Functional alterations of the ubiquitin-proteasome system in motor neurons of a mouse model of familial amyotrophic lateral sclerosisâ€
Functional alterations of the ubiquitin-proteasome system in motor neurons of a mouse model of familial amyotrophic lateral sclerosisâ€
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DOI：
10.1093/hmg/ddn319
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发表时间：
2009-01-01
影响因子：
3.5
通讯作者：
Bendotti, Caterina
中科院分区：
文献类型：
--
作者：
Cheroni, Cristina;Marino, Marianna;Bendotti, Caterina
在家族性和散发性肌萎缩侧索硬化症（ALS）和啮齿动物模型中，泛素-蛋白酶体系统（UPS）的改变可能是潜在有害的泛素化蛋白积累的原因，导致运动神经元死亡。在表达家族性ALS超氧化物歧化酶1（SOD 1）基因突变G93 A（SOD 1G 93 A）的转基因小鼠的脊髓中，我们发现在疾病进展过程中组成性蛋白酶体亚基减少，通过实时PCR和免疫组织化学进行评估。同时，观察到免疫蛋白酶体表达增加，这与由于胶质细胞活化引起的局部炎症反应相关。这些发现支持ALS易感组织中存在蛋白酶体修饰。为了在体内研究ALS运动神经元中UPS的功能，我们将SOD 1G 93 A小鼠与表达UPS的荧光标记的报告底物的转基因小鼠杂交。在双转基因Ub（G76 V）-GFP /SOD 1G 93 A小鼠中，在症状阶段但在症状发作之前，在少数脊髓运动神经元中可检测到指示UPS损伤的Ub（G76 V）-GFP报告基因的增加，而在反应性星形胶质细胞或小胶质细胞中不可检测到。报告基因转录物的水平没有改变，表明Ub（G76 V）-GFP的积累是由于报告基因降解缺陷所致。在一些运动神经元中，Ub（G76 V）-GFP的增加伴随着泛素和磷酸化神经丝的积累，这两种标记ALS病理学。这些数据表明，UPS损伤发生在突变SOD 1连锁ALS小鼠的运动神经元，并可能在疾病进展中发挥作用。
In familial and sporadic amyotrophic lateral sclerosis (ALS) and in rodent models of the disease, alterations in the ubiquitin-proteasome system (UPS) may be responsible for the accumulation of potentially harmful ubiquitinated proteins, leading to motor neuron death. In the spinal cord of transgenic mice expressing the familial ALS superoxide dismutase 1 (SOD1) gene mutation G93A (SOD1G93A), we found a decrease in constitutive proteasome subunits during disease progression, as assessed by real-time PCR and immunohistochemistry. In parallel, an increased immunoproteasome expression was observed, which correlated with a local inflammatory response due to glial activation. These findings support the existence of proteasome modifications in ALS vulnerable tissues. To functionally investigate the UPS in ALS motor neurons in vivo, we crossed SOD1G93A mice with transgenic mice that express a fluorescently tagged reporter substrate of the UPS. In double-transgenic Ub(G76V)-GFP /SOD1G93A mice an increase in Ub(G76V)-GFP reporter, indicative of UPS impairment, was detectable in a few spinal motor neurons and not in reactive astrocytes or microglia, at symptomatic stage but not before symptoms onset. The levels of reporter transcript were unaltered, suggesting that the accumulation of Ub(G76V)-GFP was due to deficient reporter degradation. In some motor neurons the increase of Ub(G76V)-GFP was accompanied by the accumulation of ubiquitin and phosphorylated neurofilaments, both markers of ALS pathology. These data suggest that UPS impairment occurs in motor neurons of mutant SOD1-linked ALS mice and may play a role in the disease progression.