文摘
Our previous studies showed that cell surface ¦Â1,4-galactosyltransferase 1 (¦Â1,4GT1) negatively regulated cell survival through inhibition and modulation of the epidermal growth factor receptor (EGFR) signaling pathway in human hepatocellular carcinoma (HCC) SMMC-7721 cells. However, the underlying mechanism remains unclear. Here we demonstrated that ¦Â1,4-galactosyltransferase 1 (¦Â1,4GT1) interacted with EGFR in vitro by GST pull-down analysis. Furthermore, we demonstrated that ¦Â1,4GT1 bound to EGFR in vivo by co-immunoprecipitation and determined the co-localization of ¦Â1,4GT1 and EGFR on the cell surface via confocal laser scanning microscopy analysis. Finally, using 125I-EGF binding experiments and Western blot analysis, we found that overexpression of ¦Â1,4GT1 inhibited 125I-EGF binding to EGFR, and consequently reduced the levels of EGFR dimerization and phosphorylation. In contrast, RNAi-mediated knockdown of ¦Â1,4GT1 increased the levels of EGFR dimerization and phosphorylation. These data suggest that cell surface ¦Â1,4GT1 interacts with EGFR and inhibits EGFR activation.
