The ubiquitin C-terminal hydrolase L1 (UCH-L1) C terminus plays a key role in protein stability, but its farnesylation is not required for membrane association in primary neurons.
The ubiquitin C-terminal hydrolase L1 (UCH-L1) C terminus plays a key role in protein stability, but its farnesylation is not required for membrane association in primary neurons.
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DOI：
10.1074/jbc.m114.557124
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发表时间：
2014-12-26
期刊：
影响因子：
--
通讯作者：
Henley JM
中科院分区：
文献类型：
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作者：
Bishop P;Rubin P;Thomson AR;Rocca D;Henley JM
背景：膜相关UCH-L1已被认为是治疗神经退行性变的靶点。结果：UCH-L1与神经细胞膜的结合不涉及法尼化。C末端截断会导致蛋白质错误折叠和神经元死亡。结论：UCH-L1的C末端调节蛋白质的聚集和稳定性。意义：CTTΔ4突变体为研究神经毒性Uch-L1聚集事件提供了一个模型。泛素C末端水解酶L1(UCH-L1)是一种在神经元中高表达的脱泛素化酶。UCH-L1在神经退行性变中的可能作用已经被强调，因为它存在于与帕金森病相关的路易小体和阿尔茨海默病中观察到的神经原纤维缠结。UCH-L1在神经元中以两种形式存在，即可溶性胞浆形式(UCH-L1C)和膜结合形式(UCH-L1M)。阿尔茨海默病患者的大脑显示出与Uch-L1免疫反应tau缠结的形成相关的可溶性Uch-L1C水平降低，而Uch-L1M与α-突触核蛋白功能障碍有关。鉴于这些不同角色的报道，我们研究了UCH-L1膜缔合的性质。令人惊讶的是，我们的结果表明，在我们测试的培养细胞系中，UCH-L1不能分割到膜上。此外，在原代培养的神经元中，一定比例的UCH-L1M确实分配到膜上，但与先前的报告相反，这不需要法尼化。四个C末端残基的缺失导致蛋白质的溶解性丧失，底物结合消失，细胞死亡增加，细胞内分布异常，与蛋白质功能障碍和聚集一致。这些数据表明，与克隆细胞系相比，UCH-L1在神经元中的处理方式不同，法尼化不能解释神经元中的膜结合。
Background: Membrane-associated UCH-L1 has been proposed as a target for treating neurodegeneration. Results: UCH-L1 association with neuronal membranes does not involve farnesylation. C-terminal truncation causes protein misfolding and neuronal death. Conclusion: The C terminus of UCH-L1 regulates protein aggregation and stability. Significance: The CTTΔ4 mutant provides a model for studying neurotoxic UCH-L1 aggregation events. Ubiquitin C-terminal hydrolase L1 (UCH-L1) is a deubiquitinating enzyme that is highly expressed in neurons. A possible role for UCH-L1 in neurodegeneration has been highlighted because of its presence in Lewy bodies associated with Parkinson disease and neurofibrillary tangles observed in Alzheimer disease. UCH-L1 exists in two forms in neurons, a soluble cytoplasmic form (UCH-L1C) and a membrane-associated form (UCH-L1M). Alzheimer brains show reduced levels of soluble UCH-L1C correlating with the formation of UCH-L1-immunoreactive tau tangles, whereas UCH-L1M has been implicated in α-synuclein dysfunction. Given these reports of divergent roles, we investigated the properties of UCH-L1 membrane association. Surprisingly, our results indicate that UCH-L1 does not partition to the membrane in the cultured cell lines we tested. Furthermore, in primary cultured neurons, a proportion of UCH-L1M does partition to the membrane, but, contrary to a previous report, this does not require farnesylation. Deletion of the four C-terminal residues caused the loss of protein solubility, abrogation of substrate binding, increased cell death, and an abnormal intracellular distribution, consistent with protein dysfunction and aggregation. These data indicate that UCH-L1 is differently processed in neurons compared with clonal cell lines and that farnesylation does not account for the membrane association in neurons.