CELLULAR-RESPONSES TO GENOTOXIC AGENTS - DNA-REPAIR, ACTIVATION OF TRANSCRIPTION, CELL-CYCLE ARREST AND APOPTOSIS

Cellular responses to genotoxic agents can be classified either as act ive or passive. Passive responses include the inhibition of transcript ion and DNA replication which initially result from the fact that many DNA lesions block the progression of RNA and DNA polymerases. Active responses include DNA repair, transcriptional activation of specific g enes, cell cycle arrest and apoptosis. We provide examples to illustra te these different active responses to genotoxic agents and we address the question of the nature of the signal that activates these respons es. Our data indicate that DNA repair plays a key role in the activati on of transcription.