[Gene expression by addictive drugs and drug dependence]

Drug dependence is developed by repeated administration of addictive drugs. This phenomenon resembles to learning and memory, although input stimuli are different. Pur alpha is abundant in the brain and binds to a single stranded DNA with (GGN)n sequence. The DNA-binding activity was enhanced by calmodulin and decreased in the brain treated with chronic morphine. The data suggest that morphine stimulates gene expression by a pathway different from that of cAMP. Arc protein is an "effector protein" and markedly induced by convulsion or methamphetamine. A novel protein, Amida, was isolated as an Arc-binding protein. Amida was transported into the nuclei and induced apoptosis and the inhibition of cell growth. The functions of these protein and the involvement of them in the development of drug dependence were discussed.