N-glycans as apical targeting signals in polarized epithelial cells.

2005 ◽  
Vol 72 ◽  
pp. 39-45 ◽  
Author(s):  
Paula Urquhart ◽  
Susan Pang ◽  
Nigel M. Hooper
Keyword(s):  
Epithelial Cells ◽  
Kidney Cells ◽  
Apical Surface ◽  
Madin Darby Canine Kidney ◽  
Targeting Signals ◽  
Polarized Epithelial Cells ◽  
Apical Sorting ◽  
Darby Canine Kidney ◽  
Canine Kidney

MDCK (Madin-Darby canine kidney) cells represent a good model of polarized epithelium to investigate the signals involved in the apical targeting of proteins. As reported previously, GPI (glycosylphosphatidylinositol) anchors mediate the apical sorting of proteins in polarized epithelial cells through their interaction with lipid rafts. However, using a naturally N-glycosylated and GPI-anchored protein, we found that the GPI anchor does not influence the targeting of the protein. It is, in fact, the N-glycans that signal the protein to the apical surface. In the present review, the role of N-glycans and GPI anchors as apical signals is discussed along with the putative mechanisms involved.

scholarly journals SpecificN-Glycans Direct Apical Delivery of Transmembrane, but Not Soluble or Glycosylphosphatidylinositol-anchored Forms of Endolyn in Madin-Darby Canine Kidney Cells

2004 ◽  
Vol 15 (3) ◽  
pp. 1407-1416 ◽  
Author(s):  
Beth A. Potter ◽  
Gudrun Ihrke ◽  
Jennifer R. Bruns ◽  
Kelly M. Weixel ◽  
Ora A. Weisz
Keyword(s):  
Transmembrane Protein ◽  
Site Directed Mutagenesis ◽  
Kidney Cells ◽  
Apical Surface ◽  
Glycosidase Inhibitors ◽  
Madin Darby Canine Kidney ◽  
Reporter Protein ◽  
Apical Sorting ◽  
Darby Canine Kidney ◽  
Canine Kidney

The sialomucin endolyn is a transmembrane protein with a unique trafficking pattern in polarized Madin-Darby canine kidney cells. Despite the presence of a cytoplasmic tyrosine motif that, in isolation, is sufficient to mediate basolateral sorting of a reporter protein, endolyn predominantly traverses the apical surface en route to lysosomes. Apical delivery of endolyn is disrupted in tunicamycin-treated cells, implicating a role for N-glycosylation in apical sorting. Site-directed mutagenesis of endolyn's eight N-glycosylation sites was used to identify two N-glycans that seem to be the major determinants for efficient apical sorting of the protein. In addition, apical delivery of endolyn was disrupted when terminal processing of N-glycans was blocked using glycosidase inhibitors. Missorting of endolyn occurred independently of the presence or absence of the basolateral sorting signal, because apical delivery was also inhibited by tunicamycin when the cytoplasmic tyrosine motif was mutated. However, we found that apical secretion of a soluble mutant of endolyn was N-glycan independent, as was delivery of glycosylphosphatidylinositol-anchored endolyn. Thus, specific N-glycans are only essential for the apical sorting of transmembrane endolyn, suggesting fundamental differences in the mechanisms by which soluble, glycosylphosphatidylinositol-anchored, and transmembrane proteins are sorted.

scholarly journals Mammalian PAR-1 determines epithelial lumen polarity by organizing the microtubule cytoskeleton

2004 ◽  
Vol 164 (5) ◽  
pp. 717-727 ◽  
Author(s):  
David Cohen ◽  
Patrick J. Brennwald ◽  
Enrique Rodriguez-Boulan ◽  
Anne Müsch
Keyword(s):  
Epithelial Cells ◽  
Mdck Cells ◽  
Cell Contact ◽  
Bile Canaliculi ◽  
Madin Darby Canine Kidney ◽  
Lumen Formation ◽  
Contact Sites ◽  
Darby Canine Kidney ◽  
Canine Kidney

Epithelial differentiation involves the generation of luminal surfaces and of a noncentrosomal microtubule (MT) network aligned along the polarity axis. Columnar epithelia (e.g., kidney, intestine, and Madin-Darby canine kidney [MDCK] cells) generate apical lumina and orient MT vertically, whereas liver epithelial cells (hepatocytes and WIFB9 cells) generate lumina at cell–cell contact sites (bile canaliculi) and orient MTs horizontally. We report that knockdown or inhibition of the mammalian orthologue of Caenorhabditis elegans Par-1 (EMK1 and MARK2) during polarization of cultured MDCK and WIFB9 cells prevented development of their characteristic lumen and nonradial MT networks. Conversely, EMK1 overexpression induced the appearance of intercellular lumina and horizontal MT arrays in MDCK cells, making EMK1 the first known candidate to regulate the developmental branching decision between hepatic and columnar epithelial cells. Our experiments suggest that EMK1 primarily promotes reorganization of the MT network, consistent with the MT-regulating role of this gene product in other systems, which in turn controls lumen formation and position.

scholarly journals Similar uptake but different trafficking and escape routes of reovirus virions and infectious subvirion particles imaged in polarized Madin–Darby canine kidney cells

2013 ◽  
Vol 24 (8) ◽  
pp. 1196-1207 ◽  
Author(s):  
Steeve Boulant ◽  
Megan Stanifer ◽  
Comert Kural ◽  
David K. Cureton ◽  
Ramiro Massol ◽  
...  
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Endocytic Pathway ◽  
Cell Entry ◽  
Kidney Cells ◽  
Apical Surface ◽  
Madin Darby Canine Kidney ◽  
Darby Canine Kidney ◽  
Canine Kidney

Polarized epithelial cells that line the digestive, respiratory, and genitourinary tracts form a barrier that many viruses must breach to infect their hosts. Current understanding of cell entry by mammalian reovirus (MRV) virions and infectious subvirion particles (ISVPs), generated from MRV virions by extracellular proteolysis in the digestive tract, are mostly derived from in vitro studies with nonpolarized cells. Recent live-cell imaging advances allow us for the first time to visualize events at the apical surface of polarized cells. In this study, we used spinning-disk confocal fluorescence microscopy with high temporal and spatial resolution to follow the uptake and trafficking dynamics of single MRV virions and ISVPs at the apical surface of live polarized Madin–Darby canine kidney cells. Both types of particles were internalized by clathrin-mediated endocytosis, but virions and ISVPs exhibited strikingly different trafficking after uptake. While virions reached early and late endosomes, ISVPs did not and instead escaped the endocytic pathway from an earlier location. This study highlights the broad advantages of using live-cell imaging combined with single-particle tracking for identifying key steps in cell entry by viruses.

scholarly journals Apical sorting of lysoGPI-anchored proteins occurs independent of association with detergent-resistant membranes but dependent on their N-glycosylation

2013 ◽  
Vol 24 (12) ◽  
pp. 2021-2033 ◽  
Author(s):  
Guillaume Alain Castillon ◽  
Laetitia Michon ◽  
Reika Watanabe
Keyword(s):  
Protein Transport ◽  
Protein Targeting ◽  
Apical Membrane ◽  
Apical Surface ◽  
Madin Darby Canine Kidney ◽  
General Role ◽  
Detergent Resistant Membranes ◽  
Apical Sorting ◽  
Darby Canine Kidney

Most glycosylphosphatidylinositol-anchored proteins (GPI-APs) are located at the apical surface of epithelial cells. The apical delivery of GPI-APs is believed to result from their association with lipid rafts. We find that overexpression of C-terminally tagged PGAP3 caused predominant production of lysoGPI-APs, an intermediate precursor in the GPI lipid remodeling process in Madin–Darby canine kidney cells. In these cells, produced lysoGPI-APs are not incorporated into detergent-resistant membranes (DRMs) but still are delivered apically, suggesting that GPI-AP association with DRMs is not necessary for apical targeting. In contrast, apical transport of both fully remodeled and lyso forms of GPI-APs is dependent on N-glycosylation, confirming a general role of N-glycans in apical protein transport. We also find that depletion of cholesterol causes apical-to-basolateral retargeting not only of fully remodeled GPI-APs, but also of lysoGPI-APs, as well as endogenous soluble and transmembrane proteins that would normally be targeted to the apical membrane. These findings confirm the essential role for cholesterol in the apical protein targeting and further demonstrate that the mechanism of cholesterol-dependent apical sorting is not related to DRM association of GPI-APs.

scholarly journals Transepithelial transport of a viral membrane glycoprotein implanted into the apical plasma membrane of Madin-Darby canine kidney cells. II. Immunological quantitation.

1983 ◽  
Vol 97 (3) ◽  
pp. 638-643 ◽  
Author(s):  
M Pesonen ◽  
K Simons
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Binding Assay ◽  
Protein A ◽  
Apical Plasma Membrane ◽  
Kidney Cells ◽  
Apical Surface ◽  
Madin Darby Canine Kidney ◽  
Darby Canine Kidney ◽  
Canine Kidney

The envelope of vesicular stomatitis virus was fused with the apical plasma membrane of Madin-Darby canine kidney cells by low pH treatment. The fate of the implanted G protein was then followed using a protein A-binding assay, which was designed to quantitate the amount of G protein in the apical and the basolateral membranes. The implanted G protein was rapidly internalized at 31 degrees C, whereas at 10 degrees C no uptake was observed. Already after 15 min at 31 degrees C, a fraction of the G protein could be detected at the basolateral membrane. After 60 min 25-48% of the G protein was basolateral as measured by the protein A-binding assay. At the same time, 25-33% of the implanted G protein was detected at the apical membrane. Internalization of G protein was not affected by 20 mM ammonium chloride or by 10 microM monensin. However, the endocytosed G protein accumulated in intracellular vacuoles and redistribution back to the plasma membrane was inhibited. We conclude that the implanted G protein was rapidly internalized from the apical surface of Madin-Darby canine kidney cells and a major fraction was routed to the basolateral domain.

Polarity of endogenous and exogenous glycosyl-phosphatidylinositol-anchored membrane proteins in Madin-Darby canine kidney cells

1990 ◽  
Vol 96 (1) ◽  
pp. 143-149
Author(s):  
J.M. Wilson ◽  
N. Fasel ◽  
J.P. Kraehenbuhl
Keyword(s):  
Plasma Membrane ◽  
Common Mechanism ◽  
Apical Plasma Membrane ◽  
Kidney Cells ◽  
Apical Surface ◽  
Madin Darby Canine Kidney ◽  
Transfected Cells ◽  
Glycosyl Phosphatidylinositol ◽  
Darby Canine Kidney ◽  
Canine Kidney

Madin-Darby canine kidney cells (MDCK) were transfected with a cDNA encoding the glycosyl-phosphatidylinositol (GPI)-anchored protein mouse Thy-1 in order to study the steady-state surface distribution of exogenous and endogenous GPI-linked proteins. Immunofluorescence of transfected cells grown on collagen-coated coverslips showed that expression of Thy-1 was variable throughout the epithelium, with some cells expressing large amounts of Thy-1 adjacent to very faintly staining cells. Selective surface iodination of cells grown on collagen-coated or uncoated transwell filters followed by immunoprecipitation of Thy-1 demonstrated that all the Thy-1 was present exclusively in the apical plasma membrane. Although cells grown on uncoated filters had much smaller amounts of Thy-1, it was consistently localized on the apical surfaces. Immunofluorescent localization of Thy-1 on 1 micron frozen sections of filter-grown cells demonstrated that all the Thy-1 was on the apical surface and there was no detectable intracellular pool. Phosphatidylinositol-specific phospholipase C digestion of intact iodinated monolayers released Thy-1 only into the apical medium, indicating that Thy-1 was processed normally in transfected cells and was anchored by a GPI-tail. In agreement with previous findings, endogenous GPI-linked proteins were found only on the apical plasma membrane. These results suggest that there is a common mechanism for sorting and targeting of GPI-linked proteins in polarized epithelial cells.

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