The goal of this proposal is to characterize a new mechanism by which the Notch receptor regulates changes in cell adhesion dynamics. Notch signaling is highly conserved across the animal kingdom to regulate cell fates during development, and its dysregulation has been implicated in a variety of vascular inflammatory diseases, developmental abnormalities, and cancers. Binding of ligand to Notch receptor leads to proteolytic cleavages that release the intracellular domain (ICD) as a transcriptional activator, and this mechanism has been the primary focus in describing the role of Notch in development and disease. The investigator has recently found that shear stress caused by blood flow activates Notch, which in turn leads to rapid assembly of endothelial cell-cell junctions and heightened barrier function. In this work, they demonstrated that the transmembrane domain (TMD) left behind after Notch proteolysis initiates the formation of a cortical signaling complex that is responsible for stimulating junction assembly. Here, the investigator will identify the components, underlying mechanisms, and cellular impact of this previously unappreciated non-transcriptional, cortical pathway for Notch and elucidate the biological contexts in which this pathway is engaged. These objectives will be achieved through an interdisciplinary program built around three Aims:
Specific Aim 1 will be to define mechanisms underlying the non-canonical cortical Notch signaling pathway.
Specific Aim 2 will examine crosstalk between adhesion, force, and the cortical Notch signaling pathway.
Specific Aim 3 will be to explore the extent to which the cortical Notch pathway generalizes to broader biological contexts. Together, these studies will offer important insights into this new arm of Notch signaling, and provide a molecular basis for how transcriptional and adhesive programs might be coordinated by a single receptor.
The development and maintenance of tissue structure and function requires coordination between the dynamic physical organization of cells in tissues and the genetic programs controlling cell phenotype. Aberrations in this coordination are the basis for many developmental abnormalities and cancer. This project is designed to uncover basic mechanisms of how a key protein, the Notch receptor, is able to simultaneously orchestrate these physical and genetic processes, and in so doing, reveal novel avenues to treat disease.