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sPLA(2) cooperates with cPLA(2)alpha to regulate prostacyclin synthesis in human endothelial cells
R A Houliston1, C P Wheeler-Jones
1Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, United Kingdom. rhoulist@rvc.ac.uk
Biochemical and Biophysical Research Communications
|September 28, 2001
Summary
Secretory phospholipase A2 (sPLA2) enhances prostacyclin (PGI2) production in endothelial cells by activating cytosolic phospholipase A2 (cPLA2)alpha. This cross-talk mechanism involves MAPK signaling pathways, increasing arachidonic acid release.
Area of Science:
- Biochemistry
- Cell Biology
- Endothelial Cell Function
Background:
- Prostacyclin (PGI2) synthesis is crucial for vascular homeostasis.
- The initial step involves arachidonic acid (AA) release mediated by cytosolic phospholipase A2 alpha (cPLA2alpha).
- The role of secretory phospholipase A2s (sPLA2s) in this process is not fully understood.
Purpose of the Study:
- To investigate the effect of sPLA2s on PGI2 production in human umbilical vein endothelial cells (HUVEC).
- To elucidate the signaling pathways involved in sPLA2-mediated PGI2 generation.
Main Methods:
- Exposure of HUVEC to varying concentrations and durations of sPLA2.
- Measurement of AA release and PGI2 production.
- Inhibition studies using AACOCF3 (cPLA2alpha inhibitor) and PD98059 (MEK inhibitor).
- Analysis of cPLA2alpha and MAPK phosphorylation states.
Main Results:
- sPLA2 exposure dose- and time-dependently increased AA release and PGI2 generation in HUVEC.
- sPLA2-stimulated AA mobilization was inhibited by AACOCF3, indicating cross-talk with cPLA2alpha.
- sPLA2 induced cPLA2alpha phosphorylation and activation of MAPK pathways (p42/44 MAPK, p38 MAPK, JNK).
- PD98059 attenuated sPLA2-induced cPLA2alpha phosphorylation and PGI2 release.
Conclusions:
- sPLA2 cooperates with cPLA2alpha in a MAPK-dependent manner to regulate PGI2 generation.
- Cross-talk between sPLA2 and cPLA2alpha is a significant mechanism for enhancing prostanoid production in endothelial cells.