Interplay between proximal and distal promoter elements is required for squamous differentiation marker induction in the bronchial epithelium: role for ESE-1, Sp1, and AP-1 proteins.
Overexpression of SPRR1B in bronchial epithelial cells is a marker for early metaplastic changes induced by various toxicants/carcinogens. Previously, we have shown that the transcriptional stimulation of SPRR1B expression by phorbol 12-myristate 13-acetate (PMA) is mainly mediated by a -150/-94 bp enhancer harboring two critical 12-O-tetradecanoylphorbol-13-acetate-responsive elements (TREs) and by Jun.Fra-1 dimers. Here, we show that a region between -54 and -39 bp containing an ETS-binding site (EBS) and a GC box is essential for both basal and PMA-inducible SPRR1B transcription. In vivo footprinting demonstrated binding of transcription factors to these elements. However, unlike enhancer TREs, exposure of cells to PMA did not significantly alter the footprinting pattern at these elements. Mutations that crippled both the EBS and GC box suppressed both basal and PMA-inducible SPRR1B transcription. Consistent with this, overexpression of EBS-binding proteins ESE-1 and ESE-3 significantly stimulated SPRR1B promoter activity. Furthermore, preceding SPRR1B transcription, PMA up-regulated mRNA expression of ETS family members such as ESE-1 and ESE-3. Although ESE-1 synergistically activated c-Jun- and PMA-enhanced SPRR1B transcription, coexpression of Sp1 and ESE-1 showed no synergistic or additive effect on promoter activity, indicating an obligatory role for AP-1 proteins in such regulation. In support of this notion, deletion or mutation of two functional TREs inhibited ESE-1- and Sp1-enhanced promoter activation. Thus, the interaction between ESE-1 and Sp1, and AP-1 proteins that bind to the proximal and distal promoter regions, respectively, play a critical role in the induction of squamous differentiation marker expression in bronchial epithelial cells.
Reddy
Sekhar P M
SP
Department of Environmental Health Sciences, Division of Physiology, The Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205, USA. sreddy@jhsph.edu
Vuong
Hue
H
Adiseshaiah
Pavan
P
D001483:Base Sequence; D001665:Binding Sites; D014408:Biomarkers, Tumor; D001984:Bronchial Neoplasms / Q000235:genetics* / Q000378:metabolism; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism; D055233:Cornified Envelope Proline-Rich Proteins; D004268:DNA-Binding Proteins; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D004848:Epithelium / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009841:Oligonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics* / Q000502:physiology*; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate; D013997:Time Factors; D015534:Trans-Activators / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000502:physiology*; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D014408:Biomarkers, Tumor; D002273:Carcinogens; D055233:Cornified Envelope Proline-Rich Proteins; D004268:DNA-Binding Proteins; C105529:ELF3 protein, human; D008565:Membrane Proteins; D009841:Oligonucleotides; D011506:Proteins; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D014157:Transcription Factors; C524533:SPRR1B protein, human; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate