Proteasomal-dependent aggregate reversal and absence of cell death in a conditional mouse model of Huntington's disease
Proteasomal-dependent aggregate reversal and absence of cell death in a conditional mouse model of Huntington's disease
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DOI：
10.1523/jneurosci.21-22-08772.2001
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发表时间：
2001-11-15
影响因子：
5.3
通讯作者：
Lucas, JJ
中科院分区：
文献类型：
--
作者：
Martín-Aparicio, E;Yamamoto, A;Lucas, JJ
神经元核内包涵体是亨廷顿氏病的组织病理学标志。然而，它们形成的确切机制以及它们与神经元细胞死亡和/或功能障碍的相关性仍不清楚。我们最近建立了亨廷顿氏病的条件小鼠模型（HD94），其中沉默突变亨廷顿蛋白的表达导致核内聚集体的消失和行为表型的改善。在这里，我们分析了HD94小鼠的原代纹状体神经元培养，以探索聚集形成和逆转的动力学，可能涉及的机制，以及聚集与神经元死亡之间的关系。与此同时，我们在类似的研究中研究了有症状的成年HD94小鼠，并探索了聚集清除率与行为逆转之间的关系。我们报道，在培养中，聚集体的形成和逆转是一个快速的过程，如转基因表达2天导致聚集体形成，转基因抑制5天导致聚集体消失。在小鼠中，聚集体和核内突变亨廷顿蛋白的完全逆转比之前报道的要快，并且在运动恢复之前几周。此外，蛋白酶体抑制剂lactacystin抑制了在培养中观察到的聚集体清除，从而表明聚集体的形成是亨廷顿蛋白合成速率与蛋白酶体降解速率之间的平衡。最后，突变huntingtin的表达和聚集体都没有损害HD94培养的生存能力。这与有症状的HD94小鼠缺乏细胞死亡相关，从而表明由突变亨廷顿蛋白引发的神经元功能障碍，而不是细胞损失，是症状学的基础。
Neuronal intranuclear inclusions are a histopathological hallmark of Huntington's disease. Nevertheless, the precise mechanism by which they are formed and their relevance to neuronal cell death and/or dysfunction remains unclear. We recently generated a conditional mouse model of Huntington's disease (HD94) in which silencing expression of mutated huntingtin led to the disappearance of intranuclear aggregates and amelioration of the behavioral phenotype. Here, we analyze primary striatal neuronal cultures from HD94 mice to explore the dynamics of aggregate formation and reversal, the possible mechanisms involved, and the correlation between aggregates and neuronal death. In parallel, we examine symptomatic adult HD94 mice in similar studies and explored the relationship between aggregate clearance and behavioral reversal. We report that, in culture, aggregate formation and reversal were rapid processes, such that 2 d of transgene expression led to aggregate formation, and 5 d of transgene suppression led to aggregate disappearance. In mice, full reversal of aggregates and intranuclear mutant huntingtin was more rapid than reported previously and preceded the motor recovery by several weeks. Furthermore, the proteasome inhibitor lactacystin inhibited the aggregate clearance observed in culture, thus indicating that aggregate formation is a balance between the rate of huntingtin synthesis and its degradation by the proteasome. Finally, neither expression of the mutant huntingtin nor aggregates compromised the viability of HD94 cultures. This correlated with the lack of cell death in symptomatic HD94 mice, thus demonstrating that neuronal dysfunction, and not cell loss, triggered by mutant huntingtin underlies symptomatology.