DAMAGE TO DNA BY UV-LIGHT AND ACTIVATION OF TRANSCRIPTION FACTORS

Bacteria react to irradiation with short wave length UV (UVC) by mount ing a rescuing response which involves the synthesis of proteins engag ed in DNA repair, replication and mutagenesis. We analyse here an anal ogous response shown by mammalian cells in culture and present experim ental 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 c omponents located at the plasma membrane, such as src, ras and raf. Th ese components, upon activation by UV, signal into the cell's nucleus, thereby activating transcription factors which control the activity o f UV responsive genes.