Differential interaction of nuclear factors with the leukocyte-specific pp52 promoter in B and T cells.
The leukocyte-specific, cytoskeleton-binding pp52 (LSP-1, WP-34) protein is widely expressed in multiple leukocyte lineages, including B and T lymphocytes, granulocytes, and macrophages. We previously detected a tissue-specific promoter preceding the exon encoding the N terminus of the pp52 leukocyte protein. Here we describe the functional characterization of this promoter and identification of the factors in B and T cells that regulate its activity. The pp52 promoter contains an initiator specifying the unique 5' terminus of pp52 mRNA, tandem pairs of Ets and SP1 motifs, and a lone C/EBP motif. All these motifs are essential and collectively control transcriptional activity. DNA binding studies and Ab supershift assays revealed that different combinations of factors interact with these motifs in B cells vs T cells. The Ets motifs are preferentially bound by PU-1 in B cell extracts from all stages of development, whereas a different Ets family member reacts with these motifs in T cell extracts. The C/EBP motif is bound by Ig/EBP-1 in pre-B cell and T cell extracts, but is replaced by nuclear factor-IL-6beta or a nuclear factor-IL-6beta-Ig/EBP-1 heterodimer in plasmacytoma cell extracts. Despite its reported role as a negative regulator of transcription, Ig/EBP-1 appears to exert a stimulatory effect on this promoter. These findings reveal the features controlling the pp52 promoter in B and T cells and provide the foundation for determining the regulation of this promoter in other leukocyte lineages.
Omori
S A
SA
Molecular Biology Institute and Department of Microbiology and Immunology, University of California School of Medicine, Los Angeles 90095, USA.
Smale
S
S
O'Shea-Greenfield
A
A
Wall
R
R
D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism*; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D015513:Oncogene Proteins; D011401:Promoter Regions, Genetic; D050783:Proto-Oncogene Proteins c-ets; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D022762:CCAAT-Enhancer-Binding Proteins; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; C086924:Elk3 protein, mouse; C489183:LSP1 protein, human; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D016329:Sp1 Transcription Factor; D014157:Transcription Factors