Molecular cloning and characterization of AP-2 epsilon, a fifth member of the AP-2 family.

The mammalian AP-2 family of transcription factors consists of four members, AP-2 alpha, AP-2 beta, AP-2 gamma and AP-2 delta, which play an important role in regulating gene expression during development and differentiation of multiple organs and tissues. The defining feature of the AP-2 family is a highly conserved carboxy-terminal basic helix-turn-helix domain that is involved in dimerization and sequence-specific DNA-binding. In this report, we use bioinformatics to identify both the mouse and human AP-2 epsilon, a fifth member of the AP-2 family. The predicted mouse and human AP-2 epsilon proteins consist of 442 amino acids and show a high level of sequence similarity with other AP-2 proteins in the DNA-binding and dimerization domain and weak similarity in the N-terminal activation domain. Northern blot analysis reveals that among the adult mouse tissues examined, AP-2 epsilon is highly expressed in skin tissue. The human AP-2 epsilon gene maps to chromosome 1p42, consists of seven exons spanning 23 kb and exhibits a genomic structure similar to other AP-2 family members. Human AP-2 epsilon mRNA is expressed in human skin and keratinocytes grown in culture. Finally, we show that recombinant AP-2 epsilon can bind to AP-2 binding sequences from keratin promoters in electrophoretic mobility shift assays. Our study establishes AP-2 epsilon as a novel member of the AP-2 family, and suggests that it may play an important role in skin biology.