title: Deletion of integrin linked kinase in endothelial cells results in defective RTK signaling caused by caveolin 1 mislocalization.
abstract: Integrin linked kinase (ILK) connects the ILK-Pinch-Parvin complex with integrin adhesion sites. Because of the functional relevance of integrin-linked signaling for endothelial cell (EC) biology, we have explored this pathway in Ilk(-/-) embryonic stem (ES) cells differentiated into ECs and vessel-like structures. We have focused in particular on the mechanistic relevance of ILK-Pinch-Parvin complex-related signaling for EC development and tube formation. Our analysis revealed that the formation of vessel-like structures was strongly reduced in Ilk(-/-) ES cells and that this phenotype could be rescued by re-expression of ILK in ES cells. ECs were MACS sorted from wild-type (WT) and Ilk(-/-) ES cells and functional analysis using intracellular calcium imaging as the read-out yielded a complete lack of vascular endothelial growth factor- and epidermal growth factor-dependent responses. The possibility of a caveolin 1-related defect was investigated by transfecting WT and Ilk(-/-) ECs with a caveolin 1-EGFP fusion protein. Time-lapse microscopy showed that the prominent phenotype is due to altered dynamics of caveolin 1 and to a lack of positioning of caveolin 1 in the vicinity of the plasma membrane and that it is rescued by re-expressing ILK in the Ilk(-/-) ES cells. We also found that the defect is caused by the perturbed organization of microtubules and cortical actin filaments. Thus, ILK is required as a scaffold to allow actin-microtubule interactions and correct positioning of caveolin 1 close to the plasma membrane. This is crucial for signaling compartmentalization in ECs and explains the key role of ILK for EC development and function.
authors: Institute of Physiology I, Life and Brain Center, University of Bonn, Bonn, NRW, 53105, Germany.
authors: Daniela
authors: D
authors: Malan
authors: Andrea
authors: A
authors: Elischer
authors: Michael
authors: M
authors: Hesse
authors: Sara A
authors: SA
authors: Wickström
authors: Bernd K
authors: BK
authors: Fleischmann
authors: Wilhelm
authors: W
authors: Bloch
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism; D000818:Animals; D051242:Caveolin 1 / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism* / Q000502:physiology; D017353:Gene Deletion; D051379:Mice; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D021381:Protein Transport / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014018:Tissue Distribution / Q000235:genetics; D000099200:Scaffold Protein ILK
chemical_list: D051242:Caveolin 1; D017346:Protein Serine-Threonine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D000099200:Scaffold Protein ILK