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Updated: Jul 18, 2026
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Visualization and Quantification of TGFβ/BMP/SMAD Signaling under Different Fluid Shear Stress Conditions using Proximity-Ligation-Assay
Published on: September 14, 2021
Systems theory of Smad signalling
D C Clarke1, M D Betterton, X Liu
1Department of Chemistry and Biochemistry , University of Colorado-Boulder, Boulder, CO 80309, USA.
Systems Biology
|December 26, 2006
Summary
Transforming growth factor-beta (TGFbeta) signaling relies on Smad proteins. Mathematical modeling reveals that unbalanced phosphorylation and dephosphorylation rates of Smad proteins are key to their nuclear accumulation during TGFbeta signaling.
Area of Science:
- Cellular biology
- Molecular signaling
- Mathematical modeling
Background:
- Transforming growth factor-beta (TGFbeta) signaling regulates cellular processes via Smad proteins.
- Smad proteins translocate to the nucleus to control gene transcription upon TGFbeta stimulation.
Purpose of the Study:
- To investigate the mechanisms governing Smad nuclear accumulation.
- To develop a mathematical model of canonical Smad signaling.
Main Methods:
- Constructed a mathematical model using published data and experimental Smad concentrations (Smad2, Smad3, Smad4).
- Analyzed model sensitivity to various parameters and performed statistical analysis.
- Simulated Smad nuclear accumulation with and without Smad4.
Main Results:
- Smad2 and Smad4 were present in higher cellular concentrations than Smad3 in mink lung epithelial cells.
- Smad nuclear accumulation is highly sensitive to R-Smad phosphorylation/dephosphorylation rates and nuclear complex dynamics.
- Rate-limiting phospho-R-Smad dephosphorylation emerged as a critical factor for Smad nuclear accumulation.
Conclusions:
- An imbalance in R-Smad phosphorylation and dephosphorylation rates is a likely driver of Smad nuclear accumulation in TGFbeta signaling.
- Constitutive nuclear binding factors are inefficient in mediating Smad nuclear accumulation if dephosphorylation is rapid.
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