[초청강연] Topology of mammalian transcription

Topology of mammalian transcription

Won-Ki Cho

KAIST, Department of Biological Sciences

Mammalian genome is organized into a hierarchical structure at multiple scales in a cell nucleus.
At the most macroscopic scale, individual chromosomes are segregated into own separated
intranuclear regions, which is so called chromosome territories. On the other hand, recent
intensive studies using live-cell imaging techniques have characterized behaviors of subnuclear
compartments, exemplified with transcriptional condensates and nuclear speckles. They are
functionally specialized non-membrane bound organelles, mostly follow liquid properties.
However, how the genome structure and subnuclear organelles are spatially organized in the
nucleus has not been elucidated. We found that chromatin looping by CTCF, a chromatin
architectural protein, acts as an architectural prerequisite for the assembly of phase-separated
transcriptional condensates. Moreover, we observed a layered structure of transcriptional and
splicing condensates near the nuclear matrix discovered by super-resolution imaging of RNA
polymerase II, nuclear speckles, and Scaffold attachment factor A (SAF-A, a nuclear matrix
associated proteins).

Key words: Nucleus, Gene expression, Transcription, Chromatin, Transcriptional condensate,
Genome organization, Super-resolution, Live cell imaging