title: TGF-β sensitivity is determined by N-linked glycosylation of the type II TGF-β receptor.
abstract: N-linked glycosylation is a critical determinant of protein structure and function, regulating processes such as protein folding, stability and localization, ligand-receptor binding and intracellular signalling. TβRII [type II TGF-β (transforming growth factor β) receptor] plays a crucial role in the TGF-β signalling pathway. Although N-linked glycosylation of TβRII was first demonstrated over a decade ago, it was unclear how this modification influenced TβRII biology. In the present study, we show that inhibiting the N-linked glycosylation process successfully hinders binding of TGF-β1 to TβRII and subsequently renders cells resistant to TGF-β signalling. The lung cancer cell line A549, the gastric carcinoma cell line MKN1 and the immortal cell line HEK (human embryonic kidney)-293 exhibit reduced TGF-β signalling when either treated with two inhibitors, including tunicamycin (a potent N-linked glycosylation inhibitor) and kifunensine [an inhibitor of ER (endoplasmic reticulum) and Golgi mannosidase I family members], or introduced with a non-glycosylated mutant version of TβRII. We demonstrate that defective N-linked glycosylation prevents TβRII proteins from being transported to the cell surface. Moreover, we clearly show that not only the complex type, but also a high-mannose type, of TβRII can be localized on the cell surface. Collectively, these findings demonstrate that N-linked glycosylation is essentially required for the successful cell surface transportation of TβRII, suggesting a novel mechanism by which the TGF-β sensitivity can be regulated by N-linked glycosylation levels of TβRII.
authors.affiliation: CHA Cancer Research Institute, CHA University, Seoul, 135-081, South Korea.
authors.forename: Young-Woong
authors.initials: YW
authors.lastname: Kim
authors.forename: Jinah
authors.initials: J
authors.lastname: Park
authors.forename: Hyun-Ju
authors.initials: HJ
authors.lastname: Lee
authors.forename: So-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Seong-Jin
authors.initials: SJ
authors.lastname: Kim
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001216:Asparagine / Q000737:chemistry; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence; D006031:Glycosylation / Q000187:drug effects; D057809:HEK293 Cells; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C065629:kifunensine; D014415:Tunicamycin; D001216:Asparagine; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II