DETECTION OF LIVING CELLS THAT EXPRESS AP1 USING A FLUOROLABELED DNA-PROBE

Activator protein 1 (API) is a complex of Fos and Jun, and it regulate s the transcription of genes possessing the AP1-binding sequence. The purpose of this study was to detect living cells that express AP1 afte r stimulation with a tumor promoter, The Fos and Jun components of AP1 were induced rapidly and transiently in PC12 cells following the addi tion of phorbol ester (phorbol 12-myristate 13-acetate, PMA). The DNA fragment containing the AP1-binding sequence was combined with ethidiu m bromide, which was used as a fluorescent probe, The probe was transf ected into the cells using cationic liposomes. Fluorescence in the tra nsfected cells was observed using a fluorescence microscope. The nucle i of transfected cells emitted strong fluorescence in the presence of PMA, whereas weak fluorescence was retained in the cytoplasm in its ab sence, The former phenomenon is evidence that AP1 combined with the fl uorescent probe was transported into the nuclei. This study suggests t hat such a fluorolabeling method is feasible to detect living AP1-expr essed neurons.