Identification of Caspase-6-mediated processing of the valosin containing protein (p97) in Alzheimer's disease: a novel link to dysfunction in ubiquitin proteasome system-mediated protein degradation.
Identification of Caspase-6-mediated processing of the valosin containing protein (p97) in Alzheimer's disease: a novel link to dysfunction in ubiquitin proteasome system-mediated protein degradation.
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鉴定caspase-6介导的含有蛋白质蛋白（p97）的加工在阿尔茨海默氏病中：与泛素蛋白酶系统系统介导的蛋白质降解的功能障碍的新型联系。
DOI：
10.1523/jneurosci.5874-09.2010
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发表时间：
2010-04-28
期刊：
影响因子：
--
通讯作者：
LeBlanc AC
中科院分区：
文献类型：
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作者：
Halawani D;Tessier S;Anzellotti D;Bennett DA;Latterich M;LeBlanc AC
valosin-containing蛋白（p97）是一种泛素依赖的ATP酶，在泛素蛋白酶体系统（UPS）介导的蛋白质降解途径中起着重要作用。p97最近被鉴定为原代人神经元中活性Caspase-6（Casp 6）的假定底物。由于Casp 6在轻度认知障碍（MCI）和阿尔茨海默病（AD）患者的大脑中被激活，因此Casp 6靶向p97可能是导致AD中UPS受损的重要步骤。在这里，我们表明，p97是在体外和体内的Casp 6底物。重组p97的Casp 6切割产生了28和20 kDa的两个N-末端片段，这两个片段不是由其他两种效应物半胱天冬酶Caspase-3和Caspase-7产生的。ATP结合到p97的D1 ATP酶环降低了N-结构域对半胱天冬酶介导的蛋白水解的敏感性。质谱分析鉴定VAPD 179为p97的N-结构域内的Casp 6切割位点。抗新表位血清免疫化学检测到MCI和AD中海马神经元的细胞索马和神经突的细胞质中在VAPD 179处切割的p97。p97（1-179）片段的过表达，代表p97在D179处裂解，损害了泛素融合降解和N端规则途径中的模型底物的降解，并使内源性p97不稳定。总的来说，这些结果表明，在AD中，p97被Casp 6裂解，并表明p97裂解是UPS损伤的重要机制。
The valosin-containing protein (p97) is a ubiquitin-dependent ATPase that plays central roles in ubiquitin proteasome system (UPS)-mediated protein degradation pathways. p97 has been recently identified as a putative substrate of active Caspase-6 (Casp6) in primary human neurons. Since Casp6 is activated in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) patients’ brains, the targeting of p97 by Casp6 may represent an important step that leads to UPS impairment in AD. Here, we show that p97 is a Casp6 substrate in vitro and in vivo. Casp6 cleavage of recombinant p97 generated two N-terminal fragments of 28 and 20 kDa, which were not generated by the other two effector caspases, Caspase-3 and Caspase-7. ATP binding to the D1 ATPase ring of p97 reduced the susceptibility of the N-domain to caspase-mediated proteolysis. Mass spectrometric analysis identified VAPD179 as a Casp6 cleavage site within p97’s N-domain. An anti-neoepitope serum immunohistochemically detected p97 cleaved at VAPD179 in the cytoplasm of the cell soma and neurites of hippocampal neurons in MCI and AD. Overexpression of p97 (1-179) fragment, representing p97 cleaved at D179, impaired the degradation of model substrates in the ubiquitin-fusion degradation and the N-end rule pathways, and destabilized endogenous p97. Collectively, these results show that p97 is cleaved by Casp6 in AD and suggest p97 cleavage as an important mechanism for UPS impairment.