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Tyrosine-phosphorylated SOCS3 interacts with the Nck and Crk-L adapter proteins and regulates Nck activation

John C Sitko1, Claudia I Guevara, Nicholas A Cacalano

  • 1Department of Radiation Oncology, University of California Los Angeles, School of Medicine, Center for Health Sciences, Los Angeles, California 90095, USA.

The Journal of Biological Chemistry
|June 3, 2004
PubMed

Insights

Suppressors of cytokine signaling (SOCS3) interact with adapter proteins Nck and Crk-L. This interaction regulates multiple signaling pathways, revealing a new role for SOCS3 beyond the Jak-STAT pathway.

Area of Science:

  • Cellular signaling
  • Molecular biology
  • Signal transduction

Background:

  • Suppressors of cytokine signaling (SOCS) proteins are negative regulators of cytokine and growth factor signaling.
  • While their role in the Jak-STAT pathway is established, their function in other signaling pathways remains unclear.

Purpose of the Study:

  • To investigate the role of SOCS3 in regulating signaling pathways beyond Jak-STAT.
  • To identify novel protein interactions and mechanisms of SOCS3 action.

Main Methods:

  • Co-immunoprecipitation assays to detect protein interactions.
  • Site-directed mutagenesis to identify key phosphorylation sites and binding domains.
  • Expression of SOCS3 and Nck-GFP fusion proteins in NIH3T3 cells.

Main Results:

  • SOCS3 physically interacts with adapter proteins Nck and Crk-L.
  • This interaction is dependent on tyrosine phosphorylation of SOCS3 at Tyr(221) and intact SH2 domains of Nck and Crk-L.
  • SOCS3 Tyr(221) forms a YXXP motif, a binding site for Nck and Crk-L SH2 domains.
  • SOCS3 expression leads to constitutive recruitment of Nck to the plasma membrane and Nck tyrosine phosphorylation.

Conclusions:

  • SOCS3 acts as a recruitment factor for Nck and Crk-L adapter proteins.
  • SOCS3 regulates multiple signaling pathways by interacting with these adapter proteins.
  • This study expands the known functions of SOCS3 in cellular signaling.

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