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Cell cycle-mediated structural and functional alteration of P85gag-mos protein kinase activity

J X Liu1, B Singh, D Wlodek

  • 1Department of Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston 77030.

Oncogene
|February 1, 1990
PubMed

Insights

Viral mos protein kinase activity increases during the cell cycle, peaking in mitosis. This regulation occurs via phosphorylation, suggesting mos protein affects multiple cellular targets.

Area of Science:

  • Molecular Biology
  • Virology
  • Cell Biology

Background:

  • The Moloney murine sarcoma virus encodes a P85gag-mos transforming protein with protein kinase activity.
  • Understanding the regulation of viral oncogenes during the cell cycle is crucial for cancer research.

Purpose of the Study:

  • To investigate the cell cycle-dependent regulation of viral mos protein kinase activity.
  • To determine how P85gag-mos protein kinase activity changes across different phases of the cell cycle.

Main Methods:

  • Utilized a temperature-sensitive mutant (ts110) of Moloney murine sarcoma virus in chronically infected normal rat kidney cells (NRK-6m2).
  • Employed elutriation experiments to separate cells based on cell cycle phase.
  • Synchronized mitotic cells using thymidine/colcemid or nocodazole treatments.

Main Results:

  • Observed a twofold increase in P85gag-mos protein kinase specific activity from G0/G1 through S and G2/M phases.
  • Detected a three- to fourfold increase in kinase activity in synchronized mitotic cells compared to unsynchronized cells.
  • Identified a structural alteration in the gag-mos protein in mitotic cells, resulting in a slower migrating species on SDS-polyacrylamide gels.

Conclusions:

  • Viral mos protein kinase activity is regulated during the cell cycle, primarily through phosphorylation.
  • The mos transforming protein likely functions in a pleiotropic manner, impacting both cytoplasmic and nuclear cellular targets.

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