Platelet-derived growth factor stimulates non-mitochondrial Ca2+ uptake and inhibits mitogen-induced Ca2+ signaling in Swiss 3T3 fibroblasts.
Changes in intracellular free Ca2+ concentration [( Ca2+]i) were used to study the interaction between mitogens in Swiss 3T3 fibroblasts. Platelet-derived growth factor (PDGF) produced an increase in [Ca2+]i and markedly decreased the increases in [Ca2+]i caused by subsequent addition of bradykinin and vasopressin. If the order of the additions was reversed the [Ca2+]i response to PDGF was not inhibited by bradykinin or vasopressin. Inhibition of protein kinase C by staurosporine or chronic treatment of the cells with phorbol 12-myristate 13-acetate prevented the inhibitory effect of PDGF on the [Ca2+]i response to vasopressin but not bradykinin. PDGF did not decrease the receptor binding of bradykinin and produced only a small decrease in the receptor binding of vasopressin. PDGF decreased the rise in [Ca2+]i caused by the Ca2+ ionophores 4-bromo-A23187 and ionomycin and by a membrane perturbing ether lipid, 1-octadecyl-2-methyl-rac-glycero-3-phosphocholine, both in the presence and absence of external Ca2+. There was no change in cell 45Ca2+ influx caused by PDGF, vasopressin, or bradykinin. 45Ca2+ efflux from cells exposed to PDGF and vasopressin mirrored the changes in [Ca2+]i caused by the agents, that is, PDGF added after vasopressin produced a further increase in 45Ca2+ efflux but vasopressin did not increase 45Ca2+ efflux after PDGF. PDGF but not vasopressin caused an increase in the uptake of 45Ca2+ into an inositol 1,4,5-trisphosphate-insensitive non-mitochondrial store in permeabilized cells. The results suggest that the decreased [Ca2+]i response to mitogens after PDGF represents an action of PDGF at a point beyond the release of intracellular Ca2+ and the influx of external Ca2+, caused by an increase in the rate of removal of cytoplasmic free Ca2+. This increased removal of cytoplasmic Ca2+ by PDGF is not due to the increased export of Ca2+ from the cell but results from increased Ca2+ uptake into non-mitochondrial stores.
Powis
G
G
Department of Pharmacology, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
Seewald
M J
MJ
Sehgal
I
I
Iaizzo
P A
PA
Olsen
R A
RA
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001920:Bradykinin / Q000494:pharmacology; D000001:Calcimycin / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D015232:Dinoprostone / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D010742:Phospholipid Ethers / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology
D000470:Alkaloids; D008934:Mitogens; D010742:Phospholipid Ethers; D010982:Platelet-Derived Growth Factor; D011994:Recombinant Proteins; D014667:Vasopressins; C026659:edelfosine; D000001:Calcimycin; D015759:Ionomycin; C033170:4-bromo-A-23187; D011493:Protein Kinase C; D019311:Staurosporine; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D001920:Bradykinin; D002118:Calcium