- The hypothesis of this revised application is that epithelial cell motility is suppressed by signals generated as a result of E-cadherin mediated cell-cell contact. Published findings from the principal investigator's lab have shown that the catenin binding domain of E-cadherin is required for adhesion, but not for suppression of motility, whereas the JM domain (comprising 30-50 amino acids just next the to plasma membrane) suppresses motility but does not support adhesion in many cell types. Data from a new collaborator, Michael Kinch, indicate that engagement of E-cadherin stimulates the tyrosine phosphorylation of several proteins in breast epithelial cells and MDCK cells. A new specific aim (Aim 1) based on these data is to determine whether this is the case for keratinocytes as well and then determine which parts of the E-cad tail are required to generate this tyrosine phosphorylation response and identify tyrosine-phosphorylated proteins.
Aim 2 proposes to identify components that interact with the JM domain of E-cadherin and test their role in suppression of motility.
The final aim i s to determine the role of the JM domain in regulating the motility of keratinocytes in vitro and in vivo. This will be accomplished first by expressing dominant-negative forms of E-cadherin and N-cadherin in cultured cells, and then using the K14 promoter to target selected dominant-negative constructs to the epidermis of transgenic mice.
