The progesterone-responsive gene 14-3-3τ enhances the transcriptional activity of progesterone receptor in uterine cells

Abstract

Members of the 14-3-3 family are intracellular dimeric phosphoserine-binding proteins that can associate with and modulate the activities of many proteins. In our efforts to isolate the genes regulated by progesterone (P4) using suppressive subtractive hybridization, we previously found that14-3-3τis one of the genes upregulated by P4. In this study, we demonstrated by quantitative RT-PCR (qRT-PCR), western blot analyses, and immunohistochemistry that 14-3-3τ mRNA and protein levels were increased in the rat uterus after P4treatment. Furthermore, qRT-PCR indicated that P4increased14-3-3τmRNA levels in human endometrial epithelial cells and endometrial stromal cells (ESCs). Western blot and qRT-PCR analyses revealed thatin vitrodecidualization using cAMP and medroxyprogesterone 17-acetate increased levels of 14-3-3τ mRNA and protein in ESCs. We have shown by qRT-PCR and western blot analyses that P4increased the mRNA and protein levels of 14-3-3τ in Ishikawa cells that stably express P4receptor-B (PR-B). Immunocytochemistry revealed that 14-3-3τ colocalizes with PR and translocates from the cytoplasm to the nucleus in response to P4. Moreover, by luciferase reporter assay, we demonstrated that 14-3-3τ enhances the transcriptional activity of PR-B. Taken together, we propose that14-3-3τis a P4-responsive gene in uterine cells that modulates P4signaling.