Referenced in: none

Automatically associated channels: TRP , TRPM , TRPML , TRPML1

Title: PI(3,5)P(2) controls membrane trafficking by direct activation of mucolipin Ca(2+) release channels in the endolysosome.

Authors: Xian-Ping Dong, Dongbiao Shen, Xiang Wang, Taylor Dawson, Xinran Li, Qi Zhang, Xiping Cheng, Yanling Zhang, Lois S Weisman, Markus Delling, Haoxing Xu

Journal, date & volume: Nat Commun, 2010 , 1, 38

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/20802798

Abstract
Membrane fusion and fission events in intracellular trafficking are controlled by both intraluminal Ca(2+) release and phosphoinositide (PIP) signalling. However, the molecular identities of the Ca(2+) release channels and the target proteins of PIPs are elusive. In this paper, by direct patch-clamping of the endolysosomal membrane, we report that PI(3,5)P(2), an endolysosome-specific PIP, binds and activates endolysosome-localized mucolipin transient receptor potential (TRPML) channels with specificity and potency. Both PI(3,5)P(2)-deficient cells and cells that lack TRPML1 exhibited enlarged endolysosomes/vacuoles and trafficking defects in the late endocytic pathway. We find that the enlarged vacuole phenotype observed in PI(3,5)P(2)-deficient mouse fibroblasts is suppressed by overexpression of TRPML1. Notably, this PI(3,5)P(2)-dependent regulation of TRPML1 is evolutionarily conserved. In budding yeast, hyperosmotic stress induces Ca(2+) release from the vacuole. In this study, we show that this release requires both PI(3,5)P(2) production and a yeast functional TRPML homologue. We propose that TRPMLs regulate membrane trafficking by transducing information regarding PI(3,5)P(2) levels into changes in juxtaorganellar Ca(2+), thereby triggering membrane fusion/fission events.