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Title: Phorbol ester stimulates membrane association of protein kinase C and inhibits spontaneous Ca/sup 2 +/ dependent sarcoplasmic reticulum Ca/sup 2 +/ release in rat cardiac cells

Abstract

Spontaneous oscillatory Ca/sup 2 +/ release from sarcoplasmic reticulum (SR) occurs in rat cardiac myocytes at hyperpolarized membrane potentials and is manifested as contractile waves (W). W frequency varies with SR functional status and cell Ca/sup 2 +/ loading. In myocyte suspensions (Hepes buffer, 37/sup 0/C (Ca/sup 2 +/) = 1.0mM) phorbol myristate acetate, PMA, (10/sup -7/ M) increased protein kinase C activity in membranes as a fraction of total (PKCAM) fivefold with a t 1/2 of < 30 sec (n = 3) and decreased W frequency in individual myocytes (n = 8). This effect varied directly and linearly with baseline W frequency, r = .94, p < .001). Dioctanoyl glycerol (10 ..mu.. M) had a similar effect on W. The PMA effect to decrease W frequency could be a direct one on SR or result from a reduction in cell Ca/sup 2 +/. The time course of PKCAM change is sufficiently rapid for it to mediate the effect on W. Thus, enhanced PKCAM may exert negative feedback control on Ca/sup 2 +/ mobilization during ..cap alpha..-adrenergic stimulation.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Gerontology Research Center, Baltimore, MD
OSTI Identifier:
5422312
Report Number(s):
CONF-8604222-
Journal ID: CODEN: FEPRA
Resource Type:
Conference
Resource Relation:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States); Journal Volume: 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; CALCIUM; MEMBRANE TRANSPORT; PHORBOL ESTERS; BIOLOGICAL EFFECTS; PHOSPHOTRANSFERASES; ENZYME ACTIVITY; CELL MEMBRANES; HEART; RATS; ALKALINE EARTH METALS; ANIMALS; BODY; CARCINOGENS; CARDIOVASCULAR SYSTEM; CELL CONSTITUENTS; ELEMENTS; ENZYMES; ESTERS; MAMMALS; MEMBRANES; METALS; ORGANIC COMPOUNDS; ORGANS; PHOSPHORUS-GROUP TRANSFERASES; RODENTS; TRANSFERASES; VERTEBRATES 560301* -- Chemicals Metabolism & Toxicology-- Cells-- (-1987)

Citation Formats

Capogrossi, M.C., Kaku, T., Filburn, C.H., Pelto, D.J., Hansford, R.G., and Lakatta, E.G.. Phorbol ester stimulates membrane association of protein kinase C and inhibits spontaneous Ca/sup 2 +/ dependent sarcoplasmic reticulum Ca/sup 2 +/ release in rat cardiac cells. United States: N. p., 1986. Web.
Capogrossi, M.C., Kaku, T., Filburn, C.H., Pelto, D.J., Hansford, R.G., & Lakatta, E.G.. Phorbol ester stimulates membrane association of protein kinase C and inhibits spontaneous Ca/sup 2 +/ dependent sarcoplasmic reticulum Ca/sup 2 +/ release in rat cardiac cells. United States.
Capogrossi, M.C., Kaku, T., Filburn, C.H., Pelto, D.J., Hansford, R.G., and Lakatta, E.G.. 1986. "Phorbol ester stimulates membrane association of protein kinase C and inhibits spontaneous Ca/sup 2 +/ dependent sarcoplasmic reticulum Ca/sup 2 +/ release in rat cardiac cells". United States. doi:.
@article{osti_5422312,
title = {Phorbol ester stimulates membrane association of protein kinase C and inhibits spontaneous Ca/sup 2 +/ dependent sarcoplasmic reticulum Ca/sup 2 +/ release in rat cardiac cells},
author = {Capogrossi, M.C. and Kaku, T. and Filburn, C.H. and Pelto, D.J. and Hansford, R.G. and Lakatta, E.G.},
abstractNote = {Spontaneous oscillatory Ca/sup 2 +/ release from sarcoplasmic reticulum (SR) occurs in rat cardiac myocytes at hyperpolarized membrane potentials and is manifested as contractile waves (W). W frequency varies with SR functional status and cell Ca/sup 2 +/ loading. In myocyte suspensions (Hepes buffer, 37/sup 0/C (Ca/sup 2 +/) = 1.0mM) phorbol myristate acetate, PMA, (10/sup -7/ M) increased protein kinase C activity in membranes as a fraction of total (PKCAM) fivefold with a t 1/2 of < 30 sec (n = 3) and decreased W frequency in individual myocytes (n = 8). This effect varied directly and linearly with baseline W frequency, r = .94, p < .001). Dioctanoyl glycerol (10 ..mu.. M) had a similar effect on W. The PMA effect to decrease W frequency could be a direct one on SR or result from a reduction in cell Ca/sup 2 +/. The time course of PKCAM change is sufficiently rapid for it to mediate the effect on W. Thus, enhanced PKCAM may exert negative feedback control on Ca/sup 2 +/ mobilization during ..cap alpha..-adrenergic stimulation.},
doi = {},
journal = {Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)},
number = ,
volume = 45:3,
place = {United States},
year = 1986,
month = 3
}

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  • Partial membrane depolarization induced by increasing the KCl concentration of the medium bathing cardiac myocytes leads to an increase in cell (Ca/sup 2 +/), and accelerates the frequency of spontaneous contractile waves (W) caused by periodic sarcoplasmic reticulum (SR) Ca/sup 2 +/ release. In suspensions of myocytes bathed in 1.0mM Ca/sup 2 +/ at 37 (pH 7.4) and loaded with the fluorescent Ca/sup 2 +/ - indicator Fura-2, by incubation with 2 ..mu..M acetoxymethyl ester for 30 min, the addition of KCl to raise (K/sup +/) from 5 to 30 mM is associated with a rapid (< 10 sec) increasemore » in fluorescence, corresponding to an increased cell (Ca/sup 2 +/). Prior exposure (3 min) to 10/sup -7/ M phorbol myristate acetate (PMA) diminishes this response to 44 +/- 10% of that in control suspensions (n = 9). Under the same conditions W frequency (min/sup -1/) in individual cells in 30 mM KCl averaged 8.3 +/- 0.6. Addition of PMA abolished W within 1 min. Diacylglycerol (10 ..mu..M L..cap alpha..-1,2-dioctanoylglycerol, di C8) had a similar effect on W frequency. The thesis is that PMA attenuates cell Ca/sup 2 +/ overload and its associated potentiation of spontaneous SR Ca/sup 2 +/ oscillations. In view of the efficacy of PMA and di C8, it is suggested that the effect is mediated by protein kinase c, and it may involve an alteration in the intracellular distribution of this enzyme.« less
  • It is now recognized that phorbol esters are negative inotropic agents in mammalian heart which presumably act via stimulation of Ca2(+)-activated phospholipid-dependent protein kinase (PKC). The goal in the present study was to identify the underlying cellular processes. Digitonin-permeabilized cultured neonatal rat ventricular myocytes were used to study biochemical and functional effects of phorbol esters on cardiac sarcoplasmic reticulum (SR). These cells contracted spontaneously at 3 microM Ca2+. Beating was inhibited by 10 microM ryanodine and was insensitive to 1 microM nifedipine. Thus, beating behavior results from the phasic oscillation of Ca2+ transport by SR in this preparation. Phorbol ester,more » 12-O-tetradecanoylphorbol-13-acetate (TPA), decreased frequency by 30%, suggesting that Ca2+ transport by SR had been reduced. Whereas cAMP stimulated the rate of oxalate-supported 45Ca2+ uptake 2-fold, phorbol esters, TPA, and phorbol 12,13-dibutyrate inhibited this process by about 45%. The effects of phorbols were specific: (a) the alpha-analogues of TPA and phorbol 12,13-dibutyrate were inactive; and (b) the phorbol esters had no effect on Ca2+ transport in cells that had been depleted of PKC. TPA decreased oxalate-stimulated Ca2+ uptake over the entire range of Ca2+ concentrations, from 0.1 to 10 microM, by at least 70% without shifting the half-maximal effective Ca2+ concentration. Taken together these results indicate that the effects of phorbol ester on cardiac contraction are due to decreased Ca2+ transport by the SR and that these responses are mediated by PKC. These studies support the interpretation that the negative inotropic effects of phorbol esters are due, in part, to decreased SR function.« less
  • Very low concentrations of the detergent, deoxycholate, have been used to isolate two functionally interesting proteins from canine cardiac sarcoplasmic reticulum. These two proteins are phospholamban, a 22,000-dalton protein, specifically phosphorylated by adenosine 3':5'-monophosphate-dependent protein kinase, and the (Ca/sup 2 +/ + Mg/sup 2 +/)-ATPase, the major protein of the sarcoplasmic reticulum, responsible for the active transport of calcium. The 22,000-dalton protein is first solubilized in a very low concentration of deoxycholate (over 2 orders of magnitude lower than normally employed), and then subjected to column chromatography. After gel filtration through Sephadex G-75, the 22,000-dalton protein appears as a singlemore » band on sodium dodecyl sulfate-polyacrylamide gels. The purified protein is specifically phosphorylated by cyclic AMP-dependent protein kinase to a level of 0.15 mol of phosphate/mol of protein. The (Ca/sup 2 +/ + Mg/sup 2 +/)-ATPase is purified by first solubilizing all of the extrinsic proteins with a low concentration of deoxycholate. An increasing amount of the deoxycholate is then added to yield the purified (Ca/sup 2 +/ + Mg/sup 2 +/)-ATPase. This protein is at least 95% pure as determined by sodium dodecyl sulfate-polyacrylamide gels and has an ATP hydrolytic activity of about 1.25 ..mu..mol of Pi/mg/min. Further addition of deoxycholate to the purified enzyme enhances the enzyme's ability to hydrolyze ATP to approximately 2.5 ..mu..mol of Pi/mg/min. The isolation of the 22,000-dalton protein and the (Ca/sup 2 +/ + Mg/sup 2 +/)-ATPase will aid in understanding how these two proteins function and if they specifically interact with one another.« less
  • Very low concentrations deoxycholate (DOC) were used to isolate two proteins from canine cardiac sarcoplasmic reticulum. These two proteins are phospholamban, a 22,000 dalton protein, and the Ca/sup 2 +/ + Mg/sup 2 +/-ATPase, the major protein of the sarcoplasmic reticulum, responsible for the active transport of calcium. The 22,000 dalton protein is first solubilized in a very low concentration of DOC and then subjected to column chromatography. After molecular weight sieving on a Sephadex G-75 column, the 22,000 dalton protein appears as a purified protein on sodium dodecyl sulfate (SDS)-polyacrylamide gels. The purified protein is specifically phosphorylated by cyclicmore » AMP-dependent protein kinase. Phospholipids are still bound to the isolated protein. The Ca/sup 2 +/ + Mg/sup 2 +/-ATPase is purified by first solubilizing all the extrinsic proteins with a low concentration of DOC. An increasing amount of DOC is then added to yield the purified Ca/sup 2 +/ + Mg/sup 2 +/-ATPase. This protein is at least 95% pure. Adding additional DOC to the purified enzyme enhances the enzyme's ability to hydrolyze ATP. (ERB)« less
  • The type II{sub {beta}} regulatory subunit of cAMP-dependent protein kinase (RII{sub {beta}}) has been hypothesized to play an important role in the growth inhibition and differentiation induced by site-selective cAMP analogs in human cancer cells, but direct proof of this function has been lacking. To address this tissue, HL-60 human promyelocytic leukemia cells were exposed to RII{sub {beta}} antisense synthetic oligodeoxynucleotide, and the effects on cAMP-induced growth regulation were examined. Exposure of these cells to RII{sub {beta}} antisense oligodeoxynucleotide resulted in a decrease in cAMP analog-induced growth inhibition and differentiation without apparent effect on differentiation induced by phorbol esters. Thismore » loss in cAMP growth regulatory function correlated with a decrease in basal and induced levels of RII{sub {beta}} protein. Exposure to RII{sub {beta}} sense, RI{sub {alpha}} and RII{sub {alpha}} antisense, or irrelevant oligodeoxynucleotides had no such effect. These results show that the RII{sub {beta}} regulatory subunit of protein kinase plays a critical role in the cAMP-induced growth regulation of HL-60 leukemia cells.« less