ISSN:
0730-2312
Keywords:
phospholipase C
;
inositol-1,4,5-trisphosphate
;
protein kinase C
;
protein kinase A
;
progesterone
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
We investigated the early effects (5-60 s) of progesterone (1 pM-0.1 μM) on cytosolic free calcium concentration ([Ca2+]i) and inositol 1,4,5-trisphosphate (InsP3) formation in nonluteinized and in vitro luteinized porcine granulosa cells (pGCs). Progesterone increased [Ca2+]i and InsP3 formation within 5 s in both cell types. Progesterone induced calcium mobilization from the endoplasmic reticulum via the activation of a phospholipase C linked to a pertussis-insensitive G-protein. This process was controlled by protein kinases C and A. In contrast, only nonluteinized pGCs showed a Ca2+ influx via dihydropyridine-insensitive calcium channel. In both cell types, the nuclear progesterone receptor antagonist RU-38486 did not inhibit the progesterone-induced increase in [Ca2+]i; progesterone immobilized on bovine serum albumin, which did not enter the cell, increased [Ca2+]i within 5 s and was a full agonist, but less potent than the free progesterone; pertussis toxin did not inhibit progesterone effect on InsP3. In conclusion, progesterone may interact with membrane unconventional receptors that belong to the class of membrane receptors coupled to a phospholipase C via a pertussis toxin-insensitive G-protein. The source of the Ca2+ for the progesterone-induced increase in [Ca2+]i also depends on the stage of cell luteinization. © 1996 Wiley-Liss, Inc.
Type of Medium:
Electronic Resource
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