Site-specific
| Autor: | Christoffer K, Goth, Hanna E, Tuhkanen, Hamayun, Khan, Jarkko J, Lackman, Shengjun, Wang, Yoshiki, Narimatsu, Lasse H, Hansen, Christopher M, Overall, Henrik, Clausen, Katrine T, Schjoldager, Ulla E, Petäjä-Repo |
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| Rok vydání: | 2016 |
| Předmět: |
Glycosylation
Hep G2 Cells Cell Biology Polymorphism Single Nucleotide Rats carbohydrates (lipids) Gene Knockout Techniques HEK293 Cells Proteolysis Animals Humans N-Acetylgalactosaminyltransferases Protein Isoforms lipids (amino acids peptides and proteins) Amino Acid Sequence Receptors Adrenergic beta-1 |
| Zdroj: | The Journal of biological chemistry. 292(11) |
| ISSN: | 1083-351X |
| 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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