<italic>N</italic>-glycosylation at Asn residues 554 and 566 of E-cadherin affects cell cycle progression through extracellular signal-regulated protein kinase signaling pathway

Abstract

<title>Abstract</title> E-cadherin, which has a widely acknowledged role in mediating calcium-dependent cell-cell adhesion between epithelial cells, also functions as a tumor suppressor. The ectodomain of human E-cadherin contains four potential <italic>N</italic>-glycosylation sites at Asn residues 554, 566, 618, and 633. We investigated the role of E-cadherin <italic>N</italic>-glycosylation in cell cycle progression by site-directed mutagenesis. We showed previously that all four potential <italic>N</italic>-glycosylation sites of E-cadherin were <italic>N</italic>-glycosylated in human breast carcinoma MDA-MB-435 cells. Removal of <italic>N</italic>-glycan at Asn633 dramatically affected E-cadherin stability. In this study we showed that E-cadherin mutant missing <italic>N</italic>-glycans at Asn554, Asn566 and Asn618 failed to induce cell cycle arrest in G₁ phase and to suppress cell proliferation in comparison with wild-type E-cadherin. Moreover, <italic>N</italic>-glycans at Asn554 and Asn566, but not at Asn618, seemed to be indispensable for E-cadherin-mediated suppression of cell cycle progression. Removal of <italic>N</italic>-glycans at either Asn554 or Asn566 of E-cadherin was accompanied with the activation of the extracellular signal-regulated protein kinase signaling pathway. After treatment with PD98059, an inhibitor of the extracellular signal-regulated protein kinase signaling pathway, wild-type E-cadherin transfected MDA-MB-435 and E-cadherin <italic>N</italic>-glycosylation-deficient mutant transfected MDA-MB-435 cells had equivalent numbers of cells in G₁ phase. These findings implied that <italic>N</italic>-glycosylation might be crucial for E-cadherin-mediated suppression of cell cycle progression. <b>FullText for HTML: </b><a target="_blank" class="col_4A90E2" href="https://doi.org/10.1111/j.1745-7270.2008.00380.x">https://doi.org/10.1111/j.1745-7270.2008.00380.x</a>