Hypoglycosylated E-cadherin promotes the assembly of tight junctions through the recruitment of PP2A to adherens junctions.
Epithelial cell-cell adhesion is controlled by multiprotein complexes that include E-cadherin-mediated adherens junctions (AJs) and ZO-1-containing tight junctions (TJs). Previously, we reported that reduction of E-cadherin N-glycosylation in normal and cancer cells promoted stabilization of AJs through changes in the composition and cytoskeletal association of E-cadherin scaffolds. Here, we show that enhanced interaction of hypoglycosylated E-cadherin-containing AJs with protein phosphatase 2A (PP2A) represents a mechanism for promoting TJ assembly. In MDCK cells, attenuation of cellular N-glycosylation with siRNA to DPAGT1, the first gene in the N-glycosylation pathway, reduced N-glycosylation of surface E-cadherin and resulted in increased recruitment of stabilizing proteins gamma-catenin, alpha-catenin, vinculin and PP2A to AJs. Greater association of PP2A with AJs correlated with diminished binding of PP2A to ZO-1 and claudin-1 and with increased pools of serine-phosphorylated ZO-1 and claudin-1. More ZO-1 was found in complexes with occludin and claudin-1, and this corresponded to enhanced transepithelial resistance (TER), indicating physiological assembly of TJs. Similar maturation of AJs and TJs was detected after transfection of MDCK cells with the hypoglycosylated E-cadherin variant, V13. Our data indicate that E-cadherin N-glycans coordinate the maturity of AJs with the assembly of TJs by affecting the association of PP2A with these junctional complexes.
Nita-Lazar
Mihai
M
Department of Molecular and Cell Biology, Boston University Medical Center, Boston, MA 02118, USA.
Rebustini
Ivan
I
Walker
Janice
J
Kukuruzinska
Maria A
MA
D022005:Adherens Junctions / Q000378:metabolism*; D000818:Animals; D015820:Cadherins / Q000737:chemistry* / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D062445:Claudin-1; D004285:Dogs; D006031:Glycosylation; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D055550:Protein Stability; D034741:RNA, Small Interfering / Q000235:genetics; D019108:Tight Junctions / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
D015820:Cadherins; D062445:Claudin-1; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D062826:Zonula Occludens-1 Protein; D017351:N-Acetylglucosaminyltransferases; C047835:dolichyl-phosphate alpha-N-acetylglucosaminyltransferase; D054648:Protein Phosphatase 2