Physical interaction of the activator protein-1 factors c-Fos and c-Jun with Cbfa1 for collagenase-3 promoter activation

Richard C. D'Alonzo, Nagarajan Selvamurugan, Gerard Karsenty, Nicola C. Partridge

Research output: Contribution to journalArticle

Abstract

Previously, we determined that the activator protein-1 (AP-1)-binding site and the runt domain (RD)-binding site and their binding proteins, c-Fos·c-Jun and Cbfa, regulate the collagenase-3 promoter in parathyroid hormone-treated and differentiating osteoblasts. Here we show that Cbfa1 and c-Fos·c-Jun appear to cooperatively bind the RD- and AP-1-binding sites and form ternary structures in vitro. Both in vitro and in vivo co-immunoprecipitation and yeast two-hybrid studies further demonstrate interaction between Cbfa1 with c-Fos and c-Jun in the absence of phosphorylation and without binding to DNA. Additionally, only the runt domain of Cbfa1 was required for interaction with c-Jun and c-Fos. In mammalian cells, overexpression of Cbfa1 enhanced c-Jun activation of AP-1-binding site promoter activity, demonstrating functional interaction. Finally, insertion of base pairs that disrupted the helical phasing between the AP-1- and RD-binding sites also inhibited collagenase-3 promoter activation. Thus, we provide direct evidence that Cbfa1 and c-Fos·c-Jun physically interact and cooperatively bind the AP-1- and RD-binding sites in the collagenase-3 promoter. Moreover, the AP-1- and RD-binding sites appear to be organized in a specific required helical arrangement that facilitates transcription factor interaction and enables promoter activation.

Original languageEnglish (US)
Pages (from-to)816-822
Number of pages7
JournalJournal of Biological Chemistry
Volume277
Issue number1
DOIs
StatePublished - Jan 4 2002

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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