Chromosoma

, Volume 108, Issue 4, pp 220–234

Localization and phosphorylation of HP1 proteins during the cell cycle in mammalian cells

  • Elsa Minc
  • Yves Allory
  • Howard J. Worman
  • Jean-Claude Courvalin
  • Brigitte Buendia
Original articles

DOI: 10.1007/s004120050372

Cite this article as:
Minc, E., Allory, Y., Worman, H. et al. Chromosoma (1999) 108: 220. doi:10.1007/s004120050372

Abstract.

Mammalian heterochromatin proteins 1 (HP1α, HP1β, and HP1γ) are nonhistone proteins that interact in vitro with a set of proteins that play a role in chromatin silencing, transcription, and chromatin remodeling. Using antibodies specific for each HP1 isoform, we showed that they segregate in distinct nuclear domains of human HeLa cells. By contrast, in mouse 3T3 interphase cells, HP1α and HP1β are strictly colocalized. In mitotic HeLa cells, all of HP1α and a fraction of HP1β and HP1γ remain associated with chromosomes. Immunostaining of spread HeLa chromosomes showed that HP1α is mainly localized on centromeres as shown previously for HP1β, while HP1γ is distributed on discrete sites on the arms of chromosomes. Biochemical analysis showed that HP1α and HP1γ are phosphorylated throughout the cell cycle, although more extensively in mitosis than in interphase, while HP1β apparently remains unphosphorylated. Therefore, despite their extensive sequence conservation, mammalian HP1 isoforms differ widely in their nuclear localization, mitotic distribution and cell cycle-related phosphorylation. Thus, subtle differences in primary sequence and in posttranslational modifications may promote their targeting at different chromatin sites, generating pleiotropic effects.

Abbreviations. HP1 Heterochromatin protein 1Pc PolycombDAPI 4’6-diamidino-2-phenylindole

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Elsa Minc
    • 1
  • Yves Allory
    • 1
  • Howard J. Worman
    • 2
  • Jean-Claude Courvalin
    • 1
  • Brigitte Buendia
    • 1
  1. 1.Departement de Biologie Cellulaire, Institut Jacques Monod, CNRS, Université Paris 7, Paris, FranceFR
  2. 2.Departments of Medicine and of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY, USAUS