Fatty Acid Mimetic Fragments as Liver Receptor Homologue-1 Modulators

The phospholipid-sensing transcription factor liver receptor homologue-1 (LRH-1) is mainly found in the liver, intestine, and pancreas where it participates in the transcriptional regulation of genes involved in cholesterol and glucose metabolism, inflammation, and endoplasmic reticulum stress. It holds promise as a target in metabolic disease and hepatic/intestinal inflammation treatment, and preliminary evidence suggests potential of LRH-1 modulation for contraception, but LRH-1 modulators are very rare. Based on phospholipid binding to LRH-1, we hypothesized potential for fatty acid mimetics as LRH-1 modulators and discovered new ligand chemotypes by focused fragment screening. Preliminary SAR elucidation, orthogonal activity validation, and target engagement studies highlighted two fragment-like leads for LRH-1 agonist development.

Exploring the distribution of polymorphism across diverse breeds Worldwide in the bovine NR5A2 gene and its correlation with number of mature follicles and corpus albicans

The Nuclear receptor subfamily 5 group A member 2 (NR5A2) gene plays a pivotal role in ovarian development, ovulation, and reproductive traits. There is a lack of studies on its impact on ovarian traits and reproductive traits in cattle. This study aimed to explore NR5A2 gene polymorphisms associations with reproductive traits and investigate the distribution of NR5A2 gene polymorphisms across diverse bovine breeds worldwide. We identified a novel 17-bp deletion within the NR5A2 gene specifically in Chinese Holstein cows (n = 1033) leading to the observation of two genotypes DD and ID. Subsequent association analysis revealed a significant correlation between the 'ID' genotype at this locus and a larger number of corpus albicans (p = 0.042) in diestrus, as well as a higher number of mature follicles (p = 0.038) in estrus. In addition, we also found that the distribution of this deletion exhibits strong regionality across different cattle breeds globally. These findings indicate that the 17-bp deletion mutation within the NR5A2 gene is significantly associated with an increased corpus luteum diameter and a greater number of mature follicles, suggesting its potential utility as a valuable DNA marker for enhancing cow fertility.

Multiomic meta-analysis suggests a correlation between steroid hormone-related genes and litter size in goats

Litter size is a key indicator of production performance in livestock. However, its genetic basis in goats remains poorly understood. In this work, a genome-wide selection sweep analysis (GWSA) on 100 published goat genomes with different litter rates was performed for the first time to identify candidate genes related to kidding rate. This analysis was combined with the public RNA-sequencing data of ovary tissues (follicular phase) from high- and low-yielding goats. A total of 2278 genes were identified by GWSA. Most of these genes were enriched in signaling pathways related to ovarian follicle development and hormone secretion. Moreover, 208 differentially expressed genes between groups were obtained from the ovaries of goats with different litter sizes. These genes were substantially enriched in the cholesterol and steroid synthesis signaling pathways. Meanwhile, the weighted gene co-expression network was used to perform modular analysis of differentially expressed genes. The results showed that seven modules were reconstructed, of which one module showed a very strong correlation with litter size (r = -0.51 and p-value <0.001). There were 51 genes in this module, and 39 hub genes were screened by Pearson's correlation coefficient between core genes > 0.4, correlation coefficient between module members > 0.80 and intra-module connectivity ≥5. Finally, based on the results of GWSA and hub gene Venn analysis, seven key genes (ACSS2, HECW2, KDR, LHCGR, NAMPT, PTGFR and TFPI) were found to be associated with steroid synthesis and follicle growth development. This work contributes to understanding of the genetic basis of goat litter size and provides theoretical support for goat molecular breeding.

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.

Identification of new progestogen-associated networks in mammalian ovulation using bioinformatics

Background

Progesterone plays an essential role in mammalian ovulation. Although much is known about this process, the gene networks involved in ovulation have yet to be established. When analyze the mechanisms of ovulation, we often need to determine key genes or pathways to investigate the reproduction features. However, traditional experimental methods have a number of limitations.

Results

Data, in this study, were acquired from GSE41836 and GSE54584 which provided different samples. They were analyzed with the GEO2R and 546 differentially expressed genes were obtained from two data sets using bioinformatics (absolute log₂ FC > 1, P < 0.05). This study identified four genes (PGR, RELN, PDE10A and PLA2G4A) by protein-protein interaction networks and pathway analysis, and their functional enrichments were associated with ovulation. Then, the top 25 statistical pathway enrichments related to hCG treatment were analyzed. Furthermore, gene network analysis identified certain interconnected genes and pathways involved in progestogenic mechanisms, including progesterone-mediated oocyte maturation, the MAPK signaling pathway, the GnRH signaling pathway and focal adhesion, etc. Moreover, we explored the four target gene pathways. q-PCR analysis following hCG and RU486 treatments confirmed the certain novel progestogenic-associated genes (GNAI1, PRKCA, CAV1, EGFR, RHOA, ZYX, VCL, GRB2 and RAP1A).

Conclusions

The results suggested four key genes, nine predicted genes and eight pathways to be involved in progestogenic networks. These networks provide important regulatory genes and signaling pathways which are involved in ovulation. This study provides a fundamental basis for subsequent functional studies to investigate the regulation of mammalian ovulation.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0577-7) contains supplementary material, which is available to authorized users.

The Orphan Nuclear Receptor Liver Homolog Receptor-1 (Nr5a2) Regulates Ovarian Granulosa Cell Proliferation

In mouse ovaries, liver receptor homolog-1 [nuclear receptor subfamily 5, group A, member 2 (Nr5a2)] expression is restricted to granulosa cells. Mice with Nr5a2 depletion in this cell population fail to ovulate. To determine whether Nr5a2 is essential for granulosa cell proliferation during follicular maturation, we generated granulosa-specific conditional knockout mice (genotype Nr5a2 floxed Cre-recombinase driven by the anti-Müllerian type II receptor, hereafter cKO) with Nr5a2 depletion from primary follicles forward. Proliferation in cKO granulosa cells was substantially reduced relative to control (CON) counterparts, as assessed by bromodeoxyuridine incorporation, proliferative cell nuclear antigen expression, and fluorescent-activated cell sorting. Microarray analysis revealed >2000 differentially regulated transcripts between cKO and CON granulosa cells. Major gene ontology pathways disrupted were proliferation, steroid biosynthesis, female gamete formation, and ovulatory cycle. Transcripts for key cell-cycle genes, including Ccnd1, Ccnd2, Ccne1, Ccne2, E2f1, and E2f2, were in reduced abundance. Transcripts from other cell-cycle-related factors, including Cdh2, Plagl1, Cdkn1a, Prkar2b, Gstm1, Cdk7, and Pts, were overexpressed. Although the follicle-stimulating hormone and estrogen receptors were overexpressed in the cKO animals, in vivo treatment with estradiol-17β failed to rescue decreased proliferation. In vitro inactivation of Nr5a2 using the ML180 reverse agonist similarly decreased cell-cycle-related gene transcripts and downstream targets, as in cKO mice. Pharmacological inhibition of β-catenin, an Nr5a2 cofactor, decreased cyclin gene transcripts and downstream targets. Terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick end labeling immunofluorescence and quantitative polymerase chain reaction of pro/antiapoptotic and autophagic markers showed no differences between cKO and CON granulosa cells. Thus, Nr5a2 is essential for granulosa cell proliferation, but its depletion does not alter the frequency of apoptosis nor autophagy.

MicroRNA-381 suppresses cell growth and invasion by targeting the liver receptor homolog-1 in hepatocellular carcinoma

MicroRNAs (miRs) have emerged as prospective tools for human cancer therapy, including hepatocellular carcinoma (HCC) therapy. Previous studies have suggested that miR-381 functions as oncogenic or tumor-suppressive miRs in other cancer types. However, the role of miR-381 in HCC remains unknown. The present study investigated the expression and functional role of miR-381 in HCC. miR-381 expression was significantly decreased in HCC tissues and cell lines. miR-381 overexpression significantly inhibited HCC cell proliferation and colony formation, induced G0/G1 cell cycle arrest and suppressed cell invasion. Conversely, suppression of miR-381 showed the opposite effect in HCC cells. Bioinformatics analysis and dual-luciferase reporter assay results showed that miR-381 directly targeted the 3'-untranslated region of liver receptor homolog-1 (LRH-1), and quantitative polymerase chain reaction and western blot analysis results showed that miR-381 negatively modulated LRH-1 expression. Data elucidated that miR-381 directly regulated HCC cell growth and invasion, as well as the Wnt signaling pathways, by targeting LRH-1. Clinical tissue detection data revealed an inverse correlation between miR-381 and LRH-1 expression in HCC tissues, further indicating the functional significance of miR-381-LRH-1 in regulating HCC tumorigenesis. The present study indicates that miR-381 may be a novel tumor suppressor that blocks HCC growth and invasion by targeting LRH-1. The results present novel insights into understanding the molecular mechanism underlying HCC tumorigenesis and provide a future direction to the development of therapeutic interventions for HCC.

Unexpected Allosteric Network Contributes to LRH-1 Co-regulator Selectivity

Phospholipids (PLs) are unusual signaling hormones sensed by the nuclear receptor liver receptor homolog-1 (LRH-1), which has evolved a novel allosteric pathway to support appropriate interaction with co-regulators depending on ligand status. LRH-1 plays an important role in controlling lipid and cholesterol homeostasis and is a potential target for the treatment of metabolic and neoplastic diseases. Although the prospect of modulating LRH-1 via small molecules is exciting, the molecular mechanism linking PL structure to transcriptional co-regulator preference is unknown. Previous studies showed that binding to an activating PL ligand, such as dilauroylphosphatidylcholine, favors LRH-1's interaction with transcriptional co-activators to up-regulate gene expression. Both crystallographic and solution-based structural studies showed that dilauroylphosphatidylcholine binding drives unanticipated structural fluctuations outside of the canonical activation surface in an alternate activation function (AF) region, encompassing the β-sheet-H6 region of the protein. However, the mechanism by which dynamics in the alternate AF influences co-regulator selectivity remains elusive. Here, we pair x-ray crystallography with molecular modeling to identify an unexpected allosteric network that traverses the protein ligand binding pocket and links these two elements to dictate selectivity. We show that communication between the alternate AF region and classical AF2 is correlated with the strength of the co-regulator interaction. This work offers the first glimpse into the conformational dynamics that drive this unusual PL-mediated nuclear hormone receptor activation.

Gene expression analysis of pig cumulus-oocyte complexes stimulated in vitro with follicle stimulating hormone or epidermal growth factor-like peptides

BACKGROUND

The gonadotropin-induced resumption of oocyte meiosis in preovulatory follicles is preceded by expression of epidermal growth factor (EGF)-like peptides, amphiregulin (AREG) and epiregulin (EREG), in mural granulosa and cumulus cells. Both the gonadotropins and the EGF-like peptides possess the capacity to stimulate resumption of oocyte meiosis in vitro via activation of a broad signaling network in cumulus cells. To better understand the rapid genomic actions of gonadotropins (FSH) and EGF-like peptides, we analyzed transcriptomes of cumulus cells at 3 h after their stimulation.

METHODS

We hybridized aRNA from cumulus cells to a pig oligonucleotide microarray and compared the transcriptomes of FSH- and AREG/EREG-stimulated cumulus cells with untreated control cells and vice versa. The identified over- and underexpressed genes were subjected to functional genomic analysis according to their molecular and cellular functions. The expression pattern of 50 selected genes with a known or potential function in ovarian development was verified by real-time qRT-PCR.

RESULTS

Both FSH and AREG/EREG increased the expression of genes associated with regulation of cell proliferation, cell migration, blood coagulation and extracellular matrix remodeling. FSH alone induced the expression of genes involved in inflammatory response and in the response to reactive oxygen species. Moreover, FSH stimulated the expression of genes closely related to some ovulatory events either exclusively or significantly more than AREG/EREG (AREG, ADAMTS1, HAS2, TNFAIP6, PLAUR, PLAT, and HSD17B7). In contrast to AREG/EREG, FSH also increased the expression of genes coding for key transcription factors (CEBPB, FOS, ID1/3, and NR5A2), which may contribute to the differing expression profiles of FSH- and AREG/EREG-treated cumulus cells.

CONCLUSIONS

The impact of FSH on cumulus cell gene transcription was higher than the impact of EGF-like factors in terms of the number of cell functions affected as well as the number of over- and underexpressed genes. Both FSH and EGF-like factors overexpressed genes involved in the post-ovulatory switch in steroidogenesis and tissue remodelling. However, FSH was remarkably more efficient in the up-regulation of several specific genes essential for ovulation of matured oocytes and also genes that been reported to play an important role in maturation of cumulus-enclosed oocytes in vitro.