TY - JOUR
T1 - Regulation of ovarian ornithine decarboxylase. Role of calcium ions in enzyme induction in isolated swine granulosa cells in vitro
AU - Veldhuis, Johannes D.
N1 - Funding Information:
The author gratefully acknowledges the technical assistance of Eileen Wolck and Patricia Klase in the conduct of this work. Marlene Thompson and Pat Hoy prepared the manuscript. This work was supported by National Research Service Award No. F32-HD-05775 from the National Institute of Child Health and Human Development, NIH, Bethesda, ND, U.S.A.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1982/4/29
Y1 - 1982/4/29
N2 - When swine granulosa cells were cultured in chemically defined medium selectively deficient in Ca2+, the dose-dependent stimulation of ornithine decarboxylase (EC 4.1.1.17) activity in response to prostaglandin E2, l-epinephrine or the somatomedin, multiplication-stimulating activity, was attenuated markedly. Putative calcium influx blockers, verapamil and diltiazem, also inhibited hormone-stimulated enzymic activity. Similar inhibitory effects were exerted by divalent (cobalt) or trivalent (lanthanum) cations believed to compete with calcium for extracellular binding sites. The suppressive effects of extracellular calcium deprivation were time-dependent (suggesting gradual depletion of intracellular calcium stores), and could be mimicked by the intracellular antagonist of calcium action, trifluoperazine. The mechanism(s) subserving diminished hormonal induction of enzyme activity could not be accounted for by alterations in cell viability, general protein synthesis, half-life of decay of enzyme activity (measured in the presence of cycloheximide), or apparent Km of ornithine decarboxylase. Ca2+ and/or calcium antagonists did not modify enzyme activity in cell-free preparations. These observations implicate Ca2+ in the hormonal induction of a discrete cytosolic enzyme in isolated intact ovarian cells.
AB - When swine granulosa cells were cultured in chemically defined medium selectively deficient in Ca2+, the dose-dependent stimulation of ornithine decarboxylase (EC 4.1.1.17) activity in response to prostaglandin E2, l-epinephrine or the somatomedin, multiplication-stimulating activity, was attenuated markedly. Putative calcium influx blockers, verapamil and diltiazem, also inhibited hormone-stimulated enzymic activity. Similar inhibitory effects were exerted by divalent (cobalt) or trivalent (lanthanum) cations believed to compete with calcium for extracellular binding sites. The suppressive effects of extracellular calcium deprivation were time-dependent (suggesting gradual depletion of intracellular calcium stores), and could be mimicked by the intracellular antagonist of calcium action, trifluoperazine. The mechanism(s) subserving diminished hormonal induction of enzyme activity could not be accounted for by alterations in cell viability, general protein synthesis, half-life of decay of enzyme activity (measured in the presence of cycloheximide), or apparent Km of ornithine decarboxylase. Ca2+ and/or calcium antagonists did not modify enzyme activity in cell-free preparations. These observations implicate Ca2+ in the hormonal induction of a discrete cytosolic enzyme in isolated intact ovarian cells.
KW - (Swine granulosa cell)
KW - Ca
KW - Enzyme induction
KW - Ornithine decarboxylase
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U2 - 10.1016/0167-4889(82)90014-3
DO - 10.1016/0167-4889(82)90014-3
M3 - Article
C2 - 6952940
AN - SCOPUS:0020493185
SN - 0167-4889
VL - 720
SP - 211
EP - 216
JO - BBA - Molecular Cell Research
JF - BBA - Molecular Cell Research
IS - 2
ER -