Loss of Clcc1 Results in ER Stress, Misfolded Protein Accumulation, and Neurodegeneration
Loss of Clcc1 Results in ER Stress, Misfolded Protein Accumulation, and Neurodegeneration
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DOI：
10.1523/jneurosci.3678-14.2015
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发表时间：
2015-02-18
影响因子：
5.3
通讯作者：
Ackerman, Susan L.
中科院分区：
文献类型：
--
作者：
Jia, Yichang;Jucius, Thomas J.;Ackerman, Susan L.
跨膜蛋白和分泌蛋白的折叠在转运至细胞表面之前发生在内质网（ER）的内腔中，并且由未折叠蛋白反应（UPR）信号传导途径监测。ER中未折叠蛋白的积累激活UPR，UPR通过调节基因表达恢复ER稳态，导致ER蛋白折叠能力增加和ER蛋白折叠负荷减少。然而，延长的UPR活性与多种病理条件下的细胞死亡有关，包括神经变性。在这里，我们报告了一个自发的隐性小鼠突变，导致进行性小脑颗粒细胞死亡和外周运动轴突变性。通过定位克隆，我们确定在这个菌株中的突变作为一个反转录转座子插入Clcc 1基因，它编码一个假定的氯离子通道本地化的ER。此外，我们表明，C3 H/HeSnJ近交系有迟发性小脑变性，由于这种突变。有趣的是，培养细胞中Clcc 1表达的急性敲低增加了对ER应激的敏感性。在协议中，GRP 78，在ER中的主要HSP 70家族伴侣，在体内Clcc 1缺陷的颗粒细胞中上调，并且泛素化蛋白在这些神经元变性前积累。这些数据表明，ER中氯稳态的破坏破坏了ER的蛋白质折叠能力，导致最终的神经元死亡。
Folding of transmembrane and secretory proteins occurs in the lumen of the endoplasmic reticulum (ER) before transportation to the cell surface and is monitored by the unfolded protein response (UPR) signaling pathway. The accumulation of unfolded proteins in the ER activates the UPR that restores ER homeostasis by regulating gene expression that leads to an increase in the protein-folding capacity of the ER and a decrease in the ER protein-folding load. However, prolonged UPR activity has been associated with cell death in multiple pathological conditions, including neurodegeneration. Here, we report a spontaneous recessive mouse mutation that causes progressive cerebellar granule cell death and peripheral motor axon degeneration. By positional cloning, we identify the mutation in this strain as a retrotransposon insertion in the Clcc1 gene, which encodes a putative chloride channel localized to the ER. Furthermore, we demonstrate that the C3H/HeSnJ inbred strain has late onset cerebellar degeneration due to this mutation. Interestingly, acute knockdown of Clcc1 expression in cultured cells increases sensitivity to ER stress. In agreement, GRP78, the major HSP70 family chaperone in the ER, is upregulated in Clcc1-deficient granule cells in vivo, and ubiquitinated proteins accumulate in these neurons before their degeneration. These data suggest that disruption of chloride homeostasis in the ER disrupts the protein-folding capacity of the ER, leading to eventual neuron death.