujimoto, Takahiro;Yaoi, Takeshi;Itoh, Kyoko
Dystrophin（Dp）基因导致杜氏肌营养不良症（DMD），其特征在于进行性肌肉变性和不同程度的认知障碍。虽然Dp 71是脑中含量最丰富的Dp亚型，但其相关表达水平的调控机制尚未阐明。在这项研究中，我们发现PC 12细胞中Dp 71的组成性表达水平对蛋白酶体抑制敏感。FLAG标记的泛素的异位表达揭示了Dp 71在细胞内被泛素化。有趣的是，蛋白酶体抑制伴随着翻译后积累的修改Dp 71，这是恢复蛋白磷酸酶处理在体外，表明磷酸化是负责的修改和影响蛋白酶体依赖性降解Dp 71。蛋白酶体活性敏感的磷酸化Dp 71与Dp 71的结合伴侣syntrophin密切相关，syntrophin也以类似于Dp 71的方式受到蛋白酶体活性的调节，这表明Dp 71水平的翻译后调节机制与Dp 71-syntrophin分子复合物偶联。综上所述，我们的研究结果表明，Dp 71的表达水平是由磷酸化-泛素-蛋白酶体途径后调节，这可能表明Dp及其分子复合物的蛋白稳态的调节机制的存在，这可能导致更好的治疗方法用于治疗Dp相关疾病。(C)2017爱思唯尔公司All rights reserved.
The Dystrophin (Dp) gene is responsible for Duchenne muscular dystrophy (DMD), which is characterized by progressive muscular degeneration and variable degrees of cognitive impairment. Although Dp71 is the most abundant among the Dp isoforms in the brain, the regulatory mechanisms of the related expression levels have not been elucidated. In this study, we found that the constitutive expression levels of Dp71 in PC12 cells were sensitive to proteasomal inhibition. The ectopic expression of FLAG -tagged ubiquitin revealed that Dp71 was ubiquitinated intracellularly. Interestingly, proteasomal inhibition was accompanied by a posttranslational accumulation of modified Dp71, which was restored by protein phosphatase treatment in vitro, indicating that phosphorylation is responsible for the modification and affects the proteasome-dependent degradation of Dp71. Proteasomal activity-sensitive phosphorylated Dp71 is closely associated with syntrophin, a well-known binding partner of Dp71, and syntrophin is also regulated by proteasomal activity in a similar way to Dp71, suggesting that the posttranslational regulatory machinery for Dp71 level is coupled with Dp71-syntrophin molecular complex. Taken together, our results indicated that the expression levels of Dp71 are posttranslationally regulated by the phosphorylation-ubiquitin-proteasomal pathway, which may indicate the presence of regulatory mechanisms underlying the proteostasis of both Dp and its molecular complex, which may lead to better therapeutic approaches for the treatment of Dp-related diseases. (C) 2017 Elsevier Inc. All rights reserved.