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MyoD1 promoter autoregulation is mediated by two proximal E-boxes
J M Zingg1, G Pedraza-Alva, J P Jost
1Friedrich Miescher Institut, Basel, Switzerland.
Nucleic Acids Research
|June 25, 1994
Summary
The MyoD1 gene in mouse myoblasts is controlled by a positive feedback loop, with MyoD1 protein directly binding to its promoter. This autoregulation is hindered by negative regulators and DNA methylation, except in skeletal muscle.
Area of Science:
- Molecular Biology
- Gene Regulation
- Muscle Development
Background:
- MyoD1 is a key transcription factor for skeletal muscle differentiation.
- Understanding MyoD1 gene regulation is crucial for muscle development research.
Purpose of the Study:
- To investigate the autoregulation mechanism of the MyoD1 promoter.
- To identify the regulatory elements involved in MyoD1 gene expression.
- To explore the influence of negative regulators and DNA methylation on MyoD1 autoregulation.
Main Methods:
- Deletion and mutation analyses of the MyoD1 promoter.
- Gel mobility shift competition assays.
- Transfection studies in mouse myoblasts and fibroblasts.
- DNA methylation analysis.
Main Results:
- MyoD1 expression stimulates its own promoter via a positive feedback loop.
- Two proximal E-boxes on the MyoD1 promoter are direct targets for MyoD1 protein binding.
- Autoregulation is impaired in fibroblasts, potentially due to inhibitory proteins like Id.
- DNA methylation density inversely affects MyoD1 promoter accessibility and autoregulation.
- The MyoD1 promoter is demethylated in skeletal muscle but methylated in other tissues.
Conclusions:
- MyoD1 autoregulation is a critical mechanism for high-level gene expression.
- Negative regulatory factors and DNA methylation act as constraints on MyoD1 autoregulation.
- Demethylation of the MyoD1 promoter in skeletal muscle likely facilitates its activation and muscle differentiation.