title: Up-regulation of the SOX3 gene expression by retinoic acid: characterization of the novel promoter-response element and the retinoid receptors involved.
abstract: Sox3/SOX3 gene is considered to be one of the earliest neural markers in vertebrates and it is implicated in the genetic cascades that direct brain formation. We have previously shown that early phases of differentiation and neural induction of NT2/D1 embryonal carcinoma cells by retinoic acid (RA) involve up-regulation of the SOX3 gene expression. Here, we present identification of a novel positive regulatory promoter element involved in RA-dependent activation of the SOX3 gene expression in NT2/D1 cells. This element represents a direct repeat 3-like motif that directly interacts with retinoid X receptor (RXR) alpha in a sequence-specific manner. It is capable of independently mediating the RA effect in a heterologous promoter context and its disruption caused significant reduction of RA/RXR transactivation of the SOX3 promoter. Furthermore, by using synthetic antagonists of retinoid receptors, we have shown for the first time, that RA-induced SOX3 gene expression could be significantly down-regulated by the synthetic antagonist of RXR. Also, this data showed that RXRs, but not RA receptors, are mediators of RA effect on the SOX3 gene up-regulation in NT2/D1 cells. Presented data will be valuable for future investigation of SOX3 gene expression, not only in NT2/D1 model system, but also in diverse developmental, physiological and pathological settings.
authors.affiliation: Institute of Molecular Genetics and Genetic Engineering, Belgrade, Serbia.
authors.forename: Gordana
authors.initials: G
authors.lastname: Nikcević
authors.forename: Tijana
authors.initials: T
authors.lastname: Savić
authors.forename: Natasa
authors.initials: N
authors.lastname: Kovacević-Grujicić
authors.forename: Milena
authors.initials: M
authors.lastname: Stevanović
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D020218:Response Elements / Q000235:genetics*; D047490:Retinoid X Receptor alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012176:Retinoids / Q000494:pharmacology; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; C533894:LG 100815; C533893:LG 101208; D009687:Nuclear Proteins; D047490:Retinoid X Receptor alpha; D012176:Retinoids; C527785:SOX3 protein, human; D055748:SOXB1 Transcription Factors; D014212:Tretinoin