Identification of TRIM22 as a progesterone-responsive gene in Ishikawa endometrial cancer cells

Progesterone plays important roles in implantation and maintains pregnancy. It antagonizes estrogen-mediated cell proliferation and promotes differentiation in the uterus. The action of progesterone is mediated by specific receptors, namely, the progesterone receptors (PRs). We generated two Ishikawa cell clones stably expressing PR isoform A (PR-A) and identified progesterone-responsive genes using cDNA microarray analysis. Fifteen genes were identified as progesterone-responsive gene candidates by microarray analysis and their progesterone-responsiveness was shown by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis. Out of these 15 genes, we focused on TRIM22. A database search revealed a progesterone response element (PRE) located from the -25 to -11 bp region upstream of TRIM22 exon 1. This PRE had a 1-bp mismatch in the consensus PRE sequence. A chromatin immunoprecipitation assay revealed that the interaction of PR with the TRIM22 PRE region increased in a hormone-dependent manner. The progesterone-dependent enhancer activity of TRIM22 PRE was demonstrated using a luciferase assay. Based on these results, we propose that TRIM22 is a direct target gene of PR and that it can mediate progesterone actions in uterine cells.

Expression and regulation of transient receptor potential cation channel, subfamily M, member 2 (TRPM2) in human endometrium

To identify estrogen-responsive genes, we previously isolated estrogen receptor (ER)-binding DNA fragments from human genomic DNA using a recombinant ER protein. Six DNA fragments, each including a perfect palindromic estrogen response element (ERE), were obtained. The nucleotide sequence of one of the six fragments (E1 fragment) showed that the ERE of the E1 fragment is located in the 3'-untranslated region (UTR) of transient receptor potential cation channel, subfamily M, member 2 (TRPM2). Here, we confirmed the estrogen-dependent enhancer activity of the ERE of the E1 fragment by chloramphenicol acetyltransferase assay. TRPM2 mRNA expression was investigated in human endometrium, cultured human endometrial stromal cells (ESCs), and cultured human endometrial epithelial cells (EECs) using RT-PCR. Quantitative RT-PCR revealed that TRPM2 mRNA expression in ESCs increased after 17β-estradiol (E2) treatment. This study demonstrated for the first time that TRPM2 is an estrogen-responsive gene expressed in human endometrial cells.

The progesterone-responsive gene 14-3-3τ enhances the transcriptional activity of progesterone receptor in uterine cells

Members of the 14-3-3 family are intracellular dimeric phosphoserine-binding proteins that can associate with and modulate the activities of many proteins. In our efforts to isolate the genes regulated by progesterone (P(4)) using suppressive subtractive hybridization, we previously found that 14-3-3τ is one of the genes upregulated by P(4). In this study, we demonstrated by quantitative RT-PCR (qRT-PCR), western blot analyses, and immunohistochemistry that 14-3-3τ mRNA and protein levels were increased in the rat uterus after P(4) treatment. Furthermore, qRT-PCR indicated that P(4) increased 14-3-3τ mRNA levels in human endometrial epithelial cells and endometrial stromal cells (ESCs). Western blot and qRT-PCR analyses revealed that in vitro decidualization using cAMP and medroxyprogesterone 17-acetate increased levels of 14-3-3τ mRNA and protein in ESCs. We have shown by qRT-PCR and western blot analyses that P(4) increased the mRNA and protein levels of 14-3-3τ in Ishikawa cells that stably express P(4) receptor-B (PR-B). Immunocytochemistry revealed that 14-3-3τ colocalizes with PR and translocates from the cytoplasm to the nucleus in response to P(4). Moreover, by luciferase reporter assay, we demonstrated that 14-3-3τ enhances the transcriptional activity of PR-B. Taken together, we propose that 14-3-3τ is a P(4)-responsive gene in uterine cells that modulates P(4) signaling.

Expression of retinoic acid-related orphan receptor alpha and its responsive genes in human endometrium regulated by cholesterol sulfate

Cholesterol sulfate (CS) is a major sterol sulfate in human plasma that is detected in the uterine endometrium. CS plays a role in steroidogenesis, cellular membrane stabilization, and regulation of the skin barrier. We previously reported that CS increased in rabbit endometrium during the implantation period. Recently, CS has been reported to be a ligand of retinoic acid receptor-related orphan receptor alpha (RORA). NR1D1 is one of the genes regulated by RORA. In the present study, we investigated the regulation of RORA and NR1D1 by CS in human endometrium. We determined the association-dissociation curves for the interaction of CS with RORA and the kinetic rates by surface plasmon resonance. Immunohistochemical staining and in situ hybridization revealed that RORA and NR1D1 were expressed in human endometrial stromal and epithelial cells. CS treatment significantly induced the mRNA expression of RORA and NR1D1 mRNA in ESCs. The results of a luciferase assay showed that RORA significantly activated the human NR1D1 promoter regardless of CS. Our results suggest that CS regulates the expression of RORA responsive genes in human endometrial cells but not as a ligand for RORA.

Sessile polyps and pedunculated polyps respond differently to oral contraceptives

Endometrial polyp is the lesion frequently found by hysteroscopy. The presence of endometrial polyp is associated with abnormal uterine bleeding and is probably associated with infertility. Until today, clinical guidelines for endometrial polyp remain elusive. The aim of this preliminary study was to estimate whether the shape of endometrial polyps affects the response to the treatment with an oral contraceptive (OC). We performed a retrospective case series study on 50 women diagnosed as endometrial polyps by hysteroscopy and managed by the administration of OC. Hysteroscopy was performed in the follicular phase of the menstrual cycle before medical treatment. Endometrial polyps were classified as pedunculated polyps (n = 25) or sessile polyps (n = 25). After diagnosis, OC was administered for 2-5 months (median 3 months) intermittently: To quantify the regression rate of lesions, the area index of endometrial polyps was assessed. In the study group, when comparing the efficacy of treatment with OC, there was a statistically significant difference in the regression rate between sessile polyps and pedunculated polyps (76% vs. 44%, p = 0.042). We conclude that sessile polyps are more sensitive to OC treatment than pedunculated polyps, implying usefulness of the hysteroscopic classification of the shape of polyps in the management of endometrial polyps.

Decreased pregnancy rate is linked to abnormal uterine peristalsis caused by intramural fibroids

BACKGROUND

The relationship between fibroids and infertility remains an unsolved question, and management of intramural fibroids is controversial. During the implantation phase, uterine peristalsis is dramatically reduced, which is thought to facilitate embryo implantation. Our aims were to evaluate (i) the occurrence and frequency of uterine peristalsis in infertile women with intramural fibroids and (ii) whether the presence of uterine peristalsis decreases the pregnancy rate.

METHODS

Ninety-five infertile patients with uterine fibroids were examined using magnetic resonance imaging (MRI). Inclusion criteria were as follows: (i) presence of intramural fibroids, excluding submucosal type; (ii) no other significant infertility factors (excluding endometriosis); and (iii) regular menstrual cycles, and MRI performed at the time of implantation (luteal phase day 5-9). The frequency of junctional zone movement was evaluated using cine-mode-display MRI. After MRI, patients underwent infertility treatment for up to 4 months, and the pregnancy rate was evaluated prospectively.

RESULTS

Fifty-one patients fulfilled the inclusion criteria, and 29 (57%) and 22 (43%) patients were assigned to the low (0 or 1 time/3 min) or high frequency (≥ 2 times/3 min) uterine peristalsis group, respectively. Endometriosis incidence was the same in both groups. Ten out of the 29 patients (34%) in the low-frequency group achieved pregnancy, compared with none of the 22 patients (0%) in the high-frequency group (P< 0.005). Comparing pregnant and non-pregnant cases, 4 of 10 patients (40%) and 9 of 41 patients (22%), respectively, had endometriosis (not significant).

CONCLUSIONS

A higher frequency of uterine peristalsis during the mid-luteal phase might be one of the causes of infertility associated with intramural-type fibroids.

[Transcervical endoscopic surgery: an update]

Hysteroscopic surgery is considered to be a minimally-invasive procedure. This technique is associated with a shorter hospital stay and a rapid recovery time. At present, with the development of operative technique and instrumention, hysteroscopic surgery is widely performed to disease of endometrial cavity, tubal ostia, or endocervical canal. This procedure needs highly trained technique and can lead to number of associated complications, including uterine perforation and hyponatremia. Falloscpoic tuboplasty (FT) is regarded as a useful and less invasive method for the treatment of tubal occlusion, whereas the operator should have prior experience to avoid the complications such as tubal perforation and damage of instruments. Selective hydrotubation (SHT) with flexible hysterofiberscope is an also effective method for evaluating and managing tubal obstruction. SHT has the advantage of being an easy procedure and can be carried out safely in an outpatient setting.

Case of chronic ectopic pregnancy diagnosed in which the complete shape of the fetus was visible by ultrasonography

Preoperative diagnosis of chronic ectopic pregnancy is often difficult because of the high incidence of negative results on pregnancy tests as a consequence of the very small amount of live villi, subtle symptoms, and the poor specificity of ultrasonographic patterns. A 45-year-old woman was referred to our department for evaluation of a mass 8 cm in diameter with solid parts in the right adnexal area. Transvaginal ultrasonography showed a mass consisting of a cystic part with an irregular thick capsule distinct from the right ovary. In the center of the cystic part, a fetus-like image, 20 mm in length was seen. Preoperative diagnosis was confirmed by the laparoscopy, which revealed a swollen right tube containing a fetus with highly necrotic changes. This case was unique because chronic ectopic pregnancy was detected at an early stage before absorption of the conceptus occurred, which coincidentally is an appropriate time for morphological diagnosis.

Clomiphene citrate elicits estrogen agonistic/antagonistic effects differentially via estrogen receptors alpha and beta

Clomiphene citrate (CC) is known to possess dual actions as an estrogen agonist and an estrogen antagonist. To see how the dual actions of CC are exerted through estrogen receptor alpha (ER alpha) and/or ER beta we developed a cell-based transcription assay system in which 293T cells were transfected with the luciferase reporter plasmid with estrogen responsive element and either human ER alpha or ER beta expression plasmid. CC at lower doses (10(-10) M and 10(-12) M), but not higher doses (10(-6) M and 10(-8) M) elicited estrogenic activity via ER alpha. However, CC at concentrations between 10(-6) M and 10(-12) M did not elicit any estrogenic activity via ER beta. In the presence of 17beta-estradiol (E2), CC behaved either as an agonist or as an antagonist via ER alpha depending on the concentrations of E2, i.e., antagonistic when combined with the higher E2 concentrations, agonistic with the lower E2 concentrations. On the other hand, via ER beta, CC acted as an estrogen antagonist regardless of the concentration of E2 added together. In conclusion, CC acts as an estrogen agonist/antagonist via ER alpha in a coexisting estrogen concentration-dependent way whereas it acts as an estrogen antagonist via ER beta whether or not estrogen is present.

Autoamputated adnexa presents as a peritoneal loose body

We report a case of unilateral adnexal absence with a peritoneal loose body. Laparoscopic findings and medical history suggested that she had adnexal torsion in her childhood followed by its calcification and autoamputation.

Expression and regulation of cholesterol sulfotransferase (SULT2B1b) in human endometrium

OBJECTIVE

To investigate the hormonal regulation of SULT2B1b in human endometrium.

DESIGN

In vitro study with human endometrial tissues and cultured human endometrial cells.

SETTING

University hospital.

PATIENT(S)

Thirty-seven women undergoing hysterectomy for benign disease.

INTERVENTION(S)

Human endometrial tissues were collected for in situ hybridization. Culture medium of human endometrial epithelial cells (EECs) was collected for determination of secretion of cholesterol sulfate (CS). Total RNAs were extracted from human endometrial tissues and cultured cells for real-time reverse transcriptase-polymerase chain reaction (RT-PCR).

MAIN OUTCOME MEASURE(S)

The expression of SULT2B1b mRNA in human endometrial tissues and cultured cells.

RESULT(S)

In situ hybridization studies and real-time RT-PCR showed that the amount of SULT2B1b mRNA in human endometrial tissues was significantly higher during the midluteal phase than during other phases of the menstrual cycle. The secretion of CS from EECs was confirmed using [(35)S]-phosphoadenosine phosphosulfate. The expression of SULT2B1b mRNA was induced by cAMP or P in human endometrial stromal cells (ESCs), whereas it was induced by cAMP or relaxin in EECs. The induction of SULT2B1b mRNA by P or relaxin was abolished by the specific protein kinase A (PKA) inhibitor, Rp-adenosine 3',5' cyclic monophosphothioate (Rp-cAMPS).

CONCLUSION(S)

The expression of SULT2B1b mRNA in ESCs is induced by P and that in EECs is induced by relaxin via the cAMP pathway.

Inhibitory effects of cholesterol sulfate on progesterone production in human granulosa-like tumor cell line, KGN

Cholesterol sulfate (CS) is a component of cell membranes that plays a role in stabilizing the cell membrane. We previously reported that CS increased in the endometrium during implantation, suggesting that CS plays an important role in reproduction. It has been reported that CS regulates progesterone and pregnenolone production in the placenta, adrenal glands and ovary. The regulatory mechanisms of steroid hormone production by CS, however, are still unknown. In the present study, we investigated the effect of CS on the expression of progesterone production-related genes in KGN cells, derived from human granulosa-like tumor. KGN cells were cultured with CS (10 muM) or cholesterol (10 muM) in the presence of 8-bromo-cAMP (1 mM). Progesterone levels in the culture media were measured by enzyme linked fluorescent assay at 24 h after treatment of CS and cAMP. Total RNAs were extracted for quantitative real time RT-PCR with specific primer of StAR protein, P450scc, HSD3B2, ferredoxin and ferredoxin reductase. Whole cell lysates were extracted for western blot analysis with antibody for StAR protein. Progesterone concentration in the culture medium increased to 38-fold by treatment of cAMP. CS significantly reduced progesterone concentration by 30% compared with those of cAMP treatment (p<0.05), while cholesterol did not change the progesterone concentration. CS treatment down-regulated the expression of StAR mRNA and P450scc mRNA was to 54% and 60%, respectively (p<0.05). Western blot analysis revealed that the amount of StAR protein was also reduced by CS treatment. The expression of HSD3B2 mRNA was up-regulated to 3.4-fold by treatment of cAMP. The expression of ferredoxin and ferredoxin reductase mRNA was not affected by CS treatment. These data implied that CS has an inhibitory effect on progesterone production by regulating the expression of StAR and P450scc gene expression.

Expression and regulation of periostin/OSF-2 gene in rat uterus and human endometrium

Periostin/OSF2 is a ligand for alphavbeta3 and alphavbeta5 integrins and activates the Akt/PKB pathway. Recent reports of periostin/OSF2 gene disrupted mice indicate that periostin/OSF-2 plays an important role in implantation. Quantitative RT-PCR revealed that the expression of periostin/OSF-2 mRNA in rat uteri was reduced to approximately 10% at 12 h after 17beta-estradiol (E2) injection, but was not changed after progesterone (P) injection. RT-PCR revealed the expression of periostin/OSF-2 in human endometrium, cultured human endometrial stromal cells (ESCs), and cultured human endometrial epithelial cells. In ESCs, the expression of periostin/OSF-2 mRNA was reduced to approximately 50% at 6 h after E2 treatment. The amount of periostin/OSF2 mRNA in human endometrium significantly increased during mid-proliferative and early secretory phases of menstrual cycle, and decreased during late-proliferative, mid-secretory and late secretory phases. The expression of periostin/OSF2 mRNA significantly decreased in ESCs decidualized by treatment with E2 and P for 7 and 11 days. By immunohistochemistry, the expression of periostin/OSF-2 was strongly detected in endometrial stromal cells during early proliferative, mid-proliferative and early secretory phases, and was strongly detected in endometrial epithelial cells during late secretory phase. This study demonstrated that the expression of periostin/OSF-2 is regulated by ovarian steroid hormones in rat uterus and human endometrium.

Evidence for the expression of alcohol dehydrogenase class I gene in rat uterus and its up-regulation by progesterone

The endometrium is one of the target tissues of the ovarian steroid hormones, estrogen and progesterone. In order to elucidate the mechanism of gene regulation in the endometrium, suppressive subtraction hybridization was performed to isolate the candidate genes controlled by progesterone in rat uterus. Alcohol dehydrogenase (ADH) class I gene was one of the candidate genes. Here we investigated the expression and regulation of ADH class I gene in rat uterus. The mRNA of ADH class I was detected in uterus by RT-PCR using specific primers. Using specific probe for ADH class I, in situ hybridization was performed to investigate localization in rat uterus. Positive signals were detected in the endometrial stromal cells of rat uterus by in situ hybridization and were not detected in endometrial epithelial cells and myometrium in rat uterus. Ovariectomized rats were treated with 17-beta estradiol and progesterone and the uteri of these rats were used for Northern blot analysis and assay of the ADH activity. Northern blot analysis revealed that the expression of ADH class I mRNA in rat uteri was up-regulated approximately two-fold after progesterone treatment, but not estrogen. Likewise, ADH activity was approximately two-fold higher in progesterone-treated rat uteri compared with controls. This study demonstrated that ADH class I gene is progesterone-responsive in the uterus. This implies that progesterone might be involved with retinoic acid synthesis in the uterus, since ADH is the key enzyme for retinoic acid synthesis.

A case of hydrosalpinx associated with the menstrual cycle

OBJECTIVE

To describe a case report of hydrosalpinx that changed dramatically in size during the menstrual cycle.

DESIGN

Case report.

SETTING

University teaching hospital reproductive endocrinology and infertility practice.

PATIENT(S)

A 32-year-old woman with a history of medical and surgical treatments of endometriosis who sought infertility treatment.

INTERVENTION(S)

Transvaginal ultrasonography performed sequentially during menstrual cycles.

MAIN OUTCOME MEASURE(S)

Size of hydrosalpinx-like image.

RESULT(S)

The size of the hydrosalpinx-like image in the left adnexal region varied; it peaked during the ovulatory period and then remarkably diminished in a cyclic manner. Laparoscopy revealed a dense adhesion between the left tubal fimbriated end and the posterior uterine wall, which led to terminal obstruction of the tube.

CONCLUSION(S)

Change in the volume of the hydrosalpinx in this case was speculated to reflect the normal tubal fluid production regulated by ovarian hormones.

High incidence of tubal dysfunction is determined by laparoscopy in cases with positive Chlamydia trachomatis antibody despite negative finding in prior hysterosalpingography

Aim:  Hysterosalpingography (HSG) is one of the most commonly used methods in order to evaluate the condition of fallopian tubes in infertility clinics. In the present paper, we retrospectively compared the findings of HSG and laparoscopy to elucidate the relationship between tubal dysfunction and background factors, such as Chlamydia trachomatis infection, endometriosis and previous surgery. Methods:  We retrospectively reviewed clinical records of 314 patients who were examined by both HSG and laparoscopy between 1996 and 2001 in the Department of Obstetrics and Gynecology, University of Tokyo. Results:  When HSG findings were evaluated in reference to those of laparoscopy, sensitivity and specificity for tubal patency were 0.63 and 0.79, respectively, whereas those for peri-tubal adhesion were 0.65 and 0.61, respectively. We compared the percentage of existence of background factors between the patients who were diagnosed as normal by both HSG and laparoscopy (Group L[+]) and those whose fallopian tubes were observed as patent by HSG, but were not patent by chromopertubation under laparoscopy (Group L[-]). The percentage of patients with positive chlamydial antibodies in Group L(-) (42.9%, 15/35) was significantly higher than that of patients with positive chlamydial antibodies in Group L(+) (22.8%, 44/193, P < 0.05). Conclusions:  These finding suggested that even if HSG showed normally patent tubes in a patient with positive Chlamydia trachomatis antibodies, the possibility of tubal occulusion still remains high and further examination by laparoscopy is recommended. (Reprod Med Biol 2007; 6: 39-43).

A case of giant cystic adenomyosis

We describe a 37-year-old woman with giant cystic adenomyosis who underwent a hysterectomy, providing magnetic resonance imaging and gross and microscopic images.

Differences in serum bisphenol a concentrations in premenopausal normal women and women with endometrial hyperplasia

Exposure to endocrine disrupting chemicals (EDCs) has been raised in relation to its potential for adverse health outcomes. Bisphenol A (BPA) is an estrogenic EDC widely found in plastic products. We determined BPA concentrations in premenopausal women by an enzyme-linked immunosorbent assay and evaluated possible linkage between its contamination levels and endometrial hyperplasia, an estrogen-related disorder of the uterus. It has been implied that higher levels of BPA, which binds to estrogen receptor and plays estrogenic roles may, enhance endometrial hyperplasia. Serum BPA was detectable in all subjects and its concentrations in healthy controls with normal endometrium were 2.5 +/- 1.5 ng/ml (mean +/- SD). BPA levels in patients with simple endometrial hyperplasia with benign nature were 2.9 +/- 2.0 ng/ml and were not significantly different from the controls. Unexpectedly, BPA levels in patients with complex endometrial hyperplasia with malignant potential were 1.4 +/- 0.4 ng/ml and significantly lower compared to both control and simple endometrial hyperplasia groups. In addition, we measured the serum BPA levels in postmenopausal endometrial cancer patient (1.4 +/- 0.5 ng/ml), which were also significantly lower than control and simple endometrial hyperplasia groups. These findings suggest the presence of associations between BPA exposure and complex endometrial hyperplasia and endometrial cancer. The mode of action of BPA may be more complex than expected and the contradictory results may serve as a clue to addressing the mechanisms of linkage between occurrence of estrogen-dependent diseases and endocrine disruption.

Regulation of transcription of the steroidogenic acute regulatory protein (StAR) gene: temporal and spatial changes in transcription factor binding and histone modification

We examined the binding of transcription factors and histone modifications associated with induction of expression of the steroidogenic acute regulatory protein (StAR) gene in MA-10 cells using a quantitative chromatin immunoprecipitation (ChIP) assay. GATA-4, SF-1/Ad4BP, and cyclic AMP response element binding protein binding protein (CBP) bind rapidly to the StAR proximal promoter, but in different patterns following 8-Br-cAMP stimulation. Concomitantly, histone modifications occur in a spatial and temporal sequence including increased association of acetylated histone H3 with the proximal promoter region, increased association of dimethylated lysine 4 histone H3 with exonic sequences, a modification that marks actively transcribed regions, and reduced association of a marker linked to gene silencing (lysine 9 dimethylated histone H3). Our findings demonstrate that transcription factors and coactivators are rapidly associated with the StAR proximal promoter, that the patterns of binding differ which has implications for postulated direct interactions among these factors, and that multiple histone modifications are demonstrable in a spatially- and temporally-specific pattern along the StAR gene. These observations suggest that a combinatorial code of transcription factors including reciprocal changes in histone modifications associated with active transcription and gene silencing control StAR gene expression.

Temporal and spatial changes in transcription factor binding and histone modifications at the steroidogenic acute regulatory protein (stAR) locus associated with stAR transcription

We investigated the binding of transcription factors and histone modifications associated with expression of the steroidogenic acute regulatory protein (StAR) gene in cultured MA-10 Leydig cells and in granulosa cells isolated from mouse periovulatory follicles before and after in vivo human chorionic gonadotropin administration. Quantitative chromatin immunoprecipitation assays were employed to prove association of specific transcription factors (GATA-4, steroidogenic factor 1/adrenal-4 binding protein, CCAAT/enhancer-binding protein beta, cAMP response element binding protein/cAMP response element modulator) and a coactivator (cAMP response element binding protein-binding protein) with the promoter, to define patterns of binding to test hypotheses regarding interactions among these factors, and to correlate changes in histone modification at the StAR locus with transcription. Although each of the transcription factors bound to the StAR proximal promoter, we observed cell-specific binding patterns for individual factors. From these findings we infer that associations among some of the factors can be more complex than can be explained by simple models of stable protein-protein interactions. Histone modifications were also found to exhibit cell-specific, temporal and spatial differences across the StAR locus. In MA-10 cells, these modifications included increased acetylation of histone H3, increased dimethylation of lysine 4 on histone H3 in exonic/intronic sequences (a modification that marks transcriptionally permissive chromatin), and reduced dimethylation of lysine 9 on histone H3 (a modification linked with gene silencing). In mouse granulosa cells, we observed no change in histone H3 or H4 acetylation, but a rapid loss of the dimethyl K9 histone H3 mark. Our findings demonstrate that increased StAR transcription can occur in the context of different patterns of transcription factor binding and histone modification.

Expression of estrogen, progesterone and androgen receptors in the oviduct of developing, cycling and pre-implantation rats

To determine expression and localization of receptors for estrogen (ER), progesterone (PR) and androgen (AR), detailed immunohistochemical evaluations were performed in the Sprague-Dawley rat oviduct during pre- and neonatal development, estrous cycle and pre-implantation period. In addition, real-time RT-PCR studies were conducted to evaluate changes in ERalpha, ERbeta, total PR (PR-A+B), PR-B and AR mRNA expressions. All receptors except for ERbeta were detected in epithelial, and stromal or mesenchymal cells of the fetal and neonatal oviduct, and increased with development. During the estrous cycle and early pregnancy, ERalpha and PR-A+B were expressed in epithelial, stromal and muscle cells throughout the oviduct region, and showed changes in expression predominantly in the isthmus. Only a few epithelial cells in the infundibulum (inf) and ampulla (AMP) showed ERbeta staining. AR was detected in stromal and muscle cells throughout the oviduct region, and in epithelial cells of the inf/AMP. Taken together, ERalpha, PR-A+B and AR were detected in the epithelium of the inf/AMP region, but all of these receptors were expressed in a distinct subset of epithelial cells which were negative for beta-tubulin IV, a ciliated epithelial cell marker. These results contribute to a better understanding of the respective roles of ERs, PRs and AR in the rat oviduct.

START domain proteins and the intracellular trafficking of cholesterol in steroidogenic cells

The intracellular trafficking of cholesterol in steroidogenic cells plays an important role in the regulation of hormone synthesis. Recent evidence indicates that a family of proteins related to the steroidogenic acute regulatory protein (StAR) perform critical functions in moving the sterol substrate to the mitochondrial inner membrane where the first committed step in steroid hormone synthesis occurs. StAR, the prototype of the family, is known to promote the translocation of cholesterol from the outer to the inner mitochondrial membrane. Mutations in StAR cause congenital lipoid adrenal hyperplasia, a cholesterol storage disorder in which synthesis of all gonadal and adrenocortical steroid hormones is severely impaired, and the cholesterol that is not efficiently moved into the mitochondria accumulates in cytoplasmic lipid droplets. The StAR-related lipid transfer (START) domain consists of an approximately 210 amino acid residue sequence that forms a compact alpha/beta structure, a helix-grip fold, with a hydrophobic tunnel that can accommodate a sterol molecule. START domains can bind sterol, facilitate the transfer of cholesterol from sterol-rich unilammelar liposomes to acceptor membranes, and stimulate steroidogenesis when expressed in cells co-expressing the cholesterol side-chain cleavage system or when added to isolated steroidogenic mitochondria. Sixteen human START domain proteins have been identified to date. Of these, StAR and MLN64 consist of one subfamily and newly described proteins named StarD4, StarD5, and StarD6 represent a closely related second subfamily. MLN64 is incorporated into the late endosomal compartment and is involved in the movement of cholesterol acquired from endocytosed LDL out of these vesicles. Expression of a dominant negative form of MLN64 causes accumulation of free cholesterol in lysosomes. The roles of StarD4, StarD5, and StarD6 in sterol movement remain to be determined. These genes have tissue-specific patterns of expression that may predict specialized roles.

A case of estrogen-producing Brenner tumor with a stromal component as a potential source for estrogen

BACKGROUND

Although Brenner tumors with endocrine activities have been reported, the source or mechanisms for hormone production is poorly known at present.

CASE REPORT

A 66-year-old Japanese woman presented with atypical vaginal bleeding. A left ovarian tumor was detected on ultrasonography and CT scanning. Her serum estradiol level was elevated (73.5 pg/ml). We performed total hysterectomy, bilateral salpingo-oophorectomy and partial omentectomy. The ovarian tumor was diagnosed as a benign Brenner tumor associated with simple hyperplasia of the endometrium. Postoperatively, the serum estradiol level decreased. Immunoreactivity of cytochrome P-450 aromatase was detected in stromal cells.

CONCLUSION

Stromal contribution to the secretion of estrogen was shown in this case. Considering the known source of estrogen production being tumor cells in certain cases of Brenner tumor, there seem to be two types of estrogen-producing Brenner tumors depending on the source of estrogen, i.e. tumor cells or stromal cells.

The activity of bisphenol A depends on both the estrogen receptor subtype and the cell type

Bisphenol A (BPA), a monomer of plastic used in consumer products, is abundant in the environment and enters the body by ingestion or adsorption. In order to characterize the estrogenic effect of BPA, we performed luciferase assay on three independent cell lines derived from different tissues transfected with either human ERalpha cDNA or ERbeta cDNA. The estrogenic activities of BPA were detectable in all cell lines via both ERalpha and ERbeta. In 293T cells and Hec-1 cells, the estrogenic activities were significantly decreased when cells expressing ERalpha were incubated with 10(-6) M BPA in the presence of 10(-8) M 17beta-estradiol (E2) while the activities via ERbeta were essentially unchanged in the same conditions. Interestingly, no reduction of estrogenic activity was detected in HOS-TE85 cells via either ERalpha or ERbeta. Our results indicate that BPA only acts as an agonist of estrogen via ERbeta whereas it has dual actions as an agonist and antagonist in some types of cells via ERalpha. Thus, the activity of BPA may depend on the ER subtype and the tissue involved.

Changes in ontogenetic expression of estrogen receptor alpha and not of estrogen receptor beta in the female rat reproductive tract

To evaluate ontogenetic expression and localization of estrogen receptor (ER) alpha and beta in fetal female rat reproductive tract, competitive RT-PCR and immunohistochemistry were performed. Expression levels for Müllerian ERalpha, ERbeta1 and ERbeta2 mRNAs were determined by competitive RT-PCR. ERalpha expression on gestational day (GD) 15 x 5 increased 4 x 4-fold by GD 21 x 5, whereas both ERbeta1 and ERbeta2 gene expression were maintained at lower constant levels compared with ERalpha during development. ER immunolocalization was evaluated within three regions along the Müllerian duct axis; these were proximal, middle and caudal, which differentiate into oviduct, uterus and upper vagina respectively. Nuclear ERalpha was localized predominantly in proximal Müllerian epithelium, and middle and caudal Müllerian mesenchyme on GDs 15 x 5-21 x 5. Staining intensity for ERalpha increased with development in all regions. However, ERbeta immunoreactivity was not detected in any region during prenatal life after separate staining with three different polyclonal anti-rat ERbeta antibodies. These findings provide fundamental information critical for clarifying the species-specific physiological roles of ER subtypes during fetal development and for investigating the tissue-specific mechanisms underlying the prenatal response to estrogen and estrogen receptor agonists.

Demonstration of angiogenin in human endometrium and its enhanced expression in endometrial tissues in the secretory phase and the decidua

Angiogenesis is thought to be crucial for normal physiology of the endometrium, where dynamic vascular remodeling occurs during the menstrual cycle and pregnancy. We investigated the presence of angiogenin, a potent inducer of angiogenesis, and the regulatory mechanisms of its production in the human endometrium. Western blot analysis demonstrated that angiogenin protein expression increased by 3- to 4-fold in the endometrium in the mid and late secretory phases and in early gestation relative to that during the proliferative phase. Quantitative mRNA analysis showed the similar tendency in the expression of angiogenin mRNA in the endometrium, with the highest levels observed in the mid and late secretory phases and early gestation. An immunohistochemical study showed that angiogenin was expressed in both stromal cells and epithelial cells, with indistinguishable intensity between these cells regardless of phases of the menstrual cycle. In support of the Western blot analysis, the intensity of staining appeared to be highest in the mid to late secretory phases relative to other phases. Consistent with these in vivo results, decidualized cultured stromal cells, after treatment with progesterone or progesterone plus E2, exhibited the capacity to secrete significantly increased amounts of angiogenin compared with untreated or E2 alone-treated control group. Both the treatment with (Bu)2cAMP and hypoxic conditions stimulated angiogenin secretion by stromal cells. For isolated epithelial cells, hypoxia stimulated angiogenin secretion, whereas (Bu)2cAMP had no appreciable effect. In summary, we demonstrated the presence of angiogenin in human endometrium and its possible local regulatory factors, such as progesterone, cAMP, and hypoxia. These findings along with its enhanced expression in the endometrium in the secretory phase and in decidual tissues raise the possibility that angiogenin may play a role in establishing pregnancy.

Hyperemesis gravidarum associated with thyrotoxicosis and a past history of an eating disorder

We present a case of severe hyperemesis gravidarum (HG) associated with thyrotoxicosis in a woman with a past history of an eating disorder. She had developed persistent HG from early pregnancy until about at the end of the second trimester with a body loss of 14 kg. Total parenteral nutrition was effective in alleviateing HG. It is suggested that even a past history of an eating disorder could be at risk of developing HG.

Molecular cloning and characterization of mouse EBAG9, homolog of a human cancer associated surface antigen: expression and regulation by estrogen

We previously identified a human estrogen-responsive gene, EBAG9 (ER-binding fragment-associated antigen9) (Watanabe, T. et al., Mol. Cell. Biol. 18, 442-449, 1998). It was later reported as RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) that induced apoptosis and suppressed the growth of several cells such as activated T cells (Nakashima, M. et al., Nat. Med. 5, 938-942, 1999). Here, we have isolated both cDNA and genomic DNA of mouse EBAG9/RCAS1. Mouse EBAG9 gene spans about 30 kb in genomic DNA and consists of 7 exons. Mouse EBAG9 cDNA encodes a protein that contains the transmenbrane segment and coiled-coil domain. An alignment between the predicted mouse and human EBAG9 shows a high degree of homology at the amino acid level (98%). Northern and Western blot analyses demonstrate that EBAG9 is expressed in several tissues including the heart, brain, spleen, liver, kidney, and testis, and also in developing embryo. In the uterus, a target organ for estrogen, the EBAG9 was shown to be upregulated in vivo by 17beta-estradiol. To determine the biological action of mouse EBAG9, NIH3T3 fibroblastic cells were incubated with recombinant EBAG9 protein, resulting in suppression of cell growth. These findings suggest that EBAG9 is an in vivo estrogen-responsive gene that inhibits the cell growth.

Mucinous adenocarcinoma arising in a neovagina using the sigmoid colon thirty years after operation: a case report

BACKGROUND

Because of a relative rarity of the cases with an artificial vagina, the incidence of a case with malignant disease arising in the neovagina is extremely rare. A case of adenocarcinoma arising from a neovagina is presented with a review of the literature.

CASE

A neovagina was constructed using the sigmoid colon at the age of 23 for congenital agenesis of the vagina, Rokitansky-Küster-Hauser syndrome. Subsequently, the patient had regular sexual intercourse for about 20 years. At the age of 53, she came to our outpatient clinic with a complaint of vaginal bleeding, and adenocarcinoma was found at the anterior wall of the neovagina adjoining the introitus. Total resection of the neovagina and adjuvant radiotherapy was performed. The pathological diagnosis was mucinous adenocarcinoma.

CONCLUSIONS

In view of relatively low incidence of mucinous carcinoma arising in the sigmoid colon along with the ectopic localization, this case may have implications for the understanding of pathogenesis of sigmoid colon cancer.

Evidence for the presence of keratinocyte growth factor (KGF) in human ovarian follicles

The presence of keratinocyte growth factor (KGF) in human follicular fluid (FF) was investigated in a total of 145 FFs obtained during oocyte retrieval for in vitro fertilization (IVF) from 29 patients with no apparent endocrine disorders. The concentrations of KGF, estradiol, progesterone, testosterone and human chorionic gonadotropin (hCG) in FF were measured by enzyme-linked immunosorbent assay. FF samples contained relatively higher amounts of KGF (2194+/-87 pg/ml), whereas its concentrations in serum were below assay limit (<31.2 pg/ml). Concentrations of KGF in FF were positively correlated with both progesterone (r=0.311, p<0.0005) and testosterone (r=0.230, p<0.01) concentrations in FF. However, KGF concentrations were not significantly correlated with estradiol and hCG concentrations. KGF in FF was detected as a broad band (26-29 kD) by immunoblotting, the size being reduced by 7kD after N-glycosidase treatment. In an in vitro experiment, KGF suppressed the basal and hCG-stimulated progesterone production by cultured human luteinized granulosa cells. summary, we demonstrated the presence of KGF in human ovarian follicles, suggesting its possible role as a local factor in regulating human ovarian functions.

Stem cell factor (SCF) concentrations in peritoneal fluid of women with or without endometriosis

PROBLEM

In the quest for possible involvement of stem cell factor (SCF), a cytokine known to have multiple effects, in the pathogenesis of endometriosis, we evaluated concentrations of SCF in peritoneal fluid (PF) of women with or without endometriosis.

METHOD OF STUDY

SCF concentrations in PF collected from women undergoing laparoscopy were measured, using a specific enzyme-linked immunosorbent assay (ELISA). Reverse transcription-polymerase chain reaction (RT-PCR) analysis to detect gene expression of c-kit, the receptor for SCF, was performed using the endometriotic tissue and the eutopic endometrium collected during the operation.

RESULTS

SCF concentrations in PF of women with endometriosis were significantly higher compared to women without endometriosis. Looking at SCF concentrations in PF of women with endometriosis stratified by disease stage, women with stage I and II exhibited relatively higher SCF levels in PF, whereas SCF levels in PF with stage III and IV were comparable with those without endometriosis. The expression of mRNA for c-kit was detected in both the endometriotic tissue and the eutopic endometrium.

CONCLUSION

We demonstrated an elevation in SCF levels in PF associated with endometriosis and the presence of its receptor in endometriotic tissues. Given the known pleiotropic properties of SCF, the present results suggest that SCF might play a role in the pathogenesis of endometriosis.

A fetus with Prader-Willi syndrome showing normal diurnal rhythm and abnormal ultradian rhythm on heart rate monitoring

Clinical features of Prader-Willi syndrome in neonates are marked hypotonia with the absence of crying and feeding difficulty so that prenatal diagnosis of Prader-Willi syndrome is strongly hoped in order to provide appropriate medical and psychological care for neonates and their families. However, the clinical picture of Prader-Willi syndrome in utero has not been well described. We report a pregnancy associated with Prader-Willi syndrome manifesting polyhydramnios, large biparietal diameter of the fetus and characteristic fetal heart rate pattern: prolonged inactive periods and diurnal variation of the incidence of heart rate accelerations. These findings may offer a clue to the prenatal diagnosis of Prader-Willi syndrome, although molecular cytogenetics is mandatory for the definite diagnosis.

Estrogen receptor-mediated effects of a xenoestrogen, bisphenol A, on preimplantation mouse embryos

The effects of bisphenol A, a xenoestrogen widely used in industry and dentistry, were studied in early preimplantation mouse embryos. Two-cell mouse embryos were cultured with 100 pM to 100 microM bisphenol A with or without 100 nM tamoxifen and evaluated at 24-h intervals for their development to eight-cell and blastocyst stages. At 72 h, blastocysts were cultured for another 48 h without bisphenol A, and surface areas of trophoblast spread were measured. At 24 h, more embryos exposed to 3 nM bisphenol A than to controls had reached the eight-cell stage. At 48 h, more embryos exposed to 1 nM and 3 nM bisphenol A than to controls had become blastocysts. At 100 microM, bisphenol A decreased frequency of development to blastocysts. Tamoxifen counteracted both stimulatory and inhibitory effects of bisphenol A on blastocyst formation. Although bisphenol A did not alter blastocyst morphology or cell number, early exposure to 100 microM bisphenol A increased subsequent trophoblast areas. These findings suggest that bisphenol A may not only effect early embryonic development via estrogen receptors even at low, environmentally relevant doses, but also exert some late effects on subsequent development of these embryos.

Ontogenetic changes in the expression of estrogen receptor alpha and beta in rat pituitary gland detected by immunohistochemistry

The physiological effects of estrogen on the pituitary, including cellular proliferation and regulation of hormone synthesis, are mediated by the nuclear estrogen receptor (ER). The purpose of this study was to determine ontogenetic expression of two types of ERs (ERalpha and ERbeta) in the pituitary using specific antibodies, monoclonal antibody (1D5) for ERalpha and polyclonal antibody generated against ERbeta. First, we confirmed the detection of 66- and 55-kDa bands for ERalpha and ERbeta, respectively, in the rat pituitary extract by Western blotting. Then immunostaining with these antibodies was performed using fetal and adult Wistar rat tissues, combined with PRL or LHbeta immunohistochemistry. Intense ERbeta signal was detected throughout the pituitary from day 12 of gestation. However, staining for ERalpha only became detectable from day 17 of gestation. In contrast with the fetal period, nuclei stained for ERalpha were widely distributed in the anterior lobe in the adult rat, whereas ERbeta-positive cells were restricted in the anterior lobe. LHbeta, but not PRL, was colocalized in ERbeta-positive cells. Our results indicated that the major population of ER subtypes in the rat pituitary gland has changed around the day of birth and that the expression of ERbeta may be involved in the differentiation of pituitary cell function to synthesize a specific hormone.

An earlier menopause as clinical manifestation of granulosa-cell tumor: a case report

We present a case of a granulosa-cell tumor, which can cause menopause at an earlier than normal age. The hormonal profiles were characterized by undetectable FSH levels associated with an estradiol level compatible with the level seen in perimenopausal women and by a significant increase in the inhibin level.

Expression of Ah receptor and dioxin-related genes in human uterine endometrium in women with or without endometriosis

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been suggested as a possible etiologic factor for endometriosis, a condition in which endometrium-like tissues are present outside the uterus. The prevailing view pertaining to the origin of endometriotic cells is that they are from eutopic endometrial cells which regurgitate through fallopian tubes. In order to get insight into the possible involvement of TCDD in the pathogenesis of endometriosis, we suspected that TCDD may act differently on the endometrium with or without endometriosis. To address this, we examined the presence of messenger RNAs of arylhydrocarbon receptor (AhR), AhR nuclear translocator (Arnt) and two dioxin-responsive genes, cytochrome P-450 1B1 (CYP1B1) and downstream of tyrosine kinases (p62(dok)), in the endometrium of women with or without endometriosis using semi-quantitative reverse transcription-polymerase chain reaction. All the genes were expressed throughout the menstrual cycle. The expression level of p62(dok) was higher in the proliferative phase than in the secretory phase. In contrast, the expression levels of AhR, Arnt and CYP1B1 seemed to be constant during the cycle. In terms of the comparison between non-endometriosis and endometriosis group, the mRNA levels of AhR, Arnt, CYP1B1 and p62(dok) were essentially similar. Interestingly, AhR mRNA level was significantly lower in smokers than in non-smokers. Based on the regression analysis, significant linear and positive correlations were observed between AhR and Arnt mRNA levels, and between Arnt and p62(dok) mRNA levels. In summary, expression of AhR and dioxin-related genes in the endometrium did not differ in women with or without endometriosis.

Differential interactions of bisphenol A and 17beta-estradiol with estrogen receptor alpha (ERalpha) and ERbeta

Bisphenol A (BPA), a monomer of plastic used in consumer products, is abundant in the environment and enters the body by ingestion or adsorption. We developed a cell based transcription assay system using a reporter gene under the transcriptional control of estrogen receptor alpha (ERalpha) as well as ERbeta and performed chloramphenicol acetyltransferase (CAT) assay on HeLa cells transfected with either human ERalpha cDNA or ERbeta cDNA to characterize the estrogenic effect of BPA. Estrogenic activity of BPA was detectable at a concentration of 10(-9) M and the activity increased in a dose dependent manner between concentrations of 10(-9) M and 10(-6) M of BPA for both ERalpha and ERbeta. The estrogenic activity of 17beta-estradiol at a concentration of 10(-8) M was almost compatible with that of BPA at the concentration of 10(-6) M of BPA for ERalpha as well as ERbeta. CAT activity was significantly decreased when cells expressing ERalpha were incubated with 10(-6) M of BPA and 10(-8) M of 17beta-estradiol while the activity was essentially the same for ERbeta in the same condition, indicating that BPA exhibits only agonistic action for ERbeta whereas it has dual actions as an agonist and antagonist of estrogen for ERalpha. These results indicates that BPA exerts its effects in ER subtype specific way, thus suggesting that the mode of action of endocrine disruptors are more complex than thought.

Underdeveloped uterus and reduced estrogen responsiveness in mice with disruption of the estrogen-responsive finger protein gene, which is a direct target of estrogen receptor alpha

The biological roles of estrogen-responsive finger protein (efp) in vivo were evaluated in mice carrying a loss-of-function mutation in efp by gene-targeted mutagenesis. Although efp homozygous mice were viable and fertile in both sexes, the uterus that expressed abundant estrogen receptor alpha exhibited significant underdevelopment. When the ovariectomized homozygotes were subjected to 17beta-estradiol treatment, they showed remarkably attenuated responses to estrogen, as exemplified by decreased interstitial water imbibition and retarded endometrial cell increase, at least, attributable to the lower ratio of G1 to S-phase progression in epithelial cells. These results suggest that efp is essential for the normal estrogen-induced cell proliferation and uterine swelling as one of the direct targets of estrogen receptor alpha.

Evidence for the presence of hepatocyte growth factor expression in human ovarian follicles

The presence of hepatocyte growth factor (HGF) in follicular fluid (FF) relative to concentrations of sex steroid hormones and human chorionic gonadotrophin (HCG) was investigated. A total of 69 FF samples were obtained during oocyte retrieval for in-vitro fertilization (IVF) from 11 patients with no apparent endocrine disorders. The concentrations of HGF, oestradiol, progesterone, HCG and testosterone in FF samples were measured by enzyme-linked immunosorbent assay. Transcription of HGF and its receptor, c-met, was detected by reverse transcription-polymerase chain reaction (RT-PCR). Human FF samples contained approximately 90-fold higher amounts of HGF (24.2 +/- 1.2 ng/ml), compared with those of serum (0. 28 +/- 0.04 ng/ml). Concentrations of HGF in FF were positively correlated with those of progesterone (r = 0.649, P < 0.0001) and HCG (r = 0.264, P = 0.026) concentrations in FF. However, HGF concentrations were not significantly correlated with oestradiol and testosterone. HGF in FF was detected by Western blotting, as a single 90 kDa band, corresponding to a single chain form. Additionally, mRNA for both HGF and its receptor were detected in a crude granulosa cell preparation from the pre-ovulatory follicles. These findings suggest that HGF is produced locally in human ovarian follicles and may have a physiological role as an autocrine/paracrine factor.

Differential immunolocalization of estrogen receptor alpha and beta in rat ovary and uterus

In order to investigate the localization of estrogen receptor (ER) alpha and ERbeta in the reproductive organs in the rat, polyclonal antibodies were raised to each specific amino acid sequence. The Western blot with anti-ERalpha antibody showed a 66 kDa band in rat ovary and uterus, while that with anti-ERbeta antibody detected a 55 kDa band in rat ovary, uterus and prostate. The ligand-independent nuclear localization of the two receptors was verified by immunocytochemistry. By immunohistochemistry, the nuclei of glandular and luminal epithelial cells in the uterus were stained with anti-ERalpha antibody, whereas only the nuclei of glandular epithelium cells were stained with anti-ERbeta antibody. In rat ovary, positive signals were shown with anti-ERbeta antibody in the nuclei of granulosacells. No specific immunostaining was observed with anti-ERalpha antibody. Although ERbeta was immunostained at the proestrous, metestrous and diestrous stages, the immunoreactivity of ERbeta was hardly detected at the estrous stage in rat ovary. Thus, we show differential expression of ERalpha and ERbeta in rat uterus and ovary at the protein level, which may provide a clue for understanding the roles of the two receptors in reproductive organs.

Stage-specific expression of estrogen receptor subtypes and estrogen responsive finger protein in preimplantational mouse embryos

In hope of understanding possible roles of estrogen during early embryogenesis, we examined the expression of both estrogen receptor alpha (ER alpha) and ER beta, a recently cloned novel subtype, in mouse oocytes and preimplantation embryos by means of reverse transcription polymerase chain reaction (RT-PCR). To investigate whether estrogen actually exerts its action, we further determined the expression of efp (estrogen-responsive finger protein), a newly characterized estrogen responsive gene belonging to the RING finger family. ER alpha mRNA was detected in whole ovaries, cumulus-oocyte complexes, denuded oocytes, 2-cell and 4-cell embryos, whereas it was undetected in 8-cell embryos. Interestingly it reappeared in morulae and blastocysts. ER beta mRNA was detected similarly to ER alpha except for the absence of ER beta mRNA in morulae. The efp mRNA was detected in whole ovaries, cumulus-oocyte complexes, 4-cell embryos, morulae and blastocysts. The stage specific expression of ER alpha and ER beta along with detection of the product of the estrogen responsive gene in early preimplantation embryos may indicate the possible physiological roles of estrogen in early embryogenesis.

NMDA receptor type 2D gene as target for estrogen receptor in the brain

Although it is well known that estrogen exerts its effect in the brain, the direct target genes transcriptionally regulated by estrogen or rather estrogen receptor (ER) are almost unknown. During the search for estrogen receptor-binding sites from human CpG island library, we found one genomic DNA fragment corresponding to the putative 3'-untranslated region of human NMDA receptor subunit 2D (NR2D) gene. It contained at least four half palindromic estrogen responsive elements (hEREs) within two hundred nucleotides, which was conserved also in the rat. Interestingly, the NR2D mRNA is co-localized with ERalpha and/or ERbeta mRNA in a number of regions of rat brain. We have also demonstrated that NR2D mRNA is up-regulated in rat hypothalamus by estrogen possibly via hEREs identified here. Thus, we suggest that NR2D is one of the direct targets of estrogen receptors which are involved in reproductive as well as non-reproductive actions in the brain.

The complete primary structure of human estrogen receptor beta (hER beta) and its heterodimerization with ER alpha in vivo and in vitro

Human estrogen receptor beta (hER beta) cDNA that encodes the full-length amino acid sequence has been isolated from testis poly(A)+ RNA with the combination of cDNA screening and reverse transcription-PCR. It is composed of a 1590-bp open reading frame and a segment of the 5'- and 3'-untranslated region (UTR) and encodes an additional 53 amino acids in the N-terminal region compared with the previously reported one. Protein interaction between ER alpha and ER beta was demonstrated in vitro by GST pull-down assay and in vivo by immunoprecipitation. Thus, this study indicates that ER alpha and ER beta can interact in vivo, cross-signaling each other.

Isolation of estrogen-responsive genes with a CpG island library

In order to isolate novel estrogen-responsive genes, we utilized a CpG island library in which the regulatory regions of genes are enriched. CpG islands were screened for the ability to bind to a recombinant estrogen receptor protein with a genomic binding site (GBS) cloning method. Six CpG islands were selected, and they contained perfect, imperfect, and/or multiple half-palindromic estrogen-responsive elements (EREs). Northern blot analysis of various human cells showed that all these genomic fragments hybridized to specific mRNAs, suggesting that the genes associated with these EREs might be transcribed in human cells. Then cDNAs associated with two of them, EB1 and EB9, were isolated from libraries of human placenta and MCF-7 cells derived from a human breast cancer, respectively. Both transcripts were increased by estrogen in MCF-7 cells. The increase is inhibited by actinomycin D but not by cycloheximide, indicating that no protein synthesis is required for the up-regulation. The cDNA associated with EB1 encodes a 114-amino-acid protein similar to the cytochrome c oxidase subunit VIIa, named COX7RP (cytochrome c oxidase subunit VII-related protein). The cDNA associated with EB9 is homologous only to an express sequence tag and was named EBAG9 (estrogen receptor-binding fragment-associated gene 9). The palindromic ERE of EB1 is located in an intron of COX7RP, and that of EB9 is in the 5' upstream region of the cDNA. Both EREs had significant estrogen-dependent enhancer activities in a chloramphenicol acetyltransferase assay, when they were inserted into the 5' upstream region of the chicken beta-globin promoter. We therefore propose that the CpG-GBS method described here for isolation of the DNA binding site from the CpG island library would be useful for identification of novel target genes of certain transcription factors.

[New medicinal action of native hormone]

Estrogen is involved in the growth and development of female organs such as uterus and mammary gland. On the other hand, from clinical point of view, it is recently suggested that estrogen is effective to protect postmenopausal women from osteoporosis, coronary heart disease and Alzheimer disease. In order to study the molecular mechanism of estrogen action, we have identified an estrogen responsive gene, efp (estrogen-responsive finger protein), which might mediate estrogen action in various target organs at diverse stages and targeted mutagenesis of efp gene could help clarify physiologic actions of estrogen.

Agonistic effect of tamoxifen is dependent on cell type, ERE-promoter context, and estrogen receptor subtype: functional difference between estrogen receptors alpha and beta

To investigate the functional differences between estrogen receptor (ER) alpha and beta subtypes, we studied the expression and the transcription stimulating activities of these receptors. RT-PCR has demonstrated that ER alpha is expressed at a high level in MCF-7 cells derived from human breast cancer. Both ER alpha and ER beta were expressed at a lower level in HOS-TE85 and Saos2 cells derived from human osteosarcoma. Chloramphenicol acetyltransferase reporter assay detected the transcriptional activation by the endogenous receptor only in MCF-7 cells. Agonistic effect of tamoxifen was observed as strong as that of 17beta-estradiol on ERE activation in MCF-7 cells at the concentration of 10(-7) M when ERE-containing reporter is constructed with beta-globin promoter. The effect of tamoxifen was not apparent when the reporter was constructed with thymidine kinase promoter, suggesting that the differential gene activation between tamoxifen and estrogen may take place depending upon ERE-promoter context. Agonistic activity of tamoxifen was also detected in COS-7 and Saos-2 cells, but not in HEC-1 cells derived from human endometrial carcinoma via exogenously expressed ER. Interestingly, this effect was ER alpha specific. Thus, we demonstrate that agonistic effect of tamoxifen depends on the cell type, ERE-promoter context, and ER subtype. These parameters would explain at least a part of the tissue specific effects of antiestrogens in vivo.