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Slow, stochastic transgene repression with properties of a timer
Clifford L Wang1, Desirée C Yang, Matthias Wabl
1Department of Microbiology and Immunology, University of California, San Francisco, CA 94143-0414, USA. cliff.wang@ucsf.edu
Genome Biology
|June 13, 2006
Summary
Stochastic gene repression in retroviral vectors can reflect genomic characteristics. This study identified heritably repressed cell clones, revealing an epigenetic mechanism for long-term gene silencing.
Area of Science:
- Molecular Biology
- Epigenetics
- Genomics
Background:
- Gene expression variability in genetically identical organisms is often termed stochastic.
- Retroviral vector integration can lead to stochastic gene repression, complicating outcome interpretation.
- Such repression may accurately reflect specific genomic site characteristics.
Purpose of the Study:
- To investigate heritable and irreversible gene repression mediated by retroviral vectors.
- To characterize the dynamics and kinetics of this repression process.
- To explore the potential role of such mechanisms in endogenous gene regulation.
Main Methods:
- Generation and identification of cell clones exhibiting stable retroviral transgene repression.
- Observation of repression dynamics over extended periods (months).
- Analysis of repression kinetics and reproducibility at specific genomic locations (e.g., mouse chromosome 9).
Main Results:
- Identified cell clones with heritable and near-irreversible retroviral transgene repression.
- Repression dynamics were observed to be ergodic, reaching a final state irrespective of prior conditions.
- Repression kinetics varied by genomic position, with near first-order kinetics observed on mouse chromosome 9, demonstrating high reproducibility.
Conclusions:
- Propose a cell division-independent 'off' mechanism for gene silencing.
- Suggest this epigenetic mechanism could function as a timer for extended periods in endogenous gene expression.