Transglutaminases (TGs) are structurally and functionally related
enzymes that modify the post-translational structure and activity of
proteins or
peptides, and thus are able to turn on or switch off their function. Depending on location and activities, TGs are able to modify the signalling, the function and the fate of cells and extracellular connective tissues. Besides mouse models, human diseases enable us to appreciate the function of various TGs. In this study,
skin diseases induced by genetic damages or autoimmune targeting of these
enzymes will be discussed. TG1, TG3 and TG5 contribute to the cutaneous barrier and thus to the integrity and function of epidermis. TGM1 mutations related to autosomal recessive
ichthyosis subtypes, TGM5 mutations to a mild
epidermolysis bullosa phenotype and as novelty TGM3 mutation to
uncombable hair syndrome will be discussed. Autoimmunity to TG2, TG3 and TG6 may develop in a few of those genetically determined individuals who lost tolerance to
gluten, and manifest as coeliac disease,
dermatitis herpetiformis or
gluten-dependent neurological symptoms, respectively. These
gluten responder diseases commonly occur in combination. In
autoimmune diseases, the
epitope spreading is remarkable, while in some inherited pathologies, a unique compensation of the lost
enzyme function is noted.