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• Macrophage-mediated inflammation plays a critical role in Acute-on-chronic liver failure (ACLF). • Knockdown of RNA-binding protein IGF2BP3 potentially confers hepatoprotection by mitigating macrophage-induced inflammation. • RORα is a target protein of IGF2BP3, its depletion increase liver damage and inflammation by modulating the NF-κB pathway. • These discoveries offer novel insights into the pathogenesis and potential therapeutic targets for ACLF. Acute-on-chronic liver failure (ACLF) is a severe condition characterized by high mortality rates, and macrophage-mediated inflammation plays a critical role in its progression. Our previous research has indicated the involvement of the RNA-binding protein IGF2BP3 in the pathogenesis of ACLF. However, the underlying molecular mechanisms contributing to this damage require further elucidation. Initially, we observed heightened expression of pro-inflammatory cytokines and macrophage activation in both ACLF patients and a mouse model induced by D-GalN/LPS. Subsequent loss-of-function experiments targeting IGF2BP3 revealed that the knockdown of IGF2BP3 potentially confers hepatoprotection by mitigating macrophage-induced inflammation. Further investigation using RNA Immunoprecipitation (RIP) assays and dual luciferase reporter assays confirmed that RORα is a target protein of the RNA-binding protein IGF2BP3. Importantly, depletion of RORα was found to significantly increase liver damage and inflammation by modulating the NF-κB signaling pathway. In conclusion, our findings underscore the crucial role of IGF2BP3 in mediating liver damage induced by activated macrophages in ACLF, which is regulated by the RORα-NF-κB signaling pathway. These discoveries offer novel insights into the pathogenesis and potential therapeutic targets for ACLF. [ABSTRACT FROM AUTHOR]

Innate lymphoid cells (ILCs), strategically positioned throughout the body, undergo population declines over time. A solution to counteract this problem is timely mobilization of multipotential progenitors from the bone marrow. It remains unknown what triggers the mobilization of bone marrow ILC progenitors (ILCPs). We report that ILCPs are regulated by the circadian clock to emigrate and generate mature ILCs in the periphery. We found that circadian-clock-defective ILCPs fail to normally emigrate and generate ILCs. We identified circadian-clock-controlled endocrine and cytokine cues that, respectively, regulate the retention and emigration of ILCPs at distinct times of each day. Activation of the stress-hormone-sensing glucocorticoid receptor upregulates CXCR4 on ILCPs for their retention in the bone marrow, while the interleukin-18 (IL-18) and RORα signals upregulate S1PR1 on ILCPs for their mobilization to the periphery. Our findings establish important roles of circadian signals for the homeostatic efflux of bone marrow ILCPs. [Display omitted] • Emigration of bone marrow ILCPs is dependent on zeitgeber times • Circadian signals differentially regulate the efflux of bone marrow ILCPs • IL-18 and glucocorticoid signals distinctly regulate S1PR1 or CXCR4 Liu et al. report that common ILC progenitors in the bone marrow highly express genes that regulate the circadian clock and that the mobilization of these progenitors from the bone marrow occurs in a circadian-clock-dependent manner. Mechanistically, circadian signals regulate the bone marrow retention and emigration receptors for these ILC progenitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Decrease in the amount of RORα is observed in Purkinje cells of SCA1 and SCA3 model mice. • AAV vectors were used to knock-down RORα specifically in mature Purkinje cells in vivo. • The RORα knock-down caused Purkinje cell dendrite atrophy and disruption of the cell layer. • RORα-knock-down mice showed motor learning deficits and, later, overt cerebellar ataxia. • Decrease in RORα expression in Purkinje cells could be a primary etiology of cerebellar symptoms in SCAs. Retinoid-related orphan receptor α (RORα) is a transcription factor expressed in a variety of tissues throughout the body. Knockout of RORα leads to various impairments, including defects in cerebellar development, circadian rhythm, lipid metabolism, immune function, and bone development. Previous studies have shown significant reduction of RORα expression in Purkinje cells (PCs) of spinocerebellar ataxia (SCA) type 1 and type 3/MJD (Machado–Joseph disease) model mice. However, it remains unclear to what extent the RORα reduction in PCs is involved in the disease pathology. Here, RORα expression was downregulated specifically in mature mouse PCs by intravenous infusion of blood–brain barrier-permeable adeno-associated virus (AAV), expressing a microRNA against RORα (miR-RORα) under the control of the PC-specific L7-6 promoter. The systemic AAV infusion led to extensive transduction of PCs. The RORα knock-down caused degeneration of PCs including disruption of the PC monolayer alignment and dendrite atrophy. In behavioral experiments, mice expressing miR-RORα showed motor learning deficits, and later, overt cerebellar ataxia. Thus, RORα in mature PCs plays pivotal roles in maintenance of PC dendrites and the monolayer alignment, and consequently, motor learning and motor function. Decrease in RORα expression in PCs could be a primary etiology of the cerebellar symptoms in patients with SCA1 and SCA3/MJD. [ABSTRACT FROM AUTHOR]

• Bdnf and Trkb expression display a daily variation. • Daily rhythms of Apo E protein are observed in the rat temporal cortex. • BMAL1 and RORα levels vary rhythmically in this brain area. • An i.c.v injection of aggregated Aβ (1-42) modifies those temporal patterns. Alzheimer's disease (AD) is a devastating disease characterized by loss of synapses and neurons in the elderly. Accumulation of the β-amyloid peptide (Aβ) in the brain is thought to be central to the pathogenesis of AD. ApoE plays a key role in normal and physiological clearance of Aß, since it facilitates the peptide intra- and extracellular proteolytic degradation. Besides the cognitive deficit, AD patients also show alterations in their circadian rhythms. The objective of this study was to investigate the effects of an i.c.v. injection of Aβ (1-42) peptide on the 24 h rhythms of Apo E, BMAL1, RORα, Bdnf and trkB mRNA and Aβ levels in the rat temporal cortex. We found that an i.c.v. injection of Aβ aggregates phase shifts daily Bdnf expression as well as Apo E, BMAL1, RORα, Aβ and decreased the mesor of TrkB rhythms. Thus, elevated Aβ peptide levels might modify the temporal patterns of cognition-related factors, probably; by affecting the clock factors rhythms as well as in the 24 h rhythms of Apo E. [ABSTRACT FROM AUTHOR]

Hepatic fibrosis is a dynamic process characterized by the net accumulation of an extracellular matrix resulting from chronic liver injury such as nonalcoholic steatohepatitis. Activation of hepatic stellate cells (HSCs) plays a role in transdifferentiation of quiescent cells into fibrogenic myofibroblasts. We aimed to examine the function of retinoic acid receptor-related orphan receptor alpha (RORα) and its novel agonistic ligand, 1-(4-benzyloxybenzyl)-3-(2-dimethylaminoethyl)-thiourea (ODH-08) against activation of HSCs using hepatic fibrosis mouse models. Chemical synthesis, a reporter gene assay, surface plasmon resonance analysis, and a docking study were performed to evaluate ODH-08 as a ligand of RORα. In vivo experiments with mice fed a Western diet were performed to evaluate the effect of ODH-08. The human HSC line, Lx-2, and primary mouse HSCs were employed to identify the molecular mechanisms underlying the antifibrogenic effect of ODH-08. A novel RORα-selective ligand, ODH-08, was developed based on modification of JC1-40, an analog of N -methylthiourea. Administration of ODH-08 to the Western diet-fed mice reduced hepatic collagen deposition and expression levels of fibrogenic markers such as α-smooth muscle actin and collagen type I alpha 1 chain. Activation of RORα—either by transient overexpression of RORα or treatment with ODH-08—suppressed the expression of fibrogenic proteins in HSCs. The activation of RORα suppressed the activity of SMAD2 and 3, which are the primary downstream proteins of transforming growth factor β. RORα and its agonist ODH-08 have a potent antifibrotic effect, which could provide a novel antifibrotic strategy against hepatic fibrosis. [ABSTRACT FROM AUTHOR]

Type 1 innate lymphoid cells (ILC1s) possess adaptive immune features, which confer antigen-specific memory responses against haptens and viruses. However, the transcriptional regulation of memory ILC1 responses is currently not known. We show that retinoic acid receptor-related orphan receptor alpha (RORα) has high expression in memory ILC1s in murine contact hypersensitivity (CHS) models. RORα deficiency diminishes ILC1-mediated CHS responses significantly but has no effect on memory T cell-mediated CHS responses. During sensitization, RORα promotes sensitized-ILC1 expansion by suppressing expression of cell-cycle repressors in draining lymph nodes. RORα programs gene-expression patterns related to cell survival and is required for the long-term maintenance of memory ILC1s in the liver. Our findings reveal RORα to be a key transcriptional factor for sensitized-ILC1 expansion and long-term maintenance of memory ILC1s. [Display omitted] • Transcription factor RORα is essential for ILC1-mediated memory responses • RORα promotes hapten-induced ILC1 expansion in draining lymph nodes • RORα is required for long-term maintenance of memory ILC1s in the liver • RORα is dispensable for memory ILC1 recall responses upon secondary challenge Liver ILC1s can mediate memory response against haptens and viruses. Cheng et al. show critical roles of transcription factor RORα for memory ILC1 formation and long-term maintenance. RORα deficiency leads to a defect in ILC1 expansion in the lymph nodes after hapten sensitization as well as impaired long-term survival of memory ILC1s in the liver. [ABSTRACT FROM AUTHOR]

• RL promotes melatonin nuclear receptor RORα expression in chick thymus relative to GL. • RORα plays a negative role in the process of GL-induced T-lymphocyte proliferation. • RORα promotes NF-κB nuclear translocation through upregulating IκB phosphorylation. Present study clarified role of melatonin nuclear receptor RORα in monochromatic light-induced T-lymphocyte proliferation in chicks. Green light elevated plasma melatonin level and organ index, T-lymphocyte proliferation and IL-2 production in thymus, but decreased RORα, p-P65 and p-IκB expressions relative to red light. By contrast, pinealectomy decreased the melatonin content and reversed the stimulatory effect of green light, and resulted in that these thymus parameters were not significantly different among the light-treated groups. Exogenous melatonin supplementation enhanced T-lymphocyte proliferation and IL-2 production in cultured thymocytes. This stimulatory effect of melatonin was reversed by RORα agonist but was enhanced by RORα antagonist. In contrast to RORα antagonist, RORα agonist decreased cytoplasmic P65 level and increased nuclear P65 level. Supplementation with P65 antagonist increased T-lymphocyte proliferation. We conclude that RORα could negatively regulate green light-enhanced T-lymphocyte proliferation in chick thymus by upregulating IκB phosphorylation, which promotes P65 nuclear translocation and NF-κB activation. [ABSTRACT FROM AUTHOR]

Abstract Objectives The nuclear receptor superfamily is a potential target for the development of new treatments for obesity and metabolic diseases. Increasing evidence has pointed towards the retinoic acid-related orphan receptor-alpha (RORα) as an important nuclear receptor involved in several biological processes. RORα full body knockout mice display improved metabolic phenotypes on both chow and high fat (60% fat, 20% carbohydrate) diets, but also have severe behavioral abnormalities. Here we investigated the effect of hepatic RORα by generating mice with liver-specific RORα deletion to elucidate the role of this nuclear receptor on host metabolism. Methods 8 week-old mice with liver-specific RORα deletion and littermate controls were fed either chow or western-style diets (40% fat, 40% carbohydrate) for 12 weeks. Metabolic phenotyping was performed at the end of the dietary intervention. Results Here, we show that hepatic RORα deletion does not affect the metabolic susceptibility to either chow or western-style diet in terms of glucose metabolism and adiposity. Conclusions Our data indicate that liver deletion of RORα does not have a pivotal role in the regulation of hepatic glucose and lipid metabolism on chow or western-style diet. Highlights • Hepatic deletion of RORα does not affect host metabolism on chow diet. • Hepatic deletion of RORα does not affect host metabolism on western-style diet. • Similar phenotypes between male and female mice. [ABSTRACT FROM AUTHOR]

Abstract Retinoic acid receptor-related orphan receptor (ROR) α has been implicated in various physiological functions, including the immune system, inflammation, and circadian rhythms. In the present study, the synthetic RORα/γ agonist SR1078 stimulated the production and gene expression of fibroblast growth factor 21 (FGF21) in C2C12 myotubes. FGF21, a member of the FGF family, plays important roles in the regulation of peripheral glucose tolerance and lipid metabolism and improves metabolic health. The mRNA expression and secretion of FGF21 was significantly weaker in Rora -silenced cells than in cells transfected with non-targeting control siRNA. SR1078 significantly up-regulated C/EBP homologous protein (CHOP), an established marker of ER stress, in a dose-dependent manner in C2C12 myotubes, while CHOP expression was decreased in Rora -silenced C2C12 cells, suggesting that RORα is involved in the regulation of FGF21 expression and stimulates ER stress in C2C12 myotubes. The naturally occurring compound baicalein up-regulated FGF21 expression and secretion in C2C12 myotubes. Additionally, the up-regulation of CHOP mRNA and protein expression was observed in C2C12 myotubes after the baicalein treatment. Furthermore, the knockdown of RORα prevented the augmentation of FGF21 and up-regulation of CHOP in response to baicalein in C2C12 cells. Collectively, these results suggest that baicalein stimulates the ER stress response and FGF21 expression through an RORα-dependent mechanism in C2C12 myotubes, and indicate the potential of baicalein as an effective anti-obesity therapy via its ability to enhance FGF21 production. [ABSTRACT FROM AUTHOR]

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with a rising prevalence in boys rather than girls. G protein-coupled estrogen receptor (GPER) activation by its agonist G1 showed a neuroprotective effect, similar to estradiol. The present study aimed to examine the potential of the selective GPER agonist G1 therapy on the behavioral, histopathological, biochemical, and molecular alterations induced in a valproic acid (VPA)-rat model of autism. VPA (500 mg/kg) was intraperitoneally administered to female Wistar rats (on gestational day 12.5) to induce the VPA-rat model of autism. The male offspring were intraperitoneally administered with G1 (10 and 20 μg/kg) for 21 days. After the treatment process, rats performed behavioral assessments. Then, sera and hippocampi were collected for biochemical and histopathological examinations and gene expression analysis. GPER agonist G1 attenuated behavioral deficits, including hyperactivity, declined spatial memory and social preferences, anxiety, and repetitive behavior in VPA rats. G1 improved neurotransmission and reduced oxidative stress and histological alteration in the hippocampus. G1 reduced serum free T levels and interleukin-1β and up-regulated GPER, RORα, and aromatase gene expression levels in the hippocampus. The present study suggests that activation of GPER by its selective agonist G1 altered the derangements induced in a VPA-rat model of autism. G1 normalized free T levels via up-regulation of hippocampal RORα and aromatase gene expression. G1 provoked estradiol neuroprotective functions via up-regulation of hippocampal GPER expression. The G1 treatment and GPER activation provide a promising therapeutic approach to counteract the autistic-like symptoms. [Display omitted] • GPER selective agonist G1 attenuated behavioral and hippocampal neurotransmission impairments in the VPA-rat model of autism. • GPER selective agonist G1 normalized free T levels via up-regulation of hippocampal RORα and aromatase gene expression. • G1 provoked estradiol neuroprotective functions via up-regulation of hippocampal GPER expression. • We suggest that GPER activation by G1 provides a promising therapeutic approach to counteract autistic-like symptoms. [ABSTRACT FROM AUTHOR]

Intervertebral disc degeneration (IDD) is associated with low back pain, yet its inherent mechanism remains obscure. Hypercholesteremia was regarded as a risk factor for IDD, and our previous study showed that cholesterol accumulation could elicit matrix degradation in the nucleus pulposus (NP). MicroRNA-155 (miR-155) was substantiated as protective in IDD, but its role in cholesterol-induced IDD was unclear. The present study investigated whether miR-155 could mediate cholesterol-related IDD and its internal mechanisms. In vivo experiments revealed high-fat diet-induced hypercholesteremia in wild-type (WT) mice along with the occurrence of IDD, whereas Rm155LG transgenic mice showed milder NP degeneration, as evidenced by Saffron O-fast green (SF) staining and immunohistochemistry (IHC). Meanwhile, IHC showed that NLRP3 and Bax expression was also suppressed in Rm155LG mice. In vitro studies using Western blotting (WB) and immunofluorescence (IF) confirmed that the miR-155 mimic could alleviate cholesterol-induced matrix degradation, apoptosis and pyroptosis in NP. Moreover, RORα was upregulated in severely degenerated NP compared to mild IDD. It was also noted that RORα was suppressed in Rm155LG mice. In this study, we demonstrated that miR-155 could target RORα and that inhibition of RORα could prevent cholesterol-induced matrix degradation, apoptosis, and pyroptosis in NP, indicating the protective effect of miR-155 in cholesterol-induced IDD by targeting RORα. • High-fat diet induced intervertebral disc degeneration and miR-155 rescued this effect. • Cholesterol induced extracellular matrix degradation, apoptosis and pyroptosis. • miR-155 abrogated cholesterol-induced extracellular matrix degradation, apoptosis and pyroptosis. • RORα increased in degenerative NP tissue and was positively regulated by cholesterol. • miR-155 alleviated intervertebral disc degeneration by binding to RORα. [ABSTRACT FROM AUTHOR]

The classical pathway of vitamin D activation follows the sequence D3 → 25(OH)D3 → 1,25(OH) 2 D3 with the final product acting on the receptor for vitamin D (VDR). An alternative pathway can be started by the action of CYP11A1 on the side chain of D3, primarily producing 20(OH)D3, 22(OH)D3, 20,23(OH) 2 D3, 20,22(OH) 2 D3 and 17,20,23(OH) 3 D3. Some of these metabolites are hydroxylated by CYP27B1 at C1α, by CYP24A1 at C24 and C25, and by CYP27A1 at C25 and C26. The products of these pathways are biologically active. In the epidermis and/or serum or adrenals we detected 20(OH)D3, 22(OH)D3, 20,22(OH) 2 D3, 20,23(OH) 2 D3, 17,20,23(OH) 3 D3, 1,20(OH) 2 D3, 1,20,23(OH) 3 D3, 1,20,22(OH) 3 D3, 20,24(OH) 2 D3, 1,20,24(OH) 3 D3, 20,25(OH) 2 D3, 1,20,25(OH) 3 D3, 20,26(OH) 2 D3 and 1,20,26(OH) 3 D3. 20(OH)D3 and 20,23(OH) 2 D3 are non-calcemic, while the addition of an OH at C1α confers some calcemic activity. Molecular modeling and functional assays show that the major products of the pathway can act as “biased” agonists for the VDR with high docking scores to the ligand binding domain (LBD), but lower than that of 1,25(OH) 2 D3. Importantly, cell based functional receptor studies and molecular modeling have identified the novel secosteroids as inverse agonists of both RORα and RORγ receptors. Specifically, they have high docking scores using crystal structures of RORα and RORγ LBDs. Furthermore, 20(OH)D3 and 20,23(OH) 2 D3 have been tested in a cell model that expresses a Tet-on RORα or RORγ vector and a RORE-LUC reporter (ROR-responsive element), and in a mammalian 2-hybrid model that test interactions between an LBD-interacting LXXLL-peptide and the LBD of RORα/γ. These assays demonstrated that the novel secosteroids have ROR-antagonist activities that were further confirmed by the inhibition of IL17 promoter activity in cells overexpressing RORα/γ. In conclusion, endogenously produced novel D3 hydroxy-derivatives can act both as “biased” agonists of the VDR and/or inverse agonists of RORα/γ. We suggest that the identification of large number of endogenously produced alternative hydroxy-metabolites of D3 that are biologically active, and of possible alternative receptors, may offer an explanation for the pleiotropic and diverse activities of vitamin D, previously assigned solely to 1,25(OH) 2 D3 and VDR. [ABSTRACT FROM AUTHOR]

Retinoid-related orphan receptor α (RORα), a member of the metabolic nuclear receptor superfamily, plays a vital regulatory role in circadian rhythm and metabolism. Here, we investigated the role of RORα in high-fat diet (HFD)-induced cardiac impairments and the underlying mechanisms involved. RORα-deficient stagger mice (sg/sg) and wild type (WT) littermates were fed with either standard diet or HFD. At 20 weeks after HFD treatment, RORα deficiency resulted in significantly decreased body weight gain, improved dyslipidemia and ameliorated insulin resistance (evaluated by blood biochemical and glucose/insulin tolerance tests) compared with WT control. However, compared with HFD-treated WT mice, HFD-treated sg/sg mice exhibited significantly augmented myocardial hypertrophy, cardiac fibrosis (wheat germ agglutinin, masson trichrome and sirius red staining) and cardiac dysfunction (echocardiography and hemodynamics). Mechanistically, RORα deficiency impaired mitochondrial biogenesis and function. Additionally, RORα deficiency resulted in inhibition of the AMPK-PGC1α signaling pathway. In contrast, cardiomyocyte-specific RORα overexpression ameliorated myocardial hypertrophy, fibrosis and dysfunction by restoring AMPK-PGC1α signaling, and subsequently normalizing mitochondrial biogenesis. These findings demonstrated for the first time that nuclear receptor RORα deficiency aggravated HFD-induced myocardial dysfunction at least in part by impairing mitochondrial biogenesis in association with disrupting AMPK-PGC1α signaling. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren and Megan Yingmei Zhang. [ABSTRACT FROM AUTHOR]

Summary The regulation of M1/M2 polarization in liver macrophages is closely associated with the progression of nonalcoholic steatohepatitis (NASH); however, the mechanism involved in this process remains unclear. Here, we describe the orphan nuclear receptor retinoic-acid-related orphan receptor α (RORα) as a key regulator of M1/M2 polarization in hepatic residential Kupffer cells (KCs) and infiltrated monocyte-derived macrophages. RORα enhanced M2 polarization in KCs by inducing the kruppel-like factor 4. M2 polarization was defective in KCs and bone-marrow-derived macrophages of the myeloid-specific RORα null mice, and these mice were susceptible to HFD-induced NASH. We found that IL-10 played an important role in connecting the function of M2 KCs to lipid accumulation and apoptosis in hepatocytes. Importantly, M2 polarization was controlled by a RORα activator, JC1-40, which improved symptoms of NASH. Our results suggest that the M2-promoting effects of RORα in liver macrophages may provide better therapeutic strategies against NASH. [ABSTRACT FROM AUTHOR]

Summary The mammalian circadian system consists of a master clock in the brain that synchronizes subsidiary oscillators in peripheral tissues. The master clock maintains phase coherence in peripheral cells through systemic cues such as feeding-fasting and temperature cycles. Here, we examined the role of oxygen as a resetting cue for circadian clocks. We continuously measured oxygen levels in living animals and detected daily rhythms in tissue oxygenation. Oxygen cycles, within the physiological range, were sufficient to synchronize cellular clocks in a HIF1α-dependent manner. Furthermore, several clock genes responded to changes in oxygen levels through HIF1α. Finally, we found that a moderate reduction in oxygen levels for a short period accelerates the adaptation of wild-type but not of HIF1α-deficient mice to the new time in a jet lag protocol. We conclude that oxygen, via HIF1α activation, is a resetting cue for circadian clocks and propose oxygen modulation as therapy for jet lag. [ABSTRACT FROM AUTHOR]

Macrophages are able to polarize to pro-inflammatory M1 or anti-inflammatory M2 states with distinct phenotypes and physiological functions. RORα is a member of the nuclear receptor super family and plays important roles in lipid, glucose metabolism, as well as the inflammatory response. In this study, we examined the potential function of RORα in the regulation of macrophage polarization. Treatment of RAW264.7 macrophages with RORα agonist cholesterol sulfate (CH-S) and overexpression of RORα increased M2 macrophage markers expressions (Arg1, Ym1 and Fizz1) both on mRNA and protein levels. Conversely, selective antagonism (SR1001) abrogated the induction of M2 macrophage markers which induced by CH-S. In addition, CH-S induced phosphorylation of Adenosine monophosphate (AMP)-activated protein kinase α (AMPKα), which was accompanied by the activation of acetyl-CoA carboxylase 1 (ACC). However, SR1001 abolished the activation of AMPKα and ACC induced by CH-S. Meanwhile, inactivation of AMPKα by its inhibitor Compound C (Comp C) abrogated the mRNA and protein levels of CH-S-induced M2 macrophage markers expressions. Together these findings reveal that RORα regulates macrophage M2 polarization via activation of AMPKα, which may provide a novel beneficial effect of RORα against inflammation. [ABSTRACT FROM AUTHOR]

The RAR-related orphan receptors (RORs) are members of the nuclear receptor family of intracellular transcription factors. In this study, we examined the regulatory properties of RORα (CsRORα) and RORγ (CsRORγ) in tongue sole ( Cynoglossus semilaevis ). CsRORα and CsRORγ expression was detected in major lymphoid organs and altered to significant extents after bacterial and viral infection. CsRORα enhanced the activities of CsIL-17C, CsIL-17D, and CsIL-17F promoters, which contain CsRORα and CsRORγ binding sites. CsRORγ also upregulated the promoter activities of CsIL-17D and CsIL-17F but not CsIL-17C. CsRORα and CsRORγ proteins were detected in the nucleus, and overexpression of CsRORα in tongue sole significantly increased the expression of CsIL-17C, CsIL-17D, and CsIL-17F, whereas overexpression of CsRORγ significantly increased the expression of CsIL-17C and CsIL-17F but no CsIL-17D. These results indicate that RORα and RORγ in teleost regulate the expression of IL-17 members in different manners. [ABSTRACT FROM AUTHOR]

Fasting hormones activate the cAMP/PKA signaling pathway and stimulate expression of hepatic gluconeogenic enzymes including glucose-6-phosphatase (G6Pase). Previously it was shown that steroid receptor coactivator 2 (SRC-2) knock-out mice exhibit fasting hypoglycemia and that SRC-2 coactivates RAR-related orphan receptor alpha (RORα) at the proximal G6Pase promoter. We have investigated the upstream regulation and functional implications of this RORα/SRC-2 complex on G6Pase expression. In HepG2 cells, overexpression of the catalytic PKA subunit (PKA-Cα) reduced the SRC-2 protein level, recruitment to the G6Pase promoter, and its ability to coactivate RORα. Knock-down and transactivation experiments employing G6Pase promoter constructs demonstrated that RORα and SRC-2 are required for PGC-1α to stimulate G6Pase expression. These results suggest that PKA inhibits SRC-2 coactivation of RORα and in turn reduces PGC-1α dependent regulation of G6Pase. This indirect feedback mechanism may underlie the suppression of gluconeogenesis throughout long-term starvation. [ABSTRACT FROM AUTHOR]

Proanthocyanidins (PAs), a flavonoid sub-class, alter the expression of clock genes in the liver of lean and obese rats. The present study aimed to determine whether PAs could modulate the 24-hour rhythmicity of clock gene expression and to identify the molecular mechanism through which PAs could adjust the clock system in HepG2 cells. The 24-hour rhythmicity of core clock ( CLOCK and BMAL1 ) and clock-controlled ( CRY, PER2, RORα, REV-ERBα ) gene expression indicated that a grape seed proanthocyanidin extract (GSPE) shifted the acrophase of nearly all of them, but BMAL1 appeared as the most sensitive gene to GSPE. Specifically, GSPE increased BMAL1 expression strongly and very quickly. This effect was also reproduced by melatonin. The overexpression of BMAL1 was melatonin receptor 1 (MT1) dependent for melatonin but MT1 independent for GSPE. However, GSPE increased the transcriptional activity of RORα, suggesting that this nuclear receptor could be responsible for the modulation of BMAL1 by GSPE. [ABSTRACT FROM AUTHOR]

Circadian rhythm plays an important role in maintaining homeostasis, and its disruption increases the risk of developing metabolic syndrome. Circadian rhythm is maintained by a central clock in the hypothalamus that is entrained by light, but circadian clocks are also present in peripheral tissues. These peripheral clocks are trained by other cues, such as diet. The aim of this study was to determine whether proanthocyanidins, the most abundant polyphenols in the human diet, modulate the expression of clock and clock-controlled genes in the liver, gut and mesenteric white adipose tissue (mWAT) in healthy and obese rats. Grape seed proanthocyanidin extracts (GSPEs) were administered for 21 days at 5, 25 or 50 mg GSPE/kg body weight in healthy rats and 25 mg GSPE/kg body weight in rats with diet-induced obesity. In healthy animals, GSPE administration led to the overexpression of core clock genes in a positive dose-dependent manner. Moreover, the acetylated BMAL1 protein ratio increased with the same pattern in the liver and mWAT. With regards to clock-controlled genes, Per2 was also overexpressed, whereas Rev-erbα and RORα were repressed in a negative dose-dependent manner. Diet-induced obesity always resulted in the overexpression of some core clock and clock-related genes, although the particular gene affected was tissue specific. GSPE administration counteracted disturbances in the clock genes in the liver and gut but was less effective in normalizing the clock gene disruption in WAT. In conclusion, proanthocyanidins have the capacity to modulate peripheral molecular clocks in both healthy and obese states. [ABSTRACT FROM AUTHOR]

Background Retinoic acid-related orphan receptor α (RORα) has been implicated in the progression of atherosclerosis, but its role in the proliferation of vascular smooth muscle cells (vSMCs) has not been fully examined. We previously reported that RORα activates AMP-activated protein kinase (AMPK), which is associated with the suppression of vSMC proliferation. Therefore, we investigated the suppressive function of RORα on the proliferation of vSMCs and the molecular mechanisms involved. Results First, RORα and its activator, cholesterol sulfate (CS), induced the activation of AMPK in both human aortic SMCs and rat A7r5 cells, which was accompanied by the suppression of mammalian target of rapamycin (mTOR) and p70 ribosomal protein S6 kinase 1. Second, RORα and CS modulated the expression of cell-cycle-regulating factors, such as p53, p27, and cyclin D in vSMCs. Consistent with this, the overexpression of RORα or CS treatment suppressed the proliferation of human aortic SMCs and rat A7r5 cells, possibly through G 1 arrest. RORα and CS also inhibited the migration of A7r5 cells in two-dimensional and three-dimensional cell migration assays. Finally, we demonstrated that the infusion of adenovirus encoding RORα into arteries suppressed neointima formation after balloon injury in rats. Conclusion These results demonstrate that RORα inhibits vSMC proliferation through AMPK-induced mTOR suppression, and suggest that RORα is a therapeutic target for the cardiovascular diseases associated with vSMC proliferation. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is the most common form of dementia characterized by a gradual impairment in cognitive functions. Recent research have shown that TNF-α is a proinflammatory cytokine implicated in the pathogenesis of neurodegenerative diseases, such as AD. Besides cognitive deficit, AD patients show alterations in their circadian rhythms. The objective of this work was to investigate the effects of an intracerebroventricular injection of Aß aggregates on temporal patterns of cognitive functions and on daily rhythms of Aβ, TNFα, BMAL1 and RORα protein levels in the rat prefrontal cortex. Four-month-old males Holtzman rats were used in this study. Groups were defined as: control and Aβ-injected rats. Rats were maintained under 12h-light:12h-dark throughout the entire experimental period. Prefrontal cortex samples were isolated every 4 h during a 24h period. Our results demonstrated that an intracerebroventricular injection of Aß aggregates impaired learning and memory in rats at ZT 2 and ZT 14 and modified daily patterns of Aβ, TNFα, and clock-related factors in the rat prefrontal cortex. Our findings showed that the increase of Aß altered temporal patterns of TNFα, and, consequently, induced alterations in daily rhythms of clock-related factors, affecting the cognitive performance of animals with Alzheimer's. • Daily rhythms of TNFα and clock-related factors are observed in the rat prefrontal cortex. • Temporal patterns of cognitive functions are found in this brain area. • An injection of Aβ aggregates phase shifted daily rhythms of TNFα, BMAL1 and RORα. • The Aβ group showed alterations in cognitive functions. [ABSTRACT FROM AUTHOR]

Abstract: The wild animals are exposed in nature to more oxidative stress than any laboratory animals. Studies on oxidative stress of brain, liver and kidney are quite common while very less reports are available on respiratory system when it is the most susceptible organ to various stressors. We checked the oxidative stress of lung tissue of a wild seasonally breeding bird Perdicula asiatica by noting down the daily variation in antioxidant enzymes (superoxide dismutase and catalase) levels, lipid peroxidation in terms of malondialdehyde level and total antioxidant status during reproductively active (RAP) and inactive phase (RIP). On the other hand melatonin has been accepted as free radical scavenger acting via receptor (nuclear receptor) or non receptor pathway. To pin point the role of melatonin in regulation of antioxidant enzymes via non receptor mediated pathway in lungs of bird, we checked variation in the nuclear melatonin receptor RORα. Antioxidant enzymes (superoxide dismutase and catalase) exhibited a marked 24h rhythm in lungs being high during night time and coincided almost with the peak of melatonin and total antioxidant status where as malondialdehyde level and nuclear receptor RORα showed inverse relationship with all the above mentioned parameters. These findings suggest that melatonin might be acting as an antioxidant for the free radical load of lung tissue of a tropical bird P. asiatica and its action might be via nuclear receptor RORα. [Copyright &y& Elsevier]

Abstract: Many nuclear hormone receptors (NRs) control lipid, glucose and energy homeostasis in an organ specific manner. Concordantly, dysfunctional NR signalling results in metabolic disease. The Retinoic acid receptor-related orphan receptor alpha (RORα), a member of the NR1F subgroup, is expressed in metabolic tissues. Previous studies identified the role of this NR in dyslipidemia, apo-lipoprotein metabolism and atherosclerosis. Recent data is underscoring the significant role of this orphan NR in the regulation of phase I/II metabolism (bile acids, xenobiotics, steroids etc.), adiposity, insulin signalling, and glucose tolerance. Moreover, oxygenated sterols, have been demonstrated to function as native ligands and inverse agonists. This review focuses on the rapidly emerging and evolving role of RORα in the control of lipid and glucose homeostasis in major mass metabolic tissues. Article from the special issue orphan receptors. [Copyright &y& Elsevier]

Abstract: Luciferase reporter constructs and transient co-transfection approaches demonstrate that elevated expression of RORα1 augments 17-β-estradiol (E2)-induced transcriptional activation of the full-length ERα, but not truncated ERα constructs (ABCD or CDEF), in MCF-7 breast cancer and HEK293 embryonic kidney cells, and that physiologic concentrations of MLT inhibit the individual and combined transcriptional activity of ERα by RORα1 and E2. Gel mobility shift and co-immunoprecipitation (IP)/pull-down assays demonstrate that RORα1 and ERα do not interact directly at the DNA-binding level or as heterodimers, however, RORα1 augments E2-induced pS2 and cyclin D1 mRNA expression while MLT inhibits RORα1/E2-induced expression of pS2 and cyclin D1 in MCF-7 cells. [ABSTRACT FROM AUTHOR]

Abstract: The retinoid-related orphan receptor α (RORα) belongs to the nuclear receptor superfamily and comprises four isoforms generated by different promotor usage and alternative splicing. To better understand its function, the subcellular distribution of RORα was investigated. We could show that subcellular distribution of RORα is cell line and isoform-dependent. Isoform specific differences were mediated by the A/B domains which with the exception of RORα1 contain a signal that mediates cytoplasmic localization. The lack of this signal in RORα1 results in a complete nuclear localization and prevents cell membrane association observed for RORα2, 3, and 4. The region responsible for membrane association was identified as the C-terminal α-helix 12. Furthermore, the hinge region/ligand binding domain mediates nuclear localization. Our results show that isoform specific activity of RORα is not only regulated by different expression and DNA binding affinities but also by different subcellular distribution. Different access to the nucleus reveals an important mechanism regulating the activity of this constitutively active nuclear receptor. [Copyright &y& Elsevier]

Summary: Lipid and carbohydrate homeostasis in higher organisms is governed by an integrated system that has a capacity to rapidly respond to metabolic changes. Numerous signals reciprocally convey information about body fat status from the periphery to central nervous system in the attempt to maintain body weight nearly stable throughout life. The role of adipocyte in energy homeostasis extends its function as a simple energy storage cell. Indeed, adipose tissue not only secretes fatty acids, but is also an active endocrine and paracrine organ due to the production of secreted proteins and lipid indicators collectively called adipokines. These observations have spurred interest in the identification of the transcriptional and other regulatory pathways of adipocyte differentiation. The nuclear receptor, peroxisome proliferator-activated receptor γ (PPARγ) (NR1C3) and members of the CCAAT enhancer-binding protein (C/EBP) family are central mediators controlling adipocyte differentiation and function. Rev-erbα (NR1D1) is an orphan nuclear receptor encoded on the opposite strand of the thyroid receptor α gene. Rev-erbα acts as a negative regulator of transcription binding to the same response element than another orphan nuclear receptor, RORα. Rev-erbα is highly expressed in adipose tissue, skeletal muscle, heart, liver and brain. Rev-erbα expression increases during adipocyte differentiation of 3T3-L1 cells and is induced by PPARγ activation in both 3T3-L1 cells in vitro and in rat adipose tissue in vivo via a direct repeat (DR2) in the Rev-erbα promoter. Ectopic expression of Rev-erbα potentiates the adipocyte differentiation in 3T3-L1 cells. Recent results in vascular smooth muscle cells (VSMCs) indicate that Rev-erbα also controls inflammation by regulating NF-κB responsive genes, such as IL-6 and COX-2. Future studies on a potential role of Rev-erbα on glucose homeostasis and/or inflammation control are thus warranted. [Copyright &y& Elsevier]

Inflammatory bowel disease (IBD) is multi-factorial chronic intestinal inflammation driven by pathogenic T cells, among which a large portion of patients are resistant to current anti-inflammatory regimes. The mechanisms underlying colitis pathogenicity and drug resistance are not fully understood. Here, we demonstrate that RORα is highly expressed in active UC patients, particularly in those non-responsive to anti-TNF treatment. Rorα deficiency in CD4+ T cells greatly reduced colitis development. Mechanistically, RORα regulated T cell infiltration in colon and inhibited T cell apoptosis. Meanwhile, genome-wide occupancy and transcriptome analysis revealed that RORα promoted mTORC1 activation. mTORC1 signaling, also hyperactivated in active UC patients, is necessary for T cell-mediated colitis. Our results thus demonstrate a crucial role of the RORα-mTORC1 axis in CD4+ T cells in promoting IBD, which may be targeted in human patients. [Display omitted] • RORA , but not RORC , is highly expressed in active anti-TNF-resistant UC patients • RORα expression in CD4+ T cells is necessary for colitis development in mice • RORα promotes T cell survival and mTORC1 activation • mTORC1 activation in CD4+ T cells is essential for colitis development in mice In this study, Chi et al. demonstrate that RORα expression is elevated in active, especially anti-TNF therapy-resistant ulcerative colitis patients and that a RORα-mTORC1 axis is crucial for the colitogenic function by CD4+ T cells. [ABSTRACT FROM AUTHOR]

Nonalcoholic fatty liver diseases (NAFLDs) are characterized by excessive triacylglycerol (TAG) accumulation in the liver which contributes to hepatocyte dysfunction, inflammation, and fibrosis. Patatin-like phospholipase domain-containing 3 (PNPLA3; also known as adiponutrin) has emerged as an important enzyme leading to hepatic TAG hydrolysis. Because the I148M substitution in the PNPLA3 gene markedly reduces hepatic TAG hydrolase activity, this genetic variation is strongly associated with increased hepatic TAG in the full spectrum of NAFLDs. The Retinoic acid-related orphan receptor α (RORα) regulates various target genes related to lipid metabolism. Here, we investigated the role of RORα on PNPLA3-mediated hepatic lipid hydrolysis. With blockade of lipid esterification and β-oxidation, RORα enhanced TAG hydrolysis, resulting in increased free glycerol levels. We found a putative RORα response element on the upstream of PNPLA3 gene that was activated by RORα. Furthermore, the inhibitory action of cJUN on the RORα/PNPLA3 axis was enhanced under lipid stress and contributed to hepatic lipid accumulation. In summary, we showed for the first time that RORα activates the transcription of PNPLA3, which suggests that RORα and its ligands represent potential precision therapeutic approaches for NAFLDs. - The nuclear receptor RORα enhances hepatic lipolysis. - RORα is a transcriptional factor to induce PNPLA3 via binding to the promoter region. - The lipid stress-induced cJUN activation inhibits RORα/PNPLA3 axis. - RORα functions to ameliorate hepatic steatosis through PNPLA3-mediated lipolysis. [ABSTRACT FROM AUTHOR]

In hepatocytes, the retinoic acid receptor-related orphan receptor α (RORα) regulates the transcription of diverse genes encoding lipogenic enzymes, antioxidant enzymes, and mitochondrial factors via the regulation of the transcriptional activity of their promoters. The coordination of the expression of RORα by driving its transcription would provide better aspects for managing liver homeostasis. The transcriptional expression of RORα was measured after treatment of RORα agonists on primary hepatocytes and liver. The histone status of Rora gene bodies was examined by analyzing ChIP-seq database. To elucidate molecular mechanism for RORα autoregulation, broad ChIP assays for promoters and enhancers with histone and RORα antibodies were performed. We report that natural and synthetic RORα agonists, cholesterol sulfate and JC1–40, respectively, increased the transcriptional expression of RORα in primary hepatocytes. An analysis of histone status around the Rora gene body identified promoter and enhancer regions of RORα. We found that RORα indirectly increased histone acetylation of H3K9 at the promoter region and directly enhanced histone monomethylation of H3K4 by binding to enhancer regions. Interestingly, disturbance of mixed-lineage leukemia 4 (MLL4), a histone methyltransferase for enhancers, abolished the JC1–40-induced activation of RORα via a decrease in H3K4me1. Finally, we observed that the MLL4-mediated autoregulation of RORα also occurred in human liver cancer cell lines. The ability of RORα to modulate its own transcription is crucial for liver homeostasis, and ligand-dependent autoregulation could amplify the therapeutic effects of RORα in fatty liver diseases. [ABSTRACT FROM AUTHOR]

• Lupus-prone mouse has endothelial dysfunction. • RORα is decreased in aorta of lupus-prone mouse and in SLE medium treated HUVECs. • Melatonin prevents endothelial dysfunction in SLE by activating RORα. Atherosclerotic cardiovascular disease confers significant morbidity and mortality in patients with systemic lupus erythematosus (SLE). A substantial proportion of patients with SLE display accelerated endothelial dysfunction, which precedes cardiovascular disease. Melatonin and its nuclear receptor retinoid-related orphan receptor alpha (RORα) have been reported to have some protective effects on the development of atherosclerosis. However, the function of melatonin in SLE-induced endothelial dysfunction and the role that RORα plays are still unknown. In this study, we found that RORα protein expression was decreased in aortas of lupus-prone mice and in human umbilical vein endothelial cells (HUVECs) cultured with medium containing sera of patients with SLE. Melatonin-treated HUVECs showed a decrease of pro-inflammatory mRNAs [interleukin-1beta (IL-1β), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α)] under the stimulation of SLE medium. Melatonin increased nitric oxide and antioxidant mRNAs (SOD1 , GPX1 , and CAT) and downregulated reactive oxygen species (ROS) level in HUVECs, which may subsequently delay endothelial senescence and promote HUVEC proliferation and repair after injury. Melatonin inhibited SLE medium-induced RAW264.7 macrophage migration. HUVECs pretreated with melatonin expressed less adhesion-related proteins (ICAM-1 and VCAM-1); as a result, these cells adhered to fewer peripheral blood monocytes. In addition, we also showed that the protective effects of melatonin on endothelial cells were largely diminished when RORα was knockdown in HUVECs. In conclusion, by targeting the nuclear receptor RORα, melatonin preserves normal functions of endothelium in SLE by its anti-inflammatory, antioxidant, and anti-senescence effects. RORα may have the potential to become a prophylactic or therapeutic target in preventing endothelial dysfunction and atherosclerotic cardiovascular disease in patients with SLE. [ABSTRACT FROM AUTHOR]

Maresin-1, a pro-resolving lipid mediator, is drawing a great deal of attention in receptor pharmacology, largely because two distinct types of receptor molecules have been reported as the targets of maresin-1. One is retinoic acid-related orphan receptor α (RORα) and the other is leucine-rich repeat domain-containing G protein-coupled receptor 6 (LGR6). RORα is a nuclear receptor and LGR6 is a plasma membrane GPCR. Identification of two different molecular targets raises the following question: What are the pro-resolving functions of each receptor in inflammation resolution, host defense, tissue homeostasis, and wound healing? In this article, I review the new targets from the point of view of pharmacology and maresin-1 resolution along with intracellular signaling molecules. [ABSTRACT FROM AUTHOR]

Melatonin is an endogenous indoleamine hormone involved in various physiological processes. However, the mechanism of melatonin in mediating Leydig cells function has not been fully explained. In this study, we investigated the mechanism through which melatonin inhibits apoptosis in mouse Leydig cells by activating the retinoic acid-related orphan nuclear receptor (ROR) α/p53 signaling pathway. We confirmed the expression and localization of RORα in mouse Leydig cells using immunofluorescence. After treatment with 10 ng/mL melatonin for 36 h, RORα mRNA and protein levels were significantly increased (P < 0.01). TUNEL and flow cytometry showed that melatonin significantly decreased the TUNEL-positive cell ratio and apoptosis rate (P < 0.05). Moreover, melatonin decreased BAX expression and increased BCL-2 expression (P < 0.05). However, the RORα inhibitor SR1001 reversed the inhibitory effects of melatonin on apoptosis (P < 0.05). Additionally, analysis of p53 expression showed that melatonin inhibited p53 mRNA and protein expression (P < 0.05), whereas SR1001 reversed these effects. p53 reversed the anti-apoptotic process involving RORα-mediated melatonin in mouse Leydig cells. Collectively, our findings suggested that melatonin inhibited apoptosis via the RORα/p53 pathway. Unlabelled Image • RORα is expressed in mouse Leydig cells and localized in the nucleus. • Melatonin could inhibit apoptosis of mouse Leydig cells via RORα. • Melatonin inhibits apoptosis in mouse Leydig cells via the retinoic acid-related orphan nuclear receptor α/p53 pathway. [ABSTRACT FROM AUTHOR]

• Estradiol induces RORα expression in osteoblasts. • RORα increases BMP2 expression in MC3T3-E1 cells. • RORα knockdown attenuates estradiol-induced osteoblastic differentiation. The retinoic acid receptor-related orphan receptor alpha (RORα) is a member of the nuclear hormone receptor superfamily. Several studies show that estradiol is related to RORα expression. However, the link between estradiol and RORα in osteoblast differentiation remains unknown. Here, we showed that estradiol induces RORα expression in C3H10T1/2 and MC3T3-E1 cells. RORα overexpression increased the expression of osteogenic genes including bone morphogenetic protein 2 (BMP2), distal-less homeobox 5, inhibitor of DNA binding, runt-related transcription factor 2 (Runx2), and osteocalcin. In addition, RORα increased phosphorylation of smad1/5/9. Furthermore, RORα knockdown suppressed estradiol-induced BMP2 and Runx2 protein level. Also, we confirmed that estradiol-induced ALP staining and matrix mineralization was attenuated in RORα knockdown. Summarily, these results suggest that estradiol-induced RORα promotes osteoblast differentiation. [ABSTRACT FROM AUTHOR]