Mutations in the AAA+ ATPase cause multisystem proteinopathy 1, which includes amyotrophic lateral sclerosis; however, the pathogenic mechanisms that contribute to motor neuron loss remain obscure. Here, we use two induced pluripotent stem cell models differentiated into spinal motor neurons to investigate how mutations perturb the motor neuron proteome. Using quantitative proteomics, we find that motor neurons harboring the R155H mutation have deficits in the selective autophagy of lysosomes (lysophagy). R155H motor neurons are unable to clear damaged lysosomes and have reduced viability. Lysosomes in mutant motor neurons have increased pH compared with wild-type cells. The clearance of damaged lysosomes involves UBXD1-p97 interaction, which is disrupted in mutant motor neurons. Finally, inhibition of the ATPase activity of p97 using the inhibitor CB-5083 rescues lysophagy defects in mutant motor neurons. These results add to the evidence that endo-lysosomal dysfunction is a key aspect of disease pathogenesis in p97-related disorders.

中文翻译：

---

ALS 相关 p97 R155H 突变破坏 iPSC 衍生运动神经元的溶食作用

AAA+ ATP酶突变导致多系统蛋白病1，其中包括肌萎缩侧索硬化症；然而，导致运动神经元损失的致病机制仍然不清楚。在这里，我们使用两种分化为脊髓运动神经元的诱导多能干细胞模型来研究突变如何扰乱运动神经元蛋白质组。使用定量蛋白质组学，我们发现携带 R155H 突变的运动神经元在溶酶体的选择性自噬（溶食）方面存在缺陷。R155H 运动神经元无法清除受损的溶酶体，活力降低。与野生型细胞相比，突变型运动神经元中的溶酶体的 pH 值升高。受损溶酶体的清除涉及 UBXD1-p97 相互作用，这种相互作用在突变运动神经元中被破坏。最后，使用抑制剂 CB-5083 抑制 p97 的 ATP 酶活性可挽救突变运动神经元的溶食缺陷。这些结果进一步证明内溶酶体功能障碍是 p97 相关疾病发病机制的一个关键方面。