Run-Ju Zhang

Activation of the epithelial Na + channel triggers prostaglandin E 2 release and production required for embryo implantation

Embryo implantation remains a poorly understood process. We demonstrate here that activation of the epithelial Na+ channel (ENaC) in mouse endometrial epithelial cells by an embryo-released serine protease, trypsin, triggers Ca2+ influx that leads to prostaglandin E2 (PGE2) release, phosphorylation of the transcription factor CREB and upregulation of cyclooxygenase 2, the enzyme required for prostaglandin production and implantation. We detected maximum ENaC activation, as indicated by ENaC cleavage, at the time of implantation in mice. Blocking or knocking down uterine ENaC in mice resulted in implantation failure. Furthermore, we found that uterine ENaC expression before in vitro fertilization (IVF) treatment is markedly lower in women with implantation failure as compared to those with successful pregnancy. These results indicate a previously undefined role of ENaC in regulating the PGE2 production and release required for embryo implantation, defects that may be a cause of miscarriage and low success rates in IVF.

Overweight and obesity negatively affect the outcomes of ovarian stimulation and in vitro fertilisation: a cohort study of 2628 Chinese women

Objective. To explore the effects of overweight and obesity on the outcomes of in vitro fertilisation (IVF) in Chinese infertile patients. Study design. A retrospective cohort study was carried out in 2222 normal weight (18.5 ≤ BMI < 25), 379 overweight (25 ≤ BMI < 30) and 27 obese (BMI ≥ 30) women who underwent their first IVF cycles between 2002 and 2008. Cycle characteristics and IVF outcomes were analysed. Results. Obese women required significantly higher dose of rFSH (3272 IU vs. 2587 IU, p < 0.001) and days of stimulation (11.89 ± 4.57 vs. 10.42 ± 2.03, p < 0.001), but exhibited less oocytes retrieved and significantly lower fertilisation rate (54.1% vs. 61.1%, p < 0.001) than normal weight women. Compared with normal weight women, overweight women displayed significantly less oocytes retrieved (12.98 ± 6.91 vs. 14.49 ± 7.96, p < 0.001), lower fertilisation rate (60.8 ± 23.3 vs. 61.1 ± 23.0, p < 0.001), less cleavaged embryos (7.55 ± 4.86 vs. 8.67 ± 5.90, p < 0.001), less high-grade embryos (4.65 ± 3.96 vs. 5.59 ± 4.81, p < 0.001) and cryopreserved embryos (4.44 ± 4.55 vs. 5.49 ± 5.55, p < 0.001). All parameters of pregnancy outcomes, including pregnancy rate, miscarriage rate and live birth rate, were comparable among three groups. Conclusions. Overweight and obesity are related with impared ovarian response, and negatively affect the outcomes of IVF.

Identification of Estrogen Response Element in the Aquaporin-2 Gene That Mediates Estrogen-Induced Cell Migration and Invasion in Human Endometrial Carcinoma

BACKGROUND Accumulating evidence suggests that aquaporins (AQP) can facilitate cell migration, invasion, and proliferation in tumor development in addition to water transport. OBJECTIVE The aim of this study was to examine AQP2 expression in the endometrial tissues from patients with endometrial carcinoma (EC) and determine the roles and mechanisms of AQP2 in estrogen-related cell migration, invasion, adhesion, and proliferation of Ishikawa (IK) cells. APPROACH AQP2 expression levels were measured in human endometrial cells and estradiol (E(2))-treated IK cells, and the estrogen-response element was identified. After blocking down and up-regulating the endogenous expression of AQP2 in IK cells, cell morphology, capacity for invasion, migration and adhesion, and expression markers of membrane/cytoskeleton were analyzed. RESULTS AQP2 was expressed in endometrial tissues from patients with EC and endometriosis, both of which are estrogen-dependent diseases. In IK cells, E(2) dose-dependently increased AQP2 expression, which was blocked by the estrogen receptor inhibitor ICI182780. An estrogen-response element was identified in the AQP2 promoter. E(2) significantly increased the migration, invasion, adhesion, and proliferation of IK cells. AQP2 knockdown attenuated E(2)-enhanced migration, invasion, and adhesion. AQP2 knockdown reduced not only the E(2)-enhanced expression of F-actin and annexin-2 but also the E(2)-induced alteration of cell morphology. Moreover, higher expression levels of F-actin and annexin-2 were detected in the endometrial tissues from patients with EC. CONCLUSIONS AQP2 mediates E(2)-enhanced migration, invasion, and adhesion through alteration of F-actin and annexin-2 expression and reorganization of F-actin, and inhibition of AQP may be a potential method for antitumor therapy.

Down-Regulation of S100A11, a Calcium-Binding Protein, in Human Endometrium May Cause Reproductive Failure

BACKGROUND Low expression levels of S100A11 proteins were demonstrated in the placental villous tissue of patients with early pregnancy loss, and S100A11 is a Ca2+-binding protein that interprets the calcium fluctuations and elicits various cellular responses. OBJECTIVES The objective of the study was to determine S100A11 expression in human endometrium and its roles in endometrial receptivity and embryo implantation. METHODS S100A11 expression in human endometrium was analyzed using quantitative RT-PCR, Western blot, and immunohistochemical techniques. The effects of S100A11 on embryo implantation were examined using in vivo mouse model, and JAr (a human choriocarcinoma cell line) spheroid attachment assays. The effects of endometrial S100A11 on factors related to endometrial receptivity and immune responses were examined. Using a fluorescence method, we examined the changes in cytosolic Ca2+ and Ca2+ release from intracellular stores in epidermal growth factor (EGF)-treated endometrial cells transfected with or without S100A11 small interfering RNA. RESULTS S100A11 was expressed in human endometrium. S100A11 protein levels were significantly lower in endometrium of women with failed pregnancy than that in women with successful pregnancy outcomes. The knockdown of endometrial S100A11 not only reduced embryo implantation rate in mouse but also had adverse effects on the expression of factors related to endometrial receptivity and immune responses in human endometrial cells. Immunofluorescence analysis showed that S100A11 proteins were mainly localized in endoplasmic reticulum. The EGF up-regulated endometrial S100A11 expression and promoted the Ca2+ uptake and release from Ca2+ stores, which was inhibited by the knockdown of S100A11. CONCLUSIONS Endometrial S100A11 is a crucial intermediator in EGF-stimulated embryo adhesion, endometrium receptivity, and immunotolerance via affecting Ca2+ uptake and release from intracellular Ca2+ stores. Down-regulation of S100A11 may cause reproductive failure.

Aquaporin-1 Plays a Crucial Role in Estrogen-Induced Tubulogenesis of Vascular Endothelial Cells

CONTEXT Aquaporin-1 (AQP1) has been proposed as a mediator of estrogen-induced angiogenesis in human breast cancer and endometrial cancer. Elucidation of the molecular mechanisms governing AQP1-mediated, estrogen-induced angiogenesis may contribute to an improved understanding of tumor development. OBJECTIVE Our objective was to identify the estrogen-response element (ERE) in the promoter of the Aqp1 gene and investigate the effects and mechanisms of AQP1 on estrogen-induced tubulogenesis of vascular endothelial cells. SETTING The study was conducted in a university hospital in eastern China. MAIN OUTCOME MEASURES Immunohistological, real-time PCR and Western blot analyses were used to determine the expression AQP1 mRNA and protein in vascular endothelial cells. Chromatin immunoprecipitation analyses and luciferase reporter assays identified ERE-like motif in the promoter of the Aqp1 gene. RESULTS Expression of AQP1 in blood vessels of human breast and endometrial carcinoma tissues were significantly higher than controls. Estradiol (E2) dose-dependently increased the expression levels of AQP1 mRNA and protein in human umbilical vein endothelial cells (HUVECs). A functional ERE-like motif was identified in the promoter of the Aqp1 gene. AQP1 colocalized with ezrin, a component of the ezrin/radixin/moesin protein complex, and, ezrin colocalized with filamentous actin in HUVECs. Knockdown of AQP1 or ezrin with specific small interfering RNA significantly attenuated the formation of transcytoplasmic filamentous actin stress fibers induced by E2 and inhibited E2-enhanced cell proliferation, migration, invasion, and tubule formation of HUVECs. CONCLUSIONS Estrogen induces AQP1 expression by activating ERE in the promoter of the Aqp1 gene, resulting in tubulogenesis of vascular endothelial cells. These results provide new insights into the molecular mechanisms underpinning the angiogenic effects of estrogen.

Functional expression of large-conductance calcium-activated potassium channels in human endometrium: a novel mechanism involved in endometrial receptivity and embryo implantation.

BACKGROUND Large-conductance calcium-activated potassium channels (BK(Ca) channels) mediate physiological processes in nonexcitable cells. OBJECTIVE The aim of the study was to determine BK(Ca) channel expression in human endometrium and its role in endometrial receptivity and embryo implantation. METHODS BK(Ca) channel expression in human endometrium is described at different phases of the menstrual cycle using quantitative real time-PCR and Western blot techniques. Their effects on embryo implantation were examined using JAr spheroid attachment assays and in vivo mouse model. We examined their effects on endometrial receptivity factors, nuclear factor-κB (NF-κB) activity using quantitative real time-PCR, Western blot, and EMSA analyses. Changes in electrophysiological properties and cytosolic free Ca(2+) were measured in endometrial cells with or without specific BK(Ca) blocker or transfected with BK(Ca) small interfering RNA using patch-clamp and fluorescence analyses, respectively. RESULTS BK(Ca) channels are expressed in human endometrial cells in a phase-related fashion during the menstrual cycle (proliferative, 0.20 ± 0.02, vs. mid-secretory, 0.72 ± 0.07; P < 0.01). Blocking BK(Ca) channel function or knockdown of endogenous BK(Ca) channel expression not only decreased JAr spheroid attachment rate and embryo implantation rate in mice but also significantly reduced the expression levels of endometrial receptive factors, including leukemia inhibitory factor, integrin β3, claudin-4, and DKK-1, in human endometrial cells. Blocking BK(Ca) channels also reduced BK(Ca)-regulated NF-κB activity, cytosolic Ca(2+) concentrations, and membrane potentials in human endometrial cells. CONCLUSIONS These observations demonstrate that BK(Ca) channels: 1) are expressed in endometrial cells; 2) affect embryo implantation by mediating endometrial receptive factors; and 3) alter the activity of NF-κB and homeostasis of Ca(2+) in the human endometrial cells.

Identification of a mutation in GDF9 as a novel cause of diminished ovarian reserve in young women

STUDY QUESTION Do any mutations in growth differentiation factor 9 (GDF9) have a role in diminished ovarian reserve (DOR) in young women? SUMMARY ANSWER The GDF9 p.R146C mutation may be a source of DOR in some young women. WHAT IS KNOWN ALREADY DOR affects 10% of women under 37 years of age and is associated with accelerated expenditure of follicles. GDF9 is an oocyte-secreted factor that plays a critical role in follicular development and female fertility. Several GDF9 variants have been linked to ovarian dysfunction. STUDY DESIGN, SIZE, DURATION This case-control study included 139 women with DOR and 152 controls aged under 37 years. PARTICIPANTS/MATERIALS, SETTING, METHODS All women were recruited in a Chinese tertiary center and underwent DNA sequencing of GDF9 gene. We then determined the molecular and biological properties of mutant GDF9 proteins using protein expression, structural prediction and functional analyses. MAIN RESULTS AND THE ROLE OF CHANCE We identified two mutations in the proregion of GDF9 gene: c.169T > G (p.D57Y) and c.436T > C (p.R146C). The p.R146C mutation was found in three women with DOR but was absent in the control population. This mutation was also associated with significant reductions in GDF9 mature protein secretion in cultured cells. Functional studies with human granulosa cells (GCs) showed that the p.R146C mutation reduced the abilities of GDF9 to stimulate GC proliferation and to activate the Smad2 pathway. Protein structure modeling predicted that p.R146C disrupted an α-helix in GDF9 protein. In contrast with p.R146C, the p.D57Y mutation, found in both the DOR and control groups (6 versus 2), had no obvious deleterious effects. LIMITATIONS, REASONS FOR CAUTION Larger studies in varying populations may validate the role of GDF9 mutation in young women with DOR. WIDER IMPLICATIONS OF THE FINDINGS These results may provide new insights into the pathophysiological mechanisms of early-onset DOR.

Auricular Acupressure Reduces Anxiety Levels and Improves Outcomes of in Vitro Fertilization: A Prospective, Randomized and Controlled Study

The study was to explore whether auricular acupressure (AA) can relieve anxiety during the period from trans-vaginal oocyte retrieval to the embryo transfer in IVF treatment and whether AA can improve the outcomes of IVF. 305 infertile patients with tubal blockage who were referred for IVF were included. The women were randomized into a control group with 102 cases, a Sham-AA group with 102 cases and an AA group with 101 cases. The anxiety levels were rated with Spielbergers State Trait Anxiety Inventory and the Amsterdam Preoperative Anxiety and Information Scale. Data of clinical pregnancy rate (CPR), implantation rate (IR) and live birth rate (LBR) were obtained. The levels of neuropeptide Y (NPY) and transforming growth factor alpha (TGF-alpha) in the follicular fluids were detected with ELISA. After treatment, in AA group, the levels of state anxiety, preoperative anxiety and need-for-information were significantly lower, whereas CPR, IR, LBR and NPY levels in the follicular fluids were markedly higher than Sham-AA group and control group. We concluded that AA could help to reduce anxiety levels associated with IVF and improves the outcomes of IVF partly through increasing the levels of NPY in the follicular fluids.

Small-conductance calcium-activated K+ channels 3 (SK3) regulate blastocyst hatching by control of intracellular calcium concentration

BACKGROUND The present study was designed to investigate the expression of small-conductance calcium-activated K(+) channels 3 (SK3) in preimplantation embryos and to explore their role in the underlying mechanism of blastocyst hatching. METHODS Human preimplantation embryos were donated by patients who achieved successful pregnancy with in vitro fertilization. Mouse preimplantation embryos in different stages were collected and cultured with or without siRNA cell injection. The expression of SK3 was examined by RT-PCR, quantitative real-time PCR, western blot and immunofluorescence. Functional expression of SK3 was investigated using the patch-clamp technique. [Ca(2+)]i was measured by fluorescent imaging. Embryos were cultured in vitro to investigate the effect of SK3 knockdown or apamin, an SK3 inhibitor, on blastocyst hatching and F-actin formation. RESULTS In human blastocysts, the level of SK3 expression was significantly lower in blastocysts that failed to hatch than in blastocysts that hatched successfully. In mouse embryos, SK3 mRNA and protein were not found in zygotes, but were detected from the 2-cell stage onward, with the highest levels observed in blastocysts. SK3 was predominately located in the trophectoderm cell membrane of expanded blastocysts. SK3 knockdown in trophectoderm cells not only suppressed the SK3 current, but also reduced [Ca(2+)]i elevation and membrane potential hyperpolarization induced by thapsigargin. Although the formation of expanded blastocysts was not affected, blastocyst hatching and F-actin formation were significantly inhibited after SK3 knockdown in trophectoderm cells. CONCLUSIONS SK3-mediated [Ca(2+)]i elevation and membrane potential hyperpolarization in trophectoderm cells are important for blastocyst hatching, and defects in SK3 expression may contribute to infertility.

A new model for embryo implantation: coculture of blastocysts and Ishikawa cells

Objective: To explore and develop a new in vitro implantation model that reflects the main process of embryo attachment and invasion. Study design: One of the limitations in human embryo implantation research is lack of an available in vitro model that faithfully replicates human embryo–uterine interactions. In the present study, we examined the attachment and invasiveness of blastocysts from mice in Ishikawa cell (IK), a human endometrial cell, to clarify whether this new model is suitable to study implantation of embryos. We used IK and placed it in contact with blastocysts to initiate coculture experiments using a specifically designed medium. The culture medium was composed of Ham F-12/Dulbecco’s modified Eagle medium (1:1), 30% fetal calf serum, 63.5 nmol/L progesterone, 7.14 nmol/L estradiol-17β, 100 mg/ml of insulin, and 20 ng/ml epidermal growth factor. The culture for 24 h clearly demonstrated that embryos were capable of attachment to the IK and displayed partial invasion. Results: Our results showed that embryos attached to the IK and displayed partial invasion after coculture of blastocysts with IK for 48 h. Conclusions: The model is capable of demonstrating the procedure of attachment and invasion of embryo into the endometrial cells and has promises to be used in studies related to early embryo implantation in human endometrium.