Vps34 regulates Rab7 and late endocytic trafficking through recruitment of the GTPase-activating protein Armus.
J Cell Sci
; 129(23): 4424-4435, 2016 12 01.
Article
in En
| MEDLINE
| ID: mdl-27793976
ABSTRACT
The class III phosphoinositide 3-kinase (PI3K) Vps34 (also known as PIK3C3 in mammals) produces phosphatidylinositol 3-phosphate [PI(3)P] on both early and late endosome membranes to control membrane dynamics. We used Vps34-deficient cells to delineate whether Vps34 has additional roles in endocytic trafficking. In Vps34-/- mouse embryonic fibroblasts (MEFs), transferrin recycling and EEA1 membrane localization were unaffected despite elevated Rab5-GTP levels. Strikingly, a large increase in Rab7-GTP levels, an accumulation of enlarged late endosomes, and decreased EGFR degradation were observed in Vps34-deficient cells. The hyperactivation of Rab7 in Vps34-deficient cells stemmed from the failure to recruit the Rab7 GTPase-activating protein (GAP) Armus (also known as TBC1D2), which binds to PI(3)P, to late endosomes. Protein-lipid overlay and liposome-binding assays reveal that the putative pleckstrin homology (PH) domain in Armus can directly bind to PI(3)P. Elevated Rab7-GTP led to the failure of intraluminal vesicle (ILV) formation and lysosomal maturation. Rab7 silencing and Armus overexpression alleviated the vacuolization seen in Vps34-deficient cells. Taken together, these results demonstrate that Vps34 has a previously unknown role in regulating Rab7 activity and late endosomal trafficking.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Rab GTP-Binding Proteins
/
GTPase-Activating Proteins
/
Endocytosis
/
Class III Phosphatidylinositol 3-Kinases
Limits:
Animals
/
Humans
Language:
En
Journal:
J Cell Sci
Year:
2016
Document type:
Article
Affiliation country:
United States