Effects of inactivation-resistant agonists on the signalling, desensitization and down-regulation of bradykinin B(2) receptors.
OBJECTIVE
A peptide bradykinin (BK) B(2) receptor agonist partially resistant to degradation, B-9972, down-regulates this receptor subtype. We have used another recently described non-peptide agonist, compound 47a, as a tool to study further the effects of metabolically more stable and thus persistent, agonists of the BK B(2) receptor on signalling, desensitization and down-regulation of this receptor.


RESULTS
Compound 47a was a partial agonist at the B(2) receptor in the human umbilical vein, where it shared with B-9972 a very slow relaxation on washout, and in HEK 293 cell lines expressing tagged forms [myc, green fluorescent protein (GFP)] of the rabbit B(2) receptor. Compound 47a desensitized the umbilical vein to BK. In the cellular systems, the inactivation-resistant agonists induced [Ca(2+)](i) transients as brief as those of BK but affected other functions with a longer duration than BK [12 h; receptor endocytosis, endosomal beta-arrestin(1/2) translocation, protein kinase C-dependent extracellular signal-regulated kinases (ERK)1/2 phosphorylation and c-Fos expression]. The B(2) receptor-GFP was degraded in cells exposed to B-9972 or compound 47a for 12 h. The non-peptide B(2) receptor antagonist LF 16-0687 prevented all effects of compound 47a, which were also absent in cells lacking recombinant B(2) receptors.


CONCLUSIONS
Inactivation-resistant agonists revealed a long-lasting assembly of the agonist-B(2) receptor-beta-arrestin complexes in endosomal structures and induce 'biased signalling' (in terms of activation of ERK and c-Fos) as a function of time. Further, B-9972 and compound 47a, unlike BK, efficiently down-regulated BK B(2) receptors.
Bawolak
Marie-Thérèse
MT
Centre de recherche en rhumatologie et immunologie, Centre Hospitalier Universitaire de Québec and Department of Medicine, Université Laval, Québec, QC, Canada.
Fortin
Sébastien
S
Bouthillier
Johanne
J
Adam
Albert
A
Gera
Lajos
L
C-Gaudreault
René
R
Marceau
François
F
D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D001562:Benzimidazoles / Q000494:pharmacology*; D001667:Binding, Competitive; D065094:Bradykinin B2 Receptor Antagonists; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D015536:Down-Regulation; D006801:Humans; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D011817:Rabbits; D011869:Radioligand Assay; D043782:Receptor, Bradykinin B2 / Q000819:agonists* / Q000502:physiology*; D011994:Recombinant Proteins / Q000819:agonists / Q000037:antagonists & inhibitors; D015398:Signal Transduction; D014471:Umbilical Veins / Q000187:drug effects / Q000378:metabolism; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins
C000605253:ARRB1 protein, human; D000631:Aminopyridines; D019390:Arrestins; C506335:B9972; D001562:Benzimidazoles; D065094:Bradykinin B2 Receptor Antagonists; C403051:LF 16-0687; D009842:Oligopeptides; D011804:Quinolines; D043782:Receptor, Bradykinin B2; D011994:Recombinant Proteins; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins; D002118:Calcium