Damage to DNA by UV light and activation of transcription factors.

Bacteria react to irradiation with short wave length UV (UVC) by mounting a rescuing response which involves the synthesis of proteins engaged in DNA repair, replication and mutagenesis. We analyse here an analogous response shown by mammalian cells in culture and present experimental evidence for the chain of events induced by UV irradiation that leads to enhanced gene expression. Available results suggest that the UV induced signal cascade depends on damage to DNA and also involves components located at the plasma membrane, such as src, ras and raf. These components, upon activation by UV, signal into the cell's nucleus, thereby activating transcription factors which control the activity of UV responsive genes.