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

• Published in: The Journal of biological chemistry 2010-10, Vol.285 (41), p.31164-31173
• Main Authors: Sengupta, Pritam K, Bouchie, Meghan P, Kukuruzinska, Maria A
• Format: Article
• Language: English
• ISSN: 0021-9258
• DOI: 10.1074/jbc.M110.149195

Protein N-glycosylation and the Wnt/b-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/b-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), Madin-Darby canine kidney (MDCK), and human epidermoid carcinoma (A253) cells contain the T-cell factor/lymphoid enhancer-binding 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 b-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 b-catenin. Chromatin immunoprecipitation analysis confirmed the presence of b-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 g-catenin, a close homologue of b-catenin, although not in a lithium chloride-dependent manner. Our results provide the first evidence that the Wnt/b-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 g-catenin at the DPAGT1 promoter.