Epidermolysis bullosa (EB) represents a group of inherited diseases in humans characterized by epidermal fragility and frequently wounded skin following minor trauma. The goal of our research is related to the recent novel finding, made in several laboratories, that certain members of the integrin family of proteins play a dual role for cell-cell and cell-matrix interaction in the epidermis. It is also related to our own discovery of a novel cytoskeletal protein, moesin, that is specifically expressed in extensions of the cell surface in keratinocytes such as filopodia, microvilli or microspikes. Cell surface receptors appear to be concentrated in filopodia and moesin and ezrin, a closely related protein, undergo significant changes in distribution during normal fetal development of the epidermis and during wound healing. Filopodial activity is part of normal cell behavior in vitro and in vivo, but activated cells show heightened activity. Because of the relationship of this normal cellular activity with cell-cell, cell-matrix interaction, spreading, growth, motility, chemotaxis and tumor cell invasion, we would like to exploit this phenomenon to determine whether it is linked to specific disease states in addition to the physiologic healing response. We propose to investigate these proteins in skin samples from normal and EB patients, in healing wounds, in normal and EB-derived keratinocytes, during their differentiation in culture, during migration (with D. Woodley, Project II), in reconstituted skin and transplants in immunocompromised mice (with J. McGuire and Y. Kim, Project IV), and to study their phosphorylation in addition in A431 cells. We will also use adhesion of keratinocytes to different substrates as an assay to attempt to discriminate between normal and EB-derived cells. We believe that we will not only learn a great deal about the biology of normally differentiating keratinocytes, but also that these molecular systems provide sensitive indicators to discover cellular alterations important in the pathogenesis of EB.