Production of sporadic ALS model mice by targeting the ADAR2 gene in motor neurons

我们最近证明，GluR2 （AMPA受体的一个亚基）的Q/R位点rna编辑在散发性而非家族性ALS患者的运动神经元中以疾病特异性和神经元类别选择性的方式显着减少。GluR2 Q / R。位点编辑是由作用于RNA 2型（ADAR2）的腺苷脱氨酶特异性催化的，由于该位点的RNA编辑显著减少，全体性ADAR2缺失的小鼠年轻时死于癫痫持续状态。这种酶活性的降低可能是在散发性ALS运动神经元中观察到GluR2 Q/R位点编辑不足和神经元死亡的原因。为了研究ADAR2缺陷是否是散发性ALS中运动神经元缓慢死亡的原因，我们利用Cre-loxP系统选择性地敲除运动神经元中的ADAR2基因，并对小鼠进行了基因修饰。我们研究了与对照组小鼠相比，这些小鼠的运动功能、存活时间和adar2缺陷神经元的神经元损失的变化。这些突变小鼠的平均生存期明显短于对照组小鼠，并且以Cre表达依赖的方式表现出进行性运动选择性行为缺陷。缺乏ADAR2的运动神经元经历缓慢的进行性死亡，而表达ADAR2的运动神经元在小鼠一生中保持完整。在死亡的adar2缺陷运动神经元中，GluR2 Q/R位点的RNA编辑完全丢失。在ADAR2基因敲除小鼠中，我们证明ADAR2基因缺失可诱导GluR2 Q/R位点编辑不足，导致运动神经元缓慢进行性死亡。目前的结果可能表明，ADAR2活性不足可能是散发性ALS中神经元死亡的一个原因。该突变小鼠模型可用于散发性ALS的研究。

We recently demonstrated that Q/R site-RNA editing of GluR2, a subunit of AMPA receptors, is markedly decreased in motor neurons of sporadic, but not familial, ALS patients in a disease-specific and neuronal class-selective manner. GluR2 Q/R. site-editing is specifically catalyzed by adenosine deaminase acting on RNA type 2 (ADAR2) and systemic ADAR2-null mice die young from status epilepticus due to a marked reduction in RNA editing at this site. Reduction of this enzyme activity is likely the cause of GluR2 Q/R site-underediting and neuronal death observed in sporadic ALS motor neurons.To investigate whether deficient ADAR2 is a cause of slow death of motor neurons as seen in sporadic ALS, we developed genetically modified mice in that the ADAR2 gene is selectively knocked out in motor neurons using Cre-loxP system. We investigated the changes in motor function, survival length, neuronal loss of ADAR2-deficient neurons in these mice as compared to control mice.These mutant mice displayed significantly shorter mean survival than control mice and progressive motor-selective behavioral deficit in a Cre expression-dependent manner. Motor neurons deficient for ADAR2 underwent slowly progressive death, whereas ADAR2-expressing motor neurons remains intact during the mouse life. RNA editing at the GluR2 Q/R site was completely lost in dying, ADAR2-deficient motor neurons.Here we demonstrated that loss of ADAR2 induces GluR2 Q/R site-underediting with resultant slowly progressive death of motor neurons in the ADAR2 knockout mice. Present results likely indicate that ADAR2 under-activity may be a cause of neuronal death in sporadic ALS. This mutant mouse model would be useful in research into sporadic ALS.