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CacyBP/SIP binds ERK1/2 and affects transcriptional activity of Elk-1

Ewa Kilanczyk1, Slawomir Filipek, Beata Jastrzebska

  • 1Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.

Biochemical and Biophysical Research Communications
|January 27, 2009
PubMed

Insights

Mouse CacyBP/SIP binds to ERK1/2, a protein interaction potentially regulated by S100A6. This binding impacts Elk-1 transcription factor phosphorylation, suggesting a novel regulatory pathway.

Area of Science:

  • Cellular signaling pathways
  • Protein-protein interactions
  • Molecular biology

Background:

  • Extracellular signal-regulated kinases (ERK1/2) are crucial in cellular signaling.
  • CacyBP/SIP is a protein involved in various cellular processes.
  • S100A6 is a calcium-binding protein that participates in signaling pathways.

Purpose of the Study:

  • To investigate the interaction between CacyBP/SIP and ERK1/2.
  • To determine the role of S100A6 in this interaction.
  • To elucidate the functional consequences of CacyBP/SIP-ERK1/2 binding on Elk-1 phosphorylation.

Main Methods:

  • Co-immunoprecipitation assays to confirm protein interactions.
  • Site-directed mutagenesis to create CacyBP/SIP mutants.
  • Molecular modeling to analyze binding interfaces.
  • In vitro and cellular assays to assess Elk-1 phosphorylation.

Main Results:

  • Mouse CacyBP/SIP directly interacts with ERK1/2.
  • S100A6 competes with ERK1/2 for binding to CacyBP/SIP in a calcium-dependent manner.
  • An E217K mutation in CacyBP/SIP abolishes ERK1/2 binding but retains S100A6 interaction.
  • Molecular modeling suggests electrostatic interactions mediate CacyBP/SIP-ERK1/2 binding.
  • CacyBP/SIP-ERK1/2 interaction inhibits Elk-1 phosphorylation in vitro and in NB2a cells.

Conclusions:

  • CacyBP/SIP binds to ERK1/2, modulating Elk-1 phosphorylation and transcriptional activity.
  • S100A6 acts as a negative regulator by competing with ERK1/2 for CacyBP/SIP binding.
  • This interaction represents a novel regulatory mechanism in cellular signaling.

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