Chromosoma

, Volume 111, Issue 2, pp 80–95

Pim-1 associates with protein complexes necessary for mitosis

  • Nandini Bhattacharya
  • Zeping Wang
  • Christine Davitt
  • Ian F. McKenzie
  • Pei-xiang Xing
  • Nancy S. Magnuson
Original Article

DOI: 10.1007/s00412-002-0192-6

Cite this article as:
Bhattacharya, N., Wang, Z., Davitt, C. et al. Chromosoma (2002) 111: 80. doi:10.1007/s00412-002-0192-6

Abstract.

The proto-oncogene pim-1 is a serine/threonine kinase the over-expression of which promotes lymphoma formation. Neither the normal function of Pim-1 nor the biochemical mechanism for cancer development mediated by the gene has been delineated, although recent studies have provided compelling evidence that Pim-1 is involved in differentiation and cell survival. We now provide the first evidence that Pim-1 may be involved in the proliferative process. By confocal microscopy, we observed a dynamic redistribution of Pim-1 during the cell cycle, the protein moving from the nucleus and cytoplasm in interphase to the spindle poles during mitosis. From a computer search for putative substrates of Pim-1 that are located in the spindle poles, we discovered that the nuclear mitotic apparatus (NuMA) protein has two peptide sequences that contain preferred phosphorylation sites for Pim-1 kinase. Recombinant glutathione-S-transferase-Pim-1 also readily phosphorylates immunoprecipitated NuMA. By confocal microscopy and co-immunoprecipitation we showed the interaction of the Pim-1 and NuMA proteins in HeLa cells that had been arrested during mitosis with nocodazole. Pim-1 also appeared to interact with heterochromatin-associated protein 1β (HP1β) and the cytoplasmic proteins dynein and dynactin via complex formation with NuMA. In our studies, overexpressed wild-type-Pim-1-GFP (green fluorescent protein) fusion protein was found to co-localize in the spindle pole with NuMA during mitosis. In contrast, the 'kinase-dead' mut-Pim-1-GFP fusion protein did not co-localize with NuMA, and appeared to promote apoptosis. Further evidence for apoptotic cell death was the observed blebbing and fragmentation of the chromosomes and a decrease in the level of NuMA protein detected by confocal microscopy. These results strongly suggest that Pim-1 kinase plays a role, most likely by phosphorylation, in promoting complex formation between NuMA, HP1β, dynein and dynactin, a complex that is necessary for mitosis.

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Nandini Bhattacharya
    • 1
  • Zeping Wang
    • 1
  • Christine Davitt
    • 2
  • Ian F. McKenzie
    • 4
  • Pei-xiang Xing
    • 4
  • Nancy S. Magnuson
    • 1
  1. 1.School of Molecular Biosciences, WSU, Pullman, WA 99164-4234, USA
  2. 2.The Electron Microscopy Center, School of Biological Sciences, WSU, Pullman, WA 99164-4234, USA
  3. 3.Cancer Prevention and Research Center, WSU, Pullman, WA 99164-4234, USA
  4. 4.The Austin Research Institute, Victoria, Australia

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