Synthesis, processing, and transport of RNA within the three-dimensional context of the cell nucleus.

Fluorescence in situ hybridization and immunocytochemical techniques have contributed significantly to our current understanding of how transcription, RNA processing, and RNA transport are spatially and temporally organized in the cell nucleus. New technologies enabling the visualization of nuclear components in living cells specifically advanced our knowledge of the dynamic aspects of these nuclear processes. The picture that emerges from the work reviewed here shows that the positioning of genes within the three-dimensional nuclear space is of crucial importance, not only for its expression, but also for the efficient processing of its transcripts. Splicing factors are recruited from speckles to sites of active transcription, which can be present within, at the periphery, or at a relatively large distance from speckles. Furthermore, results are discussed showing that transcripts are exported by means of random diffusion.