Cytoplasmic localization and proteasomal degradation of N-terminally cleaved form of PINK1
Cytoplasmic localization and proteasomal degradation of N-terminally cleaved form of PINK1
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DOI：
10.1016/j.neulet.2007.10.019
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发表时间：
2008-01-03
影响因子：
2.5
通讯作者：
Iwatsubo, Takeshi
中科院分区：
文献类型：
--
作者：
Takatori, Sho;Ito, Genta;Iwatsubo, Takeshi
PTEN诱导假定激酶1（PINK1）基因的突变与家族性帕金森病的一种常染色体隐性形式有关。PINK1编码一种预测的线粒体蛋白激酶。尽管已有人提出PINK1的线粒体定位，但PINK1发挥其细胞保护功能的确切亚细胞区室仍不清楚。因此，我们研究了培养细胞中PINK1的亚细胞分布和代谢。免疫细胞化学分析表明，PINK1除了存在于线粒体中，还存在于细胞质中，并且其线粒体定位取决于其N末端序列。PINK1的细胞表达产生了几个N末端切割的片段以及全长蛋白，其中在蛋白酶体抑制剂存在的情况下，54 kDa片段（ΔN 54 kDa）高度积累。在内源性PINK1在蛋白酶体抑制时主要以ΔN 54 kDa的形式被检测到。与全长蛋白相比，ΔN 54 kDa的快速周转进一步支持了其对蛋白酶体降解的更高敏感性。这些结果表明，ΔN 54 kDa PINK1通过蛋白酶体进行组成性降解，并强调了其在细胞质中定位的重要性，特别是以N末端加工形式定位的重要性。（c）2007爱思唯尔爱尔兰有限公司。保留所有权利。
Mutations in PTEN-induced putative kinase 1 (PINK1) gene have been linked to an autosomal recessive form of familial Parkinson's disease. PINK1 encodes a predicted mitochondrial protein kinase. Although the mitochondrial localization of PINK1 has been suggested, the exact subcellular compartment in which PINK1 exerts its cytoprotective function is elusive. Thus, we studied the subcellular distribution and metabolism of PINK1 in cultured cells. Immunocytochemical analysis showed that PINK1 resides in cytoplasm in addition to mitochondria, and that the mitochondrial localization is dependent on its N-terminal sequence. Cellular expression of PINK1 yielded several N-terminally cleaved fragments as well as the full-length protein, among which the 54 kDa fragment (Delta N 54 kDa) was highly accumulated in the presence of proteasome inhibitors. Endogenous PINK1 was detected dominantly in the form of Delta N 54 kDa upon proteasome inhibition. Rapid turnover of Delta N 54 kDa further supported its higher susceptibility to proteasomal degradation compared with that of full-length protein. These results indicate that Delta N 54 kDa PINK1 undergoes constitutive degradation by proteasome, and underscore the significance of its localization in cytoplasm, especially in the N-terminally processed form. (c) 2007 Elsevier Ireland Ltd. All rights reserved.