Abstract
The collagenous repeat-containing sequence of 26-kDa protein (CORS-26) was recently described as a new gene that is induced during adipocyte differentiation. Since the transcription factors specificity protein-1 (SP-1) and PPARgamma have been demonstrated to modulate transcriptional activation of adipocytic genes, we investigated the putative role of SPA and PPARgamma in the regulation of the ...
Abstract
The collagenous repeat-containing sequence of 26-kDa protein (CORS-26) was recently described as a new gene that is induced during adipocyte differentiation. Since the transcription factors specificity protein-1 (SP-1) and PPARgamma have been demonstrated to modulate transcriptional activation of adipocytic genes, we investigated the putative role of SPA and PPARgamma in the regulation of the murine CORS-26 promoter. Computer-based sequence analysis revealed two putative SP-1 binding sites and binding sites for PPARgamma and Pit-1 within the TATA-box containing promoter. Electrophoretic mobility shift assays (EMSA) with nuclear extracts from 3T3-L1 adipocytes and appropriate promoter fragments demonstrated that SP-1 binds specifically to both SP-1 binding sites. Specificity was demonstrated by (i) the appearance of supershift bands, (ii) competition experiments and, (iii) by using oligonucleotides carrying mutated SP-1 binding sites. Functional promoter activity was analyzed by Luciferase reporter gene assays and SP-1 was shown to exert inhibitory effects on the transcriptional activation of the murine CORS-26 gene. Additionally, specific binding activity of PPARgamma and Pit-1 to the CORS-26 promoter was demonstrated. Taken together, the present data demonstrate the functionality of the proximal murine CORS-26 promoter, which is regulated specifically by two SPA binding sites via SP-3-independent repressive effects of SP-1 on transcriptional activation. Pit-1 and PPARgamma can bind specifically to the promoter and might play an additive functional role in gene regulation of murine CORS-26. (C) 2004 Elsevier B.V. All rights reserved.
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