CHARACTERIZATION OF PHOSPHOINOSITIDE HYDROLYSIS IN A HUMAN ENDOMETRIAL ADENOCARCINOMA CELL LINE (ISHIKAWA).
Item
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Title
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CHARACTERIZATION OF PHOSPHOINOSITIDE HYDROLYSIS IN A HUMAN ENDOMETRIAL ADENOCARCINOMA CELL LINE (ISHIKAWA).
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Identifier
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AAI8801774
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identifier
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8801774
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Creator
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WEISS, DANIEL JAY.
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Contributor
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Erlio Gurpide
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, General
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Abstract
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Addition of acetylcholine (ACh) or carbamylcholine (CCh) to suspensions of human endometrial carcinoma cells preincubated with (3H) -myoinositol promoted a rapid rise in levels of radiolabeled inositol mono- (IP1), bis- (IP2), and tris- (IP3) phosphates. The pattern of accumulation of these compounds suggests that the initial stimulated event was hydrolysis of phosphatidylinositol 4,5-bisphosphate. Levels of this phosphoinositide decreased significantly within 30 sec following exposure to CCh while no changes in the levels of phosphatidylinositol 4-monophosphate or phosphatidylinositol were observed for as long as 5 min.;Stimulation of inositol phosphate (IP) accumulation by CCh or acetylcholine (ACh) was concentration-dependent and saturable. The Hill coefficients and EC50's of the concentration-response curves for CCh and ACh indicate interaction with a single class of low-affinity receptor. The Ki for atropine inhibition of these effects identifies the receptor as muscarinic.;Both basal and CCh-stimulated levels of IP3 and IP2, as well as IP1, were increased in the presence of 10 mM LiCl. The effect on IP1 accumulation was observed under isosmotic and hyperosmolar conditions and was concentration-dependent between 1-100 mM LiCl.;Vasopressin, oxytocin, histamine, phenylephrine, and PGF2 had no apparent effect on IP levels following incubations for up to 1 hr. Estradiol, progesterone and sulfated estrogens were also without effect on IP levels during both long and short term incubations. Phorbol 12-myristate 13-acetate and phorbol 12,13-dibutyrate inhibited up to 35% of the CCh-stimulated increase in IP accumulation. Triphenylethylene antiestrogens at micromolar concentrations increased IP levels in a concentration-dependent manner but inhibited the increase stimulated by CCh. A plasma membrane perturbing effect of these compounds is suggested by a concurrent loss of ability of the cells to exclude trypan blue.;These studies demonstrate and characterize the plasma membrane signal transduction system involving phosphoinositide hydrolysis coupled to muscarinic receptors in Ishikawa cells. Several features of the transduction events not observed in similar model systems with respect to the actions of Li+ are described. Phorbol esters and triphenylethylene antiestrogens significantly altered phosphoinositide hydrolysis in Ishikawa cells. Suggestions are made concerning the possible presence and physiological role of phosphoinositide hydrolysis in human endometrium.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
