Study of subcellular localization and proteolysis of ataxin-3
Study of subcellular localization and proteolysis of ataxin-3
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DOI：
10.1016/j.nbd.2008.01.011
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发表时间：
2008-05-01
影响因子：
6.1
通讯作者：
Fusi, Paola
中科院分区：
文献类型：
--
作者：
Pozzi, Chiara;Valtorta, Marco;Fusi, Paola
在这项工作中，我们调查亚细胞定位和蛋白水解裂解的不同形式的共济失调蛋白-3（AT-3），负责脊髓小脑共济失调3型蛋白。研究了正常（AT-3Q 6和AT-3Q 26）和病理性（AT-3Q 72）共济失调蛋白-3，以及缺乏poly-Q的两种截短形式。全长蛋白质也表达为C14 A突变体，以评估AT-3自身蛋白水解活性是否参与其片段化。我们发现，正常和病理蛋白定位在细胞质和细胞核中的预期，但也在线粒体。微测序显示，所有共济失调蛋白-3都经历了相同的蛋白水解切割，去除了前27个氨基酸。有趣的是，虽然正常的共济失调蛋白在一些半胱天冬酶位点被进一步裂解，但病理性AT-3的蛋白水解程度要小得多。这可能在发病机制中发挥作用，阻碍易聚集的扩增AT-3的降解。此外，自溶切割显然不参与AT-3蛋白水解。(c)2008年爱思唯尔公司All rights reserved.
In this work we investigate subcellular localization and proteolytic cleavage of different forms of ataxin-3 (AT-3), the protein responsible for spinocerebellar ataxia type 3. Normal (AT-3Q6 and AT-3Q26) and pathological (AT-3Q72) ataxins-3, as well as two truncated forms lacking poly-Q, were studied. Full-length proteins were also expressed as C14A mutants, in order to assess whether AT-3 autoproteolytic activity was involved in its fragmentation. We found that both normal and pathological proteins localized in the cytoplasm and in the nucleus as expected, but also in the mitochondria. Microsequencing showed that all ataxins-3 underwent the same proteolytic cleavage, removing the first 27 aminoacids. Interestingly, while normal ataxins were further cleaved at a number of caspase sites, pathological AT-3 was proteolyzed to a much lesser extent. This may play a role in the pathogenesis, hampering degradation of aggregation-prone expanded AT-3. In addition, autolytic cleavage was apparently not involved in AT-3 proteolysis. (c) 2008 Elsevier Inc. All rights reserved.