Association study of CREB1 with Major Depressive Disorder and related phenotypes

Altered Expression of Neuroplasticity-Related Genes in Alcohol Addiction and Treatment

Alcohol use disorder's complexity arises from genetic and environmental factors, with alcohol metabolism genes and neurotransmitter pathways being critical. This study aims to analyze synaptic plasticity gene expression changes in individuals with AUD in order to study their contribution to AUD development and to identify potential biomarkers of treatment response. RNA was extracted from whole peripheral blood (20 patients, 10 healthy controls), before and after treatment (Qiagen AllPrep RNA/DNA Mini Kit), and the gene expression of 84 genes related to neuroplasticity was studied using the RT2 Profiler for Human Synaptic Plasticity RT-PCR Array (PAHS-126ZA, Qiagen), comparing AUD patients to control and responders to non-responders. The potential prognostic/predictive biomarkers were searched using machine learning models. A total of 35 dysregulated genes were found in AUD patients. EPHB2, EGR, and AKT1 were increased, while TIMP1, NCAM1, and GRM2 were decreased. Responders showed distinct gene expression profiles at baseline. After treatment, the expression of 57 genes was normalized, while NCAM1, GRM2, and BDNF showed the most significant recovery. EGR4, INHBA, and NCAM1 emerged as potential biomarkers to predict treatment success. These results indicate that gene profiles in peripheral blood can serve as prognostic markers for the prognosis and treatment of AUD, although further validation is required.

Astrocytic CREB in Nucleus Accumbens Promotes Susceptibility to Chronic Stress

BACKGROUND

Increasing evidence implicates astrocytes in stress and depression in both rodent models and human major depressive disorder. Despite this, little is known about the transcriptional responses to stress of astrocytes within the nucleus accumbens (NAc), a key brain reward region, and their influence on behavioral outcomes.

METHODS

We used whole-cell sorting, RNA sequencing, and bioinformatic analyses to investigate the NAc astrocyte transcriptome in male mice in response to chronic social defeat stress (CSDS). Immunohistochemistry was used to determine stress-induced changes in astrocytic CREB (cAMP response element binding protein) within the NAc. Finally, astrocytic regulation of depression-like behavior was investigated using viral-mediated manipulation of CREB in combination with CSDS.

RESULTS

We found a robust transcriptional response in NAc astrocytes to CSDS in stressed mice, with changes seen in both stress-susceptible and stress-resilient animals. Bioinformatic analysis revealed CREB, a transcription factor widely studied in neurons, as one of the top-predicted upstream regulators of the NAc astrocyte transcriptome, with opposite activation states implicated in resilient versus susceptible mice. This bioinformatic deduction was confirmed at the protein level with immunohistochemistry. Moreover, NAc astrocyte morphological complexity correlated with CREB activation and was reduced selectively in astrocytes of resilient mice. Viral overexpression of CREB selectively in NAc astrocytes promoted susceptibility to chronic stress.

CONCLUSIONS

Together, our data demonstrate that the astrocyte transcriptome responds robustly to CSDS and that transcriptional regulation in astrocytes contributes to depressive-like behaviors. A better understanding of transcriptional regulation in astrocytes may reveal unknown molecular mechanisms underlying neuropsychiatric disorders.

Astrocytic CREB in nucleus accumbens promotes susceptibility to chronic stress

Background

Increasing evidence implicates astrocytes in stress and depression in both rodent models and human Major Depressive Disorder (MDD). Despite this, little is known about the transcriptional responses to stress of astrocytes within the nucleus accumbens (NAc), a key brain reward region, and their influence on behavioral outcomes.

Methods

We used whole cell sorting, RNA-sequencing, and bioinformatic analyses to investigate the NAc astrocyte transcriptome in male mice in response to chronic social defeat stress (CSDS). Immunohistochemistry was used to determine stress-induced changes in astrocytic CREB within the NAc. Finally, astrocytic regulation of depression-like behavior was investigated using viral-mediated manipulation of CREB in combination with CSDS.

Results

We found a robust transcriptional response in NAc astrocytes to CSDS in stressed mice, with changes seen in both stress-susceptible and stress-resilient animals. Bioinformatic analysis revealed CREB, a transcription factor widely studied in neurons, as one of the top-predicted upstream regulators of the NAc astrocyte transcriptome, with opposite activation states seen in resilient versus susceptible mice. This bioinformatic result was confirmed at the protein level with immunohistochemistry. Viral overexpression of CREB selectively in NAc astrocytes promoted susceptibility to chronic stress.

Conclusions

Together, our data demonstrate that the astrocyte transcriptome responds robustly to CSDS and, for the first time, that transcriptional regulation in astrocytes contributes to depressive-like behaviors. A better understanding of transcriptional regulation in astrocytes may reveal unknown molecular mechanisms underlying neuropsychiatric disorders.

Emotional dysregulation, alexithymia and neuroticism: a systematic review on the genetic basis of a subset of psychological traits

Neuroticism, alexithymia and emotion dysregulation are key traits and known risk factors for several psychiatric conditions. In this systematic review, the aim is to evaluate the genetic contribution to these psychological phenotypes. A systematic review of articles found in PubMed was conducted. Search terms included 'genetic', 'GWAS', 'neuroticism', 'alexithymia' and 'emotion dysregulation'. Risk of bias was assessed utilizing the STREGA checklist. Two hundred two papers were selected from existing literature based on the inclusion and exclusion criteria. Among these, 27 were genome-wide studies and 175 were genetic association studies. Single gene association studies focused on selected groups of genes, mostly involved in neurotransmission, with conflicting results. GWAS studies on neuroticism, on the other hand, found several relevant and replicated intergenic and intronic loci affecting the expression and regulation of crucial and well-known genes (such as DRD2 and CRHR1). Mutations in genes coding for trascriptional factors were also found to be associated with neuroticism (DCC, XKR6, TCF4, RBFOX1), as well as a noncoding regulatory RNA (LINC00461). On the other hand, little GWAS data are available on alexythima and emotional dysregulation.

Network-Based Pharmacology Study Reveals Protein Targets for Medical Benefits and Harms of Cannabinoids in Humans

This network-based pharmacology study intends to uncover the underlying mechanisms of cannabis leading to a therapeutic benefit and the pathogenesis for a wide range of diseases claimed to benefit from or be caused by the use of the cannabis plant. Cannabis contains more than 600 chemical components. Among these components, cannabinoids are well-known to have multifarious pharmacological activities. In this work, twelve cannabinoids were selected as active compounds through text mining and drug-like properties screening and used for initial protein-target prediction. The disease-associated biological functions and pathways were enriched through GO and KEGG databases. Various biological networks [i.e., protein-protein interaction, target-pathway, pathway-disease, and target-(pathway)-target interaction] were constructed, and the functional modules and essential protein targets were elucidated through the topological analyses of the networks. Our study revealed that eighteen proteins (CAT, COMT, CYP17A1, GSTA2, GSTM3, GSTP1, HMOX1, AKT1, CASP9, PLCG1, PRKCA, PRKCB, CYCS, TNF, CNR1, CNR2, CREB1, GRIN2B) are essential targets of eight cannabinoids (CBD, CBDA, Δ9-THC, CBN, CBC, CBGA, CBG, Δ8-THC), which involve in a variety of pathways resulting in beneficial and adverse effects on the human body. The molecular docking simulation confirmed that these eight cannabinoids bind to their corresponding protein targets with high binding affinities. This study generates a verifiable hypothesis of medical benefits and harms of key cannabinoids with a model which consists of multiple components, multiple targets, and multiple pathways, which provides an important foundation for further deployment of preclinical and clinical studies of cannabis.

Genetic and clinical determinants of mizoribine pharmacokinetics in renal transplant recipients

AIM

Mizoribine (MZR) is an immunosuppressant for the prevention of allograft rejection in Asian countries, but the great variability in pharmacokinetics (PK) limits its clinical use. This study was to explore genetic and clinical factors that affect the MZR PK process.

METHODS

Blood samples and clinical data were collected from 60 Chinese renal transplant recipients. MZR plasma concentration was measured at pre-dose (0 h) and 0.5, 1, 2, 3, 4, 5, 6, 8, and 12 h post-dose by high performance liquid chromatography with an ultraviolet detector. PK parameters were calculated by non-compartmental analysis. High-throughput sequenced single nucleotide polymorphism was applied screening possible genetic factors.

RESULTS

Extensive inter-individual MZR PK differences were reflected in the process of elimination (k_e, CL/F, MRT and t_1/2) and intestinal absorption (C_max and T_max), as well as in the dose-normalized exposure (AUC_0-12h/D). From 146 SNPs within 39 genes screened, AUC_0-12h/D was found higher in recipients with CREB1 rs11904814 TT than with G allele carriers (3.135 ± 0.928 versus 2.084 ± 0.379 μg h ml^-1 mg^-1, p = 0.007). Recipients with SLC28A3 rs10868138 TT had lower t_1/2 as compared to C allele carriers (0.728 ± 0.189 versus 0.951 ± 0.196 h, p = 0.001). Serum creatinine (SCr) explained 35.5% of C₀/D variability (p < 0.001). Pure effects of genotypes CREB1 and SLC28A3 were 13.7% (p = 0.004) and 17.5% (p = 0.001) for AUC_0-12h/D and t_1/2, respectively. When additionally taking SCr into models, CREB1 and SLC28A3 genotypes explained 20.0% (p = 0.038) and 46.5% (p < 0.001) of AUC_0-12h/D and t_1/2 variability, respectively.

CONCLUSION

CREB1 and SLC28A3 genotypes, as well as SCr, are identified as determinants in predicting inter-individual MZR PK differences in renal transplant recipients.

VRK2, a Candidate Gene for Psychiatric and Neurological Disorders

Recent large-scale genetic approaches, such as genome-wide association studies, have identified multiple genetic variations that contribute to the risk of mental illnesses, among which single nucleotide polymorphisms (SNPs) within or near the vaccinia related kinase 2 (VRK2) gene have gained consistent support for their correlations with multiple psychiatric and neurological disorders including schizophrenia (SCZ), major depressive disorder (MDD), and genetic generalized epilepsy. For instance, the genetic variant rs1518395 in VRK2 showed genome-wide significant associations with SCZ (35,476 cases and 46,839 controls, p = 3.43 × 10-8) and MDD (130,620 cases and 347,620 controls, p = 4.32 × 10-12) in European populations. This SNP was also genome-wide significantly associated with SCZ in Han Chinese population (12,083 cases and 24,097 controls, p = 3.78 × 10-13), and all associations were in the same direction of allelic effects. These studies highlight the potential roles of VRK2 in the central nervous system, and this gene therefore might be a good candidate to investigate the shared genetic and molecular basis between SCZ and MDD, as it is one of the few genes known to show genome-wide significant associations with both illnesses. Furthermore, the VRK2 gene was found to be involved in multiple other congenital deficits related to the malfunction of neurodevelopment, adding further support for the involvement of this gene in the pathogenesis of these neurological and psychiatric illnesses. While the precise function of VRK2 in these conditions remains unclear, preliminary evidence suggests that it may affect neuronal proliferation and migration via interacting with multiple essential signaling pathways involving other susceptibility genes/proteins for psychiatric disorders. Here, we have reviewed the recent progress of genetic and molecular studies of VRK2, with an emphasis on its role in psychiatric illnesses and neurological functions. We believe that attention to this important gene is necessary, and further investigations of VRK2 may provide hints into the underlying mechanisms of SCZ and MDD.

GNB3 and CREB1 gene polymorphisms combined with negative life events increase susceptibility to major depression in a Chinese Han population

BACKGROUND

Major depression (MD) is caused by a combination of genetic and environmental factors. In this study we investigated the interaction of variations in the G-protein beta 3 subunit (GNB3) and cAMP response element binding protein 1 (CREB1) genes with negative life events in the pathogenesis of MD. One GNB3 polymorphism (rs5443) and four CREB1 polymorphisms (rs2253206, rs2551941, rs6740584, rs11904814) were investigated based on known associations with MD.

METHODS

512 patients with MD and 513 control subjects were genotyped. The frequency and severity of negative life events were measured by the Life Events Scale (LES). Gene-environment interactions (G×E) were assessed using the generalized multifactor dimensionality reduction (GMDR) method.

RESULTS

Differences in GNB3 rs5443 allele frequencies and genotype distributions were observed between MD patients and controls. Significant G×E interactions were detected between negative life events and genotypic variation of all five single nucleotide polymorphisms (SNPs). Individuals carrying the T- allele of rs5443 (CC), A- allele of rs2253206 (GG), T- allele of rs2551941 (AA), C- allele of rs6740584 (TT) or G- allele of rs11904814 (TT) conferred susceptibility to MD in subjects only exposed to high-negative life events. However, individuals with the T+ allele of rs5443 (CT, TT) were susceptible to MD when exposed to low negative life events.

CONCLUSIONS

Interactions between GNB3, CREB1 and negative life events were revealed. Further evidence is provided about the role of the environment in genetic vulnerability to MD.

Consensus paper of the WFSBP Task Force on Genetics: Genetics, epigenetics and gene expression markers of major depressive disorder and antidepressant response

Major depressive disorder (MDD) is a heritable disease with a heavy personal and socio-economic burden. Antidepressants of different classes are prescribed to treat MDD, but reliable and reproducible markers of efficacy are not available for clinical use. Further complicating treatment, the diagnosis of MDD is not guided by objective criteria, resulting in the risk of under- or overtreatment. A number of markers of MDD and antidepressant response have been investigated at the genetic, epigenetic, gene expression and protein levels. Polymorphisms in genes involved in antidepressant metabolism (cytochrome P450 isoenzymes), antidepressant transport (ABCB1), glucocorticoid signalling (FKBP5) and serotonin neurotransmission (SLC6A4 and HTR2A) were among those included in the first pharmacogenetic assays that have been tested for clinical applicability. The results of these investigations were encouraging when examining patient-outcome improvement. Furthermore, a nine-serum biomarker panel (including BDNF, cortisol and soluble TNF-α receptor type II) showed good sensitivity and specificity in differentiating between MDD and healthy controls. These first diagnostic and response-predictive tests for MDD provided a source of optimism for future clinical applications. However, such findings should be considered very carefully because their benefit/cost ratio and clinical indications were not clearly demonstrated. Future tests may include combinations of different types of biomarkers and be specific for MDD subtypes or pathological dimensions.

CREB1 gene polymorphisms combined with environmental risk factors increase susceptibility to major depressive disorder (MDD)

Major depressive disorder (MDD) is one of the most severe psychiatric disorders. The objective of this study was to explore the effects of CREB1 gene polymorphisms on risk of developing MDD and the joint effects of gene-environment interactions. Genotyping was performed by Taqman allelic discrimination assay among 586 patients and 586 healthy controls. A significant impact on rs6740584 genotype distribution was found for childhood trauma (P = 0.015). We did not find an association of CREB1 polymorphisms with MDD susceptibility. However, we found a significantly increased risk associated with the interactions of CREB1 polymorphisms and drinking (OR = 11.67, 95% CI = 2.52-54.18; OR = 11.52, 95% CI = 2.55-51.95 for rs11904814; OR = 4.18, 95% CI = 1.87-9.38; OR = 5.02, 95% CI = 2.27-11.14 for rs6740584; OR = 7.58, 95% CI = 2.05-27.98; OR = 7.59, 95% CI = 2.12-27.14 for rs2553206; OR = 8.37, 95% CI = 3.02-23.23; OR = 7.84, 95% CI = 2.93-20.98 for rs2551941). We also noted that CREB polymorphisms combined with family harmony and childhood trauma conferred increased susceptibility for MDD. In conclusion, polymorphisms in the CREB gene may not be independently associated with MDD risk, but they are likely to confer increased susceptibility by interacting with environmental risk factors in the Chinese population.

Association study of CREB1 polymorphisms and suicidality in MDD: results from a European multicenter study on treatment resistant depression

PURPOSE

Mood disorders are present in more than 90% of suicides, and a genetic vulnerability to suicidality is well established. Numerous lines of evidence relate the transcription factor Cyclic adenosine monophosphate Response Element Binding protein (CREB1) to suicide, and to the aetiology of major depressive disorder (MDD). Our aim was to test for association between CREB1 single nucleotide polymorphisms (SNPs) and both suicide risk (SR) and a personal history of suicide attempt (SA) in MDD patients.

MATERIALS AND METHODS

A sample of 250 MDD patients collected in the context of a European multicenter resistant depression study and treated with antidepressants over a period of at least 4 weeks were genotyped for five CREB1 SNPs (rs2709376, rs2253206, rs7569963, rs7594560, and rs4675690). To assess suicidality, the Mini International Neuropsychiatric Interview (MINI) and the Hamilton Rating Scale for Depression (HAM-D) were applied.

RESULTS

Neither single-marker nor haplotypic association were found between SR and/or a personal history of SA with any of the investigated SNPs after multiple testing correction. For females, an association between rs2709376 and a personal history of SA was found (p = 0.016), however not resisting multiple testing correction.

CONCLUSIONS

Although we found significant CREB1 single marker association with a personal history of SA in female MDD patients, this finding could not be confirmed in haplotypic analyses after multiple testing correction. Larger well-defined cohorts are required to confirm or refute a possible association of CREB1 and SA in female MDD patients.

Association of CREB1 gene polymorphism with drug seeking behaviour in eastern Indian addicts

cAMP response element binding protein (CREB) is a major transcription factor which plays an important role in a wide array of cellular functions. CREB also has a significant function in developing substance abuse. A study was undertaken to identify the single nucleotide polymorphisms (SNP) at selective areas of CREB1 gene in heroin as well as in alcohol addicts in comparison with control population. One hundred and forty control subjects, 112 heroin and 102 alcoholics, all male and residing in Kolkata, a city in eastern India participated in the study. SNPs from several exonic regions of CREB1 gene were assessed to investigate possible associations with addiction. One SNP in exon 3, rs35349697, demonstrated a significant correlation with opioid addiction as well as with alcohol addiction. A novel SNP, also located in exon 3, was identified which showed epistatic interaction with rs35349697 to decrease susceptibility to narcotic addiction in the population. The study is the first report on the identification of a role of CREB1 gene polymorphism with addiction.

Case-control association study of 14 variants of CREB1, CREBBP and CREM on diagnosis and treatment outcome in major depressive disorder and bipolar disorder

Some evidence suggests an association between genetic variants within the cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), CREB binding protein (CREBBP) and cAMP response element-modulator (CREM) and several psychiatric disorders. The present study investigated whether some single nucleotide polymorphisms (SNPs) within these genes could be associated with major depressive disorder (MDD) and bipolar disorder (BD) and whether they could predict clinical outcomes in Korean in-patients treated with antidepressants and mood stabilizers, respectively. The sample comprised 145 patients with MDD, 132 patients with BD and 170 psychiatrically healthy controls. Participants were genotyped for 14 SNPs within CREB1, CREBBP and CREM. Baseline and final clinical measures, including the Montgomery-Åsberg Depression Rating Scale and Young Mania Rating Scale for patients with MDD and BD, respectively, were recorded. All p-values were 2-tailed, and statistical significance was conservatively set at the 0.006 level in order to reduce the likelihood of false positive results. We failed to observe any association of the 14 SNPs genotypes or alleles with clinical improvement, response and remission rates as well as final outcomes in any of such disorders. Our findings suggest that the 14 SNP under investigation in our study do not influence diagnosis and treatment response in patients with MDD and BD. However, taking into account the several limitations of our study, further research is needed to draw more definitive conclusions.

A comprehensive network and pathway analysis of candidate genes in major depressive disorder

BACKGROUND

Numerous genetic and genomic datasets related to complex diseases have been made available during the last decade. It is now a great challenge to assess such heterogeneous datasets to prioritize disease genes and perform follow up functional analysis and validation. Among complex disease studies, psychiatric disorders such as major depressive disorder (MDD) are especially in need of robust integrative analysis because these diseases are more complex than others, with weak genetic factors at various levels, including genetic markers, transcription (gene expression), epigenetics (methylation), protein, pathways and networks.

RESULTS

In this study, we proposed a comprehensive analysis framework at the systems level and demonstrated it in MDD using a set of candidate genes that have recently been prioritized based on multiple lines of evidence including association, linkage, gene expression (both human and animal studies), regulatory pathway, and literature search. In the network analysis, we explored the topological characteristics of these genes in the context of the human interactome and compared them with two other complex diseases. The network topological features indicated that MDD is similar to schizophrenia compared to cancer. In the functional analysis, we performed the gene set enrichment analysis for both Gene Ontology categories and canonical pathways. Moreover, we proposed a unique pathway crosstalk approach to examine the dynamic interactions among biological pathways. Our pathway enrichment and crosstalk analyses revealed two unique pathway interaction modules that were significantly enriched with MDD genes. These two modules are neuro-transmission and immune system related, supporting the neuropathology hypothesis of MDD. Finally, we constructed a MDD-specific subnetwork, which recruited novel candidate genes with association signals from a major MDD GWAS dataset.

CONCLUSIONS

This study is the first systematic network and pathway analysis of candidate genes in MDD, providing abundant important information about gene interaction and regulation in a major psychiatric disease. The results suggest potential functional components underlying the molecular mechanisms of MDD and, thus, facilitate generation of novel hypotheses in this disease. The systems biology based strategy in this study can be applied to many other complex diseases.

The CREB1-BDNF-NTRK2 pathway in depression: multiple gene-cognition-environment interactions

BACKGROUND

The neuroplastic pathway, which includes cyclic adenosine monophosphate response element-binding protein 1 (CREB1), brain-derived neurotrophic factor (BDNF), and its receptor (neurotrophic tyrosine kinase receptor, type 2 [NTRK2]), plays a crucial role in the adaptation of brain to stress, and thus variations of these genes are plausible risk factors for depression.

METHODS

A population-based sample was recruited, subsets of which were interviewed and underwent functional magnetic resonance imaging. We investigated the association of nine polymorphisms throughout the CREB1-BDNF-NTRK2 pathway with lifetime depression, rumination, current depression severity, negative life events, and sad face emotion processing in a three-level design.

RESULTS

In the population study, BDNF-rs6265 and CREB1-rs2253206 major alleles were significantly associated with rumination and through rumination with current depression severity. However, childhood adversity increased the risk of lifetime depression in the minor allele carriers of BDNF-rs6265 and CREB1-rs2253206 and in alleles of six other single nucleotide polymorphisms (SNPs). We validated our findings in the interviewed subjects using structural equation modeling. Finally, using functional magnetic resonance imaging, we found that viewing sad faces evoked greater activity in depression-related areas in healthy control subjects possessing the minor alleles of BDNF-rs6265 and CREB1-rs2253206.

CONCLUSIONS

Genetic variation associated with reduced function in the CREB1-BDNF-NTRK2 pathway has multiple, sometimes opposing, influences on risk mechanisms of depression, but almost all the SNPs studied amplified the effect of childhood adversity. The use of cognitive and neural intermediate phenotypes together with a molecular pathway approach may be critical to understanding how genes influence risk of depression.

Pharmacogenetics of antidepressants

Up to 60% of depressed patients do not respond completely to antidepressants (ADs) and up to 30% do not respond at all. Genetic factors contribute for about 50% of the AD response. During the recent years the possible influence of a set of candidate genes as genetic predictors of AD response efficacy was investigated by us and others. They include the cytochrome P450 superfamily, the P-glycoprotein (ABCB1), the tryptophan hydroxylase, the catechol-O-methyltransferase, the monoamine oxidase A, the serotonin transporter (5-HTTLPR), the norepinephrine transporter, the dopamine transporter, variants in the 5-hydroxytryptamine receptors (5-HT1A, 5-HT2A, 5-HT3A, 5-HT3B, and 5-HT6), adrenoreceptor beta-1 and alpha-2, the dopamine receptors (D2), the G protein beta 3 subunit, the corticotropin releasing hormone receptors (CRHR1 and CRHR2), the glucocorticoid receptors, the c-AMP response-element binding, and the brain-derived neurotrophic factor. Marginal associations were reported for angiotensin I converting enzyme, circadian locomotor output cycles kaput protein, glutamatergic system, nitric oxide synthase, and interleukin 1-beta gene. In conclusion, gene variants seem to influence human behavior, liability to disorders and treatment response. Nonetheless, gene × environment interactions have been hypothesized to modulate several of these effects.