Brefeldin A rapidly disrupts plasma membrane polarity by blocking polar sorting in common endosomes of MDCK cells.
Recent studies showing thorough intermixing of apical and basolateral endosomes have demonstrated that endocytic sorting is critical to maintaining the plasma membrane polarity of epithelial cells. Our studies of living, polarized cells show that disrupting endocytosis with brefeldin-A rapidly destroys the polarity of transferrin receptors in MDCK cells while having no effect on tight junctions. Brefeldin-A treatment induces tubulation of endosomes, but the sequential compartments and transport steps of the transcytotic pathway remain intact. Transferrin is sorted from LDL, but is then missorted from common endosomes to the apical recycling endosome, as identified by its nearly neutral pH, and association with GFP chimeras of Rabs 11a and 25. From the apical recycling endosome, transferrin is then directed to the apical plasma membrane. These data are consistent with a model in which polarized sorting of basolateral membrane proteins occurs via a brefeldin-A-sensitive process of segregation into basolateral recycling vesicles. Although disruption of polar sorting correlates with dissociation of gamma-adaptin from endosomes, gamma-adaptin does not appear to be specifically involved in sorting into recycling vesicles, as we find it associated with the transcytotic pathway, and particularly to the post-sorting transcytotic apical recycling endosome.
Wang
E
E
Department of Medicine, Division of Nephrology, Indiana University Medical Center, Indianapolis, IN 46202, USA.
Pennington
J G
JG
Goldenring
J R
JR
Hunziker
W
W
Dunn
K W
KW
D033982:Adaptor Protein Complex gamma Subunits; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D020126:Brefeldin A / Q000378:metabolism* / Q000494:pharmacology; D002451:Cell Compartmentation / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D011992:Endosomes / Q000378:metabolism*; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D011817:Rabbits; D011990:Receptors, Transferrin / Q000378:metabolism*; D014168:Transferrin / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000099193:rab11 GTP-Binding Proteins
D033982:Adaptor Protein Complex gamma Subunits; D020126:Brefeldin A; D007070:Immunoglobulin A; D008565:Membrane Proteins; D011990:Receptors, Transferrin; D014168:Transferrin; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C082888:Rab25 protein, Oryctolagus cuniculus