James A. Marrs, PhD

My research addresses the role of cadherin-mediated cell-cell adhesion in theestablishment and maintenance of epithelial cell polarity and the role of cadherins incellular differentiation. Cadherins are a large superfamily of molecules which mediatecalcium dependent cell-to-cell adhesion, and these molecules are involved in severalcellular, developmental and disease processes. Our data demonstrates that cadherinfamily members differ in their abilities to induce specialized epithelial cell phenotypesincluding Na+, K+-ATPase cell surface polarity and membrane-cytoskeleton proteinexpression. We are investigating the mechanism used by cadherins to alter epithelialcell polarity. Two polarized simple epithelia, the choroid plexus and retinal pigmentepithelia are being used to study how an apical Na+, K+-ATPase cell surfacedistribution is established and maintained. These epithelia provide excellent modelsystems to compare with the renal epithelium which has a basal-lateral Na+, K+-ATPasedistribution. For these studies we employ a combination of cell biological and molecularbiological techniques, including laser scanning confocal microscopy, analysis ofsynthesis and catabolism of proteins, transfection and expression of proteins in tissueculture cells, and the yeast two hybrid system for studying protein-protein interactions.We are also using cDNA cloning techniques to identify new cadherin gene superfamilymembers that may influence differentiation in other cell types.