Impaired progesterone production in Nr5a2+/- mice leads to a reduction in female reproductive function

miR-27a-3p targets NR5A2 to regulate CYP19A1 expression and 17-β estradiol synthesis in ovine granulosa cells

Although 17-β estradiol (E2) synthesis is important in regulating female fertility, we know little regarding the molecular mechanism of miRNA-regulated ovine E2 synthesis. Here, our experiments with granulosa cells (GCs) from Hu sheep revealed miR-27a-3p involvement in E2 synthesis and its association with ovine litter size. First, we showed that miR-27a-3p of sheep and other mammals share a high nucleotide identity. Next, gain- and loss-of-function assays indicated that miR-27a-3p inhibits CYP19A1 expression and E2 synthesis in GCs. Moreover, we demonstrated that NR5A2 is a direct target of miR-27a-3p. Ovine miR-27a-3p suppresses E2 synthesis via the NR5A2 and CYP19A1 axes. We also identified four single nucleotide polymorphisms in the ovine miR-27a gene, and g.-13 G>A and g 0.24 T > G were significantly associated with the first and the second parity litter size, respectively (P < 0.05). In summary, our findings reveal that miR-27a-3p is a novel regulator of E2 synthesis and may predict litter size of Hu sheep, providing insight into mechanisms underlying granulosa cell function and female fertility.

Liver Receptor homolog-1 Regulates Apoptosis of Bovine Ovarian Granulosa Cells by Progestogen Receptor Signaling Pathway

The purpose of the present investigation was to assess the function of LRH-1 on GCs and the mechanisms involved. Here, LRH- was highly expressed in the bovine GCs of atretic follicles. Treatment with 50 μM of LRH-1 agonist (DLPC) significantly induced the expression of LRH-1 (p < 0.05). In particular, LRH-1 activation blocked the progestogen receptor signaling pathway via downregulating progesterone production and progestogen receptor levels (p < 0.05), but had no effect on 17 beta-estradiol synthesis. Meanwhile, LRH-1 activation promoted the apoptosis of GCs and increased the activity of caspase 3 (p < 0.05). Importantly, upregulating the progestogen receptor signaling pathway with progestogen could attenuate the LRH-1-induced proapoptotic effect. Moreover, treatment with progestogen decreased the activity of the proapoptotic gene caspase 3 and increased the expression of antiapoptotic gene Bcl2 in LRH-1 activated GCs (p < 0.05). Taken together, these results demonstrate that LRH-1 might be dependent on the progestogen receptor signaling pathway to modulate bovine follicular atresia.

Lrh1 can help reprogram sexual cell fate and is required for Sertoli cell development and spermatogenesis in the mouse testis

The mammalian nuclear hormone receptors LRH1 (NR5A2) and SF1 (NR5A1) are close paralogs that can bind the same DNA motif and play crucial roles in gonadal development and function. Lrh1 is essential for follicle development in the ovary and has been proposed to regulate steroidogenesis in the testis. Lrh1 expression in the testis is highly elevated by loss of the sex regulator Dmrt1, which triggers male-to-female transdifferentiation of Sertoli cells. While Sf1 has a well-defined and crucial role in testis development, no function for Lrh1 in the male gonad has been reported. Here we use conditional genetics to examine Lrh1 requirements both in gonadal cell fate reprogramming and in normal development of the three major cell lineages of the mouse testis. We find that loss of Lrh1 suppresses sexual transdifferentiation, confirming that Lrh1 can act as a key driver in reprogramming sexual cell fate. In otherwise wild-type testes, we find that Lrh1 is dispensable in Leydig cells but is required in Sertoli cells for their proliferation, for seminiferous tubule morphogenesis, for maintenance of the blood-testis barrier, for feedback regulation of androgen production, and for support of spermatogenesis. Expression profiling identified misexpressed genes likely underlying most aspects of the Sertoli cell phenotype. In the germ line we found that Lrh1 is required for maintenance of functional spermatogonia, and hence mutants progressively lose spermatogenesis. Reduced expression of the RNA binding factor Nxf2 likely contributes to the SSC defect. Unexpectedly, however, over time the Lrh1 mutant germ line recovered abundant spermatogenesis and fertility. This finding indicates that severe germ line depletion triggers a response allowing mutant spermatogonia to recover the ability to undergo complete spermatogenesis. Our results demonstrate that Lrh1, like Sf1, is an essential regulator of testis development and function but has a very distinct repertoire of functions.

Mifepristone Directly Disrupts Mouse Embryonic Development in Terms of Cellular Proliferation and Maturation In Vitro

Mifepristone (RU-486), a synthetic steroid with potent antiprogestogen and anti-glucocorticoid properties, has been widely used in clinical practice. Its effect on the endometrium, ovary, and fallopian tube has been well reported in many human and animal studies. However, its direct impact on post-implantation embryos remains underexplored. Additionally, some women choose to keep their pregnancy after mifepristone treatment fails. Thus, the potential risk remains controversial. Hence, this study investigated the direct effects of mifepristone on the development of mice blastocysts in vitro in terms of implantation and post-implantation. We detected the level of progesterone (P4) associated with ovulation in vivo. The presence of progesterone receptors (PRs) in blastocysts and post-implantation embryos was also evaluated. Cultured embryos were treated directly with mifepristone. We further examined embryonic implantation and post-implantation of blastocysts in vitro to evaluate the direct effects of mifepristone on embryos by the assessment of embryonic outgrowth and differential cell staining. In the oviduct lumen, the P4 level dramatically increased at 48 h and slightly decreased at 72 and 96 h following ovulation. PR was expressed in blastocysts not only in the preimplantation stage but also in the early post-implantation period. In the evaluation of developmental stages, mifepristone significantly reduced the successful ratio of developing into the late egg cylinder and the early somite stage. In addition, it further decreased the cell number of the embryos' inner cell mass and trophectoderm. We herein provide evidence that mifepristone affects blastocyst viability directly and inhibits post-implantation embryo development in vitro. Furthermore, our data reveal a potential risk of fetus fatality and developmental problems when pregnancies are continued after mifepristone treatment fails.

Nuclear receptors: Key regulators of somatic cell functions in the ovulatory process

The development of the ovarian follicle to its culmination by ovulation is an essential element of fertility. The final stages of ovarian follicular growth are characterized by granulosa cell proliferation and differentiation, and steroid synthesis under the influence of follicle-stimulating hormone (FSH). The result is a population of granulosa cells poised to respond to the ovulatory surge of luteinizing hormone (LH). Members of the nuclear receptor superfamily of transcription factors play indispensable roles in the regulation of these events. The key regulators of the final stages of follicular growth that precede ovulation from this family include the estrogen receptor beta (ESR2) and the androgen receptor (AR), with additional roles for others, including steroidogenic factor-1 (SF-1) and liver receptor homolog-1 (LRH-1). Following the LH surge, the mural and cumulus granulosa cells undergo rapid changes that result in expansion of the cumulus layer, and a shift in ovarian steroid hormone biosynthesis from estradiol to progesterone production. The nuclear receptor best associated with these events is LRH-1. Inadequate cumulus expansion is also observed in the absence of AR and ESR2, but not the progesterone receptor (PGR). The terminal stages of ovulation are regulated by PGR, which increases the abundance of the proteases that are directly responsible for rupture. It further regulates the prostaglandins and cytokines associated with the inflammatory-like characteristics of ovulation. LRH-1 regulates PGR, and is also a key regulator of steroidogenesis, cellular proliferation, and cellular migration, and cytoskeletal remodeling. In summary, nuclear receptors are among the panoply of transcriptional regulators with roles in ovulation, and several are necessary for normal ovarian function.

Sex differences and Tat expression affect dopaminergic receptor expression and response to antioxidant treatment in methamphetamine-sensitized HIV Tat transgenic mice

Methamphetamine (Meth) abuse is a common HIV comorbidity. Males and females differ in their patterns of Meth use, associated behaviors, and responses, but the underlying mechanisms and impact of HIV infection are unclear. Transgenic mice with inducible HIV-1 Tat protein in the brain (iTat) replicate many neurological aspects of HIV infection in humans. We previously showed that Tat induction enhances the Meth sensitization response associated with perturbation of the dopaminergic system, in male iTat mice. Here, we used the iTat mouse model to investigate sex differences in individual and interactive effects of Tat and Meth challenge on locomotor sensitization, brain expression of dopamine receptors (DRDs) and regulatory adenosine receptors (ADORAs). Because Meth administration increases the production of reactive oxygen species (ROS), we also determined whether the effects of Meth could be rescued by concomitant treatment with the ROS scavenger N-acetyl cysteine (NAC). After Meth sensitization and a 7-day abstinence period, groups of Tat+ and Tat-male and female mice were challenged with Meth in combination with NAC. We confirmed that Tat expression and Meth challenge suppressed DRD mRNA and protein in males and females' brains, and showed that females were particularly susceptible to the effects of Meth on D1-like and D2-like DRD subtypes and ADORAs. The expression of these markers differed strikingly between males and females, and between females in different phases of the estrous cycle, in a Tat -dependent manner. NAC attenuated Meth-induced locomotor sensitization and preserved DRD expression in all groups except for Tat + females. These data identify complex interactions between sex, Meth use, and HIV infection on addiction responses, with potential implications for the treatment of male and female Meth users in the context of HIV, especially those with cognitive disorders.

Suppression of Notch Signaling Stimulates Progesterone Synthesis by Enhancing the Expression of NR5A2 and NR2F2 in Porcine Granulosa Cells

The conserved Notch pathway is reported to be involved in progesterone synthesis and secretion; however, the exact effects remain controversial. To determine the role and potential mechanisms of the Notch signaling pathway in progesterone biosynthesis in porcine granulosa cells (pGCs), we first used a pharmacological γ-secretase inhibitor, N-(N-(3,5-difluorophenacetyl-l-alanyl))-S-phenylglycine t-butyl ester (DAPT), to block the Notch pathway in cultured pGCs and then evaluated the expression of genes in the progesterone biosynthesis pathway and key transcription factors (TFs) regulating steroidogenesis. We found that DAPT dose- and time-dependently increased progesterone secretion. The expression of steroidogenic proteins NPC1 and StAR and two TFs, NR5A2 and NR2F2, was significantly upregulated, while the expression of HSD3B was significantly downregulated. Furthermore, knockdown of both NR5A2 and NR2F2 with specific siRNAs blocked the upregulatory effects of DAPT on progesterone secretion and reversed the effects of DAPT on the expression of NPC1, StAR, and HSD3B. Moreover, knockdown of NR5A2 and NR2F2 stimulated the expression of Notch3. In conclusion, the inhibition of Notch signaling stimulated progesterone secretion by enhancing the expression of NPC1 and StAR, and the two TFs NR5A2 and NR2F2 acted as downstream TFs of Notch signaling in regulating progesterone synthesis.

A T > G Mutation in the NR5A2 Gene Is Associated With Litter Size in Hu Sheep Through Upregulation of Promoter Activity by Transcription Factor MTF-1

Nuclear receptor subfamily 5 group A member 2 (NR5A2), also referred to as LRH-1 or FTF, is an orphan nuclear hormone receptor that is involved in regulating embryonic development, ovarian granulosa cell differentiation, gonadal sex differentiation, and steroidogenesis in mammals. However, little is known about how NR5A2 regulates reproduction in sheep. In this study, we amplified the promoter sequence of NR5A2 and determined that its core promoter region ranged from -721 nt to -281 nt. A T > G polymorphism at -700 nt was detected in the core promoter region. Association analysis found that the litter sizes of Hu ewes at their second and average parities with genotype GG (2.20 ± 0.20 and 1.97 ± 0.06, respectively) were significantly higher than those of ewes with genotype TG (1.68 ± 0.10 and 1.74 ± 0.05, respectively) (p < 0.05) and TT (1.67 ± 0.10 and 1.62 ± 0.06, respectively) (p < 0.05). The litter size of Hu ewes at their third parity with genotype GG (2.10 ± 0.10) was significantly higher than that of ewes with genotype TT (1.56 ± 0.12) (p < 0.05). A luciferase assay showed that the -700G allele increased the luciferase activity relative to the -700T allele. Furthermore, the -700T > G polymorphism created a novel binding site for metal-regulatory transcription factor 1 (MTF-1). A competitive electrophoretic mobility shift assay confirmed that MTF-1 specifically bound with the G-type promoter of NR5A2. An overexpression experiment demonstrated that MTF-1 was involved in the alteration of NR5A2 transcription activity and further increased NR5A2 gene mRNA expression. Our findings revealed that the -700T > G polymorphism promoted NR5A2 expression due to the positive effects on NR5A2 gene transcription activity by MTF-1 and thereby increased fecundity in Hu sheep.

Transcriptional Regulation of Ovarian Steroidogenic Genes: Recent Findings Obtained from Stem Cell-Derived Steroidogenic Cells

Ovaries represent one of the primary steroidogenic organs, producing estrogen and progesterone under the regulation of gonadotropins during the estrous cycle. Gonadotropins fluctuate the expression of various steroidogenesis-related genes, such as those encoding steroidogenic enzymes, cholesterol deliverer, and electronic transporter. Steroidogenic factor-1 (SF-1)/adrenal 4-binding protein (Ad4BP)/NR5A1 and liver receptor homolog-1 (LRH-1) play important roles in these phenomena via transcriptional regulation. With the aid of cAMP, SF-1/Ad4BP and LRH-1 can induce the differentiation of stem cells into steroidogenic cells. This model is a useful tool for studying the molecular mechanisms of steroidogenesis. In this article, we will provide insight into the transcriptional regulation of steroidogenesis-related genes in ovaries that are revealed from stem cell-derived steroidogenic cells. Using the cells derived from the model, novel SF-1/Ad4BP- and LRH-1-regulated genes were identified by combined DNA microarray and promoter tiling array analyses. The interaction of SF-1/Ad4BP and LRH-1 with transcriptional regulators in the regulation of ovarian steroidogenesis was also revealed.

The Orphan Nuclear Receptors Steroidogenic Factor-1 and Liver Receptor Homolog-1: Structure, Regulation, and Essential Roles in Mammalian Reproduction

Nuclear receptors are intracellular proteins that act as transcription factors. Proteins with classic nuclear receptor domain structure lacking identified signaling ligands are designated orphan nuclear receptors. Two of these, steroidogenic factor-1 (NR5A1, also known as SF-1) and liver receptor homolog-1 (NR5A2, also known as LRH-1), bind to the same DNA sequences, with different and nonoverlapping effects on targets. Endogenous regulation of both is achieved predominantly by cofactor interactions. SF-1 is expressed primarily in steroidogenic tissues, LRH-1 in tissues of endodermal origin and the gonads. Both receptors modulate cholesterol homeostasis, steroidogenesis, tissue-specific cell proliferation, and stem cell pluripotency. LRH-1 is essential for development beyond gastrulation and SF-1 for genesis of the adrenal, sexual differentiation, and Leydig cell function. Ovary-specific depletion of SF-1 disrupts follicle development, while LRH-1 depletion prevents ovulation, cumulus expansion, and luteinization. Uterine depletion of LRH-1 compromises decidualization and pregnancy. In humans, SF-1 is present in endometriotic tissue, where it regulates estrogen synthesis. SF-1 is underexpressed in ovarian cancer cells and overexpressed in Leydig cell tumors. In breast cancer cells, proliferation, migration and invasion, and chemotherapy resistance are regulated by LRH-1. In conclusion, the NR5A orphan nuclear receptors are nonredundant factors that are crucial regulators of a panoply of biological processes, across multiple reproductive tissues.

Large-scale meta-analysis highlights the hypothalamic-pituitary-gonadal axis in the genetic regulation of menstrual cycle length

The normal menstrual cycle requires a delicate interplay between the hypothalamus, pituitary and ovary. Therefore, its length is an important indicator of female reproductive health. Menstrual cycle length has been shown to be partially controlled by genetic factors, especially in the follicle-stimulating hormone beta-subunit (FSHB) locus. A genome-wide association study meta-analysis of menstrual cycle length in 44 871 women of European ancestry confirmed the previously observed association with the FSHB locus and identified four additional novel signals in, or near, the GNRH1, PGR, NR5A2 and INS-IGF2 genes. These findings not only confirm the role of the hypothalamic-pituitary-gonadal axis in the genetic regulation of menstrual cycle length but also highlight potential novel local regulatory mechanisms, such as those mediated by IGF2.

Dysfunction of Liver Receptor Homolog-1 in Decidua: Possible Relevance to the Pathogenesis of Preeclampsia

Preeclampsia (PE) is a multisystem disorder unique to Homo sapiens that is known to cause maternal and perinatal mortality and morbidity. Between 5–7% of all pregnancies are affected by PE and it is responsible for approximately 50,000 maternal deaths annually. The pathogenesis of PE remains poorly understood. However, the results of this study indicated that insufficient decidualization plays a significant role. NR5A1 and NR5A2 are orphan members of the Ftz-F1 subfamily of nuclear receptors and are involved in mammal follicular development, female reproduction, steroidogenesis, and decidualization. The expression of NR5A1 and NR5A2 in the human decidua and their functions during decidualization were investigated using in vitro cultured cells by real-time PCR, immunohistochemistry, western blotting, and siRNA techniques. The results demonstrated that the levels of NR5A2 mRNA and protein in the decidual tissues of women with PE were lower than those of normal pregnant women. However, the levels of NR5A1 mRNA and protein did not significantly differ between groups. The expression of NR5A2 was upregulated after in vitro decidualization, but the expression of NR5A1 remained low and showed no difference compared with that of the control cells. Knocking down of NR5A2 in human endometrial stromal cells (hESC) resulted in a significant reduction in their expression of decidualization markers (IGFBP1 and PRL) and signaling pathway molecules (WNT4 and BMP2) (P < 0.05). From these data, we concluded that NR5A2 is pivotal for the decidualization of decidual tissues and cultured human endometrial stromal cells. Disorders of the endometrium in decidual tissues may be associated with the abnormal decidualization thought to cause PE.

Regulation of Steroidogenesis, Development, and Cell Differentiation by Steroidogenic Factor-1 and Liver Receptor Homolog-1

Steroidogenic factor-1 (SF-1) and liver receptor homolog-1 (LRH-1) belong to the nuclear receptor superfamily and are categorized as orphan receptors. In addition to other nuclear receptors, these play roles in various physiological phenomena by regulating the transcription of target genes. Both factors share very similar structures and exhibit common functions. Of these, the roles of SF-1 and LRH-1 in steroidogenesis are the most important, especially that of SF-1, which was originally discovered and named to reflect such roles. SF-1 and LRH-1 are essential for steroid hormone production in gonads and adrenal glands through the regulation of various steroidogenesis-related genes. As SF-1 is also necessary for the development of gonads and adrenal glands, it is also considered a master regulator of steroidogenesis. Recent studies have clearly demonstrated that LRH-1 also represents another master regulator of steroidogenesis, which similarly to SF-1, can induce differentiation of non-steroidogenic stem cells into steroidogenic cells. Here, we review the functions of both factors in these steroidogenesis-related phenomena.

Differentiation of mesenchymal stem cells into gonad and adrenal steroidogenic cells

Hormone replacement therapy is necessary for patients with adrenal and gonadal failure. Steroid hormone treatment is also employed in aging people for sex hormone deficiency. These patients undergo such therapies, which have associated risks, for their entire life. Stem cells represent an innovative tool for tissue regeneration and the possibility of solving these problems. Among various stem cell types, mesenchymal stem cells have the potential to differentiate into steroidogenic cells both in vivo and in vitro. In particular, they can effectively be differentiated into steroidogenic cells by expressing nuclear receptor 5A subfamily proteins (steroidogenic factor-1 and liver receptor homolog-1) with the aid of cAMP. This approach will provide a source of cells for future regenerative medicine for the treatment of diseases caused by steroidogenesis deficiencies. It can also represent a useful tool for studying the molecular mechanisms of steroidogenesis and its related diseases.

Reversible infertility in a liver receptor homologue-1 (LRH-1)-knockdown mouse model

Liver receptor homologue-1 (LRH-1) is an orphan nuclear receptor that has been implicated in steroid hormone biosynthesis and fertility. Herein we describe a transgenic inducible short hairpin (sh) RNA mouse model that was used to study the effect of transient LRH-1 knockdown in vivo. Induction of expression of the shRNA directed against LRH-1 for 2–6 weeks resulted in 80% knockdown of LRH-1 protein in the ovary and complete infertility. Gonadotropin hyperstimulation could not rescue the observed defects in ovulation and corpus luteum formation in LRH-1-knockdown mice. The infertility phenotype was fully reversible because LRH-1-knockdown females became pregnant and delivered normal size litters and healthy pups after cessation of LRH-1 shRNA expression. Timed ovarian microarray analysis showed that, in line with the observed decrease in plasma progesterone levels, key steroid biosynthesis genes, namely Star, Cyp11a1, Hsd3b and Scarb1, were downregulated in LRH-1-knockdown ovaries. In contrast with what has been described previously, no clear effect was observed on oestrogenic activity in LRH-1-knockdown mice. Only Sult1e1 and, surprisingly, Hsd17b7 expression was modulated with potentially opposite effects on oestradiol bioavailability. In conclusion, the fully reversible infertility phenotype of LRH-1-knockdown mice shows the feasibility of an LRH-1 antagonist as new contraceptive therapy with a mechanism of action that most prominently affects cholesterol availability and progesterone production.

Regulation of 3β-hydroxysteroid dehydrogenase/Δ⁵-Δ⁴ isomerase: a review

This review focuses on the expression and regulation of 3β-hydroxysteroid dehydrogenase/Δ⁵-Δ⁴ isomerase (3β-HSD), with emphasis on the porcine version. 3β-HSD is often associated with steroidogenesis, but its function in the metabolism of both steroids and xenobiotics is more obscure. Based on currently available literature covering humans, rodents and pigs, this review provides an overview of the present knowledge concerning the regulatory mechanisms for 3β-HSD at all omic levels. The HSD isoenzymes are essential in steroid hormone metabolism, both in the synthesis and degradation of steroids. They display tissue-specific expression and factors influencing their activity, which therefore indicates their tissue-specific responses. 3β-HSD is involved in the synthesis of a number of natural steroid hormones, including progesterone and testosterone, and the hepatic degradation of the pheromone androstenone. In general, a number of signaling and regulatory pathways have been demonstrated to influence 3β-HSD transcription and activity, e.g., JAK-STAT, LH/hCG, ERα, AR, SF-1 and PPARα. The expression and enzymic activity of 3β-HSD are also influenced by external factors, such as dietary composition. Much of the research conducted on porcine 3β-HSD is motivated by its importance for the occurrence of the boar taint phenomenon that results from high concentrations of steroids such as androstenone. This topic is also examined in this review.

Emerging roles for LXRs and LRH-1 in female reproduction

Nutritional status is known to control female reproductive physiology. Many reproductive pathologies such as anorexia nervosa, dystocia and preeclampsia, have been linked to body mass index and to metabolic syndrome. Lipid metabolism has also been associated with ovarian, uterine and placental functions. Among the regulators of lipid homeostasis, the Liver X Receptors (LXRs) and the Liver Receptor Homolog-1 (LRH-1), two members of the nuclear receptor superfamily, play a central role. LXRs are sensitive to intracellular cholesterol concentration and decrease plasma cholesterol, allowing to considering them as "cholesterol sensors". LRH-1 shares many target-genes with LXRs and has been considered for a long time as a real orphan nuclear receptor, but recent findings showed that phospholipids are ligands for this nuclear receptor. Acting in concert, LXRs and LRH-1 could thus be sensitive to slight modifications in cellular lipid balance, tightly maintaining their cellular concentrations. These last years, the use of transgenic mice clarified the roles of these nuclear receptors in many physiological functions. This review will be focused on the roles of LXRs and LRH-1 on female reproduction. Their contribution to ovarian endocrine and exocrine functions, as well as uterine and placental physiology will be discussed. The future challenge will thus be to target these nuclear receptors to prevent lipid-associated reproductive diseases in women.

A novel isoform of liver receptor homolog-1 is regulated by steroidogenic factor-1 and the specificity protein family in ovarian granulosa cells

Liver receptor homolog-1 (LRH-1) is a member of the nuclear receptor 5A (NR5A) subfamily. It is expressed in granulosa cells of the ovary and is involved in steroidogenesis and ovulation. To reveal the transcriptional regulatory mechanism of LRH-1, we determined its transcription start site in the ovary using KGN cells, a human granulosa cell tumor cell line. 5'-rapid amplification of cDNA ends PCR revealed that human ovarian LRH-1 was transcribed from a novel transcription start site, termed exon 2o, located 41 bp upstream of the reported exon 2. The novel LRH-1 isoform was expressed in the human ovary but not the liver. Promoter analysis and an EMSA indicated that a steroidogenic factor-1 (SF-1) binding site and a GC box upstream of exon 2o were required for promoter activity, and that SF-1 and specificity protein (Sp)-1/3 bind to the respective regions in ovarian granulosa cells. In KGN cells, transfection of SF-1 increased ovarian LRH-1 promoter activity and SF-1-dependent reporter activity was further enhanced when peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) was cotransfected. In Drosophila SL2 cells, Sp1 was more effective than Sp3 in enhancing promoter activity, and co-transfection of the NR5A-family synergistically increased activity. Infection with adenoviruses expressing SF-1 or PGC-1α induced LRH-1 expression in KGN cells. These results indicate that the expression of human LRH-1 is regulated in a tissue-specific manner, and that the novel promoter region is controlled by the Sp-family, NR5A-family and PGC-1α in ovarian granulosa cells in a coordinated fashion.

Genome-wide identification of Sox8-, and Sox9-dependent genes during early post-natal testis development in the mouse

The SOX8 and SOX9 transcription factors are involved in, among others, sex differentiation, male gonad development and adult maintenance of spermatogenesis. Sox8(-/-) mice lacking Sox9 in Sertoli cells fail to form testis cords and cannot establish spermatogenesis. Although genetic and histological data show an important role for these transcription factors in regulating spermatogenesis, it is not clear which genes depend upon them at a genome-wide level. To identify transcripts that respond to the absence of Sox8 in all cells and Sox9 in Sertoli cells we measured mRNA concentrations in testicular samples from mice at 0, 6 and 18 days post-partum. In total, 621 and 629 transcripts were found at decreased or increased levels, respectively, at different time points in the mutant as compared to the control samples. These mRNAs were categorized as preferentially expressed in Sertoli cells or germ cells using data obtained with male and female gonad samples and enriched testicular cell populations. Five candidate genes were validated at the protein level. Furthermore, we identified putative direct SOX8 and SOX9 target genes by integrating predicted SOX-binding sites present in potential regulatory regions upstream of the transcription start site. Finally, we used protein network data to gain insight into the effects on regulatory interactions that occur when Sox8 and Sox9 are absent in developing Sertoli cells. The integration of testicular samples with enriched Sertoli cells, germ cells and female gonads enabled us to broadly distinguish transcripts directly affected in Sertoli cells from others that respond to secondary events in testicular cell types. Thus, combined RNA profiling signals, motif predictions and network data identified putative SOX8/SOX9 target genes in Sertoli cells and yielded insight into regulatory interactions that depend upon these transcription factors. In addition, our results will facilitate the interpretation of genome-wide in vivo SOX8 and SOX9 DNA binding data.

Stem cell differentiation into steroidogenic cell lineages by NR5A family

Transformants of mesenchymal stem cells (MSCs) stably expressing steroidogenic factor-1 (SF-1) undergo differentiation into steroidogenic cell-lineages by stimulation with cyclic-adenosine mono-phosphate (cAMP). Another member of NR5A nuclear orphan receptors, Liver-specific receptor homologue-1 (LRH-1), was also able to differentiate MSCs. On the other hand, we found that embryonic stem (ES) cells were hardly induced to differentiate into steroidogenic cell-lineage by the similar treatment. In this study, we developed a novel method to differentiate ES cells into steroidogenic cells. We introduced SF-1 into mouse ES cells at ROSA26 locus under regulation of Tetracycline-off (Tet-off) in order to express SF-1 in the cells at desired period. When SF-1 was induced to express after the ES cells had been differentiated into mesenchymal cell-lineage, steroid hormones were produced from the SF-1 expressing cells. This provides a safer method for supplying sufficient amount of differentiated cells toward future regenerative medicine.

α(1)-Fetoprotein Transcription Factor (FTF)/Liver Receptor Homolog-1 (LRH-1) Is an Essential Lipogenic Regulator

α(1)-Fetoprotein transcription factor (FTF), also known as liver receptor homolog 1 (LRH-1) is highly expressed in liver and intestine, where it is implicated in the regulation of cholesterol, bile acid and steroid hormone homeostasis. FTF is an important regulator of bile acid metabolism. We show here that FTF plays a key regulatory role in lipid homeostasis including triglyceride and cholesterol homeostasis. FTF deficient mice developed lower levels of serum triglyceride and cholesterol as a result of lower expression of several hepatic FTF target genes. Chenodeoxycholic acid repressed FTF expression resulting in a decrease in serum triglyceride in wild-type mice. The absence of chenodeoxycholic acid-mediated repression in FTF(+/-) mice demonstrated the essential role of FTF in triglyceride metabolism. Taken together, our results identify the nuclear receptor FTF as a central regulator of lipid metabolism.

Liver receptor homolog-1 regulates the transcription of steroidogenic enzymes and induces the differentiation of mesenchymal stem cells into steroidogenic cells

Steroidogenic factor-1 (SF-1, also known as Ad4BP) has been demonstrated to be a primary transcriptional regulator of steroidogenic-related genes. However, mRNA for liver receptor homolog-1 (LRH-1), which together with SF-1, belongs to the NR5A nuclear receptor family, is expressed at much higher levels than SF-1 mRNA in the human gonad. In our previous studies, we demonstrated that SF-1 induced the differentiation of bone marrow-derived mesenchymal stem cells (MSCs) into steroidogenic cells such as Leydig or adrenocortical cells. The introduction of LRH-1 into human MSCs (hMSCs) with the aid of cAMP also induced the expression of steroidogenic enzymes, including CYP17, and their differentiation into steroid hormone-producing cells. Promoter analysis, EMSA, and chromatin immunoprecipitation assay using LRH-1-transduced hMSCs indicated that three LRH-1 binding sites were responsible for CYP17 transactivation. Immunohistochemical studies showed that LRH-1 protein was expressed in human Leydig cells. The CYP17 promoter region was highly methylated in hMSCs, whereas it was demethylated by the introduction of LRH-1 and cAMP treatment. These results indicate that LRH-1 could represent another key regulator of the steroidogenic lineage in MSCs and play a vital role in steroid hormone production in human Leydig cells.

Liver receptor homolog 1 is essential for ovulation

Female fertility requires normal ovarian follicular growth and ovulation. The nuclear receptor liver receptor homolog 1 has been implicated in processes as diverse as bile acid metabolism, steroidogenesis, and cell proliferation. In the ovary, Lrh1 is expressed exclusively in granulosa and luteal cells. Using somatic targeted mutagenesis, we show that mice lacking Lrh1 in granulosa cells are sterile, due to anovulation. The preovulatory stimulus fails to elicit cumulus expansion, luteinization, and follicular rupture in these mice. Multiple defects, including severely reduced transactivation of the Lrh1 target gene, nitric oxide synthase 3, leads to increased intrafollicular estradiol levels in the absence of Lrh1. This further causes dysfunction of prostaglandin and hyaluronic acid cascades and interrupts cumulus expansion. Lack of Lrh1 also interferes with progesterone synthesis because of failure of normal expression of the Lrh1 targets, steroidogenic acute regulatory protein and cytochrome P450 side-chain cleavage. In addition, expression of extracellular matrix proteases essential for ovulation is compromised. These results demonstrate that Lrh1 is a regulator of multiple mechanisms essential for maturation of ovarian follicles and for ovulation. Lrh1 is therefore a key modulator of female fertility and a potential target for contraception.

Expression profiling of a high-fertility mouse line by microarray analysis and qPCR

Background

In a recent study it was demonstrated that a largely increased ovulation number is responsible for high prolificacy in two mouse lines selected for fertility performance. The objective of the present study was to identify genes that are involved in increasing the ovulation number in one of these lines, FL1. For differential expression profiling, ovaries of FL1 and of a non-selected control line, DUKsi, both lines derived from the same genetic pool, were analyzed with microarray analysis and quantitative polymerase chain reaction (qPCR). Ovaries from 30 animals of each line were collected at the metestrous stage, combined to 6 pools each, and processed for microarray analysis.

Results

The actual number of ova shed in FL1 exceeded that of the DUKsi control line more than twofold (26.6 vs. 12.9). 148 differentially expressed ovarian transcripts could be identified, 74 of them up- and 74 down-regulated. Of these, 47 significantly mapped to specific Gene Ontology (GO) terms representing different biological processes as steroid metabolism, folliculogenesis, immune response, intracellular signal transduction (particularly of the G protein signaling cascade), regulation of transcription and translation, cell cycle and others. qPCR was used to re-evaluate selected transcripts and to estimate inter-individual variation of expression levels. These data significantly correlated with microarray data in 12 out of 15 selected transcripts but revealed partly large variations of expression levels between individuals.

Conclusion

(1) The abundance of numerous ovarian transcripts was significantly different in FL1 compared to the non-selected control line DUKsi thus suggesting that at least some of the respective genes and corresponding biological processes are involved in improving reproductive traits, particularly by increasing the number of ovulation. (2) Selective qPCR re-evaluation largely confirmed the microarray data and in addition demonstrated that sample pooling can be beneficial to find out group-specific expression profiles despite of large inter-individual variation. (3) The present data will substantially help ongoing genetic association studies to identify candidate genes and causative mutations responsible for increased fertility performance in mice.