Agonist-Dependent Downregulation of Progesterone Receptors in Human Cervical Stromal Fibroblasts
Progesterone (P4) maintains uterine quiescence during the majority of pregnancy, whereas diminished progesterone receptor (PR) expression and/or activity (ie, functional P4 withdrawal) promotes parturition. To investigate the regulation of PR expression in cervical stroma, fibroblasts from premenopausal hysterectomy specimens were prepared. Greater than 99% of the cultures were vimentin positive (mesenchymal cell marker) with only occasional cytokeratin-8 positivity (epithelial cell marker) and no evidence of CD31-positive (endothelial cell marker) cells. Cells were immunolabeled with antibodies directed against PRs (PR-A and PR-B), estrogen receptor α (ER-α), and glucocorticoid receptor-α/β (GR-α/β). All cells were uniformly immunopositive for ER-α and GR-α/β but did not express PRs. Incubation of cells with 10–8 mol/L 17β-estradiol induced a time-dependent increase in PR-A and PR-B messenger RNAs (mRNAs) by quantitative real-time polymerase chain reactions and proteins by immunoblotting and immunofluorescence. Incubation of cervical fibroblasts with PR ligands (medroxyprogesterone acetate or Org-2058) downregulated PR-A and PR-B levels. Coincubation of cells with PR ligands plus RU-486, a PR antagonist, partially abrogated agonist-induced receptor downregulation. Dexamethasone, a pure glucocorticoid, had no inhibitory effect on PR expression. These results indicate that progestins and estrogens regulate PR expres...
Source: Reproductive Sciences - Category: Reproduction Medicine Authors: Ackerman, W. E., Summerfield, T. L., Mesiano, S., Schatz, F., Lockwood, C. J., Kniss, D. A. Tags: Original Articles Source Type: research
More News: Dexamethasone | Estradiol | Hormones | Hysterectomy | Medroxyprogesterone | Pregnancy | Reproduction Medicine