NR4A2 and schizophrenia: lack of association in a Portuguese/Brazilian study

Working memory deficits in schizophrenia are associated with the rs34884856 variant and expression levels of the NR4A2 gene in a sample Mexican population: a case control study

BACKGROUND

Cognitive functions represent useful endophenotypes to identify the association between genetic variants and schizophrenia. In this sense, the NR4A2 gene has been implicated in schizophrenia and cognition in different animal models and clinical trials. We hypothesized that the NR4A2 gene is associated with working memory performance in schizophrenia. This study aimed to analyze two variants and the expression levels of the NR4A2 gene with susceptibility to schizophrenia, as well as to evaluate whether possession of NR4A2 variants influence the possible correlation between gene expression and working memory performance in schizophrenia.

METHODS

The current study included 187 schizophrenia patients and 227 controls genotyped for two of the most studied NR4A2 genetic variants in neurological and neuropsychiatric diseases. Genotyping was performed using High Resolution Melt and sequencing techniques. In addition, mRNA expression of NR4A2 was performed in peripheral mononuclear cells of 112 patients and 118 controls. A group of these participants, 54 patients and 87 controls, performed the working memory index of the WAIS III test.

RESULTS

Both genotypic frequencies of the two variants and expression levels of the NR4A2 gene showed no significant difference when in patients versus controls. However, patients homozygous for the rs34884856 promoter variant showed a positive correlation between expression levels and auditory working memory.

CONCLUSIONS

Our finding suggested that changes in expression levels of the NR4A2 gene could be associated with working memory in schizophrenia depending on patients' genotype in a sample from a Mexican population.

Association Between NR4A2 Gene Polymorphism and Depressive Symptoms and Antidepressant Effect

OBJECTIVE

Although the pathogenesis of major depressive disorder (MDD) is still unclear, studies have shown that the dopaminergic system of depressed patients is defective, and that NR4A2 is an important transcription factor affecting the development and maintenance of dopaminergic neurons. As such, NR4A2 levels affected by NR4A2 single nucleotide polymorphisms (SNPs) may be associated with MDD. This study examined whether NR4A2 SNPs are associated with depressive symptoms and antidepressant efficacy.

METHODS

A total of 441 patients with first-episode depression were enrolled in this study. We analysed three SNPs of NR4A2, using the 17-item Hamilton Depression Rating Scale (HAM-D) and its four factors to obtain scores at baseline and at the end of 6 weeks. UNPHASED software was employed for quantitative character analysis, and SPSS software was adopted for antidepressant efficacy analysis.

RESULTS

Patients with rs12803-A exhibited higher scores of retardation symptoms. Patients with the rs834834-C allele and rs834834-CC genotype had higher retardation symptom scores. Patients with rs3769340 exhibited greater antidepressant efficacy.

CONCLUSION

NR4A2 gene polymorphisms are associated with retardation symptoms, somatic symptoms (gastro-intestinal), anxiety-based somatic symptoms, insight, and weight loss in patients with MDD. Additionally, rs3769340 may be a predictor of antidepressant efficacy in patients with major depressive disorder.

Baduanjin exerts anti-diabetic and anti-depression effects by regulating the expression of mRNA, lncRNA, and circRNA

BACKGROUND

Baduanjin, a traditional Chinese exercise therapy, has been widely used in China to treat type 2 diabetes (T2DM) with depression (DD). However, the underlying mechanism of Baduanjin in anti-DD is unclear. This study was focused on investigating the effects of Baduanjin on symptoms of depression and blood glucose in patients with DD and the underlying mechanism.

METHODS

We performed a 12-week Baduanjin intervention on patients with DD and longitudinally compared the differential expressions of lncRNAs, circRNAs, and mRNAs between pre- (BDD) and post- (ADD) Baduanjin intervention in the same group. Subsequently, Gene Ontology (GO) and pathway analysis was performed to investigate the function of differentially expressed mRNAs. Finally, Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was used to verify the sequencing result and the mRNA-lncRNA regulatory network was constructed.

RESULTS

The blood glucose level, depression index scores, and PHQ9 scores of the patients with DD were significantly decreased (P < 0.05) after Baduanjin intervention. Compared to BDD, 207 lncRNAs, 266 circRNAs, and 610 differentially expressed mRNAs were identified in ADD. Kyoto Encyclopedia of Genes and Genomes (KEGG) and GO showed that the significantly dysregulated mRNAs were mainly involved in immune function and inflammatory response pathways, and various signaling pathways including IL-17 and TNF. In addition, we selected five differentially expressed lncRNAs to construct an lncRNA-mRNA regulatory network, and found a total of 1045 mRNAs associated with them.

CONCLUSIONS

Our research is the first systematic profiling of mRNA, lncRNA, and circRNA in patients of ADD and BDD, and provides valuable insights in the potential mechanism of Baduanjin in anti-DD. Further, it was confirmed that Baduanjin is a safe and effective intervention for patients with DD because it can effectively ameliorate the symptoms of depression and blood glucose levels in patients with DD by regulating the dysregulated expression of lncRNA, mRNA, and circRNA.

Association between NR4A2 genetic variation and schizophrenia: A comprehensive systematic review and meta-analysis

The homo sapiens nuclear receptor subfamily 4, group A (NR4A2) genetic variation has been implicated as a risk factor for schizophrenia (SZ). Nevertheless, the results are inconclusive. We conducted a comprehensive systematic review and meta-analysis to quantify the impact of NR4A2 variation on the risk of SZ. All eligible case-control studies published up to September 2014 were identified by searching PubMed OVID, EBSCO, PsycINFO and ISI web of knowledge. Pooled odds ratio with 95% confidence interval were used to access the strength of association in fixed- or random-effects model. Seven studies that reported 17 variants with a total of 3027 participants were included. Of these variants, five ones (rs143618355, rs199674295, c.366-369 del TAC, c.-469delG and P4) were present only in cases, and three ones (rs35479735, rs3832066 and rs397706674) were available for meta-analysis. Overall, there was no significant association between the three variants and SZ risk under allele model, dominant model and recessive model. The results failed to reveal significant link between NR4A2 polymorphism and SZ risk. However, large-sized and well-designed studies are warranted to validate our findings.

Altered gene expression in the dorsolateral prefrontal cortex of individuals with schizophrenia

The underlying pathology of schizophrenia (SZ) is likely as heterogeneous as its symptomatology. A variety of cortical and subcortical regions, including the prefrontal cortex, have been implicated in its pathology, and a number of genes have been identified as risk factors for disease development. We used in situ hybridization (ISH) to examine the expression of 58 genes in the dorsolateral prefrontal cortex (DLPFC, comprised of Brodmann areas 9 and 46) from 19 individuals with a premorbid diagnosis of SZ and 33 control individuals. Genes were selected based on: (1) previous identification as risk factors for SZ; (2) cell type markers or (3) laminar markers. Cell density and staining intensity were compared in the DLPFC, as well as separately in Brodmann areas 9 and 46. The expression patterns of a variety of genes, many of which are associated with the GABAergic system, were altered in SZ when compared with controls. Additional genes, including C8orf79 and NR4A2, showed alterations in cell density or staining intensity between the groups, highlighting the need for additional studies. Alterations were, with only a few exceptions, limited to Brodmann area 9, suggesting regional specificity of pathology in the DLPFC. Our results agree with previous studies on the GABAergic involvement in SZ, and suggest that areas 9 and 46 may be differentially affected in the disease. This study also highlights additional genes that may be altered in SZ, and indicates that these potentially interesting genes can be identified by ISH and high-throughput image analysis techniques.

NR4A2: effects of an "orphan" receptor on sustained attention in a schizophrenic population

NR4A2 (nuclear receptor subfamily 4 group A member 2) or Nurr1 is a transcription factor implied in the differentiation, maturation, and survival of dopaminergic neurons. It also has a role in the expression of several proteins that are necessary for the synthesis and regulation of dopamine (DA), such as tyrosine hidroxilase, dopamine transporter, vesicular monoamine transporter 2, and cRET. DA is an important neurotransmitter in attentional pathways. Our aim was to evaluate the influence of NR4A2 gene in the performance of schizophrenia (SZ) patients and healthy subjects on a sustained attention task. For this study, we collected 188 SZ subjects (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) and 100 control individuals. We genotyped 5 tag SNPs in NR4A2 gene: rs1150143 (C/G), rs1150144 (A/G), rs834830 (A/G), rs1466408 (T/A), and rs707132 (A/G). We also analyzed the influence of its haplotypes (frequency>5%). To examine sustained attention, all the individuals completed the Degraded Stimulus Continuous Performance Test. We evaluated "hits," "reaction time," "sensibility a," and "false alarms." In the schizophrenic group, recessive genotypes of rs1150143, rs1150144, rs834830, and rs707132 were associated with a worse performance. SZ subjects who carried GGGTG haplotype showed less hits (P<.004), lower sensibility a scores (P<.009), and a higher reaction time (P=.013). We observed a sex effect of the gene: genotype and haplotype associations were only present in the male group. We conclude that NR4A2 gene is involved in attentional deficits of SZ patients, modifying hits, sensibility a, and reaction time.

Nur-related receptor 1 gene polymorphisms and alcohol dependence in Mexican Americans

AIM: To investigate the association of polymorphisms of nur-related receptor 1 (Nurr1) and development of alcohol dependence in Mexican Americans.

METHODS: Peripheral blood samples were collected from 374 alcoholic and 346 nonalcoholic Mexican Americans; these two groups were sex- and age-matched. Sample DNA was extracted and genomic DNA was amplified by polymerase chain reaction. The -2922(C) 2-3 polymerase chain reaction products were digested with Sau96I, alleles of 1345(G/C), and -1198(C/G) in the regulatory region as well as Ex+132 (G/T/A/C) and Ex+715(T/-) in exon 3 were studied by sequencing.

RESULTS: The C2/C2, C2/C3, C3/C3 genotype distribution of -2922(C) 2-3 was 34.4%, 38.2% and 27.5% in the nonalcoholic group compared to 23.3%, 51.2% and 25.4% in the alcoholic group (P = 0.001). The C/C, C/G, G/G genotype distribution of -1198(C/G) was 23.5%, 46.1% and 30.3% in the nonalcoholic group compared to 13.9%, 50.9% and 35.3% in the alcoholic group (P = 0.007). However, the -1345 (G/C), Ex3+132(G/T/A/C) and Ex3+715(T/-) alleles were not polymorphic in Mexican Americans, and all those studied had G/G, G/G and T/T genotype for these three alleles, respectively. The -2922(C) 2-3 did not show allele level difference between alcoholic and nonalcoholic individuals, but -1198 (C/G) showed a significant allele frequency difference between alcoholic (39.3%) and nonalcoholic (46.6%) populations (P = 0.005). Excluding obese individuals, significant differences were found at both genotypic and allelic levels for the -2922(C) 2-3 polymorphism (P = 0.000 and P = 0.049) and the -1198 (C/G) polymorphism (P = 0.008 and P = 0.032) between nonobese alcoholics and nonobese controls. Excluding smokers, a significant difference was found only at the genotypic level for the -2922(C) 2-3 polymorphism (P = 0.037) between nonsmoking alcoholics and nonsmoking controls, but only at the allelic level for the -1198(C/G) polymorphism (P = 0.034).

CONCLUSION: Polymorphisms in the regulatory region of Nurr1 are implicated in pathogenesis of alcohol dependence and the Nurr1/dopamine signaling pathway might be important for this dependence development in Mexican Americans.

Knockdown of Nurr1 in the rat hippocampus: implications to spatial discrimination learning and memory

Nurr1 expression is up-regulated in the brain following associative learning experiences, but its relevance to cognitive processes remains unclear. In these studies, rats initially received bilateral hippocampal infusions of control or antisense oligodeoxynucleotides (ODNs) 1 h prior to training in a holeboard spatial discrimination task. Such pre-training infusions of nurr1 antisense ODNs caused a moderate effect in learning the task and also impaired LTM tested 7 d later. In a second experiment, ODN infusions were given immediately after the animals had received two sessions of training, during which all animals showed normal learning. Although antisense treated rats were significantly impaired during the post-infusion stages of acquisition of the task, no group differences were observed during the LTM test given 7 d later. These animals were subjected 3 d later to reversal training in the same maze in the absence of any additional treatments. Remarkably, rats previously treated with antisense ODNs displayed perseveration: The animals were fixated with the previously learned pattern of baited holes, causing them to be significantly impaired in the extinction of acquired spatial preferences and future learning. We postulate that Nurr1 function in the hippocampus is important for normal cognitive processes.

Thyroid hormones and retinoids: a possible link between genes and environment in schizophrenia

Phenotypic discordance for schizophrenia in monozygotic twins clearly indicates involvement of environmental factors as key determinants in disease development. Positive findings from genome scans, linkage and association studies apply in only a minority of those affected, while post-mortem brain investigations reveal altered expression of genes and proteins involved in numerous neurodevelopmental, metabolic and neurotransmitter pathways. Such altered expressions could result, on the one hand, from mutations in coding regions or polymorphisms in the promoter and regulatory regions in genes within those areas identified by gene searches or, on the other hand, from inadequate amounts of modulators, transporters and synthesizers of transcription factors necessary for regulation of the putative genes. Hormones and vitamins are such modulators. They could serve as bridges between genes and environment in schizophrenia. Multiple evidence supports the suggestion of retinoids and thyroid hormones as plausible actors in these roles. Both are not only essential for normal development of the central nervous system but also regulate the expression of many neurotransmitters, their synthesizing enzymes and receptors, and other genes in broader signaling transduction cascades affecting pathways that are altered in response to treatment. Functional and positional candidate genes include retinoic acid and thyroid hormone receptors, retinaldehyde dehydrogenases and deiodinases, which synthesize the powerful morphogens, retinoic acid and triiodothyronine, and the enzymes involved in their inactivation. This review highlights selective evidence supporting the retinoid and thyroid hormone hypotheses of schizophrenia.