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Nuclear factor I can functionally replace transcription factor Sp1 in a U2 small nuclear RNA gene enhancer
L Janson1, P Weller, U Pettersson
1Department of Medical Genetics, Uppsala University, Biomedical Center, Sweden.
Journal of Molecular Biology
|January 20, 1989
Summary
Investigating the U2 small nuclear RNA gene, this study reveals a cooperative interaction between transcription factors Sp1 and octamer-binding factor. This interplay is crucial for gene activation and can involve nuclear factor I (NFI) as a substitute for Sp1.
Area of Science:
- Molecular Biology
- Gene Regulation
- Transcription Factor Interactions
Background:
- Human U2 small nuclear RNA (snRNA) gene transcription relies on a proximal sequence element and a distal enhancer.
- The U2 enhancer contains binding sites for Sp1 and octamer-binding factors, crucial for Polymerase II activity.
Purpose of the Study:
- To investigate the functional interplay between Sp1 and octamer-binding factor sites within the U2 enhancer.
- To determine if the binding site arrangement is critical for cooperative transcription activation.
Main Methods:
- Transfection of U2 maxigene constructs into HeLa cells.
- Analysis of transcription factor interactions and their impact on gene expression.
Main Results:
- A non-additive cooperation was observed between the octamer-binding factor and Sp1, independent of binding site orientation.
- The Sp1-binding site was functionally replaceable by a nuclear factor I (NFI) binding site.
- Octamer-binding factor stimulated transcription with either Sp1 or NFI.
Conclusions:
- The octamer-binding factor (likely NFIII) and NFI form a complex that efficiently activates transcription.
- This NFI/NFIII complex, known for adenovirus DNA replication, also plays a role in transcriptional activation of human genes.