Cooper J K, Schilling G, Peters M F, Herring W J, Sharp A H, Kaminsky Z, Masone J, Khan F A, Delanoy M, Borchelt D R, Dawson V L, Dawson T M, Ross C A
Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196, USA.
Hum Mol Genet. 1998 May;7(5):783-90. doi: 10.1093/hmg/7.5.783.
Huntington's disease (HD) is a progressive neurodegenerative disorder caused by an expanding CAG repeat coding for polyglutamine in the huntingtin protein. Recent data have suggested the possibility that an N-terminal fragment of huntingtin may aggregate in neurons of patients with HD, both in the cytoplasm, forming dystrophic neurites, and in the nucleus, forming intranuclear neuronal inclusion bodies. An animal model of HD using the short N-terminal fragment of huntingtin has also been found to have intranuclear inclusions and this same fragment can aggregate in vitro . We have now developed a cell culture model demonstrating that N-terminal fragments of huntingtin with expanded glutamine repeats aggregate both in the cytoplasm and in the nucleus. Neuroblastoma cells transiently transfected with full-length huntingtin constructs with either a normal or expanded repeat had diffuse cytoplasmic localization of the protein. In contrast, cells transfected with truncated N-terminal fragments showed aggregation only if the glutamine repeat was expanded. The aggregates were often ubiquitinated. The shorter truncated product appeared to form more aggregates in the nucleus. Cells transfected with the expanded repeat construct but not the normal repeat construct showed enhanced toxicity to the apoptosis-inducing agent staurosporine. These data indicate that N-terminal truncated fragments of huntingtin with expanded glutamine repeats can aggregate in cells in culture and that this aggregation can be toxic to cells. This model will be useful for future experiments to test mechanisms of aggregation and toxicity and potentially for testing experimental therapeutic interventions.
亨廷顿舞蹈症（HD）是一种进行性神经退行性疾病，由亨廷顿蛋白中编码多聚谷氨酰胺的CAG重复序列扩增引起。最近的数据表明，亨廷顿蛋白的N端片段可能在HD患者的神经元中聚集，在细胞质中形成营养不良性神经突，在细胞核中形成核内神经元包涵体。使用亨廷顿蛋白短N端片段的HD动物模型也被发现有核内包涵体，并且相同的片段在体外也能聚集。我们现在建立了一个细胞培养模型，证明谷氨酰胺重复序列扩增的亨廷顿蛋白N端片段在细胞质和细胞核中均会聚集。用正常或扩增重复序列的全长亨廷顿构建体瞬时转染的神经母细胞瘤细胞中，该蛋白呈弥漫性细胞质定位。相比之下，转染截短N端片段的细胞只有在谷氨酰胺重复序列扩增时才会出现聚集。这些聚集体常常被泛素化。较短的截短产物似乎在细胞核中形成更多聚集体。转染扩增重复序列构建体而非正常重复序列构建体的细胞对凋亡诱导剂星形孢菌素表现出增强的毒性。这些数据表明，谷氨酰胺重复序列扩增的亨廷顿蛋白N端截短片段可在培养细胞中聚集，且这种聚集对细胞有毒性。该模型将有助于未来测试聚集和毒性机制的实验，也可能有助于测试实验性治疗干预措施。
