Long-term-desensitization of prostacyclin receptors is independent of the C-terminal tail.
Persistent stimulation of the G(s) protein-coupled prostacyclin receptor (IP-R) causes its slow desensitization in a variety of cell types, a significant desensitization requiring several hours. To evaluate the role of the human IP-R C-terminus in desensitization and agonist-induced internalization, a C-terminally truncated hIP-receptor was generated. The C-terminal 68 amino acid residues were deleted by introduction of a stop codon for exchange of the original S319 codon (termed D318 mutant). Wild-type (WT) and truncated receptor were expressed in COS1 cells. Pretreatment of cells with the stable prostacyclin mimetic cicaprost (200 nM) desensitized cAMP production via WT and D318 receptors to similar extents. The cAMP response of WT and D318, respectively, was reduced by approximately 50% of maximal cAMP formation after 8 hr of continuous agonist stimulation, indicating significant long-term desensitization. Moreover, agonist-promoted sequestration of WT and D318 C-terminally tagged with green fluorescent protein was demonstrated, indicating that receptor internalization was not prevented by truncation of the C-terminus. These results demonstrated that long-term desensitization and sequestration of hIP-R did not depend on structures located in the hIP-R C-terminus.
Hasse
Andreas
A
Institut für Pharmakologie und Klinische Pharmakologie, UniversitätsKlinikum Düsseldorf, Heinrich-Heine-Universität Düsseldorf, Germany.
Nilius
Sigrid M
SM
Schrör
Karsten
K
Meyer-Kirchrath
Jutta
J
D000818:Animals; D019556:COS Cells; D000242:Cyclic AMP / Q000378:metabolism*; D011464:Epoprostenol / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000378:metabolism; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology; D014162:Transfection
D011956:Receptors, Cell Surface; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin; D012969:Sodium Fluoride; D011464:Epoprostenol; D000242:Cyclic AMP; C043867:cicaprost