title: Ets-1 regulates plasma cell differentiation by interfering with the activity of the transcription factor Blimp-1.
abstract: Development of immunoglobulin-secreting plasma cells from B cells is a tightly regulated process controlled by the action of a number of transcription factors. In particular, the transcription factor Blimp-1 is a key positive regulator of plasmacytic differentiation via its ability to suppress expression of genes involved in the mature B cell program. The transcription factor Ets-1 is a negative regulator of plasmacytic differentiation, as indicated by the development of increased numbers of IgM-secreting plasma cells in Ets-1 knock-out mice. We have previously shown that Ets-1-deficient B cells undergo enhanced differentiation into IgM-secreting plasma cells in response to Toll-like receptor 9 (TLR9) signaling. We now explore the mechanism by which Ets-1 limits differentiation downstream of TLR9. Our results indicate that Ets-1 physically interacts with Blimp-1, which leads to a block in Blimp-1 DNA binding activity and a reduction in the ability of Blimp-1 to repress target genes without interfering with Blimp-1 protein levels. In addition, we show that Ets-1 induces the expression of several target genes that are repressed by Blimp-1, including Pax-5. These results reveal a previously unknown mechanism for the control of Blimp-1 activity by Ets-1 and suggest that expression of Ets-1 must be down-regulated before plasmacytic differentiation can occur.
authors.affiliation: Department of Biochemistry, State University of New York, Buffalo, New York 14214, USA.
authors.forename: Shinu A
authors.initials: SA
authors.lastname: John
authors.forename: James L
authors.initials: JL
authors.lastname: Clements
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Russell
authors.forename: Lee Ann
authors.initials: LA
authors.lastname: Garrett-Sinha
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D019556:COS Cells; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D000882:Haplorhini; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D010954:Plasmacytoma; D000074462:Positive Regulatory Domain I-Binding Factor 1; D050784:Proto-Oncogene Protein c-ets-1 / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D013154:Spleen / Q000276:immunology; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C494041:ETS1 protein, human; D050784:Proto-Oncogene Protein c-ets-1; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C087042:PRDM1 protein, human; D000074462:Positive Regulatory Domain I-Binding Factor 1