title: Palmitoylation of human proteinase-activated receptor-2 differentially regulates receptor-triggered ERK1/2 activation, calcium signalling and endocytosis.
abstract: hPAR(2) (human proteinase-activated receptor-2) is a member of the novel family of proteolytically activated GPCRs (G-protein-coupled receptors) termed PARs (proteinase-activated receptors). Previous pharmacological studies have found that activation of hPAR(2) by mast cell tryptase can be regulated by receptor N-terminal glycosylation. In order to elucidate other post-translational modifications of hPAR(2) that can regulate function, we have explored the functional role of the intracellular cysteine residue Cys(361). We have demonstrated, using autoradiography, that Cys(361) is the primary palmitoylation site of hPAR(2). The hPAR(2)C361A mutant cell line displayed greater cell-surface expression compared with the wt (wild-type)-hPAR(2)-expressing cell line. hPAR(2)C361A also showed a decreased sensitivity and efficacy (intracellular calcium signalling) towards both trypsin and SLIGKV. In stark contrast, hPAR(2)C361A triggered greater and more prolonged ERK (extracellular-signal-regulated kinase) phosphorylation compared with that of wt-hPAR(2) possibly through Gi, since pertussis toxin inhibited the ability of this receptor to activate ERK. Finally, flow cytometry was utilized to assess the rate and extent of receptor internalization following agonist challenge. hPAR(2)C361A displayed faster internalization kinetics following trypsin activation compared with wt-hPAR(2), whereas SLIGKV had a negligible effect on internalization for either receptor. In conclusion, palmitoylation plays an important role in the regulation of PAR(2) expression, agonist sensitivity, desensitization and internalization.
authors.affiliation: Division of Cardiovascular and Respiratory Studies, Postgraduate Medical Institute, Hull York Medical School, Castle Hill Hospital, Cottingham, East Yorkshire, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Botham
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Guo
authors.forename: Yu Pei
authors.initials: YP
authors.lastname: Xiao
authors.forename: Alyn H
authors.initials: AH
authors.lastname: Morice
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Compton
authors.forename: Laura R
authors.initials: LR
authors.lastname: Sadofsky
mesh_terms: D020013:Calcium Signaling / Q000187:drug effects; D004705:Endocytosis / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D054878:Lipoylation / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D008958:Models, Molecular; D050505:Mutant Proteins / Q000378:metabolism; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D044462:Receptors, Proteinase-Activated / Q000819:agonists / Q000378:metabolism*; D014357:Trypsin / Q000494:pharmacology
chemical_list: D050505:Mutant Proteins; D044462:Receptors, Proteinase-Activated; D037342:Pertussis Toxin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D014357:Trypsin