There is increasing evidence that the attachment of the endothelium to its underlying basement membrane (BM) and the continuity between the endothelium and smooth muscle layer are crucial for force detection within the vessel wall and mechanotransduction. Laminin α5 is a critical component of endothelial BMs. Ex vivo experiments performed in the first SmArt funding period using excised mesenteric arteries from mice lacking laminin α5 in the endothelial BM revealed an almost complete absence of vessel dilation in response to increased shear flow1. Atomic force experiments performed with isolated cells and excised vessels implicate laminin α5 in cortical actin stiffness.
Hypothesis: Receptor mediated adhesion of endothelial cells to laminin α5 in the endothelial cell BM impacts on actin organization and dynamics and hence vessel physiology.
Objectives: 1: To define the receptors on the endothelial cells that recognize laminin α5, the signalling pathways induced, and how this impacts on actin cytoskeleton dynamics. 2: To investigate the impact of laminin α5 on the expression and function of endothelial cell junctional molecules (eg VE-cadherin, PECAM-1)2.
Training: The ESR will be trained in biochemical techniques to study endothelial cell binding to laminin α5 contain α1 and α3 integrins, as well as their impact actin dynamics and the expression of mechanosensitive genes, including genes coding for junctional proteins. Primary endothelial cells will be employed in adhesion assays to define the precise receptors complexes mediating adhesion to laminin α5 containing isoforms. Together with LMU and UKH, the dynamic imaging of actin will be studied in endothelial cells isolated from mice carrying GFP-tagged actin3 and plated on laminin 511 versus other laminin isoforms or other ECM molecules. Whole animal imaging of vascular remodelling will be investigated using the thoracic aortic constriction models in the endothelial specific laminin α5 KO mice using molecular SPECT and PET imaging technologies4, providing the basis of establishing imaging strategies for cardiovascular remodelling in patients.
1Yousif, L.(2012) Cell Adhes Migrat (in press); 2Tzima (2005) Nature 426-31; 3Riedl. 2010. Nat Methods 7, 168-9; 4Schäfers , (2010) J Nucl Med 51:663-6.
Di Russo, J., Hannocks, M.J., Luik, A.L., Song, J., Zhang, X., Yousif, L., Aspite, G., Hallmann, R., and Sorokin, L. (2016). Vascular laminins in physiology and pathology. Matrix Biol., doi: 10.1016/j.matbio.2016.06.008.
Di Russo, J., Luik, A.L., Yousif, L., Budny, S., Oberleithner, H., Hofschröer, V., Klingauf, J., vanBavel, E., Bakker, E.N., Hellstrand, P., Bhattachariya, A., Albinsson, S., Pincet, F., Hallmann, R., Sorokin, L.M. (2017). Endothelial basement membrane laminin 511 is essential for shear stress response. EMBO J., 36, 183-201.
Ph.D student / post-doc
Prof. Lydia Sorokin