Growth characteristics of HCT116 xenografts lacking asparagine synthetase vary according to sex.

BACKGROUND: Sex-related differences in colorectal (CRC) incidence and mortality are well-documented. However, the impact of sex on metabolic pathways that drive cancer growth is not well understood. High expression of asparagine synthetase (ASNS) is associated with inferior survival for female CRC patients only. Here, we used a CRISPR/Cas9 technology to generate HCT116 ASNS-/- and HCT 116 ASNS+/+ cancer cell lines. We examine the effects of ASNS deletion on tumor growth and the subsequent rewiring of metabolic pathways in male and female Rag2/IL2RG mice. RESULTS: ASNS loss reduces cancer burden in male and female tumor-bearing mice (40% reduction, q < 0.05), triggers metabolic reprogramming including gluconeogenesis, but confers a survival improvement (30 days median survival, q < 0.05) in female tumor-bearing mice alone. Transcriptomic analyses revealed upregulation of G-protein coupled estrogen receptor (GPER1) in tumors from male and female mice with HCT116 ASNS-/- xenograft. Estradiol activates GPER1 in vitro in the presence of ASNS and suppresses tumor growth. CONCLUSIONS: Our study indicates that inferior survival for female CRC patients with high ASNS may be due to metabolic reprogramming that sustains tumor growth. These findings have translational relevance as ASNS/GPER1 signaling could be a future therapeutic target to improve the survival of female CRC patients.

G-protein-coupled estrogen receptor 1 promotes peritoneal metastasis of gastric cancer through nicotinamide adenine dinucleotide kinase 1-mediated redox modulation.

Adipose tissue is the second most important site of estrogen production, where androgens are converted into estrogen by aromatase. While gastric cancer patients often develop adipocyte-rich peritoneal metastasis, the underlying mechanism remains unclear. In this study, we identified the G-protein-coupled estrogen receptor (GPER1) as a promoter of gastric cancer peritoneal metastasis. Functional in vitro studies revealed that ß-Estradiol (E2) or the GPER1 agonist G1 inhibited anoikis in gastric cancer cells. Additionally, genetic overexpression or knockout of GPER1 significantly inhibited or enhanced gastric cancer cell anoikis in vitro and peritoneal metastasis in vivo, respectively. Mechanically, GPER1 knockout disrupted the NADPH pool and increased reactive oxygen species (ROS) generation. Conversely, overexpression of GPER1 had the opposite effects. GPER1 suppressed nicotinamide adenine dinucleotide kinase 1(NADK1) ubiquitination and promoted its phosphorylation, which were responsible for the elevated expression of NADK1 at protein levels and activity, respectively. Moreover, genetic inhibition of NADK1 disrupted NADPH and redox homeostasis, leading to high levels of ROS and significant anoikis, which inhibited lung and peritoneal metastasis in cell-based xenograft models. In summary, our study suggests that inhibiting GPER1-mediated NADK1 activity and its ubiquitination may be a promising therapeutic strategy for peritoneal metastasis of gastric cancer.

Asparagine synthetase and G-protein coupled estrogen receptor are critical responders to nutrient supply in KRAS mutant colorectal cancer.

Survival differences exist in colorectal cancer (CRC) patients by sex and disease stage. However, the potential molecular mechanism(s) are not well understood. Here we show that asparagine synthetase (ASNS) and G protein-coupled estrogen receptor-1 (GPER1) are critical sensors of nutrient depletion and linked to poorer outcomes for females with CRC. Using a 3D spheroid model of isogenic SW48 KRAS wild-type (WT) and G12A mutant (MT) cells grown under a restricted nutrient supply, we found that glutamine depletion inhibited cell growth in both cell lines, whereas ASNS and GPER1 expression were upregulated in KRAS MT versus WT. Estradiol decreased growth in KRAS WT but had no effect on MT cells. Selective GPER1 and ASNS inhibitors suppressed cell proliferation with increased caspase-3 activity of MT cells under glutamine depletion condition particularly in the presence of estradiol. In a clinical colon cancer cohort from The Cancer Genome Atlas, both high GPER1 and ASNS expression were associated with poorer overall survival for females only in advanced stage tumors. These results suggest KRAS MT cells have mechanisms in place that respond to decreased nutrient supply, typically observed in advanced tumors, by increasing the expression of ASNS and GPER1 to drive cell growth. Furthermore, KRAS MT cells are resistant to the protective effects of estradiol under nutrient deplete conditions. The findings indicate that GPER1 and ASNS expression, along with the interaction between nutrient supply and KRAS mutations shed additional light on the mechanisms underlying sex differences in metabolism and growth in CRC, and have clinical implications in the precision management of KRAS mutant CRC.

G protein-coupled estrogen receptor activates PI3K/AKT/mTOR signaling to suppress ferroptosis via SREBP1/SCD1-mediated lipogenesis.

BACKGROUND: Lung cancer is the leading cause of cancer-related death worldwide. The sex differences in the occurrence and fatality rates of non-small cell lung cancer (NSCLC), along with its association with estrogen dependence, suggest that estrogen receptors (ERs) contribute to the development of NSCLC. However, the influence of G protein-coupled estrogen receptor (GPER1) on NSCLC remains to be determined. Escape from ferroptosis is one of the hallmarks of tumor discovered in recent years. In this context, the present study evaluated whether GPER1 promotes NSCLC progression by preventing ferroptosis, and the underlying mechanism through which GPER1 protects against ferroptosis was also explored. METHODS: The effects of GPER1 on the cytotoxicity of H2O2, the ferroptosis inducer RSL3, and Erastin were assessed using the CCK8 assay and plate cloning. Lipid peroxidation levels were measured based on the levels of MDA and BODIPY™581/591C11. GPER1 overexpression and knockdown were performed and G1 was used, and the expression of SCD1 and PI3K/AKT/mTOR signaling factors was measured. Immunofluorescence analysis and immunohistochemistry were performed on paired specimens to measure the correlation between the expression of GPER1 and SCD1 in NSCLC tissues. The effect of GPER1 on the cytotoxicity of cisplatin was measured in vitro using the CCK8 assay and in vivo using xenograft tumor models. RESULTS: GPER1 and G1 alleviated the cytotoxicity of H2O2, reduced sensitivity to RSL3, and impaired lipid peroxidation in NSCLC tissues. In addition, GPER1 and G1 promoted the protein and mRNA expression of SCD1 and the activation of PI3K/AKT/mTOR signaling. GPER1 and SCD1 expression were elevated and positively correlated in NSCLC tissues, and high GPER1 expression predicted a poor prognosis. GPER1 knockdown enhanced the antitumor activity of cisplatin in vitro and in vivo. CONCLUSION: GPER1 prevents ferroptosis in NSCLC by promoting the activation of PI3K/AKT/mTOR signaling, thereby inducing SCD1 expression. Therefore, treatments targeting GPER1 combined with cisplatin would exhibit better antitumor effects.

Estradiol mitigates stress-induced cardiac injury and inflammation by downregulating ADAM17 via the GPER-1/PI3K signaling pathway.

Stress-induced cardiovascular diseases characterized by inflammation are among the leading causes of morbidity and mortality in postmenopausal women worldwide. Estradiol (E2) is known to be cardioprotective via the modulation of inflammatory mediators during stress. But the mechanism is unclear. TNFα, a key player in inflammation, is primarily converted to its active form by 'A Disintegrin and Metalloprotease 17' (ADAM17). We investigated if E2 can regulate ADAM17 during stress. Experiments were performed using female FVB wild-type (WT), C57BL/6 WT, and G protein-coupled estrogen receptor 1 knockout (GPER-1 KO) mice and H9c2 cells. The study revealed a significant increase in cardiac injury and inflammation during isoproterenol (ISO)-induced stress in ovariectomized (OVX) mice. Additionally, ADAM17's membrane content (mADAM17) was remarkably increased in OVX and GPER-1 KO mice during stress. However, in vivo supplementation of E2 significantly reduced cardiac injury, mADAM17, and inflammation. Also, administering G1 (GPER-1 agonist) in mice under stress reduced mADAM17. Further experiments demonstrated that E2, via GPER-1/PI3K pathway, localized ADAM17 at the perinuclear region by normalizing ß1AR-Gαs, mediating the switch from ß2AR-Gαi to Gαs, and reducing phosphorylated kinases, including p38 MAPKs and ERKs. Thus, using G15 and LY294002 to inhibit GPER-1 and its down signaling molecule, PI3K, respectively, in the presence of E2 during stress resulted in the disappearance of E2's modulatory effect on mADAM17. In vitro knockdown of ADAM17 during stress significantly reduced cardiac injury and inflammation, confirming its significant inflammatory role. These interesting findings provide novel evidence that E2 and G1 are potential therapeutic agents for ADAM17-induced inflammatory diseases associated with postmenopausal females.

The hypothalamic paraventricular nucleus as a central hub for the estrogenic modulation of neuroendocrine function and behavior.

Estradiol and hypothalamic paraventricular nucleus (PVN) help coordinate reproduction with body physiology, growth and metabolism. PVN integrates hormonal and neural signals originating in the periphery, generating an output mediated both by its long-distance neuronal projections, and by a variety of neurohormones produced by its magnocellular and parvocellular neurosecretory cells. Here we review the cyto-and chemo-architecture, the connectivity and function of PVN and the sex-specific regulation exerted by estradiol on PVN neurons and on the expression of neurotransmitters, neuromodulators, neuropeptides and neurohormones in PVN. Classical and non-classical estrogen receptors (ERs) are expressed in neuronal afferents to PVN and in specific PVN interneurons, projecting neurons, neurosecretory neurons and glial cells that are involved in the input-output integration and coordination of neurohormonal signals. Indeed, PVN ERs are known to modulate body homeostatic processes such as autonomic functions, stress response, reproduction, and metabolic control. Finally, the functional implications of the estrogenic modulation of the PVN for body homeostasis are discussed.

Orchestrated feedback regulation between melatonin and sex hormones involving GPER1-PKA-CREB signaling in the placenta.

Maintaining placental endocrine homeostasis is crucial for a successful pregnancy. Pre-eclampsia (PE), a gestational complication, is a leading cause of maternal and perinatal morbidity and mortality. Aberrant elevation of testosterone (T0 ) synthesis, reduced estradiol (E2 ), and melatonin productions have been identified in preeclamptic placentas. However, the precise contribution of disrupted homeostasis among these hormones to the occurrence of PE remains unknown. In this study, we established a strong correlation between suppressed melatonin production and decreased E2 as well as elevated T0 synthesis in PE placentas. Administration of the T0 analog testosterone propionate (TP; 2 mg/kg/day) to pregnant mice from E7.5 onwards resulted in PE-like symptoms, along with elevated T0 production and reduced E2 and melatonin production. Notably, supplementation with melatonin (10 mg/kg/day) in TP-treated mice had detrimental effects on fetal and placental development and compromised hormone synthesis. Importantly, E2 , but not T0 , actively enhanced melatonin synthetase AANAT expression and melatonin production in primary human trophoblast (PHT) cells through GPER1-PKA-CREB signaling pathway. On the other hand, melatonin suppressed the level of estrogen synthetase aromatase while promoting the expressions of androgen synthetic enzymes including 17ß-HSD3 and 3ß-HSD1 in PHT cells. These findings reveal an orchestrated feedback mechanism that maintains homeostasis of placental sex hormones and melatonin. It is implied that abnormal elevation of T0 synthesis likely serves as the primary cause of placental endocrine disturbances associated with PE. The suppression of melatonin may represent an adaptive strategy to correct the imbalance in sex hormone levels within preeclamptic placentas. The findings of this study offer novel evidence that identifies potential targets for the development of innovative therapeutic strategies for PE.

Oestrogen receptor-independent actions of oestrogen in cancer.

Oestrogen, the primary female sex hormone, plays a significant role in tumourigenesis. The major pathway for oestrogen is via binding to its receptor [oestrogen receptor (ERα or ß)], followed by nuclear translocation and transcriptional regulation of target genes. Almost 70% of breast tumours are ER + , and endocrine therapies with selective ER modulators (tamoxifen) have been successfully applied. As many as 25% of tamoxifen-treated patients experience disease relapse within 5 years upon completion of chemotherapy. In such cases, the ER-independent oestrogen actions provide a plausible explanation for the resistance, as well as expands the existing horizon of available drug targets. ER-independent oestrogen signalling occurs via one of the following pathways: signalling through membrane receptors, oxidative catabolism giving rise to genotoxic metabolites, effects on mitochondria and redox balance, and induction of inflammatory cytokines. The current review focuses on the non-classical oestrogen signalling, its role in cancer, and its clinical significance.

Different Expression Pattern of G Protein-Coupled Estrogen Receptor GPER1 in Esophageal Squamous Cell Carcinoma and Adenocarcinoma.

Esophageal carcinoma is a male-dominant malignancy worldwide, and esophageal adenocarcinoma (EAC) shows more significant sex bias than esophageal squamous cell carcinoma (ESCC) in morbidity and mortality. The G protein-coupled estrogen receptor 1 (GPER1) is involved in several sex-related cancers; however, its expression level in esophageal carcinoma has been poorly investigated and its role is not precisely defined, depending on histological types. In the present study, the mRNA levels of GPER1 in esophageal carcinoma were collected from GEPIA and Oncomine databases for meta-analyses. The protein expression levels of GPER1 were detected by immunohistochemistry in the tissue microarray of EAC and ESCC. The GPER1 selective agonist G1, antagonist G15, and siRNA were applied in vitro to investigate their impacts on esophageal cell lines. Analysis of the RNA levels from the databases showed a decreased expression of GPER1 in overall esophageal carcinoma, and low expression levels of GPER1 were found to be associated with low survival of tumor patients. However, in the subgroup of EAC and its precancerous lesion, Barrett's esophagus, overexpression of GPER1 RNA was increased when compared with the normal tissues. The average staining scores of GPER1 protein in the tissue microarray of EAC were significantly higher than normal esophageal samples, and the rate of positive staining increased with the grade of poor tumor differentiation. The scores of GPER1 protein in ESCC tissues were lower than those in the normal tissues. The results from cell line experiments in vitro showed that the GPER1 agonist G1 inhibited proliferation and promoted apoptosis of ESCC cells EC109 with positive expression of GPER1. G1 had no obvious effect on normal esophageal NE2 cells with weak expression of GPER1. In addition, GPER1 RNA knockdown and application of antagonist G15 reversed the effects of G1 on EC109. The results of this study indicate that the expression levels of GPER1 are higher in EAC than in ESCC, which might be correlated with the dimorphic estrogen signaling pathway in different types of esophageal carcinoma.

Isoflavones Mediate Dendritogenesis Mainly through Estrogen Receptor α.

The nuclear estrogen receptor (ER) and G-protein-coupled ER (GPER1) play a crucial role during brain development and are involved in dendrite and spine growth as well as synapse formation. Soybean isoflavones, such as genistein, daidzein, and S-equol, a daidzein metabolite, exert their action through ER and GPER1. However, the mechanisms of action of isoflavones on brain development, particularly during dendritogenesis and neuritogenesis, have not yet been extensively studied. We evaluated the effects of isoflavones using mouse primary cerebellar culture, astrocyte-enriched culture, Neuro-2A clonal cells, and co-culture with neurons and astrocytes. Soybean isoflavone-augmented estradiol mediated dendrite arborization in Purkinje cells. Such augmentation was suppressed by co-exposure with ICI 182,780, an antagonist for ERs, or G15, a selective GPER1 antagonist. The knockdown of nuclear ERs or GPER1 also significantly reduced the arborization of dendrites. Particularly, the knockdown of ERα showed the greatest effect. To further examine the specific molecular mechanism, we used Neuro-2A clonal cells. Isoflavones also induced neurite outgrowth of Neuro-2A cells. The knockdown of ERα most strongly reduced isoflavone-induced neurite outgrowth compared with ERß or GPER1 knockdown. The knockdown of ERα also reduced the mRNA levels of ER-responsive genes (i.e., Bdnf, Camk2b, Rbfox3, Tubb3, Syn1, Dlg4, and Syp). Furthermore, isoflavones increased ERα levels, but not ERß or GPER1 levels, in Neuro-2A cells. The co-culture study of Neuro-2A cells and astrocytes also showed an increase in isoflavone-induced neurite growth, and co-exposure with ICI 182,780 or G15 significantly reduced the effects. In addition, isoflavones increased astrocyte proliferation via ER and GPER1. These results indicate that ERα plays an essential role in isoflavone-induced neuritogenesis. However, GPER1 signaling is also necessary for astrocyte proliferation and astrocyte-neuron communication, which may lead to isoflavone-induced neuritogenesis.

Activation of G-Protein-Coupled Estrogen Receptor 1 (GPER1) Reduces Progression of Vulvar Carcinoma Cells.

Whether G protein-coupled estrogen receptor 1 (GPER1) is tumor-promoting or tumor-suppressive depends in part on tumor entity. Little is known about the function of GPER1 in vulvar carcinoma. In this work, we aim to clarify what role GPER1 plays in vulvar cancer, tumor-promoting or tumor-suppressive. Localization of GPER1 in A431 and CAL-39 vulvar carcinoma cells was examined by immunofluorescence. Using a tissue microarray of vulvar neoplasias, the correlation between GPER1 expression and grade of malignancy was investigated. A431 and CAL-39 cells were treated either with GPER1 agonist G1 or antagonist G36. Proliferation was quantified by BrdU assay and viability examined using Resazurin assay. Morphological changes were analyzed by microscopy and measured using ImageJ. Cell migration was analyzed by gap closure assay. Clonogenic potential was tested by colony and sphere formation. Expression of estrogen receptors was examined by Western blot. GPER1 was found consistently expressed in vulvar neoplasia tissues. The immune-reactive score was found to be significantly higher in tissue samples of lymph node metastases and neoplasias with grade 3. In A431 and CAL-39 vulvar carcinoma cells, GPER1 expression was mainly found in the cytoplasm and nuclei. Treatment of A431 and CAL-39 cells with GPER1 agonist G1 resulted in a decrease in proliferation and migration. In addition, colony formation and tumor sphere formation were reduced. Furthermore, morphological signs of necrosis and reduction in cell viability after G1 treatment were observed. The GPER1 antagonist G36 did not have significant effects on vulvar carcinoma cells. Neither agonist G1 nor antagonist G36 treatment resulted in altered expression of estrogen receptors. Activation of GPER1 with GPER1 agonist G1 reduces the tumorigenic potential of the vulvar carcinoma cells. It can be deduced from this that GPER1 appears to have a tumor-suppressive effect in vulvar carcinoma.

Genome-Wide mRNA and Long Non-Coding RNA Analysis of Porcine Trophoblast Cells Infected with Porcine Reproductive and Respiratory Syndrome Virus Associated with Reproductive Failure.

Porcine reproductive and respiratory syndrome (PRRS) is a vertically transmitted reproductive disorder that is typically characterized by miscarriage, premature birth, and stillbirth in pregnant sows after infection. Such characteristics indicate that PRRSV can infect and penetrate the porcine placental barrier to infect fetus piglets. The porcine trophoblast is an important component of the placental barrier, and secretes various hormones, including estrogen and progesterone, to maintain normal pregnancy and embryonic development during pregnancy. It is conceivable that the pathogenic effects of PRRSV infection on porcine trophoblast cells may lead to reproductive failure; however, the underlying detailed mechanism of the interaction between porcine trophoblast (PTR2) cells and PRRSV is unknown. Therefore, we conducted genome-wide mRNA and long non-coding RNA (lncRNA) analysis profiling in PRRSV-infected PTR2. The results showed that 672 mRNAs and 476 lncRNAs were significantly different from the control group after viral infection. Target genes of the co-expression and co-location of differential mRNAs and lncRNAs were enriched by GO (gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis, revealing that most of the pathways were involved in cell nutrient metabolism, cell proliferation, and differentiation. Specifically, the estrogen signaling pathway, the PI3K (PhosphoInositide-3 Kinase)-Akt (serine/threonine kinase) signaling pathway, and the insulin secretion related to embryonic development were selected for analysis. Further research found that PRRSV inhibits the expression of G-protein-coupled estrogen receptor 1 (GPER1), thereby reducing estrogen-induced phosphorylation of AKT and the mammalian target of rapamycin (mTOR). The reduction in the phosphorylation of AKT and mTOR blocks the activation of the GPER1- PI3K-AKT-mTOR signaling pathway, consequently restraining insulin secretion, impacting PTR2 cell proliferation, differentiation, and nutrient metabolism. We also found that PRRSV triggered trophoblast cell apoptosis, interrupting the integrity of the placental villus barrier. Furthermore, the interaction network diagram of lncRNA, regulating GPER1 and apoptosis-related genes, was constructed, providing a reference for enriching the functions of these lncRNA in the future. In summary, this article elucidated the differential expression of mRNA and lncRNA in trophoblast cells infected with PRRSV. This infection could inhibit the PI3K-AKT-mTOR pathway and trigger apoptosis, providing insight into the mechanism of the vertical transmission of PRRSV and the manifestation of reproductive failure.

G protein-coupled estrogen receptor (GPER/GPR30) levels in pelvic floor muscles and its association with estrogen status in female rabbits.

Objective: To assess the relative expression of the G-protein coupled estrogen receptor (GPER) in the bulbospongiosus (Bsm) and pubococcygeus (Pcm) muscles in control, ovariectomized (OVX), and OVX with estradiol benzoate supplementation (OVX + EB) rabbits.Methods: We used tissues from C, 1-month OVX, and OVX plus 15-day EB implanted (OVX + EB) groups. The GPER expression was evaluated by Western blot and immunohistochemistry for both Bsm and Pcm. Results: Both muscles showed a GPER immunoreactivity in blood vessels, inside myofibers next to myonuclei, and in polymorphonuclear cells. Four-week ovariectomy did not modify the GPER expression in the Bsm and Pcm, but two-week estradiol benzoate increased it in the latter muscle alone.Conclusions: We demonstrated that the Bsm and Pcm of female rabbits express GPER. High serum estradiol levels elevate GPER relative expression in the Pcm alone. The present study supports the remarkable estrogen sensitivity of the Pcm.

LncRNA CEBPA-AS1 knockdown prevents neuronal apoptosis against oxygen glucose deprivation/reoxygenation by regulating the miR-455/GPER1 axis.

Ischemic stroke (IS) is a common nervous system disease, which is a major cause of disability and death in the world. In present study, we demonstrated a regulatory mechanism of CCAAT/enhancer binding protein-alpha antisense 1 (CEBPA-AS1) in oxygen glucose deprivation/reoxygenation (OGD/R)-induced SH-SY5Y cells, with a focus on neuronal apoptosis. CEBPA-AS1, miR-455, and GPER1 expressions were evaluated by using qRT-PCR and Western blotting. The binding relationship among CEBPA-AS1, miR-455, and GPER1 was determined by a dual luciferase reporter assay. Neuronal viability and apoptosis were examined using MTT and flow cytometry assays, followed by determination of apoptosis-related factors (caspase 3, caspase 8, caspase 9, Bax, and Bcl-2). CEBPA-AS1 and GPER1 levels were upregulated, and miR-455 level was downregulated in the cell model of OGD/R induced. CEBPA-AS1 knockdown increased SH-SY5Y viability and reduced OGD/R-induced apoptosis. CEBPA-AS1 could act as a sponge of miR-455, and CEBPA-AS1 knockdown was found to elevate miR-455 expression. miR-455 overexpression also promoted SH-SY5Y cell viability and rescued them from OGD/R-induced apoptosis by binding to GPER1. GPER1 overexpression or miR-455 inhibition reversed the anti-apoptotic effect of CEBPA-AS1 knockdown. These findings suggest a regulatory network of CEBPA-AS1/miR-455/GPER1 that mediates neuronal cell apoptosis in the OGD model, providing a better understanding of pathogenic mechanisms after IS.

Emerging Therapeutic Targets for Heart Failure.

PURPOSE OF REVIEW: Heart failure is a global epidemic that affects at least 26 million individuals globally and is becoming more prevalent. Despite advances in treatment strategies, survival and symptom management in individuals with heart failure remain exceptionally low. This review discusses emerging targets for the treatment of heart failure. RECENT FINDINGS: Recently, a number of targets are being investigated as prospective treatment possibilities for heart failure. These include targets like Runx1 transcription factor (RUNX1), milk fact globule-EFG factor 8 (MFGE8) protein and enzymes such as neuraminidase 1 (NEU1), G protein-coupled receptor kinase 5 (GRK5), G protein-coupled oestrogen receptor 1 (GPER1), urotensin-II receptor (UTR), cluster of differentiation 47 (CD47) and relaxin receptor 1 (RXFP1). On a worldwide level, heart failure is a developing epidemic with substantial morbidity and death. The number of individuals diagnosed with chronic heart failure is rising, and it is anticipated to surge by 46% by 2030. Appropriate heart failure treatment can have the greatest influence on prolonging patients' lives in the coming year. Targets discussed in this review may provide new therapeutic approaches for the treatment of heart failure.

G protein-coupled estrogen receptor-1 enhances excitatory synaptic responses in the entorhinal cortex.

Activation of estrogen receptors is thought to modulate cognitive function in the hippocampus, prefrontal cortex, and striatum by affecting both excitatory and inhibitory synaptic transmission. The entorhinal cortex is a major source of cortical sensory and associational input to the hippocampus, but it is unclear whether either estrogens or progestogens may modulate cognitive function through effects on synaptic transmission in the entorhinal cortex. This study assessed the effects of the brief application of either 17-ß estradiol (E2) or progesterone on excitatory glutamatergic synaptic transmission in the female rat entorhinal cortex in vitro. Rats were ovariectomized on postnatal day (PD) 63 and also received subdermal E2 implants to maintain constant low levels of circulating E2 on par with estrus. Electrophysiological recordings from brain slices were obtained between PD70 and PD86, and field excitatory postsynaptic potentials (fEPSPs) reflecting the activation of the superficial layers of the entorhinal cortex were evoked by the stimulation of layer I afferents. The application of E2 (10 nM) for 20 min resulted in a small increase in the amplitude of fEPSPs that reversed during the 30-min washout period. The application of the ERα agonist propylpyrazoletriol (PPT) (100 nM) or the ß agonist DPN (1 µM) did not significantly affect synaptic responses. However, the application of the G protein-coupled estrogen receptor-1 (GPER1) agonist G1 (100 nM) induced a reversible increase in fEPSP amplitude similar to that induced by E2. Furthermore, the potentiation of responses induced by G1 was blocked by the GPER1 antagonist G15 (1 µM). Application of progesterone (100 nM) or its metabolite allopregnanolone (1 µM) did not significantly affect synaptic responses. The potentiation of synaptic transmission in the entorhinal cortex induced by the activation of GPER1 receptors may contribute to the modulation of cognitive function in female rats.

Activation of G-protein coupled estradiol receptor 1 in the dorsolateral striatum attenuates preference for cocaine and saccharin in male but not female rats.

There are sex differences in the response to psychomotor stimulants, where females exhibit a greater response than males, due to the presence of the gonadal hormone estradiol (E2). Extensive research has shown that E2 enhances drug-seeking and the rewarding properties of cocaine for females. The role of E2 in male drug-seeking, however, is not well understood. The current study investigated pharmacological manipulation of E2 receptors in the dorsolateral striatum (DLS) on preference for cocaine in gonad-intact male and female rats. In males, activation of G-protein coupled E2 receptor 1 (GPER1), via administration of ICI 182,780 or G1, attenuated conditioned place preference for 10 mg/kg cocaine, while inhibition of GPER1, via G15, enhanced preference at a 5 mg/kg cocaine dose. Similarly, GPER1 activation, via G1, prevented males from forming a preference for 0.1% saccharin (SACC) versus plain water. Surprisingly, activation of GPER1 did not alter preference for cocaine or SACC in females. These studies also examined the quantity of E2 receptor mRNA in the dorsal striatum, using qPCR. No sex differences in relative mRNA expression of ERα, ERß, and GPER1 were observed. However, there was greater GPER1 mRNA, relative to ERα and ERß, in both males and females. The results presented here indicate that E2, acting via GPER1, may be protective against drug preference in male rats.

GPER1 Modulates Synaptic Plasticity During the Development of Temporal Lobe Epilepsy in Rats.

G-protein coupled estrogen receptor 1 (GPER1) is a novel type of estrogen receptor. Several studies have shown that it has an anti-inflammatory action,which plays an important role in remyelination and cognitive ability adjustment. However, whether it is involved in the development of temporal lobe epilepsy (TLE) is still unknown. The present study established a TLE model by intraperitoneal injection of lithium chloride (3 mmol/kg) and pilocarpine (50 mg/kg) in rats to study the effect of GPER1 in the synaptic plasticity during the development of temporal lobe epilepsy. A microinjection cannula was implanted into the lateral ventricle region of rats via a stereotaxic instrument. G-1 is the specific GPER1 agonist and G15 is the specific GPER1 antagonist. The G1 or G15 and Dimethyl sulfoxide were injected into the rat brains in the intervention groups and control group, respectively. After G1 intervention, the learning and memory abilities and hippocampal neuron damage in epileptic rats were significantly improved, while G15 weakened the neuroprotective effect of GPER1. Meanwhile, G1 controlled the abnormal formation of hippocampal mossy fiber sprouting caused by seizures, and participated in the regulation of synaptic plasticity by reducing the expression of Synapsin I and increasing the expression of gephyrin. Inhibitory synapse gephyrin may play a significant role in synaptic plasticity.

Saikosaponin-d alleviates hepatic fibrosis through regulating GPER1/autophagy signaling.

BACKGROUND: Hepatic fibrosis is the final pathway of chronic liver disease characterized by excessive accumulation of extracellular matrix (ECM), which eventually develop into cirrhosis and liver cancer. Emerging studies demonstrated that Saikosaponin-d (SSd) exhibits a protective role in liver fibrosis. However, the mechanism underlying anti-liver fibrosis of SSd in vivo and in vitro remains unclear. METHODS AND RESULTS: Transforming growth factor (TGF)-ß and carbon tetrachloride (CCl4) were used for creating liver fibrosis model in vitro and in vivo, respectively. The role of SSd in regulating liver fibrosis was assessed through Sirius red and Masson staining, and IHC assay. We found that SSd attenuated remarkably CCl4-induced liver fibrosis as evidenced by decreased collagen level, and decreased expression of fibrotic markers Col 1 and α-SMA. Meanwhile, SSd repressed autophagy activation as suggested by decreased BECN1 expression and increased p62 expression. Compared with HSCs from CCl4-treated group, the primary HSCs from SSd-treated mice exhibited a marked inactivation of autophagy. Mechanistically, SSd treatment enhanced the expression of GPER1 in primary HSCs and in TGF-ß-treated LX-2 cells. GPER1 agonist G1 repressed autophagy activation, whereas GPER1 antagonist G15 activated autophagy and G15 also damaged the function of SSd on suppressing autophagy, leading to subsequent increased levels of fibrotic marker level in LX-2 cells. CONCLUSIONS: Our findings highlight that SSd alleviates hepatic fibrosis by regulating GPER1/autophagy pathway.

4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) Targets Estrogen Receptor ß, to Evoke the Resistance of Human Breast Cancer MCF-7 Cells to G-1, an Agonist for G Protein-Coupled Estrogen Receptor 1.

Bisphenol A (BPA) has been shown to induce the activation of nuclear estrogen receptor α/ß (ERα/ß) in both in vitro and in vivo settings. We originally obtained a 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a possible active metabolite of BPA, strongly activating the ERs-mediated transcription in MCF-7 cells with an EC50 of 2.8 nM (i.e., BPA's EC50 = 519 nM). Environmental estrogens can also target G protein-coupled estrogen receptor 1 (GPER1), a membrane-type ER. However, the effects of BPA/MBP on GPER1, have not yet been fully resolved. In this study, we used MCF-7, a ERα/ERß/GPER1-positive human breast cancer cell line, as a model to investigate the effects of the exposure to BPA or MBP. Our results revealed that at concentrations below 1 nM MBP, but not BPA, downregulates the expression of GPER1 mRNA via upregulated ERß, and the MCF-7 cells pre-treated with MBP display resistance to GPER1 agonist G-1-mediated anti-proliferative effects. Because GPER1 can act as a tumor suppressor in several types of cancer including breast cancer, the importance of MBP-mediated decrease in GPER1 expression in breast cancer cells is discussed.