Ricin-resistant Madin-Darby canine kidney cells missort a major endogenous apical sialoglycoprotein.
gp114 is a major sialoglycoprotein expressed on the apical membrane of Madin-Darby canine kidney (MDCK) II cells. We investigated its distribution in two lectin-resistant mutant cell lines derived from MDCKII cells, MDCKII-RCAr and MDCKII-ConAr cells. gp114 was present on the apical membrane of MDCKII-ConAr cells but was predominantly basolateral in MDCKII-RCAr cells. No change of polarity was observed for several apical and basolateral markers in this cell line. Reversal of polarity of gp114 mainly resulted from a modification of its intracellular sorting. gp114 showed altered endocytosis in MDCKII-RCAr cells. In MDCKII cells gp114 was slowly endocytosed, whereas in MDCKII-RCAr cells endocytosis of gp114 was highly increased. Using mannosidase I and II inhibitors we found that N-glycosylation only slightly affects gp114 sorting and endocytosis. Our results suggest that gp114 or an associated component in MDCK-RCAr fails to express apical information or that a mutation creates a basolateral sorting signal which could be related to endocytic signals.
Le Bivic
A
A
Biologie de la Différenciation Cellulaire, Unité de Recherche associée 179, Faculté des Sciences de Luminy, Marseille, France.
Garcia
M
M
Rodriguez-Boulan
E
E
D000818:Animals; D002460:Cell Line; D016764:Cell Polarity; D004285:Dogs; D004351:Drug Resistance; D005455:Fluorescent Antibody Technique; D006026:Glycoside Hydrolases / Q000378:metabolism; D006031:Glycosylation; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D012276:Ricin / Q000494:pharmacology*; D012795:Sialoglycoproteins / Q000378:metabolism*
D008562:Membrane Glycoproteins; D012795:Sialoglycoproteins; D012276:Ricin; D006026:Glycoside Hydrolases