N-Glycosylation Gene DPAGT1 Is a Target of the Wnt/β-Catenin Signaling Pathway

Abstract

Protein N-glycosylation and the Wnt/␤-catenin signaling pathways play critical roles in development and cancer. Although N-glycosylation has been shown to influence Wnt signaling through its effects on Wnt ligands, it is unclear whether the Wnt/␤-catenin pathway impacts protein N-glycosylation. In this study, we show that promoters of the first N-glycosylation gene, DPAGT1, from Chinese hamster ovary (CHO), MadinDarby canine kidney (MDCK), and human epidermoid carcinoma (A253) cells contain the T-cell factor/lymphoid enhancerbinding factor (TCF/LEF) consensus sequence. Treatment of cells with a Wnt activator, lithium chloride, up-regulated DPAGT1 transcript levels that correlated with an increase in the ␤-catenin abundance. Furthermore, exposure of cells to a Wnt receptor ligand, Wnt3a, resulted in an increase in the DPAGT1 transcript levels that was abrogated by the Wnt inhibitor, Dickkopf-1. DNA mobility shift assays revealed specific protein complexes at the DPAGT1 TCF/LEF binding region that were competed off with antibodies to either Tcf3/4 or ␤-catenin. Chromatin immunoprecipitation analysis confirmed the presence of ␤-catenin at the DPAGT1 promoter in vivo. In addition, the DPAGT1 TCF/LEF sequence drove the expression of the luciferase reporter gene. Furthermore, up-regulation of DPAGT1 transcripts by Wnt3a led to altered N-glycosylation of E-cadherin. Interestingly, the DPAGT1 TCF/LEF sequence also interacted with ␥-catenin, a close homologue of ␤-catenin, although not in a lithium chloride-dependent manner. Our results provide the first evidence that the Wnt/␤-catenin signaling pathway regulates the metabolic pathway of protein N-glycosylation by targeting DPAGT1 expression. Moreover, they suggest the existence of another regulatory mechanism involving the interaction of Tcf with ␥-catenin at the DPAGT1 promoter.

N-Glycosylation Induces the CTHRC1 Protein and Drives Oral Cancer Cell Migration

“…We conclude that a hyperglycosylated CTHRC1 glycoform exists in OSCC. Because CTHRC1 has only one N-glycan consensus sequence, and activation of the N-glycosylation pathway is typically accompanied by greater modification with complex and more highly branched N-glycans (15,17), our results indicate enhanced N-glycan heterogeneity on CTHRC1 in OSCC.…”

A compound heterozygous mutation in DPAGT1 results in a congenital disorder of glycosylation with a relatively mild phenotype

“…Most recently, the DPAGT1 gene has been described as a target of Wnt/b-catenin signaling pathway, which have multiple vital and crucial roles in development. 22 This pathway might explain the brain structural anomalies, which can arise during the morphogenetic process of the brain development.…”

Coordinate regulation of N-glycosylation gene DPAGT1, canonical Wnt signaling and E-cadherin adhesion

“…Canonical Wnt signaling has been shown to regulate, and to be antagonized by, E-cadherin adhesion, a key regulator of cell polarity, proliferation and survival in epithelial tissues (Brembeck et al, 2006;Heuberger and Birchmeier, 2010). Recently, the metabolic pathway of protein N-glycosylation has been shown to affect E-cadherin adhesion and to be a target of canonical Wnt signaling (Liwosz et al, 2006;Nita-Lazar et al, 2010;Sengupta et al, 2010). This suggested reciprocal interactions among canonical Wnt, protein N-glycosylation and E-cadherin adhesion.…”

“…DPAGT1 encodes the dolichol-Pdependent N-acetylglucosamine-1-phosphate-transferase (GPT) that initiates the synthesis of the lipid-linked oligosaccharide (LLO) precursor for protein N-glycosylation in the endoplasmic reticulum (ER) (Helenius and Aebi, 2001;Kukuruzinska and Lennon, 1998). DPAGT1 functions at the rate limiting step in the N-glycosylation pathway, and modest changes in its expression lead to robust changes in the N-glycosylation capacity of cells and N-glycosylation status of proteins (Clark et al, 1983;Hayes and Lucas, 1983;Meissner et al, 1999;Mendelsohn et al, 2005;Sengupta et al, 2010;Welply et al, 1985).…”