G protein-coupled estrogen receptor expression in postnatal developing mouse retina.

Introduction: Estrogen has emerged as a multifaceted signaling molecule in the retina, playing an important role in neural development and providing neuroprotection in adults. It interacts with two receptor types: classical estrogen receptors (ERs) alpha and beta, and G protein-coupled estrogen receptor (Gper). Gper differs from classical ERs in structure, localization, and signaling. Here we provide the first report of the temporal and spatial properties of Gper transcript and protein expression in the developing and mature mouse retina. Methods: We applied qRT-PCR to determine Gper transcript expression in wild type mouse retina from P0-P21. Immunohistochemistry and Western blot were used to determine Gper protein expression and localization at the same time points. Results: Gper expression showed a 6-fold increase during postnatal development, peaking at P14. Relative total Gper expression exhibited a significant decrease during retinal development, although variations emerged in the timing of changes among different forms of the protein. Gper immunoreactivity was seen in retinal ganglion cells (RGCs) throughout development and also in somas in the position of horizontal cells at early time points. Immunoreactivity was observed in the cytoplasm and Golgi at all time points, in the nucleus at early time points, and in RGC axons as the retina matured. Discussion: In conclusion, our study illuminates the spatial and temporal expression patterns of Gper in the developing mouse retina and provides a vital foundation for further investigations into the role of Gper in retinal development and degeneration.

Joint Inflammation Correlates with Joint GPR30 Expression in Males and Hippocampal GPR30 Expression in Females in a Rat Model of Rheumatoid Arthritis.

It is not entirely clear how the interaction between joint inflammation and the central nervous system (CNS) response in rheumatoid arthritis (RA) works, and what pathophysiology underlies the sex differences in coexisting neuropsychiatric comorbidities. It is known that estrogen hormones reduce inflammation in RA and that this occurs mainly via the stimulation of G protein-coupled receptor-30 (GPR30), also known as G protein-coupled estrogen receptor (GPER) 1. However, changes in GPR30 expression and sex differences induced by local and systemic inflammation in RA are not yet known. Our aim was to reveal sex differences in the expression and association of joint GPR30 with local and systemic inflammation, clinical course and furthermore with hippocampal GPR30 expression during pristane-induced arthritis (PIA) in Dark Agouti (DA) rats, an animal model of RA. Furthermore, we demonstrated sex-specific differences in the association between joint and systemic inflammation and hippocampal microglia during PIA. Our results suggest sex-specific differences not only in the clinical course and serum levels of pro-inflammatory cytokines but also in the expression of GPR30. Female rats show greater synovial inflammation and greater damage to the articular cartilage compared to males during PIA attack. Male rats express higher levels of synovial and cartilaginous GPR30 than females during PIA, which correlates with a less severe clinical course. The correlation between synovial and cartilaginous GPR30 and joint inflammation scores (Krenn and Mankin) in male rats suggests that the more severe the joint inflammation, the higher the GPR30 expression. At the same time, there is no particular upregulation of hippocampal GPR30 in males. On the other hand, female rats express higher levels of neuroprotective GPR30 in the hippocampus than male rats at the basic level and during PIA attack. In addition, females have a higher number of Iba-1+ cells in the hippocampus during PIA attack that strongly correlates with the clinical score, serum levels of IL-17A, and Krenn and Mankin scores. These results suggest that male rats are better protected from inflammation in the joints and female rats are better protected from the inflammation in the hippocampus during a PIA attack, independently of microglia proliferation. However, in the remission phase, synovial GPR30 expression suddenly increases in female rats, as does hippocampal GPR30 expression in males. Further experiments with a longer remission period are needed to investigate the molecular background of these sex differences, as well as microglia phenotype profiling.

Activation of GPER1 by G1 prevents PTSD-like behaviors in mice: Illustrating the mechanisms from BDNF/TrkB to mitochondria and synaptic connection.

BACKGROUND: G1 is a specific agonist of G protein-coupled estrogen receptor 1 (GPER1), which binds and activates GPER1 to exert various neurological functions. However, the preventive effect of G1 on post-traumatic stress disorder (PTSD) and its mechanisms are unclear. OBJECTIVE: To evaluate the protective effect of G1 against synaptic and mitochondrial impairments and to investigate the mechanism of G1 to improve PTSD from brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB) signaling. METHODS: This study initially detected GPER1 expression in the hippocampus of single prolonged stress (SPS) mice, utilizing both Western blot and immunofluorescence staining. Subsequently, the effects of G1 on PTSD-like behaviors, synaptic, and mitochondrial functions in SPS mice were investigated. Additionally, the involvement of BDNF/TrkB signaling involved in the protection was further confirmed using GPER1 antagonist and TrkB inhibitor, respectively. RESULTS: The expression of GPER1 was reduced in the hippocampus of SPS mice, and G1 treatment given for 14 consecutive days significantly improved PTSD-like behaviors in SPS mice compared with model group. Electrophysiological local field potential (LFP) results showed that G1 administration for 14 consecutive days could reverse the abnormal changes in the gamma oscillation in the CA1 region of SPS mice. Meanwhile, G1 administration for 14 consecutive days could significantly improve the abnormal expression of synaptic proteins, increase the expression of mitochondria-related proteins, increase the number of synapses in the hippocampus, and ameliorate the damage of hippocampal mitochondrial structure in SPS mice. In addition, G15 (GPER1 inhibitor) and ANA-12 (TrkB inhibitor) blocked the ameliorative effects of G1 on PTSD-like behaviors and aberrant expression of hippocampal synaptic and mitochondrial proteins in SPS mice and inhibited the reparative effects of G1 on structural damage to hippocampal mitochondria, respectively. CONCLUSION: G1 improved PTSD-like behaviors in SPS mice, possibly by increasing hippocampal GPER1 expression and promoting BDNF/TrkB signaling to repair synaptic and mitochondrial functional impairments. This study would provide critical mechanism for the prevention and treatment of PTSD.

The G Protein Estrogen Receptor (GPER) is involved in the resistance to the CDK4/6 inhibitor palbociclib in breast cancer.

BACKGROUND: The cyclin D1-cyclin dependent kinases (CDK)4/6 inhibitor palbociclib in combination with endocrine therapy shows remarkable efficacy in the management of estrogen receptor (ER)-positive and HER2-negative advanced breast cancer (BC). Nevertheless, resistance to palbociclib frequently arises, highlighting the need to identify new targets toward more comprehensive therapeutic strategies in BC patients. METHODS: BC cell lines resistant to palbociclib were generated and used as a model system. Gene silencing techniques and overexpression experiments, real-time PCR, immunoblotting and chromatin immunoprecipitation studies as well as cell viability, colony and 3D spheroid formation assays served to evaluate the involvement of the G protein-coupled estrogen receptor (GPER) in the resistance to palbociclib in BC cells. Molecular docking simulations were also performed to investigate the potential interaction of palbociclib with GPER. Furthermore, BC cells co-cultured with cancer-associated fibroblasts (CAFs) isolated from mammary carcinoma, were used to investigate whether GPER signaling may contribute to functional cell interactions within the tumor microenvironment toward palbociclib resistance. Finally, by bioinformatics analyses and k-means clustering on clinical and expression data of large cohorts of BC patients, the clinical significance of novel mediators of palbociclib resistance was explored. RESULTS: Dissecting the molecular events that characterize ER-positive BC cells resistant to palbociclib, the down-regulation of ERα along with the up-regulation of GPER were found. To evaluate the molecular events involved in the up-regulation of GPER, we determined that the epidermal growth factor receptor (EGFR) interacts with the promoter region of GPER and stimulates its expression toward BC cells resistance to palbociclib treatment. Adding further cues to these data, we ascertained that palbociclib does induce pro-inflammatory transcriptional events via GPER signaling in CAFs. Of note, by performing co-culture assays we demonstrated that GPER contributes to the reduced sensitivity to palbociclib also facilitating the functional interaction between BC cells and main components of the tumor microenvironment named CAFs. CONCLUSIONS: Overall, our results provide novel insights on the molecular events through which GPER may contribute to palbociclib resistance in BC cells. Additional investigations are warranted in order to assess whether targeting the GPER-mediated interactions between BC cells and CAFs may be useful in more comprehensive therapeutic approaches of BC resistant to palbociclib.

Estetrol/GPER/SERPINB2 transduction signaling inhibits the motility of triple-negative breast cancer cells.

BACKGROUND: Estetrol (E4) is a natural estrogen produced by the fetal liver during pregnancy. Due to its favorable safety profile, E4 was recently approved as estrogenic component of a new combined oral contraceptive. E4 is a selective ligand of estrogen receptor (ER)α and ERß, but its binding to the G Protein-Coupled Estrogen Receptor (GPER) has not been described to date. Therefore, we aimed to explore E4 action in GPER-positive Triple-Negative Breast Cancer (TNBC) cells. METHODS: The potential interaction between E4 and GPER was investigated by molecular modeling and binding assays. The whole transcriptomic modulation triggered by E4 in TNBC cells via GPER was explored through high-throughput RNA sequencing analyses. Gene and protein expression evaluations as well as migration and invasion assays allowed us to explore the involvement of the GPER-mediated induction of the plasminogen activator inhibitor type 2 (SERPINB2) in the biological responses triggered by E4 in TNBC cells. Furthermore, bioinformatics analysis was aimed at recognizing the biological significance of SERPINB2 in ER-negative breast cancer patients. RESULTS: After the molecular characterization of the E4 binding capacity to GPER, RNA-seq analysis revealed that the plasminogen activator inhibitor type 2 (SERPINB2) is one of the most up-regulated genes by E4 in a GPER-dependent manner. Worthy, we demonstrated that the GPER-mediated increase of SERPINB2 is engaged in the anti-migratory and anti-invasive effects elicited by E4 in TNBC cells. In accordance with these findings, a correlation between SERPINB2 levels and a good clinical outcome was found in ER-negative breast cancer patients. CONCLUSIONS: Overall, our results provide new insights into the mechanisms through which E4 can halt migratory and invasive features of TNBC cells.

Analysis of Binding Modes between Three Perfluorosulfonates and GPER Based on Computational Simulation and Multiple Spectral Methods.

Perfluorinated compounds (PFCs) belong to a significant category of global environmental pollutants. Investigating the toxicological effects of PFCs within biological systems is of critical significance in various disciplines such as life sciences, environmental science, chemistry, and ecotoxicology. In this study, under simulated human physiological conditions (pH = 7.4), a combination of multiple spectroscopic techniques and computational simulations was employed to investigate the impact of perfluorinated compounds (PFCs) on the G protein-coupled estrogen receptor (GPER). Additionally, the research focused on exploring the binding modes and toxicological mechanisms between PFCs and GPER at the molecular level. All three perfluorinated sulfonic acids (PFSAs) can induce quenching of GPER fluorescence through static quenching and non-radiative energy transfer. Steady-state fluorescence calculations at different temperatures revealed apparent binding constants in the order of 106, confirming a strong binding affinity between the three PFSAs and GPER. Molecular docking studies indicated that the binding sites of PFSAs are located within the largest hydrophobic cavity in the head region of GPER, where they can engage in hydrogen bonding and hydrophobic interactions with amino acid residues within the cavity. Fourier transform infrared spectroscopy, three-dimensional fluorescence, and molecular dynamics simulations collectively indicate that proteins become more stable upon binding with small molecules. There is an overall increase in hydrophobicity, and alterations in the secondary structure of the protein are observed. This study deepens the comprehension of the effects of PFCs on the endocrine system, aiding in evaluating their potential impact on human health. It provides a basis for policy-making and environmental management while also offering insights for developing new pollution monitoring methods and drug therapies.

Exploring the physiological role of the G protein-coupled estrogen receptor (GPER) and its associations with human diseases.

Estrogen is a group of hormones that collaborate with the nervous system to impact the overall well-being of all genders. It influences many processes, including those occurring in the central nervous system, affecting learning and memory, and playing roles in neurodegenerative diseases and mental disorders. The hormone's action is mediated by specific receptors. Significant roles of classical estrogen receptors, ERα and ERß, in various diseases were known since many years, but after identifying a structurally and locationally distinct receptor, the G protein-coupled estrogen receptor (GPER), its role in human physiology and pathophysiology was investigated. This review compiles GPER-related information, highlighting its impact on homeostasis and diseases, while putting special attention on functions and dysfunctions of this receptor in neurobiology and biobehavioral processes. Understanding the receptor modulation possibilities is essential for therapy, as disruptions in receptors can lead to diseases or disorders, irrespective of correct estrogen levels. We conclude that studies on the GPER receptor have the potential to develop therapies that regulate estrogen and positively impact human health.

Triclocarban and triclosan promote breast cancer progression in vitro and in vivo via activating G protein-coupled estrogen receptor signaling pathways.

Triclocarban (TCC) and triclosan (TCS) have been detected ubiquitously in human body and evoked increasing concerns. This study aimed to reveal the induction risks of TCC and TCS on triple negative breast cancer through non-genomic GPER-mediated signaling pathways. Molecular simulation indicated that TCC exhibited higher GPER binding affinity than TCS theoretically. Calcium mobilization assay displayed that TCC/TCS activated GPER signaling pathway with the lowest observed effective concentrations (LOEC) of 10 nM/100 nM. TCC and TCS also upregulated MMP-2/9, EGFR, MAPK3 but downregulated MAPK8 via GPER-mediated signaling pathway. Proliferation assay showed that TCC/TCS induced 4 T1 breast cancer cells proliferation with the LOEC of 100 nM/1000 nM. Wound-healing and transwell assays showed that TCC/TCS promoted 4 T1 cells migration in a concentration-dependent manner with the LOEC of 10 nM. The effects of TCC on breast cancer cells proliferation and migration were stronger than TCS and both were regulated by GPER. TCC/TCS induced migratory effects were more significantly than proliferative effect. Mechanism study showed that TCC/TCS downregulated the expression of epithelial marker (E-cadherin) but upregulated mesenchymal markers (snail and N-cadherin), which was reversed by GPER inhibitor G15. These biomarkers results indicated that TCC/TCS-induced 4 T1 cells migration was a classic epithelial to mesenchymal transition mechanism regulated by GPER signaling pathway. Orthotopic tumor model verified that TCC promoted breast cancer in-situ tumor growth and distal tissue metastasis via GPER-mediated signaling pathway at human-exposure level of 10 mg/kg/d. TCC-induced tissue metastasis of breast cancer was more significantly than in-situ tumor growth. Overall, we demonstrated for the first time that TCC/TCS could activate the GPER signaling pathways to induce breast cancer progression.

Targeting the crosstalk between estrogen receptors and membrane growth factor receptors in breast cancer treatment: Advances and opportunities.

Estrogens play a critical role in the initiation and progression of breast cancer. Estrogen receptor (ER)α, ERß, and G protein-coupled estrogen receptor are the primary receptors for estrogen in breast cancer. These receptors are mainly activated by binding with estrogens. The crosstalk between ERs and membrane growth factor receptors creates additional pathways that amplify the effects of their ligands and promote tumor growth. This crosstalk may cause endocrine therapy resistance in ERα-positive breast cancer. Furthermore, this may explain the resistance to anti-human epidermal growth factor receptor-2 (HER2) treatment in ERα-/HER2-positive breast cancer and chemotherapy resistance in triple-negative breast cancer. Accordingly, it is necessary to understand the complex crosstalk between ERs and growth factor receptors. In this review, we delineate the crosstalk between ERs and membrane growth factor receptors in breast cancer. Moreover, this review highlights the current progress in clinical treatment and discusses how pharmaceuticals target the crosstalk. Lastly, we discuss the current challenges and propose potential solutions regarding the implications of targeting crosstalk via pharmacological inhibition. Overall, the present review provides a landscape of the crosstalk between ERs and membrane growth factor receptors in breast cancer, along with valuable insights for future studies and clinical treatments using a chemotherapy-sparing regimen to improve patient quality of life.

The beneficial roles and mechanisms of estrogens in immune health and infection disease.

Multiple epidemiologic studies have revealed that gender is considered one of the important factors in the frequency and severity of certain infectious diseases, in which estrogens may play a vital role. There is growing evidence that estrogens as female sex hormone can modulate multiple biological functions outside of the reproductive system, such as in brain and cardiovascular system. However, it is largely unknown about the roles and mechanisms of estrogens/estrogen receptors in immune health and infection disease. Thence, by reading a lot of literature, we summarized the regulatory mechanisms of estrogens/estrogen receptors in immune cells and their roles in certain infectious diseases with gender differences. Therefore, estrogens may have therapeutic potentials to prevent and treat these infectious diseases, which needs further clinical investigation.

Modulation of GPER1 alleviates early brain injury via inhibition of A1 reactive astrocytes activation after intracerebral hemorrhage in mice.

Background: Early brain injury (EBI) caused by inflammatory responses in acute phase of Intracerebral hemorrhage (ICH) plays a vital role in the pathological progression of ICH. Increasing evidences demonstrate A1 reactive astrocytes are associated with the severity of EBI. G-protein coupled estrogen receptor 1 (GPER1) has been proved mediating the neuroprotective effects of estrogen in central nervous system (CNS) disease. However, whether GPER1 plays a protective effect on ICH and A1 reactive astrocytes activation is not well studied. Methods: ICH model was established by infused the autologous whole blood into the right basal ganglia in wild type and GPER1 knockout mice. GPER1 specific agonist G1 and antagonist G15 were administered by intraperitoneal injection at 1 h or 0.5 h after ICH. Neurological function was detected on day 1 and day 3 by open field test and corner turn test following ICH. Besides, A1 reactive astrocytes were determined by immunofluorescence staining after ICH on day 3. To further identify the possible mechanism of GPER1 mediated neuroprotective effect, Western blot assays was performed after ICH on day 3. Results: After ICH, G1 treatment alleviated mice neurobehavior deficits on day 1 and day 3. Meanwhile, G1 treatment also significantly reduced the GFAP positive astrocytes and the C3 positive cells after ICH. Interestingly, G15 reversed the protective effect of G1 on the neurobehavior of ICH mice. Meanwhile, the expression of GFAP+C3+ A1 reactive astrocytes were also reduced by activation of GPER1. Mechanistic studies indicated TLR4 and NF-κB mediated the neuroprotective effect of GPER1. Conclusion: Generally, activation of GPER1 alleviated the EBI through inhibiting A1 reactive astrocytes activation via TLR4/NF-κB pathway after ICH in mice. Additionally, GPER1may be a promising target for ICH treatment.

Current progress and prospects for G protein-coupled estrogen receptor in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a biologically and clinically heterogeneous disease. The G protein-coupled estrogen receptor (GPER) plays a crucial role in mediating the effect of estrogen and estrogen-like compounds in TNBC cells. Compared with other subtypes, GPER has a higher expression in TNBC. The GPER mechanisms have been thoroughly characterized and analyzed in estrogen receptor α (ERα) positive breast cancer, but not in TNBC. Our previous work revealed that a higher expression of GPER mRNA indicates a better prognosis for ERα-positive breast cancer; however, its effects in TNBC differ. Whether GPER could serve as a predictive prognostic marker or therapeutic target for TNBC remains unclear. In this review, we provide a detailed introduction to the subcellular localization of GPER, the different effects of various ligands, and the interactions between GPER and closely associated factors in TNBC. We focused on the internal molecular mechanisms specific to TNBC and thoroughly explored the role of GPER in promoting tumor development. We also discussed the interaction of GPER with specific cytokines and chemokines, and the relationship between GPER and immune evasion. Additionally, we discussed the feasibility of using GPER as a therapeutic target in the context of existing studies. This comprehensive review highlights the effects of GPER on TNBC, providing a framework and directions for future research.

Baohuoside I suppresses the NLRP3 inflammasome activation via targeting GPER to fight against Parkinson's disease.

BACKGROUND: Accumulating evidence indicates the crucial role of microglia-mediated inflammation and the NLR family pyrin domain containing 3 (NLRP3) inflammasome-mediated pyroptosis in the pathogenesis of Parkinson's disease (PD). Baohuoside I, a natural flavonoid extracted from Herba Epimedii, has been shown to possess anti-inflammatory effects, but its potential neuroprotective effects and mechanism against PD have not been documented. STUDY DESIGN AND METHODS: The anti-inflammatory effects of Baohuoside I were evaluated by LPS-induced BV2 cells or primary microglia isolated from wide type or G protein-coupled estrogen receptor (GPER) gene knockout mice. The underlying mechanism related to GPER-mediated NLRP3 inflammasome inhibition was further explored using LPS-induced GPER+/+ or GPER-/- mouse models of PD. The neuroprotective effects of Baohuoside I were detected through western blot analysis, real-time PCR, molecular docking, mouse behavioral tests, immunofluorescence, and immunohistochemistry. RESULTS: Baohuoside I significantly alleviated LPS-induced neuroinflammation by inhibiting the activation of NF-κB signal and the increase of pyroptosis levels as evidenced by the downregulated expression of pyroptosis-related proteins (NLRP3, ASC, pro-Caspase-1, IL-1ß) in microglia cells. Intragastric administration of Baohuoside I protected against LPS-induced motor dysfunction and loss of dopaminergic neurons, reduced pro-inflammatory cytokines expressions, and inhibited microglial (Iba-1) and astrocyte (GFAP) activation in the nigrostriatal pathway in LPS-induced mouse model of PD. Pretreatment with GPER antagonist G15 in microglia cells or GPER gene deletion in mice significantly blocked the inhibitory effects of Baohuoside I on LPS-induced neuroinflammation and activation of the NLRP3/ASC/Caspase-1 pathway. Molecular docking further indicated that Baohuoside I might bind to GPER directly with a binding energy of -10.4 kcal/mol. CONCLUSION: Baohuoside I provides neuroprotective effects against PD by inhibiting the activation of the NF-κB signal and NLRP3/ASC/Caspase-1 pathway. The molecular target for its anti-inflammatory effects is proved to be GPER in the PD mouse model. Baohuoside I may be a valuable anti-neuroinflammatory agent and a drug with well-defined target for the treatment of PD.

G protein-coupled estrogen receptor 1 ameliorates nonalcoholic steatohepatitis through targeting AMPK-dependent signaling.

Nonalcoholic fatty liver disease (NAFLD), especially nonalcoholic steatohepatitis (NASH), has emerged as a prevalent cause of liver cirrhosis and hepatocellular carcinoma, posing severe public health challenges worldwide. The incidence of NASH is highly correlated with an increased prevalence of obesity, insulin resistance, diabetes, and other metabolic diseases. Currently, no approved drugs specifically targeted for the therapies of NASH partially due to the unclear pathophysiological mechanisms. G protein-coupled estrogen receptor 1 (GPER1) is a membrane estrogen receptor involved in the development of metabolic diseases such as obesity and diabetes. However, the function of GPER1 in NAFLD/NASH progression remains unknown. Here, we show that GPER1 exerts a beneficial role in insulin resistance, hepatic lipid accumulation, oxidative stress, or inflammation in vivo and in vitro. In particular, we observed that the lipid accumulation, inflammatory response, fibrosis, or insulin resistance in mouse NAFLD/NASH models were exacerbated by hepatocyte-specific GPER1 knockout but obviously mitigated by hepatic GPER1 activation in female and male mice. Mechanistically, hepatic GPER1 activates AMP-activated protein kinase signaling by inducing cyclic AMP release, thereby exerting its protective effect. These data suggest that GPER1 may be a promising therapeutic target for NASH.

Activation of GPER-1 Attenuates Traumatic Brain Injury-Induced Neurological Impairments in Mice.

This study aimed to investigate the effects of G1-activated G protein-coupled estrogen receptor 1 (GPER1) on neurological impairments and neuroinflammation in traumatic brain injury (TBI) mice. The controlled cortical impingement (CCI) method was used to establish the TBI model. The mice were subjected to ovariectomy (OVX) for two weeks prior to modeling. GPER1 agonist G1 was administered by intracerebroventricular injection. Brain tissue water content was detected by wet/dry method, and blood-brain barrier damage was detected by Evans blue extravasation. The neurological impairments in mice were evaluated by open field test, Y-maze test, nest-building test, object location memory test and novel object recognition test. Ionized calcium-binding adapter molecule 1 (Iba1) staining was used to indicate the activation of microglia. Expression of M1/M2-type microglia markers and inflammatory factors were evaluated by ELISA and qRT-PCR. The G1 administration significantly reduced cerebral edema and Evans blue extravasation at injury ipsilateral cortex and basal ganglia in TBI mice. Activation of GPER1 by G1 improved the anxiety behavior and the cognitive dysfunction of mice induced by TBI. G1 administration significantly decreased Iba1-positive staining cells and the mRNA levels of CD86, macrophage cationic peptide 1 (Mcp-1), nitric oxide synthase 2 (Nos2), interleukin 1 beta (IL-1ß), and macrophage inflammatory protein-2 (MIP-2), while increased the mRNA levels of interleukin 10 (IL-10), arginase1 (Arg-1) and CD206. Activation of GPER1 through G1 administration has the potential to ameliorate cognitive dysfunction induced by TBI in mice. It may also inhibit the activation of M1 microglia in cortical tissue resulting from TBI, while promoting the activation of M2 microglia and contributing to the regulation of inflammatory responses.

G Protein-Coupled Estrogen Receptor (GPER) and ERs Are Modulated in the Testis-Epididymal Complex in the Normal and Cryptorchid Dog.

There is growing evidence by the literature that the unbalance between androgens and estrogens is a relevant condition associated with a common canine reproductive disorder known as cryptorchidism. The role of estrogens in regulating testicular cell function and reproductive events is supposedly due to the wide expression of two nuclear estrogen receptors (ERs), ER-alpha and ER-beta and a trans-membrane G protein-coupled estrogen receptor (GPER) in the testis. In this study, immunohistochemistry, Western blotting and qRT-PCR were used to assess the distribution and expression of GPER in the testis-epididymal complex in the normal and cryptorchid dog. ER-alpha and ER-beta were also evaluated to better characterize the relative abundances of all three receptors. In addition, in these tissues, the expression level of two proteins as SOD1 and Nrf2 normally associated with oxidative stress was investigated to evaluate a possible relationship with ERs. Our data revealed changes in the distribution and expression of the GPER between the normal and cryptorchid dog. In particular, dogs affected by cryptorchidism showed an upregulation of GPER at level of the examined reproductive tract. Also considering the obtained result of a modulation of SOD1 and Nrf2 expression, we could hypothesize the involvement of GPER in the cryptorchid condition. Further studies are, however, necessary to characterize the role of GPER and its specific signaling mechanisms.

Role of G-protein-coupled estrogen receptor in the pathogenesis of chronic asthma.

BACKGROUND AND AIM: G protein-coupled estrogen receptor (GPER) is an estrogen receptor located on the plasma membrane. We previously reported that the administration of G-1, a GPER-specific agonist, suppressed development of acute ovalbumin (OVA)-induced asthma in a mouse model. Herein, we evaluate the involvement of GPER in a mouse model of chronic OVA asthma. METHODS: G-1 or saline was administered subcutaneously to BALB/c mice with chronic OVA asthma, and pathological and immunological evaluation was performed. In addition, Foxp3-expressing CD4-positive T-cells in the spleen and ILC2 in the lungs were measured using flow cytometry. RESULTS: We observed a significant decrease in the number of inflammatory cells in the bronchoalveolar lavage fluid (BALF) in the G-1 treated group. In the airways, inflammatory cell accumulation, Th2 cytokines (IL-4, IL-5, IL-13, and eotaxin) and epithelial cytokine TSLP were suppressed, while in the BALF, anti-inflammatory cytokines (IL-10 and TGF-ß) were increased. Furthermore, in splenic mononuclear cells, Foxp3-expressing CD4-positive T-cells were increased in the G-1 group, whereas treatment with G-1 did not change the percentage of ILC2 in the lungs. CONCLUSION: G-1 administration suppressed allergic airway inflammation in mice with chronic OVA asthma. GPER may be a potential therapeutic target for chronic allergic asthma.

GPER/PKA-Dependent Enhancement of Hormone-Sensitive Lipase Phosphorylation in 3T3-L1 Adipocytes by Piceatannol.

We previously reported that piceatannol (PIC) had an anti-obesity effect only in ovariectomized (OVX) postmenopausal obesity mice. PIC was found to induce the phosphorylation of hormone-sensitive lipase (pHSL) in OVX mice. To elucidate the mechanism by which PIC activates HSL, we investigated the effect of PIC using 3T3-L1 adipocytes. PIC induced HSL phosphorylation at Ser563 in 3T3-L1 cells, as in vivo experiments showed. pHSL (Ser563) is believed to be activated through the ß-adrenergic receptor (ß-AR) and protein kinase A (PKA) pathways; however, the addition of a selective inhibitor of ß-AR did not inhibit the effect of PIC. The addition of a PKA inhibitor with PIC blocked pHSL (Ser563), suggesting that the effects are mediated by PKA in a different pathway than ß-AR. The addition of G15, a selective inhibitor of the G protein-coupled estrogen receptor (GPER), reduced the activation of HSL by PIC. Furthermore, PIC inhibited insulin signaling and did not induce pHSL (Ser565), which represents its inactive form. These results suggest that PIC acts as a phytoestrogen and phosphorylates HSL through a novel pathway that activates GPER and its downstream PKA, which may be one of the inhibitory actions of PIC on fat accumulation in estrogen deficiency.