Site-specific O-Glycosylation by Polypeptide N-Acetylgalactosaminyltransferase 2 (GalNAc-transferase T2) Co-regulates β1-Adrenergic Receptor N-terminal Cleavage
| Autor: | Henrik Clausen, Jarkko J. Lackman, Hamayun Khan, Christopher M. Overall, Ulla E. Petäjä-Repo, Yoshiki Narimatsu, Hanna E. Tuhkanen, Lasse H Hansen, Katrine T. Schjoldager, Christoffer K. Goth, Shengjun Wang |
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| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
chemistry.chemical_classification Agonist Cleavage factor Cleavage stimulation factor Adrenergic receptor medicine.drug_class Cell Biology Cleavage and polyadenylation specificity factor Biochemistry Cell biology carbohydrates (lipids) 03 medical and health sciences 030104 developmental biology chemistry medicine lipids (amino acids peptides and proteins) Glycoprotein Receptor Molecular Biology G protein-coupled receptor |
| Zdroj: | Journal of Biological Chemistry. 292:4714-4726 |
| ISSN: | 0021-9258 |
| Popis: | The β1-adrenergic receptor (β1AR) is a G protein-coupled receptor (GPCR) and the predominant adrenergic receptor subtype in the heart, where it mediates cardiac contractility and the force of contraction. Although it is the most important target for β-adrenergic antagonists, such as β-blockers, relatively little is yet known about its regulation. We have shown previously that β1AR undergoes constitutive and regulated N-terminal cleavage participating in receptor down-regulation and, moreover, that the receptor is modified by O-glycosylation. Here we demonstrate that the polypeptide GalNAc-transferase 2 (GalNAc-T2) specifically O-glycosylates β1AR at five residues in the extracellular N terminus, including the Ser-49 residue at the location of the common S49G single-nucleotide polymorphism. Using in vitro O-glycosylation and proteolytic cleavage assays, a cell line deficient in O-glycosylation, GalNAc-T-edited cell line model systems, and a GalNAc-T2 knock-out rat model, we show that GalNAc-T2 co-regulates the metalloproteinase-mediated limited proteolysis of β1AR. Furthermore, we demonstrate that impaired O-glycosylation and enhanced proteolysis lead to attenuated receptor signaling, because the maximal response elicited by the βAR agonist isoproterenol and its potency in a cAMP accumulation assay were decreased in HEK293 cells lacking GalNAc-T2. Our findings reveal, for the first time, a GPCR as a target for co-regulatory functions of site-specific O-glycosylation mediated by a unique GalNAc-T isoform. The results provide a new level of β1AR regulation that may open up possibilities for new therapeutic strategies for cardiovascular diseases. |
| Databáze: | OpenAIRE |
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