Numb positively regulates autophagic flux via regulating lysosomal function
Numb positively regulates autophagic flux via regulating lysosomal function
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Numb 通过调节溶酶体功能积极调节自噬通量
DOI：
10.1016/j.bbrc.2017.07.084
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发表时间：
2017
影响因子：
3.1
通讯作者：
Li Hongchang
中科院分区：
文献类型：
--
作者：
Sun Haiyan;Liu Yi;Zhang Lei;Shao Ximing;Liu Ke;Ding Zhihao;Liu Xianming;Jiang Changan;Li Huashun;Li Hongchang
自噬是一种依赖于溶酶体的分解代谢过程，涉及不必要或受损的蛋白质和细胞器的降解和再循环。新的证据表明，自噬功能障碍与多种人类疾病密切相关，包括癌症、衰老、肌病和神经退行性疾病。在这里，利用基因敲除，我们发现了Numb，一种内吞适配蛋白，在调节自噬的后期步骤中所起的作用。通过RFP-LC_3染色结合电子显微镜观察，我们发现数耗竭导致自噬空泡的积累。进一步的研究表明，数字耗竭通过抑制溶酶体酶(组织蛋白酶D、β-葡萄糖醛酸酶和β-葡萄糖苷酶)的活性来损害自噬降解。此外，数字耗竭导致溶酶体的pH值升高和糖基化的溶酶体膜蛋白减少。我们进一步观察到，在数量耗尽的细胞中，Rab7的活性受到抑制。总之，我们的发现揭示了Numb在调节自噬事件中的一种新功能及其可能的机制。
Autophagy is a lysosome-dependent catabolic process involving in the degradation and recycling of unnecessary or damaged proteins and organelles. Emerging evidence indicates that autophagy dysfunction is closely related to various human diseases including cancer, aging, myopathies and neurodegenerative disorders. Here, using genetic knockdown, we uncover the role of Numb, an endocytic adaptor protein, in regulating the late steps of autophagy. We found that Numb depletion led to the accumulation of autophagic vacuole, as verified by RFP-LC3 staining combined with transmission electron microscopy. Further investigation indicated that Numb depletion impaired autophagic degradation through inhibiting the activities of lysosomal enzymes (Cathepsin D, β-glucuronidase and β-glucosidase). Moreover, Numb depletion induced elevation of lysosomal pH values and decrease of glycosylated lysosome-associated membrane proteins. We further observed that Rab7 activity was inhibited in Numb-depleted cells. Together, our findings revealed a novel function of Numb and its likely mechanism in regulation of autophagy events.