Unique uterine localization and regulation may differentiate LPA3 from other lysophospholipid receptors for its role in embryo implantation

A mutation in LPAR2 activates the miR-939-5p-LPAR2-PI3K/AKT axis to regulate the proliferation and apoptosis of granulosa cells in sheep

Lysophosphatidic acid receptor-2 (LPAR2) is a G protein-coupled receptor, which is involved in various physiological processes such as cell development, proliferation, and apoptosis, and is thought to play an important role in follicular development and reproduction. There is evidence that miRNA recognition elements (MRE) in the gene 3'UTR often contain single nucleotide polymorphisms (SNPs) that can alter the binding affinity of the target miRNA, leading to dysregulation of gene expression. In this study, we detected a SNP in LPAR2 3 'UTR (rs410670692, c.*701C > T) in 384 small-tailed Han sheep using Sequenom MassARRAY®SNP genotyping. Association analysis showed that the SNP was significantly associated with litter size. Then, the effect of LPAR2 rs410670692 mutation on gene expression in sheep hosts was studied by molecular biotechnology. The results showed that the expression of LPAR2 in the TT genotype was significantly higher than that in the CC genotype, which confirmed the existence of rs410670692, a functional SNP, in LPAR2 3'UTR. We then used bioinformatics methods and double luciferase reporter gene assay to predict and confirm LPAR2 SNP rs410670692 as the direct targeting regulatory element of miR-939-5p. Cell transfection experiments further found that SNP rs410670692 down-regulated the mRNA and protein levels of LPAR2 by influencing the binding of miR-939-5p. To understand the function and mechanism of miR-939-5p in sheep granulosa cells (GCs), we conducted cell proliferation and apoptosis experiments which showed inhibited GCs proliferation along with promoted GCs apoptosis upon overexpression of miR-939-5p. Moreover, overexpression of miR-939-5p promotes apoptosis of granulosa cells by blocking the LPAR2-dependent PI3K/Akt signaling pathway. In conclusion, these results indicate that the SNP rs410670692 of LPAR2 is related to the litter size of small-tailed cold sheep, and miR-939-5p can act as a regulatory element binding to the C mutation of rs410670692 to regulate the expression of LPAR2, affect the development of GCs, and thus indirectly affect the litter size of sheep. These studies provide evidence for the involvement of LPAR2 polymorphism in sheep reproduction and are expected to provide new insights into the molecular genetic mechanisms of litter size traits in sheep.

Expression of lysophosphatidic acid receptors in the rat uterus: cellular distribution of protein and gestation-associated changes in gene expression

Though lysophosphatidic acid (LPA) shows a variety of regulatory roles in reproduction, its action mechanisms in the gestational organs are still largely unknown. We here characterized cellular distribution of its six kinds of specific receptors (LPA1-6) in rat uteri by immunohistochemistry and quantitatively analyzed changes in Lpar1-6 mRNAs expression throughout pregnancy. Among LPA1-6, evident expression of LPA3, LPA4, and LPA6 was immunologically detected and less expression of immunoreactive LPA1 and LPA2 was also found. Luminal and glandular epithelial cells, stromal cells, and myometrial cells are sites of positive immunoreactions, and they are all likely to express three or more subtypes. All of Lpar1-6 mRNAs were expressed, and their alterations were variable depending on subtypes and gestational age. The present information suggests that diverse actions of LPA in the uterus involve varied expression of LPA receptors dependent on tissue/cell types, receptor subtype(s), and organ reproductive states and helps to understand uterine biology of LPA.

Distinguish Characters of Luminal and Glandular Epithelium from Mouse Uterus Using a Novel Enzyme-Based Separation Method

The uterine luminal epithelium, glandular epithelium, and stromal cells are vital for the establishment of pregnancy. Previously studies have shown various methods to isolate mouse uterine epithelium and stromal cells, including laser capture microdissection (LCM), enzyme digestion, and immunomagnetic beads. Despite the importance of the endometrial epithelium as the site of implantation and nutritional support for the conceptus, there is no isolated method to separate the luminal epithelium and glandular epithelium. Here, we establish a novel enzyme-based way to separate two types of epithelium and keep their viability. In this article, we analyzed their purity by mRNA level, immunostaining, and transcriptome analysis. Our isolation method revealed several unstudied luminal and glandular epithelial markers in transcriptome analysis. We further demonstrated the viability of the isolated epithelium by 2D and 3D cultures. The results showed that we successfully separated the endometrial luminal epithelium and glandular epithelium. We also provided an experimental model for the following study of the physiological function of the different parts of the uterus and related diseases.

miRNA profiling in intrauterine exosomes of pregnant cattle on day 7

Intrauterine exosomes have been identified to be involved in the embryo development and implantation. The aim of this study was to explore the role of miRNAs in intrauterine exosomes in bovine pregnancy. Intrauterine exosomes were collected from uterine flushing fluids of three donor and three recipient Xianan cows 7 days after fertilization. Intrauterine exosomes miRNAs were extracted and the exosomal miRNAs expression levels were analyzed. Sixty miRNAs differed significantly in their amounts between donors and recipients (p-value < 0.05, |log2(FoldChange)| > 1). Twenty-two miRNAs were upregulated and 38 downregulated in the group of donor cows. The bta-miR-184 was the most significant (P _{Benjamini-Hochberg} < 0.001). A total of 9,775 target genes were predicted using the 60 miRNAs. GO and KEGG analysis showed that the target genes were enriched in several biological processes or pathways associated with embryo implantation and endometrial development, such as cell adhesion, cell junction, focal adhesion, and Rap1 signaling pathway. Our findings suggest that, in cattle early pregnancy stage, these differently expressed miRNAs in intrauterine exosomes involved in embryo implantation and endometrial development, which may exert a significant effect and influence the uterine microenvironment for embryo implantation. These results could provide reference for screening and exploring the intrauterine exosomal miRNA affecting embryo implantation.

Lysophosphatidic Acid Signaling and microRNAs: New Roles in Various Cancers

A wide range of microRNAs (miRNAs) are coded for in the human genome and contribute to the regulation of gene expression. MiRNAs are able to degrade mRNAs and/or prevent the RNA transcript from being translated through complementary binding of the miRNA seed region (nucleotide 2-8) to the 3’-untranslated regions of many mRNAs. Although miRNAs are involved in almost all processes of normal human cells, they are also involved in the abnormal functions of cancer cells. MiRNAs can play dual regulatory roles in cancer, acting either as tumor suppressors or as tumor promoters, depending on the target, tumor type, and stage. In the current review, we discuss the present status of miRNA modulation in the setting of lysophosphatidic acid (LPA) signaling. LPA is produced from lysophosphatidylcholine by the enzyme autotaxin and signals via a range of G protein-coupled receptors to affect cellular processes, which ultimately causes changes in cell morphology, survival, proliferation, differentiation, migration, and adhesion. Several studies have identified miRNAs that are over-expressed in response to stimulation by LPA, but their functional roles have not yet been fully clarified. Since RNA-based treatments hold tremendous promise in the area of personalized medicne, many efforts have been made to bring miRNAs into clinical trials, and this field is evolving at an increasing pace.

Berberine improves ovulation and endometrial receptivity in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a clinical syndrome with reproductive and endocrine disorders. Berberine is a monomer from Chinese herbs such as Coptis chinensis, whose effect on improving ovulation and endometrial receptivity of PCOS is uncertain.

PURPOSE

To evaluate the effect of berberine on improving PCOS and explore the mechanism.

METHODS

The rat model of PCOS was induced by intraperitoneal injection of testosterone propionate. Then they was divided into model (Mod) group, low-dose of berberine (BL) group, high-dose of berberine (BH) group and metformin (Met) group as well as a control (Con) group was established. Ovary morphology, hormone level, glucolipid metabolism were measured. UID-mRNA-seq of ovary tissue was conducted to seek the mechanism of berberine on improving ovulation. Three biomarkers of endometrial receptivity were also examined in endometrium by immunohistochemistry.

RESULTS

The number of cystic follicles was increased while the number of corpus luteum was decreased in the rats of Mod group. These changes could be reversed by high-dose of berberine intervention. Berberine could also decrease the levels of serum luteinizing hormone (LH) and total cholesterol (TC) in PCOS rats. Meanwhile, berberine improved the impairment of abnormal oral glucose tolerance without affecting fasting insulin level and Homeostasis model assessment-insulin resistance (HOMA-IR). Luteinizing hormone/ choriogonadotropin receptor (LHCGR) and cytochrome P450 Family 19 Subfamily A Member 1 (CYP19A1) were focused via RNA-seq of ovary. Protein expression in ovary and mRNA expression in granulosa cell of LHCGR and CYP19A1 were decreased in Mod group and rescued by the intervention of berberine. A decrease of endometrial thickness and an increase of integrin αvβ3 and lysophosphatidic acid receptor 3 (LPAR3) protein expression were observed in Mod group, which could be also reversed by berberbine.

CONCLUSIONS

Berberine could improve ovulation in PCOS and the mechanism might be associated with up-regulating LHCGR and CYP19A1. Berberine could also improve endometrial receptivity through down-regualting αvβ3 and LPAR3.

Jagged1 regulates endometrial receptivity in both humans and mice

The human endometrium undergoes cycle-dependent changes and is only receptive to an implanting blastocyst within a narrow window of 2-4 days in the mid-secretory phase. Such functional changes require delicate interplay between a diversity of factors including cytokines and signaling pathways. The Notch signaling pathway members are expressed in human endometrium. We have previously demonstrated that Notch ligand Jagged1 (JAG1) localizes in the endometrial luminal epithelium (LE) and is abnormally reduced in infertile women during receptivity. However, the functional consequences of reduced JAG1 production on endometrial receptivity to implantation of the blastocyst are unknown. This study aimed to determine the role of JAG1 in regulating endometrial receptivity in humans and mice. Knockdown of JAG1 in both primary human endometrial epithelial cells and Ishikawa cells significantly reduced their adhesive capacity to HTR8/SVneo (trophoblast cell line) spheroids. We confirmed that in human endometrial epithelial cells, JAG1 interacted with Notch Receptor 3 (NOTCH3) and knockdown of JAG1 significantly reduced the expression of Notch signaling downstream target HEY1 and classical receptivity markers. Knockdown of Jag1 in mouse LE significantly impaired blastocyst implantation. We identified ten genes (related to tight junction, infertility, and cell adhesion) that were differentially expressed by Jag1 knockdown in LE in mice. Further analysis of the tight junction family members in both species revealed that JAG1 altered the expression of tight junction components only in mice. Together, our data demonstrated that JAG1 altered endometrial epithelial cell adhesive capacity and regulated endometrial receptivity in both humans and mice likely via different mechanisms.

Steroid hormones and first trimester vascular remodeling

Successful implantation and placentation require neoangiogenesis and the remodeling of the uterine spiral arteries. Progesterone and estradiol control various of the placental functions, but their role in vascular remodeling remains controversial. Therefore, this chapter aims to summarize the current knowledge regarding the role of steroid hormones in the uteroplacental vascular remodeling during the first trimester of gestation.

Relative expression and regulation by short-term fasting of lysophosphatidic acid receptors and autotaxin in white and brown adipose tissue depots

Lysophosphatidic acid (lysoPtdOH) levels have previously been reported to decrease in rodents with short-term fasting. We investigated whether a 16 h fast would change expression of autotaxin, the predominant phospholipase D responsible for adipose-derived lysoPtdOH synthesis, or any of the lysophosphatidic acid receptors (1-6) in four white adipose tissue (WAT) depots and interscapular brown adipose tissue (BAT) in male C57Bl/6J mice fed ad libitum, or fasted for 16 h. Aside from small inductions of Lpar1 in epididymal WAT and Lpar2 in epididymal and inguinal WAT, no significant changes were observed in expression of the Lpar family members, or autotaxin in perirenal, retroperitoneal, epididymal, or inguinal WAT or BAT with fasting. Comparison of the relative expression of Lpar1-6 in various depots showed that Lpar6 was the predominant Lpar in both WAT and BAT, and suggests that further work on the adipose-specific role of Lpar6 is warranted.

Uterine Luminal Epithelium as the Transient Gateway for Embryo Implantation

The uterine luminal epithelium (LE) is the first maternal contact for an implanting embryo. Intrauterine fluid resorption, cessation of LE proliferation and apoptosis, and LE structural changes are prerequisites for establishing transient uterine receptivity for embryo implantation. Vesicle trafficking in the LE and receptor-mediated paracrine and autocrine mechanisms are crucial both for LE preparation and LE communications with the embryo and stroma during the initiation of embryo implantation. This review mainly covers recent in vivo studies in LE of mouse models from 0.5 days post-coitus (D0.5) to ∼D4 20 h when the trophoblasts pass through the LE layer for embryo implantation. The review is organized into three interconnected sections: preimplantation LE preparation for embryo attachment, embryo-LE communications, and LE-stroma communications.

Pleotropic Roles of Autotaxin in the Nervous System Present Opportunities for the Development of Novel Therapeutics for Neurological Diseases

Autotaxin (ATX) is a soluble extracellular enzyme that is abundant in mammalian plasma and cerebrospinal fluid (CSF). It has two known enzymatic activities, acting as both a phosphodiesterase and a phospholipase. The majority of its biological effects have been associated with its ability to liberate lysophosphatidic acid (LPA) from its substrate, lysophosphatidylcholine (LPC). LPA has diverse pleiotropic effects in the central nervous system (CNS) and other tissues via the activation of a family of six cognate G protein-coupled receptors. These LPA receptors (LPARs) are expressed in some combination in all known cell types in the CNS where they mediate such fundamental cellular processes as proliferation, differentiation, migration, chronic inflammation, and cytoskeletal organization. As a result, dysregulation of LPA content may contribute to many CNS and PNS disorders such as chronic inflammatory or neuropathic pain, glioblastoma multiforme (GBM), hemorrhagic hydrocephalus, schizophrenia, multiple sclerosis, Alzheimer's disease, metabolic syndrome-induced brain damage, traumatic brain injury, hepatic encephalopathy-induced cerebral edema, macular edema, major depressive disorder, stress-induced psychiatric disorder, alcohol-induced brain damage, HIV-induced brain injury, pruritus, and peripheral nerve injury. ATX activity is now known to be the primary biological source of this bioactive signaling lipid, and as such, represents a potentially high-value drug target. There is currently one ATX inhibitor entering phase III clinical trials, with several additional preclinical compounds under investigation. This review discusses the physiological and pathological significance of the ATX-LPA-LPA receptor signaling axis and summarizes the evidence for targeting this pathway for the treatment of CNS diseases.

Upregulated microRNA-15b alleviates ovarian cancer through inhitbition of the PI3K/Akt pathway by targeting LPAR3

Ovarian cancer characterizes as the fourth leading consequence of death associated with cancer for women. Accumulating evidence underscores the vital roles of microRNAs (miRNAs) in preventing ovarian cancer development. Besides, induction of the phosphatidylinositol-3 kinase/serine/threonine kinase (PI3K/Akt) pathway associated with the ovarian cancer cell migration and invasion. The study aims to examine the effects of miR-15b on the proliferation, apoptosis, and senescence of human ovarian cancer cells by binding to lysophosphatidic acid receptor 3 (LPAR3) with the involvement of the PI3K/Akt pathway. The positive expression of LPAR3 protein was detected by immunohistochemistry. Then the interaction between miR-15b and LPAR3 was examined. The possible role of miR-15b in ovarian cancer was explored using gain- and loss-of-function experiments. Subsequently, the functions of miR-15b on PI3K/Akt pathway, proliferation, migration, invasion, senescence and apoptosis of ovarian cancer cells were assessed. Furthermore, in vivo tumorigenicity assay in nude mice was performed. LPAR3 was overexpressed, whereas miR-15b was poorly expressed in ovarian cancer tissues. LPAR3 is a direct target of miR-15b. Restored miR-15b promoted Bax expression, apoptosis, and senescence, inhibited expression of LPAR3 and Bcl-2, the extent of PI3K and Akt phosphorylation, as well as ovarian cancer cell proliferation, migration, and invasion. Further, tumor growth was observed to be prevented by miR-15b overexpression. Collectively, our study demonstrates that miR-15b represses the proliferation and drives the senescence and apoptosis of ovarian cancer cells through the suppression of LPAR3 and the PI3K/Akt pathway, highlighting an antitumorigenic role of miR-15b.

Steroid hormones induce in vitro human first trimester trophoblast tubulogenesis by the lysophosphatidic acid pathway

Successful implantation and placentation requires that extravillous cytotrophoblast acquires an endovascular phenotype and remodels uterine spiral arteries. Progesterone (P4) and estradiol (E2) control many of the placental functions, but their role in vascular remodeling remains controversial. Here, we investigated whether P4 and E2 regulate the acquisition of the human first trimester trophoblast endovascular phenotype, and the participation of the lysophosphatidic acid pathway. For this purpose, human first trimester HTR-8/SVneo cells were seeded on Geltrex and assayed for capillary-like tube formation. P4 and E2 increased HTR-8/SVneo tube formation in a concentration-dependent manner and this effect is mediated by the LPA3 receptor. Moreover, sex steroids increased the mRNA levels of the main enzyme that produce lysophosphatidic acid (lysophospholipase-D) but did not regulate LPA3 mRNA levels. Overall, we demonstrate that steroid hormones regulate HTR-8/SVneo trophoblast capillary-like structures formation and we propose that this process could be modulated directly or indirectly by mechanisms associated to the LPA/LPA3 pathway.

Regulation of tumor cell - Microenvironment interaction by the autotaxin-lysophosphatidic acid receptor axis

The lipid mediator lysophosphatidic acid (LPA) in biological fluids is primarily produced by cleavage of lysophospholipids by the lysophospholipase D enzyme Autotaxin (ATX). LPA has been identified and abundantly detected in the culture medium of various cancer cell types, tumor effusates, and ascites fluid of cancer patients. Our current understanding of the physiological role of LPA established its role in fundamental biological responses that include cell proliferation, metabolism, neuronal differentiation, angiogenesis, cell migration, hematopoiesis, inflammation, immunity, wound healing, regulation of cell excitability, and the promotion of cell survival by protecting against apoptotic death. These essential biological responses elicited by LPA are seemingly hijacked by cancer cells in many ways; transcriptional upregulation of ATX leading to increased LPA levels, enhanced expression of multiple LPA GPCR subtypes, and the downregulation of its metabolic breakdown. Recent studies have shown that overexpression of ATX and LPA GPCR can lead to malignant transformation, enhanced proliferation of cancer stem cells, increased invasion and metastasis, reprogramming of the tumor microenvironment and the metastatic niche, and development of resistance to chemo-, immuno-, and radiation-therapy of cancer. The fundamental role of LPA in cancer progression and the therapeutic inhibition of the ATX-LPA axis, although highly appealing, remains unexploited as drug development to these targets has not reached into the clinic yet. The purpose of this brief review is to highlight some unique signaling mechanisms engaged by the ATX-LPA axis and emphasize the therapeutic potential that lies in blocking the molecular targets of the LPA system.

Acidification of uterine epithelium during embryo implantation in mice

Uterine luminal epithelium (LE) is essential for establishing uterine receptivity. Previous microarray analysis revealed upregulation of Atp6v0d2 in gestation day 4.5 (D4.5) LE in mice. Realtime PCR showed upregulation of uterine Atp6v0d2 starting right before embryo attachment ∼D4.0. In situ hybridization demonstrated specific uterine localization of Atp6v0d2 in LE upon embryo implantation. Atp6v0d2 encodes one subunit for vacuolar-type H+-ATPase (V-ATPase), which regulates acidity of intracellular organelles and extracellular environment. LysoSensor Green DND-189 detected acidic signals in LE and glandular epithelium upon embryo implantation, correlating with Atp6v0d2 upregulation in early pregnant uterus. Atp6v0d2-/- females had significantly reduced implantation rate and marginally reduced delivery rate from first mating only, but comparable number of implantation sites and litter size compared to control and comparable fertility to control from subsequent matings, suggesting a nonessential role of Atp6v0d2 subunit in embryo implantation. Successful implantation in both control and Atp6v0d2-/- females was associated with uterine epithelial acidification. No significant compensatory upregulation of Atp6v0d1 mRNA was detected in D4.5 Atp6v0d2-/- uteri. To determine the role of V-ATPase instead of a single subunit in embryo implantation, a specific V-ATPase inhibitor bafilomycin A1 (2.5 μg/kg) was injected via uterine fat pad on D3 18:00 h. This treatment resulted in reduced uterine epithelial acidification, delayed implantation, and reduced number of implantation sites. It also suppressed oil-induced artificial decidualization. These data demonstrate uterine epithelial acidification as a novel phenomenon during embryo implantation and V-ATPase is involved in uterine epithelial acidification and uterine preparation for embryo implantation.

A Brain-Region-Specific Neural Pathway Regulating Germinal Matrix Angiogenesis

Intimate communication between neural and vascular cells is critical for normal brain development and function. Germinal matrix (GM), a key primordium for the brain reward circuitry, is unique among brain regions for its distinct pace of angiogenesis and selective vulnerability to hemorrhage during development. A major neonatal condition, GM hemorrhage can lead to cerebral palsy, hydrocephalus, and mental retardation. Here we identify a brain-region-specific neural progenitor-based signaling pathway dedicated to regulating GM vessel development. This pathway consists of cell-surface sphingosine-1-phosphate receptors, an intracellular cascade including Gα co-factor Ric8a and p38 MAPK, and target gene integrin β8, which in turn regulates vascular TGF-β signaling. These findings provide insights into region-specific specialization of neurovascular communication, with special implications for deciphering potent early-life endocrine, as well as potential gut microbiota impacts on brain reward circuitry. They also identify tissue-specific molecular targets for GM hemorrhage intervention.

Deletion of Lysophosphatidic Acid Receptor 3 (Lpar3) Disrupts Fine Local Balance of Progesterone and Estrogen Signaling in Mouse Uterus During Implantation

Lpar3 encodes LPA3, the third G protein-coupled receptor for lysophosphatidic acid (LPA). Lpar3(-/-) female mice had delayed embryo implantation. Their serum progesterone and estrogen levels were comparable with control on Gestation Day 3.5 (D3.5) at 1100 h. There was reduced cell proliferation in D3.5 and D4.5 Lpar3(-/-) stroma. Progesterone receptor (PGR) disappeared from D4.5 Lpar3(+/+) uterine luminal epithelium (LE) but remained highly expressed in D4.5 Lpar3(-/-) LE. Pgr and PGR- target genes but not estrogen receptor alpha (ERalpha [Esr1]) or ESR target genes, were upregulated in D4.5 Lpar3(-/-) LE. It was hypothesized that suppression of PGR activity in LE could restore on-time uterine receptivity in Lpar3(-/-) mice. A low dose of RU486 (5 μg/mouse) given on D3.5 at 900 h rescued delayed implantation in all pregnant Lpar3(-/-) females and significantly increased number of implantation sites compared to vehicle-treated pregnant Lpar3(-/-) females detected on D4.5. E2 (25 ng/mouse) had a similar effect as 5 μg RU486 on embryo implantation in Lpar3(-/-) females. However, when the ovaries were removed on late D2.5 to create an experimentally induced delayed implantation model, 25 ng E2 activated implantation in Lpar3(+/+) but not Lpar3(-/-) females detected on D4.5. These results demonstrate that deletion of Lpar3 leads to an increased ratio of progesterone signaling/estrogen signaling that can be optimized by low doses of RU486 or E2 to restore on-time implantation in Lpar3(-/-) females.

Seipin deficiency increases chromocenter fragmentation and disrupts acrosome formation leading to male infertility

The Berardinelli–Seip congenital lipodystrophy type 2 (Bscl2, seipin) gene is involved in adipogenesis. Bscl2^−/− males were infertile but had normal mating behavior. Both Bscl2^−/− cauda epididymis sperm count and sperm motility were ~20 × less than control. Bscl2^−/− seminiferous tubules had relatively normal presence of spermatogonia and spermatocytes but had reduced spermatids and sperm. Spatiotemporal expression analyses in Bscl2^+/+ testes demonstrated prominent Bscl2 transcriptional activity in spermatocytes with a plateau reached around postnatal day 28. Seipin protein localization was most abundant in postmeiotic spermatids, suggesting translational repression of Bscl2 mRNA in spermatocytes. In situ end-labeling plus detected increased spermatid apoptosis in Bscl2^−/− testis and annexin V detected increased percentage of positive Bscl2^−/− round spermatids compared with control. Immunofluorescence of marker proteins synaptonemal complex proteins 3 and 1 (SYCP3 and SYCP1), and H3K9me3 (histone H3 trimethylated at lysine 9) in germ cell spreads detected normal meiotic chromosome pairing and homologous chromosome synapsis in Bscl2^−/− spermatocytes, but significantly increased percentages of round spermatids with chromocenter fragmentation and late spermatids and sperm with chromatin vacuoles, indicating defective chromatin condensation in Bscl2^−/− spermatids. Bscl2^−/− late spermatids were disorganized within the seminiferous epithelium, despite normal appearance of Sertoli cells detected by vimentin immunofluorescence. Peanut agglutinin staining revealed various abnormalities of acrosomes in Bscl2^−/− late spermatids, including the absence, irregular-shaped, and fragmented acrosomes, indicating defective acrosome formation in Bscl2^−/− late spermatids, which may affect late spermatid orientation in the seminiferous epithelium. Mitotracker strongly stained the midpiece of control sperm but only very weakly labeled the midpiece of Bscl2^−/− sperm, indicating defective mitochondrial activity that most likely contributed to reduced Bscl2^−/− sperm motility. These data demonstrate novel roles of seipin in spermatid chromatin integrity, acrosome formation, and mitochondrial activity. Increased spermatid apoptosis, increased chromocenter fragmentation, defective chromatin condensation, abnormal acrosome formation, and defective mitochondrial activity contributed to decreased sperm production and defective sperm that resulted in Bscl2^−/− male infertility.

Lysophosphatidic acid signalling in development

Lysophosphatidic acid (LPA) is a bioactive phospholipid that is present in all tissues examined to date. LPA signals extracellularly via cognate G protein-coupled receptors to mediate cellular processes such as survival, proliferation, differentiation, migration, adhesion and morphology. These LPA-influenced processes impact many aspects of organismal development. In particular, LPA signalling has been shown to affect fertility and reproduction, formation of the nervous system, and development of the vasculature. Here and in the accompanying poster, we review the developmentally related features of LPA signalling.

Regulation of T cell motility in vitro and in vivo by LPA and LPA2

Lysophosphatidic acid (LPA) and the LPA-generating enzyme autotaxin (ATX) have been implicated in lymphocyte trafficking and the regulation of lymphocyte entry into lymph nodes. High local concentrations of LPA are thought to be present in lymph node high endothelial venules, suggesting a direct influence of LPA on cell migration. However, little is known about the mechanism of action of LPA, and more work is needed to define the expression and function of the six known G protein-coupled receptors (LPA 1-6) in T cells. We studied the effects of 18∶1 and 16∶0 LPA on naïve CD4+ T cell migration and show that LPA induces CD4+ T cell chemorepulsion in a Transwell system, and also improves the quality of non-directed migration on ICAM-1 and CCL21 coated plates. Using intravital two-photon microscopy, lpa2-/- CD4+ T cells display a striking defect in early migratory behavior at HEVs and in lymph nodes. However, later homeostatic recirculation and LPA-directed migration in vitro were unaffected by loss of lpa2. Taken together, these data highlight a previously unsuspected and non-redundant role for LPA2 in intranodal T cell motility, and suggest that specific functions of LPA may be manipulated by targeting T cell LPA receptors.

Postweaning dietary genistein exposure advances puberty without significantly affecting early pregnancy in C57BL/6J female mice

An epidemiological study indicates higher plasma level of genistein in girls with earlier puberty. This study tests the hypothesis in C57BL/6J mice that postweaning (peripubertal) dietary genistein exposure could result in earlier puberty in females assessed by vaginal opening, estrous cyclicity, corpus luteum and mammary gland development. Newly weaned female mice were fed with 0, 5, 100, or 500 ppm genistein diets. Decreased age at vaginal opening, increased length on estrus stage, and accelerated mammary gland development were detected in 100 and 500 ppm genistein-treated groups. Increased presence of corpus luteum was found in 5 ppm genistein-treated group at 6 weeks old only. Increased expression of epithelial-specific genes but not that of ERα or ERβ was detected in 500 ppm genistein-treated mammary glands at 5 weeks old. No significant adverse effect on embryo implantation was observed. These data demonstrate causal effect of dietary genistein on earlier puberty in female mice.

Differential gene expression profiling of mouse uterine luminal epithelium during periimplantation

Uterine luminal epithelium (LE) is critical for establishing uterine receptivity. Microarray analysis of gestation day 3.5 (D3.5, preimplantation) and D4.5 (postimplantation) LE from natural pregnant mice identified 382 upregulated and 245 downregulated genes in the D4.5 LE. Gene Ontology annotation grouped 186 upregulated and 103 downregulated genes into 22 and 15 enriched subcategories, respectively, in regulating DNA-dependent transcription, metabolism, cell morphology, ion transport, immune response, apoptosis, signal transduction, and so on. Signaling pathway analysis revealed 99 genes in 21 significantly changed signaling pathways, with 14 of these pathways involved in metabolism. In situ hybridization confirmed the temporal expression of 12 previously uncharacterized genes, including Atp6v0a4, Atp6v0d2, F3, Ggh, Tmprss11d, Tmprss13, Anpep, Fxyd4, Naip5, Npl, Nudt19, and Tpm1 in the periimplantation uterus. This study provides a comprehensive picture of the differentially expressed genes in the periimplantation LE to help understand the molecular mechanism of LE transformation upon establishment of uterine receptivity.

Progesterone receptor-mediated regulation of N-acetylneuraminate pyruvate lyase (NPL) in mouse uterine luminal epithelium and nonessential role of NPL in uterine function

N-acetylneuraminate pyruvate lyase (NPL) catalyzes N-acetylneuraminic acid, the predominant sialic acid. Microarray analysis of the periimplantation mouse uterine luminal epithelium (LE) revealed Npl being the most downregulated (35×) gene in the LE upon embryo implantation. In natural pregnant mouse uterus, Npl expression increased 56× from gestation day 0.5 (D0.5) to D2.5. In ovariectomized mouse uterus, Npl was significantly upregulated by progesterone (P4) but downregulated by 17β-estradiol (E2). Progesterone receptor (PR) antagonist RU486 blocked the upregulation of Npl in both preimplantation uterus and P4-treated ovariectomized uterus. Npl was specifically localized in the preimplantation D2.5 and D3.5 uterine LE. Since LE is essential for establishing uterine receptivity, it was hypothesized that NPL might play a critical role in uterine function, especially during embryo implantation. This hypothesis was tested in the Npl^(−/−) mice. No significant differences were observed in the numbers of implantation sites on D4.5, gestation periods, litter sizes, and postnatal offspring growth between wild type (WT) and Npl^(−/−) females from mating with WT males. Npl^(−/−)xNpl^(−/−) crosses produced comparable little sizes as that from WTxWT crosses. Comparable mRNA expression levels of several genes involved in sialic acid metabolism were observed in D3.5 uterus and uterine LE between WT and Npl^(−/−), indicating no compensatory upregulation in the D3.5 Npl^(−/−) uterus and LE. This study demonstrates PR-mediated dynamic expression of Npl in the periimplantation uterus and dispensable role of Npl in uterine function and embryo development.

Distinct spatiotemporal expression of serine proteases Prss23 and Prss35 in periimplantation mouse uterus and dispensable function of Prss35 in fertility

PRSS23 and PRSS35 are homologous proteases originally identified in mouse ovaries. In the periimplantation mouse uterus, Prss23 was highly expressed in the preimplantation gestation day 3.5 (D3.5) uterine luminal epithelium (LE). It disappeared from the postimplantation LE and reappeared in the stromal compartment next to the myometrium on D6.5. It was undetectable in the embryo from D4.5 to D6.5 but highly expressed in the embryo on D7.5. Prss35 became detectable in the uterine stromal compartment surrounding the embryo on D4.5 and shifted towards the mesometrial side of the stromal compartment next to the embryo from D5.5 to D7.5. In the ovariectomized uterus, Prss23 was moderately and Prss35 was dramatically downregulated by progesterone and 17β-estradiol. Based on the expression of Prss35 in granulosa cells and corpus luteum of the ovary and the early pregnant uterus, we hypothesized that PRSS35 might play a role in female reproduction, especially in oocyte development, ovulation, implantation, and decidualization. This hypothesis was tested in Prss35((-/-)) mice, which proved otherwise. Between wild type (WT) and Prss35((-/-)) mice, superovulation of immature females produced comparable numbers of cumulus-oocyte complexes; there were comparable numbers of implantation sites detected on D4.5 and D7.5; there were no obvious differences in the expression of implantation and decidualization marker genes in D4.5 or D7.5 uteri. Comparable mRNA expression levels of a few known protease-related genes in the WT and Prss35((-/-)) D4.5 uteri indicated no compensatory upregulation. Comparable litter sizes from WT × WT and Prss35((-/-))× Prss35((-/-)) crosses suggested that Prss35 gene was unessential for fertility and embryo development. Prss35 gene has been linked to cleft lip/palate in humans. However, no obvious such defects were observed in Prss35((-/-)) mice. This study demonstrates the distinct expression of Prss23 and Prss35 in the periimplantation uterus and the dispensable role of Prss35 in fertility and embryo development.

Physiological and molecular determinants of embryo implantation

Embryo implantation involves the intimate interaction between an implantation-competent blastocyst and a receptive uterus, which occurs in a limited time period known as the window of implantation. Emerging evidence shows that defects originating during embryo implantation induce ripple effects with adverse consequences on later gestation events, highlighting the significance of this event for pregnancy success. Although a multitude of cellular events and molecular pathways involved in embryo-uterine crosstalk during implantation have been identified through gene expression studies and genetically engineered mouse models, a comprehensive understanding of the nature of embryo implantation is still missing. This review focuses on recent progress with particular attention to physiological and molecular determinants of blastocyst activation, uterine receptivity, blastocyst attachment and uterine decidualization. A better understanding of underlying mechanisms governing embryo implantation should generate new strategies to rectify implantation failure and improve pregnancy rates in women.

Interaction between lysophosphatidic acid, prostaglandins and the endocannabinoid system during the window of implantation in the rat uterus

Bioactive lipid molecules as lysophosphatidic acid (LPA), prostaglandins (PG) and endocannabinoids are important mediators of embryo implantation. Based on previous published data we became interested in studying the interaction between these three groups of lipid derivatives in the rat uterus during the window of implantation. Thus, we adopted a pharmacological approach in vitro using LPA, DGPP (a selective antagonist of LPA3, an LPA receptor), endocannabinoids’ receptor selective antagonists (AM251 and AM630) and non selective (indomethacin) and selective (NS-398) inhibitors of cyclooxygenase-1 and 2 enzymes. Cyclooxygenase isoforms participate in prostaglandins’ synthesis. The incubation of the uterus from rats pregnant on day 5 of gestation (implantation window) with LPA augmented the activity and the expression of fatty acid amide hydrolase, the main enzyme involved in the degradation of endocannabinoids in the rodent uteri, suggesting that LPA decreased endocannabinoids’ levels during embryo implantation. It has been reported that high endocannabinoids are deleterious for implantation. Also, LPA increased PGE2 production and cyclooxygenase-2 expression. The incubation of LPA with indomethacin or NS-398 reversed the increment in PGE2 production, suggesting that cyclooxygenase-2 was the isoform involved in LPA effect. PGs are important mediators of decidualization and vascularization at the implantation sites. All these effects were mediated by LPA3, as the incubation with DGPP completely reversed LPA stimulatory actions. Besides, we also observed that endocannabinoids mediated the stimulatory effect of LPA on cyclooxygenase-2 derived PGE2 production, as the incubation of LPA with AM251 or AM630 completely reversed LPA effect. Also, LPA augmented via LPA3 decidualization and vascularization markers. Overall, the results presented here demonstrate the participation of LPA3 in the process of implantation through the interaction with other groups of lipid molecules, prostaglandins and endocannabinoids, which prepare the uterine milieu for embryo invasion during the window of implantation.