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Cooling patients to sub‐physiological temperatures is an integral part of modern medicine. We show that cold exposure induces temperature‐specific changes to the higher‐order chromatin and gene expression profiles of human cells. These changes are particularly dramatic at 18°C, a temperature synonymous with that experienced by patients undergoing controlled deep hypothermia during surgery. Cells exposed to 18°C exhibit largely nuclear‐restricted transcriptome changes. These include the nuclear accumulation of mRNAs encoding components of the negative limbs of the core circadian clock, most notably REV‐ERBα. This response is accompanied by compaction of higher‐order chromatin and hindrance of mRNPs from engaging nuclear pores. Rewarming reverses chromatin compaction and releases the transcripts into the cytoplasm, triggering a pulse of negative limb gene proteins that reset the circadian clock. We show that cold‐induced upregulation of REV‐ERBα is sufficient to trigger this reset. Our findings uncover principles of the cellular cold response that must be considered for current and future applications involving therapeutic deep hypothermia. Synopsis: How human cells respond to cold temperatures such as surgery‐associated deep hypothermia is largely elusive. Here, low temperatures are found to affect chromatin architecture, shape temperature‐specific nuclear and cytoplasmic transcriptomes, and subsequently reset the circadian rhythm in human cells. Exposure of human cells to varying sub‐physiological temperatures induces chromatin compaction in a non‐linear fashion.Chromatin compaction at 18°C correlates with nuclear retention of mRNAs.Incubation at 18°C forces the nuclear‐restricted upregulation of mRNAs encoding circadian clock repressor/co-repressor genes, most notably REV‐ERBα.Rewarming cells to 37°C causes release of nuclear‐accumulated mRNAs into the cytoplasm, resetting the cellular circadian rhythm. [ABSTRACT FROM AUTHOR]

BACKGROUND: The orphan nuclear receptor Rev-erbα has been demonstrated to play important roles during bone metabolism. However, the specific mechanism underlying osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is still unclear. OBJECTIVE: To explore whether the orphan nuclear receptor Rev-erbα participates in the osteogenesis process of BMSCs in mice. METHODS: Mouse BMSCs were isolated and cultured by the whole bone marrow adherence method. And the lentivirus vector carrying the Rev-erbα gene was constructed and then transfected into the BMSCs. Real-time PCR was conducted to detect the mRNA level of Rev-erbα at 48 hours after transfection. There were three groups in the experiment: an experimental group with BMSCs transfected with lentiviral vectors containing overexpressed Rev-erbα gene and EGFP gene, a positive control group with BMSCs transfected with empty lentiviral vectors containing only EGFP gene, and a negative control group. Then the BMSCs were induced to differentiate into osteoblasts after the transfection and we detected the mRNA level of alkaline phosphatase, osteopontin, and osteocalcin using real-time PCR at 0, 7, and 14 days after induction. RESULTS AND CONCLUSION: The lentivirus vector carrying Rev-erbα gene was successfully transfected into BMSCs, and expressed stably. An increase in the mRNA levels of alkaline phosphatase and osteopontin was detected in each group when cultured in osteogenic medium; however, there was no significant difference between groups. The mRNA level of osteocalcin was also increased in each group, and moreover, the mRNA level in the experimental group was significantly lower than that in the two control groups (P < 0.05). These results indicate that Rev-erbα transfection reduces the osteogenic ability of BMSCs, and the expression of osteocalcin, a late-stage osteogenic marker, is inhibited, indicating that the late-stage osteogenesis of BMSCs may be influenced by Rev-erbα. [ABSTRACT FROM AUTHOR]

Hyperhomocysteinemia is associated with poor health, including cardiovascular and brain diseases. Puerarin, initially isolated from Puerariae radix, has been shown to possess anti-hyperhomocysteinemia effect. However, the mechanism of puerarin action remains unknown. Here, we uncovered that puerarin targeted the circadian clock protein Rev-erbα to alleviate hyperhomocysteinemia in mice in a circadian time-dependent manner. We first identified puerarin as an antagonist of Rev-erbα based on luciferase reporter, Gal4 co-transfection and target gene expression assays. Consistent with an antagonistic effect, puerarin induced mRNA and protein expressions of Bhmt, Cbs and Cth (three enzymes involved in homocysteine catabolism and known targets of Rev-erbα) in Hepa-1c1c7 cells. These induction effects of puerarin were lost in Rev-erbα-deficient cells. Furthermore, puerarin dose-dependently alleviated methionine-induced hyperhomocysteinemia in mice as evidenced by decreased levels of total homocysteine and triglyceride. This was accompanied by increased expressions of Bhmt, Cbs and Cth in the liver. Moreover, puerarin dosed at ZT10 generated stronger pharmacological effects than drug dosed at ZT22 consistent with diurnally rhythmic expression of Rev-erbα (a high expression at ZT10 and a low expression at ZT22). In conclusion, puerarin targets Rev-erbα to alleviate hyperhomocysteinemia in mice in a circadian time-dependent manner. The finding of a circadian gene as drug target encourages chronotherapeutic practices on puerarin and related medications for optimized efficacy.

Background/Aims: Angiotensin II (Ang II) regulates the expression of some core clock genes; excess Ang II leads to atherosclerosis advancement. Macrophage Rev-erbα mediates clockwork and inflammation, and plays a role in atherosclerotic lesion progression. However, the role of Ang II in regulating Rev-erbα expression in macrophages remains unclarified. Methods: We induced THP-1 macrophages by phorbol 12-myristate 13-acetate and investigated the effect of Ang II on Rev-erbα expression via real-time polymerase chain reaction, western blotting and small interfering RNA (siRNA) techniques. The cytotoxicity of the Rev-erbα agonist SR9009 was analyzed using a (3-[4,5-dimethylthiazol-2-yl])-2,5- diphenyltetrazolium bromide assay. Results: Ang II suppressed Rev-erbα mRNA and protein expression in THP-1 macrophages in a dose and time dependent manner. This effect was mediated via Ang II type 1 receptor (AT1R), and not Ang II type 2 receptor or peroxisome proliferator-activated receptor γ (PPARγ). Consistent with Rev-erbα expression regulated by Ang II, the liver X receptor α (LXRα) protein expression was downregulated in a time-dependent manner after Ang II treatment. The activation or silence of LXRα significantly increased or decreased Rev-erbα expression regulated by Ang II, respectively. This suggests that LXRα is involved in the effect of Ang II on Rev-erbα expression. MMP-9 mRNA expressions were significantly suppressed by SR9009 in THP-1 and RAW264.7 macrophages; moreover, SR9009-treatment significantly reduced Ang II–induced MMP-9 protein expressions in two types of macrophages. Conclusion: Ang II downregulates Rev-erbα expression in THP-1 macrophages via the AT1R/LXRα pathway.

Hepatic ischemia-reperfusion (I/R) injury is a complex pathophysiological process that often times occurs in liver transplantation, hepatectomy, and ischemic shock. Aberrant activation of inflammatory responses has been implicated in hepatic I/R injury. In this study, we aimed to investigate the role of circadian clock gene Rev-erbα (a well-known regulator of inflammation) in hepatic I/R injury. We first showed that Rev-erbα ablation sensitized mice to hepatic I/R injury as evidenced by higher levels of plasma alanine aminotransferase and aspartate aminotransferase, an increased histological score, as well as enhanced hepatic myeloperoxidase activity in Rev-erbα −/− mice. More severe hepatic I/R injury in Rev-erbα −/− mice was accompanied by higher expression of pro-inflammatory cytokines, exacerbated activation of Nlrp3 inflammasome, and more extensive infiltration of inflammatory cells. Moreover, pharmacological activation of Rev-erbα by SR9009 significantly alleviated the hepatic damage and inflammatory responses. In addition, I/R operation started at ZT18 (corresponding to low Rev-erbα expression) caused more severe liver damage and inflammatory responses in wild-type mice as compared to operation started at ZT6 (corresponding to high Rev-erbα expression), supporting a protective effect of Rev-erbα on hepatic I/R injury. Collectively, Rev-erbα protects hepatic I/R injury probably via repression of inflammatory responses, and targeting Rev-erbα may be a promising approach for management of hepatic I/R injury. • Rev-erbα ablation sensitizes mice to hepatic I/R injury possibly via repressing the inflammatory responses. • Rev-erbα agonist SR9009 alleviates hepatic I/R injury in mice. • Hepatic I/R injury and inflammatory responses depend on the time of I/R operation. [ABSTRACT FROM AUTHOR]

The REV‐ERBα receptor has a recognised role in the regulation of the circadian rhythm system. However, recent evidence suggests that it also contributes to energy balance regulation. Both expression and function of REV‐ERBα can be influenced by the energy status of the body. Considering the possibility of the involvement of REV‐ERBα in the regulation of energy balance, which is critically regulated by the hypothalamus, and based on the impact of intermittent fasting, the present study evaluated the effects of central administration of REV‐ERBα agonist on energy balance in rats exposed to 24 hours of fasting or ad lib. feeding conditions. Initially, 24‐hour fasted rats received an acute i.c.v. administration of agonist at doses of 1, 5, 10 or 15 μg per rat and feed efficiency was evaluated. Because 10 μg was a sufficient dose to affect feed efficiency, subsequent experiments used this dose to assess effects of agonist on the following parameters: energy expenditure induced by physical activity and locomotor activity, time spent in physical activity over 24 hours, and glucose and insulin tolerance. In fasted rats, the agonist promoted increased food intake and feed efficiency, with a greater body weight gain associated with less time spent in locomotor activity, suggesting a reduction in energy expenditure induced by physical activity. Furthermore, a reduction in glucose tolerance was noted. By contrast, free‐fed rats exhibited reduced food intake and feed efficiency with decreased body weight gain along with an increase in locomotor activity and physical activity‐dependent energy expenditure. Thus, i.c.v. administration of REV‐ERBα agonist regulates energy balance depending on the energy status of the organism; that is, it promotes a positive energy balance in the fasted state and a negative energy balance in the fed state. These results may be useful in understanding the underlying mechanisms of energy balance disorders and intermittent fasting for body weight control. [ABSTRACT FROM AUTHOR]

Background: A hallmark of temporal lobe epilepsy (TLE) is brain inflammation accompanied by neuronal demise. Accumulating evidence demonstrates that Rev-Erbα is involved in regulating neuroinflammation and determining the fate of neurons. Therefore, we studied the expression and cellular distribution of Rev-Erbα in the epileptogenic zone of TLE and the effect of treatment with the Rev-Erbα specific agonist SR9009 in the pilocarpine model.Methods: The expression pattern of Rev-Erbα was investigated by western blotting, immunohistochemistry, and immunofluorescence labeling in patients with TLE. Next, the effects of SR9009 on neuroinflammation, neuronal apoptosis, and neuronal loss in the mouse hippocampus 7 days after status epilepticus (SE) were assessed by western blotting, immunofluorescence labeling staining, and TUNEL staining.Results: The western blotting, immunohistochemistry, and immunofluorescence labeling results revealed that Rev-Erbα was downregulated in the epileptogenic zone of TLE patients and mainly localized in neurons, astrocytes, and presumably microglia. Meanwhile, the expression of Rev-Erbα was decreased in the hippocampus and temporal neocortex of mice treated with pilocarpine in the early post-SE and chronic phases. Interestingly, the expression of Rev-Erbα in the normal hippocampus showed a 24-h rhythm; however, the rhythmicity was disturbed in the early phase after SE, and this disturbance was still present in epileptic animals. Our further findings revealed that treatment with SR9009 inhibited NLRP3 inflammasome activation, inflammatory cytokine (IL-1β, IL-18, IL-6, and TNF-α) production, astrocytosis, microgliosis, and neuronal damage in the hippocampus after SE.Conclusions: Taken together, these results suggested that a decrease in Rev-Erbα in the epileptogenic zone may contribute to the process of TLE and that the activation of Rev-Erbα may have anti-inflammatory and neuroprotective effects. [ABSTRACT FROM AUTHOR]

Circadian dysregulation involved in the pathophysiology of spinal cord injury (SCI). Modulation of circadian rhythms hold promise for the SCI treatment. Here, we aim to investigated the mechanism of olfactory ensheathing cells (OEC) in alleviating neuroinflammation via modulating clock gene expression in microglia. In this study, SCI rats were randomly divided into OEC group and vehicle group. At 1 day after the surgery, OECs were intravenously transplanted into OEC group SCI rat, while the rats in vehicle group received culture medium. After 7 days post of OEC transplantation, tissues were collected from the brain (prefrontal cortex, hypothalamus, spinal cord) for PCR, western blotting and immunohistochemistry (IHC) assay at zeitgeber time (ZT) 6, ZT 12, ZT 18, and ZT 24. The roles of OEC in modulating REV-ERBα in microglia were studied by experimental inhibition of gene expression and the co-culture experiment. In the vehicle group, IHC showed a significant increase of Iba-1 expression in the cerebral white matter and spinal cord compared with control group ( P < 0.0001 for all comparisons). The expression of Iba-1 was significantly decreased ( P < 0.0001 for all comparisons). In the OEC group, the expression of PER 1, PER 2, CLOCK, and REV-ERBα was in a rhythmical manner in both spinal cord and brain regions. SCI disrupted their typical rhythms. And OECs transplantation could modulate those dysregulations by upregulating REV-ERBα. In vitro study showed that OECs couldn't reduce the activation of REV-ERBα inhibited microglia. The intravenous transplantation of OECs can mediate cerebral and spinal microglia activation through upregulation REV-ERBα after SCI., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Progressive lung injury and pulmonary inflammation can be induced by an intraperitoneal injection of lipopolysaccharide (LPS). Interleukin-1β (IL-1β) is a key pro-inflammatory cytokine that can further exaggerate inflammation, which is cleaved and activated by the NALP3 inflammasome. Although the nuclear receptor Rev-erbα attenuates the level of LPS-induced pulmonary inflammation, the mechanism remains unclear. In this study, we investigated the influence of LPS-induced production of IL-1β and Rev-erbα on the development of lung inflammation. Herein, we demonstrate that Rev-erbα reduces IL-1β production and lung injury following an intraperitoneal injection of LPS, which is dependent on the NF-κB/NALP3 pathway. Thus, Rev-erbα is able to decrease the extent of acute lung injury by regulating IL-1β production. This mechanism may represent a potential novel therapeutic approach for lung injury. • We firstly demonstrate that Rev-erbα inhibit IL-1β production to reduce lung injury through NF-κB/NALP3 pathway in mice model. Thus, Rev-erbα might be a good target to decrease the extent of acute lung injury. This mechanism may represent a potential novel therapeutic approach for lung injury. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract REV-ERBα (NR1D1) is a nuclear heme receptor that controls many cellular processes including cell differentiation, lipid metabolism, and inflammatory responses. Although REV-ERBα has been also implicated in regulation of glucose homeostasis, the mechanism for this regulation remains unclear. Here we investigate a potential role of REV-ERBα in regulation of PCK1 (phosphoenolpyruvate carboxykinase 1), a rate-limiting enzyme in gluconeogenesis. Hepatoma cells (Hepa-1c1c7 and HepG2 cells), wild-type mice and streptozotocin-induced diabetic mice were treated with SR9009, a specific REV-ERBα agonist. The relative mRNA and protein levels of enzymes in the cells or mouse livers were determined by qPCR and Western blotting, respectively. The fasting plasma glucose test was performed to determine the effects of Rev-erbα on glucose homeostasis. Transcriptional regulation of Pck1 by Rev-erbα was investigated using a combination of luciferase reporter, mobility shift, and chromatin immunoprecipitation (ChIP) assays. SR9009 treatment significantly decreased the mRNA level of Pck1 in mouse hepatoma Hepa-1c1c7 cells, whereas other major enzymes involved in gluconeogenesis (pyruvate carboxylase, glucose-6-phosphatase, fructose bisphosphatase and Pck2) and in glycolysis (phosphofructokinase and hexokinase-1) were unaffected. Consistent with the mRNA change, the protein level of Pck1 was down-regulated. Similarly, a repressive action of REV-ERBα on PCK1 expression was observed in human HepG2 hepatoma cells. SR9009 administration to wild-type or diabetic mice significantly reduced the level of fasting plasma glucose. This coincided with decreased mRNA and protein levels of Pck1 in the liver. In addition, the diabetic mice showed an improvement in glucose tolerability after SR9009 treatment. Promoter analysis, mobility shift, and ChIP assays revealed that Rev-erbα trans-repressed Pck1 through direct binding to -325 to -320 bp region (a RevRE site) in the gene promoter. In conclusion, Rev-erbα activation down-regulates hepatic Pck1 to lower plasma glucose. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Circadian clock is known to modulate phase I metabolism, however whether and how the phase II enzymes UDP-glucuronosyltransferases (UGTs) are regulated by circadian clock are largely unknown. In this study, we aimed to investigate a potential role of the clock gene Rev-erbα in regulation of Ugt2b enzymes. Ugt2b mRNA and protein expression in mouse livers were determined at a 4-h interval around the clock. Ugt2b activity was probed using morphine as a specific substrate. Regulation of Ugt2b by Rev-erbα was investigated using mouse hepatoma Hepa-1c1c7 cells and Rev-erbα knock-out (Rev-erbα−/−) mice. Luciferase reporter, mobility shift and chromatin immunoprecipitation (ChIP) assays were performed to identify the Rev-erbα binding site in Ugt2b36 promoter. Circadian variations in hepatic mRNA expression were observed for six Ugt2b genes (Ugt2b1 , Ugt2b5 , Ugt2b35 , Ugt2b36 , Ugt2b37 , and Ugt2b38) in mice. Likewise, the total Ugt2b protein showed a circadian fluctuation. Glucuronidation of morphine (an Ugt2b substrate) both in vitro and in vivo was dosing-time dependent. Morphine glucuronidation was more extensive at the dosing time of ZT2 than at ZT14 consistent with the Ugt2b protein levels. Furthermore, Rev-erbα knockdown significantly increased Ugt2b mRNA and protein in Hepa-1c1c7 cells, whereas Rev-erbα overexpression or activation down-regulated Ugt2b expression. Moreover, Rev-erbα ablation in mice up-regulated the mRNA and protein expression of Ugt2b and blunted Ugt2b rhythmicity in the liver. In addition, Rev-erbα repressed the transcription of Ugt2b36 through specific binding to the −30 to −18 bp of promoter region based on a combination of luciferase reporter, mobility shift and ChIP assays. In summary, the clock gene Rev-erbα negatively regulates the expressions of Ugt2b genes, contributing to their circadian variations. [ABSTRACT FROM AUTHOR]

Most living organisms show circadian rhythms in physiology and behavior. These oscillations are generated by endogenous circadian clocks, present in virtually all cells where they control key biological processes. To study peripheral clocks in vivo, we developed an original model, the Rev-Luc mouse to follow noninvasively and longitudinally Rev-Luc oscillations in peripheral clocks using in vivo bioluminescence imaging. We found in vitro and in vivo a robust diurnal rhythm of Rev-Luc, mainly in liver, intestine, kidney and adipose tissues. We further confirmed in vivo that Rev-Luc peripheral tissues are food-entrainable oscillators, not affected by age or sex. These data strongly support the relevance of the Rev-Luc model for circadian studies, especially to investigate in vivo the establishment and the entrainment of the rhythm throughout ontogenesis. We then showed that Rev-Luc expression develops dynamically and gradually, both in amplitude and in phase, during fetal and postnatal development. We also demonstrate for the first time that the immature peripheral circadian system of offspring in utero is mainly entrained by maternal cues from feeding regimen. The prenatal entrainment will also differentially determine the Rev-Luc expression in pups before weaning underlining the importance of the maternal chrononutrition on the circadian system entrainment of the offspring. [ABSTRACT FROM AUTHOR]

Polyamines stimulate the synthesis of specific proteins at the level of translation, and the genes encoding these proteins are termed as the “polyamine modulon”. The circadian clock generates daily rhythms in mammalian physiology and behavior. We investigated the role of polyamines in the circadian rhythm using control and polyamine-reduced NIH3T3 cells. The intracellular polyamines exhibited a rhythm with a period of about 24 h. In the polyamine-reduced NIH3T3 cells, the circadian period of circadian clock genes was lengthened and the synthesis of BMAL1 and REV-ERBα was significantly reduced at the translation level. Thus, the mechanism of polyamine stimulation of these protein syntheses was analyzed using NIH3T3 cells transiently transfected with genes encoding enhanced green fluorescent protein (EGFP) fusion mRNA with normal or mutated 5′-untranslated region (5′-UTR) of Bmal1 or Rev-erbα mRNA. It was found that polyamines stimulated BMAL1 and REV-ERBα synthesis through the enhancement of ribosomal shunting during the ribosome shunting within the 5′-UTR of mRNAs. Accordingly, the genes encoding Bmal1 and Rev-erbα were identified as the members of “polyamine modulon”, and these two proteins are significantly involved in the circadian rhythm control.

Circadian clocks are endogenous and biological oscillations that occur with a period of

Microgravity and sudden changes of gravitational forces exert numerous effects on tissues, organs and apparatus. Responses to these forces variably applied to cells indicate the existence of mechanotransduction pathways able to modulate transcription. Oscillation of circadian clocks similarly influences many cellular and metabolic processes. Here we hypothesized that signals derived from changes of gravitational forces applied to epidermal cells might influence their physiology in harmony with the oscillation of the molecular clock. In this study, we describe amplified oscillations ofBmal1 circadian clock gene in human keratinocytes exposed to short simulated microgravity and to rapid variation of gravitational forces. We found that exposure to microgravity enhances the amplitude of the Bmal1 feedback loop sustained by an apparently lower variability ofRev‐erbα transcription, while recovery from microgravity is characterized by increased amplitude of Bmal1 expression and elongation of the oscillatory periods of Bmal1 and Rev‐erbα. These data highlight the existence of integrated signaling network connecting mechanosensitive pathways to circadian gene regulation.

Age-related macular degeneration is a primary cause of blindness in the older adult population. Past decades of research in the pathophysiology of the disease have resulted in breakthroughs in the form of anti-vascular endothelial growth factor therapies against neovascular age-related macular degeneration; however, effective treatment is not yet available for geographical atrophy in dry age-related macular degeneration or for preventing the progression from early or mid to the late stage of age-related macular degeneration. Both clinical and experimental investigations involving human age-related macular degeneration retinas and animal models point towards the atrophic alterations in retinal pigment epithelium as a key feature in age-related macular degeneration progression. Retinal pigment epithelium cells are primarily responsible for cellular-structural maintenance and nutrition supply to keep photoreceptors healthy and functional. The retinal pigment epithelium constantly endures a highly oxidative environment that is balanced with a cascade of antioxidant enzyme systems regulated by nuclear factor erythroid-2-related factor 2 as a main redox sensing transcription factor. Aging and accumulated oxidative stress triggers retinal pigment epithelium dysfunction and eventually death. Exposure to both environmental and genetic factors aggravates oxidative stress damage in aging retinal pigment epithelium and accelerates retinal pigment epithelium degeneration in age-related macular degeneration pathophysiology. The present review summarizes the role of oxidative stress in retinal pigment epithelium degeneration, with potential impacts from both genetic and environmental factors in age-related macular degeneration development and progression. Potential strategies to counter retinal pigment epithelium damage and protect the retinal pigment epithelium through enhancing its antioxidant capacity are also discussed, focusing on existing antioxidant nutritional supplementation, and exploring nuclear factor erythroid-2-related factor 2 and its regulators including REV-ERBα as therapeutic targets to protect against age-related macular degeneration development and progression., Competing Interests: None

Circadian rhythm is a 24-hour cycle of behavioral and physiological changes. Disrupted sleep-wake patterns and circadian dysfunction are common in patients of Alzheimer Disease (AD) and are closely related with neuroinflammation. However, it is not well known how circadian rhythm of immune cells is altered during the progress of AD. Previously, we found presenilin 2 ( Psen2 ) N141I mutation, one of familial AD (FAD) risk genes, induces hyperimmunity through the epigenetic repression of REV-ERBα expression in microglia and bone marrow-derived macrophage (BMDM) cells. Here, we investigated whether repression of REV-ERBα is associated with dysfunction of immune cell-endogenous or central circadian rhythm by analyses of clock genes expression and cytokine secretion, bioluminescence recording of rhythmic PER2::LUC expression, and monitoring of animal behavioral rhythm. Psen2 N141I mutation down-regulated REV-ERBα and induced selective over-production of IL-6 (a well-known clock-dependent cytokine) following the treatment of toll-like receptor (TLR) ligands in microglia, astrocytes, and BMDM. Psen2 N141I mutation also lowered amplitude of intrinsic daily oscillation in these immune cells representatives of brain and periphery. Of interest, however, the period of daily rhythm remained intact in immune cells. Furthermore, analyses of the central clock and animal behavioral rhythms revealed that central clock remained normal without down-regulation of REV-ERBα. These results suggest that Psen2 N141I mutation induces hyperimmunity mainly through the suppression of REV-ERBα in immune cells, which have lowered amplitude but normal period of rhythmic oscillation. Furthermore, our data reveal that central circadian clock is not affected by Psen2 N141I mutation.

Brown adipose tissue (BAT) thermogenic functions are primarily mediated by uncoupling protein (UCP)-1. Ucp1 gene expression is highly induced by cold temperature, via sympathetic nervous system and β-adrenergic receptors (βARs). Ucp1 is also repressed by the clock gene Rev-erba, contributing to its circadian rhythmicity. In this study, we investigated mice lacking βARs (β-less mice) to test the relationship between βAR signaling and the BAT molecular clock. We found that in addition to controlling the induction of Ucp1 and other key BAT genes at near freezing temperatures, βARs are essential for the basal expression of BAT Ucp1 at room temperature. Remarkably, although basal Ucp1 expression is low throughout day and night in β-less mice, the circadian rhythmicity of Ucp1 and clock genes in BAT is maintained. Thus, the requirement of βAR signaling for BAT activity is independent of the circadian rhythmicity of Ucp1 expression and circadian oscillation of the molecular clock genes. On the other hand, we found that βARs are essential for the normal circadian rhythms of locomotor activity. Our results demonstrate that in addition to controlling the BAT response to extreme cold, βAR signaling is necessary to maintain basal Ucp1 tone and to couple BAT circadian rhythmicity to the central clock. [ABSTRACT FROM AUTHOR]

In mammals, the suprachiasmatic nucleus (SCN) is the location of a master circadian pacemaker. It receives photic signals from the environment via the retinal hypothalamic tract, which play a key role in synchronizing the body's endogenously generated circadian rhythms with the 24-h rhythm of the environment. Therefore, it is plausible that age-related changes within the SCN contribute to the etiology of perturbed activity- rest cycles that become prevalent in humans during aging. To test this hypothesis, we used gene arrays and quantitative RT-PCR to profile age-related gene expression changes within the SCN of male rhesus macaques - a pragmatic translational animal model of human aging, which similarly displays an age-related attenuation of daytime activity levels. As expected, the SCN showed high expression of arginine vasopressin, vasoactive intestinal polypeptide, calbindin and nuclear receptor subfamily 1, group D, member 1 (NR1D1) (also known as reverse strand of ERBA (REV-ERBα), both at the mRNA and protein level. However, no obvious difference was detected between the SCNs of young (7-12 years) and old animals (21-26 years), in terms of the expression of core clock genes or genes associated with SCN signaling and neurotransmission. These data demonstrate the resilience of the primate SCN to normal aging, at least at the transcriptional level and, at least in males, suggest that age-related disruption of activity-rest cycles in humans may instead stem from changes within other components of the circadian system, such as desynchronization of subordinate oscillators in other parts of the body. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a neurodegenerative disease characterized by progressive degeneration of dopaminergic (DAergic) neurons, particularly in the substantia nigra (SN). Although circadian dysfunction has been suggested as one of the pathophysiological risk factors for PD, the exact molecular link between the circadian clock and PD remains largely unclear. We have recently demonstrated that REV-ERBα, a circadian nuclear receptor, serves as a key molecular link between the circadian and DAergic systems. It competitively cooperates with NURR1, another nuclear receptor required for the optimal development and function of DA neurons, to control DAergic gene transcription. Considering our previous findings, we hypothesize that REV-ERBα may have a role in the onset and/or progression of PD. In the present study, we therefore aimed to elucidate whether genetic abrogation of REV-ERBα affects PD-related phenotypes in a mouse model of PD produced by a unilateral injection of 6-hydroxydopamine (6-OHDA) into the dorsal striatum. REV-ERBα deficiency significantly exacerbated 6-OHDA-induced motor deficits as well as DAergic neuronal loss in the vertebral midbrain including the SN and the ventral tegmental area. The exacerbated DAergic degeneration likely involves neuroinflammation-mediated neurotoxicity. The Rev-erbα knockout mice showed prolonged microglial activation in the SN along with the overproduction of interleukin 1β, a pro-inflammatory cytokine, in response to 6-OHDA. In conclusion, the present study demonstrates for the first time that genetic abrogation of REV-ERBα can increase vulnerability of DAergic neurons to neurotoxic insults, such as 6-OHDA, thereby implying that its normal function may be beneficial for maintaining DAergic neuron populations during PD progression. [ABSTRACT FROM AUTHOR]

BACKGROUND: The orphan nuclear receptors Rev-erbα and Rorα play important roles in lipid metabolism and glucose metabolism. But it is unclear whether they are involved in bone metabolism. OBJECTIVE: To observe the expression of Rev-erbα and Rorα during the osteoblastogenesis process of bone marrow mesenchymal stem cells (BMSCs). METHODS: BMSCs were isolated and purified from C57BL/6 mice by the whole bone marrow adherence method followed by morphology observations and then BMSCs were induced to differentiate into osteoblasts and adipocytes. We detected their differentiation abilities using oil red O staining and alizarin red staining, respectively. Real-time PCR and western blot assay were conducted to detect the mRNA and protein levels of Rev-erbα and Rorα in BMSCs cultured in the osteogenic medium for 0, 7, 14 days. RESULTS AND CONCLUSION: BMSCs from C57BL/6 mice were mainly spindle-shaped and exhibited the swirl-like pattern of growth. Following induction, oil red O staining and alizarin red staining produced a positive reaction in these cells. Rev-erbα expression at both gene and protein levels decreased at 0, 7, 14 days after osteogenic induction, while Rorα expression increased at both gene and protein levels. These findings indicate that Rev-erbα and Rorα may participate in the osteoblastogenesis of BMSCs. [ABSTRACT FROM AUTHOR]

Carboxylesterases (CES) are a family of phase I enzymes that play an important role in xenobiotic clearance and lipid metabolism. Here, we investigate a potential role of E4 promoter-binding protein 4 (E4bp4) in regulation of Ces and CPT-11 (irinotecan, a first-line drug for treating colorectal cancer) pharmacokinetics in mice. Mouse hepatoma Hepa-1c1c7 cells were transfected with Rev-erbα expression plasmid or siRNA targeting E4bp4. The relative mRNA and protein levels of Ces enzymes in the cells or the livers of wild-type and E4bp4-deficient (E4bp4 −/− ) mice were determined by qPCR and Western blotting, respectively. Transcriptional regulation of Ces by E4bp4/Rev-erbα were investigated using luciferase reporter, mobility shift, and co-immunoprecipitation (Co-IP) assays. Pharmacokinetic studies were performed with wild-type and E4bp4 −/− mice after intraperitoneal injection of CPT-11. E4bp4 ablation down-regulated an array of hepatic Ces genes in mice. E4bp4 −/− mice also showed reduced Ces-mediated metabolism and elevated systemic exposure of CPT-11, a well-known Ces substrate. Consistently, E4bp4 knockdown reduced the expression of Ces genes ( Ces2b , Ces2e and Ces2f ) in Hepa-1c1c7 cells. Furthermore, Rev-erbα repressed the transcription of Ces2b, whereas E4bp4 antagonized this repressive action. Co-IP experiment confirmed a direct interaction between E4bp4 and Rev-erbα. Through a combination of promoter analysis and mobility shift assays, we demonstrated that Rev-erbα trans-repressed Ces (Ces2b) through its specific binding to the -767 to-754 bp promoter region. In conclusion, E4bp4 regulates Ces enzymes through inhibition of the transrepression activity of Rev-erbα, thereby impacting the metabolism and pharmacokinetics of Ces substrates. [ABSTRACT FROM AUTHOR]

Background/Aims: Angiotensin II (Ang II) regulates the expression of some core clock genes; excess Ang II leads to atherosclerosis advancement. Macrophage Rev-erbα mediates clockwork and inflammation, and plays a role in atherosclerotic lesion progression. However, the role of Ang II in regulating Rev-erbα expression in macrophages remains unclarified. Methods: We induced THP-1 macrophages by phorbol 12-myristate 13-acetate and investigated the effect of Ang II on Rev-erbα expression via real-time polymerase chain reaction, western blotting and small interfering RNA (siRNA) techniques. The cytotoxicity of the Rev-erbα agonist SR9009 was analyzed using a (3-[4,5-dimethylthiazol-2-yl])-2,5- diphenyltetrazolium bromide assay. Results: Ang II suppressed Rev-erbα mRNA and protein expression in THP-1 macrophages in a dose and time dependent manner. This effect was mediated via Ang II type 1 receptor (AT1R), and not Ang II type 2 receptor or peroxisome proliferator-activated receptor γ (PPARγ). Consistent with Rev-erbα expression regulated by Ang II, the liver X receptor α (LXRα) protein expression was downregulated in a time-dependent manner after Ang II treatment. The activation or silence of LXRα significantly increased or decreased Rev-erbα expression regulated by Ang II, respectively. This suggests that LXRα is involved in the effect of Ang II on Rev-erbα expression. MMP-9 mRNA expressions were significantly suppressed by SR9009 in THP-1 and RAW264.7 macrophages; moreover, SR9009-treatment significantly reduced Ang II–induced MMP-9 protein expressions in two types of macrophages. Conclusion: Ang II downregulates Rev-erbα expression in THP-1 macrophages via the AT1R/LXRα pathway. [ABSTRACT FROM AUTHOR]

REV-ERBα is a nuclear heme receptor, transcriptional repressor and critical component of the molecular clock that drives daily rhythms of metabolism. Evidence reveals that REV-ERBα also plays an important regulatory role in clock-dependent lung physiology and inflammatory responses. We hypothesize that cigarette smoke (CS) exposure influences REV-ERBα abundance in the lungs, facilitating a pro-inflammatory phenotype. To determine the impact of REV-ERBα activation in the CS-induced inflammatory response we treated primary human small airway epithelial cells (SAECs) with CS extract (CSE) or lipopolysaccharide (LPS) in the absence or presence of pre-treatment with the REV-ERBα agonist GSK 4112. We also exposed adult C57BL/6J (WT) and Rev-erbα global KO mice to CS (10 and 30 days) and measured pro-inflammatory cytokine release. Our data reveal that pre-treatment with GSK 4112 reduced CSE/LPS induced pro-inflammatory cytokines release from both SAECs and mouse lung fibroblasts (MLFs). Furthermore, REV-ERBα KO mice show a greater inflammatory response to 10 and 30 days of CS, including increased neutrophil lung influx, pro-inflammatory cytokine (IL-6, MCP-1 and KC) release, and pro-senescence marker (p16) when compared to WT mice. These data demonstrate that REV-ERBα is a critical regulator of CS-induced lung inflammatory responses. [ABSTRACT FROM AUTHOR]

• The expression level of NR1D1 in bladder cancer (BC) is correlated with the prognosis. The patients with negative expression of NR1D1 have shorter DFS than those with NR1D1 positive expression. • Both upregulation of NR1D1 and Rev-erbα agonist SR9009 can suppress the proliferation, migration and colony formation of BC cells in vitro. • Upregulation of NR1D1 can inhibit tumorigenesis in vivo, and proliferation, migration, and invasive biological behaviors in BC, and PI3K/AKT/mTOR signaling pathway may be one of the mechanisms of NR1D1 affecting the biological behavior of BC. To explore the role of circadian clock gene NR1D1 (REV-erbα) in bladder cancer (BC). Firstly, the association of NR1D1 level with clinical characteristics and prognosis was investigated among patients diagnosed with BC. Secondly, CCK-8, transwell, and colony formation experiments were performed among BC cells treated with Rev-erbα agonist (SR9009), as well as lentivirus and siRNA, for which NR1D1 were overexpressed (OE) and knocked down (KD), respectively. Thirdly, cell cycle and apoptosis were tested by flowcytometry. PI3K/AKT/mTOR pathway proteins were determined in OE-NR1D1 cells. Finally, OE-NR1D1 and OE-Control BC cells were subcutaneously implanted in BALB/c nude mice. The tumor size and protein levels were compared between groups. A P < 0.05 was considered as statistically significant. Patients with NR1D1 positive status had a longer disease-free survival than those with negative expression. The cell viability, migration, and colony formation of BC cells after treated with SR9009 were significantly suppressed. OE-NR1D1 cells had obviously inhibited cell viability, migration, and colony formation, while those were found strengthened in KD-NR1D1 cells. Besides, KD-NR1D1 cells were observed with a lower proportion of dead cells and G0/G1 cells, but a higher ratio of G2/M. The changes of p-AKT, p-S6, p-4EBP1, and FASN involved in PI3K/AKT/mTOR pathway were detected in OE- and KD-NR1D1 BC cells. Finally, in vivo data demonstrated that overexpression of NR1D1 suppressed the tumorigenicity of BC cells. NR1D1 played a role of tumor suppressor and it might become a novel target for the treatment of BC. [ABSTRACT FROM AUTHOR]

The nuclear receptor, REV-ERBα, has a key role in circadian rhythms and requires heme as its ligand. The present study determined whether the heme precursor, 5-aminolevulinic acid (ALA), affects REV-ERBα and its target genes. When exposed to ALA, the human lung diploid cell line, WI-38, exhibited activation of REV-ERBα and repression of the transcription of REV-ERBα target genes, including BMAL1, an essential component of the circadian oscillator. Moreover, co-incubation of sodium ferrous citrate (SFC) and ALA also activated REV-ERBα and repressed the transcription of REV-ERBα target genes. These results indicate that ALA regulates human circadian rhythms via REV-ERBα.

The liver is a critical organ of energy metabolism. At least 10% of the liver transcriptome demonstrates rhythmic expression, implying that the circadian clock regulates large programmes of hepatic genes. Here, we review the mechanisms by which this rhythmic regulation is conferred, with a particular focus on the transcription factors whose actions combine to impart liver- and time-specificity to metabolic gene expression.

Proliferation and apoptosis are important physiological processes of preadipocytes. Rev-erbα is a circadian clock gene, and its activity contributes to several physiological processes in various cells. Previous studies demonstrated that Rev-erbα promotes preadipocyte differentiation, but a role of Rev-erbα on preadipocyte proliferation and apoptosis has not been demonstrated. GSK4112 is often used as an agonist of Rev-erbα. In this study, we used GSK4112 to explore the effects of Rev-erbα on preadipocyte proliferation and apoptosis by RT-qPCR, Western blot, Cell Counting Kit-8 (CCK8) measurement, 5-Ethynyl-2′-deoxyuridine (EdU) staining, Annexin V-FITC/PI staining, and flow cytometry. These results revealed that GSK4112 inhibited the viability of 3T3-L1 preadipocytes and decreased cell numbers. There was also decreased expression of the proliferation-related gene Cyclin D and the canonical Wingless-type (Wnt) signaling effect factor β-catenin. Furthermore, palmitate (PA)-inducing cell apoptosis was promoted. Overall, these results reveal that Rev-erbα plays a role in proliferation and palmitate (PA)-inducing apoptosis of 3T3-L1 preadipocytes, and thus may be a new molecular target in efforts to prevent and treat obesity and related disease.

Circadian rhythms are strongly affected by drugs. In rodents, chronic methamphetamine (METH) intake changes circadian activity rhythms, mainly by altering light synchronization that generates the expression of a free-running rhythm with a period longer than 24 h and a second behavioral component that is independent of the main suprachiasmatic (SCN) clock. Although a number of clock genes do not appear to be involved in the effects of METH on circadian behavior, the molecular clockwork controlling these changes is still unclear. Therefore, we investigated the role of the clock gene Rev-Erbα in METH-induced behavioral and molecular responses using knockout mice and their wild-type littermates. Chronic intake of METH alters period circadian behavior of wild-type mice. However, in mice lacking the clock gene Rev-Erbα METH had no effect on their behavioral rhythms. Furthermore, PER2 bioluminescence rhythms in two extra-SCN brain oscillators, the dorsomedial hypothalamus and the habenula, were altered by METH in wild type but not in KO mice. Together, the present results implicate Rev-Erbα in the modulation of the circadian responses to METH and may provide a better comprehension into the mechanisms underlying circadian alterations provoked by drug addiction. [ABSTRACT FROM AUTHOR]

The nuclear receptor Rev-erbβ is a potent transcriptional factor whose functional study has been limited by the lack of suitable antibodies against it. To better understand Rev-erbβ's biological roles, we generated five hybridoma cell lines secreting antibodies against human Rev-erbβ in mice immunized with the purified, prokaryotically expressed recombinant Rev-erbβ-6His fusion protein. Using Western blotting and immunofluorescence analyses, all the five monoclonal antibodies (MAbs) showed strong immunoreactivity to both prokaryotically and eukaryotically expressed recombinant Rev-erbβ. An immunoprecipitation study showed that all five monoclonal antibodies against Rev-erbβ were able to pull down the recombinant Rev-erbβ-Flag protein, but only one of the MAbs against Rev-erbβ, 37H8, could pull down the endogenous Rev-erbβ protein. Furthermore, domain specificity of these MAbs was characterized. Due to the high similarities between Rev-erbα and Rev-erbβ in the C and E domains, those C and E domain-specific anti-Rev-erbβ antibodies can react with human Rev-erbα as well. The MAbs produced in the study will provide a valuable tool for investigating the function of Rev-erbβ. [ABSTRACT FROM AUTHOR]

Mammalian physiology and behavior are regulated by an internal time-keeping system, referred to as circadian rhythm. The circadian timing system has a hierarchical organization composed of the master clock in the suprachiasmatic nucleus (SCN) and local clocks in extra-SCN brain regions and peripheral organs. The circadian clock molecular mechanism involves a network of transcription-translation feedback loops. In addition to the clinical association between circadian rhythm disruption and mood disorders, recent studies have suggested a molecular link between mood regulation and circadian rhythm. Specifically, genetic deletion of the circadian nuclear receptor Rev-erbα induces mania-like behavior caused by increased midbrain dopaminergic (DAergic) tone at dusk. The association between circadian rhythm and emotion-related behaviors can be applied to pathological conditions, including neurodegenerative diseases. In Parkinson’s disease (PD), DAergic neurons in the substantia nigra pars compacta progressively degenerate leading to motor dysfunction. Patients with PD also exhibit non-motor symptoms, including sleep disorder and neuropsychiatric disorders. Thus, it is important to understand the mechanisms that link the molecular circadian clock and brain machinery in the regulation of emotional behaviors and related midbrain DAergic neuronal circuits in healthy and pathological states. This review summarizes the current literature regarding the association between circadian rhythm and mood regulation from a chronobiological perspective, and may provide insight into therapeutic approaches to target psychiatric symptoms in neurodegenerative diseases involving circadian rhythm dysfunction. [ABSTRACT FROM AUTHOR]

The drive to eat is regulated by two compensatory brain pathways termed as homeostatic and hedonic. Hypothalamic orexinergic (ORX) neurons regulate metabolism, feeding and reward, thus controlling physiological and hedonic appetite. Circadian regulation of feeding, metabolism and rhythmic activity of ORX cells are driven by the brain suprachiasmatic clock. How the circadian clock impacts on ORX signalling and feeding-reward rhythms is, however, unknown. Here we used mice lacking the nuclear receptor REV-ERBα, a transcription repressor and a key component of the molecular clockwork, to study food-reward behaviour. Rev-Erbα mutant mice showed highly motivated behaviours to obtain palatable food, an increase in the intake and preference for tasty diets, and in the expression of the ORX protein in the hypothalamus. Palatable food intake was inhibited in animals treated with the ORX1R antagonist. Analyzing the Orx promoter, we found Retinoic acid-related Orphan receptor Response Element binding sites for Rev-Erbα. Furthermore, Rev-Erbα dampened the activation of Orx in vitro and in vivo. Our data provide evidence for a possible repressive role of Rev-Erbα in the regulation of ORX signalling, highlighting an implication of the circadian clockwork in modulating food-reward behaviours with an important impact for the central regulation of overeating. [ABSTRACT FROM AUTHOR]

REV-ERBα (encoded by Nr1d1) is a nuclear receptor that is part of the circadian clock mechanism and regulates metabolism and inflammatory processes. The glucocorticoid receptor (GR, encoded by Nr3c1) influences similar processes, but is not part of the circadian clock, although glucocorticoid signaling affects resetting of the circadian clock in peripheral tissues. Because of their similar impact on physiological processes, we studied the interplay between these two nuclear receptors. We found that REV-ERBα binds to the C-terminal portion and GR to the N-terminal portion of HSP90α and HSP90β, a chaperone responsible for the activation of proteins to ensure survival of a cell. The presence of REV-ERBα influences the stability and nuclear localization of GR by an unknown mechanism, thereby affecting expression of GR target genes, such as IκBα (Nfkbia) and alcohol dehydrogenase 1 (Adh1). Our findings highlight an important interplay between two nuclear receptors that influence the transcriptional potential of each other. This indicates that the transcriptional landscape is strongly dependent on dynamic processes at the protein level. [ABSTRACT FROM AUTHOR]

Aging can modify the morphology and function of the liver, such as generating a decrease in the mitochondria content, autophagy, and cell senescence. Although exercise training has several beneficial effects on hepatic metabolism, its actions on autophagy processes, mitochondrial function, and cellular senescence need to be more widely explored. The present study verified the effects of aging and exercise on hepatic circadian markers, autophagy, and mitochondria activity in 24-month-old mice with a combined exercise training protocol. In addition, we used public datasets from human livers in several conditions and BMAL1 knockout mice. C57BL/6 mice were distributed into Control (CT, young, 6-month-old mice), sedentary old (Old Sed, sedentary, 24-month-old mice), and exercised old (Old Ex, 24-month-old mice submitted to a combined exercise training protocol). The exercise training protocol consisted of three days of endurance exercise – treadmill running, and two days of resistance exercise – climbing a ladder, for three weeks. At the end of the protocol, the liver was removed and prepared for histological analysis, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), immunoblotting technique, and oxygen consumption. Heatmaps were built using a human dataset and Bmal1 knockout samples. In summary, the Old Sed had reduced strength, coordination, and balance, as well as a decrease in Bmal1 expression and the presence of degenerated liver cells. Still, this group upregulated the transcription factors related to mitochondrial biogenesis. The Old Ex group had increased strength, coordination, and balance, improved glucose sensitivity, as well as restored Bmal1 expression and the mitochondrial transcription factors. The human datasets indicated that mitochondrial markers and autophagy strongly correlate with specific liver diseases but not aging. We can speculate that mitochondrial and autophagy molecular markers alterations may depend on long-term training. [ABSTRACT FROM AUTHOR]

Backgrounds: The circadian clock protein Rev-erbα is a crucial regulator of circadian rhythms that affects multiple molecular, cellular, and physiology pathways that control susceptibility, injury, and recovery in the neurological disorders. Emerging evidence suggest that Rev-erbα plays a key role in the inflammation and oxidative stress, two pivotal mechanisms in the pathogenesis, progression, and recovery process of ischemic stroke. However, it remains inconclusive whether Rev-erbα activation is protective against ischemic brain damage. Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, a master regulator of inflammatory and oxidative responses. Our study aimed to determine whether pharmacological activation of Rev-erbα by SR9009 protects against acute ischemic brain damage partly via Nrf2 pathway. Methods: Adult mice were pretreated with SR9009 or Nrf2 inhibitor all-trans-retinoic acid (ATRA) for 3 days prior to Sham or middle cerebral artery occlusion (MCAO) operation. After ischemia for 1 h and reperfusion for 24 h, the neurological function and cerebral infarction volume were determined, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and glutathione peroxidase (GSH-PX) activity in serum were detected by kit. The mRNA and/or protein level of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS), Period (Per)1, Brain and muscle arnt-like1 (Bmal1), Circadian locomotor output cycles kaput (Clock), Rev-erbα, Nrf2, heme oxygenase-1 (HO-1) and quinone oxidoreductase 1 (NQO1) in cerebral cortex were detected by q-PCR and Western blot. Results: We confirmed that SR9009 activated Rev-erbα gene in the cerebral cortex under basal condition. At 24 h after reperfusion, SR9009 ameliorated acute neurological deficits, reduced infarct volume. Meanwhile, the inflammatory TNF-α, IL-1β, iNOS and MDA content levels were significant decreased, SOD and GSH-PX activity were obviously increased, which were markedly blunted (or abolished) by ATRA. SR9009 enhanced the induction of Nrf2 and its downstream target genes HO-1 and NQO1 after ischemic insult. In addition, we found that SR9009 restored Rev-erbα, Bmal1, Clock, Per1 genes expression in the cerebral cortex under ischemic condition. Conclusion: Taken together, Rev-erbα activation by SR9009 protects against ischemic stroke damage, at least, partly through Nrf2 pathway., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Sheng, Chen, Yu, Wu, Kou and Chen.)

The physiological processes of mammals show rhythmic changes in a 24-h cycle. Circadian rhythms are under the subtle control of the autonomous circadian clock, and dysregulation of the circadian system can lead to health problems such as metabolic disorders. REV-ERBα, a member of the nuclear receptor superfamily, is an important component of the mammalian circadian clock. REV-ERBα regulates various physiological processes, including the regulation of metabolism, inflammation and immunity as well as the circadian rhythm, making it a potential therapeutic target for metabolic syndrome, inflammatory diseases and cancers. In recent years, an array of new REV-ERBα ligands have been discovered, most of which have potential applications in the treatment of diseases. In this review, we focus on the regulatory role of nuclear receptor REV-ERBα in energy metabolism and inflammation, in order to provide new strategies for the therapy of metabolic syndrome and its related diseases.

• Rev-erbα knockout mice exhibit both positive and negative mood phenotypes. • Rev-erbα deficiency leads to dysregulation of the dopaminergic and serotonergic systems. • The Rev-erbα gene is required for the regulation of genes essential for neurogenesis in the murine prefrontal cortex. Mood disorders such as depression, anxiety, and bipolar disorder are highly associated with disrupted daily rhythms of activity, which are often observed in shift work and sleep disturbance in humans. Recent studies have proposed the REV-ERBα protein as a key circadian nuclear receptor that links behavioural rhythms to mood regulation. However, how the Rev-erbα gene participates in the regulation of mood remains poorly understood. Here, we show that the regulation of the serotonergic (5-HTergic) system, which plays a central role in stress-induced mood behaviours, is markedly disrupted in Rev-erbα−/− mice. Rev-erbα−/− mice exhibit both negative and positive behavioural phenotypes, including anxiety-like and mania-like behaviours, when subjected to a stressful environment. Importantly, Rev-erbα−/− mice show a significant decrease in the expression of a gene that encodes the rate-limiting enzyme of serotonin (5-HT) synthesis in the raphe nuclei (RN). In addition, 5-HT levels in Rev-erbα−/− mice are significantly reduced in the prefrontal cortex, which receives strong inputs from the RN and controls stress-related behaviours. Our findings indicate that Rev-erbα plays an important role in controlling the 5-HTergic system and thus regulates mood and behaviour. [ABSTRACT FROM AUTHOR]

Hepatocyte nuclear factor 6 (HNF6) is required for liver development, but its role in adult liver metabolism is not known. Here we show that deletion of HNF6 in livers of adult C57Bl/6 mice leads to hepatic steatosis in mice fed normal laboratory chow. Although HNF6 is known mainly as a transcriptional activator, hepatic loss of HNF6 up-regulated many lipogenic genes bound directly by HNF6. Many of these genes are targets of the circadian nuclear receptor Rev-erbα, and binding of Rev-erbα at these sites was lost when HNF6 was ablated in the liver. While HNF6 and Rev-erbα coordinately regulate hepatic lipid metabolism, each factor also affects additional gene sets independently. These findings highlight a novel mechanism of transcriptional repression by HNF6 and demonstrate how overlapping and distinct mechanisms of transcription factor function contribute to the integrated physiology of the liver. [ABSTRACT FROM AUTHOR]

Circadian rhythms, biological oscillations with a period of about 24 h, are maintained by an innate genetically determined time-keeping system called the molecular circadian clockwork. Despite the physiological and clinical importance of the circadian clock, development of small molecule modulators targeting the core clock machinery has only recently been initiated. BMAL1, a core clock gene, is controlled by a ROR/REV-ERB-response element (RORE)-dependent mechanism, which plays an important role in stabilizing the period of the molecular circadian clock. Therefore, we aimed to identify a novel small molecule modulator that regulates Bmal1 gene expression in RORE-dependency, thereby influencing the molecular feedback loop of the circadian clock. For this purpose, we carried out a cell-based screen of more than 1000 drug-like compounds, using a luciferase reporter driven by the proximal region of the mouse Bmal1 promoter. One compound, designated KK-S6, repressed the RORE-dependent transcriptional activity of the m Bmal1 promoter and reduced endogenous BMAL1 protein expression. More importantly, KK-S6 significantly altered the amplitude of circadian oscillations of Bmal1 and Per2 promoter activities in a dose-dependent manner, but barely affected the period length. KK-S6 effectively decreased mRNA expression of metabolic genes acting downstream of REV-ERBα, Pai-1 and Citrate synthase, that contain RORE cis -element in their promoter. KK-S6 likely acts in a RORE-dependent manner by reinforcing the REV-ERBα activity, though not by the same mechanism as known REV-ERB agonists. In conclusion, the present study demonstrates that KK-S6 functions as a novel modulator of the amplitude of molecular circadian rhythms by influencing RORE-mediated BMAL1 expression. [ABSTRACT FROM AUTHOR]

Disrupted daily or circadian rhythms of lung function and inflammatory responses are common features of chronic airway diseases. At the molecular level these circadian rhythms depend on the activity of an autoregulatory feedback loop oscillator of clock gene transcription factors, including the BMAL1:CLOCK activator complex and the repressors PERIOD and CRYPTOCHROME. The key nuclear receptors and transcription factors REV-ERBα and RORα regulate Bmal1 expression and provide stability to the oscillator. Circadian clock dysfunction is implicated in both immune and inflammatory responses to environmental, inflammatory, and infectious agents. Molecular clock function is altered by exposomes, tobacco smoke, lipopolysaccharide, hyperoxia, allergens, bleomycin, as well as bacterial and viral infections. The deacetylase Sirtuin 1 (SIRT1) regulates the timing of the clock through acetylation of BMAL1 and PER2 and controls the clock-dependent functions, which can also be affected by environmental stressors. Environmental agents and redox modulation may alter the levels of REV-ERBα and RORα in lung tissue in association with a heightened DNA damage response, cellular senescence, and inflammation. A reciprocal relationship exists between the molecular clock and immune/inflammatory responses in the lungs. Molecular clock function in lung cells may be used as a biomarker of disease severity and exacerbations or for assessing the efficacy of chronotherapy for disease management. Here, we provide a comprehensive overview of clock-controlled cellular and molecular functions in the lungs and highlight the repercussions of clock disruption on the pathophysiology of chronic airway diseases and their exacerbations. Furthermore, we highlight the potential for the molecular clock as a novel chronopharmacological target for the management of lung pathophysiology. [ABSTRACT FROM AUTHOR]