title: Blimp-1-dependent repression of Pax-5 is required for differentiation of B cells to immunoglobulin M-secreting plasma cells.
abstract: B-cell lineage-specific activator protein (BSAP), encoded by the Pax-5 gene, is critical for B-cell lineage commitment and B-cell development but is not expressed in terminally differentiated B cells. We demonstrate a direct connection between BSAP and B-lymphocyte-induced maturation protein 1 (Blimp-1), a transcriptional repressor that is sufficient to drive plasmacytic differentiation. Blimp-1 binds a site on the Pax-5 promoter in vitro and in vivo and represses the Pax-5 promoter in a binding-site-dependent manner. By ectopically expressing Blimp-1 or a competitive inhibitor of Blimp-1, we show that Blimp-1 is both necessary and sufficient to repress Pax-5 during plasmacytic differentiation of primary splenic B cells. Blimp-1-dependent repression of Pax-5 is sufficient to regulate BSAP targets CD19 and J chain and is necessary but not sufficient to induce XBP-1. We further show that repression of Pax-5 is required for Blimp-1 to drive differentiation of splenocytes to immunoglobulin M-secreting cells. Thus, repression of Pax-5 plays a critical role in the Blimp-1-dependent program of plasmacytic differentiation.
authors.affiliation: Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
authors.forename: Kuo-I
authors.initials: KI
authors.lastname: Lin
authors.forename: Cristina
authors.initials: C
authors.lastname: Angelin-Duclos
authors.forename: Tracy C
authors.initials: TC
authors.lastname: Kuo
authors.forename: Kathryn
authors.initials: K
authors.lastname: Calame
mesh_terms: D000818:Animals; D018941:Antigens, CD19 / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D001665:Binding Sites; D002454:Cell Differentiation; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D007144:Immunoglobulin J-Chains / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism*; D051379:Mice; D051757:PAX5 Transcription Factor; D000074462:Positive Regulatory Domain I-Binding Factor 1; D011401:Promoter Regions, Genetic; D000071701:Regulatory Factor X Transcription Factors; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D000071717:X-Box Binding Protein 1
chemical_list: D018941:Antigens, CD19; D004268:DNA-Binding Proteins; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M; D051757:PAX5 Transcription Factor; C497282:Pax5 protein, mouse; C513258:Prdm1 protein, mouse; D000071701:Regulatory Factor X Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D000074462:Positive Regulatory Domain I-Binding Factor 1