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DNA tetraplex formation in the control region of c-myc
T Simonsson1, P Pecinka, M Kubista
1Department of Biochemistry, Lundberg Institute, Chalmers University of Technology, Medicinaregatan 9C, SE-413 90 Goteborg, Sweden. tomas@bcbp.chalmers.se
Abstract:
The c-myc oncogene is one of the most commonly malfunctioning genes in human cancers, and is an attractive target for anti-gene therapy. Although synthetic oligonucleotides designed to silence c-myc expression via one of its major control elements function well in vitro, their mode of action has been indefinite. Here we show that the targeted control element adopts an intrastrand fold-back DNA tetraplex, which requires potassium ions for stability in vitro. We believe formation of the tetraplex is important for c-myc activation in vivo, and propose a transcription initiation mechanism that explains how anti-gene therapy silence c-myc at the molecular level.
Insights
The c-myc oncogene, crucial in cancer, can be targeted by anti-gene therapy. This study reveals a DNA tetraplex structure essential for c-myc activation and silencing.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- The c-myc oncogene is frequently altered in human cancers.
- c-myc is a significant target for anti-gene therapy strategies.
- The precise mechanism of action for anti-c-myc oligonucleotides remains unclear.
Purpose of the Study:
- To elucidate the molecular mechanism by which anti-gene therapy silences c-myc expression.
- To identify the structural basis of c-myc gene regulation at a key control element.
- To propose a model for transcription initiation involving DNA tetraplex formation.
Main Methods:
- In vitro analysis of DNA structure using synthetic oligonucleotides targeting c-myc.
- Investigation of DNA fold-back tetraplex formation.
- Assessment of potassium ion dependency for tetraplex stability.
- Development of a molecular model for c-myc transcription initiation.
Main Results:
- A specific control element of c-myc forms an intrastrand fold-back DNA tetraplex structure.
- Potassium ions are critical for the stability of this DNA tetraplex in vitro.
- The tetraplex structure is hypothesized to play a role in c-myc activation in vivo.
Conclusions:
- The formation of a potassium-dependent DNA tetraplex is a key feature of a c-myc control element.
- This tetraplex structure is proposed to be important for c-myc gene activation.
- Understanding this mechanism provides insight into how anti-gene therapies can silence c-myc.