Genes Involved in Neurodevelopment, Neuroplasticity, and Bipolar Disorder: CACNA1C, CHRNA1, and MAPK1

Synaptotagmin-4 induces anhedonic responses to chronic stress via BDNF signaling in the medial prefrontal cortex

Stressful circumstances are significant contributors to mental illnesses such as major depressive disorder. Anhedonia, defined as loss of the ability to enjoy pleasure in pleasurable situations, including rewarding activities or social contexts, is considered a key symptom of depression. Although stress-induced depression is associated with anhedonia in humans and animals, the underlying molecular mechanisms of anhedonic responses remain poorly understood. In this study, we demonstrated that synaptotagmin-4 (SYT4), which is involved in the release of neurotransmitters and neurotrophic factors, is implicated in chronic stress-induced anhedonia. Employing chronic unpredictable stress (CUS), we evaluated two subpopulations of mice, susceptible (SUS, anhedonic) and resilient (RES, nonanhedonic), based on sucrose preference, which was strongly correlated with social reward. The FosTRAP (targeted recombination in active populations) system and optogenetic approach revealed that neural activity in the medial prefrontal cortex (mPFC) was significantly associated with CUS-induced anhedonic behavioral phenotypes. By conducting weighted gene coexpression network analysis of RNA sequencing data from the mPFC of SUS and RES mice, we identified Syt4 as a hub gene in a gene network that was unique to anhedonia. We also confirmed that Syt4 overexpression in the mPFC was pro-susceptible, while Syt4 knockdown was pro-resilient; the pro-susceptible effects of SYT4 were mediated through a reduction in brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signaling in the mPFC. These findings suggest that SYT4-BDNF interactions in the mPFC represent a crucial regulatory mechanism of anhedonic susceptibility to chronic stress.

Cognitive Impairment Mechanism in Patients with Bipolar Disorder

Bipolar disorder (BD) is a common chronic mental disorder usually characterized by manic, hypomanic and depressive episodes. Patients diagnosed with BD have cognitive impairments in both the mood attack and remission stages, that is impairment of attention, memory and executive function. Up till the present moment, the causative mechanisms of cognitive impairment in BD patients remain poorly understood. Several studies have demonstrated that cognitive impairment in patients with bipolar disorder is not associated with a single factor, but with gene polymorphism, brain structural and functional variables, inflammatory and metabolic factors. Herein, we reviewed and summarized the recent reports on cognitive impairment mechanisms in patients with BD. To prevent or alleviate cognitive damage at an early stage, we propose that future research should focus on investigating the pathological mechanism of specific cognitive dimension damage as well as the pathological mechanism network between the damage of each dimension. It is crucial to recognize mechanisms of cognitive impairment for improving the symptoms and prognosis of BD patients, restoring their social function and integration.

Effect of schizophrenia risk gene polymorphisms on cognitive and neural plasticity

A recent Chinese genome-wide association study found evidence for 58 out of the 128 schizophrenia-associated variants previously discovered in Western samples by the Schizophrenia Working Group of the Psychiatric Genomics Consortium (PGC). However, the functional impact of these trans-ancestry genome-wide single-nucleotide polymorphisms (SNPs) is not clear. In the current study, we examined the roles of trans-ancestry SNPs in cognitive and neural plasticity. We first performed a behavioral study of 547 healthy volunteers, who received month-long working memory training, and working memory capability assessment both before and after the training. A separate sample of 101 subjects received the same training and received fMRI scans during a working memory task, both before and after the training. The behavioral study found a significant association between the polygenic risk score (PRS) and behavioral plasticity, with higher schizophrenia risk scores being linked to less plasticity. At the SNP level, rs36068923 showed a significant signal, with the risk allele being associated with less plasticity. The fMRI study further found that the PRS and rs36068923 polymorphism were associated with training-induced changes in striatal activation, with higher PRS and the risk allele of rs36068923 being linked to less brain plasticity. In sum, this study found that a high genetic risk for schizophrenia was associated with less plasticity at both behavioral and neural levels. These results provide new insights into the neural and cognitive mechanisms linking genes to schizophrenia.

Brain gyrification in bipolar disorder: a systematic review of neuroimaging studies

Bipolar disorder (BD) is a severe mental illness with a strong genetic component. Genetic variations have been involved in the risk of this disorder, including those mediating brain function and neurodevelopment. Early neurodevelopment and neuroprogression processes could be reflected in brain gyrification patterns and help optimize the prediction and diagnosis of such disorders that is often delayed. Previous neuroimaging studies using this measure in patients with bipolar disorder revealed controversial results. This systematic review aimed to summarize available neuroimaging investigations on gyrification in BD compared to healthy controls (HC) and/or other psychiatric groups. Fourteen studies including 733 patients with BD, 585 patients with schizophrenia (SCZ), 90 with schizoaffective disorder (SZA), and 1380 healthy subjects were identified. Overall, a heterogeneous pattern of gyrification emerged between patients with BD and HC. Interestingly, increased gyrification or no differences were also observed in patients with BD compared to those with the schizophrenia-spectrum disorders. Furthermore, relatives of patients with BD showed lower or no differences in gyrification compared to healthy subjects without a family history of affective illness. Differences in the design and in methodological approaches could have contributed to the heterogeneity of the findings. The current review supports an altered brain gyrification pattern that underlies the pathophysiology of BD spanning large anatomical and functional neural networks, associated with altered cognitive functioning, difficulties in processing and affective regulation, and clinical symptoms. Longitudinal studies are needed to test different bipolar phenotypes and pharmacological effects on gyrification.

Possible Modulatory Role of ARC Gene Variants in Mood Disorders

OBJECTIVE

The genetic background of mood disorders is gradually emerging through the use of large multicenter samples but a detailed phenotyping is complementary in elucidating the role of modulating variants.

METHODS

In the present paper we focused on the possible modulatory effects of ARC gene variants on two independent mood disorder samples of European (n = 246 bipolar disorder) and Korean (n = 132 bipolar disorder; n = 242 major depressive disorder [MDD]) ancestry.

RESULTS

No result survived Bonferroni correction, however we evidenced promising trend toward possible association between ARC gene variants and mood disorder phenotypes. In particular, we evidenced weak correlations of ARC single nucleotide polymorphisms with depressive symptoms severity (evaluated through Hamilton depression rating scale scores) in the MDD Korean (rs7465272) and European (rs11167152) samples. Additionally rs10110456 was found to be related to Family History, while rs7465272 was related to suicide risk in the Korean sample. Finally, rs7465272 was associated with body mass index in the European sample.

CONCLUSION

Overall, ARC gene variants may have a partial role in modulatory effect on treatment efficacy or phenotypes of mood disorders. Further studies, on larger samples may provide a better understanding on the role of ARC gene variants in the symptom severity and treatment outcomes in patients with mood disorders.

Potential interactions among single nucleotide polymorphisms in bone- and cartilage-related genes in skeletal malocclusions

OBJECTIVE

To investigate SNPs in bone- and cartilage-related genes and their interaction in the aetiology of sagittal and vertical skeletal malocclusions.

SETTINGS AND SAMPLE POPULATION

This study included 143 patients and classified as follows: skeletal class I (n = 77), class II (n = 47) and class III (n = 19); maxillary retrusion (n = 39), protrusion (n = 52) and well-positioned maxilla (n = 52); mandibular retrognathism (n = 50), prognathism (n = 50) and well-positioned mandible (n = 43); normofacial (n = 72), dolichofacial (n = 55) and brachyfacial (n = 16).

MATERIALS AND METHODS

Steiner's ANB, SNA, SNB angles and Ricketts' NBa-PtGn angle were measured to determine the skeletal malocclusion and the vertical pattern. Nine SNPs in BMP2, BMP4, SMAD6, RUNX2, WNT3A and WNT11 were genotyped. Chi-squared test was used to compare genotypes among the groups. Multifactor dimensionality reduction (MDR) and binary logistic regression analysis, both using gender and age as co-variables, were also used. We performed Bonferroni correction for multiple testing.

RESULTS

Significant associations at P < .05 were observed for SNPs rs1005464 (P = .042) and rs235768 (P = .021) in BMP2 with mandibular retrognathism and for rs59983488 (RUNX2) with maxillary protrusion (P = .04) as well as for rs708111 (WNT3A) with skeletal class III (P = .02; dominant model), rs1533767 (WNT11) with a brachyfacial skeletal pattern (P = .01, OR = 0.10; dominant model) and for rs3934908 (SMAD6) with prognathism (P = .02; recessive model). After the Bonferroni correction, none of the SNPs remained associated. The MDR predicted some interaction for skeletal class II, dolichofacial and brachyfacial phenotypes.

CONCLUSION

Our results suggest that SNPs in BMP2, BMP4, SMAD6, RUNX2, WNT3A and WNT11 could be involved in the aetiology of sagittal and vertical malocclusions.

Identification of key pathways and genes responsible for aggressive behavior

Aggression is a complex behavior, underpinned by cross talk between several biomolecules. To date a composite molecular network of the behavioral disorder has not been constructed. The present study aims to develop the same from the system network analyses recruiting genes with empirical evidence demonstrating their role in the incidence and progression of aggression. In short, 327 genes were recruited in the study after extensive literature survey and subsequent shortlisting by sieving out the comorbidities like cancer and other pathological and physiological ailments, other languages and repeated citations. Subsequent String network analysis coalesces 275 genes in a network with 2223 edges. The developed network was then subjected to delineate modules using MCODE which via gene clustering on the basis of gene ontology segregate all genes into 14 modules. Of these, as expected top 5 modules involved entailing of neuronal signaling pathways with redundant repetitions. Finally, 10 genes (known) were picked randomly, accounting average module size, and subjected to the network analysis with 100,000 bootstrap replicates. This results in the detection of certain novel genes that lacks empirical evidence for their association with the aggression. Amongst those, most notable are genes involved in protein turnover regulation like UBC, UBA, mitogenic proteins such as Rho and Myc, transcription factors like Tp53. The findings in turn fill caveats in the molecular resolution of cross talk that underscore the development of aggressive behavior and may then be exploited as screening biomarker and/or therapeutic intervention for aggression.

ZNF804A Gene Variants Have a Cross-diagnostic Influence on Psychosis and Treatment Improvement in Mood Disorders

Objective

Genetic variations in the gene encoding zinc finger protein 804A gene (ZNF804A) have been associated with major depression and bipolar disorder. In this work we focused on the potential influence of ZNF804A variations on the risk of developing specific sub-phenotypes as well as the individual response to available treatments.

Methods

We used two samples of different ethnic origin: a Korean sample, composed by 242 patients diagnosed with major depression and 132 patients diagnosed with bipolar disorder and 326 healthy controls; an Italian sample composed 151 major depression subjects, 189 bipolar disorder subjects and 38 outpatients diagnosed for a primary anxiety disorder.

Results

Our analyses reported an association of rs1344706 with psychotic phenotype in the cross-diagnostic pooled sample (geno p = 4.15 × 10⁻⁴, allelic p = 1.06 × 10⁻⁴). In the cross-diagnosis Italian sample but not in the Korean one, rs7597593 was involved with depressive symptoms improvement after treatment (geno p = 0.025, allelic p = 0.007).

Conclusion

The present study evidenced the role of ZNF804A alterations in symptoms improvement after treatment. Both manic and depressive symptoms seem to be modulated by ZNF804A, though the latter was observed in the bipolar pooled sample only. The role of this factor is likely related to synaptic development and maintenance; however, further analyses will be needed to better understand the molecular mechanics involved with ZNF804A.

Proof-of-concept study of a multi-gene risk score in adolescent bipolar disorder

BACKGROUND

Few studies have examined multiple genetic variants concurrently for the purpose of classifying bipolar disorder (BD); the literature among youth is particularly sparse. We selected 35 genetic variants, previously implicated in BD or associated characteristics, from which to identify the most robustly predictive group of genes.

METHODS

215 Caucasian adolescents (114 BD and 101 healthy controls (HC), ages 13-20 years) were included. Psychiatric diagnoses were determined based on semi-structured diagnostic interviews. Genomic DNA was extracted from saliva for genotyping. Two models were used to calculate a multi-gene risk score (MGRS). Model 1 used forward and backward regressions, and model 2 used a PLINK generated method.

RESULTS

In model 1, GPX3 rs3792797 was significant in the forward regression, DRD4 exonIII was significant in the backward regression; IL1β rs16944 and DISC1 rs821577 were significant in both the forward and backward regressions. These variants are involved in dopamine neurotransmission; inflammation and oxidative stress; and neuronal development. Model 1 MGRS did not significantly discriminate between BD and HC. In model 2, ZNF804A rs1344706 was significantly associated with BD; however, this association did not predict diagnosis when entered into the weighted model.

LIMITATIONS

This study was limited by the number of genetic variants examined and the modest sample size.

CONCLUSIONS

Whereas regression approaches identified four genetic variants that significantly discriminated between BD and HC, those same variants no longer discriminated between BD and HC when computed as a MGRS. Future larger studies are needed evaluating intermediate phenotypes such as neuroimaging and blood-based biomarkers.

Association between CANCA1C gene rs1034936 polymorphism and alcohol dependence in bipolar disorder

INTRODUCTION

Bipolar disorder (BD) is a highly heritable and disabling mental illness, commonly associated with substance abuse, being alcohol abuse the most frequent. Comorbid BD and substance abuse disorders are often associated with high levels of health service utilization and destabilization of the course of illness resulting in poor treatment outcomes. Although recent genome-wide association studies have detected a number of risk genes for BD, the data is still sparse and inconclusive for those genes that may contribute to the increased risk of comorbid alcohol abuse (AA) in BD. The primary aim of the present study was to investigate the effects of 46 single-nucleotide polymorphisms (SNPs) within eight genes on different phenotypes of BD patients, such as comorbid alcohol abuse. We further assessed clinical variables associated with AA.

METHODS

One-hundred fifty-eight BD I and II patients were enrolled in a naturalistic cohort study. Genomic DNA of 92 patients was extracted from whole blood using standard procedures and 46 tag SNPs in eight genes of interest (ANK, CACNA1C, CACNB2, FKBP5, GRM7, ITIH3, SYNE1 and TCF4) were genotyped.

RESULTS

Seventy-one patients out of 158 (45%) satisfied diagnostic criteria for comorbid AA. Among 46 SNPs analyzed, the only SNP associated with comorbid AA was rs1034936 polymorphism in the CANCA1C gene. This polymorphism was also associated with lifetime cocaine abuse, manic switch and current atypical antipsychotics.

CONCLUSIONS

Our findings suggest a role of rs1034936 CACNA1C gene variant in BD-AA group. Despite their preliminary nature, the present results may provide new insight on mechanisms underlying AA in BD.

Plasma microRNA Array Analysis Identifies Overexpressed miR-19b-3p as a Biomarker of Bipolar Depression Distinguishing From Unipolar Depression

OBJECTIVES

The clinical characteristics of bipolar disorder (current major depressive episode) (BD) overlap with unipolar depressive disorder (UD), which makes it difficult to perform an accurate diagnosis. We identified plasma microRNAs (miRNAs) that distinguished BD from UD and explored the relationship between miRNA expression levels and clinical characteristics.

METHODS

Total miRNAs from blood plasma from seven UD patients, seven BD patients, and six controls were analyzed. The identified miRNAs were validated in a separate population group. Depression severity and early life adversities were assessed. Bioinformatic analysis was conducted to investigate the target genes that were identified and the pathways associated with the altered miRNAs.

RESULTS

Compared to controls, 42 miRNAs were differentially expressed in patients. miR-19b-3p, miR-3921, and miR-1180-3p were selected to validate the microarray results. Only miR-19b-3p was validated as down-regulated in patients. The primary predicted genes associated with miR-19b-3p were MAPK1, PTEN, and PRKAA1. The most relevant KEGG pathways included mTOR, FoxO, and the PI3-K/Akt signaling pathway. BD patients were more likely to have higher expression levels of miR-19b-3p and more severe childhood trauma experience compared to UD patients.

CONCLUSIONS

Plasma miR-19b-3p is a potential non-invasive biomarker that might be useful in distinguishing UD from BD. miR-19b3p was predicted to be involved in the pathway of inflammatory dysregulation associated with experiencing early childhood trauma.

FKBP5 Gene Variants May Modulate Depressive Features in Bipolar Disorder

BACKGROUND

Previous evidence suggested the possible association of FK506 binding protein 5 (FKBP5) gene variants in bipolar disorder (BPD).

OBJECTIVE

Given the need of refinement of the findings obtained in large but poorly phenotyped samples, this study investigated the possible role of variants within FKBP5 in a small but deeply phenotyped BPD sample.

METHODS

A sample (N = 131) of bipolar patients were investigated with 10 polymorphisms within the FKBP5 gene. A control sample (N = 65) was also used for the analyses. Treatment response and remission of symptoms were evaluated using of the Hamilton Depression Rating Scale (HDRS), Hamilton Anxiety Rating Scale (HARS), and Young Mania Rating Scale (YMRS). The same analyses were also performed on the depressive subsample of BPD (D.BPD).

RESULTS

rs3800373 was associated with disorder risk in the depressive BPD subsample with the G allele being more frequent in subjects with a D.BPD phenotype. This was the only association that survived statistical correction.

CONCLUSIONS

rs3800373 FKBP5 may increase the risk of developing predominantly depressed BPD, probably through the creation of an enhancer consensus sequence in the 3'UTR of the gene, thus potentially increasing its expression. This finding seems to be partially supported by literature data, which evidenced increased levels of FKBP5 in psychiatric subjects.

Horizontal and vertical integrative analysis methods for mental disorders omics data

In recent biomedical studies, omics profiling has been extensively conducted on various types of mental disorders. In most of the existing analyses, a single type of mental disorder and a single type of omics measurement are analyzed. In the study of other complex diseases, integrative analysis, both vertical and horizontal integration, has been conducted and shown to bring significantly new insights into disease etiology, progression, biomarkers, and treatment. In this article, we showcase the applicability of integrative analysis to mental disorders. In particular, the horizontal integration of bipolar disorder and schizophrenia and the vertical integration of gene expression and copy number variation data are conducted. The analysis is based on the sparse principal component analysis, penalization, and other advanced statistical techniques. In data analysis, integration leads to biologically sensible findings, including the disease-related gene expressions, copy number variations, and their associations, which differ from the “benchmark” analysis. Overall, this study suggests the potential of integrative analysis in mental disorder research.

Genes Involved in Neurodevelopment, Neuroplasticity and Major Depression: No Association for CACNA1C, CHRNA7 and MAPK1

Objective

Genetics factors are likely to play a role in the risk, clinical presentation and treatment outcome in major depressive disorder (MDD). In this study, we investigated the role of three candidate genes for MDD; calcium voltage-gated channel subunit alpha1 C (CACNA1C ), cholinergic receptor nicotinic alpha 7 subunit (CHRNA7 ), and mitogen-activated protein kinase 1 (MAPK1).

Methods

Two-hundred forty-two MDD patients and 326 healthy controls of Korean ancestry served as samples for the analyses. Thirty-nine single nucleotide polymorphisms (SNPs) within CACNA1C, CHRNA7, and MAPK1 genes were genotyped and subsequently tested for association with MDD (primary analysis) and other clinical features (symptoms’ severity, age of onset, history of suicide attempt, treatment outcome) (secondary analyses). Single SNPs, haplotypes and epistatic analyses were performed.

Results

Single SNPs were not associated with disease risk and clinical features. However, a combination of alleles (haplotype) within MAPK1 was found associated with MDD-status. Secondary analyses detected a possible involvement of CACNA1C haplotype in resistance to antidepressant treatment.

Conclusion

These data suggest a role for MAPK1 and CACNA1C in MDD risk and treatment resistance, respectively. However, since many limitations characterize the analysis, the results must be considered with great caution and verified.

Identification of the Key Genes of Autism Spectrum Disorder Through Protein-Protein Interaction Network

Background:

Currently, the prevalence of autism spectrum disorder (ASD) is increasing, which widely spurs the interest in the molecular investigation. Thereby, a better understanding of the given disorder mechanisms is likely to be achieved. Bioinformatics suiting protein-protein interactions analysis via the application of high-throughput studies, such as protein array, is one of these achievements.

Materials and Methods:

The gene expression data from Gene Expression Omnibus (GEO) database were downloaded, and the expression profile of patients with developmental delay and autistic features were analyzed via Cytoscape and its relevant plug-ins.

Results:

Our findings indicated that EGFR, ACTB, RHOA, CALM1, MAPK1, and JUN genes as the hub-bottlenecks and their related terms could be important in ASD risk. In other words, any expression modification in these genes could trigger dysfunctions in the corresponding biological processes.

Conclusion:

We suggest that differentially expressed genes could be used as suitable targets for ASD after being validated.

Neuroplasticity, Neurotransmission and Brain-Related Genes in Major Depression and Bipolar Disorder: Focus on Treatment Outcomes in an Asiatic Sample

Introduction

Mood disorders are common and disabling disorders. Despite the availability of over 100 psychotropic compounds, only one-third of patients benefit from first-line treatments. Over the past 20 years, many studies have focused on the biological factors modulating disease risk and response to treatments, but with still inconclusive data. In order to improve our current knowledge, in this study, we investigated the role of a set of genes involved in different pathways (neurotransmission, neuroplasticity, circadian rhythms, transcription factors, signal transduction and cellular metabolism) in the treatment outcome of major depressive disorder (MDD) and bipolar disorder (BD) after naturalistic pharmacological treatment.

Methods

Totals of 242 MDD, 132 BD patients and 326 healthy controls of Asian ethnicity (Koreans) were genotyped for polymorphisms within 19 genes. Response and remission after 6–8 weeks of treatment with antidepressants and mood stabilizers were evaluated. In secondary analyses, genetic associations with disease risk and some disease-associated features (age of onset, suicide attempt and psychotic BD) were also tested.

Results

None of the variants within the investigated genes was significantly associated with treatment outcomes. Some marginal association (uncorrected p < 0.01) was observed for HTR2A, BDNF, CHL1, RORA and HOMER1 SNPs. In secondary analyses, HTR2A (rs643627, p = 0.002) and CHL1 (rs4003413, p = 0.002) were found associated with risk for BD, HOMER1 (rs6872497, p = 0.002) with lifetime history of suicide attempt in patients, and RORA with early onset and presence of psychotic features in BD. Marginal results were also observed for ST8SIA2 and COMT.

Discussion

Despite limitations linked to multiple testing on small samples, methodological shortcomings and small significance of the findings, this study may support the involvement of some candidate genes in the outcomes of treatments for mood disorders, as well as in BD risk and other disease features.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0781-2) contains supplementary material, which is available to authorized users.