Investigation of mouse amniotic fluid for stimulating ability of keratinocyte differentiation depending on the fetal stage.

During fetal development, the barrier function of the fetal skin is developed under specific conditions for epidermis formation. In keratinocyte differentiation, the well-orchestrated production and modification of various structural proteins are induced. We assessed the epidermal barrier function in different fetal stages by evaluating the enzymatic activity of cross-linking proteins, transglutaminases, and the permeation of fluorescence dye in the stained epidermal sections.

Studies on differentiation-dependent expression and activity of distinct transglutaminases by specific substrate peptides using three-dimensional reconstituted epidermis.

During skin formation, particularly during differentiation of keratinocytes, unique post-translational modifications play a role in forming a proteinaceous supermolecule called the cornified envelope (CE), which is necessary for barrier function. Transglutaminases (TGs) are essential enzymes involved in the cross-linking of various keratinocyte structural proteins to complete CE formation. The TG family consists of eight isozymes, with two members, TG1 and TG3, located mainly in the epidermis.