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Different binding specificities and transactivation of variant CRE's by CREB complexes
1Department of Obstetrics and Gynecology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
Nucleic Acids Research
|April 25, 1994
Summary
This study reveals that DNA binding affinity of CREB complexes dictates gene transactivation. Sequence variations and flanking DNA significantly influence binding strength and subsequent gene expression levels.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- CREB (cAMP response element-binding protein) is a transcription factor crucial for gene regulation.
- Understanding the precise DNA binding specificities of CREB complexes is essential for deciphering gene expression control.
Purpose of the Study:
- To analyze the DNA binding specificities of CREB1 and CREB2 homodimers and the CREB2/cJun heterodimer.
- To investigate the relationship between DNA binding affinity and transactivation potential of CRE variants.
Main Methods:
- CASTing (Clamp-based Affinity Selection followed by Transformation) technique was employed to determine DNA binding specificities.
- Reporter gene assays in JEG-3 cells were used to measure transactivation levels.
Main Results:
- Each CREB complex exhibited unique DNA binding profiles with variations from the consensus CRE sequence.
- DNA binding affinities were influenced more by flanking sequences than the palindromic nature of the CRE.
- In vitro binding strength correlated with in vivo transactivation, especially for hybrid CREB proteins.
Conclusions:
- Transcription factor binding strength is a major determinant of DNA sequence element transactivation.
- Specific DNA sequences and their flanking regions can modulate the level of gene induction by CREB complexes.