Active intracellular domain of Notch enhances transcriptional activation of CCAAT/enhancer binding protein beta on a rat pregnancy-specific glycoprotein gene.
Pregnancy-specific glycoproteins (PSGs) are primarily expressed in the placenta and become the major glycoproteins at term. To understand the regulation of PSG expression, we characterized the promoter elements of a rodent PSG gene, rnCGM3, and delineated three nuclear protein binding sites: FPI, -II, and -III in the 5'-flanking region of the gene. The FPII-binding factor is shown to be C/EBPbeta, which positively regulates rnCGM3 expression [Chen, H., et al. (1995) DNA Cell Biol. 14, 681-688]. In the current study, we used the yeast one-hybrid system to isolate transcription factors binding to the FPIII site and demonstrated that a rodent J kappa recombination signal sequence binding protein, rRBPJ kappa-2N, bound to the FPIII site. Electrophoretic mobility shift assay with rat placental nuclear proteins revealed a constitutive occupancy of the FPIII site by RBPJ kappa. By transient expression analyses, we demonstrated that rRBPJ kappa-2N repressed the expression from an FPIII-driven SV40 promoter. However, this repression effect was counteracted by the active intracellular domain of Notch (NotchIC). Using the native rnCGM3 promoter construct, we demonstrated that the promoter activity stimulated by C/EBP beta was also repressed by rRBPJ kappa-2N but enhanced by NotchIC. Additionally, we found that NotchIC can stimulate expression through another RBPJkappa site within the FPI site. A functional interaction between factors binding to the FPI, FPII, and FPIII sites is proposed.
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Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan, and Graduate Institute of Biochemical Sciences, National Taiwan University, Taipei 10098, Taiwan. hwchen@gate.sinica.edu.tw
Chong
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Liu
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D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins; D019556:COS Cells; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D004742:Enhancer Elements, Genetic; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000138:chemical synthesis / Q000502:physiology; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D007424:Intracellular Fluid / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics / Q000502:physiology*; D011268:Pregnancy-Specific beta 1-Glycoproteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D051880:Receptors, Notch; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008565:Membrane Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D011268:Pregnancy-Specific beta 1-Glycoproteins; C497570:RBPJ protein, human; C497572:Rbpjl2 protein, rat; D051880:Receptors, Notch; D015534:Trans-Activators