Identification of Ultraviolet-inducible Proteins That Bind to a TGACAACA Sequence in the Polyoma Virus Regulatory Region

The exposure of mammalian cells to UV light or other DNA-damaging agents induces several responses which may provide cellular defense mechanisms and also play a role in carcinogenesis. Employing a 257-base pair DNA fragment from the polyoma virus that contains the origin of replication and regulatory region of this virus, we have identified a set of DNA-binding proteins that are induced in normal rat fibroblasts at 6–24 h after UV exposure. These proteins bind to a specific octamer sequence (TGACAACA) designated the “UV response element.” Purification of these inducible proteins on a UV response element affinity column revealed a set of proteins, among which the major protein has a molecular weight of 40,000, which co-purify with c-fos but do not react with antibodies to c-jun-encoded proteins. These UV-induced proteins may, in concert with other cellular components, play a role in mediating specific cellular responses to DNA damage in mammalian cells.