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TGFβ1 rapidly activates Src through a non-canonical redox signaling mechanism

Hongqiao Zhang1, Kelvin J A Davies2, Henry Jay Forman3

  • 1Ethel Percy Andrus Gerontology Center, Leonard Davis School of Gerontology, The University of Southern California, United States.

Archives of Biochemistry and Biophysics
|January 14, 2015
PubMed

Insights

Transforming growth factor-β1 (TGF-β) activates Src in lung cancer cells via a non-canonical redox pathway. This involves increased hydrogen peroxide production and critical cysteine residues, bypassing traditional dephosphorylation.

Area of Science:

  • Cellular Biology
  • Molecular Signaling
  • Cancer Research

Background:

  • Transforming growth factor-β1 (TGF-β) signaling regulates cellular processes via Src activation.
  • Canonical Src activation involves pTyr530 dephosphorylation and Tyr419 auto-phosphorylation.
  • A non-canonical pathway involving cysteine oxidation has been proposed.

Purpose of the Study:

  • To investigate the mechanism of TGF-β-mediated Src activation in H358 small cell lung carcinoma cells.
  • To determine if canonical or non-canonical pathways are involved in TGF-β-induced Src activation.

Main Methods:

  • Treatment of H358 cells with TGF-β.
  • Analysis of Src phosphorylation at Tyr419 and Tyr530.
  • Inhibition studies using vanadate, GSH-ester, catalase, and apocynin.
  • Site-directed mutagenesis of critical cysteine residues in Src.

Main Results:

  • TGF-β increased Src Tyr419 phosphorylation and unexpectedly increased Tyr530 phosphorylation.
  • Vanadate treatment showed additive Src activation with TGF-β, indicating pTyr530 dephosphorylation is not required.
  • TGF-β induced transient extracellular H2O2 production, inhibited by GSH-ester and catalase.
  • Apocynin inhibited TGF-β-stimulated H2O2 production, implicating NADPH oxidase.
  • Mutations at Cys248, Cys277, Cys501 abrogated, and Cys490 reduced TGF-β-mediated Src activation.

Conclusions:

  • TGF-β-mediated Src activation in H358 cells primarily occurs through a redox-dependent mechanism.
  • This pathway involves NADPH oxidase-driven H2O2 production.
  • Cysteine residues 248, 277, 490, and 501 are crucial for this non-canonical activation.
Keywords:
Hydrogen peroxideOxidative modificationRedox signalingSrcTGF-β

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