Drebrin as a regulator of endothelial cell-cell and cell-matrix contact

• Applicant: Professor Dr. Stefan Linder
• Subject Area: Cell Biology
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 252069543

This project investigates the role of the f-actin binding protein drebrin and its interaction partners in the regulation of endothelial integrity. The formation of blood vessels and the maintenance of endothelial integrity depends on the fine-tuned regulation of both cell-matrix and cell-cell contacts. In both cases, cytoskeleton-dependent processes, and especially f-actin dynamics, play an important role. It is an intriguing thought that cytoskeletal proteins which are present at both locations would be ideally placed for the coordinated regulation of both cell-matrix and cell-cell adhesion. One such candidate protein is drebrin (developmentally regulated brain protein). Drebrin localizes to adherens junctions in human endothelial cells, and we could recently show that drebrin preserves cell-cell contact integrity in human umbilical endothelial cells (HUVEC) by stabilizing the nectin-afadin system at adherens junctions. Moreover, we could show that drebrin and afadin are also components and critical regulators of travelling actin waves, which are dynamic cell-matrix contacts in endothelial cells and a variety of other cell types. Fusion of actin waves with the cell periphery results in the generation of local protrusions, and contact of these protrusions with neighbouring cells leads to enrichment of actin wave components at the cell-cell interface. Wave-deposited junctional proteins are thus in an ideal position to establish new cell-cell contacts.The proposed project is focused on the roles of drebrin in endothelial cell-cell contact and cell-matrix/actin wave regulation, but also on the likely connections between both processes. Moreover, we will elucidate the roles of novel drebrin interacting proteins in cell-cell and cell-matrix adhesion. For this, we will follow up several lines of evidence: First, we will investigate drebrin´s molecular mode of action in regulating the interaction between afadin and nectin, which involves a likely conformational change in the afadin molecule induced or stabilized by binding of drebrin. Second, we will focus on the role of drebrin and other cell-cell junctions molecules, especially afadin, in the regulation of travelling actin waves in subconfluent cells. The third major point will be the analysis of the novel drebrin binding partners alpha II spectrin, Crk and the Treacher Collins Syndrome-associated protein TCOF1/treacle, their respective interactions with drebrin, as well as their role in drebrin-regulated cell-matrix and cell-cell adhesion in the endothelium. Each of these approaches will by itself reveal new and important information about the role of drebrin and its interactors in the dynamic regulation of the endothelial cytoskeleton. Combined, they could reveal novel connections between endothelial cell-matrix and cell-cell adhesion. This potential connection will form the forth focus of the work plan.

• DFG Programme: Research Grants