In order for normal cells to function, they must adhere to their immediate environment, which includes other cells and proteins. In return, cells receive both mechanical and chemical signals from their environment that are important for cellular processes such as migration, proliferation, and gene expression. Defective or improperly regulated adhesion is observed in a wide variety of human diseases, including the major killers cancer and cardiovascular disease.
Research in the Glading lab focuses on unraveling how cell adhesion signaling regulates cellular behavior.
Currently, our work concentrates on how cell-cell adhesion modulates cell growth and differentiation in both the normal and disease state. Our main experimental context is the endothelial cell and the intact blood vessel. Vessel function is reliant on the ability of vessels to maintain an effective barrier between the blood and tissue, which is primarily regulated at the level of the endothelial cell-cell contact (endothelial junctions). Changes in this barrier regulate the normal immune response and contribute to the growth of new vessels (angiogenesis).
Recently, we described KRIT1 as a scaffolding protein that nucleates a signaling complex at sites of endothelial cell-cell contact. In confluent endothelial cells, the KRIT1 complex associates with cell-cell contacts and is required for junctional stability downstream of active Rap1 (Glading et al 2007). KRIT1 also sits at the nexus of multiple signaling pathways, including the canonical beta-catenin pathway (Glading and Ginsberg, 2010), vascular-endothelial growth factor receptor (VEGFR) activation (DiStefano and Glading, in press), RhoA/Rho Kinase activity (Glading et al, 2007), and Notch signaling, which KRIT1 supports or modifies to promote a stable vascular barrier. Our ongoing research aims to understand cell-cell contact impacts global cell signaling by examining how KRIT1 signaling contributes to changes in cellular behavior.
We use KRIT1 deficient endothelial cells (siRNA, CRISPR) and tissues (KRIT1 knockout and KRIT1 endothelial-specific knockout mice) as models to probe the consequence of loss of endothelial cell-cell contact on endothelial behavior and vessel integrity in vitro and in vivo. By using genetic manipulation of KRIT1, we have been able to prove that loss of cell-cell contact stimulates broad changes in gene expression (Glading, 2010), induces vascular permeability in vivo (Corr et al, 2012), and promotes angiogenesis (unpublished data), as just a few examples. By combining molecular and biochemical examination of specific signaling mechanisms with real-time physiology, we are able to establish key signaling events as critical for normal vascular function. In current research, we are using this approach to explore the crosstalk between inflammatory signaling, angiogenesis and cell-cell contact in the relevant physiological contexts of vascular integrity and cancer.