DDB1 is essential for genomic stability in developing epidermis.

The mammalian epidermis is maintained by proliferation and differentiation of epidermal progenitor cells in a stereotyped developmental program. Here we report that tissue-specific deletion of the UV-damaged DNA-binding protein 1 (DDB1) in mouse epidermis led to dramatic accumulation of c-Jun and p21Cip1, arrest of cell cycle at G(2)/M, selective apoptosis of proliferating cells, and as a result, a nearly complete loss of the epidermis and hair follicles. Deletion of the p53 tumor suppressor gene partially rescued the epithelial progenitor cells from death and allowed for the accumulation of aneuploid cells in the epidermis. Our results suggest that DDB1 plays an important role in development by controlling levels of cell cycle regulators and thereby maintaining genomic stability.