Small molecule tertiary amines as agonists of the nuclear hormone receptor Rev-erbα

Structural basis of synthetic agonist activation of the nuclear receptor REV-ERB

The nuclear receptor REV-ERB plays an important role in a range of physiological processes. REV-ERB behaves as a ligand-dependent transcriptional repressor and heme has been identified as a physiological agonist. Our current understanding of how ligands bind to and regulate transcriptional repression by REV-ERB is based on the structure of heme bound to REV-ERB. However, porphyrin (heme) analogues have been avoided as a source of synthetic agonists due to the wide range of heme binding proteins and potential pleotropic effects. How non-porphyrin synthetic agonists bind to and regulate REV-ERB has not yet been defined. Here, we characterize a high affinity synthetic REV-ERB agonist, STL1267, and describe its mechanism of binding to REV-ERB as well as the method by which it recruits transcriptional corepressor both of which are unique and distinct from that of heme-bound REV-ERB.

Recent Progress in the Synthesis of Drugs and Bioactive Molecules Incorporating Nitro(het)arene Core

Aromatic nitro compounds play a unique role in the synthesis of drugs and pharmaceutically oriented molecules. This field of organic chemistry continues to be in demand and relevant. A significant number of papers are published annually on new general methods for the synthesis of nitrodrugs and related biomolecules. This review is an analysis of the literature on methods for the synthesis of both new and already-known aromatic and heteroaromatic nitrodrugs covering the period from 2010 to the present.

Recent advances in modulators of circadian rhythms: an update and perspective

Circadian rhythm is a universal life phenomenon that plays an important role in maintaining the multiple physiological functions and regulating the adaptability to internal and external environments of flora and fauna. Circadian alignment in humans has the greatest effect on human health, and circadian misalignment is closely associated with increased risk for metabolic syndrome, cardiovascular diseases, neurological diseases, immune diseases, cancer, sleep disorders, and ophthalmic diseases. The recent description of clock proteins and related post-modification targets was involved in several diseases, and numerous lines of evidence are emerging that small molecule modulators of circadian rhythms can be used to rectify circadian disorder. Herein, we attempt to update the disclosures about the modulators targeting core clock proteins and related post-modification targets, as well as the relationship between circadian rhythm disorders and human health as well as the therapeutic role and prospect of these small molecule modulators in circadian rhythm related disease.

The transcriptional repressor REV-ERB as a novel target for disease

REV-ERB is a member of the nuclear receptor superfamily of transcription factors involved in the regulation of many physiological processes, from circadian rhythm, to immune function and metabolism. Accordingly, REV-ERB has been considered as a promising, but difficult drug target for the treatment of numerous diseases. Here, we concisely review current understanding of the function of REV-ERB, modulation by endogenous factors and synthetic ligands, and the involvement of REV-ERB in select human diseases. Particular focus is placed on the medicinal chemistry of synthetic REV-ERB ligands, which demonstrates the need for higher quality ligands to aid in robust validation of this exciting target.

Targeting REV-ERBα for therapeutic purposes: promises and challenges

REV-ERBα (NR1D1) is a circadian clock component that functions as a transcriptional repressor. Due to its role in direct modulation of metabolic genes, REV-ERBα is regarded as an integrator of cell metabolism with circadian clock. Accordingly, REV-ERBα is first proposed as a drug target for treating sleep disorders and metabolic syndromes (e.g., dyslipidaemia, hyperglycaemia and obesity). Recent years of studies uncover a rather broad role of REV-ERBα in pathological conditions including local inflammatory diseases, heart failure and cancers. Moreover, REV-ERBα is involved in regulation of circadian drug metabolism that has implications in chronopharmacology. In the meantime, recent years have witnessed discovery of an array of new REV-ERBα ligands most of which have pharmacological activities in vivo. In this article, we review the regulatory role of REV-ERBα in various types of diseases and discuss the underlying mechanisms. We also describe the newly discovered ligands and the old ones together with their targeting potential. Despite well-established pharmacological effects of REV-ERBα ligands in animals (preclinical studies), no progress has been made regarding their translation to clinical trials. This implies certain challenges associated with drug development of REV-ERBα ligands. In particular, we discuss the potential challenges related to drug safety (or adverse effects) and bioavailability. For new drug development, it is advocated that REV-ERBα should be targeted to treat local diseases and a targeting drug should be locally distributed, avoiding the adverse effects on other tissues.

Development and implementation of a cell-based assay to discover agonists of the nuclear receptor REV-ERBα

The nuclear receptors are transcription factors involved in the regulation of a variety of physiological processes whose activity can be modulated by binding to relevant small molecule ligands. Their dysfunction has been shown to play a role in disease states such as diabetes, cancer, inflammatory diseases, and hormonal resistance ailments, which makes them interesting targets for drug discovery. The nuclear receptor REV-ERBα is involved in regulating the circadian rhythm and metabolism. Its natural ligand is heme and there is significant interest in identifying novel synthetic modulators to serve as tools to characterize its function and to serve as drugs in treating metabolic disorders. To do so, we established a mammalian cell-based two-hybrid assay system capable of measuring the interaction between REV-ERBα and its co-repressor, nuclear co-repressor 1. This assay was validated to industry standard criteria and was used to screen a subset of the LOPAC^®1280 library and 29568 compounds from a diverse compound library. Profiling of the primary hits in a panel of counter and selectivity assays confirmed that REV-ERBα activity can be modulated pharmacologically and chemical scaffolds have been identified for optimization.

In Vitro Metabolic Studies of REV-ERB Agonists SR9009 and SR9011

SR9009 and SR9011 are attractive as performance-enhancing substances due to their REV-ERB agonist effects and thus circadian rhythm modulation activity. Although no pharmaceutical preparations are available yet, illicit use of SR9009 and SR9011 for doping purposes can be anticipated, especially since SR9009 is marketed in illicit products. Therefore, the aim was to identify potential diagnostic metabolites via in vitro metabolic studies to ensure effective (doping) control. The presence of SR9009 could be demonstrated in a black market product purchased over the Internet. Via human liver microsomal metabolic assays, eight metabolites were detected for SR9009 and fourteen metabolites for SR9011 by liquid chromatography–high resolution mass spectrometry (LC–HRMS). Structure elucidation was performed for all metabolites by LC–HRMS product ion scans in both positive and negative ionization mode. Retrospective data analysis was applied to 1511 doping control samples previously analyzed by a full-scan LC–HRMS screening method to verify the presence of SR9009, SR9011 and their metabolites. So far, the presence of neither the parent compound nor the metabolites could be detected in routine urine samples. However, to further discourage use of these potentially harmful compounds, incorporation of SR9009 and SR9011 into screening methods is highly recommended.

Role of the clock gene Rev-erbα in metabolism and in the endocrine pancreas

Several hormones are regulated by circadian rhythms to adjust the metabolism to the light/dark cycles and feeding/activity patterns throughout the day. Circadian rhythms are mainly governed by the central clock located in the suprachiasmatic nucleus but also by clocks present in peripheral organs, like the endocrine pancreas. Plasma glucose levels and the main pancreatic hormones insulin and glucagon also exhibit daily variations. Alterations in circadian rhythms are associated with metabolic disturbances and pathologies such as obesity and diabetes. The molecular components of central and peripheral clocks and their regulatory mechanisms are well established. Among the different clock genes, Rev-erbα is considered one of the key links between circadian rhythms and metabolism. Rev-erbα is a critical part of a negative feedback loop in the core circadian clock and modulates the clock oscillatory properties. In addition, Rev-erbα plays an important role in the regulation of lipid and glucose metabolism, thermogenesis, adipocyte and muscle differentiation as well as mitochondrial function. In the endocrine pancreas, Rev-erbα regulates insulin and glucagon secretion and pancreatic β-cell proliferation. In the present review, we discuss all these subjects and, particularly, the role of the clock gene Rev-erbα in the endocrine pancreas.

Anti-proliferative actions of a synthetic REV-ERBα/β agonist in breast cancer cells

REV-ERBα and REV-ERBβ are nuclear receptors that are ligand-dependent transcriptional repressors. Heme is the natural ligand for these receptors, but several synthetic agonists and antagonists have been designed recently. The gene that encodes REV-ERBα, NR1D1, is closely associated with ERBB2, the gene that encodes the HER2 oncogene, which is amplified in HER2(+) breast cancers. We examined the effect of a synthetic REV-ERB agonist, SR9011, on a range of estrogen receptor positive (ER(+)), ER(-), HER2(+), HER2(-) and triple negative breast cancer cell lines. We found that SR9011 suppressed proliferation of the breast cancer cell lines regardless of their ER or HER2 status. SR9011 had no effect on MCF10A cell proliferation. SR9011 appears to pause the cell cycle of the breast cancer cells prior to M phase. Cyclin A (CCNA2) was identified as a direct target gene of REV-ERB suggesting that suppression of expression of this cyclin by SR9011 may mediate the cell cycle arrest. These data indicate that synthetic REV-ERB ligands may hold utility in treatment of diseases associated with uncontrolled cellular proliferation such as cancer.

Pharmacological targeting of the mammalian clock regulates sleep architecture and emotional behaviour

Synthetic drug-like molecules that directly modulate the activity of key clock proteins offer the potential to directly modulate the endogenous circadian rhythm and treat diseases associated with clock dysfunction. Here we demonstrate that synthetic ligands targeting a key component of the mammalian clock, the nuclear receptors REV-ERBα and β, regulate sleep architecture and emotional behaviour in mice. REV-ERB agonists induce wakefulness and reduce REM and slow-wave sleep. Interestingly, REV-ERB agonists also reduce anxiety-like behaviour. These data are consistent with increased anxiety-like behaviour of REV-ERBβ-null mice, in which REV-ERB agonists have no effect. These results indicate that pharmacological targeting of REV-ERB may lead to the development of novel therapeutics to treat sleep disorders and anxiety.

Nuclear receptor Rev-erbα: up, down, and all around

Rev-erbα is a nuclear receptor that links circadian rhythms to transcriptional control of metabolic pathways. Rev-erbα is a potent transcriptional repressor and plays an important role in the core mammalian molecular clock while also serving as a key regulator of clock output in metabolic tissues including liver and brown adipose tissue (BAT). Recent findings have shed new light on the role of Rev-erbα and its paralog Rev-erbβ in rhythm generation, as well as additional regulatory roles for Rev-erbα in other tissues that contribute to energy expenditure, inflammation, and behavior. This review highlights physiological functions of Rev-erbα and β in multiple tissues and discusses the therapeutic potential and challenges of targeting these pathways in human disease.

REV-ERB and ROR nuclear receptors as drug targets

The nuclear receptors REV-ERB (consisting of REV-ERBα and REV-ERBβ) and retinoic acid receptor-related orphan receptors (RORs; consisting of RORα, RORβ and RORγ) are involved in many physiological processes, including regulation of metabolism, development and immunity as well as the circadian rhythm. The recent characterization of endogenous ligands for these former orphan nuclear receptors has stimulated the development of synthetic ligands and opened up the possibility of targeting these receptors to treat several diseases, including diabetes, atherosclerosis, autoimmunity and cancer. This Review focuses on the latest developments in ROR and REV-ERB pharmacology indicating that these nuclear receptors are druggable targets and that ligands targeting these receptors may be useful in the treatment of several disorders.