Molecular cloning and characterization of a novel mouse epidermal differentiation gene and its promoter

The transcription factor E2F1 is an important regulator of cell proliferati on, apoptosis, and differentiation. A novel mouse gene (Eig3) was originall y identified as upregulated in E2F1-overexpressing keratinocytes by the rap id analysis of gene expression technique, An apparently full-length cDNA an d a 2.8-kb genomic fragment containing the entire gene have been cloned. Se quence comparisons suggest that Eig3 is homologous to a human epidermal dif ferentiation gene, XP5, and belongs to a family of at least 10 murine genes that are related to the small proline-rich genes involved in skin differen tiation. Eig3 was expressed in adult mouse stomach and epidermis and overex pressed in keratinocytes transgenic for E2F1 or E2F4, but not in c-myc tran sgenics. Interestingly, Eig3 expression was highly increased in mouse skin papillomas but not in squamous carcinomas, Since there is no E2F consensus binding sequence in the promoter or first intron of Eig3, E2F regulation ma y be indirect, (C) 2001 Academic Press.