Vacuolin-1 potently and reversibly inhibits autophagosome-lysosome fusion by activating RAB5A

Yingying Lu, Shichen Dong, Baixia Hao, Chang Li, Kaiyuan Zhu, Wenjing Guo, Qian Wang, King Ho Cheung, Connie WM Wong, Wu Tian Wu, Huss Markus, Jianbo Yue*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

91 Citations (Scopus)

Abstract

Autophagy is a catabolic lysosomal degradation process essential for cellular homeostasis and cell survival. Dysfunctional autophagy has been associated with a wide range of human diseases, e.g., cancer and neurodegenerative diseases. A large number of small molecules that modulate autophagy have been widely used to dissect this process and some of them, e.g., chloroquine (CQ), might be ultimately applied to treat a variety of autophagy-associated human diseases. Here we found that vacuolin-1 potently and reversibly inhibited the fusion between autophagosomes and lysosomes in mammalian cells, thereby inducing the accumulation of autophagosomes. Interestingly, vacuolin-1 was less toxic but at least 10-fold more potent in inhibiting autophagy compared with CQ. Vacuolin-1 treatment also blocked the fusion between endosomes and lysosomes, resulting in a defect in general endosomal-lysosomal degradation. Treatment of cells with vacuolin-1 alkalinized lysosomal pH and decreased lysosomal Ca2+ content. Besides marginally inhibiting vacuolar ATPase activity, vacuolin-1 treatment markedly activated RAB5A GTPase activity. Expression of a dominant negative mutant of RAB5A or RAB5A knockdown significantly inhibited vacuolin-1-induced autophagosome-lysosome fusion blockage, whereas expression of a constitutive active form of RAB5A suppressed autophagosome-lysosome fusion. These data suggest that vacuolin-1 activates RAB5A to block autophagosome-lysosome fusion. Vacuolin-1 and its analogs present a novel class of drug that can potently and reversibly modulate autophagy.

Original languageEnglish
Pages (from-to)1895-1905
Number of pages11
JournalAutophagy
Volume10
Issue number11
DOIs
Publication statusPublished - 2 Nov 2014
Externally publishedYes

User-Defined Keywords

  • vacuolin-1
  • autophagosomes
  • lysosomes
  • RAB5A
  • pH
  • endosomes

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