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Updated: Jun 29, 2026

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Published on: October 27, 2020
Lkb1 is required for TGFbeta-mediated myofibroblast differentiation
Kari Vaahtomeri1, Eeva Ventelä, Kaisa Laajanen
1Genome-Scale Biology Program, Institute of Biomedicine, Biomedicum Helsinki, P.O. Box 63, 00014 University of Helsinki, Finland.
Loss of the tumor suppressor LKB1 (liver kinase B1) in mesenchymal cells impairs TGF-beta signaling, leading to defective myofibroblast differentiation and potentially contributing to Peutz-Jeghers syndrome (PJS) tumorigenesis.
Area of Science:
- Cell Biology
- Oncology
- Molecular Biology
Background:
- Peutz-Jeghers syndrome (PJS) is linked to inactivating mutations in the tumor suppressor gene LKB1.
- PJS polyps exhibit a distinct smooth-muscle and stromal component.
- Lkb1 deletion in specific mesenchymal cells induces PJS-type polyps in mice.
Purpose of the Study:
- To investigate the stromal functions of LKB1 in tumor suppression.
- To elucidate the role of LKB1 in myofibroblast differentiation and TGF-beta signaling.
Main Methods:
- Ablation of LKB1 in primary mouse embryo fibroblasts (MEFs).
- Analysis of Smad activation and TGF-beta-dependent transcription.
- Assessment of myofibroblast differentiation, alpha-smooth muscle actin (SMA) stress fiber formation, and contractility.
- Evaluation of serum response factor (SRF) activity.
Main Results:
- LKB1 ablation in MEFs attenuated Smad activation and TGF-beta-dependent transcription.
- LKB1-deficient MEFs showed defective myofibroblast differentiation, reduced SMA-positive stress fibers, and decreased contractility.
- The differentiation defect was independent of SRF activity but rescued by exogenous TGF-beta, indicating impaired TGF-beta signaling.
Conclusions:
- LKB1 inactivation disrupts TGF-beta signaling, impairing myofibroblast differentiation.
- Defective myogenic differentiation in LKB1-deficient mesenchymal cells may contribute to PJS tumorigenesis.
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