Expression of Laminin γ2 Proteolytic Fragments in Murine Skin Following Exposure to Sulfur Mustard.

Laminin-332 is a basement membrane protein composed of three genetically distinct polypeptide chains that actively promote both skin epidermal cell adhesion and migration. Proteolytic fragments of the laminin gamma 2 chain stimulate migration and scattering of keratinocytes and cancer cells. Sulfur mustard (SM) is a bifunctional alkylating agent that induces separation of basal keratinocytes from the dermal-epidermal junction and invokes a strong inflammatory response leading to delayed wound repair. In the present studies, the role of laminin gamma 2 in SM-induced skin injury and wound repair was investigated using the mouse ear vesicant model. We found that laminin gamma 2 chain mRNA was preferentially upregulated in mouse ear skin exposed to SM. In situ hybridization confirmed overexpression of laminin gamma 2 transcript. Western blot analysis showed increased protein expression of the full-length proform of laminin gamma 2 and smaller processed fragments of laminin gamma 2 in skin exposed to SM. Dual immunofluorescence labeling indicated that laminin gamma 2 fragments are prevalent in suprabasal keratinocytes behind the leading edge in areas of hyperplasia in injured skin. In addition, co-expression of laminin gamma 2 and the senescent marker, p16(-INK4a) was found to overlap with the hyperplastic migratory epithelial sheet. This observation is similar to hypermotile keratinocytes reported in invasive carcinoma cells. Overall, our studies indicate that laminin gamma 2 is preferentially expressed in skin post SM exposure and that protein expression appears to become progressively more fragmented. The laminin gamma 2 fragments may play a role in regulating SM-induced skin wound repair. Anat Rec, 2020. (c) 2020 American Association for Anatomy