12‐<i>O</i>‐Tetradecanoylphorbol 13‐acetate stimulates inositol lipid phosphorylation in intact human platelets

Courcelles, D. de Chaffoy de; Roevens, Peter; Belle, H. Van

doi:10.1016/0014-5793(84)80811-x

Cited by 99 publications

(17 citation statements)

References 25 publications

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“…(11,13) and Halenda and Feinstein (12), we have observed that phorbol esters and 1,2-diacyiglycerols rapidly increase the levels of polyphosphoinositides in platelets. The mechanism of this action is not known, but a role for protein kinase C is indicat- ed as both of these agents activate this enzyme in the same concentrations that raise the levels of the polyphosphoinositides (12).…”

Section: Discussionsupporting

confidence: 57%

“…In the present study, we have observed that maximal 32p phosphorylation of the 40,000-dalton protein by PBt2 (200 nM) is reached after 1 min and is maintained for at least 10 min (not shown). In contrast, de Chaffoy de Courcelles et al (11) reported that phosphorylation of the 40,000-dalton protein by OAG (10 ,uM) returns to basal levels within 4 min in human platelets.…”

mentioning

confidence: 87%

“…Recently, it has been demonstrated that phorbol 12-myristate 13-acetate (11,12) and 1-oleoyl-2-acetyl-glycerol (OAG) (13) stimulate a rapid increase in the levels of [3 P]phosphatidylinositol 4-phosphate and [32P]phosphatidylinositol 4,5-bisphosphate in platelets. Moreover, Halenda and Feinstein (12) further showed that the increased incorporation of 32p into these two lipids was accompanied by an increase in their mass.…”

mentioning

confidence: 99%

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1,2-Diacylglycerol and phorbol ester inhibit agonist-induced formation of inositol phosphates in human platelets: possible implications for negative feedback regulation of inositol phospholipid hydrolysis.

Watson¹,

Lapetina²

1985

Proc. Natl. Acad. Sci. U.S.A.

186

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The present study has demonstrated that pretreatment of human platelets with either phorbol ester or 1,2-diacylglycerol inhibits agonist-induced formation of inositol phosphates; this inhibition can be correlated with a decrease in the release of ATP and 5-hydroxytryptamine by thrombin. The mechanism of this action is not known, but a role for protein kinase C is suggested, as both phorbol ester and 1,2-diacylglycerol have in common the ability to activate this enzyme. These results have important implications as a possible negative feedback control over agonist-induced hydrolysis of inositol phospholipids.Platelet activation by agonists such as thrombin (1-3) and collagen (4) is mediated through the phosphodiesteric cleavage of polyphosphoinositides and, possibly, phosphatidylinositol. This hydrolysis generates two bioactive products, 1,2-diacylglycerol and inositol 1,4,5-trisphosphate (InsP3). 1,2-Diacylglycerol activates protein kinase C, and this has been shown to phosphorylate a 40,000-dalton protein in platelets of unknown function (5); phorbol esters can substitute for 1,2-diacylglycerol in the activation of protein kinase C (5). InsP3 mobilizes Ca2' from the endoplasmic reticulum of a number of tissues (6-9) and induces protein phosphorylation in platelets (10).Recently, it has been demonstrated that phorbol 12-myristate 13-acetate (11, 12) and 1-oleoyl-2-acetyl-glycerol (OAG) (13) (refs. 3, 14, and 15, re-spectively). The platelets were finally suspended at a concentration of 8 x 108 per ml in a modified Tyrode Hepes buffer (134 mM NaCl/12 mM NaHCO3/2.9 mM KCl/0.36 mM NaH2PO4/1 mM MgCl2/5 mM Hepes/5 mM glucose/1 mM EGTA, pH 7.4). Samples (0.49 ml) were placed in aggregometer tubes and left at 370C for 3 min. OAG and phorbol dibutyrate (PBt2) were added and the tubes were left without stirring at 370C for various times. [Similar results were obtained when platelets were stirred in a Chrono-Log (Havertown, PA) aggregometer.] The reaction was stopped by transferring the contents to tubes containing 1.88 ml of CHCl3/MeOH/HCl (100:200:2) by means of a Pasteur pipette. Inositol phosphates were analyzed by ion exchange chromatography, and inositol phospholipids were analyzed by thin-layer chromatography as described (3). For determinations of protein phosphorylation, however, the reaction was stopped by transferring aliquots (100 ul) to tubes containing 25 ,1l of 5 times concentrated Laemmli sample buffer and incubated at 100°C for 10 min; proteins were then analyzed as described (14).Experiments involving the pretreatment of platelets with PBt2 or OAG before addition of thrombin were carried out in the following manner. Platelets (0.49 ml) were incubated with OAG (50 ,uM) or PBt2 (200 nM) in aggregometer tubes for 9 min at 37°C without stirring. They/ were then transferred to a Chrono-Log aggregometer and, stirred for 1 min at 37°C. Thrombin, collagen, or platelet-activating factor was then added and the reaction was terminated at various times by transferring to CHCl3/MeOH/HCl (100:200:2) as descri...

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Section: Discussionsupporting

confidence: 57%

mentioning

confidence: 87%

mentioning

confidence: 99%

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1,2-Diacylglycerol and phorbol ester inhibit agonist-induced formation of inositol phosphates in human platelets: possible implications for negative feedback regulation of inositol phospholipid hydrolysis.

Watson¹,

Lapetina²

1985

Proc. Natl. Acad. Sci. U.S.A.

186

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“…Whilst fMetLeuPhe increases the level of PI-P and PI-Pz, PMA appears only to increase the phosphorylation of PI to PI-P. The ability of PMA to increase the levels of the PPI has been reported for platelets [20] and lymphocytes [21] and may be indicative of protein kinase C involvement in the activation of inositol lipid kinases.…”

Section: Discussionmentioning

confidence: 80%

Breakdown and synthesis of polyphosphoinositides in fMetLeuPhe‐stimulated neutrophils

1985

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The interconversions of the inositoi-containing lipids (PI, PI-P and PI-P3 and their products (DG, inositol phosphates and PA) in human and rabbit neutrophils stimulated with fMetLeuPhe and PMA have been examined. PMA causes only the phosphorylation of PI to PI-P whereas fMetLeuPhe causes phosphorylation of both PI and PI-P yielding PI-P, and the hydrolysis of all three lipids. While the predominant reaction is breakdown of PI to PA catalysed by phospholipase D, approx. 2% of PI is converted to polyphosphoinositides and then broken down by the phospholipase C route yielding inositol phosphates and DG. The latter reaction occurs without detectable lag and is a function of receptor occupancy. The amount of inositol trisphosphate thus formed would be sufficient to release Caz+ from intracellular stores.Neutrophii Receptor Pol_vphosphoinositide Inositolphosphate Phospholipase D DiacylglycerolPhospholipase C

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“…In contrast to OAG, PMA inhibited both calcium release and influx for at least 20 min. This probably results from slow PMA metabolism which would lead to persistent activation of protein kinase [16].…”

Section: Modulation Of Paf Bindingmentioning

confidence: 99%

Modulation of platelet-activating-factor-induced calcium influx and intracellular calcium release in platelets by phorbol esters

Valone

Johnson

1987

Biochemical Journal

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The mechanisms by which platelet-activating factor (PAF) and thrombin increase intracellular calcium were examined. Platelets were loaded with the calcium-sensitive fluorescent probe Quin 2 and then were suspended in buffer containing 0.5 mM-Mn2" in order to quantify simultaneously calcium release from intracellular stores and divalent cation influx. Pretreating platelets with agents which activate protein kinase C [the phorbol ester phorbol myristate acetate (PMA) or the diacylglycerol l-oleoyl-2-acetylglycerol (OAG)] inhibited increased intracellular calcium by PAF and thrombin in a dose-related manner. That protein kinase C regulates intracellular calcium by phosphorylating proteins in two distinct pathways was suggested by two observations. PAF-induced calcium release was more sensitive to inhibition by PMA and OAG than was manganese influx and the kinetics of recovery from inhibition were different for the two pathways. Both PMA and OAG aggregated Quin 2-loaded platelets without eliciting measurable increases in intracellular calcium. In contrast, prostacyclin, which increases intracellular cyclic AMP, inhibited calcium release and influx in parallel, suggesting that this agent acts at a step common to both pathways.

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12‐O‐Tetradecanoylphorbol 13‐acetate stimulates inositol lipid phosphorylation in intact human platelets

Cited by 99 publications

References 25 publications

1,2-Diacylglycerol and phorbol ester inhibit agonist-induced formation of inositol phosphates in human platelets: possible implications for negative feedback regulation of inositol phospholipid hydrolysis.

1,2-Diacylglycerol and phorbol ester inhibit agonist-induced formation of inositol phosphates in human platelets: possible implications for negative feedback regulation of inositol phospholipid hydrolysis.

Breakdown and synthesis of polyphosphoinositides in fMetLeuPhe‐stimulated neutrophils

Modulation of platelet-activating-factor-induced calcium influx and intracellular calcium release in platelets by phorbol esters

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