Cytokeratin 4: Proteins and Enzymes

Keratins are a family of structurally related proteins that form the intermediate filament cytoskeleton in epithelial cells. White sponge nevus (WSN) is a benign autosomal dominant disorder which affects non-cornifying stratified squamous epithelial. Keratins are expressed in pairs by epithelial cells in a tissue and cell specific manner. The major differentiation specific keratins of the buccal mucosa, nasal, esophageal and anogenital epithelia are CK-4 and CK-13. The tissue distribution and nature of the lesions in patients affected by WSN suggested that mutations in CK-4 and/or CK-13 might be responsible for this disorder (1). K4 and K13 form heterodimers in normal epithelial cells. In humans, K4 is present in all layers of the epidermis at 10 weeks and gradually disappears, starting from the basal layers at 15 weeks and becoming totally absent at around 20 weeks. This period corresponds to the early fetal period when melanoblasts derived from the neural crest migrate through the dermis into the basal layer of the epidermis (2)