Artikel
Differential Effects of Vasodilatory Prostaglandins on Focal Adhesions, Cytoskeletal Architecture and Migration in Human Smooth Muscle Cells
Differentielle Wirkungen Vasodilatorischer Prostaglandine auf Fokale Adhäsionen, Zytoskelett und Migration
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Veröffentlicht: | 10. August 2005 |
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Gliederung
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Objective: Cyclooxygenases 1 and -2 are expressed in atherosclerotic arteries and local generation of prostacyclin and prostaglandin E2 (PGE2) occurs. However, the role of cyclooxygenases and individual prostaglandins during plaque progression is currently uncertain. The present study characterizes the effect of vasodilatory prostaglandins on morphology, focal adhesion (FA) function and migration in human aortic smooth muscle cells (SMC).
Methods and results: The expression of prostacyclin receptor (IP) and the prostaglandin E (PGE) receptors 1, - 2, - 3 and - 4 (EP1-4) was verified by RT-PCR in SMC. FA and actin cytoskeleton were visualized by paxillin immunostaining and phalloidin staining. The stable prostacyclin analog, iloprost, transiently induced (i) disassembly of FA and stress fibers, (ii) partial retraction and rounding of SMC, (iii) hypophosphorylation of FA-kinase and paxillin as shown by immunoblotting and (iv) inhibition of platelet derived growth factor-BB induced migration in a modified boyden chamber assay. Inhibition of FAK-phosphorylation and morphological changes were mimicked by forskolin and inhibited by H89 and by the protein tyrosine phosphatase inhibitor vanadate. PGE2 was by far less efficient with respect to all parameters investigated. This difference correlated with the respective cAMP-induction in response to iloprost and PGE2.
Conclusion: Inhibition of FAK-phosphorylation and FA-function is a new target of vasodilatory prostaglandins, which might be causally involved in the anti-migratory effects of prostaglandins. The data also suggest that downstream of Gs-coupled prostaglandin receptors and cAMP/PKA the activation of a phosphatase mediates FAK-dephosphorylation. Importantly, prostacyclin analogs and PGE2 differ dramatically with respect to dephosphorylation of FAK and inhibition of migration, which might be of relevance for their respective functions in atherosclerosis.