Protein kinase C-δ activation and tyrosine phosphorylation in platelets

AbstractSeveral protein kinase C (PKC) isoforms are expressed in human platelets. We report that PKC-δ is tyrosine phosphorylated within 30 s of platelet activation by thrombin. This correlated with a 2–3-fold increase in the kinase activity of PKC-δ relative to unstimulated platelets. The tyrosine phosphorylated PKC-δ isoform was associated with the platelet particulate (100 000×g insoluble) fraction. αIIbβ3 integrin mediated platelet adhesion to fibrinogen did not significantly affect PKC-δ activity. Tyrosine phosphorylation of PKC-δ was similarly not detected in fibrinogen adherent platelet lysates. Treatment of the platelets with mAb 7E3 prior to the addition of thrombin blocked aggregation having no effect on the thrombin induced PKC-δ activation. We conclude that PKC-δ is activated in platelets by an αIIbβ3 independent pathway

Differential Roles of the PKC Novel Isoforms, PKCδ and PKCε, in Mouse and Human Platelets

Background Increasing evidence suggests that individual isoforms of protein kinase C (PKC) play distinct roles in regulating platelet activation. Methodology/Principal Findings In this study, we focus on the role of two novel PKC isoforms, PKCδ and PKCε, in both mouse and human platelets. PKCδ is robustly expressed in human platelets and undergoes transient tyrosine phosphorylation upon stimulation by thrombin or the collagen receptor, GPVI, which becomes sustained in the presence of the pan-PKC inhibitor, Ro 31-8220. In mouse platelets, however, PKCδ undergoes sustained tyrosine phosphorylation upon activation. In contrast the related isoform, PKCε, is expressed at high levels in mouse but not human platelets. There is a marked inhibition in aggregation and dense granule secretion to low concentrations of GPVI agonists in mouse platelets lacking PKCε in contrast to a minor inhibition in response to G protein-coupled receptor agonists. This reduction is mediated by inhibition of tyrosine phosphorylation of the FcRγ-chain and downstream proteins, an effect also observed in wild-type mouse platelets in the presence of a PKC inhibitor. Conclusions These results demonstrate a reciprocal relationship in levels of the novel PKC isoforms δ and ε in human and mouse platelets and a selective role for PKCε in signalling through GPVI

ICAR: endoscopic skull‐base surgery

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Kontrastmittelinduzierte Nierenfunktionsstörungen gemessen am Serumcystatin C

Kontrastmittel (KM) induzierte Nierenfunktionsstörungen gemessen am Serumcystatin C (CYSC) ein Vergleich zwischen euvolämen (ev) und hypovolämen (hv) Patienten nach Koronarangiographie (HKU)Einleitung: Diese Arbeit untersucht die Auswirkung des Volumenstatus auf CYSC 48 Stunden nach KM Injektion bei HKU. Methode: Es wurden 100 Patienten eingeschlossen, die vor ihrer HKU ein normwertiges Serumkreatinin hatten und sonographisch in ev und hv eingeteilt wurden. Ergebnis: Von 47 ev und 53 hv hatten 8 ev und 21 hv Patienten einen Anstieg des CYSC um >= 10 % der Baseline (CINB) (p = 0,016). Das relative Risiko (RR) von hv Patienten für eine CINB, lag bei RR = 2,327 (p = 0,020). Vorhofflimmern (VHF) RR = 2,384 (p = 0,004), Schleifendiuretika (LD), RR = 1,877 (p = 0,047) und chronische Herzinsuffizienz (CHF) (NYHA >= II) RR = 2,251 p = (0,047) waren Risikofaktoren für die CINB. Diskussion: Hypovolämie, VHF, CHF (NYHA >= II) und die Einnahme von LD erhöhten das Risiko für ein CINB

Enhanced neutrophil p53 activity during killing of Candida yeasts

Neutrophils (PMN) play a pivotal role in host defense against fungal infections. p53 is a phosphoprotein transcriptional factor important to cellular regulation of DNA repair. PMN p53 activity was assessed after 1 h incubation at 37°C of human PMN with viable Candida glabrata (Cg) and Candida albicans (Ca) yeasts. Fungicidal activity was demonstrated without compromise to PMN viability. The DNA binding activity of PMN p53 was enhanced after exposure to viable Candida yeasts. The dimeric conformation of p53 was augmented in nuclear lysates of PMN exposed to Candida yeasts compared with that from unchallenged PMN. Despite greater susceptibility to PMN killing of Cg compared with Ca (79.0% ± 6.9% vs 38.6% ± 15.4%, P\u3c0.05), no differences in p53 activity were detected. The specificity of this PMN p53 activity was confirmed by competitive inhibition with consensus DNA sequences and immunoblotting. Changes in PMN p53 activity and dimeric conformation occur during killing of viable Candida yeasts