Progesterone and Estrogen Receptors in GH3 Cells

Abstract

GH3 cells are shown to contain cytosolic progesterone receptor in a mean concentration of 270 fmol/mg protein with a dissociation constant (K_D) for promegestone of 3 × 10^-9M (4°C). Estrogen receptor (K_D = 1.8 × 10^-10M) is demonstrated in cytosol (121 fmol/mg protein) as well as in 0.4 M KCl extracts (89 fmol/mg protein) of crude nuclear fractions. No progesterone receptor was detectable in the nuclear fraction. Both receptors are characterized by isoelectric focussing and by competition experiments. Addition of 10^-8M estradiol to the growth medium increases progesterone receptor levels up to five, suggesting that the progesterone receptor is under estrogenic control.

Activation of the silent progesterone receptor gene by ectopic expression of estrogen receptors in a rat fibroblast cell line

“…To test whether the PR induction by E2 in Ratl+ER.l cells occurs at the mRNA level, we performed the RT-PCR assay using rat PR primers (Figure 9A; Park & Mayo, 1991). Total RNA from GH3 cells,which express PR (data not shown; Roos et al, 1980), exhibited an amplified DNA fragment of 325 bp, consistent with observationsofthe rat uterus (Park & Mayo, 1991). Furthermore, RT-PCR assay of total RNA using PR and RPL19 primers.…”

Effects of estradiol and progesterone on prolactin transcriptional activity in somatolactotrophic cells

“…E2 has also been shown to decrease the number of dopamine receptors in the anterior pituitary [20,21]. Cloned prolactin-producing GH3 cells also have E2 and P4 receptors [22], and GH3 cell function was shown to be modulated by these steroids. Haug et al demonstrated that E2 stimulates prolactin release, whereas P4 decreases prolactin production as well as inhibiting the stimulatory effect of E2 on GH3 cells [23].…”