• Molecules and Cells
• /
• 제27권3호
• /
• pp.351-357
• /
• 2009

Phytoestrogens are the natural compounds isolated from plants, which are structurally similar to animal estrogen, $17{\beta}$-estradiol. Tectoridin, a major isoflavone isolated from the rhizome of Belamcanda chinensis. Tectoridin is known as a phytoestrogen, however, the molecular mechanisms underlying its estrogenic effect are remained unclear. In this study we investigated the estrogenic signaling triggered by tectoridin as compared to a famous phytoestrogen, genistein in MCF-7 human breast cancer cells. Tectoridin scarcely binds to ER ${\alpha}$ as compared to $17{\beta}$-estradiol and genistein. Despite poor binding to ER ${\alpha}$, tectoridin induced potent estrogenic effects, namely recovery of the population of cells in the S-phase after serum starvation, transactivation of the estrogen response element, and induction of MCF-7 cell proliferation. The tectoridin-induced estrogenic effect was severely abrogated by treatment with U0126, a specific MEK1/2 inhibitor. Tectoridin promoted phosphorylation of ERK1/2, but did not affect phosphorylation of ER ${\alpha}$ at $Ser^{118}$. It also increased cellular accumulation of cAMP, a hallmark of GPR30-mediated estrogen signaling. These data imply that tectoridin exerts its estrogenic effect mainly via the GPR30 and ERK-mediated rapid nongenomic estrogen signaling pathway. This property of tectoridin sets it aside from genistein where it exerts the estrogenic effects via both an ER-dependent genomic pathway and a GPR30-dependent nongenomic pathway.

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 2003년도 한국생물과학협회 학술발표대회
• /
• pp.175.2-175
• /
• 2003

No Abstract, See Full Text

• 대한의생명과학회지
• /
• 제23권1호
• /
• pp.17-24
• /
• 2017

Estrogens are effective neuroprotectants in vivo and in vitro. To obtain a better insight into the molecular mechanisms of action of neuroprotection by $17{\beta}-estradiol$ (E2), we examined the differential effects of E2 on the fluidity of synaptosomal plasma membrane vesicles (SPMV) isolated from rat cerebral cortex. Intramolecular excimerization of 1,3-di(1-pyrenyl)-propane (Py-3-Py) was used to investigate the effects of E2 on the bulk and annular lateral diffusion of the SPMV. In addition, we examined the effects of E2 on the rotational diffusion of individual leaflet of SPMV exploiting selective quenching of outer monolayer 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence by trinitrophenyl groups. The $F{\ddot{o}}rster$ distance $R_0$ value for the tryptophan-Py-3-Py donor-acceptor pair was $26.9{\AA}$. E2 increased the lateral mobility of both bulk and annular lipids in SPMV in a dose-dependent manner, but a larger effect on bulk lipids was observed. Although E2 decreased the anisotropy of DPH in SPMV, E2 had a greater fluidizing effect on the outer leaflet compared to the inner leaflet. These results suggest that E2 selectively fluidizes the more fluid regions within SPMV. It is highly probable that E2 mostly fluidizes the bulk lipids, away from either annular lipids or lipid rafts, in the outer leaflet of SPMV. This selective fluidization may be one of the nongenomic mechanisms of neuroprotection by E2.

• Animal cells and systems
• /
• 제5권1호
• /
• pp.51-57
• /
• 2001

We have previously shown that oocyte maturation is induced by an immobilized progesterone, progesterone-3-carboxymethyloxime - bovine serum albumin conjugate (P-BSA) in Rana dybowskii. In this study, we confirmed the maturation inducing activity of P-BSA on Xenopus oocyte and examined the binding character of the immobilized progesterone on the surface of Xenopus oocytes after removal of the vitelline layer. P-BSA induced maturation of Xenopus oocytes but E-BSA failed to do so as observed in Rana. Binding of the immobilized progesterone, fluorescein isothiocyanate-labeled progesterone-3-0-carboxymethyloxime-BSA (P-BSA-FITC) on the devitellined oocytes surface was examined by fluorescence confocal microscopy. The binding affinity of P-BSA-FITC to the devitellined oocyte was higher than that of estrogen-BSA-FITC (E-BSA-FITC) or testosterone-BSA-FITC (T-BSA-FITC). The binding disappeared in the presence of excess free progesterone but not in the presence of free estrogen. Maximum binding occurred after two-hours of incubation with P-BSA-FITC at pH 7.5. Stronger binding occurred in oocytes at stage Vl than stage IV, and in vitro treatment of hCG enhanced the binding. Taken together, these results suggest that a specific receptor for progesterone exists on the plasma membrane of Xenopus oocytes and that progesterone acts initially on this putative receptors and triggers generation of membrane-mediated second messengers during the early stage of oocyte maturation In amphibians.

• Journal of Ginseng Research
• /
• 제43권4호
• /
• pp.527-538
• /
• 2019

Background: Ginsenoside Rg1 was shown to exert ligand-independent activation of estrogen receptor (ER) via mitogen-activated protein kinase-mediated pathway. Our study aimed to delineate the mechanisms by which Rg1 activates the rapid ER signaling pathways. Methods: ER-positive human breast cancer MCF-7 cells and ER-negative human embryonic kidney HEK293 cells were treated with Rg1 ($10^{-12}M$, $10^{-8}M$), $17{\beta}$-estradiol ($10^{-8}M$), or vehicle. Immunoprecipitation was conducted to investigate the interactions between signaling protein and ER in MCF-7 cells. To determine the roles of these signaling proteins in the actions of Rg1, small interfering RNA or their inhibitors were applied. Results: Rg1 rapidly induced $ER{\alpha}$ translocation to plasma membrane via caveolin-1 and the formation of signaling complex involving linker protein (Shc), insulin-like growth factor-I receptor, modulator of nongenomic activity of ER (MNAR), $ER{\alpha}$, and cellular nonreceptor tyrosine kinase (c-Src) in MCF-7 cells. The induction of extracellular signal-regulated protein kinase and mitogen-activated protein kinase kinase (MEK) phosphorylation in MCF-7 cells by Rg1 was suppressed by cotreatment with small interfering RNA against these signaling proteins. The stimulatory effects of Rg1 on MEK phosphorylation in these cells were suppressed by both PP2 (Src kinase inhibitor) and AG1478 [epidermal growth factor receptor (EGFR) inhibitor]. In addition, Rg1-induced estrogenic activities, EGFR and MEK phosphorylation in MCF-7 cells were abolished by cotreatment with G15 (G protein-coupled estrogen receptor-1 antagonist). The increase in intracellular cyclic AMP accumulation, but not Ca mobilization, in MCF-7 cells by Rg1 could be abolished by G15. Conclusion: Ginsenoside Rg1 exerted estrogenic actions by rapidly inducing the formation of ER containing signalosome in MCF-7 cells. Additionally, Rg1 could activate EGFR and c-Src ER-independently and exert estrogenic effects via rapid activation of membrane-associated ER and G protein-coupled estrogen receptor.