Form of dietary selenium affects mRNA encoding interferon-stimulated and progesterone-induced genes in the bovine endometrium and conceptus length at maternal recognition of pregnancy

Widespread regions of the southeast United States have soils, and hence forages, deficient in selenium (Se), necessitating Se supplementation to grazing cattle for optimal immune function, growth, and fertility. We have reported that supplementation with an isomolar 1:1 mix (MIX) of inorganic (ISe) and organic (OSe) forms of Se increases early luteal phase (LP) concentrations of progesterone (P4) above that in cows on ISe or OSe alone. Increased early LP P4 advances embryonic development. Our objective was to determine the effects of the form of Se on the development of the bovine conceptus and the endometrium using targeted real-time PCR (qPCR) on day 17 of gestation, the time of maternal recognition of pregnancy (MRP). Angus-cross yearling heifers underwent 45-d Se-depletion then repletion periods, then at least 90 d of supplementation (TRT) with 35 ppm Se per day as either ISe (n = 10) or MIX (n = 10). Heifers were inseminated to a single sire after detected estrus (day 0). On day 17 of gestation, caruncular (CAR) and intercaruncular (ICAR) endometrial samples and the developing conceptus were recovered from pregnant heifers (ISe, n = 6 and MIX, n = 6). qPCR was performed to determine the relative abundance of targeted transcripts in CAR and ICAR samples, with the expression data subjected to one-way ANOVA to determine TRT effects. The effect of TRT on conceptus development was analyzed using a one-tailed Student's t-test. When compared with ISe-treated heifers, MIX heifers had decreased (P < 0.05) abundance of several P4-induced and interferon-stimulated mRNA transcripts, including IFIT3, ISG15, MX1, OAS2, RSAD2, DGAT2, FGF2 in CAR and DKK1 in ICAR samples and tended (P ≤ 0.10) to have decreased mRNA abundance of IRF1, IRF2, FOXL2, and PGR in CAR samples, and HOXA10 and PAQR7 in ICAR samples. In contrast, MIX-supplemented heifers had increased (P < 0.05) mRNA abundance of MSTN in ICAR samples and an increase in conceptus length (ISe: 17.45 ± 3.08 cm vs. MIX: 25.96 ± 3.95 cm; P = 0.05). Notably, myostatin increases glucose secretion into histotroph and contributes to advanced conceptus development. This advancement in conceptus development occurred in the presence of similar concentrations of serum P4 (P = 0.88) and whole blood Se (P = 0.07) at MRP.

Bovine scavenger receptor class A (SR-A) exhibit specific patterns of regulation in the endometrium during the oestrous cycle and early pregnancy

In mammals, tight regulation of maternal endometrial function is critical for pregnancy success. In bovine species, endometrial expression of members of the scavenger receptor class A (SR-A) has been listed in high-throughput analyses, but very little is known about the involvement of these immune factors during implantation in mammals. To provide first insights into the contribution of SR-A to endometrial physiology, we analysed the expression and regulation of all members of SR-A (SR-A1, SR-A3-SR-A6) during the oestrous cycle and early pregnancy in cattle. Levels of SR-A1 were increased on Day 20 of pregnancy, whereas SR-A3 levels were increased on Day 13 of the oestrous cycle and of the pregnancy. Although SR-A4 levels were reduced on Day 20 of the oestrous cycle, they remained high in pregnant animals. SR-A5 levels increased by Day 13 of the oestrous cycle and decreased on Day 20, but remained high in pregnant animals. Interferon-τ does not affect SR-A gene expression, whereas progesterone regulates the expression of the SR-A3 and SR-A5 transcripts. Endometrial SR-A3 appeared significantly higher in cows carrying invitro-produced embryos than in AI cows. Our data suggest that members of the SR-A family are involved in endometrial remodelling and regulation of endometrial gland physiology, both processes being critical for implantation in mammals.

Increased FOXL2 expression alters uterine structures and functions†

The transcription factor forkhead box L2 (FOXL2) regulates sex differentiation and reproductive function. Elevated levels of this transcription factor have been observed in the diseases of the uterus, such as endometriosis. However, the impact of elevated FOXL2 expression on uterine physiology remains unknown. In order to determine the consequences of altered FOXL2 in the female reproductive axis, we generated mice with over-expression of FOXL2 (FOXL2OE) by crossing Foxl2LsL/+ with the Progesterone receptor Pgrcre model. FOXL2OE uterus showed severe morphological abnormality including abnormal epithelial stratification, blunted adenogenesis, increased endometrial fibrosis, and disrupted myometrial morphology. In contrast, increasing FOXL2 levels specifically in uterine epithelium by crossing the Foxl2LsL/+ with the lactoferrin Ltficre mice resulted in the eFOXL2OE mice with uterine epithelial stratification but without defects in endometrial fibrosis and adenogenesis, demonstrating a role of the endometrial stroma in the uterine abnormalities of the FOXL2OE mice. Transcriptomic analysis of 12 weeks old Pgrcre and FOXL2OE uterus at diestrus stage showed multiple signaling pathways related with cellular matrix, wnt/β-catenin, and altered cell cycle. Furthermore, we found FOXL2OE mice were sterile. The infertility was caused in part by a disruption of the hypophyseal ovarian axis resulting in an anovulatory phenotype. The FOXL2OE mice failed to show decidual responses during artificial decidualization in ovariectomized mice demonstrating the uterine contribution to the infertility phenotype. These data support that aberrantly increased FOXL2 expressions in the female reproductive tract can disrupt ovarian and uterine functions.

FOXL2 is a Progesterone Target Gene in the Endometrium of Ruminants

Forkhead Box L2 (FOXL2) is a member of the FOXL class of transcription factors, which are essential for ovarian differentiation and function. In the endometrium, FOXL2 is also thought to be important in cattle; however, it is not clear how its expression is regulated. The maternal recognition of pregnancy signal in cattle, interferon-Tau, does not regulate FOXL2 expression. Therefore, in the present study, we examined whether the ovarian steroid hormones that orchestrate implantation regulate FOXL2 gene expression in ruminants. In sheep, we confirmed that FOXL2 mRNA and protein was expressed in the endometrium across the oestrous cycle (day 4 to day 15 post-oestrus). Similar to the bovine endometrium, ovine FOXL2 endometrial expression was low during the luteal phase of the oestrous cycle (4 to 12 days post-oestrus) and at implantation (15 days post-oestrus) while mRNA and protein expression significantly increased during the luteolytic phase (day 15 post-oestrus in cycle). In pregnant ewes, inhibition of progesterone production by trilostane during the day 5 to 16 period prevented the rise in progesterone concentrations and led to a significant increase of FOXL2 expression in caruncles compared with the control group (1.4-fold, p < 0.05). Ovariectomized ewes or cows that were supplemented with exogenous progesterone for 12 days or 6 days, respectively, had lower endometrial FOXL2 expression compared with control ovariectomized females (sheep, mRNA, 1.8-fold; protein, 2.4-fold; cattle; mRNA, 2.2-fold; p < 0.05). Exogenous oestradiol treatments for 12 days in sheep or 2 days in cattle did not affect FOXL2 endometrial expression compared with control ovariectomized females, except at the protein level in both endometrial areas in the sheep. Moreover, treating bovine endometrial explants with exogenous progesterone for 48h reduced FOXL2 expression. Using in vitro assays with COS7 cells we also demonstrated that progesterone regulates the FOXL2 promoter activity through the progesterone receptor. Collectively, our findings imply that endometrial FOXL2 is, as a direct target of progesterone, involved in early pregnancy and implantation.

Connecting links between genetic factors defining ovarian reserve and recurrent miscarriages

PURPOSE

Approximately 1-2% of the women faces three or more successive spontaneous miscarriages termed as recurrent miscarriage (RM). Many clinical factors have been attributed so far to be the potential risk factors in RM, including uterine anomalies, antiphospholipid syndrome, endocrinological abnormalities, chromosomal abnormalities, and infections. However, in spite of extensive studies, reviews, and array of causes known to be associated with RM, about 50% cases encountered by treating physicians remains unknown. The aims of this study were to evaluate recent publications and to explore oocyte-specific genetic factors that may have role in incidence of recurrent miscarriages.

METHOD

Recent studies have identified common molecular factors contributing both in establishment of ovarian reserve and in early embryonic development. Also, studies have pointed out the relationship between the age-associated depletion of OR and increase in the risk of miscarriages, thus suggestive of an interacting biology. Here, we have gathered literature evidences in establishing connecting links between genetic factors associated with age induced or pathological OR depletion and idiopathic RM, which are the two extreme ends of female reproductive pathology.

CONCLUSION

In light of connecting etiological link between infertility and RM as reviewed in this study, interrogating the oocyte-specific genes with suspected roles in reproductive biology, in cases of unexplained RM, may open new possibilities in widening our understanding of RM pathophysiology.

Ovarian stromal cells as a source of cancer-associated fibroblasts in human epithelial ovarian cancer: A histopathological study

Fibroblasts are a major component of cancer tissue and known to contribute to cancer progression. However, it remains unknown whether they are derived from local fibroblasts or of other origin. This study was designed to identify the contribution of local stromal cells to cancer stroma in human epithelial ovarian cancer. Seventy-six cases of surgically resected primary ovarian carcinoma (48 cases confined to the ovaries and 28 cases with distant metastases) and 17 cases of secondary ovarian tumor (e.g. colon cancer metastasized to the ovary) were enrolled in this study. The tissues were immunostained for forkhead box protein L2 (FOXL2), a transcription factor crucial for ovarian development and function, and markers for cancer-associated fibroblasts (CAFs) and inflammatory cells. Under normal condition, FOXL2 expression was restricted to ovarian stromal cells and some other types of cells in female genital tracts and never found in other sites of the body. FOXL2-positive cells were found in all primary and secondary tumors in the ovary, and were the dominant stromal cells in most cases. In contrast, only a few FOXL2-positive cells were found in peritoneal seeding sites of four serous carcinoma cases, and all the other tumors at extraovarian sites had no FOXL2-positive cells. FOXL2-positive cells in the ovarian lesion variably expressed CAFs markers, such as alpha-smooth muscle actin and fibroblast activating protein, as determined by double immunostaining. Background inflammation, but not histological subtype or origin of the neoplasm seemed to correlate with the proportion of FOXL2-positive cells. These results suggest that ovarian stromal cells are the main source of cancer stroma in the ovary but do not seem to move to distant sites via circulation together with tumor cells. Our results also support the hypothesis that cancer-associated fibroblasts may originate locally, which was previously demonstrated using animal models.

Uterine Foxl2 regulates the adherence of the Trophectoderm cells to the endometrial epithelium

BACKGROUND

Forkhead Transcription Factor L2 (FOXL2) is a member of the forkhead family with important roles in reproduction. Recent studies showed that FOXL2 is expressed in human and bovine endometrium and that its levels fluctuate during pregnancy. In this study, we aimed at evaluating the expression and function of FOXL2 in embryo implantation.

METHODS

Mouse uteri at different days of pregnancy were isolated and analyzed for the expression and localization of FOXL2. A lentiviral strategy was further employed to either knockdown or overexpress FOXL2 in non-receptive human endometrial AN3-CA cells and in receptive Ishikawa cells, respectively. These genetically modified cells were compared to cells infected with a control lentivirus to determine the function of FOXL2 in trophectoderm cells adherence to Endometrial Epithelium was associated with the expression of genes known to be involved in acquisition of uterine receptivity.

RESULTS

We report that FOXL2 is expressed in both, the luminal epithelium and the myometrium of the mouse uterus and that its expression declines prior to implantation. We found that endometrial cells expressing low FOXL2 levels, either endogenous or genetically manipulated, were associated with a higher attachment rate of mouse blastocysts or human Jeg3 spheroids and mouse blastocysts. In accordance, low-FOXL2 levels were associated with changes in the expression level of components of the Wnt/Fzd and apoptotic pathways, both of which are involved in uterine receptivity. Furthermore, FOXL2 expression was inversely correlated with G-protein signaling protein 2 (Rgs2) and cytokine expression.

CONCLUSIONS

These results suggest that FOXL2 interferes with embryo attachment. Better understanding of the function of FOXL2 in the uterus would possibly suggest novel strategies for treatment of infertility attributed to repeated implantation failure.

Maternal metabolism affects endometrial expression of oxidative stress and FOXL2 genes in cattle

Intensive selection for milk production has led to reduced reproductive efficiency in high-producing dairy cattle. The impact of intensive milk production on oocyte quality as well as early embryo development has been established but few analyses have addressed this question at the initiation of implantation, a critical milestone ensuring a successful pregnancy and normal post-natal development. Our study aimed to determine if contrasted maternal metabolism affects the previously described sensory properties of the endometrium to the conceptus in cattle. Following embryo transfer at Day 7 post-oestrus, endometrial caruncular (CAR) and intercaruncular (ICAR) areas were collected at Day 19 from primiparous postpartum Holstein-Friesian cows that were dried-off immediately after parturition (i.e., never milked; DRY) or milked twice daily (LACT). Gene quantification indicated no significant impact of lactation on endometrial expression of transcripts previously reported as conceptus-regulated (PLET1, PTGS2, SOCS6) and interferon-tau stimulated (RSAD2, SOCS1, SOCS3, STAT1) factors or known as female hormone-regulated genes (FOXL2, SCARA5, PTGS2). Compared with LACT cows, DRY cows exhibited mRNA levels with increased expression for FOXL2 transcription factor and decreased expression for oxidative stress-related genes (CAT, SOD1, SOD2). In vivo and in vitro experiments highlighted that neither interferon-tau nor FOXL2 were involved in transcriptional regulation of CAT, SOD1 and SOD2. In addition, our data showed that variations in maternal metabolism had a higher impact on gene expression in ICAR areas. Collectively, our findings prompt the need to fully understand the extent to which modifications in endometrial physiology drive the trajectory of conceptus development from implantation onwards when maternal metabolism is altered.

Analysis of STAT1 expression and biological activity reveals interferon-tau-dependent STAT1-regulated SOCS genes in the bovine endometrium

Signal transducer and activator of transcription (STAT) proteins are critical for the regulation of numerous biological processes. In cattle, microarray analyses identified STAT1 as a differentially expressed gene in the endometrium during the peri-implantation period. To gain new insights about STAT1 during the oestrous cycle and early pregnancy, we investigated STAT1 transcript and protein expression, as well as its biological activity in bovine tissue and cells of endometrial origin. Pregnancy increased STAT1 expression on Day 16, and protein and phosphorylation levels on Day 20. In cyclic and pregnant females, STAT1 was located in endometrial cells but not in the luminal epithelium at Day 20 of pregnancy. The expression of STAT1 during the oestrous cycle was not affected by progesterone supplementation. In vivo and in vitro, interferon-tau (IFNT) stimulated STAT1 mRNA expression, protein tyrosine phosphorylation and nuclear translocation. Using chromatin immunoprecipitation in IFNT-stimulated endometrial cells, we demonstrated an increase of STAT1 binding on interferon regulatory factor 1 (IRF1), cytokine-inducible SH2-containing protein (CISH), suppressor of cytokine signaling 1 and 3 (SOCS1, SOCS3) gene promoters consistent with the induction of their transcripts. Our data provide novel molecular insights into the biological functions of STAT1 in the various cells composing the endometrium during maternal pregnancy recognition and implantation.

Imprinted and DNA methyltransferase gene expression in the endometrium during the pre- and peri-implantation period in cattle

The endometrium plays a key role in providing an optimal environment for attachment of the preimplantation embryo during the early stages of pregnancy. Investigations over the past 2 decades have demonstrated that vital epigenetic processes occur in the embryo during the preimplantation stages of development. However, few studies have investigated the potential role of imprinted genes and their associated modulators, the DNA methyltransferases (DNMTs), in the bovine endometrium during the pre- and peri-implantation period. Therefore, in the present study we examined the expression profiles of the DNMT genes (3A, 3A2 and 3B) and a panel of the most comprehensively studied imprinted genes in the endometrium of cyclic and pregnant animals. Intercaruncular (Days 5, 7, 13, 16 and 20) and caruncular (Days 16 and 20) regions were analysed for gene expression changes, with protein analysis also performed for DNMT3A, DNMT3A2 and DNMT3B on Days 16 and 20. An overall effect of day was observed for expression of several of the imprinted genes. Tissue-dependent gene expression was detected for all genes at Day 20. Differences in DNMT protein abundance were mostly observed in the intercaruncular regions of pregnant heifers at Day 16 when DNMT3A, DNMT3A2 and DNMT3B were all lower when compared with cyclic controls. At Day 20, DNMT3A2 expression was lower in the pregnant caruncular samples compared with cyclic animals. This study provides evidence that epigenetic mechanisms in the endometrium may be involved with implantation of the embryo during the early stages of pregnancy in cattle.

Determinant molecular markers for peri-gastrulating bovine embryo development

Peri-gastrulation defines the time frame between blastocyst formation and implantation that also corresponds in cattle to elongation, pregnancy recognition and uterine secretion. Optimally, this developmental window prepares the conceptus for implantation, placenta formation and fetal development. However, this is a highly sensitive period, as evidenced by the incidence of embryo loss or early post-implantation mortality after AI, embryo transfer or somatic cell nuclear transfer. Elongation markers have often been used within this time frame to assess developmental defects or delays, originating either from the embryo, the uterus or the dam. Comparatively, gastrulation markers have not received great attention, although elongation and gastrulation are linked by reciprocal interactions at the molecular and cellular levels. To make this clearer, this peri-gastrulating period is described herein with a focus on its main developmental landmarks, and the resilience of the landmarks in the face of biotechnologies is questioned.

Maximal expression of Foxl2 in pituitary gonadotropes requires ovarian hormones

Gonadotropin-releasing hormone (GnRH) and activin regulate synthesis of FSH and ultimately fertility. Recent in vivo studies cast SMAD4 and FOXL2 as master transcriptional mediators of activin signaling that act together and independently of GnRH to regulate Fshb gene expression and female fertility. Ovarian hormones regulate GnRH and its receptor (GNRHR) through negative and positive feedback loops. In contrast, the role of ovarian hormones in regulating activin, activin receptors, and components of the activin signaling pathway, including SMAD4 and FOXL2, remains understudied. The widespread distribution of activin and many of its signaling intermediates complicates analysis of the effects of ovarian hormones on their synthesis in gonadotropes, one of five pituitary cell types. We circumvented this complication by using a transgenic model that allows isolation of polyribosomes selectively from gonadotropes of intact females and ovariectomized females treated with or without a GnRH antagonist. This paradigm allows assessment of ovarian hormonal feedback and distinguishes responses that are either independent or dependent on GnRH. Surprisingly, our results indicate that Foxl2 levels in gonadotropes decline significantly in the absence of ovarian input and independently of GnRH. Expression of the genes encoding other members of the activin signaling pathway are unaffected by loss of ovarian hormonal feedback, highlighting their selective effect on Foxl2. Expression of Gnrhr, a known target of FOXL2, also declines upon ovariectomy consistent with reduced expression of Foxl2 and loss of ovarian hormones. In contrast, Fshb mRNA increases dramatically post-ovariectomy due to increased compensatory input from GnRH. Together these data suggest that ovarian hormones regulate expression of Foxl2 thereby expanding the number of genes controlled by the hypothalamic-pituitary-gonadal axis that ultimately dictate reproductive fitness.

Maternal organism and embryo biosensoring: insights from ruminants

In terms of contribution to pregnancy, the mother not only produces gametes, but also hosts gestation, whose progression in the uterus is conditioned by early events during implantation. In ruminants, this period is associated with elongation of the extra-embryonic tissues, gastrulation of the embryonic disk and cross-talk with the endometrium. Recent data have prompted the need for accurate staging of the bovine conceptus and shown that asynchrony between elongation and gastrulation processes may account for pregnancy failure. Data mining of endometrial gene signatures has allowed the identification of molecular pathways and new factors regulated by the conceptus (e.g. FOXL2, SOCS6). Interferon-tau has been recognised to be the major signal of pregnancy recognition, but prostaglandins and lysophospholipids have also been demonstrated to be critical players at the conceptus-endometrium interface. Interestingly, up-regulation of interferon-regulated gene expression has been identified in circulating immune cells during implantation, making these factors a potential source of non-invasive biomarkers for early pregnancy. Distinct endometrial responses have been shown to be elicited by embryos produced by artificial insemination, in vitro fertilisation or somatic cell nuclear transfer. These findings have led to the concept that endometrium is an early biosensor of embryo quality. This biological property first demonstrated in cattle has been recently extended and associated with embryo selection in humans. Hence, compromised or suboptimal endometrial quality can subtly or deeply affect embryo development, with visible and sometimes severe consequences for placentation, foetal development, pregnancy outcome and the long-term health of the offspring.

Transcervical collection of bovine embryos up to Day 21: an 8-year overview

Transcervical embryo collection is used routinely in the bovine species throughout the world to collect Day 6 to Day 9 embryos (early embryos) for genetic selection. For research purposes, however, the collection of embryos at later stages of pregnancy, i.e., Days 12 to 21 (late embryos), is needed. So far, for the recovery of late embryos, females are euthanized and embryo collection is performed after recovery of the genital tract. To reduce the number of animals used and still provide valuable material for embryo research, we have therefore developed a transcervical technique to collect late embryos. The objective of this study was to compare embryo recovery results at early and late stages within our laboratory. Altogether, 232 cows were used for this study. One hundred forty-five flushes were performed to collect embryos from Days 6 to 9, and 251 flushes were performed to collect embryos from Days 12 to 21. For the early embryos, a classical three-way collection equipment was used. To collect the late embryos, the same equipment was used, but the extensible flexible catheter that goes inside the external rigid catheter was removed, so that larger embryos could be collected through the remaining larger hole (two-way collection). All females were submitted to ovum pick up to remove the dominant follicle and were subsequently superovulated with FSH. Luteolysis was induced 48 hours before artificial insemination. Two artificial inseminations were performed with frozen semen, 48 and 56 hours after PGF2α injection. Before embryo collection, cows were treated with an epidural injection of a local anesthetic drug. The presence of CL was checked, and they were counted by rectal palpation. For all collections, the cervix was prepared with the initial introduction of a dilator. Then, the catheter was introduced in one horn, and the cuff was inflated as low as possible. For the collection of late embryos, the flushing solution (30 mL) was injected slowly twice to suspend the embryos before flushing the horn with 500 mL, and the same operation was performed on the second horn. There was no significant difference in the number of embryos collected per flush in the early- and late-stage (758 embryos collected, 5.22 ± 6.02 per flush vs. 1238 embryos collected, 4.93 ± 5.07 per flush, respectively). The number of embryos collected per CL, however, was significantly lower in the early versus late group (0.39 ± 0.32% vs. 0.44 ± 0.34%, respectively). The late collection allowed the retrieval of full conceptuses (embryonic and extraembryonic tissues), even at very late stages such as Days 18 to 21. Careful collection is needed, however, so that conceptuses are not damaged or torn: the horn must be massaged gently and the flush should be ideally recovered in one single flow. This technique is a powerful tool to collect the late-stage embryos for research purposes. Because it is not traumatic, animals can be used again for the same procedure.

SOCS genes expression during physiological and perturbed implantation in bovine endometrium

In mammals, suppressor of cytokine signalling (CISH, SOCS1 to SOCS7) factors control signalling pathways involved in the regulation of numerous physiological processes including pregnancy. In order to gain new insights into the biological functions of SOCS in the endometrium, a comprehensive analysis of SOCS gene expression was carried out in bovine caruncular (CAR) and intercaruncular (ICAR) tissues collected i) during the oestrous cycle, ii) at the time of maternal recognition of pregnancy and at implantation in inseminated females, iii) following uterine interferon-tau (IFNT) infusion at day 14 post-oestrus, iv) following a period of controlled intravaginal progesterone release and v) following transfer of embryos by somatic-cell nuclear transfer (SCNT). The regulatory effects of IFNT on in vitro cultured epithelial and stromal cells were also examined. Altogether, our data showed that CISH, SOCS4, SOCS5 and SOCS7 mRNA levels were poorly affected during luteolysis and pregnancy. In contrast, SOCS1, SOCS2, SOCS3 and SOCS6 mRNA levels were strongly up-regulated at implantation (day 20 of pregnancy). Experimental in vitro and in vivo models demonstrated that only CISH, SOCS1, SOCS2 and SOCS3 were IFNT-induced genes. Immunohistochemistry showed an intense SOCS3 and SOCS6 staining in the nucleus of luminal and glandular epithelium and of stromal cells of pregnant endometrium. Finally, SOCS3 expression was significantly increased in SCNT pregnancies in keeping with the altered immune function previously reported in this model of compromised implantation. Collectively, our data suggest that spatio-temporal changes in endometrial SOCS gene expression reflect the acquisition of receptivity, maternal recognition of pregnancy and implantation.

FOXL2 in human endometrium: hyperexpressed in endometriosis

The present study investigated expression and protein localization of FOXL2 messenger RNA (mRNA) in endometrium of healthy women and in patients with endometriosis during endometrial cycle. In endometriotic lesions, FOXL2 mRNA and protein were evaluated and a possible correlation with activin A mRNA expression changes was also studied. Endometrium was collected from healthy women (n = 52) and from women with endometriosis (n = 31) by hysteroscopy; endometriotic tissues were collected by laparoscopy (n = 38). FOXL2 gene expression analysis in endometrium of healthy women showed a significant expression and no significant changes in mRNA levels between proliferative and secretory phases; a similar pattern was observed in endometrium of patients with endometriosis. Immunohistochemical evaluation showed that FOXL2 protein localized in stromal and glandular cells and colocalized with SUMO-1. FOXL2 mRNA expression was 3-fold higher in endometriosis than in healthy endometrium (P < .01) and a positive correlation between FOXL2 and activin A mRNA was found (P < .05) in endometriosis. In conclusion, FOXL2 mRNA expression and its protein localization do not change during endometrial cycle in eutopic endometrium from healthy individuals or patients with endometriosis; the hyperexpression of FOXL2 in endometriotic lesions suggests an involvement of this transcriptional regulator, probably associated with activin A expression and related to the pathogenesis of endometriosis.