Wnt/beta-catenin signaling down-regulates N-acetylglucosaminyltransferase III expression: the implications of two mutually exclusive pathways for regulation.
In previous studies, we reported that N-acetylglucosaminyltransferase III (GnT-III) activity and the enzyme product, bisected N-glycans, both were induced in cells cultured under dense conditions in an E-cadherin-dependent manner (Iijima, J., Zhao, Y., Isaji, T., Kameyama, A., Nakaya, S., Wang, X., Ihara, H., Cheng, X., Nakagawa, T., Miyoshi, E., Kondo, A., Narimatsu, H., Taniguchi, N., and Gu, J. (2006) J. Biol. Chem. 281, 13038-13046). Furthermore, we found that α-catenin, a component of the E-cadherin-catenin complex, was also required for this induction (Akama, R., Sato, Y., Kariya, Y., Isaji, T., Fukuda, T., Lu, L., Taniguchi, N., Ozawa, M., and Gu, J. (2008) Proteomics 8, 3221-3228). To further explore the molecular mechanism of this regulation, the roles of β-catenin, an essential molecule in both cadherin-mediated cell adhesion and canonical Wnt signaling, were investigated. Unexpectedly, shRNA knockdown of β-catenin resulted in a dramatic increase in GnT-III expression and its product, the bisected N-glycans, which was confirmed by RT-PCR and GnT-III activity and by E4-PHA lectin blot analysis. The induction of GnT-III expression increased bisecting GlcNAc residues on β1 integrin, which led to down-regulation of integrin-mediated cell adhesion and cell migration. Immunostaining showed that nuclear localization of β-catenin was greatly suppressed; intriguingly, the knockdown of β-catenin in the nuclei was more effective than that in cell-cell contacts in the knockdown cells, which was also confirmed by Western blot analysis. Stimulation of the Wnt signaling pathway by the addition of exogenous Wnt3a or BIO, a GSK-3β inhibitor, consistently and significantly inhibited GnT-III expression and its products. Conversely, the inhibition of β-catenin translocation into the nuclei increased GnT-III activation. Taken together, the results of the present study are the first to clearly demonstrate that GnT-III expression may be precisely regulated by the interplay of E-cadherin-catenin complex-mediated cell-cell adhesion and Wnt/β-catenin signaling, which are both crucial in the process of epithelial-mesenchymal transitions in physiological and pathological conditions.
Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai Miyagi 981-8558, Japan.
Qingsong
Q
Xu
Ryota
R
Akama
Tomoya
T
Isaji
Yingying
Y
Lu
Hirokazu
H
Hashimoto
Yoshinobu
Y
Kariya
Tomohiko
T
Fukuda
Yuguang
Y
Du
Jianguo
J
Gu
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology*; D004789:Enzyme Activation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006801:Humans; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000096:biosynthesis*; D015398:Signal Transduction / Q000502:physiology*; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
D015820:Cadherins; D019012:Integrin beta1; C555510:WNT3A protein, human; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D051176:beta Catenin; D017351:N-Acetylglucosaminyltransferases; C054599:beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase