Increased expression of p62 in expanded polyglutamine-expressing cells and its association with polyglutamine inclusions
Increased expression of p62 in expanded polyglutamine-expressing cells and its association with polyglutamine inclusions
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DOI：
10.1111/j.1471-4159.2004.02692.x
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发表时间：
2004-10-01
影响因子：
4.7
通讯作者：
Nukina, N
中科院分区：
文献类型：
--
作者：
Nagaoka, U;Kim, K;Nukina, N
亨廷顿病是一种进行性神经退行性疾病，与编码亨廷顿蛋白的基因中的CAG重复扩增有关。我们发现，60 kDa的蛋白质增加Neuro 2a细胞表达的N-末端部分的亨廷顿蛋白与扩大聚谷氨酰胺。我们纯化了这种蛋白质，并使用质谱法将其鉴定为p62，一种含有泛素相关结构域的蛋白质。一种特异性p62抗体染色的泛素化polyQ包涵体在扩大聚谷氨酰胺表达细胞，以及在大脑中的亨廷顿蛋白外显子1转基因小鼠。此外，p62蛋白和mRNA的水平增加，在扩大聚谷氨酰胺表达细胞。我们还发现，p62形成侵略样包涵体时，p62蛋白酶体抑制剂在正常Neuro 2a细胞增加。p62的敲低不影响侵袭体或多聚谷氨酰胺包涵体的形成，表明p62被募集到侵袭体或继发于其形成的包涵体。这些结果表明，p62可能发挥重要作用，作为一个响应蛋白的聚谷氨酰胺诱导的压力，而不是作为一个泛素化蛋白之间的交联剂。
Huntington's disease is a progressive neurodegenerative disorder that is associated with a CAG repeat expansion in the gene encoding huntingtin. We found that a 60-kDa protein was increased in Neuro2a cells expressing the N-terminal portion of huntingtin with expanded polyglutamine. We purified this protein, and, using mass spectrometry, identified it as p62, an ubiquitin-associated domain-containing protein. A specific p62 antibody stained the ubiquitylated polyQ inclusions in expanded polyglutamine-expressing cells, as well as in the brain of the huntingtin exon 1 transgenic mice. Furthermore, the level of p62 protein and mRNA was increased in expanded polyglutamine-expressing cells. We also found that p62 formed aggresome-like inclusions when p62 was increased in normal Neuro2a cells by a proteasome inhibitor. Knock-down of p62 does not affect the formation of aggresomes or polyglutamine inclusions, suggesting that p62 is recruited to the aggresome or inclusions secondary to their formation. These results suggest that p62 may play important roles as a responsive protein to a polyglutamine-induced stress rather than as a cross-linker between ubiquitylated proteins.