Keratinocytes

Epidermal keratinocytes (skin cells) are highly specialized epithelial cells designed to perform a very specific function, separation of the organism from its environment. To accomplish this, the cells synthesize precursors and assemble them into two distinct structures, the cornified envelope and keratin intermediate filaments. The intermediate filaments are assembled from keratin monomers and the cornified envelope is assembled from a protein called involucrin and several other proteins. Expression of involucrin and the keratins genes are regulated as a function of the stage of keratinocyte differentiation and by various external agents such as calcium and vitamin A.