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Ras-activated RSK1 phosphorylates EBP50 to regulate its nuclear localization and promote cell proliferation

Hooi Cheng Lim1, Tzuu-Shuh Jou1,2

  • 1Graduate Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan.

Oncotarget
|February 11, 2016
PubMed

Insights

The kinase RSK1 uniquely transports EBP50 to the nucleus by phosphorylating it at T156. This nuclear EBP50 promotes cancer, offering a potential therapeutic target.

Area of Science:

  • Molecular Biology
  • Cancer Biology
  • Cell Signaling

Background:

  • EBP50's role in cancer is debated, depending on its subcellular location (membrane vs. nucleus).
  • The mechanism driving EBP50's nuclear import, crucial for its oncogenic function, is unknown.

Purpose of the Study:

  • To elucidate the molecular mechanism responsible for EBP50's nuclear localization.
  • To identify key regulators of EBP50 nuclear transport in the context of cancer biology.

Main Methods:

  • RNA interference screening to identify factors involved in EBP50 nuclear transport.
  • Biochemical assays to study RSK1-EBP50 interaction and phosphorylation.
  • Site-directed mutagenesis to investigate the role of T156 phosphorylation.

Main Results:

  • RSK1 was identified as a unique mediator of EBP50 nuclear transport.
  • RSK1 phosphorylates EBP50 at threonine 156 (T156) in a growth factor-dependent manner.
  • T156 phosphorylation is essential for EBP50 nuclear localization, cell proliferation, and oncogenic transformation.

Conclusions:

  • RSK1-mediated phosphorylation of EBP50 at T156 drives its nuclear accumulation.
  • Aberrant nuclear EBP50 contributes to cancer development, suggesting it as a therapeutic target.
  • Targeting nuclear EBP50 may offer a strategy to treat cancer without disrupting normal EBP50 functions.
Keywords:
EBP50RSK1nuclear localizationphosphorylationproliferation

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