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Live Cell Imaging of the TGF- β/Smad3 Signaling Pathway In Vitro and In Vivo Using an Adenovirus Reporter System
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Convergence of transforming growth factor-beta and vitamin D signaling pathways on SMAD transcriptional coactivators

J Yanagisawa1, Y Yanagi, Y Masuhiro

  • 1Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.

Science (New York, N.Y.)
|February 26, 1999
PubMed

Insights

Transforming growth factor-beta (TGF-beta) and vitamin D signaling pathways interact. Smad3 protein acts as a bridge, mediating cross-talk between these crucial cell growth regulators.

Area of Science:

  • Cell biology
  • Molecular signaling
  • Endocrinology

Background:

  • Cell proliferation and differentiation are key processes regulated by growth factors like transforming growth factor-beta (TGF-beta) and vitamin D.
  • TGF-beta signaling involves SMAD proteins, which function as nuclear coactivators or transcription factors.
  • Vitamin D regulates gene transcription via the vitamin D receptor (VDR).

Purpose of the Study:

  • To investigate the potential cross-talk between TGF-beta and vitamin D signaling pathways.
  • To elucidate the role of SMAD proteins in mediating the effects of vitamin D.

Main Methods:

  • Mammalian cell culture.
  • Analysis of protein-protein interactions in the nucleus.
  • Assessment of transcriptional coactivation of the vitamin D receptor (VDR).

Main Results:

  • Smad3, a downstream SMAD protein in the TGF-beta pathway, was identified as a coactivator for ligand-induced VDR transactivation.
  • Smad3 forms a nuclear complex with steroid receptor coactivator-1 (SRC-1) family members to facilitate VDR activity.
  • This interaction is specific to ligand-induced VDR transactivation.

Conclusions:

  • Smad3 mediates cross-talk between TGF-beta and vitamin D signaling pathways.
  • The findings reveal a novel mechanism linking TGF-beta and vitamin D actions in mammalian cells.
  • This cross-talk may play a significant role in regulating cell proliferation and differentiation.

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