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Cx43 mediates TGF-beta signaling through competitive Smads binding to microtubules

Ping Dai1, Takuo Nakagami, Hideo Tanaka

  • 1Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine, Kawaramachi Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. dping@koto.kpu-m.ac.jp

Molecular Biology of the Cell
|April 13, 2007
PubMed

Insights

Connexin43 (Cx43) positively regulates transforming growth factor-beta (TGF-beta) signaling. Cx43 releases Smad2/3 from microtubules, promoting nuclear accumulation and target gene activation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Transforming growth factor-beta (TGF-beta) superfamily members are crucial for cellular processes.
  • Microtubules (MTs) negatively regulate TGF-beta signaling by anchoring Smad2/3.
  • Connexin43 (Cx43) interacts with MTs and mediates TGF-beta activity.

Purpose of the Study:

  • To elucidate the mechanism of intracellular regulation of TGF-beta activity by Cx43.
  • To investigate the functional link between TGF-beta activation and Cx43 via Smad2/3 and MTs.

Main Methods:

  • Investigated interactions among Smad2/3, MTs, and Cx43.
  • Utilized double-strand RNA (dsRNA) to knock down Cx43 in HL1 cardiomyocytes.
  • Examined Cx43 knockout mice cardiomyocytes.

Main Results:

  • Cx43 competes with Smad2/3 for binding to MTs.
  • Cx43 induces Smad2/3 release from MTs, increasing phospho-Smad2 levels.
  • Smad2/3 and Smad4 accumulate in the nucleus, activating target gene transcription.

Conclusions:

  • Cx43 positively regulates TGF-beta function through a novel mechanism involving Smad2/3 and MTs.
  • Cx43's interaction with MTs is critical for TGF-beta pathway activation.

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