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Keratins are the epithelial-specific members of the superfamily of intermediate filament (IF) genes and proteins. The 28 type I and 26 type II keratin genes are regulated in a pairwise fashion, reflecting the heteromeric nature of the 10 nm filaments they form, as well as in a tissue-specific and differentiation-dependent fashion in the body, giving rise to expression patterns that are very useful to define the status of epithelia in health and disease. Keratin IFs fulfill two major functions: structural support, without which incident physical trauma exposes an inherent fragility and leads to loss of cell integrity, and regulation of several basic cellular processes such as growth, proliferation, apoptosis, made possible by interactions with various cellular proteins.

Publisher Summary Skin, by virtue of its location at the interface with the outside world, is one of the largest organs in the body that fulfills a number of important functions, undergoes constant renewal, and enjoys significant clinical relevance, as well as social importance. This chapter contains methods that are particularly useful for the basic characterization of transgenic mouse models in which the expression of keratin genes has been manipulated. Mouse skin presents several advantages for the study of the mechanisms regulating the expression of keratin genes and the properties, regulation, and function of their protein products, for example, a very large fraction of the known keratin genes are differentially expressed in skin epithelia and other IF genes are expressed in nonepithelial compartments of the skin. The compact nature of mouse keratin genes makes their manipulation through genetic engineering in relatively straightforward manner. The methods and assays outlined in the chapter are typically needed during the initial analysis of mice in which the expression of a gene, keratin, or other is manipulated in skin tissue. These methods, thus, have and will continue to be a mainstay in the characterization of the regulation and function of keratin genes in epithelial tissues.