First published online August 11, 2005
Development 132, 1703e (2005)
© The Company of Biologists Limited
The dynamics of PcG repression
During development, Polycomb group (PcG) proteins maintain patterns of gene
repression that are mediated by homeobox-containing proteins. These PcG
chromatin-binding proteins form several multicomponent complexes, but how
these repress gene transcription in vivo is unknown. Ficz and colleagues now
report that PcG protein complexes exchange rapidly, most within 2 minutes, in
living Drosophila embryos, which suggests that PcG repression occurs
through dynamic competition with other chromatin-binding proteins (see
p. 3963). By using
fluorescence recovery after photobleaching (FRAP) microscopy, the researchers
determined the kinetic properties of two PcG-GFP fusion proteins in whole
Drosophila embryos, wing imaginal discs and salivary glands. They
show that PcG complexes are rapidly exchanged throughout development and that
complexes at different chromosomal sites have different exchange rates. Thus,
PcG complexes maintain the long-term repression of developmental regulatory
genes dynamically rather than by statically limiting the access of
transcriptional activators to chromatin.
Related articles in Development:
- Polycomb group protein complexes exchange rapidly in living Drosophila
- Gabriella Ficz, Rainer Heintzmann, and Donna J. Arndt-Jovin
Development 2005 132: 3963-3976.
[Abstract]
[Full Text]
