Mutant torsinA, responsible for early-onset torsion dystonia, forms membrane inclusions in cultured neural cells
Mutant torsinA, responsible for early-onset torsion dystonia, forms membrane inclusions in cultured neural cells
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DOI：
10.1093/hmg/9.9.1403
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发表时间：
2000-05-22
影响因子：
3.5
通讯作者：
Breakefield, XO
中科院分区：
文献类型：
--
作者：
Hewett, J;Gonzalez-Agosti, C;Breakefield, XO
早发性扭转肌张力障碍是一种遗传性运动障碍，被认为是由于基底神经节多巴胺释放减少引起的，没有明显的神经元变性。最近克隆的基因负责这种疾病，TOR 1A（DYT 1），确定了编码的蛋白质，torsinA，作为AAA+伴侣蛋白超家族的成员，并揭示了最高水平的表达在多巴胺能神经元在人脑。这种疾病的大多数病例是由蛋白质C-末端区域的一个谷氨酸残基缺失引起的。针对torsinA产生的抗体揭示了通过蛋白质印迹分析在神经、神经胶质和成纤维细胞系中与预测的37.8 kDa大小相似的主要免疫反应性蛋白质种类的表达。该蛋白质是N-糖基化的，具有高甘露糖含量，并且显然没有磷酸化。过表达torsinA在小鼠神经CAD细胞免疫细胞化学，揭示了一个显着不同的分布模式的野生型和突变形式的蛋白质。野生型蛋白质被发现在整个细胞质和神经突与内质网（ER）标记，蛋白质二硫键异构酶的高度共定位。与此相反，突变蛋白质积累在多个，大的包涵体在细胞核周围的细胞质。这些内含物由膜涡组成，显然来自ER。如果突变蛋白的破坏加工导致其在体内多层膜结构中的积累，则这些可能干扰神经元中的膜运输。
Early-onset torsion dystonia is a hereditary movement disorder thought to be caused by decreased release of dopamine into the basal ganglia, without apparent neuronal degeneration. Recent cloning of the gene responsible for this disease, TOR1 A (DYT1), identified the encoded protein, torsinA, as a member of the AAA+ superfamily of chaperone proteins and revealed highest levels of expression in dopaminergic neurons in human brain. Most cases of this disease are caused by a deletion of one glutamic acid residue in the C-terminal region of the protein. Antibodies generated against torsinA revealed expression of a predominant immunoreactive protein species similar to the predicted size of 37.8 kDa in neural, glial and fibroblastic lines by western blot analysis. This protein is N-glycosylated with high mannose content and not, apparently, phosphorylated. Overexpression of torsinA in mouse neural CAD cells followed by immunocytochemistry, revealed a dramatically different pattern of distribution for wild-type and mutant forms of the protein. The wild-type protein was found throughout the cytoplasm and neurites with a high degree of co-localization with the endoplasmic reticulum (ER) marker, protein disulfide isomerase. In contrast, the mutant protein accumulated in multiple, large inclusions in the cytoplasm around the nucleus. These inclusions were composed of membrane whorls, apparently derived from the ER. If disrupted processing of the mutant protein leads to its accumulation in multilayer membranous structures in vivo, these may interfere with membrane trafficking in neurons.