THE EPIDERMAL KERATINOCYTE AS A MODEL FOR THE STUDY OF GENE-REGULATION AND CELL-DIFFERENTIATION

The epidermis is a dynamic, continually renewing structure that provid es the organism with a life-sustaining interface with the environment. The major cell type of the epidermis, the epidermal keratinocyte, und ergoes a complex and carefully choreographed program of differentiatio n. Aberrations in this process result in the genesis of a variety of d ebilitating and life-threatening diseases. In the present paper, we di scuss the keratinocyte differentiation program and the exogenous agent s that regulate differentiation. We describe the marker genes that hav e been utilized to study the process of gene regulation in epidermis. We describe the keratin proteins and studies that have identified kera tin mutations that cause epidermal disease. We present recent informat ion on regulation of keratinocyte gene expression and attempt to summa rize current knowledge on the role of transcription factors in this pr ocess. We also discuss the process of cornified envelope assembly and the structure and function of the proteins that are thought to be prec ursors of this structure.