Loss of Drosophila Myb interrupts the progression of chromosome condensation

Nat Cell Biol. 2007 May;9(5):581-7. doi: 10.1038/ncb1580. Epub 2007 Apr 22.


Completion of chromosome condensation is required before segregation during the mitotic cell cycle to ensure the transmission of genetic material with high fidelity in a timely fashion. In many eukaryotes this condensation is regulated by phosphorylation of histone H3 on Ser 10 (H3S10). This phosphorylation normally begins in the late-replicating pericentric heterochromatin and then spreads to the earlier replicating euchromatin. Here, we show that these phases of condensation are genetically separable in that the absence of Drosophila Myb causes cells to arrest with H3S10 phosphorylation of heterochromatin but not euchromatin. In addition, we used mosaic analysis to demonstrate that although the Myb protein can be removed in a single cell cycle, the failure of chromosome condensation occurs only after many cell divisions in the absence of Myb protein. The Myb protein is normally located in euchromatic but not heterochromatic regions of the nucleus, suggesting that Myb may be essential for a modification of euchromatin that is required for the efficient spread of chromosome condensation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Nucleus / metabolism
  • Chromatin Assembly and Disassembly*
  • Chromosomes / metabolism*
  • Drosophila / embryology
  • Drosophila / genetics
  • Drosophila / physiology*
  • Drosophila Proteins / deficiency
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Euchromatin / metabolism
  • Heterochromatin / metabolism
  • Histones / metabolism
  • Larva / physiology
  • Mitosis / physiology*
  • Mutation
  • Phosphorylation
  • Proto-Oncogene Proteins c-myb / deficiency
  • Proto-Oncogene Proteins c-myb / genetics
  • Proto-Oncogene Proteins c-myb / metabolism*
  • Serine / metabolism


  • Cell Cycle Proteins
  • Drosophila Proteins
  • Euchromatin
  • Heterochromatin
  • Histones
  • Myb protein, Drosophila
  • Proto-Oncogene Proteins c-myb
  • Serine