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Open Access Highly Accessed Research article

Acetylated microtubules are required for fusion of autophagosomes with lysosomes

Rui Xie, Susan Nguyen, Wallace L McKeehan and Leyuan Liu*

Author Affiliations

Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030-3303, USA

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BMC Cell Biology 2010, 11:89  doi:10.1186/1471-2121-11-89

Published: 22 November 2010

Abstract

Background

Autophagy is a dynamic process during which isolation membranes package substrates to form autophagosomes that are fused with lysosomes to form autolysosomes for degradation. Although it is agreed that the LC3II-associated mature autophagosomes move along microtubular tracks, it is still in dispute if the conversion of LC3I to LC3II before autophagosomes are fully mature and subsequent fusion of mature autophagosomes with lysosomes require microtubules.

Results

We use biochemical markers of autophagy and a collection of microtubule interfering reagents to test the question. Results show that interruption of microtubules with either microtubule stabilizing paclitaxel or destabilizing nocodazole similarly impairs the conversion of LC3I to LC3II, but does not block the degradation of LC3II-associated autophagosomes. Acetylation of microtubules renders them resistant to nocodazole treatment. Treatment with vinblastine that causes depolymerization of both non-acetylated and acetylated microtubules results in impairment of both LC3I-LC3II conversion and LC3II-associated autophagosome fusion with lysosomes.

Conclusions

Acetylated microtubules are required for fusion of autophagosomes with lysosomes to form autolysosomes.