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PKC‐mediated inhibitory feedback of the cholecystokinin 1 receptor controls the shape of oscillatory Ca 2+ signals
Author(s) -
Willems Peter H. G. M.,
Pahle Jürgen,
Stalpers Xenia L.,
Mugahid Douaa,
Nikolaew Alexander,
Koopman Werner J. H.,
Kummer Ursula
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13267
Subject(s) - cholecystokinin , chinese hamster ovary cell , extracellular , bursting , phosphorylation , receptor , agonist , cholecystokinin receptor , protein kinase c , microbiology and biotechnology , biology , signal transduction , biophysics , chemistry , endocrinology , medicine , biochemistry , neuroscience
Translation of extracellular hormonal input into cellular responses is often mediated by repetitive increases in cytosolic free Ca 2+ concentration ([Ca 2+ ] c ). Amplitude, duration and frequency of these so‐called [Ca 2+ ] c oscillations then carry information about the nature and concentration of the extracellular signalling molecule. At present, there are different hypotheses concerning the induction and control of these oscillations. Here, we investigated the role of agonist‐induced receptor phosphorylation in this process using Chinese hamster ovary cells stably expressing a variant of the cholecystokinin 1 receptor ( CCK 1R) lacking the four consensus sites for protein kinase C ( PKC ) phosphorylation and deficient in CCK ‐induced receptor phosphorylation ( CCK 1R‐mt cells). In the presence of cholecystokinin‐(26‐33)‐peptide amide ( CCK ‐8), these cells displayed Ca 2+ oscillations with a much more pronounced bursting dynamics rather than the dominant spiking dynamics observed in Chinese hamster ovary cells stably expressing the wild‐type CCK 1R. The bursting behaviour returned to predominantly spiking behaviour following removal of extracellular Ca 2+ , suggesting that CCK ‐8‐induced, PKC ‐mediated CCK 1R phosphorylation inhibits Ca 2+ influx across the plasma membrane. To gain mechanistic insight into the underlying mechanism we developed a mathematical model able to reproduce the experimental observations. From the model we conclude that binding of CCK ‐8 to the CCK 1R leads to activation of PKC which subsequently phosphorylates the receptor to inhibit the receptor‐mediated influx of Ca 2+ across the plasma membrane. Receptor‐specific differences in this feedback mechanism may, at least in part, explain the observation that different agonists evoke [Ca 2+ ] c oscillations with different kinetics in the same cell type.