Desmosomes are special adhesion structures connecting epithelial cells. The formation of desmosome plaques requires the participation of multiple molecules including desmoplakin (DP), plakoglobin (PG), desmocollins (DSC), and desmogleins (Dsg). It is known that Dsg has functional domains involved in cell-cell adhesions and plaque-cytoskeleton interactions. Functional modulation of Dsg is known to be related to some skin disorders exhibiting desmosome abnormalities. To better understand the role of Dsg 3 in the assembly of epidermal desmosomes and its possible relation to cutaneous disorders, we generated a transgenic mouse model which, driven by a keratin 14 promoter, expressed high levels of a truncated Dsg 3, Dsg3ΔN, in the lower epidermal keratinocytes.
Skin samples of different body sites were collected, at different ages, from both control mouse and mutant animals exhibiting phenotypic skin changes for histology, immunohistochemistry, and ultrastrucutral studies. Specimens for conventional TEM studies were fixed in 4% paraformaldehyde and 2.5% glutaraldehyde, post-fixed in 1% OsO4, and embedded in LX-112. For immunoelectron microscopy, samples were fixed in 2% paraformaldehyde and 0.05% glutaraldehyde, dehydrated in ethanol at -25°C, embedded in Lowicryl K4M medium, and polymerized at -25°C with UV light. Ultrathin sections were labeled with several antibodies against DP, PG, DSC, and E-cadherin. All sections were stained with uranyl acetate and lead citrate before examining with a JEOL-CX microscopy operated at 60 kv.