FK506 blocks intracellular Ca2+ oscillations in bovine adrenal glomerulosa cells.
The inositol 1,4,5-trisphosphate (InsP(3)) receptor is a ligand-gated Ca(2+) channel playing an important role in the control of intracellular Ca(2+). In the study presented here, we demonstrate that angiotensin (AngII), phorbol ester (PMA), and FK506 significantly increase the level of InsP(3) receptor phosphorylation in intact bovine adrenal glomerulosa cells. With a back-phosphorylation approach, we showed that the InsP(3) receptor is a good substrate for protein kinase C (PKC) and that FK506 increases the level of PKC-mediated InsP(3) receptor phosphorylation. With a microsomal preparation from bovine adrenal cortex, we showed that PKC enhances the release of Ca(2+) induced by a submaximal dose of InsP(3). We also showed that FK506 blocks intracellular Ca(2+) oscillations in isolated adrenal glomerulosa cells by progressively increasing the intracellular Ca(2+) concentration to a high plateau level. This effect is consistent with an inhibitory role of FK506 on calcineurin dephosphorylation of the InsP(3) receptor, thus keeping the receptor in a phosphorylated, high-conductance state. Our results provide further evidence for the crucial role of the InsP(3) receptor in the regulation of intracellular Ca(2+) oscillations and show that FK506, by maintaining the phosphorylated state of the InsP(3) receptor, causes important changes in the Ca(2+) oscillatory process.
Poirier
S N
SN
Department of Pharmacology and Department of Physiology and Biophysics, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4.
Poitras
M
M
Chorvatova
A
A
Payet
M D
MD
Guillemette
G
G
D000302:Adrenal Cortex / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D065095:Calcineurin Inhibitors; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007424:Intracellular Fluid / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D016559:Tacrolimus / Q000494:pharmacology*; D015384:Zona Glomerulosa / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*
D065095:Calcineurin Inhibitors; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D002118:Calcium; D016559:Tacrolimus