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Platelet activating factor modulates signal transduction in Dictyostelium
C Sordano1, E Cristino, F Bussolino
1Department of Clinical and Biological Sciences, University of Turin, Ospedale S. Luigi, Orbassano-Torino, Italy.
Journal of Cell Science
|January 1, 1993
Summary
Platelet-activating factor (PAF) modulates cellular signaling in Dictyostelium discoideum. PAF specifically enhances responses to cyclic adenosine monophosphate (cAMP) and stimulates calcium uptake, suggesting a role in signal transduction pathways.
Area of Science:
- Cellular and Molecular Biology
- Biochemistry
- Developmental Biology
Background:
- Dictyostelium discoideum cells synthesize platelet-activating factor (PAF) during development.
- PAF synthesis is transiently induced by external cyclic adenosine monophosphate (cAMP) pulses.
Purpose of the Study:
- To investigate the role of PAF in signal transduction pathways in Dictyostelium discoideum.
- To determine the effects of PAF on cAMP-regulated cellular responses.
Main Methods:
- Testing the effects of PAF on light-scattering oscillations, cAMP relay, cGMP levels, and extracellular calcium uptake.
- Utilizing specific PAF enantiomers (R-PAF, S-PAF) and lyso-PAF to assess specificity.
- Measuring cellular cAMP and cGMP concentrations and extracellular Ca2+ uptake.
Main Results:
- PAF specifically interferes with spike-shaped light-scattering oscillations, increasing amplitude but not phase or frequency.
- PAF amplifies the light-scattering response to cAMP when cells fail to oscillate spontaneously.
- PAF stimulates extracellular Ca2+ uptake independently of cAMP and shows stereospecificity for the R-enantiomer.
Conclusions:
- PAF acts as a modulator of signal transduction in Dictyostelium discoideum.
- PAF likely interacts with an intracellular acceptor involved in regulating membrane Ca2+ channels and cyclase activity.
- The R-enantiomer of PAF is responsible for the observed biological effects.