Understanding the regulation of pituitary progesterone receptor expression and phosphorylation.
Reproduction
; 149(6): 615-23, 2015 Jun.
Article
em En
| MEDLINE
| ID: mdl-25926689
ABSTRACT
Administration of human FSH (hFSH) during the diestrus phase in cyclic rats is followed by a reduction in the preovulatory LH surge. This inhibitory action of FSH involves a decrease in the stimulatory effect of gonadotrope progesterone receptor (PR) activation, in a ligand-dependent (progesterone) and -independent (GNRH) manner. PR activation and action are mandatory for LH surge, and are dependent on the phosphorylation of serine (Ser) residues. Together with this post-translational modification, PR is marked for downregulation by proteasome machinery. These experiments used the western blotting technique to measure pituitary expression of PR-A and PR-B isoforms and phosphorylation levels of Ser294 and Ser400 PR-B in rats bearing i) hFSH treatment or ii) PR downregulation. Treatment with hFSH reduced LH secretion and increased that of estradiol in proestrus afternoon. hFSH injections, without altering PR-A and PR-B content or ratio, caused a reduction in phosphorylation of Ser294 and Ser400 but only when pituitaries were previously challenged with progesterone or GNRH for 2âh. However, while pSer294 levels increased after 2âh of pituitary incubation with progesterone or GNRH, those of pSer400 were not modified by these in vitro treatments. Finally, progesterone had a biphasic effect in 2-h incubations increased pituitary PR-A and PR-B content, but after 8âh caused downregulation and altered PR-APR-B ratio. The results provide a potential mechanism through which LH levels are decreased by hFSH administration and better understanding of the control of PR expression and phosphorylation in rat pituitaries.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Hipófise
/
Receptores de Progesterona
/
Processamento de Proteína Pós-Traducional
/
Regulação da Expressão Gênica
Limite:
Animals
Idioma:
En
Revista:
Reproduction
Assunto da revista:
MEDICINA REPRODUTIVA
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Espanha