Role of Intercellular Junctions in Redistribution of Focal Adhesions and Orientation of Vascular Endothelial Cells Exposed to Cyclic Stretching
The redistribution of focal adhesions (FAs) containing integrin β1 and paxillin plays an important role in the cyclic stretching-induced morphological changes of endothelial cells (ECs). In addition to focal adhesion kinase (FAK), known to be a primary regulator for FA redistribution, intercellular junctions (IJs) have recently been reported to be involved in signaling upstream of FAs. Here, we addressed the role of IJs in the morphological changes and redistribution of FAs in ECs exposed to cyclic stretching. Both confluent and sparse ECs were oriented nearly perpendicularly to the stretch direction after 10 min of exposure. Orientation of sparse ECs, but not confluent ECs, was suppressed by treatment with a phospho-FAK inhibitor. FAK inhibitor blocked integrin β1 redistribution in ECs, which was observed in non-inhibited cells after 10-min stretch exposure. However, paxillin redistribution in confluent ECs was observed regardless of FAK inhibitor treatment after 2-min stretch exposure. When we blocked signals from IJs with an inhibitor of Src homology 2 domain-containing tyrosine phosphatase-2, the percentage of oriented ECs decreased and paxillin redistribution, but not integrin β1, was suppressed. These findings suggest that IJs are involved in the orientation of ECs subjected to cyclic stretching through signaling pathways other than FAK.
KeywordsCyclic stretching Endothelial cells Focal adhesions Intercellular junctions Cell orientation
The authors would like to thank Drs. Ikuo Takahashi and Makoto Takahashi for kindly providing human umbilical cords with the donors’ informed consent. The present study was supported in part by the Tohoku University Global COE Program “Global Nano-Biomedical Engineering Education and Research Network Centre”, and a Grant-in-Aid for Specially Promoted Research (No. 20001007) from Ministry of Education, Culture, Sports, Science and Technology (MEXT).
- 1.Balaban, N. Q., U. S. Schwarz, D. Riveline, P. Goichberg, G. Tzur, I. Sabanay, D. Mahalu, S. Safran, A. Bershadsky, L. Addadi, and B. Geiger. Force and focal adhesion assembly: a close relationship studied using elastic micropatterned substrates. Nat. Cell Biol. 3:466–472, 2001.CrossRefGoogle Scholar
- 3.Bikukov, K. G., J. R. Jacobson, A. A. Flores, S. Q. Ye, A. A. Birukova, A. D. Verin, and J. G. N. Garcia. Magnitude-dependent regulation of pulmonary endothelial cell barrier function by cyclic stretch. Am. J. Physiol. Lung Cell. Mol. Physiol. 285:L785–L797, 2003.Google Scholar
- 8.Dasari, V. R., K. Kaur, K. K. Velpula, D. H. Dinh, A. J. Tsung, S. Mohanam, and J. S. Rao. Downregulation of focal adhesion kinase (FAK) by cord blood stem cells inhibits angiogenesis in glioblastoma. Aging (Albany NY) 2:791–803, 2010.Google Scholar
- 14.Kataoka, N., K. Ujita, K. Kimura, and M. Sato. The morphological responses of cultured bovine aortic endothelial cells to fluid-imposed shear stress under sparse and colony conditions. JSME Int. J. Ser. C 41:76–82, 1998.Google Scholar
- 17.Manes, S., E. Mira, C. Gomez-Mouton, Z. J. Zhao, R. A. Lacalle, and A. C. Martinez. Concerted activity of tyrosine phosphatase SHP-2 and focal adhesion kinase in regulation of cell motility. Mol. Cell. Biol. 19:3125–3135, 1999.Google Scholar
- 20.Möhl, C., N. Kirchgeßner, C. Schäfer, K. Küpper, S. Born, G. Diez, W. H. Goldmann, R. Merkel, and B. Hoffmann. Becoming stable and strong: the interplay between vinculin exchange dynamics and adhesion strength during adhesion site maturation. Cell Motil. Cytoskeleton 66:350–364, 2009.CrossRefGoogle Scholar
- 27.Sakamoto, N., T. Ohashi, and M. Sato. Effect of magnetic field on nitric oxide synthesis of cultured endothelial cells. Int. J. Appl. Electrom. 14:317–322, 2001.Google Scholar
- 28.Shikata, Y., A. Rios, K. Kawkitinarong, N. DePaola, J. G. Garcia, and K. G. Birukov. Differential effects of shear stress and cyclic stretch on focal adhesion remodeling, site-specific FAK phosphorylation, and small GTPases in human lung endothelial cells. Exp. Cell Res. 304:40–49, 2005.CrossRefGoogle Scholar
- 39.Yano, Y., J. Geibel, and B. E. Sumpio. Tyrosine phosphorylation of pp125FAK and paxillin in aortic endothelial cells induced by mechanical strain. Am. J. Physiol. 271:C635–C649, 1996.Google Scholar