Transcriptional activity of estrogen receptors ERα and ERβ in the EtC.1 cerebellar granule cell line

Estrogen receptors alpha and beta (ER alpha and ER beta) are expressed in the cerebellum throughout development and in the adult suggesting an important role of 17-beta-estradiol (E2) in this brain structure. In the present study, we have characterized the functionality of estrogen receptors (ERs) expressed in the immature cerebellar granule cell line (EC)-C-t.1 by transfecting such cells with a luciferase reporter gene (ERE-Luc) coupled to an estrogen response element promoter. The induction of luciferase activity in (EC)-C-t.1 cells by E2 and ER-subtype selective agonists was compared in normal cells and in cells overexpressing human ER alpha or ER beta (hER alpha or hER beta). E2-mediated transcription of the reporter gene was blocked by the ER antagonist ICI 182,780 (ICI), demonstrating the presence of functional native ERs. The selective agonist for ER alpha (PPT) showed a reduced response in luciferase induction compared to E2. Moreover, the ER beta agonist (DPN) was unable to induce luciferase activity. E2-induced ERE-Luc transcription was not increased by overexpression of hERa. In contrast, hER beta overexpression reduced the efficacy of E2 and abolished ER alpha-selective agonist activity. The ER beta-specific agonist did not induce gene reporter activity unless hER beta was overexpressed in the cells, suggesting that the endogenous ER beta in (EC)-C-t.1 cells is transcriptionally inactive. ICI inhibition of E2 responses was not affected by overexpression of the human ERs. The data suggest that ER alpha plays a predominant role in E2-mediated transcription in (EC)-C-t.1 cells. Our data are discussed in view of other reports alluding to the complexity and cell-type specificity of E2-mediated transcription. (c) 2007 Elsevier B.V. All rights reserved.