Proszkowiec-Weglarz M, Porter TE. Functional characterization of chicken glucocorticoid and mineralocorticoid receptors. Am J

gand-activated transcription factors that belong to the nuclear hor-mone receptor superfamily. Little is known about the function of GR and MR in avian species. Recently, the chicken homologue of the GR (cGR) gene was cloned, and its tissue-specific expression was char-acterized, whereas the full-length sequence of the chicken MR (cMR) gene remains unknown. Therefore, the aims of this project were to clone the full-length cMR and to functionally characterize both chicken receptors. Cos-7 cells were transiently transfected with cGR or cMR expression vectors along with a glucocorticoid response element-luciferase (GRE-Luc) reporter construct. Transfected cells were then treated with increasing doses of corticosterone (CORT) or aldosterone (ALDO) alone and with GR or MR antagonists (ZK98299 and spironolactone, respectively). Transactivation of cGR or cMR was evaluated by luciferase assay. CORT and ALDO induced cGR-and cMR-driven transcriptional activity in a dose-dependent manner