Abstract 723: Vimentin Provides The Essential Scaffold For Pkg Mediated Vasp Phosphorylation Necessary For Endothelial Migration And Proliferation
Endothelial cell migration plays an important role in many physiological and pathological conditions. We recently showed that the intermediate filament vimentin is upregulated in endothelial cells with high migratory capacity. Here, we demonstrate that vimentin expression is also upregulated in collateral arteries where high shear forces lead to vascular remodeling. Furthermore, we present a functional impact of vimentin on cell migration and the identification of the underlying signal transduction pathway. Vimentin suppression using siRNA technique significantly decreased migration velocity by 50% in videomicroscopic analyses, diminished transmigration activity by 42.5% in a Boyden chamber assay and reduced proliferation by 43% in a BrdU-incorporation assay. Vimentin colocalized with VASP and PKG in endothelial cells as demonstrated via confocal microscopy (VASP-VImentin: Fig. a-b⇓). Vimentin suppression was accompanied with a translocation of VASP from focal contacts to the perinuclear region and the nucleus. These findings appeared to be essential for proper PKG mediated VASP phophorylation because we detected a diminished expression of PKG and pSer239 VASP in vimentin suppressed cells. Our results suggest, that the scaffold provided by vimentin is essential for VASP localization and PKG mediated VASP phosphorylation and thus controls endothelial cell migration and proliferation. The dependency of VASP phosphorylation on vimentin represents an example of how changes in the cytoskeletal composition affect important biochemical signaling pathways.