Ishikawa Kei-Ichi, Saiki Shinji, Furuya Norihiko, Imamichi Yoko, Tsuboi Yoshio, Hattori Nobutaka
Department of Neurology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Department of Neurology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan; Division of Development of Autophagy Modulating Drugs, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Neurosci Lett. 2019 Jan 18;690:181-187. doi: 10.1016/j.neulet.2018.10.036. Epub 2018 Oct 23.
Dynein-dynactin has an indispensable role in autophagy and p150 is the largest component of the dynactin complex. Here, we characterized the effects of knockdown (KD) of endogenous p150 and of the pathogenic mutation of p150 found in autosomal dominant p150-associated disorders [hereditary motor neuronopathy with vocal paresis (HMN7B) and Perry syndrome] on autophagy. Overexpression of the p150 pathogenic mutant or siRNA KD of p150 promoted the localization of lysosomes at the cell periphery and increased the number of autophagosomes, suggesting partial blockage of autophagic flux. Surprisingly, although autophagosomes and lysosomes were redistributed predominantly to the cell periphery in p150-KD cells, the autolysosome formation ratio was preserved. However, under autophagy activation conditions induced by starvation, the ratio of autophagosome-lysosome fusion in p150-KD cells was decreased in the early phase. Our data demonstrate that functional loss of p150 may cause autophagic insufficiency, which may be associated with the pathogenesis of p150-associated disorders.
动力蛋白-动力蛋白激活蛋白在自噬过程中发挥着不可或缺的作用，而p150是动力蛋白激活蛋白复合体中最大的组成部分。在此，我们研究了内源性p150基因敲低（KD）以及在常染色体显性p150相关疾病[伴有声带麻痹的遗传性运动神经元病（HMN7B）和佩里综合征]中发现的p150致病突变对自噬的影响。p150致病突变体的过表达或p150的小干扰RNA（siRNA）基因敲低促进了溶酶体在细胞周边的定位，并增加了自噬体的数量，这表明自噬流存在部分阻断。令人惊讶的是，尽管在p150基因敲低的细胞中自噬体和溶酶体主要重新分布到细胞周边，但自噬溶酶体的形成比例保持不变。然而，在饥饿诱导的自噬激活条件下，p150基因敲低细胞中自噬体-溶酶体融合的比例在早期阶段有所降低。我们的数据表明，p150的功能丧失可能导致自噬功能不全，这可能与p150相关疾病的发病机制有关。
