G protein-coupled estrogen receptor promotes acrosome reaction via regulation of Ca2+ signaling in mouse sperm†.

G protein-coupled estrogen receptor (GPER), a seven-transmembrane G protein-coupled receptor, mediates the rapid pre-genomic signaling actions of estrogen and derivatives thereof. The expression of GPER is extensive in mammal male reproductive system. However, the functional role of GPER in mouse sperm has not yet been well recognized. This study revealed that GPER was expressed at the acrosome and the mid-flagellum of the mouse sperm. The endogenous GPER ligand 17ß-estradiol and the selective GPER agonist G1 increased intracellular Ca2+ concentration ([Ca2+]i) in mouse sperm, which could be abolished by G15, an antagonist of GPER. In addition, the G1-stimulated Ca2+ response was attenuated by interference with the phospholipase C (PLC) signaling pathways or by blocking the cation channel of sperm (CatSper). Chlortetracycline staining assay showed that the activation of GPER increased the incidence of acrosome-reacted sperm. Conclusively, GPER was located at the acrosome and mid-flagellum of the mouse sperm. Activation of GPER triggered the elevation of [Ca2+]i through PLC-dependent Ca2+ mobilization and CatSper-mediated Ca2+ influx, which promoted the acrosome reaction of mouse sperm.

Role of GPR30 in estrogen-induced prostate epithelial apoptosis and benign prostatic hyperplasia.

Several studies have implicated estrogen and the estrogen receptor (ER) in the pathogenesis of benign prostatic hyperplasia (BPH); however, the mechanism underlying this effect remains elusive. In the present study, we demonstrated that estrogen (17ß-estradiol, or E2)-induced activation of the G protein-coupled receptor 30 (GPR30) triggered Ca2+ release from the endoplasmic reticulum, increased the mitochondrial Ca2+ concentration, and thus induced prostate epithelial cell (PEC) apoptosis. Both E2 and the GPR30-specific agonist G1 induced a transient intracellular Ca2+ release in PECs via the phospholipase C (PLC)-inositol 1, 4, 5-triphosphate (IP3) pathway, and this was abolished by treatment with the GPR30 antagonist G15. The release of cytochrome c and activation of caspase-3 in response to GPR30 activation were observed. Data generated from the analysis of animal models and human clinical samples indicate that treatment with the GPR30 agonist relieves testosterone propionate (TP)-induced prostatic epithelial hyperplasia, and that the abundance of GPR30 is negatively associated with prostate volume. On the basis of these results, we propose a novel regulatory mechanism whereby estrogen induces the apoptosis of PECs via GPR30 activation. Inhibition of this activation is predicted to lead to abnormal PEC accumulation, and to thereby contribute to BPH pathogenesis.

Activation of ß-adrenergic receptors during sexual arousal facilitates vaginal lubrication by regulating vaginal epithelial Cl(-) secretion.

INTRODUCTION: Vaginal lubrication, an indicator of sexual arousal and tissue health, increases significantly during genital sexual arousal. Adrenergic alpha-receptors (AR) are an important regulator of genital physiological responses involved in mediating vascular and nonvascular smooth muscle contractility; the role of ß-AR in sexual arousal, however, has not yet been investigated. AIM: The goal of this study was to reveal the functional role of ß-AR in modulating vaginal lubrication during sexual arousal and the mechanisms underlying the process. METHODS: The effects of adrenaline on vaginal epithelial ion transport, intracellular cyclic adenosine monophosphate (cAMP) content ([cAMP]i ), and vaginal lubrication were investigated using short-circuit current (ISC ) of rat vaginas incubated in vitro, enzyme-linked immunosorbent assay (ELISA), and measurement of vaginal lubrication in vivo, respectively. The expressions of ß-AR in vaginal epithelium were analyzed by reverse transcription-polymerase chain reaction, western blot, and immunofluorescence. MAIN OUTCOME MEASURES: Changes of ISC responses; mRNA, protein expressions and localization of ß-AR; [cAMP]i ; vaginal lubrication. RESULTS: Serosal application of adrenaline induced an increase of ISC across rat vaginal epithelium that blocked by propranolol, a ß-AR antagonist, rather than phentolamine, an α-AR antagonist. ß1/2-AR were both present in rat and human vaginal epithelial cells. Removing Cl(-) or application of CFTR(inh) -172, an inhibitor of cystic fibrosis transmembrane conductance regulator (CFTR), abolished adrenaline-induced ISC responses. The elevated levels of [cAMP]i induced by adrenaline were prevented by the pretreatment with propranolol. Vaginal lubrication measured in vivo showed that adrenaline or pelvic nerve stimulation caused a marked increase in vaginal lubrication, whereas pretreatment with propranolol or CFTR(inh) -172 reduced the effect. CONCLUSIONS: Activation of epithelial ß-AR facilitates vaginal lubrication during sexual arousal by stimulating vaginal epithelial Cl(-) secretion in a cAMP-dependent pathway. Thus, vaginal epithelial ß-AR might be another regulator of vaginal sexual arousal responses.

Efficacy of topical versus oral 5-aminosalicylate for treatment of 2,4,6-trinitrobenzene sulfonic acid-induced ulcerative colitis in rats.

5-aminosalicylic acid (5-ASA) is drug of choice for the treatment of ulcerative colitis (UC). In this study, the efficacy of topical versus oral 5-ASA for the treatment of UC was examined as well as the action mechanism of this medication. A flexible tube was inserted into the rat cecum to establish a topical administration model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced UC. A total of 60 rats were divided into sham operation group (receiving an enema of 0.9% saline solution instead of the TNBS solution via the tube), model group, topical 5-ASA group, oral Etiasa group (a release agent of mesalazine used as positive control) and oral 5-ASA group (n=12 each). Different treatments were administered 1 day after UC induction. The normal saline (2 mL) was instilled twice a day through the tube in the sham operation group and model group. 5-ASA was given via the tube in the topical 5-ASA group (7.5 g/L, twice per day, 100 mg/kg), and rats in the oral Etiasa group and oral 5-ASA group intragastrically received Etiasa (7.5 g/L, twice per day, 100 mg/kg) and 5-ASA (7.5 g/L, twice per day, 100 mg/kg), respectively. The body weight was recorded every day. After 7 days of treatment, blood samples were drawn from the heart to harvest the sera. Colonic tissues were separated and prepared for pathological and related molecular biological examinations. The concentrations of 5-ASA were detected at different time points in the colonic tissues, feces and sera in different groups by using the high pressure liquid chromatography (HPLC). The results showed that the symptoms of acute UC, including bloody diarrhea and weight loss, were significantly improved in topical 5-ASA-treated rats. The colonic mucosal damage, both macroscopical and histological, was significantly relieved and the myeloperoxidase activity was markedly decreased in rats topically treated with 5-ASA compared with those treated with oral 5-ASA or Etiasa. The mRNA and protein expression of IL-1ß, IL-6, and TNF-α was down-regulated in the colonic tissue of rats topically treated with 5-ASA, significantly lower than those from rats treated with oral 5-ASA or Etiasa. The concentrations of 5-ASA in the colonic tissue were significantly higher in the topical 5-ASA group than in the oral 5-ASA and oral Etiasa groups. It was concluded that the topical administration of 5-ASA can effectively increase the concentration of 5-ASA in the colonic tissue, decrease the expression of proinflammatory cytokines, alleviate the colonic pathological damage and improve the symptoms of TNBS-induced acute UC in rats.

Cellular Mechanism Underlying Hydrogen Sulfide Mediated Epithelial K+ Secretion in Rat Epididymis.

As a novel gasotransmitter, hydrogen sulfide (H2S) elicits various physiological actions including smooth muscle relaxation and promotion of transepithelial ion transport. However, the pro-secretory function of H2S in the male reproductive system remains largely unclear. The aim of this study is to elucidate the possible roles of H2S in modulating rat epididymal intraluminal ionic microenvironment essential for sperm storage. The results revealed that endogenous H2S-generating enzymes cystathionine ß-synthetase (CBS) and cystathionine γ-lyase (CSE) were both expressed in rat epididymis. CBS located predominantly in epithelial cells whilst CSE expressed primarily in smooth muscle cells. The relative expression level of CBS and CSE escalated from caput to cauda regions of epididymis, which was paralleled to the progressively increasing production of endogenous H2S. The effect of H2S on epididymal epithelial ion transportation was investigated using short-circuit current (I SC), measurement of intracellular ion concentration and in vivo rat epididymal microperfusion. Our data showed that H2S induced transepithelial K+ secretion via adenosine triphosphate-sensitive K+ (KATP) channel and large conductance Ca2+-activated K+ (BKCa) channel. Transient receptor potential vanilloid 4 (TRPV4) channel-mediated Ca2+ influx was implicated in the activation of BKCa channel. In vivo studies further demonstrated that H2S promoted K+ secretion in rat epididymal epithelium. Inhibition of endogenous H2S synthesis caused a significant decrease in K+ concentration of cauda epididymal intraluminal fluid. Moreover, our data demonstrated that high extracellular K+ concentration actively depressed the motility of cauda epididymal sperm in a pH-independent manner. Collectively, the present study demonstrated that H2S was vital to the formation of high K+ concentration in epididymal intraluminal fluid by promoting the transepithelial K+ secretion, which might contribute to the maintenance of the cauda epididymal sperm in quiescent dormant state before ejaculation.

miR-124 modulates gefitinib resistance through SNAI2 and STAT3 in non-small cell lung cancer.

Gefitinib is used as a first-line treatment for advanced non-small cell lung cancer (NSCLC). Unfortunately, most NSCLC patients inevitably develop gefitinib resistance during treatment. In addition to EGFR mutation status, the mechanisms involved are largely unknown. In this study, we showed that miR-124, a tumor suppressor, was significantly down-regulated in gefitinib-resistant NSCLC patients and cell lines compared with gefitinib-sensitive patients and cell lines. In addition, the miR-124 depletion induced gefitinib resistance, and miR-124 overexpression sensitized gefitinib-resistant cells to gefitinib. Mechanistic analysis revealed that miR-124 decreased SNAI2 and STAT3 expression by directly targeting their 3'UTRs and that knocking down SNAI2 or STAT3 partly reversed the gefitinib resistance induced by miR-124 depletion. Our data demonstrate that the miR-124 plays a new critical role in acquired resistance to gefitinib and that the manipulation of miR-124 might provide a therapeutic strategy for reversing acquired gefitinib resistance.