Regulatory role of protein tyrosine phosphorylation in platelet activating factor-induced signal transduction in platelets

Zhongguo Yao Li Xue Bao. 1999 Feb;20(2):157-61.

Abstract

Aim: To study the role of protein tyrosine phosphorylation (PTP) in platelet activating factor (PAF)-induced platelet signal transduction cascade.

Methods: Washed rabbit platelets were used to test the inhibitory effect of genistein (Gen) on platelet aggregation and serotonin secretion. Intracellular Ca2+ ([Ca2+]i) and pH (pHi) were measured by a dual wavelength fluorophotometer with Fura 2-AM and BCECF-AM. PTP was determined with a specific anti-phosphotyrosine monoclonal antibody by Western blotting.

Results: Pretreatment with Gen (100 and 200 mumol.L-1) inhibited PAF (20 nmol.L-1)-stimulated platelet serotonin release by 23.7% +/- 2.0% and 41% +/- 8%, respectively. Similar inhibitory effects of Gen were observed on PAF-evoked increase of [Ca2+]i and intracellular alkalization. PAF also elicited a pronounced increase in PTP of several bands with M(r) 70,000, 60,000, 50,000, 42,000/40,000, and 34,000, which were suppressed markedly by Gen 200 and 400 mumol.L-1. Pretreatment with staurosporine (Sta) 20 nmol.L-1, BAPTA 200 mumol.L-1, and egtazic acid 2 mmol.L-1 to inhibit PKC activation, [Ca2+]i elevation, and Ca2+ influx respectively, also showed an inhibitory effects on the formation of PTP.

Conclusion: PTP is involved in multiple signal transduction pathways induced by PAF, on which PKC activation and calcium mobilization play a regulatory role.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Platelets / metabolism
  • Calcium / blood
  • Genistein / pharmacology*
  • Phosphorylation / drug effects
  • Platelet Activating Factor / pharmacology*
  • Platelet Aggregation / drug effects
  • Protein-Tyrosine Kinases / metabolism
  • Protein-Tyrosine Kinases / physiology*
  • Rabbits
  • Serotonin / blood
  • Signal Transduction*

Substances

  • Platelet Activating Factor
  • Serotonin
  • Genistein
  • Protein-Tyrosine Kinases
  • Calcium