Regulation of myosin-VI targeting to endocytic compartments.
Myosin-VI has been implicated in endocytic trafficking at both the clathrin-coated and uncoated vesicle stages. The identification of alternative splice forms led to the suggestion that splicing defines the vesicle type to which myosin-VI is recruited. In contrast to this hypothesis, we find that in all cell types examined, myosin-VI is associated with uncoated endocytic vesicles, regardless of splice form. GIPC, a PDZ-domain containing adapter protein, co-assembles with myosin-VI on these vesicles. Myosin-VI is only recruited to clathrin-coated vesicles in cells that express high levels of Dab2, a clathrin-binding adapter protein. Overexpression of Dab2 is sufficient to reroute myosin-VI to clathrin-coated pits in cells where myosin-VI is normally associated with uncoated vesicles. In normal rat kidney (NRK) cells, which express high endogenous levels of Dab2, splicing of the globular tail domain further modulates targeting of ectopically expressed myosin-VI. Although myosin-VI can be recruited to clathrin-coated pits, we find no requirement for myosin-VI motor activity in endocytosis in NRK cells. Instead, our data suggest that myosin-VI recruitment to clathrin-coated pits may be an early step in the recruitment of GIPC to the vesicle surface.
Dance
Amber L
AL
Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093, USA.
Miller
Matthew
M
Seragaki
Shinobu
S
Aryal
Prafulla
P
White
Breanne
B
Aschenbrenner
Laura
L
Hasson
Tama
T
D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D017398:Alternative Splicing / Q000235:genetics / Q000502:physiology*; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D049452:Green Fluorescent Proteins; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D013552:Swine; D022161:Transport Vesicles / Q000378:metabolism*
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; C115271:Gipc1 protein, mouse; D009479:Neuropeptides; C089785:myosin VI; D049452:Green Fluorescent Proteins; D018995:Myosin Heavy Chains