G Protein-coupled Estrogen Receptor Antagonist G15 Research Articles

Genistein Alleviates Dextran Sulfate Sodium-induced Ulcerative Colitis in Mice by Regulating Th17/Treg Cell Balance: Implication for the G Protein-coupled Estrogen Receptor

Objectives This study aimed to evaluate the therapeutic effects and mechanism of genistein on dextran sulfate sodium-induced mouse model of ulcerative colitis (UC). Materials and Methods A DSS-induced mouse model for UC was used in this study. Mice were then treated with genistein or a combination of genistein and the G protein-coupled estrogen receptor (GPER) antagonist G15. Colon length, disease activity index (DAI), spleen index (SI), histopathological alterations, and integrity of the colonic barrier were evaluated. The expression of inflammatory cytokines and antioxidant capacity were detected. Populations of T helper 17 cells (Th17) and Regulatory T cells (Treg) in the mesenteric lymph nodes (MLN) were analyzed. The expression of a transcription factor for Th17 and Treg in the colonic tissues was detected. Results Genistein treatment significantly alleviated DSS-induced colitis, summarized as increased colonic length, decreased DAI, SI, improved histopathological alterations, and colonic barrier integrity. Genistein treatment restrained pro-inflammatory cytokines and oxidative enzyme release while promoting anti-inflammatory and anti-oxidative enzyme release. Flow cytometry indicated that genistein significantly reduced the Th17 population while boosting Treg populations. Furthermore, genistein inhibited the expression of transcription factors associated with Th17 and promoted the expression of transcription factors associated with Treg in the colonic tissue. Intriguingly, these observed effects of genistein were abolished when UC mice were treated with a combination of genistein and GPER antagonist G15. Conclusion This study suggests that genistein is potent in protecting against DSS-induced colonic injuries by rebalancing Th17/Treg and that GPER may be a vital target for genistein-mediated immunomodulatory effects in UC.

MiR-206 inhibits estrogen signaling and ovarian cancer cell migration without affecting GPER

AimsEstrogen-regulated pathways are involved in the etiology and progression of epithelial ovarian cancer (EOC), but the relative contribution of estrogen receptor isoforms is unclear. Only a subset of patients responds to antiestrogens including tamoxifen. Based on our previous evidence that miR-206 behaves as an oncosuppressor in EOC, we hypothesized that miR-206 would interfere with G protein-coupled estrogen receptor (GPER)-mediated signaling and cell motility. Main methodsPFKFB3 and FAK proteins from OC cells challenged with selective estrogen receptor agonist and antagonist were measured by Western blotting. Cell proliferation and motility were analyzed by MTT and Boyden chamber, respectively. Estrogen-dependent cells were transfected with miR-206 mimic or control using Lipofectamine. Key findingsThe migration of SKOV3 and OVCAR5 cells significantly increased following treatment with 17β-estradiol (E2) and the selective GPER agonist G1. However, tamoxifen failed to inhibit E2 effect and even promoted SKOV3 cell migration. Estrogen receptor ligands did not affect SKOV3 proliferation. The GPER antagonist G15 significantly prevented E2-mediated upregulation of PFKFB3 expression, while G1 concentration-dependently upregulated PFKFB3 levels. Consistent with the functional link between PFKFB3 and FAK activation, E2 and G1 increased FAK phosphorylation at Tyr397. Transfection with miR-206 abolished estrogen-induced EOC migration and down-regulated PFKFB3 protein levels. Notably, miR-206 transfection reduced ERα protein abundance, whereas GPER amount was unchanged. SignificanceBy blocking estrogen signaling and G1-induced EOC cell invasiveness with no direct interference with GPER levels, miR-206 mimics have the potential to act as pathway-selective antagonists and deserve further testing as RNA therapeutics in estrogen-dependent EOC.

Epimedin B exerts neuroprotective effect against MPTP-induced mouse model of Parkinson's disease: GPER as a potential target

Mitochondrial dysfunction and oxidative stress play important roles in the neuropathogenesis of Parkinson’s disease (PD). Epimedin B, the second highest active ingredient in the flavonoids of Herba Epimedii, has been proven effective in treating osteoporosis and oxaliplatin-induced peripheral neuropathy. The present study aims to investigate the neuroprotective effects of Epimedin B in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP)-induced mouse model of PD, and the involvement of G protein-coupled estrogen receptor (GPER)-mediated anti-apoptosis as well as anti-endoplasmic reticulum stress. Molecular docking revealed that Epimedin B could directly bind to GPER at the same site as GPER agonist G1 and the binding energy was − 7.3 kcal/mol. Epimedin B treatment ameliorated MPTP-induced motor dysfunction and alleviated the decreased contents of DA with its metabolites in the striatum and the loss of tyrosine hydroxylase-immunoreactive (TH-IR) neurons in the substantial nigra pars compacta (SNpc). Epimedin B treatment markedly prevented MPTP-induced changes in apoptosis-related protein Bcl-2 and Bax as well as endoplasmic reticulum stress-related protein glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP). Pharmacological blockade with GPER antagonist G15 could antagonize these neuroprotective effects of Epimedin B on the nigrostriatal system. Moreover, the anti-apoptosis and anti-endoplasmic reticulum stress effects of Epimedin B against MPTP toxicity were significantly reduced in GPER knockout (GPER-/-) mice. The present study provides the first evidence that Epimedin B can protect against MPTP-induced PD mice model. GPER may be a potential target for the neuroprotective effect of Epimedin B against PD.

Genistein accelerates glucose catabolism via activation the GPER-mediated cAMP/PKA-AMPK signaling pathway in broiler chickens

Genistein, the most abundance of phytoestrogens in soybeans, has beneficial effects in regulating metabolism-related disease; however, there is few available literatures about whether genistein regulates glucose metabolism that in turn affects the lipid accumulation in animals or humans. The current study showed that genistein promoted glucose uptake by enhancing glucose transporter-2 (GLUT2) protein level; and it also increased the activity of phosphofructokinase-1 (PFK) and pyruvate dehydrogenase (PDH), and the mRNA level of succinate dehydrogenase (SDH) both in broiler chickens or hepatocytes. Moreover, genistein obviously increased the p-LKB1 and p-AMPKα protein levels both in vivo and in vitro. Furthermore, the enhancement of genistein on glucose uptake and catabolism were reversed in hepatocytes pre-treated with AMPK inhibitor Compound C, and the increasing of genistein on the p-LKB1 and p-AMPKα protein levels were also reversed in hepatocytes pre-treated with PKA inhibitor H89. Importantly, the results showed that genistein simultaneously increased the estrogen receptor β (ERβ) and G protein-coupled estrogen receptor (GPER) protein levels, but the elevation effect of genistein on cAMP content was completely reversed in hepatocytes pre-treated with GPER antagonist G15, rather than ERβ inhibitor PHTPP. Meanwhile, the increasing of p-LKB1 and p-AMPKα protein levels induced by genistein were also reversed in hepatocytes pre-treated with G15. Collectively, our data demonstrated that genistein improves glucose metabolism via activating the GPER-mediated cAMP/PKA-AMPK signaling pathway. These findings provide theoretical basis for genistein as a promising nutritional supplemental to alleviate metabolism disorders and related diseases in animals or even humans.

Activation of G protein coupled estrogen receptor prevents chemotherapy-induced intestinal mucositis by inhibiting the DNA damage in crypt cell in an extracellular signal-regulated kinase 1- and 2- dependent manner

Chemotherapy-induced intestinal mucositis (CIM) is a common adverse reaction to antineoplastic treatment with few appropriate, specific interventions. We aimed to identify the role of the G protein coupled estrogen receptor (GPER) in CIM and its mechanism. Adult male C57BL/6 mice were intraperitoneally injected with 5-fluorouracil to establish the CIM model. The selective GPER agonist G-1 significantly inhibited weight loss and histological damage in CIM mice and restored mucosal barrier dysfunction, including improving the expression of ZO-1, increasing the number of goblet cells, and decreasing mucosal permeability. Moreover, G-1 treatment did not alter the antitumor effect of 5-fluorouracil. In the CIM model, G-1 therapy reduced the expression of proapoptotic protein and cyclin D1 and cyclin B1, reversed the changes in the number of TUNEL+ cells, Ki67+ and bromodeoxyuridine+ cells in crypts. The selective GPER antagonist G15 eliminated all of the above effects caused by G-1 on CIM, and application of G15 alone increased the severity of CIM. GPER was predominantly expressed in ileal crypts, and G-1 inhibited the DNA damage induced by 5-fluorouracil in vivo and vitro, as confirmed by the decrease in the number of γH2AX+ cells in the crypts and the comet assay results. Referring to the data from GEO dataset we verified GPER activation restored ERK1/2 activity in CIM and 5-fluorouracil-treated IEC-6 cells. Once the effects of G-1 on ERK1/2 activity were abolished with the ERK1/2 inhibitor PD0325901, the effects of G-1 on DNA damage both in vivo and in vitro were eliminated. Correspondingly, all of the manifestations of G-1 protection against CIM were inhibited by PD0325901, such as body weight and histological changes, the mucosal barrier, the apoptosis and proliferation of crypt cells. In conclusion, GPER activation prevents CIM by inhibiting crypt cell DNA damage in an ERK1/2-dependent manner, suggesting GPER might be a target preventing CIM.

GPER and IGF-1R mediate the anti-inflammatory effect of genistein against lipopolysaccharide (LPS)-induced nigrostriatal injury in rats

Neuroinflammation plays an important role in the pathogenesis of Parkinson's disease (PD). Genistein is an estrogen-like phytoestrogen that can exert biological effects via the crosstalk of estrogen receptor and insulin-like growth factor 1 receptor (IGF-1R). The present study aimed to evaluate the involvement of G protein-coupled estrogen receptor (GPER) and IGF-1R in the anti-inflammatory effects of genistein against lipopolysaccharide (LPS)-induced nigrostriatal injury in ovariectomized rats. Our results showed that genistein treatment could ameliorate the apomorphine-induced rotational behavior in LPS-induced inflammatory PD rat model. Genistein attenuated LPS-induced decrease of the contents of dopamine (DA) and its metabolites in striatum as well as the loss of tyrosine hydroxylase-immunoreactive (TH-IR) neurons in the substantia nigra (SN) of the lesioned side, which could be blocked by GPER antagonist G15 or IGF-1R antagonist JB1. Meanwhile, G15 or JB1 could attenuate the anti-inflammatory effects of genistein in LPS-induced microglial activation and production of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, genistein could inhibit the LPS-induced phosphorylation of p38, JNK, ERK and IκB in the lesioned side of SN and these effects could also be blocked by G15 or JB1. Taken together, our data provide the first evidence that genistein can inhibit the increase of microglia and protect dopaminergic neurons at least in part via GPER and IGF-1R signaling pathways in ovariectomized PD rat model.

The G protein-coupled estrogen receptor (GPER) regulates recognition and aversively–motivated memory in male rats

Estrogens, particularly 17β-estradiol (estradiol, E2), regulate memory formation. E2 acts through its intracellular receptors, estrogen receptors (ER) ERα and ERβ, as well as a recently identified G protein-coupled estrogen receptor (GPER). Although the effects of E2 on memory have been investigated, studies examining the effects of GPER stimulation are scarce. Selective GPER agonism improves memory in ovariectomized female rats, but little information is available regarding the effects of GPER stimulation in male rodents. The aim of the present study was to investigate the effects of the GPER agonist, G1, on consolidation and reconsolidation of inhibitory avoidance (IA) and object recognition (OR) memory in male rats. Animals received vehicle, G1 (15, 75, 150 µg/kg; i.p.), or the GPER antagonist G15 (100 µg/kg; i.p.) immediately after training, or G1 (150 µg/kg; i.p.) 3 or 6 h after training. To investigate reconsolidation, G1 was administered immediately after IA retention Test 1. Results indicated that G1 administered immediately after training at the highest dose enhanced both OR and IA memory consolidation, while GPER blockade immediately after training impaired OR. No effects of GPER stimulation were observed when G1 was given 3 or 6 h after training or after Test 1. The present findings provide evidence that GPER is involved in the early stages of memory consolidation in both neutral and emotional memory tasks in male adult rats.

Anti-inflammatory effect of IGF-1 is mediated by IGF-1R cross talk with GPER in MPTP/MPP+-induced astrocyte activation

Insulin-like growth factor-1 (IGF-1) is a potent neuroprotective polypeptide that exerts neuroprotective effects via the IGF-1 receptor (IGF-1R). Our previous study reported that G protein-coupled estrogen receptor (GPER) was involved in the anti-apoptotic effect of IGF-1. The present study was designed to investigate the anti-inflammatory effect of IGF-1 in association with astrocyte activation and the molecular details of the interaction between IGF-1R and GPER. We showed that IGF-1 could improve 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor deficits and attenuate the upregulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) both in vivo and in vitro. The IGF-1R antagonist JB-1 and the GPER antagonist G15 could antagonize the anti-inflammatory effect of IGF-1. Silencing GPER abrogated the inhibitory effect of IGF-1 on 1-methyl-4-phenylpyridinium (MPP+)-induced upregulation of COX-2 and iNOS in primary astrocytes. Moreover, the MPP + -induced inflammatory response was related to the activation of mitogen-activated protein kinases (MAPKs) and NF-κB signaling pathways. The inhibitory effects of IGF-1 on the phosphorylation of p38, JNK and IκB could be blocked by JB-1. G15 antagonized the inhibitory effects of IGF-1 on p-JNK and p-IκB, but not p-p38. Furthermore, IGF-1 treatment alone increased the expression of GPER, which was blocked by JB-1, the phosphatidylinositol 3-kinase (PI3–K) antagonist LY294002 and the MEK antagonist PD98059 in primary astrocytes. Overall, we show for the first time that GPER may contribute to the anti-inflammatory effect of IGF-1 against MPTP/MPP + -induced astrocyte activation. IGF-1 could regulate the expression of GPER via the IGF-1R/PI3-K/MAPK signaling pathway in primary astrocytes.

IGF-1 inhibits MPTP/MPP+-induced autophagy on dopaminergic neurons through the IGF-1R/PI3K-Akt-mTOR pathway and GPER.

Autophagy dysfunctions are involved in the pathogenesis of Parkinson's disease (PD). In the present study, we aimed to evaluate the involvement of G protein-coupled estrogen receptor (GPER) in the inhibitory effect of insulin-like growth factor-1 (IGF-1) against excessive autophagy in PD animal and cellular models. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment significantly induced mouse movement disorder and decreased the protein level of tyrosine hydroxylase (TH) in the substantia nigra (SN) and dopamine (DA) content in striatum. Along with the dopamine neuron injury, we observed significant upregulations of microtubule-associated light chain-3 II (LC3-II) and α-synuclein as well as a downregulation of P62 in MPTP-treated mice. These changes could be restored by IGF-1 pretreatment. Cotreatment with IGF-1R antagonist JB-1 or GPER antagonist G15 could block the neuroprotective effects of IGF-1. 1-Methy-4-phenylpyridinium (MPP+) treatment could also excessively activate autophagy along with the reduction of cell viability in SH-SY5Y cells. IGF-1 could inhibit the neurotoxicity through promoting the phosphorylation of Akt and mammalian target of rapamycin (mTOR), which could also be antagonized by JB-1 or G15. These data suggest that IGF-1 inhibits MPTP/MPP+-induced autophagy on dopaminergic neurons through the IGF-1R/PI3K-Akt-mTOR pathway and GPER.

Non-genomic mechanisms in the estrogen regulation of glycolytic protein levels in endothelial cells.

Few studies have explored the mechanisms coupling estrogen signals to metabolic demand in endothelial cells. We recently showed that 17β-estradiol (E2) triggers angiogenesis via the membrane G-protein coupled estrogen receptor (GPER) and the key glycolytic protein PFKFB3 as a downstream effector. We herein investigated whether estrogenic agents regulate the stability and/or degradation of glycolytic proteins in human umbilical vein endothelial cells (HUVECs). Similarly to E2, the GPER selective agonist G1 rapidly increased PFKFB3 protein amounts, without affecting mRNA levels. In the presence of cycloheximide, E2 and G1 treatment counteracted PFKFB3 degradation over time, whereas E2-induced PFKFB3 stabilization was abolished by the GPER antagonist G15. Inhibitors of selective SCF E3 ubiquitin ligase (SMER-3) and proteasome (MG132) rapidly increased PFKFB3 protein levels. Accordingly, ubiquitin-bound PFKFB3 was lower in E2- or G1-treated HUVECs. Both agents increased deubiquitinase USP19 levels through GPER signaling. Notably, USP 19 siRNA decreased PFKFB3 levels and abolished E2- and G1-mediated HUVEC tubularization. Finally, E2 and G1 treatments rapidly enhanced glucose transporter GLUT1 levels via GPER independent of transcriptional activation. These findings provide new evidence on mechanisms coupling estrogen signals with the glycolytic program in endothelium and unravel the role of USP19 as a target of the pro-angiogenic effect of estrogenic agents.

17β-Estradiol Inhibits PCSK9-Mediated LDLR Degradation Through GPER/PLC Activation in HepG2 Cells.

Plasma levels of PCSK9 are significantly higher in postmenopausal women. Pharmacologically increased estrogen levels have been shown to lower PCSK9 and LDL-C levels in animals and humans. The action of estrogen suggests that it has the ability to prevent PCSK9-mediated LDLR degradation in liver cells. However, little is known about how estrogen alters PCSK9-mediated LDLR degradation. Here, we report that 17β-estradiol (βE2) reduces PCSK9-mediated LDLR degradation by a mechanism that involves activation of the G protein-coupled estrogen receptor (GPER). In cultured HepG2 cells, βE2 prevented the internalization of PCSK9, which subsequently lead to PCSK9-mediated LDLR degradation. The altered LDLR levels also resulted in an increase in LDL uptake that was not observed in the absence of PCSK9. In addition, we showed that clathrin was rapidly increased in the presence of PCSK9, and this increase was blocked by βE2 incubation, suggesting rapid recruitment of clathrin in HepG2 cells. PLCγ activation and intracellular Ca2+ release were both increased due to the rapid effect of estrogen. By using a GPER antagonist G15, we demonstrated that the GPER mediates the action of estrogen. Together, the data from this in vitro study demonstrate that estrogen can regulate LDLR levels mainly through GPER activation, which prevents PCSK9-dependent LDLR degradation in HepG2 cells.

Activation of the G Protein-Coupled Estrogen Receptor Elicits Store Calcium Release and Phosphorylation of the Mu-Opioid Receptors in the Human Neuroblastoma SH-SY5Y Cells.

Estrogens exert extensive influences on the nervous system besides their well-known roles in regulation of reproduction and metabolism. Estrogens act via the nuclear receptor ERα and ERβ to regulate gene transcription (classical genomic effects). In addition, estrogens are also known to cause rapid non-genomic effects on neuronal functions including inducing fast changes in cytosolic calcium level and rapidly desensitizing the μ type opioid receptor (MOR). The receptors responsible for the rapid actions of estrogens remain uncertain, but recent evidence points to the G protein-coupled estrogen receptor (GPER), which has been shown to be expressed widely in the nervous system. In the current study, we test the hypothesis that activation of GPER may mediate rapid calcium signaling, which may promote phosphorylation of MOR through the calcium-dependent protein kinases in neuronal cells. By qPCR and immunocytochemistry, we found that the human neuroblastoma SH-SY5Y cells endogenously express GPER and MOR. Activation of GPER by 17β-estradiol (E2) and G-1 (GPER selective agonist) evoked a rapid calcium rise in a concentration-dependent manner, which was due to store release rather than calcium entry. The GPER antagonist G15, the PLC inhibitor U73122 and the IP3 receptor inhibitor 2-APB each virtually abolished the calcium responses to E2 or G-1. Activation of GPER stimulated translocation of PKC isoforms (α and ε) to the plasma membrane, which led to MOR phosphorylation. Additionally, E2 and G-1 stimulated c-Fos expression in SH-SY5Y cells in a PLC/IP3-dependent manner. In conclusion, the present study has revealed a novel GPER-mediated estrogenic signaling in neuroblastoma cells in which activation of GPER is followed by rapid calcium mobilization, PKC activation and MOR phosphorylation. GPER-mediated rapid calcium signal may also be transmitted to the nucleus to impact on gene transcription. Such signaling cascade may play important roles in the regulation of opioid signaling in the brain.

Ginsenoside Rg1 Exerts Anti-inflammatory Effects via G Protein-Coupled Estrogen Receptor in Lipopolysaccharide-Induced Microglia Activation.

Neuroinflammation plays a pivotal role in the pathogenesis of Parkinson’s disease. Ginsenoside Rg1, the most active ingredient of ginseng, has been reported to exert neuroprotective effects via estrogen and glucocorticoid receptors. The present study evaluated the involvement of the G protein-coupled estrogen receptor (GPER) in the anti-inflammatory effects of ginsenoside Rg1 against lipopolysaccharide (LPS)-induced microglia activation in the BV2 microglial cell line and ventral mesencephalic primary microglial culture. The pharmacological blockade and lentivirus-mediated small interfering RNA (siRNA) knockdown of GPER were used to study the underlying mechanism. Rg1 attenuated LPS-induced upregulation of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) mRNA and protein levels. The GPER antagonist G15 blocked the inhibitory effects of Rg1 and the GPER-specific agonist G1 on LPS-induced microglia activation. Rg1 mimicked the effects of G1 by inhibiting the LPS-induced activation of nuclear transcription factor-kappa B (NF-κB) and mitogen activated protein kinase signaling pathways, which was also blocked by G15. Moreover, lentivirus-mediated siRNA knockdown of GPER inhibited the anti-inflammatory effects of Rg1. Taken together, our results indicate that GPER is involved in the anti-inflammatory effects of Rg1 against LPS-induced microglia activation. These findings provide a new biological target of Rg1 for the treatment of neuroinflammatory disorders.

Estradiol inhibits fMLP-induced neutrophil migration and superoxide production by upregulating MKP-2 and dephosphorylating ERK

Estrogen has been reported to inhibit neutrophil infiltration related inflammation and suppress neutrophils migration in vitro, but the underlying mechanism is not fully understood. By using HL-60 differentiated neutrophil-like cells (dHL-60) and human neutrophils, we examined the effect of 17-β estradiol (E2) on cell migration and superoxide production in response to chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) and explored the mechanisms involved. We found that fMLP significantly induced dHL-60 cell and neutrophil migration and superoxide production, which was inhibited by ERK inhibitor PD98059. E2 significantly inhibited fMLP-induced dHL-60 cell and neutrophil migration and superoxide production at both physiological and pharmacological concentrations. Mechanistic studies showed that pretreatment of these cells with E2 rapidly elevated the protein level of mitogen-activated protein kinase phosphatase 2 (MKP-2) and inhibited fMLP-induced ERK phosphorylation. Pretreatment of these cells with estrogen receptor (ER) antagonist ICI 182780 reversed the inhibition of fMP-induced cell migration and superoxide production, and the induction of MKP-2 expression and the suppression of fMP-induced ERK phosphorylation by E2. However, pretreatment of cells with G-protein coupled ER antagonist G15 had no such effect. Collectively, these results demonstrate that fMLP stimulates neutrophil chemotaxis and superoxide production through activating ERK, and indicate that ER-mediated upregulation of MKP-2 may dephosphorylate ERK and contribute to the inhibitory effect of E2 on neutrophil activation by fMLP. Our study reveals new mechanisms involved in the anti-inflammatory activity of estrogen.

G protein-coupled estrogen receptor is involved in the anti-inflammatory effects of genistein in microglia

BackgroundGenistein (GEN), a phytoestrogen that is extracted from leguminous plants, can bind to estrogen receptor and exert biological effects. G protein-coupled estrogen receptor (GPER), a novel membrane estrogen receptor, has been reported to be involved in the anti-inflammatory process. In the present study, using BV2 microglial cell line and primary microglial culture, we evaluated the involvement of GPER in the anti-inflammatory effects of genistein against lipopolysaccharide (LPS)-induced microglia activation. MethodsThe anti-inflammatory effects of genistein were investigated in LPS-induced microglial activation in murine BV2 microglial cell line and primary microglial culture. Anti-inflammatory properties of genistein were determined by MTT, real time PCR, ELISA and western blot analysis. The pharmacological blockade and lentivirus-mediated siRNA knockdown of GPER were used to study the underlying mechanism. ResultsThe results showed that genistein exerted inhibitory effects on LPS-induced expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide (iNOS), tumor necrosis factor-α (TNF-α), interleukin-1 β (IL-1β) and interleukin-6 (IL-6). Pre-treatment with GPER antagonist G15 could significantly block the anti-inflammatory effects of genistein. Moreover, the inhibitory effects of genistein on LPS-induced activation of MAPKs and NF-κB signaling pathways could also be blocked by G15. Lentivirus-mediated siRNA knockdown of GPER significantly inhibited the anti-inflammatory effects of genistein in BV2 cells. Further study revealed that genistein treatment could increase the gene and protein expressions of GPER in BV2 cells. ConclusionTaken together, these data provide the first evidence that genistein exerts anti-inflammatory effects in microglial cells via GPER activation. These beneficial effects of genistein may represent a new strategy for the treatment of neuroinflammatory diseases.

GPER Agonist G1 Attenuates Neuroinflammation and Dopaminergic Neurodegeneration in Parkinson Disease

Objective: Epidemiological studies have shown that women of reproductive age have much less possibility of developing Parkinson disease (PD) than men. The beneficial effect of estrogen also has been well-described in both culture and animal models of PD. G protein-coupled estrogen receptor (GPER) is a membrane-associated estrogen receptor, and displayed a neuroprotective role in a mouse model of PD. Since GPER is highly expressed in microglia, we speculate that GPER mediates the neuroprotective function of estradiol through suppressing the neuroinflammation of PD. Methods: We investigated the effects of GPER agonist G1 and GPER antagonist G15 on the neurodegeneration of dopaminergic neuron, the activation of microglia, and the production of IL-1β, TNF-α, and IL-6 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced animal model of parkinsonism. Furthermore, we confirmed the effects of GPER activation on the production of IL-1β, TNF-α, and IL-6 in an in vitro MPP+ model in BV2 microglial cells. Results: After 12-day treatment with G1, mice showed an increase in the number of tyrosine hydroxylase-immunoreactive cells, reduced activation of microglia, and the abatement of proinflammatory cytokines, and the anti-inflammatory effect of G1 was abolished by G15. Meanwhile, in vitro studies demonstrated that GPER activation also reduced the release of proinflammatory cytokines from BV2 microglial cells after MPP+ stimulation. Conclusion: Our data suggest that GPER mediates the anti-neuroinflammatory effect of estrogen in experimental PD progression.

Estrone Sulfate Transport and Steroid Sulfatase Activity in Colorectal Cancer: Implications for Hormone Replacement Therapy.

Hormone replacement therapy (HRT) affects the incidence and potential progression of colorectal cancer (CRC). As HRT primarily consists of estrone sulfate (E1S), understanding whether this conjugated estrogen is transported and metabolized in CRC will define its potential effect in this malignancy. Here, we show that a panel of CRC cell lines (Colo205, Caco2, HCT116, HT-29) have steroid sulfatase (STS) activity, and thus can hydrolyze E1S. STS activity is significantly higher in CRC cell lysate, suggesting the importance of E1S transport in intracellular STS substrate availability. As E1S transport is regulated by the expression pattern of certain solute carrier organic anion transporter polypeptides, we show that in CRC OATP4A1 is the most abundantly expressed transporter. All four CRC cell lines rapidly transported E1S into cells, with this effect significantly inhibited by the competitive OATP inhibitor BSP. Transient knockdown of OATP4A1 significantly disrupted E1S uptake. Examination of estrogen receptor status showed ERα was present in Colo205 and Caco2 cells. None of the cells expressed ERβ. Intriguingly, HCT116 and HT29 cells strongly expressed the G protein coupled estrogen receptor (GPER), and that stimulation of this receptor with estradiol (E2) and G1, a GPER agonist, significantly (p < 0.01) increased STS activity. Furthermore, tamoxifen and fulvestrant, known GPER agonist, also increased CRC STS activity, with this effect inhibited by the GPER antagonist G15. These results suggest that CRC can take up and hydrolyze E1S, and that subsequent GPER stimulation increases STS activity in a potentially novel positive feedback loop. As elevated STS expression is associated with poor prognosis in CRC, these results suggest HRT, tamoxifen and fulvestrant may negatively impact CRC patient outcomes.

Aldosterone induces rapid sodium intake by a nongenomic mechanism in the nucleus tractus solitarius.

The purpose of this study was to determine whether aldosterone has a rapid action in the nucleus tractus solitarius (NTS) that increases sodium intake, and to examine whether this effect of aldosterone, if present, is mediated by G protein-coupled estrogen receptor (GPER). Adult male Sprague-Dawley rats with a stainless-steel cannula in the NTS were used. Aldosterone was injected into the NTS at the doses of 1, 5, 10 and 20 ng 0.1 μl−1. A rapid dose-related increase of 0.3 M NaCl intake was induced within 30 min and this increase was not suppressed by the mineralocorticoid receptor (MR) antagonist spironolactone (10 ng 0.1 μl−1). Water intake was not affected by aldosterone. The GPER agonist G-1 produced a parallel and significant increase in sodium intake, while pre-treatment with GPER antagonist G15 (10 ng 0.1 μl−1) blocked the G-1 or aldosterone-induced rapid sodium intake. In addition, sodium intake induced by sodium depletion or low-sodium diet fell within 30 min after injection into the NTS of the MR antagonist spironolactone, while G15 had no effect. Our results confirm previous reports, and support the hypothesis that aldosterone evokes rapid sodium intake through a non-genomic mechanism involving GPER in NTS.

Aldosterone mediates metastatic spread of renal cancer via the G protein-coupled estrogen receptor (GPER).

Although aldosterone is a known regulator of renal and cardiovascular function, its role as a regulator of cancer growth and spread has not been widely considered. This study tested the hypothesis that aldosterone regulates cancer cell growth/spread via G protein-coupled estrogen receptor (GPER) activation. In vitro in murine renal cortical adenocarcinoma (RENCA) cells, a widely used murine in vitro model for the study of renal cell adenocarcinoma, aldosterone increased RENCA cell proliferation to a maximum of 125 ± 3% of control at a concentration of 10 nM, an effect blocked by the GPER antagonist G15 or by GPER knockdown using short interfering (sh) RNA techniques. Further, aldosterone increased RENCA cell migration to a maximum of 170 ± 20% of control at a concentration of 100 nM, an effect also blocked by G15 or by GPER down-regulation. In vivo, after orthotopic RENCA cell renal transplantation, pulmonary tumor spread was inhibited by pharmacologic blockade of aldosterone effects with spironolactone (percentage of lung occupied by metastasis: control = 68 ± 13, spironolactone = 26 ± 8, P < 0.05) or inhibition of aldosterone synthesis with a high dietary salt diet (percentage of lung: control = 44 ± 6, high salt = 12 ± 3, P < 0.05), without reducing primary tumor size. Additionally, adrenalectomy significantly reduced the extent of pulmonary tumor spread, whereas aldosterone infusion recovered pulmonary metastatic spread toward baseline levels. Finally, inhibition of GPER either with the GPER antagonist G15 or by GPER knockdown comparably inhibited RENCA cell pulmonary metastatic cancer spread. Taken together, these findings provide strong evidence for aldosterone serving a causal role in renal cell cancer regulation via its GPER receptor; thus, antagonism of GPER represents a potential new target for treatment to reduce metastatic spread.-Feldman, R. D., Ding, Q., Hussain, Y., Limbird, L. E., Pickering, J. G., Gros, R. Aldosterone mediates metastatic spread of renal cancer via the G protein-coupled estrogen receptor (GPER).

GPER Mediates Cardiotropic Effects in Spontaneously Hypertensive Rat Hearts

Estrogens promote beneficial effects in the cardiovascular system mainly through the estrogen receptor (ER)α and ERβ, which act as ligand-gated transcription factors. Recently, the G protein-coupled estrogen receptor (GPER) has been implicated in the estrogenic signaling in diverse tissues, including the cardiovascular system. In this study, we demonstrate that left ventricles of male Spontaneously Hypertensive Rats (SHR) express higher levels of GPER compared to normotensive Wistar Kyoto (WKY) rats. In addition, we show that the selective GPER agonist G-1 induces negative inotropic and lusitropic effects to a higher extent in isolated and Langendorff perfused hearts of male SHR compared to WKY rats. These cardiotropic effects elicited by G-1 involved the GPER/eNOS transduction signaling, as determined by using the GPER antagonist G15 and the eNOS inhibitor L-NIO. Similarly, the G-1 induced activation of ERK1/2, AKT, GSK3β, c-Jun and eNOS was abrogated by G15, while L-NIO prevented only the eNOS phosphorylation. In hypoxic Langendorff perfused WKY rat heart preparations, we also found an increased expression of GPER along with that of the hypoxic mediator HIF-1α and the fibrotic marker CTGF. Interestingly, G15 and L-NIO prevented the ability of G-1 to down-regulate the expression of both HIF-1α and CTGF, which were found expressed to a higher extent in SHR compared to WKY rat hearts. Collectively, the present study provides novel data into the potential role played by GPER in hypertensive disease on the basis of its involvement in myocardial inotropism and lusitropism as well as the expression of the apoptotic HIF-1α and fibrotic CTGF factors. Hence, GPER may be considered as a useful target in the treatment of some cardiac dysfunctions associated with stressful conditions like the essential hypertension.