The quest for the function of simple epithelial keratins

Bioessays. 2003 Aug;25(8):748-58. doi: 10.1002/bies.10316.


Simple epithelial keratins K8 and K18 are components of the intracellular cytoskeleton in the cells of the single-layered sheet tissues inside the body. As members of the intermediate filament family of proteins, their function has been a matter for debate since they were first discovered. Whilst there is an indisputable case for a structural cell-reinforcing function for keratins in the mutilayered squamous epithelia of external barrier tissues, some very different stress-protective features now seem to be emerging for the simple epithelial keratins. Even the emerging evidence of pathological mutations in K8/K18 looks very different from mutations in stratified epithelial keratins. K8/K18-like keratins were probably the first to evolve and, whilst stratified epithelial (keratinocyte) keratins have diversified into a large group of keratins highly specialised for providing mechanical stability, the simple epithelial keratins have retained early features that may protect the internal epithelia from a broader range of stresses, including osmotic stress and chemical toxicity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Apoptosis
  • Biological Evolution
  • Epithelium / anatomy & histology
  • Epithelium / physiology
  • Gene Expression
  • Humans
  • Keratins / genetics
  • Keratins / physiology*
  • Mice
  • Models, Biological
  • Mutation
  • Neoplasms / genetics
  • Neoplasms / physiopathology
  • Skin Diseases, Genetic / genetics
  • Skin Diseases, Genetic / physiopathology


  • Keratins