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Mind the gap; regulation of gap junctional, intercellular communication by the SRC oncogene product and its effectors

Mulu Geletu1, Aaron Trotman-Grant, Leda Raptis

  • 1Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L3N6.

Anticancer Research
|October 13, 2012
PubMed

Insights

Gap junctional intercellular communication (GJIC) is vital for normal cell growth. While Src kinase reduces GJIC by phosphorylating connexin 43 (Cx43), it does not require Stat3 activation, which actually maintains GJIC.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • Gap junctions, formed by connexin (Cx) proteins, facilitate intercellular communication (GJIC).
  • Reduced GJIC is linked to increased cell growth and neoplastic transformation.
  • Cx43, a key connexin, is regulated by phosphorylation and protein interactions.

Purpose of the Study:

  • To investigate the role of Src oncoprotein tyrosine kinase and its effectors in regulating Cx43 and GJIC.
  • To determine the involvement of Signal transducer and activator of transcription-3 (Stat3) in Src-mediated GJIC suppression.

Main Methods:

  • Analysis of Cx43 phosphorylation sites (tyr247, -265) by Src.
  • Investigation of Src signaling pathways (Ras/Raf/Erk, PLCγ/protein kinase C) affecting Cx43.
  • Assessment of the role of Src effector Cas in binding Cx43.
  • Evaluation of Stat3's requirement in Src-mediated GJIC suppression.

Main Results:

  • Src phosphorylation of Cx43 at tyr247 and -265 reduces GJIC.
  • Other Src pathways (Ras/Raf/Erk, PLCγ/PKC) also phosphorylate Cx43, disrupting communication.
  • Src effector Cas binds Cx43, further suppressing GJIC.
  • Stat3 activation is not required for Src-mediated GJIC suppression.

Conclusions:

  • Src kinase significantly impacts GJIC by modulating Cx43 through various mechanisms.
  • Stat3 plays a contrasting role, being essential for maintaining GJIC in normal cells.
  • Understanding these pathways offers insights into cancer development and potential therapeutic targets.

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