N-acetylglucosaminyltransferase V expression levels regulate cadherin-associated homotypic cell-cell adhesion and intracellular signaling pathways.
A common glycan alteration in transformed cells and human tumors is the highly elevated levels of N-linked beta(1,6)glycans caused by increased transcription of N-acetylglucosaminyltransferase V (GnT-V). Here, we define the involvement of GnT-V in modulation of homotypic cell-cell adhesion in human fibrosarcoma HT1080 and mouse NIH3T3 cells. Increased GnT-V expression resulted in a significant decrease in the rates of calcium-dependent cell-cell adhesion. Reduced cell-cell adhesion was blocked by function-blocking antibody against N-cadherin and abrogated by pre-treatment of cells with swainsonine, demonstrating the involvement of N-cadherin in the cell-cell adhesion and that changes in N-linked beta(1,6)glycan expression are responsible for the reduction in rates of adhesion, although this reduction could be mediated by the altered N-linked glycosylation of glycoproteins other than N-cadherin. Overexpression of GnT-V had no effect on the levels of cell surface expression of N-cadherin; however, it did cause a marked enhancement of both beta(1,6) branching and poly-N-acetyllactosamine expression on N-cadherin. GnT-V overexpression resulted in decreased N-cadherin clustering on the cell surface induced by anti-N-cadherin antibody and affected the outside-in signal transduction pathway of ERK mediated by N-cadherin. Overexpression of GnT-V sensitized stimulation of tyrosine phosphorylation of catenins by growth factors and expression of v-src, which is consistent with its reduction of cell-cell adhesion. In vitro, GnT-V-overexpressing cells showed increased motility concomitant with increased phosphorylation of catenins. Moreover, GnT-V-deficient embryo fibroblasts from GnT-V homozygous null mice (GnT-V(-/-)) express N-cadherin and showed significantly increased levels of N-cadherin-based cell-cell adhesion compared with those from GnT-V(+/-) mice. These levels of adhesion were inhibited significantly by transient expression of GnT-V, confirming the hypothesis that levels of GnT-V can regulate cadherin-associated homotypic cell-cell adhesion. Aberrant N-linked beta(1,6) branching that occurs during oncogenesis can, therefore, lessen cell-cell adhesion, contributing to increased cellular motility and invasiveness.
Guo
Hua-Bei
HB
Department of Biochemistry and Molecular Biology and Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA.
Lee
Intaek
I
Kamar
Maria
M
Pierce
Michael
M
D000818:Animals; D019921:Biotinylation; D015820:Cadherins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D006133:Growth Substances; D006720:Homozygote; D006801:Humans; D015151:Immunoblotting; D037102:Lectins / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000096:biosynthesis*; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D011233:Precipitin Tests; D015398:Signal Transduction; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
D015820:Cadherins; D006133:Growth Substances; D037102:Lectins; D014443:Tyrosine; D017351:N-Acetylglucosaminyltransferases; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium