Molecular basis for the regulation of the nuclear receptor LRH-1

Transcriptome Insights into Protective Mechanisms of Ferroptosis Inhibition in Aortic Dissection

Aortic dissection (AD) is a life-threatening vascular condition with limited pharmacological options, and shared risk factors with cardiac disease include hypertension, atherosclerosis, smoking, and dyslipidemia. This study investigated Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, in a BAPN/Ang-II-induced mouse model of AD, revealing significant therapeutic potential. Fer-1 significantly reduced AD incidence and mortality by preserving aortic wall integrity. RNA sequencing identified 922 differentially expressed genes, with 416 upregulated and 506 downregulated. Bioinformatics analysis revealed that Fer-1 modulates key regulators, such as MEF2C and KDM5A, impacting immune responses, oxidative stress, apoptosis, and lipid metabolism. Additionally, Fer-1 alters miRNA expression, with the upregulation of miR-361-5p and downregulation of miR-3151-5p, targeting pathways involved in inflammation, oxidative stress, and smooth muscle cell (SMC) phenotypic stability. Functional pathway analysis highlighted the inhibition of actin cytoskeleton, ILK, and IL-17 signaling, essential for SMC differentiation and extracellular matrix remodeling. Gene interaction network analysis identified 21 central molecules, including CXCR3, ACACA, and BPGM, associated with lipid metabolism, inflammation, and vascular remodeling. This research elucidates the mechanism of ferroptosis in AD pathogenesis and establishes Fer-1 as a promising therapeutic intervention. AD and cardiac diseases share molecular mechanisms, risk factors, and pathological processes, positioning AD within the broader scope of cardiovascular pathology. By attenuating lipid peroxidation, oxidative stress, and inflammation, Fer-1 may have cardioprotective effects beyond AD, providing a foundation for future translational research in cardiovascular medicine.

Abnormal phosphorylation of human LRH1 at Ser510 predicts poor prognosis and promotes cell viability in lung squamous cell carcinoma

The nuclear receptor liver receptor homolog 1 (LRH1)/NR5A2 is aberrantly expressed in diverse cancer types, including liver and lung cancers. Since we previously showed that excessive phosphorylation of human LRH1 at S510 (hLRH1pS510-high) is predictable of hepatocellular carcinoma recurrence, we here clarified the clinicopathological and biological significance of hLRH1pS510-high in lung cancer. By immunohistochemistry using an anti-hLRH1pS510 monoclonal antibody, we evaluated the hLRH1pS510 signals in 151 and 150 cases of lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) tissues, respectively, and performed clinicopathological analysis. hLRH1pS510 was localized in the nucleus of tumor cells in LUAD and LUSC tissues with different intensity and proportions among the patients. Of note, the strong hLRH1pS510 signal was occasionally detectable in LUAD and LUSC cells at the expanding tumor edges. A semi-quantitative analysis revealed that 28 (18.4%) and 36 (24.0%) of LUAD and LUSC cases, respectively, exhibited hLRH1pS510-high. Kaplan-Meier plots showed significant differences in the disease-free survival (DFS) between the hLRH1pS510-high and hLRH1pS510-low groups in LUSC, but not in LUAD patients. hLRH1pS510-high was also significantly correlated with recurrence in LUSC patients. Additionally, by multivariate analysis, hLRH1pS510-high represented an independent biomarker for the DFS of LUSC patients. Furthermore, the impact of hLRH1pS510 on the viability of LUSC cells was evaluated by comparing phenotypes among two distinct LUSC cell lines expressing wild-type LRH1, LRH1S510A, and LRH1S510E. Consequently, we demonstrated that phosphorylation of hLRH1S510 accelerates the viability of LUSC cells. Thus, hLRH1pS510 is attractive not only as the predictive biomarker for LUSC but also as the potential therapeutic target.

Fragment-Based Discovery of Drug-like LRH-1 Agonists

The phospholipid sensing transcription factor liver receptor homologue 1 (LRH-1) participates in the transcriptional regulation of metabolic balance and inflammation in liver, pancreas, and other tissues. It is an emerging target for metabolic dysfunction, fatty liver disease, and cancer, but LRH-1 modulators are rare and lack drug-like properties. We discovered new LRH-1 ligands with improved physicochemical features in a fragment-based approach and optimized a venlafaxine-related lead for LRH-1 activation. Despite a strict structure-activity relationship, systematic structural variation resulted in a new LRH-1 agonist scaffold with strong activation efficacy, validated direct and cellular target engagement, and anti-inflammatory and ER-stress-resolving properties in functional cellular settings.

Encoded Display of Chemical Libraries on Nanoparticles as a Versatile Selection Tool To Discover Protein Ligands

DNA-encoded library (DEL) technology is a powerful tool for discovering potent ligands for biological targets but constrained by limitations, including the insolubility of DNA in organic solvents and its instability under various reaction conditions, which restrict the reactivity scope and structural diversity achievable in library synthesis. Here, we present a new strategy called nanoDEL, where library molecules and DNA tags are displayed on the surface of nanoparticles. Since nanoparticles disperse well in both organic solvents and aqueous solutions, DEL synthesis can be accomplished using well-established organic solvent-based conditions, eliminating the need for aqueous conditions. Moreover, nanoDEL enables air-sensitive reactions that are inaccessible with conventional DEL methods relying on aqueous conditions. Notably, in nanoDEL, multiple copies of a DNA tag are attached to an individual nanoparticle to encode a single compound, significantly enhancing tolerance to DNA-damaging conditions. Even when most DNA tags are damaged, sequence analysis remains feasible via amplification of intact tags. Consequently, nanoDEL facilitates the convenient use of existing organic reactions without the necessity to develop DNA-compatible reactions. The potential of nanoDEL was validated by affinity selection against streptavidin as a model system and successfully applied to the discovery of potent small-molecule inhibitors for a kinase and stapled peptide inhibitors targeting a protein-protein interaction, exhibiting dissociation constants in the nanomolar range. Furthermore, we demonstrated that a large combinatorial library can be efficiently synthesized on nanoparticles using a synthetic scheme including moisture-sensitive reaction steps, which are not feasible with conventional DELs.

Blocking the LRH-1/LCN2 axis by ML-180, an LRH-1 inverse agonist, ameliorates osteoarthritis via inhibiting the MAPK pathway

Osteoarthritis (OA) is a chronic and degenerative disease marked by inflammation and extracellular matrix (ECM) degeneration, contributing to synovial inflammation and cartilage destruction. Accumulating evidence has demonstrated that Liver receptor homolog-1 (LRH-1), an orphan nuclear receptor, mediates inflammatory response. However, there is a lack of evidence regarding the regulatory role of LRH-1 in OA pathogenesis. In this study, we confirmed that chondrocytes expressed LRH-1, and observed its upregulation in both IL-1β-treated chondrocytes and cartilage of destabilization of the medial meniscus (DMM)-operated mice. Overexpression of LRH-1 promoted inflammation and dysregulation of ECM metabolism in IL-1β-induced chondrocytes, reversed by inhibition of LRH-1 with ML-180 or gene silencing to protect chondrocytes. Moreover, ML-180 treatment in vivo improved the deteriorated OA phenotypes in mouse models, alleviating OA development. Mechanistically, RNA sequencing revealed that Lipocalin-2 (LCN2), a member of the lipocalin family associated with inflammation, is located downstream of LRH-1 and is positively regulated by it. Furthermore, the LRH-1/LCN2 axis mainly relied on activating the mitogen-activated protein kinase (MAPK) signaling pathway to promote inflammation and dysregulation of ECM metabolism, ultimately damaging chondrocytes. Our findings demonstrate that LRH-1 positively modulates LCN2,activating the MAPK pathway, indicating that targeting the LRH-1/LCN2/MAPK axis may represent a potential therapeutic strategy for OA.

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.

Genetically predicted causal link between the plasma lipidome and pancreatic diseases: a bidirectional Mendelian randomization study

Background

Recent studies have increasingly emphasized the strong correlation between the lipidome and the risk of pancreatic diseases. To determine causality, a Mendelian randomization (MR) analysis was performed to identify connections between the lipidome and pancreatic diseases.

Methods

Statistics from a genome-wide association study of the plasma lipidome, which included a diverse array of 179 lipid species, were obtained from the GeneRISK cohort study with 7,174 participants. Genetic associations with four types of pancreatitis and pancreatic cancer were sourced from the R11 release of the FinnGen consortium. Two pancreatitis datasets from UK Biobank were employed as the validation cohort. MR analysis was conducted to assess the relationship between the genetically predicted plasma lipidome and these pancreatic diseases. Inverse variance weighted was adopted as the main statistical method. Bayesian weighted MR was employed for further verification. The MR-Egger intercept test for pleiotropy and Cochrane's Q statistics test for heterogeneity were performed to ensure the robustness.

Results

MR analysis yielded significant evidence that 26, 25, 2, and 19 lipid species were correlated with diverse outcomes of pancreatitis, and 8 lipid species were correlated with pancreatic cancer. Notably, sterol ester (27:1/20:2) levels (OR: 0.84, 95% CI: 0.78-0.90, P = 5.79 × 10-7) were significantly associated with acute pancreatitis, and phosphatidylcholine (17:0_20:4) levels (OR: 0.89, 95% CI: 0.84-0.94, P = 1.78 × 10-4) and sterol ester (27:1/20:4) levels (OR: 0.90, 95% CI: 0.86-0.95, P = 2.71 × 10-4) levels were significantly associated with chronic pancreatitis after the Bonferroni-corrected test. As for validation, 14 and 9 lipid species were correlated with acute and chronic pancreatitis of UK Biobank. Some lipid classes showed significant effects both in the FinnGen consortium and UK Biobank datasets.

Conclusions

The findings of this study indicate a potential genetic predisposition linking the plasma lipidome to pancreatic diseases and good prospects for future pancreatic disease clinical trials.

Hepatic FXR-FGF4 is required for bile acid homeostasis via an FGFR4-LRH-1 signal node under cholestatic stress

Bile acid (BA) homeostasis is vital for various physiological processes, whereas its disruption underlies cholestasis. The farnesoid X receptor (FXR) is a master regulator of BA homeostasis via the ileal fibroblast growth factor (FGF)15/19 endocrine pathway, responding to postprandial or abnormal transintestinal BA flux. However, the de novo paracrine signal mediator of hepatic FXR, which governs the extent of BA synthesis within the liver in non-postprandial or intrahepatic cholestatic conditions, remains unknown. We identified hepatic Fgf4 as a direct FXR target that paracrinally signals to downregulate Cyp7a1 and Cyp8b1. The effect of FXR-FGF4 is mediated by an uncharted intracellular FGF receptor 4 (FGFR4)-LRH-1 signaling node. This liver-centric pathway acts as a first-line checkpoint for intrahepatic and transhepatic BA flux upstream of the peripheral FXR-FGF15/19 pathway, which together constitutes an integral hepatoenteric control mechanism that fine-tunes BA homeostasis, counteracting cholestasis and hepatobiliary damage. Our findings shed light on potential therapeutic strategies for cholestatic diseases.

LXR-dependent enhancer activation regulates the temporal organization of the liver's response to refeeding leading to lipogenic gene overshoot

Transitions between the fed and fasted state are common in mammals. The liver orchestrates adaptive responses to feeding/fasting by transcriptionally regulating metabolic pathways of energy usage and storage. Transcriptional and enhancer dynamics following cessation of fasting (refeeding) have not been explored. We examined the transcriptional and chromatin events occurring upon refeeding in mice, including kinetic behavior and molecular drivers. We found that the refeeding response is temporally organized with the early response focused on ramping up protein translation while the later stages of refeeding drive a bifurcated lipid synthesis program. While both the cholesterol biosynthesis and lipogenesis pathways were inhibited during fasting, most cholesterol biosynthesis genes returned to their basal levels upon refeeding while most lipogenesis genes markedly overshoot above pre-fasting levels. Gene knockout, enhancer dynamics, and ChIP-seq analyses revealed that lipogenic gene overshoot is dictated by LXRα. These findings from unbiased analyses unravel the mechanism behind the long-known phenomenon of refeeding fat overshoot.

Liver receptor homolog-1: structures, related diseases, and drug discovery

Liver receptor homolog-1 (LRH-1), a member of the nuclear receptor superfamily, is a ligand-regulated transcription factor that plays crucial roles in metabolism, development, and immunity. Despite being classified as an 'orphan' receptor due to the ongoing debate surrounding its endogenous ligands, recent researches have demonstrated that LRH-1 can be modulated by various synthetic ligands. This highlights the potential of LRH-1 as an attractive drug target for the treatment of inflammation, metabolic disorders, and cancer. In this review, we provide an overview of the structural basis, functional activities, associated diseases, and advancements in therapeutic ligand research targeting LRH-1.

Bilirubin is a new ligand for nuclear receptor Liver Receptor Homolog-1

The nuclear receptor Liver Receptor Homolog-1 (LRH-1, NR5A2 ) binds to phospholipids that regulate important LRH-1 functions in the liver. A recent compound screen unexpectedly identified bilirubin, the product of liver heme metabolism, as a possible ligand for LRH-1. Here, we show unconjugated bilirubin directly binds LRH-1 with apparent K d =9.3uM, altering LRH-1 interaction with all transcriptional coregulator peptides tested. Bilirubin decreased LRH-1 protease sensitivity, consistent with MD simulations predicting bilirubin stably binds LRH-1 within the canonical ligand binding site. Bilirubin activated a luciferase reporter specific for LRH-1, dependent on co-expression with the bilirubin membrane transporter SLCO1B1 , but bilirubin failed to activate ligand-binding genetic mutants of LRH-1. Gene profiling in HepG2 cells shows bilirubin selectively regulated transcripts from endogenous LRH-1 ChIP-seq target genes, which was significantly attenuated by either genetic knockdown of LRH-1, or by a specific chemical competitor of LRH-1. Gene set enrichment suggests bilirubin and LRH-1 share roles in cholesterol metabolism and lipid efflux, thus we propose a new role for LRH-1 in directly sensing intracellular levels of bilirubin.

Acetylation of nuclear receptors in health and disease: an update

Lysine acetylation is a common reversible post-translational modification of proteins that plays a key role in regulating gene expression. Nuclear receptors (NRs) include ligand-inducible transcription factors and orphan receptors for which the ligand is undetermined, which together regulate the expression of genes involved in development, metabolism, homeostasis, reproduction and human diseases including cancer. Since the original finding that the ERα, AR and HNF4 are acetylated, we now understand that the vast majority of NRs are acetylated and that this modification has profound effects on NR function. Acetylation sites are often conserved and involve both ordered and disordered regions of NRs. The acetylated residues function as part of an intramolecular signalling platform intersecting phosphorylation, methylation and other modifications. Acetylation of NR has been shown to impact recruitment into chromatin, co-repressor and coactivator complex formation, sensitivity and specificity of regulation by ligand and ligand antagonists, DNA binding, subcellular distribution and transcriptional activity. A growing body of evidence in mice indicates a vital role for NR acetylation in metabolism. Additionally, mutations of the NR acetylation site occur in human disease. This review focuses on the role of NR acetylation in coordinating signalling in normal physiology and disease.

Aberrant phosphorylation of human LRH1 at serine 510 is predictable of hepatocellular carcinoma recurrence

We previously identified the AKT-phosphorylation sites in nuclear receptors and showed that phosphorylation of S379 in mouse retinoic acid γ and S518 in human estrogen receptor α regulate their activity independently of the ligands. Since this site is conserved at S510 in human liver receptor homolog 1 (hLRH1), we developed a monoclonal antibody (mAb) that recognized the phosphorylation form of hLRH1S510 (hLRH1pS510) and verified its clinicopathological significance in hepatocellular carcinoma (HCC). We generated the anti-hLRH1pS510 mAb and assessed its selectivity. We then evaluated the hLRH1pS510 signals in 157 cases of HCC tissues by immunohistochemistry because LRH1 contributes to the pathogenesis of diverse cancers. The developed mAb specifically recognized hLRH1pS510 and worked for immunohistochemistry of formalin-fixed paraffin-embedded tissues. hLRH1pS510 was exclusively localized in the nucleus of HCC cells, but the signal intensity and positive rates varied among the subjects. According to the semi-quantification, 45 cases (34.9%) showed hLRH1pS510-high, and the remaining 112 cases (65.1%) exhibited hLRH1pS510-low. There were significant differences in the recurrence-free survival (RFS) between the two groups, and the 5-year RFS rates in the hLRH1pS510-high and hLRH1pS510-low groups were 26.5% and 46.1%, respectively. In addition, high hLRH1pS510 was significantly correlated with portal vein invasion, hepatic vein invasion, and high levels of serum alpha-fetoprotein (AFP). Furthermore, multivariable analysis revealed that hLRH1pS510-high was an independent biomarker for HCC recurrence. We conclude that aberrant phosphorylation of hLRH1S510 is a predictor of poor prognosis for HCC. The anti-hLRH1pS510 mAb could provide a powerful tool to validate the relevance of hLRH1pS510 in pathological processes such as tumor development and progression.

Comparison of activity, structure, and dynamics of SF-1 and LRH-1 complexed with small molecule modulators

Steroidogenic factor-1 (SF-1) is a phospholipid-sensing nuclear receptor expressed in the adrenal glands, gonads, and hypothalamus which controls steroidogenesis and metabolism. There is significant therapeutic interest in SF-1 because of its oncogenic properties in adrenocortical cancer. Synthetic modulators are attractive for targeting SF-1 for clinical and laboratory purposes due to the poor pharmaceutical properties of its native phospholipid ligands. While small molecule agonists targeting SF-1 have been synthesized, no crystal structures have been reported of SF-1 in complexes with synthetic compounds. This has prevented the establishment of structure-activity relationships that would enable better characterization of ligand-mediated activation and improvement in current chemical scaffolds. Here, we compare the effects of small molecules in SF-1 and its close homolog, liver receptor homolog-1 (LRH-1), and identify several molecules that specifically activate LRH-1. We also report the first crystal structure of SF-1 in complex with a synthetic agonist that displays low nanomolar affinity and potency for SF-1. We use this structure to explore the mechanistic basis for small molecule agonism of SF-1, especially compared to LRH-1, and uncover unique signaling pathways that drive LRH-1 specificity. Molecular dynamics simulations reveal differences in protein dynamics at the pocket mouth as well as ligand-mediated allosteric communication from this region to the coactivator binding interface. Our studies, therefore, shed important insight into the allostery driving SF-1 activity and show potential for modulation of LRH-1 over SF-1.

LRH-1 induces hepatoprotective nonessential amino acids in response to acute liver injury

Acute hepatic injury is observed in response to various stressors, including trauma, ingestion of hepatic toxins, and hepatitis. Investigations to date have focused on extrinsic and intrinsic signals required for hepatocytes to proliferate and regenerate the liver in response to injury, though there is a more limited understanding of induced stress responses promoting hepatocyte survival upon acute injury. In this issue of the JCI, Sun and colleagues detail a mechanism by which local activation of the nuclear receptor liver receptor homolog-1 (LRH-1; NR5A2) directly induces de novo asparagine synthesis and expression of asparagine synthetase (ASNS) in response to injury and show that this response restrains hepatic damage. This work opens up several avenues for inquiry, including the potential for asparagine supplementation to ameliorate acute hepatic injury.

NR5A2 as a potential target for exercise to improve metabolic syndrome

BACKGROUND

Metabolic syndrome is a syndrome of a variety of metabolic disorders. Exercise is beneficial to the human body. However, the association of NR5A2 and exercise with metabolic syndrome remains unclear.

METHODS

Download the GSE10540 and GSE12385 from GEO database. Bioinformatics analysis was used to screen the hub molecular of the metabolic syndrome. Forty 3-week-old C57BL/6J male mice were used in this study. The mean body weight was (17.5 ± 2.1) g. After 10 days of adaptive feeding, they were randomly divided into 4 groups according to the random number table method: Model + Exercise (n = 10), Model (n = 10), Model/NR5A2-OE (n = 10), Model/NR5A2-KO (n = 10). Western Blotting was performed to detect the expression of hub genes and signaling pathway.

RESULTS

There were 349 DEGs in GSE10540 and 49 DEGs in GSE12385. 10 core genes were obtained. GO showed that differentially expressed genes were mainly enriched in vascular morphogenesis, contractile fiber fraction, chemotaxis, and MAPK cascade regulation. KEGG showed that MAPK signaling pathway was a significant section in the metabolic syndrome. PIK3R2, STRA8, FLT1, DMRT1, FGF22, NR5A2, and FLT were up-regulated and PRDM14, POU5F1, and KDR were down-regulated in metabolic syndrome after exercise.

CONCLUSION

The expression of NR5A2 is down-regulated in metabolic syndrome, and exercise can increase the expression level of NR5A2. NR5A2 might be used as a potential target for exercise to improve metabolic syndrome.

The Medicinal Chemistry and Therapeutic Potential of LRH-1 Modulators

The ligand-activated transcription factor liver receptor homologue 1 (LRH-1, NR5A2) is involved in the regulation of metabolic homeostasis, including cholesterol and glucose balance. Preliminary evidence points to therapeutic potential of LRH-1 modulation in diabetes, hepatic diseases, inflammatory bowel diseases, atherosclerosis, and certain cancers, but because of a lack of suitable ligands, pharmacological control of LRH-1 has been insufficiently studied. Despite the availability of considerable structural knowledge on LRH-1, only a few ligand chemotypes have been developed, and potent, selective, and bioavailable tools to explore LRH-1 modulation in vivo are lacking. In view of the therapeutic potential of LRH-1 in prevalent diseases, improved chemical tools are needed to probe the beneficial and adverse effects of pharmacological LRH-1 modulation in sophisticated preclinical models and to further elucidate the receptor's molecular function.

Nuclear receptor subfamily 5 group A member 2 (NR5A2): role in health and diseases

Nuclear receptors are the regulatory molecules that mediate cellular signals as they interact with specific DNA sequences. NR5A2 is a member of NR5A subfamily having four members (Nr5a1-Nr5a4). NR5A2 shows involvement in diverse biological processes like reverse cholesterol transport, embryonic stem cell pluripotency, steroidogenesis, development and differentiation of embryo, and adult homeostasis. NR5A2 haploinsufficiency has been seen associated with chronic pancreatitis, pancreatic and gastrointestinal cancer. There is a close relationship between the progression of pancreatic cancer from chronic pancreatitis, NR5A2 serving a common link. NR5A2 activity is regulated by intracellular phospholipids, transcriptional coregulators and post-translational modifications. The specific ligand of NR5A2 is unknown hence called an orphan receptor, but specific phospholipids such as dilauroyl phosphatidylcholine and diundecanoyl phosphatidylcholine act as a ligand and they are established drug targets in various diseases. This review will focus on the NR5A2 structure, regulation of its activity, and role in biological processes and diseases. In future, need more emphasis on discovering small molecule agonists and antagonist, which act as a drug target for therapeutic applications.

Nuclear receptor NR5A2 negatively regulates cell proliferation and tumor growth in nervous system malignancies

Nervous system malignancies are characterized by rapid progression and poor survival rates. These clinical observations underscore the need for novel therapeutic insights and pharmacological targets. To this end, here, we identify the orphan nuclear receptor NR5A2/LRH1 as a negative regulator of cancer cell proliferation and promising pharmacological target for nervous system-related tumors. In particular, clinical data from publicly available databases suggest that high expression levels of NR5A2 are associated with favorable prognosis in patients with glioblastoma and neuroblastoma tumors. Consistently, we experimentally show that NR5A2 is sufficient to strongly suppress proliferation of both human and mouse glioblastoma and neuroblastoma cells without inducing apoptosis. Moreover, short hairpin RNA-mediated knockdown of the basal expression levels of NR5A2 in glioblastoma cells promotes their cell cycle progression. The antiproliferative effect of NR5A2 is mediated by the transcriptional induction of negative regulators of the cell cycle, CDKN1A (encoding for p21cip1), CDKN1B (encoding for p27kip1) and Prox1 Interestingly, two well-established agonists of NR5A2, dilauroyl phosphatidylcholine (DLPC) and diundecanoyl phosphatidylcholine, are able to mimic the antiproliferative action of NR5A2 in human glioblastoma cells via the induction of the same critical genes. Most importantly, treatment with DLPC inhibits glioblastoma tumor growth in vivo in heterotopic and orthotopic xenograft mouse models. These data indicate a tumor suppressor role of NR5A2 in the nervous system and render this nuclear receptor a potential pharmacological target for the treatment of nervous tissue-related tumors.

Emerging functions of the nuclear receptor LRH-1 in liver physiology and pathology

Nuclear receptors play pleiotropic roles in cell differentiation, development, proliferation, and metabolic processes to govern liver physiology and pathology. The nuclear receptor, liver receptor homolog-1 (LRH-1, NR5A2), originally identified in the liver as a regulator of bile acid and cholesterol homeostasis, was recently recognized to coordinate a multitude of other hepatic metabolic processes, including glucose and lipid processing, methyl group sensing, and cellular stress responses. In this review, we summarize the physiological and pathophysiological functions of LRH-1 in the liver, as well as the molecular mechanisms underlying these processes. This review also focuses on the recent advances highlighting LRH-1 as an attractive target for liver-associated diseases, such as non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC).

NR5A2 transcriptional activation by BRD4 promotes pancreatic cancer progression by upregulating GDF15

NR5A2 is a transcription factor regulating the expression of various oncogenes. However, the role of NR5A2 and the specific regulatory mechanism of NR5A2 in pancreatic ductal adenocarcinoma (PDAC) are not thoroughly studied. In our study, Western blotting, real-time PCR, and immunohistochemistry were conducted to assess the expression levels of different molecules. Wound-healing, MTS, colony formation, and transwell assays were employed to evaluate the malignant potential of pancreatic cancer cells. We demonstrated that NR5A2 acted as a negative prognostic biomarker in PDAC. NR5A2 silencing inhibited the proliferation and migration abilities of pancreatic cancer cells in vitro and in vivo. While NR5A2 overexpression markedly promoted both events in vitro. We further identified that NR5A2 was transcriptionally upregulated by BRD4 in pancreatic cancer cells and this was confirmed by Chromatin immunoprecipitation (ChIP) and ChIP-qPCR. Besides, transcriptome RNA sequencing (RNA-Seq) was performed to explore the cancer-promoting effects of NR5A2, we found that GDF15 is a component of multiple down-regulated tumor-promoting gene sets after NR5A2 was silenced. Next, we showed that NR5A2 enhanced the malignancy of pancreatic cancer cells by inducing the transcription of GDF15. Collectively, our findings suggest that NR5A2 expression is induced by BRD4. In turn, NR5A2 activates the transcription of GDF15, promoting pancreatic cancer progression. Therefore, NR5A2 and GDF15 could be promising therapeutic targets in pancreatic cancer.

Functions of nuclear receptors SUMOylation

The nuclear receptor superfamily is a family of ligand-activated transcription factors that play a key role in cell metabolism and human diseases. They can be modified after translation, such as acetylation, ubiquitination, phosphorylation and SUMOylation. Crosstalk between SUMO and ubiquitin, phosphorylation and acetylation regulates a variety of metabolic and physiological activities. Nuclear receptors play an important role in lipid metabolism, inflammation, bile acid homeostasis and autophagy. SUMOylation nuclear receptors can regulate their function and affect cell metabolism. It also provides a potential therapeutic target for atherosclerosis, tumor and other metabolic and inflammation-related diseases. This review focuses on the function of SUMOylation nuclear receptors.

MicroRNA-3613-5p Promotes Lung Adenocarcinoma Cell Proliferation through a RELA and AKT/MAPK Positive Feedback Loop

Aberrant activation of nuclear factor κB (NF-κB)/RELA is often found in lung adenocarcinoma (LUAD). In this study, we determined that microRNA-3613-5p (miR-3613-5p) plays a crucial role in RELA-mediated post-transcriptional regulation of LUAD cell proliferation. Expression of miR-3613-5p in clinical LUAD specimens is associated with poor prognosis in LUAD. Upregulation of miR-3613-5p promotes LUAD cell proliferation in vitro and in vivo. Our results suggested a mechanism whereby miR-3613-5p expression is induced by RELA through its direct interaction with JUN, thereby stimulating the AKT/mitogen-activated protein kinase (MAPK) pathway by directly targeting NR5A2. In addition, we also found that phosphorylation of AKT1 and MAPK3/1 co-transactivates RELA, thus constituting a RELA/JUN/miR-3613-5p/NR5A2/AKT1/MAPK3/1 positive feedback loop, leading to persistent NF-κB activation. Our findings also revealed that miR-3613-5p plays an oncogenic role in LUAD by promoting cell proliferation and acting as a key regulator of the positive feedback loop underlying the link between the NF-κB/RELA and AKT/MAPK pathways.

Nuclear-mitochondrial crosstalk: On the role of the nuclear receptor liver receptor homolog-1 (NR5A2) in the regulation of mitochondrial metabolism, cell survival, and cancer

Liver receptor homolog-1 (LRH-1, NR5A2) is an orphan nuclear receptor with widespread activities in the regulation of development, stemness, metabolism, steroidogenesis, and proliferation. Many of the LRH-1-regulated processes target the mitochondria and associated activities. While under physiological conditions, a balanced LRH-1 expression and regulation contribute to the maintenance of a physiological equilibrium, deregulation of LRH-1 has been associated with inflammation and cancer. In this review, we discuss the role and mechanism(s) of how LRH-1 regulates metabolic processes, cell survival, and cancer in a nuclear-mitochondrial crosstalk, and evaluate its potential as a pharmacological target.

MRG15 orchestrates rhythmic epigenomic remodelling and controls hepatic lipid metabolism

The rhythmic regulation of transcriptional processes is intimately linked to lipid homeostasis, to anticipate daily changes in energy access. The Rev-erbα-HDAC3 complex was previously discovered to execute the rhythmic repression of lipid genes; however, the epigenetic switch that turns on these genes is less clear. Here, we show that genomic recruitment of MRG15, which is encoded by the mortality factor on chromosome 4 (MORF4)-related gene on chromosome 15, displays a significant diurnal rhythm and activates lipid genes in the mouse liver. RNA polymerase II (Pol II) recruitment and histone acetylation correspond to MRG15 binding, and the rhythm is impaired upon MRG15 depletion, establishing MRG15 as a key modulator in global rhythmic transcriptional regulation. MRG15 interacts with the nuclear receptor LRH-1, rather than with known core clock proteins, and is recruited to genomic loci near lipid genes via LRH-1. Blocking of MRG15 by CRISPR targeting or by the FDA-approved drug argatroban, which is an antagonist to MRG15, attenuates liver steatosis. This work highlights MRG15 as a targetable master regulator in the rhythmic regulation of hepatic lipid metabolism.

Time for a paradigm shift in treating type 1 diabetes mellitus: coupling inflammation to islet regeneration

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that targets the destruction of islet beta-cells resulting in insulin deficiency, hyperglycemia and death if untreated. Despite advances in medical devices and longer-acting insulin, there is still no robust therapy to substitute and protect beta-cells that are lost in T1DM. Attempts to refrain from the autoimmune attack have failed to achieve glycemic control in patients highlighting the necessity for a paradigm shift in T1DM treatment. Paradoxically, beta-cells are present in T1DM patients indicating a disturbed equilibrium between the immune attack and beta-cell regeneration reminiscent of unresolved wound healing that under normal circumstances progression towards an anti-inflammatory milieu promotes regeneration. Thus, the ultimate T1DM therapy should concomitantly restore immune self-tolerance and replenish the beta-cell mass similar to wound healing. Recently the agonistic activation of the nuclear receptor LRH-1/NR5A2 was shown to induce immune self-tolerance, increase beta-cell survival and promote regeneration through a mechanism of alpha-to-beta cell phenotypic switch. This trans-regeneration process appears to be facilitated by a pancreatic anti-inflammatory environment induced by LRH-1/NR5A2 activation. Herein, we review the literature on the role of LRH1/NR5A2 in immunity and islet physiology and propose that a cross-talk between these cellular compartments is mandatory to achieve therapeutic benefits.

Pharmacological LRH-1/Nr5a2 inhibition limits pro-inflammatory cytokine production in macrophages and associated experimental hepatitis

Liver receptor homolog-1 (LRH-1, Nr5a2) is an orphan nuclear receptor mainly expressed in tissues of endodermal origin, where its physiological role has been extensively studied. LRH-1 has been implicated in liver cell differentiation and proliferation, as well as glucose, lipid, and bile acid metabolism. In addition, increasing evidence highlights its role in immunoregulatory processes via glucocorticoid synthesis in the intestinal epithelium. Although the direct function of LRH-1 in immune cells is fairly elucidated, a role of LRH-1 in the regulation of macrophage differentiation has been recently reported. In this study, we aimed to investigate the role of LRH-1 in the regulation of pro-inflammatory cytokine production in macrophages. Our data demonstrate that pharmacological inhibition, along with LRH-1 knockdown, significantly reduced the lipopolysaccharide (LPS)-induced production of pro-inflammatory cytokines in the macrophage line RAW 264.7 cells, as well as in primary murine macrophages. This inhibitory effect was found to be independent of defects of LRH-1-regulated cell proliferation or toxic effects of the LRH-1 inhibitors. In contrast, LRH-1 inhibition reduced the mitochondrial ATP production and metabolism of macrophages through downregulation of the LRH-1 targets glucokinase and glutminase-2, and thus impairing the LPS-induced macrophage activation. Interestingly, in vivo pharmacological inhibition of LRH-1 also resulted in reduced tumor necrosis factor (TNF) production and associated decreased liver damage in a macrophage- and TNF-dependent mouse model of hepatitis. Noteworthy, despite hepatocytes expressing high levels of LRH-1, pharmacological inhibition of LRH-1 per se did not cause any obvious liver damage. Therefore, this study proposes LRH-1 as an emerging therapeutic target in the treatment of inflammatory disorders, especially where macrophages and cytokines critically decide the extent of inflammation.

Extra-Adrenal Glucocorticoid Synthesis in the Intestinal Mucosa: Between Immune Homeostasis and Immune Escape

Glucocorticoids (GCs) are steroid hormones predominantly produced in the adrenal glands in response to physiological cues and stress. Adrenal GCs mediate potent anti-inflammatory and immunosuppressive functions. Accumulating evidence in the past two decades has demonstrated other extra-adrenal organs and tissues capable of synthesizing GCs. This review discusses the role and regulation of GC synthesis in the intestinal epithelium in the regulation of normal immune homeostasis, inflammatory diseases of the intestinal mucosa, and the development of intestinal tumors.

A new class of protein biomarkers based on subcellular distribution: application to a mouse liver cancer model

To-date, most proteomic studies aimed at discovering tissue-based cancer biomarkers have compared the quantity of selected proteins between case and control groups. However, proteins generally function in association with other proteins to form modules localized in particular subcellular compartments in specialized cell types and tissues. Sub-cellular mislocalization of proteins has in fact been detected as a key feature in a variety of cancer cells. Here, we describe a strategy for tissue-biomarker detection based on a mitochondrial fold enrichment (mtFE) score, which is sensitive to protein abundance changes as well as changes in subcellular distribution between mitochondria and cytosol. The mtFE score integrates protein abundance data from total cellular lysates and mitochondria-enriched fractions, and provides novel information for the classification of cancer samples that is not necessarily apparent from conventional abundance measurements alone. We apply this new strategy to a panel of wild-type and mutant mice with a liver-specific gene deletion of Liver receptor homolog 1 (Lrh-1^hep−/−), with both lines containing control individuals as well as individuals with liver cancer induced by diethylnitrosamine (DEN). Lrh-1 gene deletion attenuates cancer cell metabolism in hepatocytes through mitochondrial glutamine processing. We show that proteome changes based on mtFE scores outperform protein abundance measurements in discriminating DEN-induced liver cancer from healthy liver tissue, and are uniquely robust against genetic perturbation. We validate the capacity of selected proteins with informative mtFE scores to indicate hepatic malignant changes in two independent mouse models of hepatocellular carcinoma (HCC), thus demonstrating the robustness of this new approach to biomarker research. Overall, the method provides a novel, sensitive approach to cancer biomarker discovery that considers contextual information of tested proteins.

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.

A phenotypic Caenorhabditis elegans screen identifies a selective suppressor of antipsychotic-induced hyperphagia

Antipsychotic (AP) drugs are used to treat psychiatric disorders but are associated with significant weight gain and metabolic disease. Increased food intake (hyperphagia) appears to be a driving force by which APs induce weight gain but the mechanisms are poorly understood. Here we report that administration of APs to C. elegans induces hyperphagia by a mechanism that is genetically distinct from basal food intake. We exploit this finding to screen for adjuvant drugs that suppress AP-induced hyperphagia in C. elegans and mice. In mice AP-induced hyperphagia is associated with a unique hypothalamic gene expression signature that is abrogated by adjuvant drug treatment. Genetic analysis of this signature using C. elegans identifies two transcription factors, nhr-25/Nr5a2 and nfyb-1/NFYB to be required for AP-induced hyperphagia. Our study reveals that AP-induced hyperphagia can be selectively suppressed without affecting basal food intake allowing for novel drug discovery strategies to combat AP-induced metabolic side effects.

C2H2-Type Zinc Finger Proteins: Evolutionarily Old and New Partners of the Nuclear Hormone Receptors

Nuclear hormone receptors (NRs) are evolutionarily conserved ligand-dependent transcription factors. They are essential for human life, mediating the actions of lipophilic molecules, such as steroid hormones and metabolites of fatty acid, cholesterol, and external toxic compounds. The C2H2-type zinc finger proteins (ZNFs) form the largest family of the transcription factors in humans and are characterized by multiple, tandemly arranged zinc fingers. Many of the C2H2-type ZNFs are conserved throughout evolution, suggesting their involvement in preserved biological activities, such as general transcriptional regulation and development/differentiation of organs/tissues observed in the early embryonic phase. However, some C2H2-type ZNFs, such as those with the Krüppel-associated box (KRAB) domain, appeared relatively late in evolution and have significantly increased family members in mammals including humans, possibly modulating their complicated transcriptional network and/or supporting the morphological development/functions specific to them. Such evolutional characteristics of the C2H2-type ZNFs indicate that these molecules influence the NR functions conserved through evolution, whereas some also adjust them to meet with specific needs of higher organisms. We review the interaction between NRs and C2H2-type ZNFs by focusing on some of the latter molecules.

Development of Hybrid Phospholipid Mimics as Effective Agonists for Liver Receptor Homologue-1

The orphan nuclear receptor Liver Receptor Homologue-1 (LRH-1) is an emerging drug target for metabolic disorders. The most effective known LRH-1 modulators are phospholipids or synthetic hexahydropentalene compounds. While both classes have micromolar efficacy, they target different portions of the ligand binding pocket and activate LRH-1 through different mechanisms. Guided by crystallographic data, we combined aspects of both ligand classes into a single scaffold, resulting in the most potent and efficacious LRH-1 agonists to date.

Signaling through non-membrane nuclear phosphoinositide binding proteins in human health and disease

Phosphoinositide membrane signaling is critical for normal physiology, playing well-known roles in diverse human pathologies. The basic mechanisms governing phosphoinositide signaling within the nucleus, however, have remained deeply enigmatic owing to their presence outside the nuclear membranes. Over 40% of nuclear phosphoinositides can exist in this non-membrane state, held soluble in the nucleoplasm by nuclear proteins that remain largely unidentified. Recently, two nuclear proteins responsible for solubilizing phosphoinositides were identified, steroidogenic factor-1 (SF-1; NR5A1) and liver receptor homolog-1 (LRH-1; NR5A2), along with two enzymes that directly remodel these phosphoinositide/protein complexes, phosphatase and tensin homolog (PTEN; MMAC) and inositol polyphosphate multikinase (IPMK; ipk2). These new footholds now permit the assignment of physiological functions for nuclear phosphoinositides in human diseases, such as endometriosis, nonalcoholic fatty liver disease/steatohepatitis, glioblastoma, and hepatocellular carcinoma. The unique nature of nuclear phosphoinositide signaling affords extraordinary clinical opportunities for new biomarkers, diagnostics, and therapeutics. Thus, phosphoinositide biology within the nucleus may represent the next generation of low-hanging fruit for new drugs, not unlike what has occurred for membrane phosphatidylinositol 3-kinase drug development. This review connects recent basic science discoveries in nuclear phosphoinositide signaling to clinical pathologies, with the hope of inspiring development of new therapies.

Liver receptor homologue 1, a novel prognostic marker in colon cancer patients

Liver receptor homologue 1 (LRH-1) is an orphan nuclear receptor that is highly expressed in a variety of cancer tissues, promotes tumor cell proliferation and metastasis, and is involved in the tumor cell cycle and apoptosis. The aim of the present study was to assess the association between the expression of LRH-1 and the prognosis of patients with colon cancer. Immunohistochemistry was used to detect the expression of LRH1 in 128 cases of colon cancer and adjacent tissues. The 5-year survival rate was obtained from telephone follow-up data, outpatient review and through access to medical records. Positive expression of LRH-1 was found in 108/128 colon cancer samples, compared with 17/128 normal tissues. Statistical analysis showed that positive LRH-1 expression was significantly associated with clinical pathological stage, depth of invasion and lymph node metastasis. The overall survival (OS) rate of patients with positive LRH-1 expression was significantly lower than that of patients with low expression. Multivariate analysis showed that LRH-1 expression could be used as an independent predictor of OS. In conclusion, the present findings suggest that LRH-1 may serve an important role in the development and progression of colon cancer, with potential value as a prognostic molecular marker that could be used to assist in the diagnosis and evaluation of colon cancer. LRH-1 may become a target for novel therapies for patients with colon cancer.

Transcriptional regulation by NR5A2 links differentiation and inflammation in the pancreas

Chronic inflammation increases the risk of several cancer types. The current notion is that the control of inflammatory responses relies on transcriptional networks distinct from those involved in cell differentiation ^1–3. The orphan nuclear receptor NR5A2 participates in a wide variety of processes including cholesterol and glucose metabolism in the liver, resolution of ER stress, intestinal glucocorticoid production, pancreatic development, and acinar differentiation ^4–8. Single nucleotide polymorphisms (SNPs) in the vicinity of NR5A2 have been associated with the risk of pancreatic adenocarcinoma (PDAC) through genome wide association studies ^9,10. In mice, Nr5a2 heterozygosity sensitizes the pancreas to damage, impairs regeneration, and cooperates with mutant KRas in tumor progression ¹¹. Through global transcriptomic analysis, we describe here an epithelial cell-autonomous basal pre-inflammatory state in the pancreas of Nr5a2^+/− mice that is reminiscent of early stages of pancreatitis-induced inflammation and is conserved in histologically normal human pancreata with reduced NR5A2 mRNA expression. In Nr5a2^+/− mice, Nr5a2 undergoes a dramatic transcriptional switch relocating from differentiation-specific to inflammatory genes thereby promoting AP-1-dependent gene transcription. Pancreatic deletion of c-Jun rescues the pre-inflammatory phenotype, Nr5a2 binding to inflammatory gene promoters, and the defective regenerative response to damage. These findings support the notion that, in the pancreas, the same transcriptional networks involved in differentiation-specific functions suppress inflammatory programmes. These networks can be subverted to foster inflammation upon genetic or environmental constraints.

The Roles of SUMO in Metabolic Regulation

Protein modification with the small ubiquitin-related modifier (SUMO) can affect protein function, enzyme activity, protein-protein interactions, protein stability, protein targeting and cellular localization. SUMO influences the function and regulation of metabolic enzymes within pathways, and in some cases targets entire metabolic pathways by affecting the activity of transcription factors or by facilitating the translocation of entire metabolic pathways to subcellular compartments. SUMO modification is also a key component of nutrient- and metabolic-sensing mechanisms that regulate cellular metabolism. In addition to its established roles in maintaining metabolic homeostasis, there is increasing evidence that SUMO is a key factor in facilitating cellular stress responses through the regulation and/or adaptation of the most fundamental metabolic processes, including energy and nucleotide metabolism. This review focuses on the role of SUMO in cellular metabolism and metabolic disease.

Liver receptor homolog-1 regulates mouse superoxide dismutase 2

Liver receptor homolog-1 (LRH-1) is a nuclear receptor that plays an important role in the regulation of bile acid biosynthesis, cholesterol reverse transport, steroidogenesis, and exocrine pancreatic enzyme production. In the current study, previously published data from a genome wide analysis of LRH-1 binding in the liver were re-analyzed to identify new LRH-1 targets and propose new roles for LRH-1 in the liver. Superoxide dismutase 2 (Sod2) was identified, which contains putative LRH-1 binding sites in the proximal promoter. When hepatocytes were treated with the LRH-1 agonist RJW101, Sod2 expression was dramatically increased and reactive oxygen species (ROS) production, which was induced by a high concentration of palmitate, was significantly reduced. A LRH-1 binding site was mapped to -288/-283 in the Sod2 promoter, which increased Sod2 promoter activity in response to LRH-1 and its agonist. LRH-1 binding to this site was confirmed using a chromatin immunoprecipitation assay. These results suggest that Sod2 is a target gene of LRH-1, and that LRH-1 agonists can mediate a reduction in ROS production and oxidative stress driven by an excess of fatty acids, as exhibited in nonalcoholic fatty liver disease.

LRH-1 expression patterns in breast cancer tissues are associated with tumour aggressiveness

The significance and regulation of liver receptor homologue 1 (LRH-1, NR5A2), a tumour-promoting transcription factor in breast cancer cell lines, is unknown in clinical breast cancers. This study aims to determine LRH-1/NR5A2 expression in breast cancers and relationship with DNA methylation and tumour characteristics. In The Cancer Genome Atlas breast cancer cohort NR5A2 expression was positively associated with intragenic CpG island methylation (1.4-fold expression for fully methylated versus not fully methylated, p=0.01) and inversely associated with promoter CpG island methylation (0.6-fold expression for fully methylated versus not fully methylated, p=0.036). LRH-1 immunohistochemistry of 329 invasive carcinomas and ductal carcinoma in situ (DCIS) was performed. Densely punctate/coarsely granular nuclear reactivity was significantly associated with high tumour grade (p<0.005, p=0.033 in invasive carcinomas and DCIS respectively), negative estrogen receptor status (p=0.008, p=0.038 in overall cohort and invasive carcinomas, respectively), negative progesterone receptor status (p=0.003, p=0.013 in overall cohort and invasive carcinomas, respectively), HER2 amplification (overall cohort p=0.034) and non-luminal intrinsic subtype (p=0.018, p=0.038 in overall cohort and invasive carcinomas, respectively). These significant associations of LRH-1 protein expression with tumour phenotype suggest that LRH-1 is an important indicator of tumour biology in breast cancers and may be useful in risk stratification.

LRH-1-dependent programming of mitochondrial glutamine processing drives liver cancer

Xu et al. identify the nuclear receptor liver receptor homolog 1 (LRH-1) as a key regulator in the process of hepatic tumorigenesis through the coordination of a noncanonical glutamine pathway that is reliant on the mitochondrial and cytosolic transaminases glutamate pyruvate transaminase 2 (GPT2) and glutamate oxaloacetate transaminase 1 (GOT1), which fuel anabolic metabolism.

Various tumors develop addiction to glutamine to support uncontrolled cell proliferation. Here we identify the nuclear receptor liver receptor homolog 1 (LRH-1) as a key regulator in the process of hepatic tumorigenesis through the coordination of a noncanonical glutamine pathway that is reliant on the mitochondrial and cytosolic transaminases glutamate pyruvate transaminase 2 (GPT2) and glutamate oxaloacetate transaminase 1 (GOT1), which fuel anabolic metabolism. In particular, we show that gain and loss of function of hepatic LRH-1 modulate the expression and activity of mitochondrial glutaminase 2 (GLS2), the first and rate-limiting step of this pathway. Acute and chronic deletion of hepatic LRH-1 blunts the deamination of glutamine and reduces glutamine-dependent anaplerosis. The robust reduction in glutaminolysis and the limiting availability of α-ketoglutarate in turn inhibit mTORC1 signaling to eventually block cell growth and proliferation. Collectively, these studies highlight the importance of LRH-1 in coordinating glutamine-induced metabolism and signaling to promote hepatocellular carcinogenesis.

NR5A2 discovering compounds that block tumor growth in PDAC

Pancreatic cancers depend on driver molecules, oncogene proteins such as RAS. NR5A2 protein is a transcription factor and either activates or inhibits transcription through actions at hundreds of enhancers. It has unusual properties with effects appearing in multiple signaling networks. NR5A2 is a pluripotency reprogramming factor in the class nuclear receptor. Its controlling hormone is PIP3. Experiments suggest NR5A2 activation drives PDAC and inhibitors blunt cancer cell proliferation.

Downregulation of microRNA-30d promotes cell proliferation and invasion by targeting LRH-1 in colorectal carcinoma

The aberrant expression of miR-30d has been reported in several types of human malignancies. However, its biological function in colorectal cancer (CRC) remains largely unknown. In this study, we identified that miR-30d was significantly downregulated in CRC tissues compared to that observed in normal controls as detected by RT-qPCR analysis. Downregulation of miR-30d was significantly associated with aggressive clinicopathological parameters including tumor differentiation, invasive depth, TNM stage, lymph node metastasis, distant metastasis, and poor prognosis. Furthermore, functional analysis revealed that overexpression of miR-30d significantly inhibited cell proliferation, caused cell cycle arrest at the G0/G1 phase, suppressed cell migration and invasion, induced cell apoptosis in vitro, and decreased tumor growth in a xenograft mouse model. Bioinformatic analysis and dual-luciferase reporter assay revealed that liver receptor homologue-1 (LRH-1) is a direct target of miR-30d in CRC cells. Rescue assay showed that LRH-1 overexpression could restore the inhibitory effect of miR-30d on CRC cells. In addition, miR-30d overexpression suppressed the activation of key components of the Wnt/β-catenin signaling pathway, β-catenin, c-Myc and cyclin D1, which contributed to the inhibition of CRC development. Thus, our findings suggest that miR-30d functions as a tumor suppressor against CRC development and miR-30d/LRH-1/Wnt signaling may be novel potential targets for CRC treatment.

Liver receptor homolog-1 (NR5a2) regulates CD95/Fas ligand transcription and associated T-cell effector functions

CD95/Fas ligand (FasL) is a cell death-promoting member of the tumor necrosis factor family with important functions in the regulation of T-cell homeostasis and cytotoxicity. In T cells, FasL expression is tightly regulated on a transcriptional level involving a complex set of different transcription factors. The orphan nuclear receptor liver receptor homolog-1 (LRH-1/NR5a2) is involved in the regulation of development, lipid metabolism and proliferation and is predominantly expressed in epithelial tissues. However, its expression in T lymphocytes has never been reported so far. Based on in silico analysis, we identified potential LRH-1 binding sites within the FASLG promoter. Here, we report that LRH-1 is expressed in primary and secondary lymphatic tissues, as well as in CD4⁺ and CD8⁺ T cells. LRH-1 directly binds to its binding sites in the FASLG promoter, and thereby drives FASLG promoter activity. Mutations in the LRH-1 binding sites reduce FASLG promoter activity. Pharmacological inhibition of LRH-1 decreases activation-induced FasL mRNA expression, as well as FasL-mediated activation-induced T-cell apoptosis and T-cell cytotoxicity. In a mouse model of Concanavalin A-induced and FasL-mediated hepatitis pharmacological inhibition of LRH-1 resulted in decreased hepatic FasL expression and a significant reduction of liver damage. In summary, these data show for the first time LRH-1 expression in T cells, its role in FASLG transcription and the potential of pharmacological inhibition of LRH-1 in the treatment of FasL-mediated immunopathologies.

Impaired SUMOylation of nuclear receptor LRH-1 promotes nonalcoholic fatty liver disease

Hepatic steatosis is caused by metabolic imbalances that could be explained in part by an increase in de novo lipogenesis that results from increased sterol element binding protein 1 (SREBP-1) activity. The nuclear receptor liver receptor homolog 1 (LRH-1) is an important regulator of intermediary metabolism in the liver, but its role in regulating lipogenesis is not well understood. Here, we have assessed the contribution of LRH-1 SUMOylation to the development of nonalcoholic fatty liver disease (NAFLD). Mice expressing a SUMOylation-defective mutant of LRH-1 (LRH-1 K289R mice) developed NAFLD and early signs of nonalcoholic steatohepatitis (NASH) when challenged with a lipogenic, high-fat, high-sucrose diet. Moreover, we observed that the LRH-1 K289R mutation induced the expression of oxysterol binding protein-like 3 (OSBPL3), enhanced SREBP-1 processing, and promoted de novo lipogenesis. Mechanistically, we demonstrated that ectopic expression of OSBPL3 facilitates SREBP-1 processing in WT mice, while silencing hepatic Osbpl3 reverses the lipogenic phenotype of LRH-1 K289R mice. These findings suggest that compromised SUMOylation of LRH-1 promotes the development of NAFLD under lipogenic conditions through regulation of OSBPL3.

PPAR-pan activation induces hepatic oxidative stress and lipidomic remodelling

The peroxisome proliferator-activated receptors (PPARs) are ligand activated nuclear receptors that regulate cellular homoeostasis and metabolism. PPARs control the expression of genes involved in fatty-acid and lipid metabolism. Despite evidence showing beneficial effects of their activation in the treatment of metabolic diseases, particularly dyslipidaemias and type 2 diabetes, PPAR agonists have also been associated with a variety of side effects and adverse pathological changes. Agonists have been developed that simultaneously activate the three PPAR receptors (PPARα, γ and δ) in the hope that the beneficial effects can be harnessed while avoiding some of the negative side effects. In this study, the hepatic effects of a discontinued PPAR-pan agonist (a triple agonist of PPAR-α, -γ, and -δ), was investigated after dietary treatment of male Sprague-Dawley (SD) rats. The agonist induced liver enlargement in conjunction with metabolomic and lipidomic remodelling. Increased concentrations of several metabolites related to processes of oxidation, such as oxo-methionine, methyl-cytosine and adenosyl-methionine indicated increased stress and immune status. These changes are reflected in lipidomic changes, and increased energy demands as determined by free fatty acid (decreased 18:3 n-3, 20:5 n-3 and increased ratios of n-6/n-3 fatty acids) triacylglycerol, phospholipid (decreased and increased bulk changes respectively) and eicosanoid content (increases in PGB2 and 15-deoxy PGJ2). We conclude that the investigated PPAR agonist, GW625019, induces liver enlargement, accompanied by lipidomic remodelling, oxidative stress and increases in several pro-inflammatory eicosanoids. This suggests that such pathways should be monitored in the drug development process and also outline how PPAR agonists induce liver proliferation.