Journal
EMBO JOURNAL
Volume 38, Issue 8, Pages -Publisher
WILEY
DOI: 10.15252/embj.2018100312
Keywords
autophagy; lysosome; phosphatidylinositol 4-kinase; phosphoinositide; Rab7
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Funding
- Eunice Kennedy Shriver NICHD, at the National Institutes of Health
- EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT [ZIAHD000196] Funding Source: NIH RePORTER
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The small GTPase Rab7 is a key organizer of receptor sorting and lysosomal degradation by recruiting of a variety of effectors depending on its GDP/GTP-bound state. However, molecular mechanisms that trigger Rab7 inactivation remain elusive. Here we find that, among the endosomal pools, Rab7-positive compartments possess the highest level of PI4P, which is primarily produced by PI4K2A kinase. Acute conversion of this endosomal PI4P to PI(4,5)P-2 causes Rab7 dissociation from late endosomes and releases a regulator of autophagosome-lysosome fusion, PLEKHM1, from the membrane. Rab7 effectors Vps35 and RILP are not affected by acute PI(4,5)P-2 production. Deletion of PI4K2A greatly reduces PIP5K gamma-mediated PI(4,5)P-2 production in Rab7-positive endosomes leading to impaired Rab7 inactivation and increased number of LC3-positive structures with defective autophagosome-lysosome fusion. These results reveal a late endosomal PI4P-PI(4,5)P-2-dependent regulatory loop that impacts autophagosome flux by affecting Rab7 cycling and PLEKHM1 association.
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