| Summary: | 碩士 === 國立臺灣大學 === 生化科學研究所 === 88 === Pregnancy-specific glycoproteins (PSGs) are specifically expressed in placenta and the level of PSG increases exponentially during placental development. To understand the regulation of PSG expression, we characterized the promoter elements of a rodent PSG gene, rnCGM3. The promoter region of rnCGM3 gene contains three regulatory elements ( FPI, FPII, and FPIII ). The FPII-binding factor is shown to be C/EBPbeta, which enhances rnCGM3 gene expression. In previous study, we isolated a FPIII-binding factor, rRBPJk-2N (rodent Jk recombination signal sequence binding protein). In this study, we further revealed that RBPJk can bind to FPIII site by electrophoretic mobility shift assay. In a transient expression assay, we also demonstrated that rRBPJk-2N repressed the expression from an FPIII-driven SV40 promoter, but the active intracellular domain of Notch (NotchIC) could counteract the repressor activities of rRBPJk-2N. In the native context of rnCGM3 promoter, the promoter activity stimulated by C/EBPbeta was also repressed by rRBPJk-2N, but enhanced by NotchIC. In addition, we found that NotchIC stimulated C/EBPbeta-dependent expression was through another RBPJk site within the FPI site. Our data suggest that the placenta-specific expression of rnCGM3 may be connected to the C/EBPbeta and Notch signaling pathway.
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