Repression of AP-1 function: A mechanism for the regulation of Blimp-1 expression and B lymphocyte differentiation by the B cell lymphoma-6 protooncogene

Farha H. Vasanwala, Saritha Kusam, Lisa M. Toney, Alexander L. Dent

Research output: Contribution to journalArticle

132 Scopus citations


The B cell lymphoma-6 (BCL-6) transcriptional repressor protein is an important regulator of B cell differentiation and is strongly implicated in the development of B cell lymphoma. Expression of the Blimp-1 transcription factor, which is critical for promoting B cell differentiation into plasma cells, is repressed by BCL-6. We have investigated the mechanism for how BCL-6 represses Blimp-1 transcription, and have found that BCL-6 regulates the Blimp-1 promoter through a novel mechanism involving AP-1 elements. Specifically, BCL-6 is a potent repressor of transcriptional activity mediated by AP-1 factors. We found that the zinc-finger region of BCL-6 interacts with c-Jun, JunB, and JunD proteins but does not bind c-Fos or Fra-2 proteins. An estrogen receptor ligand binding domain fusion with the BCL-6 zinc finger domain can act as a estrogen-inducible dominant negative protein and increase AP-1 activity in BCL-6+ cells but not in BCL-6- cells, indicating that endogenous BCL-6 represses AP-1 activity. Additionally, we have confirmed a specific interaction between c-Jun and the zinc finger domain of BCL-6 in vivo using a mammalian two-hybrid assay. Repression of AP-1 function by BCL-6 may be a key mechanism for how BCL-6 regulates gene expression to control inflammation, lymphocyte differentiation, and lymphomagenesis.

Original languageEnglish (US)
Pages (from-to)1922-1929
Number of pages8
JournalJournal of Immunology
Issue number4
StatePublished - Aug 15 2002


ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

Cite this