AP-2beta represses D(1A) dopamine receptor gene transcription in neuro2a cells

The regulatory role of AP-2β in monoaminergic neurotransmitter systems: insights on its signalling pathway, linked disorders and theragnostic potential

Monoaminergic neurotransmitter systems play a central role in neuronal function and behaviour. Dysregulation of these systems gives rise to neuropsychiatric and neurodegenerative disorders with high prevalence and societal burden, collectively termed monoamine neurotransmitter disorders (MNDs). Despite extensive research, the transcriptional regulation of monoaminergic neurotransmitter systems is not fully explored. Interestingly, certain drugs that act on these systems have been shown to modulate central levels of the transcription factor AP-2 beta (AP-2β, gene: TFAP2Β). AP-2β regulates multiple key genes within these systems and thereby its levels correlate with monoamine neurotransmitters measures; yet, its signalling pathways are not well understood. Moreover, although dysregulation of TFAP2Β has been associated with MNDs, the underlying mechanisms for these associations remain elusive. In this context, this review addresses AP-2β, considering its basic structural aspects, regulation and signalling pathways in the controlling of monoaminergic neurotransmitter systems, and possible mechanisms underpinning associated MNDS. It also underscores the significance of AP-2β as a potential diagnostic biomarker and its potential and limitations as a therapeutic target for specific MNDs as well as possible pharmaceutical interventions for targeting it. In essence, this review emphasizes the role of AP-2β as a key regulator of the monoaminergic neurotransmitter systems and its importance for understanding the pathogenesis and improving the management of MNDs.

Search for factors contributing to resistance to the electroconvulsive seizure treatment model using adrenocorticotrophic hormone-treated mice

Approximately one third of patients with depression remain treatment resistant with existing antidepressants, suggesting that the currently-available antidepressants cannot induce appropriate responses in the brains of all patients. Long-term exposure to adrenocorticotrophic hormone (ACTH) has been proposed as a model that mimics at least some aspects of clinical treatment-resistant depression in rodents. The purpose of this study was to explore potential causes of antidepressant treatment resistance using the chronic ACTH-treated mouse model. We subjected ACTH-treated mice to a rodent model of electroconvulsive therapy, i.e., electroconvulsive seizure (ECS), which induces various molecular and cellular changes, including in gene expression and adult neurogenesis in the hippocampus. First, behavioral effect of repeated ECS in the forced swim test (FST) was examined. In our experimental setting, ACTH-treated mice showed resistance to the antidepressant-like effect of ECS in the FST. We then examined which cellular and molecular changes induced by ECS were attenuated by ACTH administration. Chronic ACTH treatment suppressed the increase of gene expression such as of Bdnf, Npy, and Drd1 induced by ECS in the hippocampus. In contrast, there was no difference in ECS-induced promotion of the early neurogenetic process in the hippocampus between ACTH-treated and control mice. Our results suggest the possibility that impaired neuromodulation and monoamine signaling in the hippocampus are among the factors contributing to antidepressant treatment resistance.

Analysis of the Promoter Region of Human Dopamine Receptor D1

Dysregulation of dopamine receptor D1 (DRD1) is involved in multiple neuropsychiatric disorders. The 5' regulatory region of DRD1 has not been characterized fully. We applied the luciferase assay and the electrophoretic mobility shift assay to explore the activity of the 5' regulatory region of DRD1 in SH-SY5Y and 293T cells. We found that the promoter region of DRD1 corresponded to positions - 1250 to + 250 in the DNA sequence, and the putative core promoter region was from - 113 to + 250 (transcriptional start site of exon, +1). The sequence 5'-gggacgcgcgggcggggtgggctgtgccccgcgggaaccccgccggcctgtgcgcttgctg-3' was identified as a possible transcription factor-binding domain. Further research is warranted to explore the function of the 5' regulatory region of DRD1.

Methamphetamine induces Shati/Nat8L expression in the mouse nucleus accumbens via CREB- and dopamine D1 receptor-dependent mechanism

Shati/Nat8L significantly increased in the nucleus accumbens (NAc) of mice after repeated methamphetamine (METH) treatment. We reported that Shati/Nat8L overexpression in mouse NAc attenuated METH-induced hyperlocomotion, locomotor sensitization, and conditioned place preference. We recently found that Shati/Nat8L overexpression in NAc regulates the dopaminergic neuronal system via the activation of group II mGluRs by elevated N-acetylaspartylglutamate following N-acetylaspartate increase due to the overexpression. These findings suggest that Shati/Nat8L suppresses METH-induced responses. However, the mechanism by which METH increases the Shati/Nat8L mRNA expression in NAc is unclear. To investigate the regulatory mechanism of Shati/Nat8L mRNA expression, we performed a mouse Shati/Nat8L luciferase assay using PC12 cells. Next, we investigated the response of METH to Shati/Nat8L expression and CREB activity using mouse brain slices of NAc, METH administration to mice, and western blotting for CREB activity of specific dopamine receptor signals in vivo and ex vivo. We found that METH activates CREB binding to the Shati/Nat8L promoter to induce the Shati/Nat8L mRNA expression. Furthermore, the dopamine D1 receptor antagonist SCH23390, but not the dopamine D2 receptor antagonist sulpiride, inhibited the upregulation of Shati/Nat8L and CREB activities in the mouse NAc slices. Thus, the administration of the dopamine D1 receptor agonist SKF38393 increased the Shati/Nat8L mRNA expression in mouse NAc. These results showed that the Shati/Nat8L mRNA was increased by METH-induced CREB pathway via dopamine D1 receptor signaling in mouse NAc. These findings may contribute to development of a clinical tool for METH addiction.

Microsatellite polymorphisms associated with human behavioural and psychological phenotypes including a gene-environment interaction

Background

The genetic and environmental influences on human personality and behaviour are a complex matter of ongoing debate. Accumulating evidence indicates that short tandem repeats (STRs) in regulatory regions are good candidates to explain heritability not accessed by genome-wide association studies.

Methods

We tested for associations between the genotypes of four selected repeats and 18 traits relating to personality, behaviour, cognitive ability and mental health in a well-studied longitudinal birth cohort (n = 458-589) using one way analysis of variance. The repeats were a highly conserved poly-AC microsatellite in the upstream promoter region of the T-box brain 1 (TBR1) gene and three previously studied STRs in the activating enhancer-binding protein 2-beta (AP2-β) and androgen receptor (AR) genes. Where significance was found we used multiple regression to assess the influence of confounding factors.

Results

Carriers of the shorter, most common, allele of the AR gene’s GGN microsatellite polymorphism had fewer anxiety-related symptoms, which was consistent with previous studies, but in our study this was not significant following Bonferroni correction. No associations with two repeats in the AP2-β gene withstood this correction. A novel finding was that carriers of the minor allele of the TBR1 AC microsatellite were at higher risk of conduct problems in childhood at age 7-9 (p = 0.0007, which did pass Bonferroni correction). Including maternal smoking during pregnancy (MSDP) in models controlling for potentially confounding influences showed that an interaction between TBR1 genotype and MSDP was a significant predictor of conduct problems in childhood and adolescence (p < 0.001), and of self-reported criminal behaviour up to age 25 years (p ≤ 0.02). This interaction remained significant after controlling for possible confounders including maternal age at birth, socio-economic status and education, and offspring birth weight.

Conclusions

The potential functional importance of the TBR1 gene’s promoter microsatellite deserves further investigation. Our results suggest that it participates in a gene-environment interaction with MDSP and antisocial behaviour. However, previous evidence that mothers who smoke during pregnancy carry genes for antisocial behaviour suggests that epistasis may influence the interaction.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-017-0374-y) contains supplementary material, which is available to authorized users.

Dopamine D1 receptor (DRD1) 5' region haplotypes significantly affect transcriptional activity in vitro

The role of dopamine D1 receptor (DRD1) gene promoter polymorphisms in schizophrenia remains controversial. We aimed to characterize the polymorphisms in the promoter region because little is known about the extent of variance in this region and potential roles in gene transcription activity. In a previous case-control study, we amplified and genotyped the polymorphisms of DRD1 gene. According to its haplotype estimation, we identified eight SNPs and confirmed ten different haplotypes by cloning and sequencing the fragment spanning -1990 to +10. The promoter activity of these haplotypes was analyzed using dual luciferase assays in SH-SY5Y and HEK293 cells. Compared with the reference haplotype, the constructed haplotypes containing different variation sites could significantly alter the luciferase activity. Additionally, the prediction of the transcription factor binding sites was performed. Our examination could provide the informative reference for the role of DRD1 gene promoter in schizophrenia.

Transcription factor AP2 beta involved in severe female alcoholism

Susceptibility to alcoholism and antisocial behavior exhibits an evident link to monoaminergic neurotransmission. The serotonin system in particular, which is associated with regulation of mood and behavior, has an influence on personality characters that are firmly connected to risk of developing alcoholism and antisocial behavior, such as impulsiveness, and aggression. The transcription factor TFAP2b has repeatedly been shown to be involved in monoaminergic transmission, likely due to a regulatory effect on genes that are fundamental to this system, e.g. monoamine oxidase type A, and the serotonin transporter. Recent research has identified a functional polymorphism in the gene encoding TFAP2B that regulates its level of expression. In the present study we have compared a sample of female alcoholics (n=107), sentenced to institutional care for their severe addiction, contrasted against a control sample of adolescent females (n=875). The results showed that parental alcohol misuse was significantly more common among the alcoholic females, and also that parental alcohol misuse was associated with a reduction in age of alcohol debut. We also addressed the question of whether a functional TFAP2b polymorphism was associated with alcoholism. Results showed that the high-functioning allele was significantly more common among the female alcoholics, compared to the non-alcoholic controls. Furthermore, the results also indicated that psychosocial factors, in terms of parental alcohol misuse, depression or psychiatric disorder, had an influence on the association. It was observed that the genetic association was restricted to the subset of cases that had not experienced these negative psychosocial factors.

Electrophysiological and behavioral correlates of polymorphisms in the transcription factor AP-2beta coding gene

Transcription factor AP-2beta may influence brain monoaminergic systems by regulating target genes. Several monoaminergic genes, including the serotonin transporter gene, have AP-2beta binding sites. Late auditory-evoked potentials (P1, N1/P2) and impulsiveness-related personality traits are correlated, and both are modulated by monoaminergic neurotransmission. The present study assesses the impact of two AP-2beta polymorphisms (VNTRs within intron 1 and 2) together with the serotonin transporter polymorphism 5-HTTLPR on late auditory-evoked potentials and personality for the first time. EEG was recorded from 91 male subjects at central electrode positions while tones of six intensity levels were presented. Additionally, subjects completed personality questionnaires. Both AP-2beta polymorphisms revealed significant main effects on P1, and haplotype analysis confirmed the contribution of both AP-2beta-polymorphisms. Additionally, AP-2beta and 5-HTTLPR showed interactions with respect to P1. 5-HTTLPR revealed a main effect on N1/P2 but not P1. Impulsiveness showed an association with intron 1 VNTR. The results are discussed with respect to differential impact of AP-2beta polymorphisms and 5-HTTLPR on the monoaminergic systems. The findings promote replication in a larger sample and suggest a potential usefulness of AP-2beta polymorphisms in explaining or predicting central nervous diseases, drug effects and side effects.

Association analysis of 15 polymorphisms within 10 candidate genes for antisocial behavioural traits

This study sought to test 15 simple sequence repeat polymorphisms within 10 candidate genes for association with antisocial behavioural traits. Genes included were those known to regulate dopamine synthesis and transmission in the brain (DBH, DRD2, MAOA, TFAP2B, NR4A2, LMX1B) and those involved in the differentiation of social and sexual behaviour in men and women (AR, ESR1, OXTR, AVPR1A). Participants were Caucasians (men=1007, women=1089) aged 20-24 years who were assessed for indicators of antisocial traits such as pseudo-maturity, substance misuse and unstable lifestyle. Significant associations for antisocial traits were found with AR and ESR1 polymorphisms in men, and with polymorphisms within NR4A2 and TFAP2B in women. The association with TFAP2B remained significant after correction for multiple testing. This pattern of associations suggests that genetic variation within transcription factors may in part explain the variation observed in the population for antisocial behavioural phenotypes.

Brain-derived neurotrophic factor regulates the expression of D1 dopamine receptors

We have previously demonstrated that the CAD catecholaminergic neuronal cell line is an appropriate model system to study the regulation of D(1) dopamine receptor expression. In this report, we show that brain-derived neurotrophic factor (BDNF) up-regulates the expression of D(1) dopamine receptor in CAD cells. In addition, by comparing D(1) receptor mRNA expression in wild-type, heterozygous and homozygous trkB knockout mice, we show that TrkB receptor signaling up-regulates D(1) receptor expression in vivo. In CAD cells expressing the TrkB receptor, BDNF increased D(1) receptor mRNA in a time- and dose-dependent manner with a fourfold increase in D(1) receptor mRNA observed as early as 3 h with 10 ng/mL of BDNF. Using different classes and concentrations of kinase inhibitors, we determined that BDNF-induced increase of D(1) receptor mRNA is mediated by the phosphatidylinositol 3-kinase signaling pathway. The increase required both new transcription and protein synthesis, as it was blocked by actinomycin D and cyclohexamide, respectively. Promoter deletion analysis identified a D(1) promoter region necessary for mediating the effect of BDNF. These results provide novel evidence that D(1) dopamine receptor expression is regulated by BDNF and its signaling pathway.

Changes in cytoskeletal gene expression linked to MPTP-treatment in Mice

Parkinson's disease is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra and a marked reduction of dopamine (DA) levels in the striatum. Binding to its specific receptors, DA switches on a complex program of intracellular signaling that regulates gene expression. We evaluated the changes in striatal gene expression in a mouse model of Parkinson's disease, using differential display analysis. The mRNA for the cytoskeleton family proteins, radixin, cofilin and centractin/ARP-1, was abnormally expressed in the striatum of these MPTP-treated mice. Moreover, we also found that radixin mRNA and its protein levels are under DA control through specific D1-dopaminergic receptors in a dose- and time-dependent manner in the GT1-7 neural cell line. These findings suggest a role for DA for regulation of cytoskeletal proteins involved in the integrity and function of synapsis.

Transcription factor AP-2 and monoaminergic functions in the central nervous system

In the central nervous system, transcription factor AP-2 family is one of the critical regulatory factors for neural gene expression and neuronal development. Several genes in the monoaminergic systems display AP-2 binding sites in regulatory regions. In addition, brainstem levels of transcription factor AP-2alpha and AP-2beta are positively correlated to monoamine measures in rat forebrain, suggesting a regulatory role of AP-2 also in the adult brain. Great changes in psychiatric phenotypes due to genetic factors are seldom the result of a single gene polymorphism. Recently, identification of combinations of candidate genes that are all linked to one disease or psychiatric phenotype has been discussed. The expression of these candidate genes might be regulated by the same transcription factors, e.g. AP-2. Recent data on transcription factor AP-2 family in relation to monoaminergic functions are described in this paper. Transcription factor AP-2beta genotype has been studied in relation to personality, platelet monoamine oxidase (MAO) activity, CSF-levels of monoamine metabolites, binge-eating disorder, premenstrual dysphoric disorder, and schizophrenia. Furthermore, the involvement of AP-2 in the molecular mechanism of antidepressant drugs is discussed. Altogether, this paper discusses data supporting a notion that the transcription factor AP-2 family is involved in the regulation of the monoaminergic systems both pre- and postnatally, and, therefore, might be involved in the pathophysiology of neuropsychiatric disorders.

In vivo antitumor efficacy of STAT3 blockade using a transcription factor decoy approach: implications for cancer therapy

The development of more effective prevention and treatment strategies for solid tumors is limited by an incomplete understanding of the critical growth pathways that are activated in carcinogenesis. Signal transducers and activators of transcription (STAT) proteins have been linked to transformation and tumor progression. Several approaches have been used to block STAT3 in cancer cells resulting in reduced proliferation and apoptosis. We tested the hypothesis that blocking STAT3 activation using a transcription factor decoy approach would decrease tumor growth and STAT3 target gene expression in vivo. In a xenograft model of squamous cell carcinoma of the head and neck (SCCHN), daily administration of the STAT3 decoy (25 microg) resulted in decreased tumor volumes, abrogation of STAT3 activation, and decreased expression of STAT3 target genes (VEGF, Bcl-xL, and cyclin D1) compared to treatment with a mutant control decoy. Blockade of STAT3 with the STAT3 decoy also induced apoptosis and decreased proliferation, an effect that was augmented when the STAT3 decoy was combined with cisplatin, both in vitro and in vivo. These results suggest that a transcription factor decoy approach may be used to target STAT3 in cancers that demonstrate increased STAT3 activation including SCCHN.

The role of Sp1 and AP-2 in basal and protein kinase A--induced expression of mitochondrial serine:pyruvate aminotransferase in hepatocytes

Transcription of mitochondrial serine:pyruvate aminotransferase (SPT) mRNA (SPTm-mRNA) in rat liver is unique in that it occurs from the upstream site of the two transcription start sites within the first exon of the SPT gene and is selectively enhanced by cAMP via the protein kinase A (PKA) signaling pathway. In this study, we identified the DNA elements and nuclear factors responsible for the basal and PKA-induced activities of the upstream promoter. By using a luciferase reporter assay with HepG2 cells, DNase I footprinting analysis, and gel shift experiments, we identified the binding sites for Sp1 and AP-2 within the regions -125 to -89 and -14 to +10, respectively. Mutational analyses indicated that these regions are essential for the transcription factor binding and the SPT promoter activity. Expression of AP-2 caused a marked increase in the basal promoter activity to about the same level as that achieved by PKA. On the other hand, both the basal and PKA-induced activities were elevated by overexpression of Sp1, its effect on PKA-induced activity being more pronounced with coexpression of CBP and repressed by E1A oncoprotein. These results suggest that AP-2 and Sp1 regulate basal promoter activity, and Sp1 is also involved in PKA-mediated expression of the rat SPT gene in concert with the transcriptional coactivator CBP.