Proteolysis of Mutant Huntingtin Produces an Exon 1 Fragment That Accumulates as an Aggregated Protein in Neuronal Nuclei in Huntington Disease
Proteolysis of Mutant Huntingtin Produces an Exon 1 Fragment That Accumulates as an Aggregated Protein in Neuronal Nuclei in Huntington Disease
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DOI：
10.1074/jbc.m109.075028
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发表时间：
2010-03-19
影响因子：
4.8
通讯作者：
Bates, Gillian P.
中科院分区：
文献类型：
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作者：
Landles, Christian;Sathasivam, Kirupa;Bates, Gillian P.
亨廷顿蛋白水解与亨廷顿病 (HD) 的分子发病机制有关。尽管付出了巨大的努力，致病性最小 N 端片段的身份仍未确定。使用一组抗亨廷顿蛋白抗体，我们采用公正的方法在 HD 的 HdhQ150 敲入小鼠模型中生成突变型和野生型亨廷顿蛋白的蛋白水解裂解图谱。我们鉴定了 14 个显着的 N 末端片段，除了全长蛋白质之外，还可以在细胞质片段中轻松检测到这些片段，但在细胞核片段中却无法检测到这些片段。这些碎片在所有年龄段都被检测到，并不是致病过程的结果。我们证明了最小的片段是外显子 1 亨廷顿蛋白，已知其含有有效的核输出信号。在行为表型出现之前，外显子 1 蛋白和可能的其他小片段以去污剂不溶性复合物的形式积聚在神经元细胞核中，在组织切片中表现为弥漫性颗粒核染色。该方法可用于通过药理学或遗传学方法验证特定蛋白酶的抑制作用作为 HD 的治疗靶点。
Huntingtin proteolysis has been implicated in the molecular pathogenesis of Huntington disease (HD). Despite an intense effort, the identity of the pathogenic smallest N-terminal fragment has not been determined. Using a panel of anti-huntingtin antibodies, we employed an unbiased approach to generate proteolytic cleavage maps of mutant and wild-type huntingtin in the HdhQ150 knock-in mouse model of HD. We identified 14 prominent N-terminal fragments, which, in addition to the full-length protein, can be readily detected in cytoplasmic but not nuclear fractions. These fragments were detected at all ages and are not a consequence of the pathogenic process. We demonstrated that the smallest fragment is an exon 1 huntingtin protein, known to contain a potent nuclear export signal. Prior to the onset of behavioral phenotypes, the exon 1 protein, and possibly other small fragments, accumulate in neuronal nuclei in the form of a detergent insoluble complex, visualized as diffuse granular nuclear staining in tissue sections. This methodology can be used to validate the inhibition of specific proteases as therapeutic targets for HD by pharmacological or genetic approaches.