Impaired endothelial shear stress induces podosome assembly via VEGF up-regulation.
Podosomes are dynamic cytoskeletal membrane structures with local adhesive and proteolytic activity. They are critically involved in angiogenesis and vascular adaptive growth. Here, we studied in HUVECs and murine small vessels whether shear stress controls podosome assembly and local proteolytic activity. Podosomes were characterized by immunohistochemistry, and their proteolytic activity was assessed as degradation imprints in fluorescent gelatin that was used as growth substrate. Compared with controls (10 dyn/cm(2)), the number of podosomes formed per time was doubled when cells were exposed to low shear stress (0.3 dyn/cm(2)) or even increased 5-fold under static conditions. This was a result of an enhanced expression of VEGF after reduction of shear stress. Consequently, enhanced podosome formation could be prevented by a VEGF receptor antagonist as well by interruption of VEGF signaling via inhibition of PI3K, Src, or p38. Increase of podosome assembly went along with significantly augmented cell motility. In vivo experiments in mouse arteries confirmed increased endothelial podosome numbers when shear stress was abolished by vessel occlusion. We conclude that shear stress, by reducing VEGF release, inhibits podosome assembly. Hence, endothelial cell-mediated matrix proteolysis and migratory activity are inhibited, thereby stabilizing the structure of the vessel wall.-Fey, T., Schubert, K. M., Schneider, H., Fein, E., Kleinert, E., Pohl, U., Dendorfer, A. Impaired endothelial shear stress induces podosome assembly via VEGF up-regulation.
Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany; theres.fey@med.uni-muenchen.de.
Theres
T
Fey
Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany;
Kai Michael
KM
Schubert
Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany;
Holger
H
Schneider
Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany;
Evelyn
E
Fein
Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany;
Eike
E
Kleinert
Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany; German Centre for Cardiovascular Research (DZHK)-Munich Heart Alliance, Munich, Germany; Munich Cluster for Systems Neurology, Munich, Germany.
Ulrich
U
Pohl
Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany; German Centre for Cardiovascular Research (DZHK)-Munich Heart Alliance, Munich, Germany;
Andreas
A
Dendorfer
D000818:Animals; D002465:Cell Movement; D015536:Down-Regulation; D042783:Endothelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D008297:Male; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D000069261:Podosomes / Q000502:physiology*; D013312:Stress, Physiological; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism
D042461:Vascular Endothelial Growth Factor A; C000592875:Kdr protein, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2; D019061:src-Family Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020782:Matrix Metalloproteinases
blood flow; matrix metalloproteinases; proteolysis; vascular remodeling