Protein kinase C inhibitors enhance G‐protein induced phospholipase A<sub>2</sub> activation in intact human platelets

Iorio, Paolo; Gresele, Paolo; Stasi, Mario; Nucciarelli, Fabio; Vezza, Roberta; Nenci, Giuseppe G.; Goracci, G

doi:10.1016/0014-5793(96)00117-2

Cited by 24 publications

(16 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Platelets were pelleted in the presence of 0.2 WM PGI 2 and 50 U/ml heparin and then resuspended in Tyrode's bu¡er containing 0.35% BSA, apyrase (20 Wg/ml) and PGI 2 (0.2 WM). This procedure was repeated twice to obtain washed platelets (WP) which were ¢nally resuspended, unless di¡erently indicated, in Tyrode's bu¡er containing 0.35% BSA without addition of Ca 2 and Mg 2 (standard Tyrode's bu¡er) [6].…”

Section: Preparation Of Human Plateletsmentioning

confidence: 99%

“…Washed labelled platelets (WLP) were prepared as previously reported [6]. Brie£y, resuspended platelets were incubated with [ 3 H]AA (1 WCi/ml of platelet suspension) at 37³C for 1 h. Further washes removed the excess of labelled precursor.…”

Section: Preparation Of Platelets Labelled With [ 3 H]arachidonic Acidmentioning

confidence: 99%

“…Platelet aggregation was monitored by photometry (Aggrecorder, Menarini, Milan, Italy). Lipid extraction, AA isolation and determination of radioactivity were performed as previously described [6].…”

Section: Preparation Of Platelets Labelled With [ 3 H]arachidonic Acidmentioning

confidence: 99%

“…Our laboratory has recently reported that PKC inhibitors do not a¡ect the release of AA in thrombin-stimulated human platelets but, surprisingly, they increase that induced by the stimulation with £uoroaluminate (AlF 3 4 ), an unspeci¢c and widely used G-protein activator [6]. This ¢nding suggests that, in intact human platelets, G-protein-induced liberation of arachidonic acid may take place by an unknown mechanism that is down-regulated by PKC.…”

Section: Introductionmentioning

confidence: 99%

“…[5,6,8,9,11,12,14, H]Arachidonic acid ([ 3 H]AA; 191^220 Ci/ mmol) was purchased from NEN Research Products (Boston, MA, USA). [9,10(N)-3 H]Oleic acid was from Amersham Pharmacia Biotech (Essex, UK).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Evidence that cytosolic phospholipase A₂ is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate

et al. 1999

Self Cite

View full text Add to dashboard Cite

We reported that protein kinase C (PKC) inhibitors increase the release of arachidonic acid induced by fluoroaluminate (AlF 3 4 ), an unspecific G-protein activator, in intact human platelets. Now we demonstrate that this effect is independent of the extracellular Ca 2+ concentration and that AlF 3 4 -induced release of AA is abolished by BAPTA, an intracellular Ca 2+ chelator, even in the presence of GF 109203X, a specific and potent PKC inhibitor. This compound also blocks the liberation of the secretory phospholipase A 2 in the extracellular medium, indicating that this enzyme is not involved in the potentiation of arachidonic acid by PKC inhibitors. On the other hand, the latter effect is completely abolished by treatment of platelets with AACOCF 3 , a specific inhibitor of cytosolic phospholipase A 2 (cPLA 2 ). These observations indicate that cPLA 2 is responsible for the AlF 3 4 -induced release of arachidonic acid by a mechanism that is down-regulated by PKC.z 1999 Federation of European Biochemical Societies.

show abstract

Section: Preparation Of Human Plateletsmentioning

confidence: 99%

Section: Preparation Of Platelets Labelled With [ 3 H]arachidonic Acidmentioning

confidence: 99%

Section: Preparation Of Platelets Labelled With [ 3 H]arachidonic Acidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Evidence that cytosolic phospholipase A₂ is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate

et al. 1999

Self Cite

View full text Add to dashboard Cite

show abstract

24,25-(OH)2D3 regulates protein kinase C through two distinct phospholipid-dependent mechanisms

et al. 1996

View full text Add to dashboard Cite

We have previously shown that 24,25-(OH)2D3 plays a major role in resting zone (RC) chondrocyte differentiation and that this vitamin D metabolite regulates protein kinase C (PKC). The aim of the present study was to identify the signal transduction pathway used by 24,25-(OH)2D3 to stimulate PKC activation. Confluent, fourth passage RC cells from rat costochondral cartilage were used to evaluate the mechanism of PKC activation. Treatment of RC cultures with 24,25-(OH)2D3 for 90 min produced a dose-dependent increase in diacylglycerol (DAG). Addition of R59022, a diacylglycerol kinase inhibitor, significantly increased PKC activity in cultures treated with 24,25-(OH)2D3. Addition of dioctanoylglycerol (DOG) to plasma membranes isolated from RC increased PKC activity 447-fold. Addition of pertussis toxin or cholera toxin to control cultures elevated basal PKC activity. When added together with 10(-9) M 24,25-(OH)2D3, there was an additive effect on PKC activity but in cultures treated with 10(-8) M 24,25-(OH)2D3, only the hormone-dependent stimulation of PKC was observed. The phospholipase C inhibitor, U73-122, had no effect on PKC activity, indicating that the DAG produced in response to 24,25-(OH)2D3 is not derived from phosphatidylinositol. Addition of the tyrosine kinase inhibitor, genistein, also had no effect on 24,25-(OH)2D3-stimulated PKC, further supporting the hypothesis that phospholipase C is not involved in the mechanism and that phospholipase D is responsible for the increase in DAG production. Phospholipase A2 inhibitors, quinacrine and AACOCF3, and the cyclooxygenase inhibitor indomethacin increased PKC activity in the RC cultures. Exogenous PGE2, one of the downstream products of phospholipase A2 action, inhibited PKC activity. These results suggest that 24,25-(OH)2D3 regulates PKC activity by two distinct phospholipid-dependent mechanisms: production of DAG via phospholipase D and inhibition of the production of PGE2 via inhibition of phospholipase A2 and cyclooxygenase.

show abstract

Alteration of thrombine‐signaling mechanism by heptachlor in human platelets

Juri

Potas

D’Angelo

2002

J Biochem & Molecular Tox

View full text Add to dashboard Cite

Heptachlor is a persistent organochlorine insecticide that has been detected in human tissues and fluids. The ability of heptachlor to interfere with platelet phosphoinositides metabolism and related signaling events stimulated by thrombin was evaluated. In vitro incubations with a concentration range of 1-100 microM heptachlor, prior to platelets activation, were performed. Experiments showed that 10 microM increased protein Kinase C (PKC) activity and phosphatidylinositolbiphosphate and phosphatidic acid phosphorylation. Simultaneously phosphatidylcholine and phosphatidylethanolamine breakdown were prevented. Similar effects were observed with HC 1 microM. However, heptachlor 100 microM increased phosphatidylinositolbiphosphate phosphorylation but reduced serine/threonine kinases activity. We propose that signal transduction steps downstream phospholipase C (PLC) are unphysiologically activated by heptachlor and facilitated by the increase in phosphatidylinositolbiphosphate, the substrate for PLC activity, thus producing an accumulation of phosphatidic acid. The elevated level of this compound itself or the transient increase in diacylglycerol produced may cause calcium mobilization and the activation of PKC. In contrast with the alterations observed in phospholipids and protein phosphorylation, no changes in aggregation properties were observed.

show abstract

Protein kinase C inhibitors enhance G‐protein induced phospholipase A₂ activation in intact human platelets

Cited by 24 publications

References 21 publications

Evidence that cytosolic phospholipase A₂ is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate

Evidence that cytosolic phospholipase A₂ is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate

24,25-(OH)2D3 regulates protein kinase C through two distinct phospholipid-dependent mechanisms

Alteration of thrombine‐signaling mechanism by heptachlor in human platelets

Contact Info

Product

Resources

About

Protein kinase C inhibitors enhance G‐protein induced phospholipase A2 activation in intact human platelets

Cited by 24 publications

References 21 publications

Evidence that cytosolic phospholipase A2 is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate

Evidence that cytosolic phospholipase A2 is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate

24,25-(OH)2D3 regulates protein kinase C through two distinct phospholipid-dependent mechanisms

Alteration of thrombine‐signaling mechanism by heptachlor in human platelets

Contact Info

Product

Resources

About

Protein kinase C inhibitors enhance G‐protein induced phospholipase A₂ activation in intact human platelets

Evidence that cytosolic phospholipase A₂ is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate

Evidence that cytosolic phospholipase A₂ is down‐regulated by protein kinase C in intact human platelets stimulated with fluoroaluminate