Analysis of gene expression and Ig transcription in PU.1/Spi-B-deficient progenitor B cell lines.
A number of presumptive target genes for the Ets-family transcription factor PU.1 have been identified in the B cell lineage. However, the precise function of PU.1 in B cells has not been studied because targeted null mutation of the PU.1 gene results in a block to lymphomyeloid development at an early developmental stage. In this study, we take advantage of recently developed PU.1(-/-)Spi-B(-/-) IL-7 and stromal cell-dependent progenitor B (pro-B) cell lines to analyze the function of PU.1 and Spi-B in B cell development. We show that contrary to previously published expectations, PU.1 and/or Spi-B are not required for Ig H chain (IgH) gene transcription in pro-B cells. In fact, PU.1(-/-)Spi-B(-/-) pro-B cells have increased levels of IgH transcription compared with wild-type pro-B cells. In addition, high levels of Igkappa transcription are induced after IL-7 withdrawal of wild-type or PU.1(-/-)Spi-B(-/-) pro-B cells. In contrast, we found that Iglambda transcription is reduced in PU.1(-/-)Spi-B(-/-) pro-B cells relative to wild-type pro-B cells after IL-7 withdrawal. These results suggest that Iglambda, but not IgH or Igkappa, transcription, is dependent on PU.1 and/or Spi-B. The PU.1(-/-)Spi-B(-/-) pro-B cells have other phenotypic changes relative to wild-type pro-B cells including increased proliferation, increased CD25 expression, decreased c-Kit expression, and decreased RAG-1 expression. Taken together, our observations suggest that reduction of PU.1 and/or Spi-B activity in pro-B cells promotes their differentiation to a stage intermediate between late pro-B cells and large pre-B cells.
Schweitzer
Brock L
BL
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Medical Sciences Building 3006, 231 Albert Sabin Way, Cincinnati, OH 45267, USA.
DeKoter
Rodney P
RP
D000818:Animals; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D017077:Culture Media, Conditioned / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D020869:Gene Expression Profiling / Q000379:methods; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D005803:Genes, Immunoglobulin; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism*; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis / Q000235:genetics; D007145:Immunoglobulin kappa-Chains / Q000235:genetics / Q000378:metabolism; D007146:Immunoglobulin lambda-Chains / Q000235:genetics / Q000378:metabolism; D016130:Immunophenotyping; D015851:Interleukin-7 / Q000378:metabolism; D018655:Lymphocyte Count; D051379:Mice; D018345:Mice, Knockout; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D017384:Sequence Deletion; D015534:Trans-Activators / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D014157:Transcription Factors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D014158:Transcription, Genetic / Q000276:immunology*; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology; D000099232:Proto-Oncogene Protein Spi-1
D017077:Culture Media, Conditioned; D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D015851:Interleukin-7; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000099232:Proto-Oncogene Protein Spi-1; C076877:SPIB protein, human