Journal of Cell Science 115, e2105-e2105 (2002)
Copyright © 2002 The Company of Biologists Limited
doi:
LGP85 and endosome maintenance
Lysosomes and late endosomes are thought to exist in dynamic equilibrium,
undergoing repeated cycles of fission and fusion. Their limiting membranes
contain a common set of highly glycosylated transmembrane proteins, including
LAMP-1, LAMP-2 and LGP85 (also known as LIMP-II). Whether these proteins are
involved in endosome/lysosome dynamics or play some other role is unclear. To
investigate the possibility, Yoshitaka Tanaka and co-workers have
overexpressed them in COS cells. They observe that overexpression of LGP85
(but not LAMP-1 or LAMP-2) induces formation of abnormally large endosome-like
structures (see p. 4117).
Transport of cargo out of these structures is blocked, and they accumulate
free cholesterol. Interestingly, the authors show that coexpression of a
dominant-negative form of Rab5b (a GTPase that functions in
endosomal/lysosomal membrane trafficking) inhibits the effect of LGP85,
implicating the GTPase in formation of the large endosomes. Tanaka and
co-workers thus propose that LGP85 is important for the biogenesis and
maintenance of endosomes/lysosomes and drives their reorganization by
interacting with components of the vesicle fission/fusion machinery.
Related articles in JCS:
- A role for the lysosomal membrane protein LGP85 in the biogenesis and maintenance of endosomal and lysosomal morphology
- Toshio Kuronita, Eeva-Liisa Eskelinen, Hideaki Fujita, Paul Saftig, Masaru Himeno, and Yoshitaka Tanaka
JCS 2002 115: 4117-4131.
[Abstract]
[Full Text]
