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Nat Cell Biol. 2016 Apr;18(4):404-17. doi: 10.1038/ncb3324. Epub 2016 Mar 7.

A molecular mechanism to regulate lysosome motility for lysosome positioning and tubulation.

Author information

1
Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 3089 Natural Science Building (Kraus), 830 North University, Ann Arbor, Michigan 48109, USA.
2
Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China.

Abstract

To mediate the degradation of biomacromolecules, lysosomes must traffic towards cargo-carrying vesicles for subsequent membrane fusion or fission. Mutations of the lysosomal Ca(2+) channel TRPML1 cause lysosomal storage disease (LSD) characterized by disordered lysosomal membrane trafficking in cells. Here we show that TRPML1 activity is required to promote Ca(2+)-dependent centripetal movement of lysosomes towards the perinuclear region (where autophagosomes accumulate) following autophagy induction. ALG-2, an EF-hand-containing protein, serves as a lysosomal Ca(2+) sensor that associates physically with the minus-end-directed dynactin-dynein motor, while PtdIns(3,5)P(2), a lysosome-localized phosphoinositide, acts upstream of TRPML1. Furthermore, the PtdIns(3,5)P(2)-TRPML1-ALG-2-dynein signalling is necessary for lysosome tubulation and reformation. In contrast, the TRPML1 pathway is not required for the perinuclear accumulation of lysosomes observed in many LSDs, which is instead likely to be caused by secondary cholesterol accumulation that constitutively activates Rab7-RILP-dependent retrograde transport. Ca(2+) release from lysosomes thus provides an on-demand mechanism regulating lysosome motility, positioning and tubulation.

PMID:
26950892
PMCID:
PMC4871318
DOI:
10.1038/ncb3324
[Indexed for MEDLINE]
Free PMC Article

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