Miyashita T, Nagao K, Ohmi K, Yanagisawa H, Okamura-Oho Y, Yamada M
Department of Genetics, National Children's Medical Research Center, Tokyo, Japan.
Biochem Biophys Res Commun. 1998 Aug 10;249(1):96-102. doi: 10.1006/bbrc.1998.9096.
Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder caused by the abnormal CAG triplet-repeat expansion resulting in an elongated polyglutamine (polyQ) stretch. We have recently showed that the DRPLA protein is cleaved during apoptosis by caspase-3, one of the cysteine protease family members known to be activated during apoptosis. We report here the subcellular localization of the DRPLA protein by fusing the green fluorescent protein as a tag. The full length DRPLA protein is localized predominantly but not exclusively in the nucleus regardless of the length of the polyQ stretch. In contrast, an N-terminal-deleted fragment containing polyQ produced by the proteolytic cleavage with caspase-3 is found both in the nucleus and the cytoplasm. Moreover, the same fragment with the elongated polyQ showed aggregation when overexpressed. Some cells with aggregate formation showed apoptotic phenotype. These findings raise the possibility that the DRPLA protein processed by caspase-3 may lead to aggregation of the protein resulting in the development of neurodegeneration.
齿状核红核苍白球路易体萎缩症（DRPLA）是一种常染色体显性神经退行性疾病，由异常的CAG三联体重复扩增引起，导致多聚谷氨酰胺（polyQ）链延长。我们最近发现，DRPLA蛋白在凋亡过程中被半胱天冬酶-3切割，半胱天冬酶-3是已知在凋亡过程中被激活的半胱氨酸蛋白酶家族成员之一。我们在此报告通过融合绿色荧光蛋白作为标签对DRPLA蛋白进行亚细胞定位。无论polyQ链的长度如何，全长DRPLA蛋白主要定位于细胞核，但并非完全定位于细胞核。相反，通过半胱天冬酶-3蛋白水解切割产生的含有polyQ的N端缺失片段在细胞核和细胞质中均有发现。此外，具有延长的polyQ的相同片段在过表达时会发生聚集。一些形成聚集物的细胞表现出凋亡表型。这些发现增加了一种可能性，即被半胱天冬酶-3加工的DRPLA蛋白可能导致蛋白质聚集，从而导致神经退行性变的发展。
