Related Experiment Video
Updated: Jul 5, 2026

Live Cell Imaging of the TGF- β/Smad3 Signaling Pathway In Vitro and In Vivo Using an Adenovirus Reporter System
Published on: July 30, 2018
Cyclin-dependent kinases regulate the antiproliferative function of Smads
Isao Matsuura1, Natalia G Denissova, Guannan Wang
1Center for Advanced Biotechnology and Medicine,Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
Cyclin-dependent kinases (CDKs) phosphorylate Smad3, inhibiting its growth-suppressing activity. This CDK-mediated inhibition of Smad3 may drive cancer development and resistance to transforming growth factor-beta (TGF-beta).
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Transforming growth factor-beta (TGF-beta) is a potent inhibitor of cell cycle progression.
- Smad3 is a critical mediator of TGF-beta's growth-inhibitory effects.
- The regulation of Smad3 activity by cell cycle machinery is not fully understood.
Purpose of the Study:
- To investigate the role of G1 cyclin-dependent kinases (CDKs) in regulating Smad3 function.
- To identify and characterize the sites of CDK phosphorylation on Smad3.
- To determine the impact of Smad3 phosphorylation on its antiproliferative activity and role in TGF-beta signaling.
Main Methods:
- Phosphorylation site mapping of Smad3 by CDK4 and CDK2.
- Site-directed mutagenesis of identified CDK phosphorylation sites in Smad3.
- Analysis of Smad3 transcriptional activity, p15 and c-myc expression.
- Cell cycle progression assays using Smad3-deficient cells and cell lines with mutated Smad3.
Main Results:
- Smad3 is identified as a major physiological substrate for CDK4 and CDK2, with specific phosphorylation sites mapped at Thr 8, Thr 178, and Ser 212.
- Mutating these CDK phosphorylation sites enhances Smad3's transcriptional activity, leading to increased expression of the CDK inhibitor p15 and decreased expression of c-myc.
- Smad3 phosphorylation by CDKs impairs its ability to inhibit cell cycle progression from G1 to S phase.
Conclusions:
- CDK-mediated phosphorylation of Smad3 inhibits its transcriptional activity and antiproliferative function.
- This inhibitory mechanism may contribute to uncontrolled cell proliferation in cancer.
- Dysregulation of Smad3 activity by CDKs could be a mechanism underlying resistance to TGF-beta signaling in various cancers.
More Related Videos
06:54Studying TGF-β Signaling and TGF-β-induced Epithelial-to-mesenchymal Transition in Breast Cancer and Normal Cells
Published on: October 27, 2020
11:38Visualization and Quantification of TGFβ/BMP/SMAD Signaling under Different Fluid Shear Stress Conditions using Proximity-Ligation-Assay
Published on: September 14, 2021
Related Concept Videos
mTOR Signaling and Cancer Progression
The mTOR pathway or the...
Interactions Between Signaling Pathways
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Amplifying Signals via Enzymatic Cascade
The JAK-STAT Signaling Pathway
TGF - β Signaling Pathway
cAMP-dependent Protein Kinase Pathways