The ataxia protein sacsin is a functional co-chaperone that protects against polyglutamine-expanded ataxin-1.
The ataxia protein sacsin is a functional co-chaperone that protects against polyglutamine-expanded ataxin-1.
复制标题
DOI：
10.1093/hmg/ddp067
复制
发表时间：
2009-05-01
影响因子：
3.5
通讯作者：
Chapple JP
中科院分区：
文献类型：
--
作者：
Parfitt DA;Michael GJ;Vermeulen EG;Prodromou NV;Webb TR;Gallo JM;Cheetham ME;Nicoll WS;Blatch GL;Chapple JP
一个广泛的蛋白质相互作用网络已被确定在涉及遗传性共济失调的蛋白质之间。在早发性神经退行性疾病常染色体隐性痉挛性共济失调中发生突变的蛋白sacsin是这个相互作用组的一个节点。在这里，我们已经建立了sacsin的神经元表达和4579氨基酸蛋白的功能特征域。在大神经元中，尤其是在脑运动系统中，包括小脑浦肯野细胞，Sacsin的表达量最高。它在SH-SY5Y神经母细胞瘤细胞中的亚细胞定位主要是细胞质，具有线粒体成分。我们在sacsin的n端发现了一个假定的泛素样（UbL）结构域，并证明了它与蛋白酶体的相互作用。此外，sacsin含有一个预测的j结构域，这是DnaJ/Hsp40蛋白的定义特征。利用细菌互补实验，sacsin j结构域被证明是功能性的。在sacsin中同时存在UbL和j结构域，表明它可能整合泛素-蛋白酶体系统和Hsp70功能以发挥特定的细胞作用。Hsp70伴侣机制是细胞对与神经退行性疾病相关的易聚集突变蛋白反应的重要组成部分。因此，我们研究了sirna介导的sacsin敲低对聚谷氨酰胺扩增ataxin-1的影响。重要的是，SACS siRNA不影响GFP-ataxin-1的细胞活力[30Q]，但增强了GFP-ataxin-1的毒性[82Q]，表明sacsin对突变的ataxin-1具有保护作用。因此，sacsin是一种共济失调蛋白和Hsp70伴侣机制的调节剂，该机制与其他共济失调相关蛋白的加工有关。
An extensive protein–protein interaction network has been identified between proteins implicated in inherited ataxias. The protein sacsin, which is mutated in the early-onset neurodegenerative disease autosomal recessive spastic ataxia of Charlevoix-Saguenay, is a node in this interactome. Here, we have established the neuronal expression of sacsin and functionally characterized domains of the 4579 amino acid protein. Sacsin is most highly expressed in large neurons, particularly within brain motor systems, including cerebellar Purkinje cells. Its subcellular localization in SH-SY5Y neuroblastoma cells was predominantly cytoplasmic with a mitochondrial component. We identified a putative ubiquitin-like (UbL) domain at the N-terminus of sacsin and demonstrated an interaction with the proteasome. Furthermore, sacsin contains a predicted J-domain, the defining feature of DnaJ/Hsp40 proteins. Using a bacterial complementation assay, the sacsin J-domain was demonstrated to be functional. The presence of both UbL and J-domains in sacsin suggests that it may integrate the ubiquitin–proteasome system and Hsp70 function to a specific cellular role. The Hsp70 chaperone machinery is an important component of the cellular response towards aggregation prone mutant proteins that are associated with neurodegenerative diseases. We therefore investigated the effects of siRNA-mediated sacsin knockdown on polyglutamine-expanded ataxin-1. Importantly, SACS siRNA did not affect cell viability with GFP-ataxin-1[30Q], but enhanced the toxicity of GFP-ataxin-1[82Q], suggesting that sacsin is protective against mutant ataxin-1. Thus, sacsin is an ataxia protein and a regulator of the Hsp70 chaperone machinery that is implicated in the processing of other ataxia-linked proteins.
登录
查看更多内容
影响因子：
4
作者：
Breedveld, GJ;van Wetten, B;Maat-Kievit, JA
通讯作者：
Maat-Kievit, JA
影响因子：
3.7
作者：
Rich, Tina;Varadaraj, Archana
通讯作者：
Varadaraj, Archana
影响因子：
21.3
作者：
Connell, P;Ballinger, CA;Patterson, C
通讯作者：
Patterson, C
DOI：
10.1016/j.biocel.2006.11.006
发表时间：
2007-01-01
影响因子：
4
作者：
Nicoll, W. S.;Botha, M.;Blatch, G. L.
通讯作者：
Blatch, G. L.
影响因子：
13.8
作者：
Upadhya, SC;Hegde, AN
通讯作者：
Hegde, AN