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RSK promotes G2/M transition through activating phosphorylation of Cdc25A and Cdc25B

C F Wu1, S Liu2, Y-C Lee3

  • 1Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.

Oncogene
|May 28, 2013
PubMed

Insights

Ribosomal S6 kinase (RSK) activates Cdc25A and Cdc25B, promoting cell cycle G2/M transition in mammalian cells. This RSK-mediated phosphorylation enhances M-phase-inducing activities, crucial for cell division.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The mitogen-activated protein kinase (MAPK) cascade regulates the G2/M cell cycle transition, but its precise molecular mechanisms are not fully understood.
  • Ribosomal S6 kinase (RSK) is a critical downstream effector of the MAPK pathway.
  • Previous research implicated RSK2 in Cdc25C activation during Xenopus oocyte maturation.

Purpose of the Study:

  • To elucidate the role of RSK in regulating the G2/M cell cycle transition in mammalian cells.
  • To investigate the phosphorylation of Cdc25 isoforms by RSK and its impact on M-phase-inducing activities.

Main Methods:

  • Utilized recombinant and endogenous RSK in Xenopus egg extracts to study Cdc25 phosphorylation.
  • Investigated RSK phosphorylation of human Cdc25 isoforms (Cdc25A, Cdc25B, Cdc25C) in HEK293 and PC-3mm2 cell lines.
  • Assessed the effect of RSK-mediated phosphorylation on Cdc25 M-phase-inducing activities and G2/M transition.

Main Results:

  • RSK phosphorylates human Cdc25A and Cdc25B at conserved motifs, enhancing their M-phase-inducing activities.
  • RSK activity is higher in mitotic cells compared to interphase cells, indicated by RSK phosphorylation status.
  • Inhibition of RSK-mediated Cdc25 phosphorylation impedes the G2/M cell cycle transition.

Conclusions:

  • RSK promotes G2/M transition in mammalian cells by phosphorylating and activating Cdc25A and Cdc25B.
  • RSK acts as a key regulator linking MAPK signaling to cell cycle progression through Cdc25 activation.

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