Modulation of Endothelial Tight Junctions by Thrombospondin-1

• Applicant: Dr. Torsten Kirsch
• Subject Area: Nephrology
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 167884624

Autoimmune vasculitides are characterized by microinflammation with endothelial activation, increased permeability and leukocyte infiltration. We recently described a novel mechanism in which apoptotic cells induce endothelial activation and enhanced release of the extracellular glycoprotein thrombospondin-1 (TSP-1). We now want to test the hypothesis that TSP-1 modulates tight junction architecture in endothelial cells and thus alters barrier functions. In this proposal we will analyze the impact of TSP-1 on phosphorylation, internalization and (re-) distribution of the transmembrane tight junction proteins occludin, claudin-5 and tricellulin and assess alterations in paracellular permeability, transelectrical resistance, leukocyte infiltration and migration. We will use fusion-constructs of these proteins and life-cell imaging to determine the temporal pattern of TSP-1-induced opening of endothelial tight junctions. Moreover, we will analyze the intracellular pathways induced by TSP-1 with a special emphasis on the phosphatidylinositol-3 kinase/protein kinase B (PI3K/AKT) and rhoA/rho kinase (ROCK) pathways as well as involvement of the β-catenin/ forkhead box factor 01 (FoxO1) transcription factor complexes. These studies will help to gain deeper insight into the complex interactions taking place at the endothelial border in vascular inflammatory diseases.

• DFG Programme: Research Grants