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Title: Transfection with steroid-responsive reporter constructs shows glucocorticoid rather than androgen responsiveness in cultured Sertoli cells
Authors: Denolet, Evi ×
De Gendt, Karel
Swinnen, Johan
Verrijdt, Guy
Deboel, Ludo
Roskams, Tania
Verhoeven, Guido #
Issue Date: Jan-2006
Publisher: Pergamon Press
Series Title: Journal of Steroid Biochemistry and Molecular Biology vol:98 issue:2-3 pages:164-173
Abstract: It remains unclear why it has proven so difficult to identify androgen target genes in cultured Sertoli cells. Given the lack of useful endogenous reporter genes, we studied the androgen and glucocorticoid responsiveness of these cells by transfection with three different steroid-responsive reporter constructs. The constructs were driven by the tyrosine aminotransferase steroid-responsive region (TAT-GRE4x-Luc), the mouse mammary tumor virus promoter (MMTV-Luc) and the Pem homeobox gene proximal promoter respectively (Pem-Luc). These constructs can be activated either by both the glucocorticoid receptor (GR) and the androgen receptor (AR) (TAT-GRE4x-Luc and MMTV-Luc) or selectively by the AR (Pem-Luc). Despite high transfection efficiency (30-40%) none of the constructs could be activated by treatment of the Sertoli cells with testosterone, 5alpha-dihydrotestosterone or synthetic androgens. Even pretreatment with follicle-stimulating hormone to raise AR levels (from 31 up to 82fmol/mg protein) did not result in androgen responsiveness. In contrast, treatment with dexamethasone markedly stimulated TAT-GRE4x-Luc and MMTV-Luc activity. GR levels reached a value of 172fmol/mg protein in the cultured cells and both AR and GR displayed homogeneous distribution by immunocytochemical evaluation. Androgen responsiveness was restored and glucocorticoid responsiveness was increased by cotransfection with AR or GR expression constructs. Under cotransfection conditions, 1nM of testosterone (a concentration that is some 100 times lower than that estimated to be present in the testis) was sufficient to stimulate the TAT-GRE4x-Luc maximally. Our data indicate that cultured Sertoli cells respond better to glucocorticoids than to androgens and that one of the factors limiting androgen responsiveness is the availability of AR. Other factors limiting the transactivation capacity of the (endogenous) AR, however, cannot be excluded.
ISSN: 0960-0760
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Clinical and Experimental Endocrinology
Biochemistry Section (Medicine) (-)
Translational Cell & Tissue Research
Laboratory of Lipid Metabolism and Cancer (+)
× corresponding author
# (joint) last author

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