Generation of novel animal models for amyofrophic lateral sclerosis and studies on the molecular mechanisms underlying motor dysfunction

ALS2的功能突变缺失导致了许多青少年/婴儿隐性运动神经元疾病，这表明其基因产物ALS2在神经元亚群的维持和存活中起着至关重要的作用。然而，ALS2在体内的正常生理作用和运动功能障碍的分子机制尚不清楚。为了解决这些问题，我们在本研究中培育了几系ALS2转基因小鼠和ALS2敲除（KO）小鼠的基因系。在小鼠中，ALS2的缺失和过表达都不会单独产生严重的疾病表型。然而，当将Als2-KO小鼠与表达als连锁SOD1H46R Als2-KO的SOD1R46R小鼠系杂交时；SOD1^<H46R>小鼠比SODIH46R小鼠表现出更早的运动功能障碍和更短的寿命，这表明ALS2在体内与SOD1突变体相关的运动神经元疾病的发生和/或进展中起作用。接下来，为了阐明神经元的ALS2功能，我们进一步研究了ALS2缺陷原代培养神经元的细胞表型。ALS2缺乏不仅会导致海马神经元轴突生长延迟，还会导致皮质神经元巨噬细胞活动水平降低，提示ALS2通过调节膜动力学在神经元分化和/或发育中起调节作用。最后，我们研究了一个新的ALS2同源物ALS2CL的分子特征及其与ALS2的功能关系。结果表明，ALS2CL是一种新的als2相互作用蛋白，参与了als2介导的内体动力学。总之，我们新生成的过表达和/或删除ALS2的动物应该提供宝贵的研究工具，以了解ALS2介导的内体动力学与体内运动神经元的长期活力之间的相互作用。对这些小鼠的进一步表征也将阐明als2介导的神经元功能在突变sod1相关als发病机制中的意义。少

Loss of function mutations in ALS2 account for a number of juvenile/infantile recessive motor neuron diseases, indicating that its gene product, ALS2, plays a crucial role in maintenance and survival for a subset of neurons. However, the normal physiological role of ALS2 in vivo and the molecular mechanisms underlying motor dysfunction are still unknown. To address these issues, we generated several lines of ALS2 transgenic mice and congenic lines of the Als2 knock-out (KO) mice in this study. Neither loss nor overexpression of ALS2 solely produced a severe disease phenotype in mice. However, when the Als2-KO mice was crossed with the SOD1R46R mouse line expressing familial ALS-linked SOD1H46R Als2-KO ; SOD1^<H46R>mice showed a much earlier motor dysfunction as well as a shorter life span than SODIH46R mice, suggesting that ALS2 plays a role in the onset and/or progression of motor neuron disease associated with mutant SOD1 in vivo. Next, to elucidate the neuronal ALS2 functions, we in … More vestigated cellular phenotypes of ALS2-deficient primary cultured neurons. ALS2 deficiency resulted not only in the delay of axon outgrowth in hippocampal neurons, but also in a decreased level of the macropinocytic activity in cortical neurons, suggesting that ALS2 acts as a modulator in neuronal differentiation and/or development through regulation of membrane dynamics. Finally, we investigated the molecular features of ALS2CL, a novel ALS2 homolog, and its functional relationship with ALS2. It was revealed that ALS2CL was a novel ALS2-interacting protein and was implicated in ALS2-mediated endosome dynamics. Collectively, our newly generated animals overexpressing and/or deleting ALS2 should provide invaluable research tools with which to understand the interplay between ALS2-mediated endosomal dynamics and the long-term viability of motor neurons in vivo. Further characterization of these mice will also clarify the implication of the ALS2-mediated neuronal functions in the pathogenesis for mutant SOD1-linkedALS. Less