Transgenic rescue of ataxia mice with neuronal-specific expression of ubiquitin-specific protease 14
Transgenic rescue of ataxia mice with neuronal-specific expression of ubiquitin-specific protease 14
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DOI：
10.1523/jneurosci.3600-06.2006
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发表时间：
2006-11-01
影响因子：
5.3
通讯作者：
Wilson, Scott M.
中科院分区：
文献类型：
--
作者：
Crimmins, Stephen;Jin, Youngam;Wilson, Scott M.
共济失调突变（ax（J））是一种隐性神经学突变，可导致小鼠生长减慢、共济失调和后肢肌肉萎缩。ax（J）基因编码泛素特异性蛋白酶14（Usp 14），一种通过其泛素样（Ubl）结构域与蛋白酶体缔合并参与加工泛素链的去泛素化酶（DUB）。对Usp 14基因产物的分析表明，Usp 14经历了选择性的前mRNA剪接，以产生能够结合蛋白酶体的全长形式的Usp 14和在Ubl结构域中含有缺失的形式。Usp 14的全长形式是ax（J）小鼠中似乎减少的唯一形式。用神经元特异性表达的Usp 14对ax（J）小鼠进行转基因拯救证明，全长形式的Usp 14足以恢复ax（J）小鼠的存活力和运动系统功能。生化分析表明，这种形式的Usp 14的泛素水解酶活性依赖于蛋白酶体的存在，全长Usp 14的神经元表达能够恢复ax（J）小鼠脑中单体泛素的水平。然而，ax（J）-拯救的小鼠仍然显示在ax（J）小鼠中观察到的浦肯野细胞轴突，表明这种小脑改变不是ax（J）运动障碍的主要原因。这些结果表明，在ax（J）小鼠中观察到的运动缺陷可归因于神经性疾病而不是肌肉疾病，并表明蛋白酶体功能的变化可能导致ax（J）小鼠的神经功能障碍。
The ataxia mutation (ax(J)) is a recessive neurological mutation that results in reduced growth, ataxia, and hindlimb muscle wasting in mice. The ax(J) gene encodes ubiquitin-specific protease 14 (Usp14), a deubiquitinating enzyme (DUB) that associates with the proteasome via its ubiquitin-like (Ubl) domain and is involved in processing ubiquitin chains. Analysis of Usp14 gene products demonstrated that Usp14 undergoes alternative pre-mRNA splicing to produce a full-length form of Usp14 that is capable of binding proteasomes and a form that contains a deletion in the Ubl domain. The full-length form of Usp14 is the only form that appears to be reduced in the ax(J) mice. Transgenic rescue of the ax(J) mice with neuronal-specific expression of Usp14 demonstrated that the full-length form of Usp14 was sufficient to restore viability and motor system function to the ax(J) mice. Biochemical analysis showed that the ubiquitin hydrolyase activity of this form of Usp14 is dependent on the presence of proteasomes, and neuronal expression of full-length Usp14 was able to restore the levels of monomeric ubiquitin in the brains of ax(J) mice. However, the ax(J)-rescued mice still displayed the Purkinje cell axonal swellings that are seen in the ax(J) mice, indicating that this cerebellar alteration is not the primary cause of the ax(J) movement disorders. These results show that the motor defects observed in the ax(J) mice are attributable to a neuropathic disease rather than to a muscular disorder and suggest that changes in proteasomal function may contribute to neurological dysfunction in the ax(J) mice.