Orphan Nuclear Hormone Receptor Research Articles

Nur77 Mediates Anaphylaxis by Regulating miR-21a.

Nur77 belongs to the NR4A subfamily of orphan nuclear hormone receptors. It has been shown to play important roles in metabolism, cancer progression, cellular differentiation, and the regulation of immune process. However, there has yet to be research reporting on the role of Nur77 in allergic inflammations such as anaphylaxis. This study aimed to identify molecules that could mediate allergic inflammations. To this end, we performed RNA sequencing analysis employing bone marrow-derived mast cells (BMMCs). Antigen (DNP-HSA) stimulation increased the expression levels of transcription factors such as Nr4a3 (NOR1), Nr4a1 (Nur77), and Nr4a2 (Nurr1). We focused our study on Nur77. Antigen stimulation increased the expression of Nur77 in a time- and dose-dependent manner in rat basophilic leukemia cells (RBL2H3). The downregulation of Nur77 prevented both antigen-induced increase in β-hexosaminidase activity as well as hallmarks of allergic reactions such as HDAC3, COX2, and MCP1 in RBL2H3 cells. Nur77 was necessary for both passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA). TargetScan analysis predicted that miR-21a would be a negative regulator of Nur77. miR-21a mimic negatively regulated PCA and PSA by inhibiting the hallmarks of allergic reactions. ChIP assays showed that c-JUN could bind to the promoter sequences of Nur77. Antigen stimulation increased the expression of c-JUN in RBL2H3 cells. Altogether, our findings demonstrate the regulatory role played by Nur77-miR-21a loop in allergic inflammations such as anaphylaxis, making this the first report to present the role played by Nur77 in an allergic inflammation. Our results suggest that Nur77 and miR-21 might serve as targets for developing anti-allergy drugs.

Seven-up acts in neuroblasts to specify adult central complex neuron identity and initiate neuroblast decommissioning.

An unanswered question in neurobiology is how are diverse neuron cell types generated from a small number of neural stem cells? In the Drosophila larval central brain, there are eight bilateral Type 2 neuroblast (T2NB) lineages that express a suite of early temporal factors followed by a different set of late temporal factors and generate the majority of the central complex (CX) neurons. The early-to-late switch is triggered by the orphan nuclear hormone receptor Seven-up (Svp), yet little is known about how this Svp-dependent switch is involved in specifying CX neuron identities. Here, we: (1) birth date the CX neurons P-EN and P-FN (early and late, respectively); (2) show that Svp is transiently expressed in all early T2NBs; and (3) show that loss of Svp expands the population of early born P-EN neurons at the expense of late born P-FN neurons. Furthermore, in the absence of Svp, T2NBs fail decommissioning and abnormally extend their lineage into week-old adults. We conclude that Svp is required to specify CX neuron identity, as well as to initiate T2NB decommissioning.

The pro-inflammatory phenotype of human macrophages is restricted by the activity of the orphan nuclear receptor Nurr1

Abstract The nuclear receptor related 1 protein (Nurr1) is a member of the orphan nuclear hormone receptor family whose expression has been associated with several inflammatory diseases. Macrophages are key regulators of the inflammatory processes, yet information about the role of Nurr1 in human macrophages is limited. In the present study we examined the expression and activity of Nurr1 in steady state and activated human monocyte-derived macrophages. Pro- and anti-inflammatory macrophages were derived in vitro by culture of blood monocytes with the hematopoietic cytokines GM-CSF and M-CSF, respectively. Nurr1 expression was predominant in macrophages with a pro-inflammatory phenotype. Accordingly, its expression was induced by a variety of inflammatory stimuli such as TLR-2, -3 and -4 ligands, TNF, IFN-β, and IL-4. Pro-inflammatory macrophages exposed to the Nurr1 agonist C-DIM12 decreased their production of IL-1β, IL-6, and reactive oxygen species. Conversely, Nurr1 deficient macrophages produced enhanced levels of IL-6. Mechanistically, Nurr1 agonists partially abrogated the activation of the NF-κB signaling pathway in pro-inflammatory macrophages exposed to LPS, rendering cells with a lower rate of NF-κB p65 nuclear translocation. These results suggest that Nurr1 expression is linked with the pro-inflammatory phenotype of human macrophages where it may constitute a brake to attenuate the synthesis of inflammatory mediators. Supported by grants from Secretaria de Educación Pública-Consejo Nacional de Ciencia y Tecnología (SEP-CONACYT, #A1-S-9430)

Nr4a nuclear receptors: markers and modulators of antigen receptor signaling.

Nr4a1-3 encode a small family of orphan nuclear hormone receptors with transcriptional activity. Their expression reflects both acute and chronic antigen-receptor signaling in T and B-cells, and they have been implicated in critical aspects of lymphocyte development, tolerance, and function. These include roles in regulatory T-cell (Treg), thymic-negative selection, humoral responses, anergy, and exhaustion. Here, we review recent advances in this field such as functional roles in B-cells, transcriptional targets, and mechanism of action. We highlight recurrent themes, including integration of antigen-receptor signaling with costimulatory input, as well as unanswered questions and translational applications of this work.

COUP-TFII in Kidneys, from Embryos to Sick Adults.

Chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) is an orphan nuclear hormone receptor of unknown ligands. This molecule has two interesting features: (1) it is a developmental gene, and (2) it is a potential hormone receptor. Here, we describe the possible roles of COUP-TFII in the organogenesis of the kidneys and protection from adult renal diseases, primarily in mouse models. COUP-TFII is highly expressed in embryos, including primordial kidneys, and is essential for the formation of metanephric mesenchyme and the survival of renal precursor cells. Although the expression levels of COUP-TFII are low and its functions are unknown in healthy adults, it serves as a reno-protectant molecule against acute kidney injury. These are good examples of how developmental genes exhibit novel functions in the etiology of adult diseases. We also discuss the ongoing research on the roles of COUP-TFII in podocyte development and diabetic kidney disease. In addition, the identification of potential ligands suggests that COUP-TFII might be a novel therapeutic target for renal diseases in the future.

Genetic variation of macronutrient tolerance in Drosophila melanogaster

Carbohydrates, proteins and lipids are essential nutrients to all animals; however, closely related species, populations, and individuals can display dramatic variation in diet. Here we explore the variation in macronutrient tolerance in Drosophila melanogaster using the Drosophila genetic reference panel, a collection of ~200 strains derived from a single natural population. Our study demonstrates that D. melanogaster, often considered a “dietary generalist”, displays marked genetic variation in survival on different diets, notably on high-sugar diet. Our genetic analysis and functional validation identify several regulators of macronutrient tolerance, including CG10960/GLUT8, Pkn and Eip75B. We also demonstrate a role for the JNK pathway in sugar tolerance and de novo lipogenesis. Finally, we report a role for tailless, a conserved orphan nuclear hormone receptor, in regulating sugar metabolism via insulin-like peptide secretion and sugar-responsive CCHamide-2 expression. Our study provides support for the use of nutrigenomics in the development of personalized nutrition.

Abstract 11998: The microRNA-378 and Estrogen-Related Receptor Gamma Axis Regulates Metabolic Inflammation and Lipoprotein Metabolism: A Potential Therapeutic Target for Atherosclerosis

MicroRNAs (miRNAs) are non-coding small RNAs that interact with their targeted mRNAs, resulting in decay or translational repression of the targeted mRNAs. The estrogen-related receptor (ERR)γ is an orphan nuclear hormone receptor. MiRNAs and ERRγ play pivotal roles in the pathophysiological conditions of metabolic diseases. The objective of this study is to determine the impact of miR-378a and its targeted gene ERRγ in metabolic inflammation and HDL metabolism, and explore the therapeutic potential of antigomic miRNA in atherosclerosis. Bioinformatics analysis of hepatic miRNA sequencing profile from mice fed a lipogenic diet (high-fructose) revealed that miR-378a was upregulated and served as a hub in a regulatory network that collaboratively targets multiple metabolic signal molecules in energy metabolism, mitochondrial fatty acid β-oxidation (FAO), and lipoprotein metabolism. Specifically, the upregulated miR-378a induced by fructose suppressed expression of ERRγ and genes involved in FAO (e.g., PPARα, CPT1α and ACOX1). In contrast, genetic depletion of miR-378a (miR-378aKO) significantly enhanced ERRγ expression, ameliorated mitochondrial oxidative stress and metabolic inflammation. Furthermore, miR-378aKO markedly stimulated expression of genes involved in HDL metabolism, including LXRα, ABCA1 and aopA4, leading to the increase of HDL-cholesterol and decrease of LDL-cholesterol in blood circulation. An in vivo VLDL secretion assay further revealed that miR-378aKO inhibited biogenesis and secretion of VLDL from the KO mouse liver, suggesting an improvement of atherogenic status in the absence of miR-378a. More importantly, treated the fructose-fed mice with nanoparticles carrying antagomir against miR-378a successfully reduced hepatic miR-378a expression, which was associated with significant restoration of ERRγ signaling and the associated mitochondrial FAO and HDL metabolism, indicated by the increased gene expression of PPARα, CPT1α and ACOX-1 as well as LXRα and apoA4, in the treated mice. Conclusion: These data indicate that manipulating miR-378a level can restore ERRγ signaling, improve FAO and lipoprotein metabolism. This novel finding may lend support to the therapeutic strategy of atherosclerosis.

1-deoxysphingolipids bind to COUP-TF to modulate lymphatic and cardiac cell development.

Identification of physiological modulators of nuclear hormone receptor (NHR) activity is paramount for understanding the link between metabolism and transcriptional networks that orchestrate development and cellular physiology. Using libraries of metabolic enzymes alongside their substrates and products, we identify 1-deoxysphingosines as modulators of the activity of NR2F1 and 2 (COUP-TFs), which are orphan NHRs that are critical for development of the nervous system, heart, veins, and lymphatic vessels. We show that these non-canonical alanine-based sphingolipids bind to the NR2F1/2 ligand-binding domains (LBDs) and modulate their transcriptional activity in cell-based assays at physiological concentrations. Furthermore, inhibition of sphingolipid biosynthesis phenocopies NR2F1/2 deficiency in endothelium and cardiomyocytes, and increases in 1-deoxysphingosine levels activate NR2F1/2-dependent differentiation programs. Our findings suggest that 1-deoxysphingosines are physiological regulators of NR2F1/2-mediated transcription.

The Role of Histone Deacetylase 3 Complex in Nuclear Hormone Receptor Action.

Nuclear hormone receptors (NRs) regulate transcription of the target genes in a ligand-dependent manner in either a positive or negative direction, depending on the case. Deacetylation of histone tails is associated with transcriptional repression. A nuclear receptor corepressor (N-CoR) and a silencing mediator for retinoid and thyroid hormone receptors (SMRT) are the main corepressors responsible for gene suppression mediated by NRs. Among numerous histone deacetylases (HDACs), HDAC3 is the core component of the N-CoR/SMRT complex, and plays a central role in NR-dependent repression. Here, the roles of HDAC3 in ligand-independent repression, gene repression by orphan NRs, NRs antagonist action, ligand-induced repression, and the activation of a transcriptional coactivator are reviewed. In addition, some perspectives regarding the non-canonical mechanisms of HDAC3 action are discussed.

Nematode nuclear receptors as integrators of sensory information

More than 20 years ago, the sequencing of the genome of the nematode Caenorhabditis elegans uncovered a still unparalleled abundance of C4-zinc finger orphan nuclear hormone receptors, encoded by 267 different nhr genes.1,2 Only less than 20 of them are conserved throughout the animal kingdom; all the remaining genes are the results of an expansion of the HNF4-subtype of nuclear receptors.3,4 Strikingly, even though most of the receptors contain predicted ligand binding domains, no ligand has since been identified for any of the non-conserved, C.elegans-expanded nhr genes. Based on an analysis of more than 100 nematode genome sequences, as well as the mining of recently established nervous system-wide gene expression patterns, we propose here that nhr family expansion is a manifestation of adaptation of free-living nematodes to complex sensory environments and that NHR proteins may function as sensory receptors for external or internal sensory cues to modulate the animal's sensory responses to environmental cues as well as its internal metabolic state.

5,6,7,8-Tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivative attenuates lupus nephritis with less effect to thymocyte development.

Retinoic‑acid‑receptor‑related orphan nuclear hormone receptor gamma t (RORγt), a critical transcriptional factor of Th17 cells, is a potential therapeutic target for Th17-mediated autoimmune diseases. In addition, RORγt is essential for thymocyte survival and lymph node development, and RORγt inhibition or deficiency causes abnormal thymocyte development, thymus lymphoma, and lymph node defect. Recent study demonstrated that specific regulation of Th17 differentiation related to the hinge region of RORγt. In this research, we investigated the effect of RORγt inhibitor, 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivative (TTP), in the therapy of lupus nephritis and its safety on thymocyte development. We demonstrated that TTP repressed the development of Th17 cells and ameliorated the autoimmune disease manifestation in the pristane-induced lupus nephritis mice model. The treatment of TTP in the mice did not interfere with thymocyte development, including total thymocyte number and proportion of CD4+CD8+ double-positive populations in the thymus, and had no substantial effects on the pathogenesis of thymoma. The TTP had a stronger affinity with full-length RORγt protein compared with the truncated RORγt LBD region via surface plasmon resonance, which indicated TTP binding to RORγt beyond LBD region. Molecular docking computation showed that the best binding pocket of TTP to RORγt is located in the hinge region of RORγt. In summary, as a RORγt inhibitor, TTP had a potential to develop the clinical medicine for treating Th17-mediated autoimmune diseases with low safety risk for thymocyte development.

Investigation of Epigenetic Control of DAX-1 Expression in Human Cell Lines

Dosage-Sensitive Sex Reversal, Adrenal Hypoplasia Congenita, Critical Region on the X chromosome, gene 1 (DAX-1 or NR0B1) is an orphan nuclear hormone receptor implicated in Adrenal Hypoplasia Congenita (AHC) and Dosage Sensitive Sex Reversal (DSS). In both instances, DAX-1 plays a key role in growth and development by modulating hormone function. In DSS, mutations on the X-chromosome lead to duplication of the region containing DAX-1, resulting in sex reversal, and in AHC, mutations in the DAX-1 gene diminish development of adrenal tissue which leads to a reduction in adrenal hormone production. Expressed predominantly in tissues such as the testes, ovaries, breast, adrenal cortex, and lung, DAX-1 may serve as an indicator of aberrant growth. Here we hypothesize that DAX-1 is epigenetically regulated, specifically in cancer cells, thereby reducing its expression. We surveyed various human cancer cells in order to determine whether inhibiting DNA methylating enzymes released epigenetic control of the DAX-1 gene, resulting in an increase in expression. By implementing molecular techniques, such as bisulfite sequencing, we determined the precise methylation sites in the DAX-1 gene. Additionally, we carried out methylation specific restriction enzyme analysis to differentiate degrees of methylation between lung, breast, liver, cervical, and adrenal carcinoma cell lines. Following confirmation of the precise methylation sites, we utilized chromatin immunoprecipitation (ChIP) in order to identify the modifying proteins present on the DAX-1 CpG islands. In conjunction with these experimental techniques, we implemented a bioinformatics approach to analyze methylation in the promoter region of the DAX-1 gene across tissue sample data acquired from The Cancer Genome Atlas Program. The results of this research could lead to a translational application of understanding where this orphan NHR fits into the development and progression of cancer. As a quickly growing field, cancer epigenetics is a key player in the ongoing pursuit for identifying biomarkers that may be pertinent in future therapeutic applications.

Gremlin-1 augments the oestrogen-related receptor \u03b1 signalling through EGFR activation: implications for the progression of breast cancer

BackgroundGremlin-1 (GREM1), one of the bone morphogenetic protein antagonists, is involved in organogenesis, tissue differentiation and kidney development. However, the role of GREM1 in cancer progression and its underlying mechanisms remain poorly understood.MethodsThe role of GREM1 in breast cancer progression was assessed by measuring cell viability, colony formation, 3D tumour spheroid formation/invasion and xenograft tumour formation. Chromatin immunoprecipitation, a luciferase reporter assay and flow cytometry were performed to investigate the molecular events in which GREM1 is involved.ResultsGREM1 expression was elevated in breast cancer cells and tissues obtained from breast cancer patients. Its overexpression was associated with poor prognosis in breast cancer patients, especially those with oestrogen receptor (ER)-negative tumours. GREM1 knockdown inhibited the proliferation of breast cancer cells and xenograft mammary tumour growth, while its overexpression enhanced their viability, growth and invasiveness. Oestrogen-related receptor α (ERRα), an orphan nuclear hormone receptor, directly interacted with the GREM1 promoter and increased the expression of GREM1. GREM1 also enhanced the promoter activity of ESRRA encoding ERRα, comprising a positive feedback loop. Notably, GREM1 bound to and activated EGFR, a well-known upstream regulator of ERRα.ConclusionsOur study suggests that the GREM1–ERRα axis can serve as a potential therapeutic target in the management of cancer, especially ER-negative tumour.

FSTL-1 Attenuation Causes Spontaneous Smoke-Resistant Pulmonary Emphysema.

Rationale: The role of FSTL-1 (follistatin-like 1) in lung homeostasis is unknown.Objectives: We aimed to define the impact of FSTL-1 attenuation on lung structure and function and to identify FSTL-1-regulated transcriptional pathways in the lung. Further, we aimed to analyze the association of FSTL-1 SNPs with lung disease.Methods: FSTL-1 hypomorphic (FSTL-1 Hypo) mice underwent lung morphometry, pulmonary function testing, and micro-computed tomography. Fstl1 expression was determined in wild-type lung cell populations from three independent research groups. RNA sequencing of wild-type and FSTL-1 Hypo mice identified FSTL-1-regulated gene expression, followed by validation and mechanistic in vitro examination. FSTL1 SNP analysis was performed in the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) cohort.Measurements and Main Results: FSTL-1 Hypo mice developed spontaneous emphysema, independent of smoke exposure. Fstl1 is highly expressed in the lung by mesenchymal and endothelial cells but not immune cells. RNA sequencing of whole lung identified 33 FSTL-1-regulated genes, including Nr4a1, an orphan nuclear hormone receptor that negatively regulates NF-κB (nuclear factor-κB) signaling. In vitro, recombinant FSTL-1 treatment of macrophages attenuated NF-κB p65 phosphorylation in an Nr4a1-dependent manner. Within the COPDGene cohort, several SNPs in the FSTL1 region corresponded to chronic obstructive pulmonary disease and lung function.Conclusions: This work identifies a novel role for FSTL-1 protecting against emphysema development independent of smoke exposure. This FSTL-1-deficient emphysema implicates regulation of immune tolerance in lung macrophages through Nr4a1. Further study of the mechanisms involving FSTL-1 in lung homeostasis, immune regulation, and NF-κB signaling may provide additional insight into the pathophysiology of emphysema and inflammatory lung diseases.

Disruption of hepatic small heterodimer partner induces dissociation of steatosis and inflammation in experimental nonalcoholic steatohepatitis

Disruption of hepatic small heterodimer partner induces dissociation of steatosis and inflammation in experimental nonalcoholic steatohepatitis

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.

Development of the First Low Nanomolar Liver Receptor Homolog-1 Agonist through Structure-guided Design.

As a key regulator of metabolism and inflammation, the orphan nuclear hormone receptor, liver receptor homolog-1 (LRH-1), has potential as a therapeutic target for diabetes, nonalcoholic fatty liver disease, and inflammatory bowel diseases (IBD). Discovery of LRH-1 modulators has been difficult, in part due to the tendency for synthetic compounds to bind unpredictably within the lipophilic binding pocket. Using a structure-guided approach, we exploited a newly discovered polar interaction to lock agonists in a consistent orientation. This enabled the discovery of the first low nanomolar LRH-1 agonist, one hundred times more potent than the best previous modulator. We elucidate a novel mechanism of action that relies upon specific polar interactions deep in the LRH-1 binding pocket. In an organoid model of IBD, the new agonist increases expression of LRH-1-controlled steroidogenic genes and promotes anti-inflammatory gene expression changes. These studies constitute major progress in developing LRH-1 modulators with potential clinical utility.

2190-P: Sex-Based Differences in Nr4a1 Beta-Cell Activity

The orphan nuclear hormone receptor Nr4a1 plays a critical role in maintaining and expanding functional beta cell mass. Overexpression of Nr4a1 is sufficient to induce beta cell proliferation in primary beta cells by upregulating cell cycle progression, while maintaining glucose-stimulated insulin secretion. Full body deletion of Nr4a1 results in decreased beta cell mass, while resulting in modified fuel utilization in liver and muscle. Knock down of Nr4a1 decreases glycolytic and TCA cycle gene expression, impairs mitochondrial respiration, decreases cellular ATP levels, and ultimately decreases glucose-stimulated insulin secretion. While Nr4a1 is currently considered an orphaned nuclear hormone receptor, recent findings suggest that unsaturated fatty acids may function as a ligand, and that exposure to these fatty acid’s changes Nr4a1 affinity for promoters of genes involved in fuel utilization. To determine the effect of Nr4a1 presence of absence in the beta cell, and the effect of fatty acid exposure, we developed a beta cell specific, inducible, Nr4a1 knock out mouse. Male and female mice, deficient for Nr4a1 beginning at 3 months of age, were fed a normal chow or high fat diet for an additional four months. Here we present data demonstrating a sex specific difference in phenotype. Male mice demonstrated improved glucose tolerance at four months of feeding, while female mice demonstrated impaired glucose tolerance as early as one month of feeding. Here we present data regarding differences in beta cell mass, glucose stimulated insulin secretion, as well as Nr4a1 DNA binding from in islets from male and female mice exposed to unsaturated and saturated fatty acids. These data begin to demonstrate the role of Nr4a1 in controlling gene expression as a function of nutrient exposure, as well as sex-based differences in Nr4a1 activity. Disclosure J.S. Tessem: None. J. Herring: None. C.J. Smith: None. M.C. Austin: None. A.G. Wynn: None. Funding American Diabetes Association (1-17-IBS-101 to J.S.T.)

SOCS3 ablation enhances DC-derived Th17 immune response against Candida albicans by activating IL-6/STAT3 in vitro

AimsEnhancing the potency of dendritic cells (DCs) by downregulating negative immunoregulatory pathways may provide immunotherapeutic possibilities against candidiasis. Main methodsIn this study, a si-RNA method is used to repress expression of the cytokine signaling-3 suppressor (SOCS3) in murine bone marrow-DCs, and then the maturation of DCs and the subsequent T-cell response after exposure to C. albicans are monitored in vitro. Key findingsAlong with a higher expression of the DC maturation markers CD40, CD86 and MHC-II, IL-6/STAT3 is markedly upregulated in the SOCS3 siRNA-treated DCs after exposure to C. albicans as compared with control DCs. In response to DCs maturation, CD4+ T cells have an increased expression of Th17 cell markers –– including the retinoic acid-related orphan nuclear hormone receptors γt (RORγt), IL-17A and IL-23R –– and increased release of IL-17. We note that this enhanced Th17 cell differentiation induced by siSOCS3-treated DCs in presence of C. albicans can be partly offset when anti-IL-6 antibody is added into the co-culture. SignificanceAs with SOCS1 in our previous report, suppression of SOCS3 alone also has the potential to fully activate DCs maturation. However, while SOCS1 knockdown in DCs during C. albicans infection specifically augments Th1 differentiation, SOCS3 silencing particularly increases Th17 differentiation.

Abstract 4001: Gremlin-1 augments the estrogen-related receptor α signaling: Implications for progression of breast cancer in synergistic manner

Abstract Gremlin-1 (GREM1), one of the bone morphogenic protein (BMP) antagonists, is known to be involved in organogenesis, tissue differentiation, and pathogenesis of several renal disorders including fibrosis, inflammation, and diabetes. Recently, it has also been reported that aberrant epithelial GREM1 expression initiates colonic tumorigenesis. However, the role of GREM1 in breast cancer remain largely elusive. We observed that GREM1 expression was highly increased in human breast cancer cells and tissues obtained from breast cancer patients. Furthermore, its overexpression is associated with poor prognosis of breast cancer patients, especially those with estrogen receptor (ER)-negative tumors. Suppression of GREM1 expression significantly inhibited the proliferation of SKBR3 human breast cancer cells in culture and xenograft mammary tumor growth while its overexpression enhanced their viability and invasiveness. Estrogen-related receptor α (ERRα) is an orphan nuclear hormone receptor and has recently attracted attention as a novel therapeutic target in the management of triple-negative breast cancers. We observed that ERRα binds directly to GREM1 promoter and modulates GREM1 expression. The mRNA level of GREM1 was reduced by an inverse agonist of ERRα, XCT790 and also by siRNA silencing of ERRα. Conversely, the overexpression of ERRα with its co-factor peroxisome proliferator-activated receptor gamma co-activator 1-α increased the mRNA level of GREM1. Surprisingly, the transcriptional activity of ERRα was found to be regulated by GREM1. The promoter activity of ERRα and the mRNA levels of ERRα target genes were highly increased in GREM1-overexpressing breast cancer cells. Treatment of MCF-7 cells with recombinant GREM1 protein also enhanced the ERRα promoter activity and transcription of its target genes. Taken together, our study identifies for the first time that the GREM1 can act as a downstream signaling molecule of the transcription factor ERRα and suggests a positive feedback loop between ERRα and GREM1, highlighting GREM1 as a potential diagnostic and therapeutic target for the treatment of ER-negative breast cancer. Citation Format: Sin-Aye Park, Bae-Jung Choi, Wonki Kim, Young-Joon Surh. Gremlin-1 augments the estrogen-related receptor α signaling: Implications for progression of breast cancer in synergistic manner [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4001.