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Cyclin A expression is under negative transcriptional control during the cell cycle
Molecular and Cellular Biology
|July 1, 1996
Summary
Researchers identified a key DNA sequence that controls cyclin A gene transcription, crucial for cell division. Modifying this element prevents repression, allowing continuous cell proliferation.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Cyclin A is essential for cell cycle progression, specifically S-phase transit.
- Its gene transcription is tightly regulated and occurs only in proliferating cells.
Purpose of the Study:
- To investigate the transcriptional regulation of the murine cyclin A gene.
- To identify regulatory elements controlling cell cycle-dependent gene expression.
Main Methods:
- Isolated and cloned the 5' flanking sequences of the murine cyclin A gene.
- Fused the promoter region to a luciferase reporter gene for functional assays.
- Utilized in vivo footprinting to identify protein-DNA interactions throughout the cell cycle.
Main Results:
- The cyclin A promoter is regulated by cell proliferation status.
- A conserved GC-rich element acts as a negative regulator, repressing transcription upon proliferation arrest.
- Mutation of this element leads to constitutive promoter activity.
- In vivo footprinting confirmed a cell cycle-responsive element (CRE) protected in G0/early G1 and differentiating cells, but not in proliferating cells.
Conclusions:
- The murine cyclin A gene transcription is negatively regulated by proliferation arrest via a specific GC-rich element.
- This element functions as a cell cycle-responsive element (CRE) that is bound by regulatory factors during specific cell cycle phases.
- Understanding this regulation provides insights into cell division control mechanisms.