Differential Modulation of Keratin Expression by Sulforaphane Occurs via Nrf2-dependent and -independent Pathways in Skin Epithelia

Treatment with the natural chemical sulforaphane (SF) ameliorates skin blistering in keratin 14 (K14)-deficient mice, correlating with the induction of K16 and K17 in the basal layer of epidermis (Kerns et al., PNAS 104:14460, 2007). Here we address the basis for the SF-mediated K16 and K17 induction in mouse epidermis in vivo. As expected, induction of K16 partly depends on the transcription factor Nrf2, which is activated by SF exposure. Strikingly, K17 induction occurs independently of Nrf2 activity and parallels the decrease in glutathione occurring shortly after epidermal exposure to SF. Pharmacological manipulation of glutathione levels in mouse epidermis in vivo alters K17 and K16 expression in the expected manner. We present findings suggesting that select MAP kinases participate in mediating the Nrf2- and glutathione-dependent alterations in K16 and K17 levels in SF-treated epidermis. These findings advance our understanding of the effect of SF on gene expression in epidermis, point to a role for glutathione in mediating some of these effects, and establish that SF induces the expression of two contiguous and highly related genes, K16 and K17, via distinct mechanisms.