Physical Interaction of the Activator Protein-1 Factors c-Fos and c-Jun with Cbfa1 for Collagenase-3 Promoter Activation
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Discussion
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Implication
In vitro study demonstrates physical interaction between Cbfa1 and AP-1 factors in bone cells, indicating helical spacing controls collagenase-3 activation.
Key Points
- To determine whether Cbfa1 physically interacts with the AP-1 transcription factors c-Fos and c-Jun to regulate collagenase-3 promoter activation.
- Assayed protein-DNA binding and ternary complex formation in vitro using DNA-binding assays.
- Performed in vitro and in vivo co-immunoprecipitation, yeast two-hybrid analyses, and domain-mapping studies without requiring protein phosphorylation or direct DNA binding.
- Evaluated mammalian cell promoter activation following Cbfa1 and c-Jun overexpression and tested structural sensitivity by inserting base pairs to disrupt helical phasing between binding sites.
- Cbfa1 directly interacted with both c-Fos and c-Jun in vitro and in vivo, mediated solely through the runt domain of Cbfa1.
- Cbfa1 and c-Fos/c-Jun cooperatively bound adjacent runt domain- and AP-1-binding sites to form ternary complexes, and Cbfa1 overexpression amplified c-Jun-mediated promoter activation in mammalian cells.
- Disrupting the helical phasing between the AP-1- and runt domain-binding sites via base pair insertions significantly impaired collagenase-3 promoter activation.
Cite This Study
DʼAlonzo et al. (2002) studied this question.