Transcription factor AP-2 is tissue-specific in Xenopus and is closely related or identical to keratin transcription factor 1 (KTF-1).

This paper identifies a new, developmental role for transcription factor AP-2 in the activation of amphibian embryonic epidermal keratin gene expression. Keratin transcription factor KTF-1 is shown by several criteria to be identical or closely related to AP-2. KTF-1/AP-2 is shown to be tissue-specific from its first transcription in Xenopus embryos, and restricted to a small number of adult tissues, including skin. Epidermis-specific keratin transcription closely follows specification of the embryonic ectoderm in Xenopus, and is subject to regulation by growth factors and embryonic induction. We further show that in mouse basal keratinocytes, a KTF-1/AP-2-like factor is present and binds to a DNA sequence previously shown to be important in the regulation of the keratin K14 gene, which is actively expressed in these cells. Thus, the study of AP-2 and its role in the regulation of keratin gene transcription should enhance our understanding of both amphibian embryonic development and mammalian skin differentiation.