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Dpc4 transcriptional activation and dysfunction in cancer cells
J L Dai1, K K Turnacioglu, M Schutte
1Department of Oncology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205-2196, USA.
Cancer Research
|October 27, 1998
Summary
Transforming growth factor beta (TGF-β) signaling relies on Dpc4 (Smad4) for gene regulation. Mutations in DPC4 impair this TGF-β-stimulated response, impacting tumor development.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- Dpc4 (Smad4) is crucial for mediating signals from transforming growth factor beta (TGF-β) and related ligands.
- Wild-type Dpc4 regulates TGF-β-stimulated gene transcription via Smad binding elements (SBEs).
Purpose of the Study:
- To characterize DPC4 tumor mutations and their impact on TGF-β signaling.
- To understand the mechanisms by which DPC4 mutations affect SBE-mediated gene regulation.
Main Methods:
- Analysis of DPC4 tumor mutations and cancer cell lines.
- Assessing DNA binding and transcriptional regulation functions of DPC4 mutants.
- Utilizing a nuclear localization domain to restore Dpc4 function.
Main Results:
- NH2-terminal DPC4 mutations disrupt DNA binding, impairing SBE-mediated gene regulation.
- COOH-terminal DPC4 mutations abolish transcriptional regulation while retaining DNA binding.
- Restoring Dpc4 nuclear localization rescued SBE-mediated transactivation in specific mutants and cell lines.
Conclusions:
- Loss of SBE-mediated gene regulation is a common outcome of DPC4 alterations in tumorigenesis.
- Targeted nuclear redistribution of Dpc4 may restore transcriptional events in cancer cells.