Inactivation of the Nuclear Orphan Receptor COUP-TFII by Small Chemicals

Anti-angiogenesis and anti-immunosuppression gene therapy through targeting COUP-TFII in an in situ glioblastoma mouse model

Glioblastoma (GBM) is the most common and aggressive primary brain cancer; angiogenesis and immunosuppression exacerbate GBM progression. COUP-TFII demonstrates pro-angiogenesis activity; however, its role in glioma progression remains unclear. This study revealed that COUP-TFII promotes angiogenesis in gliomas by inducing transdifferentiation of glioma cells into endothelial-like cells. Mechanistic investigation suggested that COUP-TFII as a transcription factor exerts its function via binding to the promoter of TXNIP. Interestingly, COUP-TFII knockdown attenuated tumorigenesis and tumor progression in an immunocompetent mouse model but promoted tumor progression in an immuno-deficient mouse model. As an explanation, repression of COUP-TFII induces cellular senescence and activates immune surveillance in glioma cells in vitro and in vivo. In addition, we used heparin-polyethyleneimine (HPEI) nanoparticles to deliver COUP-TFII shRNA, which regulated tumor angiogenesis and immunosuppression in an in situ GBM mouse model. This study provides a novel strategy and potential therapeutic targets to treat GBM.

Astragaloside IV attenuates sunitinib-associated cardiotoxicity by inhibiting COUP-TFII

Sunitinib (SU) is widely used to treat solid tumors but it can be cardiotoxic and often leads to drug withdrawn or discontinuation. Astragaloside IV (ASIV) is the essential active component of the Chinese herb Astragalus membranaceus which shows potential cardioprotective effects. Herein, we investigated the effect of ASIV on SU-associated cardiotoxicity and its mechanisms. We showed that ASIV significantly ameliorated SU-induced myocardial injury in mice, as evidenced by an improvement in left ventricular ejection fraction (EF) and a decrease in blood pressure and serum concentration of myocardial injury markers. ASIV attenuated SU-induced myocardial inflammatory infiltration and fibrotic lesions. In addition, ASIV suppressed SU-induced myocardial oxidative stress and apoptosis both in vitro and in vivo. Furthermore, SU increased COUP-TFII expression both in mRNA and protein levels in mice myocardial tissue, primary neonatal rat cardiomyocytes (NRCMs) and H9c2 cell lines, and this effect was rescued by ASIV. Knockdown of COUP-TFII reduced the oxidative stress and apoptosis induced by SU in NRCMs and H9c2 cell lines. However, the overexpression of COUP-TFII blocked the protective effects of ASIV on SU-treated cardiomyocytes. Thus, our results demonstrated that ASIV ameliorated SU-indued cardiotoxicity by inhibiting COUP-TFII, suggesting that ASIV might be a potential therapeutic strategy for the prevention of SU-associated cardiotoxicity.

Neonatal intake of Omega-3 fatty acids enhances lipid oxidation in adipocyte precursors

Establishing metabolic programming begins during fetal and postnatal development, and early-life lipid exposures play a critical role during neonatal adipogenesis. We define how neonatal consumption of a low omega-6 to -3 fatty acid ratio (n6/n3 FA ratio) establishes FA oxidation in adipocyte precursor cells (APCs) before they become adipocytes. In vivo, APCs isolated from mouse pups exposed to the low n6/n3 FA ratio had superior FA oxidation capacity, elevated beige adipocyte mRNAs Ppargc1α, Ucp2, and Runx1, and increased nuclear receptor NR2F2 protein. In vitro, APC treatment with NR2F2 ligand-induced beige adipocyte mRNAs and increased mitochondrial potential but not mass. Single-cell RNA-sequencing analysis revealed low n6/n3 FA ratio yielded more mitochondrial-high APCs and linked APC NR2F2 levels with beige adipocyte signatures and FA oxidation. Establishing beige adipogenesis is of clinical relevance, because fat depots with energetically active, smaller, and more numerous adipocytes improve metabolism and delay metabolic dysfunction.

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.

Role of Nuclear Receptors in Controlling Erythropoiesis

Nuclear receptors (NRs), are a wide family of ligand-regulated transcription factors sharing a common modular structure composed by an N-terminal domain and a ligand-binding domain connected by a short hinge linker to a DNA-binding domain. NRs are involved in many physiological processes, including metabolism, reproduction and development. Most of them respond to small lipophilic ligands, such as steroids, retinoids, and phospholipids, which act as conformational switches. Some NRs are still "orphan" and the search for their ligands is still ongoing. Upon DNA binding, NRs can act both as transcriptional activators or repressors of their target genes. Theoretically, the possibility to modulate NRs activity with small molecules makes them ideal therapeutic targets, although the complexity of their signaling makes drug design challenging. In this review, we discuss the role of NRs in erythropoiesis, in both homeostatic and stress conditions. This knowledge is important in view of modulating red blood cells production in disease conditions, such as anemias, and for the expansion of erythroid cells in culture for research purposes and for reaching the long-term goal of cultured blood for transfusion.

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.

NR2F2 plays a major role in insulin-induced epithelial-mesenchymal transition in breast cancer cells

Background

The failure of treatment for breast cancer usually results from distant metastasis in which the epithelial-mesenchymal transition (EMT) plays a critical role. Hyperinsulinemia, the hallmark of Type 2 diabetes mellitus (T2DM), has been regarded as a key risk factor for the progression of breast cancer. Nuclear receptor subfamily 2, group F, member 2 (NR2F2) has been implicated in the development of breast cancer, however its contribution to insulin-induced EMT in breast cancer remains unclear.

Methods

Overexpression and knockdown of NR2F2 were used in two breast cancer cell lines, MCF-7 and MDA-MB-231 to investigate potential mechanisms by which NR2F2 leads to insulin-mediated EMT. To elucidate the effects of insulin and signaling events following NR2F2 overexpression and knockdown, Cells’ invasion and migration capacity and changes of NR2F2, E-cadherin, N-cadherin and vimentin were investigated by real-time RT-PCR and western blot.

Results

Insulin stimulation of these cells increased NR2F2 expression levels and promoted cell invasion and migration accompanied by alterations in EMT-related molecular markers. Overexpression of NR2F2 and NR2F2 knockdown demonstrated that NR2F2 expression was positively correlated with cell invasion, migration and the expression of N-cadherin and vimentin. In contrast, NR2F2 had an inverse correlation with E-cadherin expression. In MDA-MB-231, both insulin-induced cell invasion and migration and EMT-related marker alteration were abolished by NR2F2 knockdown.

Conclusions

These results suggest that NR2F2 plays a critical role in insulin-mediated breast cancer cell invasion, migration through its effect on EMT.

Patent highlights October-November 2019

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

Small-molecule inhibitor targeting orphan nuclear receptor COUP-TFII for prostate cancer treatment

The orphan nuclear receptor COUP-TFII is expressed at a low level in adult tissues, but its expression is increased and shown to promote progression of multiple diseases, including prostate cancer, heart failure, and muscular dystrophy. Suppression of COUP-TFII slows disease progression, making it an intriguing therapeutic target. Here, we identified a potent and specific COUP-TFII inhibitor through high-throughput screening. The inhibitor specifically suppressed COUP-TFII activity to regulate its target genes. Mechanistically, the inhibitor directly bound to the COUP-TFII ligand-binding domain and disrupted COUP-TFII interaction with transcription regulators, including FOXA1, thus repressing COUP-TFII activity on target gene regulation. Through blocking COUP-TFII's oncogenic activity in prostate cancer, the inhibitor efficiently exerted a potent antitumor effect in xenograft mouse models and patient-derived xenograft models. Our study identified a potent and specific COUP-TFII inhibitor that may be useful for the treatment of prostate cancer and possibly other diseases.

COUP-TFII in Health and Disease

The nuclear receptors (NRs) belong to a vast family of evolutionary conserved proteins acting as ligand-activated transcription factors. Functionally, NRs are essential in embryogenesis and organogenesis and in adulthood they are involved in almost every physiological and pathological process. Our knowledge of NRs action has greatly improved in recent years, demonstrating that both their expression and activity are tightly regulated by a network of signaling pathways, miRNA and reciprocal interactions. The Chicken Ovalbumin Upstream Promoter Transcription Factor II (COUP-TFII, NR2F2) is a NR classified as an orphan due to the lack of a known natural ligand. Although its expression peaks during development, and then decreases considerably, in adult tissues, COUP-TFII is an important regulator of differentiation and it is variably implicated in tissues homeostasis. As such, alterations of its expression or its transcriptional activity have been studied and linked to a spectrum of diseases in organs and tissues of different origins. Indeed, an altered COUP-TFII expression and activity may cause infertility, abnormality in the vascular system and metabolic diseases like diabetes. Moreover, COUP-TFII is actively investigated in cancer research but its role in tumor progression is yet to be fully understood. In this review, we summarize the current understanding of COUP-TFII in healthy and pathological conditions, proposing an updated and critical view of the many functions of this NR.

Development of novel silanol-based human pregnane X receptor (PXR) agonists with improved receptor selectivity

Pregnane X receptor (PXR) is a ligand-dependent transcription factor that is considered to be a potential therapeutic target for multiple diseases. Herein, we report the development and structure-activity relationship studies of a new series of hPXR agonists. Focusing on our recently developed silanol-sulfonamide scaffold, we developed the potent hPXR agonist 28, which shows good selectivity over hLXRα and β, hFXR, and hRORα and γ. Examination of the structure-activity relationship suggested a possible strategy to manipulate the selectivity. Docking simulation indicated the presence of an additional binding cavity and polar contacts in the ligand-binding pocket of hPXR. This information should be helpful for the future development of more potent and selective hPXR ligands.

The RBM14/CoAA-interacting, long intergenic non-coding RNA Paral1 regulates adipogenesis and coactivates the nuclear receptor PPARγ

Adipocyte differentiation and function relies on a network of transcription factors, which is disrupted in obesity-associated low grade, chronic inflammation leading to adipose tissue dysfunction. In this context, there is a need for a thorough understanding of the transcriptional regulatory network involved in adipose tissue pathophysiology. Recent advances in the functional annotation of the genome has highlighted the role of non-coding RNAs in cellular differentiation processes in coordination with transcription factors. Using an unbiased genome-wide approach, we identified and characterized a novel long intergenic non-coding RNA (lincRNA) strongly induced during adipocyte differentiation. This lincRNA favors adipocyte differentiation and coactivates the master adipogenic regulator peroxisome proliferator-activated receptor gamma (PPARγ) through interaction with the paraspeckle component and hnRNP-like RNA binding protein 14 (RBM14/NCoAA), and was therefore called PPARγ-activator RBM14-associated lncRNA (Paral1). Paral1 expression is restricted to adipocytes and decreased in humans with increasing body mass index. A decreased expression was also observed in diet-induced or genetic mouse models of obesity and this down-regulation was mimicked in vitro by TNF treatment. In conclusion, we have identified a novel component of the adipogenic transcriptional regulatory network defining the lincRNA Paral1 as an obesity-sensitive regulator of adipocyte differentiation and function.

Trichoplax adhaerens reveals a network of nuclear receptors sensitive to 9-cis-retinoic acid at the base of metazoan evolution

Trichoplax adhaerens, the only known species of Placozoa is likely to be closely related to an early metazoan that preceded branching of Cnidaria and Bilateria. This animal species is surprisingly well adapted to free life in the World Ocean inhabiting tidal costal zones of oceans and seas with warm to moderate temperatures and shallow waters. The genome of T. adhaerens (sp. Grell) includes four nuclear receptors, namely orthologue of RXR (NR2B), HNF4 (NR2A), COUP-TF (NR2F) and ERR (NR3B) that show a high degree of similarity with human orthologues. In the case of RXR, the sequence identity to human RXR alpha reaches 81% in the DNA binding domain and 70% in the ligand binding domain. We show that T. adhaerens RXR (TaRXR) binds 9-cis retinoic acid (9-cis-RA) with high affinity, as well as high specificity and that exposure of T. adhaerens to 9-cis-RA regulates the expression of the putative T. adhaerens orthologue of vertebrate L-malate-NADP⁺ oxidoreductase (EC 1.1.1.40) which in vertebrates is regulated by a heterodimer of RXR and thyroid hormone receptor. Treatment by 9-cis-RA alters the relative expression profile of T. adhaerens nuclear receptors, suggesting the existence of natural ligands. Keeping with this, algal food composition has a profound effect on T. adhaerens growth and appearance. We show that nanomolar concentrations of 9-cis-RA interfere with T. adhaerens growth response to specific algal food and causes growth arrest. Our results uncover an endocrine-like network of nuclear receptors sensitive to 9-cis-RA in T. adhaerens and support the existence of a ligand-sensitive network of nuclear receptors at the base of metazoan evolution.

Identification and characterization of long non-coding RNAs in subcutaneous adipose tissue from castrated and intact full-sib pair Huainan male pigs

Background

Long non-coding RNAs (lncRNAs) regulate adipose tissue metabolism, however, their function on testosterone deficiency related obesity in humans is less understood. For this research, intact and castrated male pigs are the best model animal because of their similar proportional organ sizes, cardiovascular systems and metabolic features.

Results

We identified lncRNAs in subcutaneous adipose tissue by deep RNA-sequencing using the intact and castrated Huainan male pigs. The results showed that castration reduced serum testosterone but increased body fatness-related traits (serum triglyceride levels, backfat thickness, intramuscular fat content, and adipocyte size). Meanwhile, 343 lncRNAs from subcutaneous adipose tissue were identified, including 223 intergenic lncRNAs (lincRNAs), 68 anti-sense lncRNAs, and 52 intronic lncRNAs. It was predicted that there were 416 recognition sites for C/EBPα in the 303 lncRNA promoter region, and 13 adipogenesis-promoting miRNAs and five adipogenesis-depressing miRNAs target these lncRNAs. Eighteen lncRNAs, including nine up- and nine down-regulated had more than 2-fold differential expression between the castrated and intact male pigs (q-value < 0.05). Functional analysis indicated that these 18 lncRNAs and their target genes were involved in fatty acid, insulin, and the adipocytokine signaling pathway. We further analyzed the features of a conserved mouse lncRNA gene ENSMUST00000189966 and found it mainly expressed in the cell nucleus and target the Nuclear Receptor Subfamily 2 Group F Member 2 (NR2F2) gene. In 3 T3-L1 cells, differentiation down-regulated their expression, but dihydrotestosterone (DHT) significantly up-regulated their expression in a concentration-dependent manner (P < 0.05).

Conclusions

These results suggested that lncRNAs and their target genes might participated in the castration-induced fat deposition and provide a new therapeutic target for combatting testosterone deficiency-related obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3907-z) contains supplementary material, which is available to authorized users.