title: Coordinate regulation of N-glycosylation gene DPAGT1, canonical Wnt signaling and E-cadherin adhesion.
abstract: The metabolic pathway of protein N-glycosylation influences intercellular adhesion by affecting the composition and cytoskeletal association of E-cadherin protein complexes, or adherens junctions (AJs). In sparse cells, E-cadherin is modified extensively with complex N-glycans and forms nascent AJs, while in dense cultures, hypoglycosylated E-cadherin drives the assembly of mature AJs with increased levels of γ- and α-catenins. N-glycosylation of E-cadherin is controlled by the DPAGT1 gene, a key regulator of the N-glycosylation pathway. DPAGT1 is a target of the canonical Wnt signaling pathway, with both β- and γ-catenins binding to Tcf at its promoter. We now report that DPAGT1 senses cell density through canonical Wnt signaling. In dense cells, depletion of β-catenin from the DPAGT1 promoter correlated with downregulation of its cellular abundance, while loss of nuclear γ-catenin reflected its greater recruitment to AJs. DPAGT1 itself affected canonical Wnt signaling, with forced changes in its expression resulting in corresponding changes in transcriptionally active β-catenin and canonical Wnt activity. Remarkably, a 2.4-fold increase in the DPAGT1 mRNA level resulted in increased N-glycosylation and reduced membrane localization of E-cadherin, coincident with dramatic changes in cell morphology. Lastly, we present evidence that N-glycosylation status of E-cadherin controls its antagonism of canonical Wnt signaling. Transfection of hypoglycosylated E-cadherin mutant, V13, but not fully N-glycosylated E-cadherin, into sparse cells inhibited canonical Wnt activity by depleting nuclear β- and γ-catenins. Collectively, our studies show that cells coordinate DPAGT1 expression and protein N-glycosylation with canonical Wnt signaling and E-cadherin adhesion via positive and negative feedback mechanisms.
authors.affiliation: Department of Molecular and Cell Biology, Boston University Medical Center, 72 East Concord Street, EVANS-E438, Boston, MA 02118, USA.
authors.forename: Pritam K
authors.initials: PK
authors.lastname: Sengupta
authors.forename: Meghan P
authors.initials: MP
authors.lastname: Bouchie
authors.forename: Mihai
authors.initials: M
authors.lastname: Nita-Lazar
authors.forename: Hsiao-Ying
authors.initials: HY
authors.lastname: Yang
authors.forename: Maria A
authors.initials: MA
authors.lastname: Kukuruzinska
mesh_terms: D000818:Animals; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000235:genetics* / Q000502:physiology; D004285:Dogs; D006031:Glycosylation; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D015820:Cadherins; D051153:Wnt Proteins; D017351:N-Acetylglucosaminyltransferases; C047835:dolichyl-phosphate alpha-N-acetylglucosaminyltransferase