Facilitated wound healing by activation of the Transglutaminase 1 gene

Transglutaminase 1 (TGase 1) is a Ca2+-dependent enzyme which catalyzes epsilon-(gamma -glutamyl)lysine cross-linking of substrate proteins such as involucrin and loricrin to generate the cornified envelope at the cell periphery of the stratum corneum. We have shown that disruption of the TGase I gene in mice results in neonatal lethality, absence of the cornified. envelope, and impaired skin barrier function. Based on the importance of TGase I in epidermal morphogenesis, we have now assessed its role in wound healing. In neonatal mouse skin, TGase 1 mRNA as well as keratin 6 alpha was induced in the epidermis at the wound edges as early as 2 hours after injury and that expression continued in the migrating epidermis until completion of re-epithelialization. The TGase 1 enzyme co-localized on the plasma membrane of migrating keratinocytes with involucrin, but not with loricrin, which suggests the premature assembly of the cornified envelope. Similar injuries to TGase 1 knockout mouse skins grafted on athymic nude mice showed substantial delays in wound healing concomitant with sustained K6 alpha mRNA induction. From these results, we suggest that activation of the TGase 1 gene is essential for facilitated repair of skin injury.