Journal of Cell Science 116, e505-e505 (2003)
Copyright © 2003 The Company of Biologists Limited
Rab5: a `kiss and run' suspect
Endocytosed material travels through a series of endocytic compartments
before ending up in lysosomes. Likewise, phagocytosed material eventually
passes to phagolysosomes. `Kiss and run' interactions regulated by the small
GTPase Rab5 move material between compartments in the phagocytic pathway. But
whether the endocytic pathway involves compartment maturation (compatible with
kiss and run) or transport of vesicles between pre-existing compartments is
still not clear. Michel Desjardins and co-workers have followed endocytosis in
macrophages expressing GTPase-defective Rab5a (Rab5Q79L). The
Rab5Q79L-expressing cells possess abnormally large endosomes, which the
authors show display kinetic properties and marker proteins characteristic of
early and late endosomes (see p.
907). They also find that the giant endosomes can initially be
fragmented by bafilomycin A1 — like early endosomes — but that
they subsequently become resistant to the drug — like late endosomes.
These observations thus support the maturation model rather than vesicle
transport. Significantly, the authors are able to demonstrate that
Rab5Q79L-expressing cells lose the ability to segregate endocytosed particles
of different sizes. They therefore conclude that Rab5 regulates transient,
kiss-and-run interactions between endosomes early in lysosome biogenesis
— as in phagolysosome biogenesis.
Related articles in JCS:
- Remodeling of endosomes during lysosome biogenesis involves `kiss and run' fusion events regulated by rab5
- Sophie Duclos, Rachel Corsini, and Michel Desjardins
JCS 2003 116: 907-918.
[Abstract]
[Full Text]
