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The transcription factor NURR1 is essential to the generation and maintenance of midbrain dopaminergic (mDA) neurons and its deregulation is involved in the development of dopamine (DA)-associated brain disorders, such as Parkinson's disease (PD). The old male NURR1 heterozygous knockout (NURR1-KO) mouse has been proposed as a model of PD due to its altered motor performance that was, however, not confirmed in a subsequent study. Based on these controversial results, we explored the effects of the NURR1 deficiency on locomotor activity, motor coordination, brain and plasma DA levels, blood pressure and heart rate of old mice, also focusing on the potential effect of sex. As a probable consequence of the role of NURR1 in DA pathway, we observed that the old NURR1-KO mouse is characterized by motor impairment, and increased brain DA level and heart rate, independently from sex. However, we also observed an alteration in spontaneous locomotor activity that only affects males. In conclusion, NURR1 deficiency triggers sex- and age-specific alterations of behavioral responses, of DA levels and cardiovascular abnormalities. Further studies in simplified systems will be necessary to dissect the mechanism underlying these observations., (© 2022 The Authors. Journal of Neuroscience Research published by Wiley Periodicals LLC.)

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects both lower and upper motor neurons (MNs) in the central nervous system. ALS etiology is highly multifactorial and multifarious, and an effective treatment is still lacking. Neuroinflammation is a hallmark of ALS and could be targeted to develop new therapeutic approaches. Interestingly, the transcription factor Nurr1 has been demonstrated to have an important role in the inflammatory process in several neurological disorders, such as Parkinson's disease and multiple sclerosis. In the present paper, we demonstrate for the first time that Nurr1 expression levels are upregulated in the peripheral blood of ALS patients. Moreover, we investigated Nurr1 function in the SOD1-G93A mouse model of ALS. Nurr1 was strongly upregulated in the spinal cord during the asymptomatic and early symptomatic phases of the disease, where it promoted the expression of brain-derived neurotrophic factor mRNA and the repression of NFκB pro-inflammatory targets, such as inducible nitric oxide synthase. Therefore, we hypothesize that Nurr1 is activated in an early phase of the disease as a protective endogenous anti-inflammatory mechanism, although not sufficient to reverse disease progression. On the basis of these observations, Nurr1 could represent a potential biomarker for ALS and a promising target for future therapies., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2020. Published by The Company of Biologists Ltd.)

The transcription factor NURR1 is a constitutively active orphan receptor belonging to the steroid hormone receptor class NR4A. Although a genetic association between NURR1 and autoimmune inflammatory diseases has never emerged from genome-wide association studies (GWAS), alterations in the expression of NURR1 have been observed in various autoimmune diseases. Specifically, its role in autoimmune inflammatory diseases is mainly related to its capability to counteract inflammation. In fact, NURR1 exerts anti-inflammatory functions inhibiting the transcription of the molecules involved in proinflammatory pathways, not only in the peripheral blood compartment, but also in the cerebral parenchyma acting in microglial cells and astrocytes. In parallel, NURR1 has been also linked to dopamine-associated brain disorders, such as Parkinson's disease (PD) and schizophrenia, since it is involved in the development and in the maintenance of midbrain dopaminergic neurons (mDA). Considering its role in neuro- and systemic inflammatory processes, here we review the evidences supporting its contribution to multiple sclerosis (MS), a chronic inflammatory autoimmune disease affecting the central nervous system (CNS). To date, the specific role of NURR1 in MS is still debated and few authors have studied this topic. Here, we plan to clarify this issue analyzing the reported association between NURR1 and MS in human and murine model studies.

The transcription factor NURR1 regulates the dopamine (DA) signaling pathway and exerts a critical role in the development of midbrain dopaminergic neurons (mDA). NURR1 alterations have been linked to DA-associated brain disorders, such as Parkinson's disease and schizophrenia. However, the association between NURR1 defects and the attention-deficit hyperactivity disorder (ADHD), a DA-associated brain disease characterized by hyperactivity, impulsivity and inattention, has never been demonstrated. To date, a comprehensive murine model of ADHD truly reflecting the whole complex human psychiatric disorder still does not exist. NURR1-knockout (NURR1-KO) mice have been reported to exhibit increased spontaneous locomotor activity, but their complete characterization is still lacking. In the present study a wide-ranging test battery was used to perform a comprehensive analysis of the behavioral phenotype of the male NURR1-KO mice. As a result, their hyperactive phenotype was confirmed, while their impulsive behavior was reported for the first time. On the other hand, no anxiety and alterations in motor coordination, sociability and memory were observed. Also, the number of mDA expressing tyrosine hydroxylase, a rate-limiting enzyme of catecholamines biosynthesis, and DA level in brain were not impaired in NURR1-KO mice. Finally, hyperactivity has been shown to be recovered by treatment with methylphenidate, the first line psychostimulant drug used for ADHD. Overall, our study suggests that the NURR1 deficient male mouse may be a satisfactory model to study some ADHD behavioral phenotypes and to test the clinical efficacy of potential therapeutic agents.

Parkinson's disease (PD) is a neurodegenerative pathology characterized by the degeneration of midbrain dopamine neurons, whose development and maintenance in brain is related to the transcription factor NR4A2 (also called Nurr1). Notably, NR4A2 is a neuroprotective agent with anti-inflammatory role in microglia and astrocytes. Furthermore, mutations in NR4A2 gene are associated to the familial form of PD, and its gene expression level is down-regulated in blood obtained from PD patients. NR4A2 belongs to the NR4A subfamily consisting of three members: NR4A1, NR4A2, and NR4A3. The NR4A subfamily shares high degree of homology in their molecular structure and cooperates in a spectrum of functions ranging from central nervous system to immune control during physiological and pathological conditions. Considering the close functional link between the member of NR4A subfamily, we performed a gene expression analysis of NR4A1, NR4A2, and NR4A3 in peripheral blood obtained from PD patients and healthy controls (HC). Then, in order to evaluate possible involvement of the NR4A subfamily in other neurodegenerative processes, we carried out the same analysis on blood obtained from Alzheimer's disease (AD) patients. A correlation between clinical features and gene expression was also evaluated. We found a marked down-regulated gene expression of the NR4A subfamily obtained from PD patients, but only a NR4A1 decrease in AD patients compared to HC. This study reports that the entire NR4A subfamily and not only NR4A2 could be systemically involved in PD suggesting that the study of these factors could be a promising approach to develop PD therapy.

Objective: Nurr1 plays anti-inflammatory functions in astrocytes/microglia. Gene expression analysis reveals Nurr1 down-regulation in PBMCs of MS patients that negatively correlates with disease aggressiveness. This study assesses the consequences of Nurr1 reduction in a MS model represented by EAE., Methods: EAE was induced in heterozygous Nurr1 knockout mice. Clinical course was evaluated during pre-symptomatic, acute, and chronic phases. Neurohistopathological state was analyzed in spinal cord., Results and Conclusions: Nurr1 defect induces early EAE onset and increases inflammatory infiltrates in spinal cord suggesting a Nurr1 role in the early phase of EAE.

Multiple sclerosis (MS) is an autoimmune chronic disease of the central nervous system (CNS) characterized by immune-mediated inflammation, demyelination and subsequent axonal damage. Gene expression profiling showed that Nurr1, an orphan nuclear receptor, is down-regulated in peripheral blood mononuclear cells of MS patients. Nurr1 exerts an anti-inflammatory role repressing the activity of the pro-inflammatory transcription factor NF-kB. Here, we report that the preventive treatment with isoxazolo-pyridinone 7e, an activator of Nurr1 signaling pathway, reduces the incidence and the severity of a MS murine model, i.e. experimental autoimmune encephalomyelitis (EAE). The compound is able to attenuate inflammation and neurodegeneration in spinal cords of EAE mice by an NF-kB pathway-dependent process.

We recently found a gene signature for multiple sclerosis (MS) that reverted to normal during pregnancy in MS patients and included NR4A2 and TNFAIP3, key molecules in anti-inflammatory processes. Here we focus on the expression levels of these two genes in monocytes and CD4+ T cells from healthy controls and treatment-naïve RRMS patients. Our findings show that monocytes play a key role in the dysregulated anti-inflammatory response, being the expression of both genes down-regulated in these cells in RRMS patients with respect to healthy individuals. CD4+ T cells seem to have only a marginal part, because we can observe only a slight down-regulation in NR4A2., (Copyright © 2014 Elsevier B.V. All rights reserved.)