INTRACELLULAR DYNAMICS OF C-MYC MESSENGER-RNA TRAFFIC IN SINGLE CELLSIN-SITU

Processing and intracellular transport of RNA transcripts are essentia l for gene expression. Translational regulation of gene expression may occur by several mechanisms, including control of transcript movement from sites of synthesis to site(s) of translation. We describe tempor al analysis of the intracellular translocation of c-myc transcripts fr om the sire of synthesis in the nucleus to sites of translation in the cytoplasm. Fluorescence in situ hybridization (FISH) and quantitative fluorescence microscopy were used to measure intracellular traffic of c-myc transcripts in individual recombinant cells following activatio n of c-myc sequences linked to a heat shock promoter. C-myc nuclear tr anscripts are visible in the nucleus within minutes of heat exposure. Transcripts remain in the nucleus for at least 4 hr after gene activat ion. Transport of c-myc transcripts to the cytoplasm begins similar to 1 hr after cells are returned to 37 degrees C, These data demonstrate the feasibility of measuring intracellular transcript transport follo wing gene activation and provide a description of the kinetics of intr acellular traffic of inducible c-myc transcripts in heated cells in si tu.