phaidra.vetmeduni.ac.at o:1421 DOI 10.3390/ijms24032193 Transglutaminase Activity is conserved in Stratified Epithelia and Skin Appendages of Mammals and Birds The cross-linking of structural proteins is critical for establishing the mechanical stability of the epithelial compartments of the skin and skin appendages. The introduction of isopeptide bonds between glutamine and lysine residues depends on catalysis by transglutaminases and represents the main protein cross-linking mechanism besides the formation of disulfide bonds. Here, we used a fluorescent labeling protocol to localize the activity of transglutaminases on thin sections of the integument and its appendages in mammals and birds. In human tissues, transglutaminase activity was detected in the granular layer of the epidermis, suprabasal layers of the gingival epithelium, the duct of sweat glands, hair follicles and the nail matrix. In the skin appendages of chickens, transglutaminase activity was present in the claw matrix, the feather follicle sheath, the feather sheath and in differentiating keratinocytes of feather barb ridges. During chicken embryogenesis, active transglutaminase was found in the cornifying epidermis, the periderm and the subperiderm. Transglutaminase activity was also detected in the filiform papillae on the tongue of mice and in conical papillae on the tongue of chickens. In summary, our study reveals that transglutaminase activities are widely distributed in integumentary structures and suggests that transglutamination contributes to the cornification of hard skin appendages such as nails and feathers. eng Transglutaminase Cornification Keratinocytes Epidermis Filiform Pappilae Nail Feather Sweat Gland Eccrine Gland Gingiva Chicken Evolution Enzyme Activity Labeling 2023-03-14T13:45:54.128Z LOMv1.0 Author BEGIN:VCARD VERSION:3.0 N:Sachslehner;Attila Placido; FN:Attila Placido Sachslehner X-ORCID:https://orcid.org/0000-0003-1447-9254 END:VCARD BEGIN:VCARD VERSION:3.0 N:Eckhart;Leopold; FN:Leopold Eckhart X-ORCID:https://orcid.org/0000-0002-5645-2036 END:VCARD BEGIN:VCARD VERSION:3.0 N:Gruber;Reinhard; FN:Reinhard Gruber END:VCARD BEGIN:VCARD VERSION:3.0 N:Kuchler;Ulrike; FN:Ulrike Kuchler END:VCARD BEGIN:VCARD VERSION:3.0 N:Hess;Claudia; FN:Claudia Hess X-ORCID:https://orcid.org/0000-0002-3535-5157 END:VCARD BEGIN:VCARD VERSION:3.0 N:Jäger;Karin; FN:Karin Jäger END:VCARD BEGIN:VCARD VERSION:3.0 N:Geiselhofer;Miriam; FN:Miriam Geiselhofer END:VCARD BEGIN:VCARD VERSION:3.0 N:Golabi;Bahar; FN:Bahar Golabi END:VCARD BEGIN:VCARD VERSION:3.0 N:Surbek;Marta; FN:Marta Surbek END:VCARD https://w3id.org/kim/hcrt/scheme https://w3id.org/kim/hcrt/text Textdokument Text LOMv1.0 yes https://creativecommons.org/licenses/by/4.0 application/pdf 7012180 https://phaidra.vetmeduni.ac.at/o:1421 https://phaidra.vetmeduni.ac.at/api/object/o:1421/thumbnail LOMv1.0 discipline