Affordable Access

A role for Rab5 activity in the biogenesis of endosomal and lysosomal compartments.

Authors
  • Hirota, Yuko
  • Kuronita, Toshio
  • Fujita, Hideaki
  • Tanaka, Yoshitaka
Type
Published Article
Journal
Biochemical and Biophysical Research Communications
Publisher
Elsevier
Publication Date
Dec 07, 2007
Volume
364
Issue
1
Pages
40–47
Identifiers
PMID: 17927960
Source
Medline
License
Unknown

Abstract

Rab5 is a small GTPase that plays roles in the homotypic fusion of early endosomes and regulation of intracellular vesicle transport. We show here that expression of GFP-tagged GTPase-deficient form of Rab5b (Rab5bQ79L) in NRK cells results in the sequential formation of three morphologically and functionally distinct types of endosomes. Expression of GFP-Rab5bQ79L initially caused a homotypic fusion of early endosomes accompanying a redistribution of the TGN-resident cargo molecules, and subsequent fusion with late endosomes/lysosomes, leading to the formation of giant hybrid organelles with features of early endosomes and late endosomes/lysosomes. Surprisingly, the giant endosomes gradually fragmented and shrunk, leading to the accumulation of early endosome clusters and concurrent reformation of late endosomes/lysosomes, a process accelerated by treatment with a phosphatidylinositol-3-kinase (PI(3)K) inhibitor, wortmannin. We postulate that such sequential processes reflect the biogenesis and maintenance of late endosomes/lysosomes, presumably via direct fusion with early endosomes and subsequent fission from hybrid organelles. Thus, our findings suggest a regulatory role for Rab5 in not only the early endocytic pathway, but also the late endocytic pathway, of membrane trafficking in coordination with PI(3)K activity.

Report this publication

Statistics

Seen <100 times