p63 directly induces expression of Alox12, a regulator of epidermal barrier formation.

Epidermal development and differentiation are tightly controlled processes that culminate in the formation of the epidermal barrier. A critical regulator of different stages of epidermal development and differentiation is the transcription factor p63. More specifically, we previously demonstrated elsewhere that p63 is required for both the commitment to stratification and the commitment to terminal differentiation. We now demonstrate that DeltaNp63alpha, the predominantly expressed p63 isoform in postnatal epidermis, also plays a role in the final stages of epidermal differentiation, namely the formation of the epidermal barrier. We found that DeltaNp63alpha contributes to epidermal barrier formation by directly inducing expression of ALOX12, a lipoxygenase which contributes to epidermal barrier function. Our data demonstrate that DeltaNp63alpha directly interacts with the promoter of Alox12 in the developing epidermis. Furthermore, we found that the induction of Alox12 expression by DeltaNp63alpha depends on intact p63 binding sites in the Alox12 promoter. Finally, we found that DeltaNp63alpha can induce Alox12 expression only in differentiating keratinocytes, consistent with the role of ALOX12 in epidermal barrier formation.