Sequence variations in CREB1 cosegregate with depressive disorders in women

Neonatal nociceptive stimulation results in pain sensitization, reduction of hippocampal 5-HT1A receptor, and p-CREB expression in adult female rats

Painful invasive procedures are often performed on newborns admitted to intensive care units (ICU). The acute and long-term effects caused by these stimuli can be investigated in animal models, such as newborn rats. Previous studies have shown that animals subjected to nociceptive stimuli in the neonatal period show sex-specific behavioral changes such as signs of anxiety or depression. Under the same conditions, neonatal stimuli also provoke an increase in the rate of neurogenesis and cell activation in the hippocampal dentate gyrus. So, this study aims to identify the possible roles of central monoamines, receptor expression (5-HT1A), and signaling factors (p-CREB) underlying the long-term effects of neonatal nociceptive stimulation. For this, noxious stimulation was induced by intra-plantar injection of Complete Freund´s adjuvant (CFA) on the postnatal day 1 (P1) or 8 (P8). Control animals were not stimulated. On P75 the behavioral tests were conducted (hotplate and elevated plus maze), followed by sacrifice and molecular studies. Our results showed that neonatal nociceptive stimulation alters pain sensitization specially in females, while stimulation on P1 increases pain threshold, P8-stimulated animals respond with reduced pain threshold (P < 0.001). Hippocampal expression of 5-HT1A receptor and p-CREB were reduced in P8 F group (P < 0.001) in opposition to the increased utilization rate of dopamine and serotonin in this group (P < 0.05). This study shows sex- and age-specific responses of signaling pathways within the hippocampus accompanied by altered behavioral repertoire, at long-term after neonatal painful stimulation.

LncRNA TDRKH-AS1 promotes breast cancer progression via the miR-134-5p/CREB1 axis

BACKGROUND

Breast cancer (BC) is a prevalent malignancy with complex etiology and varied clinical behavior. Long non-coding RNAs (lncRNAs) have emerged as key regulators in cancer progression, including BC. Among these, lncRNA TDRKH-AS1 has been implicated in several cancers, but its role in BC remains unclear.

METHODS

We conducted a comprehensive investigation to elucidate the role of TDRKH-AS1 in BC. Clinical samples were collected from BC patients, and BC cell lines were cultured. Bioinformatics analysis using the starBase database was carried out to assess TDRKH-AS1 expression levels in BC tissue samples. Functional experiments, including knockdown, colony formation, CCK-8, Transwell, and wound-healing assays, were conducted to determine the role of TDRKH-AS1 in BC cell proliferation and invasion. Luciferase reporter and RIP assays were used to examine the interactions between TDRKH-AS1 and miR-134-5p. In addition, the downstream target gene of miR-134-5p, cAMP response element-binding protein 1 (CREB1), was identified and studied using various methods, including RT-qPCR, immunoprecipitation, and rescue experiments. In vivo experiments using mouse tumor xenograft models were conducted to examine the role of TDRKH-AS1 in BC tumorigenesis.

RESULTS

TDRKH-AS1 was found to be significantly upregulated in BC tissues and cell lines. High TDRKH-AS1 expression correlated with advanced BC stages and worse patient outcomes. Knockdown of TDRKH-AS1 led to decreased BC cell proliferation and invasion. Mechanistically, TDRKH-AS1 acted as a sponge for miR-134-5p, thereby reducing the inhibitory effects of miR-134-5p on CREB1 expression. Overexpression of CREB1 partially rescued the effects of TDRKH-AS1 knockdown in BC cells. In vivo studies further confirmed the tumor-promoting role of TDRKH-AS1 in BC.

CONCLUSIONS

Our study unveiled a novel regulatory axis involving TDRKH-AS1, miR-134-5p, and CREB1 in BC progression. TDRKH-AS1 functioned as an oncogenic lncRNA by promoting BC cell proliferation and invasion through modulation of the miR-134-5p/CREB1 axis. These findings highlighted TDRKH-AS1 as a potential diagnostic biomarker and therapeutic target for BC treatment.

Potential cross-species correlations in social hierarchy and memory between mice and young children

Social hierarchy is associated with various phenotypes. Although memory is known to be important for hierarchy formation, the difference in memory abilities between dominant and subordinate individuals remains unclear. In this study, we examined memory performance in mice with different social ranks and found better memory abilities in dominant mice, along with greater long-term potentiation and higher memory-related gene expression in the hippocampus. Daily injection of memory-improving drugs could also enhance dominance. To validate this correlation across species, through inventory, behavioral and event-related potential studies, we identified better memory abilities in preschool children with higher social dominance. Better memory potentially helped children process dominance facial cues and learn social strategies to acquire higher positions. Our study shows a remarkable similarity between humans and mice in the association between memory and social hierarchy and provides valuable insight into social interactions in young animals, with potential implications for preschool education.

Memory performance and hippocampal memory-related gene expression are shown to both be increased in more dominant mice, with memory-improving drugs enhancing dominant behaviour. The data also suggests that children with better memory can recognise dominance more easily, demonstrating a potential cross-species correlation in the association between memory and social hierarchy.

Effects of aging on the motor, cognitive and affective behaviors, neuroimmune responses and hippocampal gene expression

The known effects of aging on the brain and behavior include impaired cognition, increases in anxiety and depressive-like behaviors, and reduced locomotor activity. Environmental exposures and interventions also influence brain functions during aging. We investigated the effects of normal aging under controlled environmental conditions and in the absence of external interventions on locomotor activity, cognition, anxiety and depressive-like behaviors, immune function and hippocampal gene expression in C57BL/6 mice. Healthy mice at 4, 9, and 14 months of age underwent behavioral testing using an established behavioral battery, followed by cellular and molecular analysis using flow cytometry, immunohistochemistry, and quantitative PCR. We found that 14-month-old mice showed significantly reduced baseline locomotion, increased anxiety, and impaired spatial memory compared to younger counterparts. However, no significant differences were observed for depressive-like behavior in the forced-swim test. Microglia numbers in the dentate gyrus, as well as CD8+ memory T cells increased towards late middle age. Aging processes exerted a significant effect on the expression of 43 genes of interest in the hippocampus. We conclude that aging is associated with specific changes in locomotor activity, cognition, anxiety-like behaviors, neuroimmune responses and hippocampal gene expression.

Neglected Functions of TFCP2/TFCP2L1/UBP1 Transcription Factors May Offer Valuable Insights into Their Mechanisms of Action

In recent years, the TFCP2 (transcription factor cellular promoter 2)/TFCP2L1 (TFCP2-like 1)/UBP1 (upstream binding protein 1) subfamily of transcription factors has been attracting increasing attention in the scientific community. These factors are very important in cancer, Alzheimer’s disease, and other human conditions, and they can be attractive targets for drug development. However, the interpretation of experimental results is complicated, as in principle, any of these factors could substitute for the lack of another. Thus, studying their hitherto little known functions should enhance our understanding of mechanisms of their functioning, and analogous mechanisms might govern their functioning in medically relevant contexts. For example, there are numerous parallels between placental development and cancer growth; therefore, investigating the roles of TFCP2, TFCP2L1, and UBP1 in the placenta may help us better understand their functioning in cancer, as is evidenced by the studies of various other proteins and pathways. Our review article aims to call the attention of the scientific community to these neglected functions, and encourage further research in this field. Here, we present a systematic review of current knowledge of the TFCP2/TFCP2L1/UBP1 subfamily in reproduction, embryonic development, renal function, blood-pressure regulation, brain function, and other processes, where their involvement has not been studied much until now.

Identification and replication of RNA-Seq gene network modules associated with depression severity

Genomic variation underlying major depressive disorder (MDD) likely involves the interaction and regulation of multiple genes in a network. Data-driven co-expression network module inference has the potential to account for variation within regulatory networks, reduce the dimensionality of RNA-Seq data, and detect significant gene-expression modules associated with depression severity. We performed an RNA-Seq gene co-expression network analysis of mRNA data obtained from the peripheral blood mononuclear cells of unmedicated MDD (n = 78) and healthy control (n = 79) subjects. Across the combined MDD and HC groups, we assigned genes into modules using hierarchical clustering with a dynamic tree cut method and projected the expression data onto a lower-dimensional module space by computing the single-sample gene set enrichment score of each module. We tested the single-sample scores of each module for association with levels of depression severity measured by the Montgomery-Åsberg Depression Scale (MADRS). Independent of MDD status, we identified 23 gene modules from the co-expression network. Two modules were significantly associated with the MADRS score after multiple comparison adjustment (adjusted p = 0.009, 0.028 at 0.05 FDR threshold), and one of these modules replicated in a previous RNA-Seq study of MDD (p = 0.03). The two MADRS-associated modules contain genes previously implicated in mood disorders and show enrichment of apoptosis and B cell receptor signaling. The genes in these modules show a correlation between network centrality and univariate association with depression, suggesting that intramodular hub genes are more likely to be related to MDD compared to other genes in a module.

Association analysis between mitogen-activated protein/extracellular signal-regulated kinase (MEK) gene polymorphisms and depressive disorder in the Han Chinese population

BACKGROUND

Recent research findings suggest that BDNF and BDNF signaling pathways participate in the development of major depressive disorder. Mitogen-activated extracellular signal-regulated kinase (MEK) is the most important kinase in the extracellular signal-regulated kinase pathway, and the extracellular signal-regulated kinase pathway is the key signaling pathway of BDNF, so it may play a role in development of depressive disorder. The aim of this study is to investigate the association between polymorphisms of the MAP2K1 (also known as MEK) gene and depressive disorder.

RESULTS

Three single nucleotide polymorphisms (SNPs), were significantly associated with depressive disorder: rs1549854 (p = 0.006), rs1432441 (p = 0.025), and rs7182853 (p = 0.039). When subdividing the sample by gender, two of the SNPs remained statistically associated with depressive disorder in females: rs1549854 (p = 0.013) and rs1432441 (p = 0.04).

CONCLUSION

The rs1549854 and rs1432441 polymorphisms of the MAP2K1 gene may be associated with major depressive disorder, especially in females. This study is the first to report that the MAP2K1 gene may be a genetic marker for depressive disorder.

CREB1 regulates glucose transport of glioma cell line U87 by targeting GLUT1

Glioma is stemmed from the glial cells in the brain, which is accounted for about 45% of all intracranial tumors. The characteristic of glioma is invasive growth, as well as there is no obvious boundary between normal brain tissue and glioma tissue, so it is difficult to resect completely with worst prognosis. The metabolism of glioma is following the Warburg effect. Previous researches have shown that GLUT1, as a glucose transporter carrier, affected the Warburg effect, but the molecular mechanism is not very clear. CREB1 (cAMP responsive element-binding protein1) is involved in various biological processes, and relevant studies confirmed that CREB1 protein regulated the expression of GLUT1, thus mediating glucose transport in cells. Our experiments mainly reveal that the CREB1 could affect glucose transport in glioma cells by regulating the expression of GLUT1, which controlled the metabolism of glioma and affected the progression of glioma.

Highly polygenic architecture of antidepressant treatment response: Comparative analysis of SSRI and NRI treatment in an animal model of depression

Response to antidepressant (AD) treatment may be a more polygenic trait than previously hypothesized, with many genetic variants interacting in yet unclear ways. In this study we used methods that can automatically learn to detect patterns of statistical regularity from a sparsely distributed signal across hippocampal transcriptome measurements in a large-scale animal pharmacogenomic study to uncover genomic variations associated with AD. The study used four inbred mouse strains of both sexes, two drug treatments, and a control group (escitalopram, nortriptyline, and saline). Multi-class and binary classification using Machine Learning (ML) and regularization algorithms using iterative and univariate feature selection methods, including InfoGain, mRMR, ANOVA, and Chi Square, were used to uncover genomic markers associated with AD response. Relevant genes were selected based on Jaccard distance and carried forward for gene-network analysis. Linear association methods uncovered only one gene associated with drug treatment response. The implementation of ML algorithms, together with feature reduction methods, revealed a set of 204 genes associated with SSRI and 241 genes associated with NRI response. Although only 10% of genes overlapped across the two drugs, network analysis shows that both drugs modulated the CREB pathway, through different molecular mechanisms. Through careful implementation and optimisations, the algorithms detected a weak signal used to predict whether an animal was treated with nortriptyline (77%) or escitalopram (67%) on an independent testing set. The results from this study indicate that the molecular signature of AD treatment may include a much broader range of genomic markers than previously hypothesized, suggesting that response to medication may be as complex as the pathology. The search for biomarkers of antidepressant treatment response could therefore consider a higher number of genetic markers and their interactions. Through predominately different molecular targets and mechanisms of action, the two drugs modulate the same Creb1 pathway which plays a key role in neurotrophic responses and in inflammatory processes. © 2016 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by Wiley Periodicals, Inc.

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.

The genetic overlap between mood disorders and cardiometabolic diseases: a systematic review of genome wide and candidate gene studies

Meta-analyses of genome-wide association studies (meta-GWASs) and candidate gene studies have identified genetic variants associated with cardiovascular diseases, metabolic diseases and mood disorders. Although previous efforts were successful for individual disease conditions (single disease), limited information exists on shared genetic risk between these disorders. This article presents a detailed review and analysis of cardiometabolic diseases risk (CMD-R) genes that are also associated with mood disorders. First, we reviewed meta-GWASs published until January 2016, for the diseases 'type 2 diabetes, coronary artery disease, hypertension' and/or for the risk factors 'blood pressure, obesity, plasma lipid levels, insulin and glucose related traits'. We then searched the literature for published associations of these CMD-R genes with mood disorders. We considered studies that reported a significant association of at least one of the CMD-R genes and 'depression' or 'depressive disorder' or 'depressive symptoms' or 'bipolar disorder' or 'lithium treatment response in bipolar disorder', or 'serotonin reuptake inhibitors treatment response in major depression'. Our review revealed 24 potential pleiotropic genes that are likely to be shared between mood disorders and CMD-Rs. These genes include MTHFR, CACNA1D, CACNB2, GNAS, ADRB1, NCAN, REST, FTO, POMC, BDNF, CREB, ITIH4, LEP, GSK3B, SLC18A1, TLR4, PPP1R1B, APOE, CRY2, HTR1A, ADRA2A, TCF7L2, MTNR1B and IGF1. A pathway analysis of these genes revealed significant pathways: corticotrophin-releasing hormone signaling, AMPK signaling, cAMP-mediated or G-protein coupled receptor signaling, axonal guidance signaling, serotonin or dopamine receptors signaling, dopamine-DARPP32 feedback in cAMP signaling, circadian rhythm signaling and leptin signaling. Our review provides insights into the shared biological mechanisms of mood disorders and cardiometabolic diseases.

Impairments in dendrite morphogenesis as etiology for neurodevelopmental disorders and implications for therapeutic treatments

Dendrite morphology is pivotal for neural circuitry functioning. While the causative relationship between small-scale dendrite morphological abnormalities (shape, density of dendritic spines) and neurodevelopmental disorders is well established, such relationship remains elusive for larger-scale dendrite morphological impairments (size, shape, branching pattern of dendritic trees). Here, we summarize published data on dendrite morphological irregularities in human patients and animal models for neurodevelopmental disorders, with focus on autism and schizophrenia. We next discuss high-risk genes for these disorders and their role in dendrite morphogenesis. We finally overview recent developments in therapeutic attempts and we discuss how they relate to dendrite morphology. We find that both autism and schizophrenia are accompanied by dendritic arbor morphological irregularities, and that majority of their high-risk genes regulate dendrite morphogenesis. Thus, we present a compelling argument that, along with smaller-scale morphological impairments in dendrites (spines and synapse), irregularities in larger-scale dendrite morphology (arbor shape, size) may be an important part of neurodevelopmental disorders' etiology. We suggest that this should not be ignored when developing future therapeutic treatments.

Differential hippocampal gene expression and pathway analysis in an etiology-based mouse model of major depressive disorder

We have recently reported the creation and initial characterization of an etiology-based recombinant mouse model of a severe and inherited form of Major Depressive Disorder (MDD). This was achieved by replacing the corresponding mouse DNA sequence with a 6-base DNA sequence from the human CREB1 promoter that is associated with MDD in individuals from families with recurrent, early-onset MDD (RE-MDD). In the current study, we explored the effect of the pathogenic Creb1 allele on gene expression in the mouse hippocampus, a brain region that is altered in structure and function in MDD. Mouse whole-genome profiling was performed using the Illumina MouseWG-6 v2.0 Expression BeadChip microarray. Univariate analysis identified 269 differentially-expressed genes in the hippocampus of the mutant mouse. Pathway analyses highlighted 11 KEGG pathways: the phosphatidylinositol signaling system, which has been widely implicated in MDD, Bipolar Disorder, and the action of mood stabilizers; gap junction and long-term potentiation, which mediate cognition and memory functions often impaired in MDD; cardiac muscle contraction, insulin signaling pathway, and three neurodegenerative brain disorders (Alzheimer's, Parkinson's, and Huntington's Diseases) that are associated with MDD; ribosome and proteasome pathways affecting protein synthesis/degradation; and the oxidative phosphorylation pathway that is key to energy production. These findings illustrate the merit of this congenic C57BL/6 recombinant mouse as a model of RE-MDD, and demonstrate its potential for highlighting molecular and cellular pathways that contribute to the biology of MDD. The results also inform our understanding of the mechanisms that underlie the comorbidity of MDD with other disorders.

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.

Allelic differences between Europeans and Chinese for CREB1 SNPs and their implications in gene expression regulation, hippocampal structure and function, and bipolar disorder susceptibility

Bipolar disorder (BD) is a polygenic disorder that shares substantial genetic risk factors with major depressive disorder (MDD). Genetic analyses have reported numerous BD susceptibility genes, while some variants, such as single-nucleotide polymorphisms (SNPs) in CACNA1C have been successfully replicated, many others have not and subsequently their effects on the intermediate phenotypes cannot be verified. Here, we studied the MDD-related gene CREB1 in a set of independent BD sample groups of European ancestry (a total of 64,888 subjects) and identified multiple SNPs significantly associated with BD (the most significant being SNP rs6785[A], P=6.32 × 10(-5), odds ratio (OR)=1.090). Risk SNPs were then subjected to further analyses in healthy Europeans for intermediate phenotypes of BD, including hippocampal volume, hippocampal function and cognitive performance. Our results showed that the risk SNPs were significantly associated with hippocampal volume and hippocampal function, with the risk alleles showing a decreased hippocampal volume and diminished activation of the left hippocampus, adding further evidence for their involvement in BD susceptibility. We also found the risk SNPs were strongly associated with CREB1 expression in lymphoblastoid cells (P<0.005) and the prefrontal cortex (P<1.0 × 10(-6)). Remarkably, population genetic analysis indicated that CREB1 displayed striking differences in allele frequencies between continental populations, and the risk alleles were completely absent in East Asian populations. We demonstrated that the regional prevalence of the CREB1 risk alleles in Europeans is likely caused by genetic hitchhiking due to natural selection acting on a nearby gene. Our results suggest that differential population histories due to natural selection on regional populations may lead to genetic heterogeneity of susceptibility to complex diseases, such as BD, and explain inconsistencies in detecting the genetic markers of these diseases among different ethnic populations.

Genes showing altered expression in the medial preoptic area in the highly social maternal phenotype are related to autism and other disorders with social deficits

Background

The mother-child relationship is the most fundamental social bond in mammals, and previous studies indicate that the medial preoptic area (MPOA) contributes to this increase in sociability. It is possible that the same genes that lead to elevated sociability in one condition (the maternal state) might also be dysregulated in some disorders with social deficits (e.g. autism). In this study, we examined whether there was enrichment (greater than chance overlap) for social deficit disorder related genes in MPOA microarray results between virgin and postpartum female mice. We utilized microarrays to assess large scale gene expression changes in the MPOA of virgin and postpartum mice. The Modular Single Set Enrichment Test (MSET) was used to determine if mental health disorder related genes were enriched in significant microarray results. Additional resources, such as ToppCluster, NIH DAVID, and weighted co-expression network analysis (WGCNA) were used to analyze enrichment for specific gene clusters or indirect relationships between significant genes of interest. Finally, a subset of microarray results was validated using quantitative PCR.

Results

Significant postpartum MPOA microarray results were enriched for multiple disorders that include social deficits, including autism, bipolar disorder, depression, and schizophrenia. Together, 98 autism-related genes were identified from the significant microarray results. Further, ToppCluser and NIH DAVID identified a large number of postpartum genes related to ion channel activity and CNS development, and also suggested a role for microRNAs in regulating maternal gene expression. WGCNA identified a module of genes associated with the postpartum phenotype, and identified indirect links between transcription factors and other genes of interest.

Conclusion

The transition to the maternal state involves great CNS plasticity and increased sociability. We identified multiple novel genes that overlap between the postpartum MPOA (high sociability) and mental health disorders with low sociability. Thus, the activity or interactions of the same genes may be altering social behaviors in different directions in different conditions. Maternity also involves elevated risks for disorders, including depression, psychosis, and BPD, so identification of maternal genes common to these disorders may provide insights into the elevated vulnerability of the maternal brain.

Brain-derived neurotrophic factor gene polymorphisms, neurotransmitter levels, and depressive symptoms in an elderly population

A large number of studies have examined associations between brain-derived neurotrophic factor (BDNF) gene polymorphisms and depressive symptoms. However, results still remain controversial. Recent studies suggested a significant age and gender effect on the heritability of depression. The potential neurobiological pathways that could possibly mediate this relationship have not been examined so far. Since BDNF is involved in the regulation of neurotransmitter production, a mediating role of neurotransmitters seems plausible. The present study aims to examine the association between three common BDNF single-nucleotid polymorphisms (SNPs; rs7103411, rs7124442, and rs6265) and depressive symptoms in a community-based elderly population taking into account the serum levels of four neurotransmitters, serotonin, dopamine, adrenalin, and noradrenalin, as potential mediating factors. We also examined whether age and gender had a modifying effect on this association. We collected and analyzed the genetic and laboratory data as well as Center for Epidemiologic Studies-Depression scores of 350 community-dwelling elderly individuals (aged 65+ years). We found that the BDNF rs6265 polymorphism was related to the severity of depressive symptoms, and that this association was independent of neurotransmitter levels. Stratified analyses showed that this association was restricted to older individuals (≥74 years) and men. The associations of SNPs rs7103411 or rs7124442 SNP with depressive symptoms were not statistically significant. This study importantly adds to the existing literature by affirming previous assumptions on an age and gender difference in the relation between BDNF genotype and depression. We moreover first-time report a missing mediating role of neurotransmitters in this association.

Cellular plasticity and resilience and the pathophysiology of severe mood disorders

Recent advances in the identification of the neural circuits, neurochemicals, and signal transduction mechanisms involved in the pathophysiology and treatment of mood disorders have led to much progress toward understanding the roles of genetic factors and psychosocial stressors. The monoaminergic neurotransmitter systems have received the most attention, partly because of the observation that effective antidepressant drugs exert their primary biochemical effects by regulating intrasynaptic concentrations of serotonin and norepinephrine. Furthermore, the monoaminergic systems are extensively distributed throughout the network of limbic, striatal, and prefrontal cortical neuronal circuits thought to support the behavioral and visceral manifestations of mood disorders. Increasing numbers of neuroimaging, neuropathological, and biochemical studies indicate impairments in cellular plasticity and resilience in patients who suffer from severe, recurrent mood disorders. In this paper, we describe studies identifying possible structural, functional, and cellular abnormalities associated with depressive disorders, which are potentially the cellular underpinnings of these diseases. We suggest that drugs designed to enhance cellular plasticity and resilience, and attenuate the activity of maladaptive stress-responsive systems, may be useful for the treatment of severe mood disorders.

European Group for the Study of Resistant Depression (GSRD)--where have we gone so far: review of clinical and genetic findings

The primary objective of this review is to give an overview of the main findings of the European multicenter project "Patterns of Treatment Resistance and Switching Strategies in Affective Disorder", performed by the Group for the Study of Resistant Depression (GSRD). The aim was to study methodological issues, operational criteria, clinical characteristics, and genetic variables associated with treatment resistant depression (TRD), that is failure to reach response after at least two consecutive adequate antidepressant trials. The primary findings of clinical variables associated with treatment resistance include comorbid anxiety disorders as well as non-response to the first antidepressant received lifetime. Although there is a plethora of hints in textbooks that switching the mechanism of action should be obtained in case of nonresponse to one medication, the results of the GSRD challenge this notion by demonstrating in retrospective and prospective evaluations that staying on the same antidepressant mechanism of action for a longer time is more beneficial than switching, however, when switching is an option there is no benefit to switch across class. The GSRD candidate gene studies found that metabolism status according to cytochrome P450 gene polymorphisms may not be helpful to predict response and remission rates to antidepressants. Significant associations with MDD and antidepressant treatment response were found for COMT SNPs. Investigating the impact of COMT on suicidal behaviour, we found a significant association with suicide risk in MDD patients not responding to antidepressant treatment, but not in responders. Further significant associations with treatment response phenotypes were found with BDNF, 5HTR2A and CREB1. Additional investigated candidate genes were DTNBP1, 5HT1A, PTGS2, GRIK4 and GNB3.

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.

Gender-specific role of the protein tyrosine phosphatase receptor type R gene in major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a common, chronic, and recurrent mental disease affecting millions of individuals worldwide. The precise mechanism by which the illness is developed remains unknown, but it has been accepted that a genetic component is very likely to be involved. Studies of the pathogenesis of MDD have implicated a reduced activity of the extracellular regulated kinase (ERK) signaling system. Protein tyrosine phosphatase, receptor type R (PTPRR) is a key negative regulator of the ERK signaling pathway and its expression is regulated by androgen. Therefore, it is worth testing whether the PTPRR gene could confer a risk of MDD.

METHODS

We genotyped 16 SNPs in the PTPRR locus with the MALDI-TOF-MS-based genotyping protocol in 517 patients with MDD and 455 controls among a Chinese Han population. The UNPHASED program was applied to analyze the genotyping data.

RESULTS

Of the 16 SNPs selected, rs1513105 was the only one showing allelic association (χ2=9.019, p=0.0027) and genotypic association (χ2=8.813, df=2, p=0.012), of which the rs1513105(C) allele was associated with an increased risk of MDD (OR=1.331, 95% CI 1.104-1.604), but the rs1513105 association resulted mainly from female subjects (χ2=12.35, p=0.00044 for allelic association; χ2=11.26, df=2, p=0.0036 for genotypic association).

LIMITATIONS

Replication and functional study may be required to draw a firm conclusion.

CONCLUSIONS

Our results suggest that the PTPRR gene may play a role in conferring risk of MDD in the female subjects.

Early influence of the rs4675690 on the neural substrates of sadness

BACKGROUND

CREB1 has previously been implicated in mood disorders, suicide, and antidepressant response. There is some evidence that the T allele in rs4675690, a single-nucleotide polymorphism near the CREB1 gene, is involved in the modulation of neural responses to negative stimuli. It is not known whether differential brain activity during negative mood state appears early in life in T allele carriers.

METHODS

Functional magnetic resonance imaging (fMRI) was used to measure brain activity, during a transient state of sadness, in children homozygous for the T allele or the C allele. This primary emotion was selected given that it is the prevailing mood in major depressive disorder (MDD). Blood-oxygen-level dependent (BOLD) signal changes were measured while subjects viewed blocks of neutral film excerpts and blocks of sad film excerpts.

RESULTS

There was significantly greater BOLD activation in the TT group, compared to the CC group, in the right dorsal anterior cingulate cortex (Brodmann area [BA 24]), right putamen, right caudate nucleus and left anterior temporal pole (BA 21), when the brain activity associated with the viewing of the emotionally neutral film excerpts was subtracted from that associated with the viewing of the sad film excerpts.

LIMITATIONS

A replication study using larger samples may be required for more definitive conclusions.

CONCLUSIONS

The different pattern of regional brain activation found here during transient sadness - in children carrying the T allele, compared to those carrying the C allele - might increase later in life susceptibility to emotional dysregulation and depressive symptoms.

Replacement of homologous mouse DNA sequence with pathogenic 6-base human CREB1 promoter sequence creates murine model of major depressive disorder

Major depressive disorder (MDD) is a leading cause of disability worldwide. Families with recurrent, early-onset MDD (RE-MDD), a severe, familial form of MDD, have provided an important resource for identifying and characterizing genetic variants that confer susceptibility to MDD and related disorders. Previous studies identified a rare, highly penetrant A(-115)G transition within the human CREB1 promoter that reduced promoter activity in vitro and was associated with depressive disorders in RE-MDD families. The development of an etiology-based recombinant animal model for MDD would facilitate the advancement of our limited understanding of the pathophysiology of MDD, as well as the development of improved treatments. Here we report the construction and initial characterization of a congenic mutant C57BL/6NTac mouse model that carries the human pathogenic sequence at the homologous position of the mouse Creb1 promoter. The recombinant strain exhibited decreases in reproductive capacity and pup survival that may be related to increased infant mortality observed in RE-MDD families; enlargement of the cerebral ventricles; reduced levels of CREB protein in the mouse cerebral cortex, as predicted from transfection experiments employing the pathogenic human CREB1 promoter; and alterations in two standardized behavioral tests, the forced swim and marble burying tests. These initial findings support the pathogenicity of the human A(-115)G promoter variant, and invite further characterization of this etiology-based recombinant animal model for MDD. Human promoter variants that have highly penetrant effects on disease expression provide an attractive opportunity for creating etiology-based mouse models of human diseases, with minimal disruption of the mouse genome.

Effects of the A(-115)G variant on CREB1 promoter activity in two brain cell lines: Interactions with gonadal steroids

Major depressive disorder (MDD) is a leading contributor to disease burden worldwide. Previous genetic studies have revealed significant evidence of linkage of the CREB1 region to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. Systematic resequencing of the CREB1 gene in affected members of these families has identified rare sequence variants at positions -656 and -115 that appear to cosegregate with unipolar mood disorders in two large multigenerational families and three small nuclear families, respectively. Results from previous transfection experiments that employed constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene support the hypothesis that the A(-656) allele contributes to the development of MDD in women by selectively increasing the activity of the CREB1 promoter in brain cell lines exposed to 17 β-estradiol. Analogous transfection experiments described in the current study revealed that the G(-115) promoter variant reduced promoter activity in CATH.a neuronal cells regardless of the hormonal environment, consistent with the observation that increased risk for unipolar mood disorders conferred by this allele was not limited by sex. The effects of CREB1 promoter variants on promoter activity, their influence on the development of mood disorders and related clinical features, and the interaction of their phenotypic expression with sex seem likely to be complex and allele-specific rather than a general property of the CREB1 locus. © 2010 Wiley-Liss, Inc.

Association study of 44 candidate genes with depressive and anxiety symptoms in post-partum women

The post-partum period is a time of extreme vulnerability for a whole spectrum of psychiatric disorders. Delivery may be considered an important risk factor in genetically susceptible women. Five hundred and eight SNPs in 44 genes at candidate pathways putatively related to mood changes after delivery were genotyped in a multicenter cohort of 1804 women from Spain. Participants completed two scales at 2-3 days, 8 weeks, and 32 weeks post-partum, the Edinburgh Post-partum Depression Scale (EPDS) and the Spielberger State-Trait Anxiety Inventory (STAI). Those women who scored 9 or more on EPDS were evaluated for major depression using the Diagnostic Interview for Genetics Studies (DIGS) adapted for post-partum depression. Association with major depression was assessed using likelihood ratio tests under a codominant genotype model. Association with scale scores was tested using linear mixed models to take into account repeated measures over time. Two intronic SNPs, one at the serotonin transporter gene (SLC6A4) and another at dopa decarboxylase (DDC), were significantly associated to STAI anxiety scores after multiple testing correction (nominal P=0.0000513 and 0.000097, respectively). In addition, post hoc analysis at the unphased haplotype level using nominal significant SNPs revealed an association with a combination of three SNPs at protein kinase C, beta (PRKCB) with major depression, significant after multiple testing correction (nominal global P=0.0001596). In conclusion, we detected a role of SLC6A4 in mood changes after stressful events, and revealed new putative associations involving DDC and PRKCB. Therefore, these genes deserve further investigation to confirm these results.

A novel analytical framework for dissecting the genetic architecture of behavioral symptoms in neuropsychiatric disorders

BACKGROUND

For diagnosis of neuropsychiatric disorders, a categorical classification system is often utilized as a simple way for conceptualizing an often complex clinical picture. This approach provides an unsatisfactory model of mental illness, since in practice patients do not conform to these prototypical diagnostic categories. Family studies show notable familial co-aggregation between schizophrenia and bipolar illness and between schizoaffective disorders and both bipolar disorder and schizophrenia, revealing that mental illness does not conform to such categorical models and is likely to follow a continuum encompassing a spectrum of behavioral symptoms.

RESULTS AND METHODOLOGY

We introduce an analytic framework to dissect the phenotypic heterogeneity present in complex psychiatric disorders based on the conceptual paradigm of a continuum of psychosis. The approach identifies subgroups of behavioral symptoms that are likely to be phenotypically and genetically homogenous. We have evaluated this approach through analysis of simulated data with simulated behavioral traits and predisposing genetic factors. We also apply this approach to a psychiatric dataset of a genome scan for schizophrenia for which extensive behavioral information was collected for each individual patient and their families. With this approach, we identified significant evidence for linkage among depressed individuals with two distinct symptom profiles, that is individuals with sleep disturbance symptoms with linkage on chromosome 2q13 and also a mutually exclusive group of individuals with symptoms of concentration problems with linkage on chromosome 2q35. In addition we identified a subset of individuals with schizophrenia defined by language disturbances with linkage to chromosome 2p25.1 and a group of patients with a phenotype intermediate between those of schizophrenia and schizoaffective disorder with linkage to chromosome 2p21.

CONCLUSIONS

The findings presented are novel and demonstrate the efficacy of this approach in detection of genes underlying such complex human disorders as schizophrenia and depression.

A population-based association study of candidate genes for depression and sleep disturbance

The clinical manifestation of depression comprises a variety of symptoms, including early morning awakenings and fatigue, features also indicating disturbed sleep. The presence or absence of these symptoms may reflect differences in neurobiological processes leading to prolonged depression. Several neurobiological mechanisms have been indicated in the induction of depression, including disturbances in serotonergic and glutamatergic neurotransmission and in the action of the hypothalamic-pituitary-adrenal (HPA) axis. The same transmitters have also been linked to sleep regulation. We hypothesized that depression without simultaneous symptoms of disturbed sleep would partly have a different genetic background than depression with symptoms of disturbed sleep. We tested this hypothesis using a systematic population-based association study of 14 candidate genes related to depression and disturbed sleep. Association of genetic variants with either depression alone, depression with early morning awakenings, or depression with fatigue was investigated using permutation-based allelic association analysis of a sample of 1,654 adults recruited from Finland's population-based program. The major findings were associations of TPH2 (rs12229394) with depression accompanied by fatigue in women and CREB1 (rs11904814) with depression alone in men. We also found suggestive associations in women for GAD1, GRIA3, and BDNF with depression accompanied by fatigue, and for CRHR1 with depression accompanied by early morning awakenings. The results indicate sex-dependent and symptom-specific differences in the genetic background of depression. These differences may partially explain the broad spectrum of depressive symptoms, and their systematic monitoring could potentially be used for diagnostic purposes.

Meta-analysis of the BDNF Val66Met polymorphism in major depressive disorder: effects of gender and ethnicity

Brain-derived neurotrophic factor (BDNF) is a nerve growth factor that has antidepressant-like effects in animals and may be implicated in the etiology of mood-related phenotypes. However, genetic association studies of the BDNF Val66Met polymorphism (single nucleotide polymorphism rs6265) in major depressive disorder (MDD) have produced inconsistent results. We conducted a meta-analysis of studies comparing the frequency of the BDNF Val66Met-coding variant in depressed cases (MDD) and nondepressed controls. A total of 14 studies involving 2812 cases with DSM-III or -IV defined MDD and 10 843 nondepressed controls met the inclusion criteria. Analyses were stratified either by gender or ethnicity (Asian and Caucasian) because MDD is more prevalent in women and in Caucasians and because BDNF allele frequencies differ by ethnicity. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were provided for allelic analyses (Met versus Val), as well as for genotypic analyses (Met/Met and Val/Met versus Val/Val). In the total sample, the BDNF Val66Met polymorphism was not significantly associated with depression. However, the gender stratified analyses revealed significant effects in both the allelic and genotypic analyses in men (OR(MET), 95% CI; 1.27 (1.10-1.47); OR(MET/MET), 95% CI; 1.67 (1.19-2.36)). Stratification according to ethnicity did not show significant effects of the Val66Met polymorphism on MDD. Our results suggest that the BDNF Val66Met polymorphism is of greater importance in the development of MDD in men than in women. Future research into gender issues will be of interest.

Genetic linkage of region containing the CREB1 gene to depressive disorders in families with recurrent, early-onset, major depression: a re-analysis and confirmation of sex-specific effect

A previously published model-free linkage analysis of chromosome 2q33-35, highlighted by previous case-control studies and supported by within-family analyses employing the transmission disequilibrium test, revealed evidence of sex-specific linkage of the CREB1-containing region of 2q to unipolar mood disorders among women in 81 recurrent, early-onset, major depressive disorder (RE-MDD) families. Since it has been reported that the LODPAL program from S.A.G.E. v.4.0 used to conduct this previous linkage analysis suffers from an increased type I error rate that is exacerbated by covariates such as sex, we re-analyzed the evidence for this sex-specific linkage result using a simulation approach to estimate the empirical significance of our previous results. The results continue to support sex-specific linkage of the CREB1 region to mood disorders among women from families with RE-MDD. Moreover, these results have been supported by a host of additional published findings that implicate sequence variations in CREB1 in the sex-dependent development of syndromic mood disorders, as well as related clinical features and disorders.

Association study of CREB1 with Major Depressive Disorder and related phenotypes

Cyclic AMP response element binding protein (CREB) has been implicated in behavioral models of anxiety and depression, antidepressant response in humans, and suicide. One group reported a female-specific association of the CREB1 gene in early-onset Major Depressive Disorder (MDD), while another found no evidence of association with this phenotype. In this study, we sought to examine the evidence for association of the CREB1 gene to MDD and related phenotypes. We used multivariate structural equation modeling to identify and select twin pairs that scored at the extremes of a latent genetic risk factor shared by MDD, neuroticism, and several anxiety disorders from the Virginia Twin Registry. Using one member from each of these pairs, the resulting sample of 589 cases (including 473 subjects with lifetime MDD) and 539 controls were entered into a 2-stage association study in which genetic markers were screened in stage 1, the positive results of which were tested for replication in stage 2. Eight SNP markers selected to capture the major allelic variation across the haplotype block containing CREB1 were analyzed for differences between cases and controls. Several markers showed criterion differences between cases and controls in the stage 1 sample with some evidence of sex specific effects. However, none of these markers were significant in stage 2 in either sex individually or combined. Our data suggests that common variations in the CREB1 gene do not appear to increase susceptibility for MDD or related phenotypes.

Sequence variations of ABCB1, SLC6A2, SLC6A3, SLC6A4, CREB1, CRHR1 and NTRK2: association with major depression and antidepressant response in Mexican-Americans

We studied seven genes that reflect events relevant to antidepressant action at four sequential levels: (1) entry into the brain, (2) binding to monoaminergic transporters, and (3) distal effects at the transcription level, resulting in (4) changes in neurotrophin and neuropeptide receptors. Those genes are ATP-binding cassette subfamily B member 1 (ABCB1), the noradrenaline, dopamine, and serotonin transporters (SLC6A2, SLC6A3 and SLC6A4), cyclic AMP-responsive element binding protein 1 (CREB1), corticotropin-releasing hormone receptor 1 (CRHR1) and neurotrophic tyrosine kinase type 2 receptor (NTRK2). Sequence variability for those genes was obtained in exonic and flanking regions. A total of 56 280 000 bp across were sequenced in 536 unrelated Mexican Americans from Los Angeles (264 controls and 272 major depressive disorder (MDD)). We detected in those individuals 419 single nucleotide polymorphisms (SNPs); the nucleotide diversity was 0.00054 + or - 0.0001. Of those, a total of 204 novel SNPs were identified, corresponding to 49% of all previously reported SNPs in those genes: 72 were in untranslated regions, 19 were in coding sequences of which 7 were non-synonymous, 86 were intronic and 27 were in upstream/downstream regions. Several SNPs or haplotypes in ABCB1, SLC6A2, SLC6A3, SLC6A4, CREB1 and NTRK2 were associated with MDD, and in ABCB1, SLC6A2 and NTRK2 with antidepressant response. After controlling for age, gender and baseline 21-item Hamilton Depression Rating Scale (HAM-D21) score, as well as correcting for multiple testing, the relative reduction of HAM-D21 score remained significantly associated with two NTRK2-coding SNPs (rs2289657 and rs56142442) and the haplotype CAG at rs2289658 (splice site), rs2289657 and rs2289656. Further studies in larger independent samples will be needed to confirm these associations. Our data indicate that extensive assessment of sequence variability may contribute to increase understanding of disease susceptibility and drug response. Moreover, these results highlight the importance of direct re-sequencing of key candidate genes in ethnic minority groups in order to discover novel genetic variants that cannot be simply inferred from existing databases.

Unipolar depressive disorders have a common genotype

BACKGROUND

The purpose of this study was to estimate the contribution of genetic, common- and unique environmental factors in the aetiology of unipolar major depression (MD), and to investigate whether the unipolar depressive disorders; MD, atypical depression/depression NOS, dysthymia and depressive adjustment disorder can be viewed as various expressions of an underlying genetic commonality.

METHODS

A sample consisting of same-sexed mono- and dizygotic twins was drawn from in- and outpatient hospital registers (N=303). DSM-III-R criteria were assessed by personal interviews. One hundred and forty-three of the probands fulfilled the criteria for one or another unipolar depressive disorder. Cross-tabulations were used to compare concordance rates for MD and different combinations of MD and other unipolar depressive disorders. Correlations in liability and estimations of the heritability (h(2)) with biometrical model fitting were performed.

RESULTS

Concordance rates were higher among MZ- than among DZ pairs for both MD and all the different combinations of MD and other unipolar depressive disorders. Cross-concordance between MD and other unipolar disorders was observed. In all instances, except for the situation when MD was considered alone, the correlations in liability among MZ pairs were more than twice the correlations in liability among DZ pairs. The heritability of MD was 0.42, of MD+atypical depression 0.51, of MD+atypical depression+dysthymia 0.45 and of MD+atypical depression+dysthymia+depressive adjustment disorder 0.46.

LIMITATION

Probands were not sampled from the general population. Most often the same person interviewed both twins in a pair.

CONCLUSION

Unipolar MD is moderately heritable without significant shared family environmental effects. Unipolar depressive disorders taken together are moderately heritable without any detectable shared family environmental effects. The tendency is towards higher heritability estimates for the combined groups compared to MD alone. The study suggests that the disorders in the unipolar depressive spectrum may be different manifestations of the same genetic liability.

Antiapoptotic and neurotrophic effects of antidepressants: a review of clinical and experimental studies

Recent studies have strengthened the role of the abnormalities in neurotrophic pathways in the pathophysiology of depression. It has been shown that the depletion of growth factors, particularly brain-derived neurotrophic factor, may result in depression-like behavior in animals and may induce cellular changes that are reminiscent of those observed in depressed patients. Some authors even suggested that increased neuronal cell loss may contribute to the pathogenesis of depression. Hence, appreciable interest has been focused on the trophic and antiapoptotic effects of antidepressant drugs. In this paper, we put emphasis on the contribution of hippocampal atrophy, increased cell death and alterations in trophic factors to the pathogenesis of depression and their relationship to the potential of antidepressants to reverse these changes by modulating trophic factor cascades and preventing apoptosis. First, evidences for increased hippocampal atrophy and cell death in depression are discussed, followed by a review of selected studies of special interest that concern antiapoptotic action of antidepressant drugs. Next, depression-related neurotrophic abnormalities and their reversal by antidepressants are depicted. Finally, relationships among neurotrophins, antiapoptotic proteins and antioxidant enzymes in the pathology and treatment of depression are pointed out.

Effects of the G(-656)A variant on CREB1 promoter activity in a neuronal cell line: interactions with gonadal steroids and stress

Major depressive disorder (MDD) constitutes a major public health problem worldwide and affects women twice as frequently as men. Previous genetic studies have revealed significant evidence of linkage of the cAMP-responsive element-binding protein 1 (CREB1) gene region (2q33-35) to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. A rare G-to-A transition at position -656 in the CREB1 promoter co-segregates with mood disorders in women from these families, implicating CREB1 as a sex-related susceptibility gene for unipolar mood disorders. In the current study, the functional significance of the CREB1 promoter variant was determined using transfection experiments that employed plasmid constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene. The results support the hypothesis that the A(-656) allele contributes to the development of MDD in women through selective alteration of CREB1 promoter activity by female gonadal steroids in noradrenergic neuronal cells. Furthermore, exaggeration of these effects during a simulated stress condition may be relevant to reported gene-environment interactions that contribute to the emergence of MDD in clinical populations.

Identification of a CREB-dependent serotonergic pathway and neuronal circuit regulating foraging behavior in Caenorhabditis elegans: a useful model for mental disorders and their treatments?

The cAMP-response element binding protein (CREB)-mediated cell signaling pathway is conserved through evolution and participates in a broad range of complex behaviors of divergent species including man. This study describes the integration of genetic, pharmacologic, and anatomic methods to elucidate a serotonergic signaling pathway by which the CREB homolog CRH-1 controls foraging rate (FR) in the model organism Caenorhabditis elegans, along with the complete neuronal circuit through which this pathway operates. In the anterior afferent arm of the circuit, CRH-1 controls FR by regulating the expression of tph-1, the sole structural gene for tryptophan hydroxylase, in serotonergic sensory (ADF) neurons whose post-synaptic effects are mediated through 5HT(2)-like SER-1 receptors. The posterior afferent limb of the circuit includes an interneuron (RIH) that does not express tph-1 and whose serotonergic phenotype is dependent on the contribution of this neurotransmitter from another source, probably the ADF neurons. The postsynaptic effects of the RIH interneuron are mediated through 5HT(1)-like SER-4 receptors. This model has potential utility for the study of clinical disorders and experimental therapeutics. Furthermore, the discovery of serotonergic neurons that depend on other sources for their neurotransmitter phenotype could provide a mechanism for rapidly altering the number and distribution of serotonergic pathways in developing and adult nervous systems, providing a dimension of functional complexity that has been previously unrecognized.

HPA-axis regulation at in-patient admission is associated with antidepressant therapy outcome in male but not in female depressed patients

A concatenation of data implicates a hyperactivity of the hypothalamus pituitary adrenal (HPA)-axis in the pathogenesis of depression and its normalization as a necessary predecessor of clinical response to antidepressant drugs. In addition, regulation of the HPA-axis has been shown to be dependent on sex hormones. We therefore investigated gender differences in HPA-axis regulation in depression and its normalization during remission of clinical symptoms. We used the combined dexamethasone suppression/CRH stimulation (Dex-CRH) test to evaluate the degree of HPA-axis dysregulation in 194 in-patients with unipolar depression from the Munich Antidepressant Response Signature (MARS) study at both admission and discharge. The Hamilton Depression (HAM-D) Rating Scale was used to monitor clinical response to antidepressant treatment. For both genders, we observed a normalization of HPA-axis dysregulation in remitters but not in non-remitters, both after 5 weeks of treatment and at discharge. The pattern of HPA-axis normalization with remission of depressive symptoms, however, showed gender-specific differences. In male patients, remission after 5 weeks of in-patient treatment was associated with a significantly higher cortisol response in the Dex-CRH test at admission. In female patients, 5-week remitters and non-remitters had a comparable cortisol response at admission. Cortisol response at admission was not correlated with gonadal steroid levels at this time point and the results were similar for pre-menopausal women vs. post-menopausal women. Gender-associated biological characteristics, likely independent of circulating gonadal steroids, thus seem to influence HPA-axis regulation in depression. In male patients, a single measure of HPA-axis dysregulation at admission may serve as a predictor of response to antidepressant treatment in addition to the previously reported repeated measure of the Dex-CRH test.

Effects of the G(-656)A variant on CREB1 promoter activity in a glial cell line: interactions with gonadal steroids and stress

Major depressive disorder (MDD) constitutes a major public health problem worldwide and affects women twice as frequently as men. Previous genetic studies have revealed significant evidence of linkage of the CREB1 region to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. A rare G to A transition at position -656 in the CREB1 promoter cosegregates with mood disorders in women from these families, implicating CREB1 as a sex-related susceptibility gene for unipolar mood disorders. In the current study, the functional significance of the CREB1 promoter variant was determined using transfection experiments that employed constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene. The results support the hypothesis that the A(-656) allele contributes to the development of MDD in women by selectively altering the activity of the CREB1 promoter in glial cells exposed to 17 beta-estradiol. Furthermore, the exaggeration of this effect during a simulated stress condition may be relevant to reported gene-environment interactions that contribute to the emergence of MDD in clinical populations. The results of in silico analysis revealed four putative binding sites for transcription factors that are affected by the G to A transition at position -656, of which CP2 best fit the experimental observations.

Lithium response and genetic variation in the CREB family of genes

Bipolar disorder (BD) is a severe psychiatric disorder that affects 1% of the population. Recently, there have been many attempts to identify specific genes that are involved in BD; however, the task of finding susceptibility genes is not easy due to the complexity of the disorder. Since lithium (Li) has been used for over 40 years now as an effective prophylactic agent and response to Li treatment seems to be, at least in part, genetically determined, classification according to Li response is a manner through which more homogeneous populations can be obtained for investigation. It has previously been suggested that Li exerts an effect on signal transduction pathways, such as the cyclic adenosine monophosphate (cAMP) pathway. We carried out an association study of BD with CREB1, CREB2 and CREB3 genes, located at ch 2q32.3-q34, 22q13.1 and 9pter-p22.1, respectively. A total of three promoter single nucleotide polymorphisms (SNP), 14 SNPs in the UTR, 6 exonic and 15 intronic SNPs were investigated for their frequency and haplotype distribution in a BD sample of 180 lithium responders and 69 nonresponders and 127 controls using a SNaPshot multiplex reaction from Applied Biosystems, a modified fluorescent single base pair extension procedure. Following correction for multiple testing, our results suggest that the CREB1-1H SNP (G/A change, P < 0.002) and the CREB1-7H SNP (T/C change, P < 0.002) may be associated with BD and/or lithium response.

Experiential and genetic contributions to depressive- and anxiety-like disorders: clinical and experimental studies

Stressful events have been implicated in the precipitation of depression and anxiety. These disorders may evolve owing to one or more of an array of neuronal changes that occur in several brain regions. It seems likely that these stressor-provoked neurochemical alterations are moderated by genetic determinants, as well as by a constellation of experiential and environmental factors. Indeed, animal studies have shown that vulnerability to depressive-like behaviors involve mechanisms similar to those associated with human depression (e.g., altered serotonin, corticotropin releasing hormone and their receptors, growth factors), and that the effects of stressors are influenced by previous stressor experiences, particularly those encountered early in life. These stressor effects might reflect sensitization of neuronal functioning, phenotypic changes of processes that lead to neurochemical release or receptor sensitivity, or epigenetic processes that modify expression of specific genes associated with stressor reactivity. It is suggested that depression is a life-long disorder, which even after effective treatment, has a high rate of re-occurrence owing to sensitized processes or epigenetic factors that promote persistent alterations of gene expression.

Linkage scan for quantitative traits identifies new regions of interest for substance dependence in the Collaborative Study on the Genetics of Alcoholism (COGA) sample

Dependence on alcohol and illicit drugs frequently co-occur. Results from a number of twin studies suggest that heritable influences on alcohol dependence and drug dependence may substantially overlap. Using large, genetically informative pedigrees from the Collaborative Study on the Genetics of Alcoholism (COGA), we performed quantitative linkage analyses using a panel of 1717 SNPs. Genome-wide linkage analyses were conducted for quantitative measures of DSM-IV alcohol dependence criteria, cannabis dependence criteria and dependence criteria across any illicit drug (including cannabis) individually and in combination as an average score across alcohol and illicit drug dependence criteria. For alcohol dependence, LOD scores exceeding 2.0 were noted on chromosome 1 (2.0 at 213 cM), 2 (3.4 at 234 cM) and 10 (3.7 at 60 cM). For cannabis dependence, a maximum LOD of 1.9 was noted at 95 cM on chromosome 14. For any illicit drug dependence, LODs of 2.0 and 2.4 were observed on chromosome 10 (116 cM) and 13 (64 cM) respectively. Finally, the combined alcohol and/or drug dependence symptoms yielded LODs >2.0 on chromosome 2 (3.2, 234 cM), 10 (2.4 and 2.6 at 60 cM and 116 cM) and 13 (2.1 at 64 cM). These regions may harbor genes that contribute to the biological basis of alcohol and drug dependence.

Stress, depression, and neuroplasticity: a convergence of mechanisms

Increasing evidence demonstrates that neuroplasticity, a fundamental mechanism of neuronal adaptation, is disrupted in mood disorders and in animal models of stress. Here we provide an overview of the evidence that chronic stress, which can precipitate or exacerbate depression, disrupts neuroplasticity, while antidepressant treatment produces opposing effects and can enhance neuroplasticity. We discuss neuroplasticity at different levels: structural plasticity (such as plastic changes in spine and dendrite morphology as well as adult neurogenesis), functional synaptic plasticity, and the molecular and cellular mechanisms accompanying such changes. Together, these studies elucidate mechanisms that may contribute to the pathophysiology of depression. Greater appreciation of the convergence of mechanisms between stress, depression, and neuroplasticity is likely to lead to the identification of novel targets for more efficacious treatments.

Association analysis of the chromosome 4p15-p16 candidate region for bipolar disorder and schizophrenia

Several independent linkage studies have identified chromosome 4p15-p16 as a putative region of susceptibility for bipolar disorder (BP), schizophrenia (SCZ) and related phenotypes. Previously, we identified two subregions (B and D) of the 4p15-p16 region that are shared by three of four 4p-linked families examined. Here, we describe a large-scale association analysis of regions B and D (3.8 and 4.5 Mb, respectively). We selected 408 haplotype-tagging single nucleotide polymorphisms (SNPs) on a block-by-block basis from the International HapMap project and tested them in 368 BP, 386 SCZ and 458 control individuals. Nominal significance thresholds were determined using principal component analysis as implemented in the program SNPSpD. In region B, overlapping SNPs and haplotypes met the region-wide threshold (P<or=0.0005) at the global and individual haplotype test level and clustered in two regions. In region D, no individual SNPs were nominally significant, but multiple global and individual haplotypes were associated with BP and/or SCZ (region-wide threshold, P<or=0.0003). These overlapping haplotypes fell into two regions. Within each of these four clusters, at least one globally significant haplotype withstood permutation testing (P(gp)<or=0.05). Five predicted genes were found within these associated regions, while Known/RefSeq genes, including KIAA0746 and PPARGC1A, mapped nearby. There were also nine other clusters within regions B and D with nominally significant haplotypes, but only at the individual haplotype level. KIAA0746, PPARGC1A, GPR125, CCKAR and DKFZp761B107 overlapped with these regions. This study has identified significant associations between BP and SCZ within the chromosome 4p linkage region, resulting in candidate regions worthy of further investigation.

Consensus paper of the WFSBP Task Force on Biological Markers: biological markers in depression

Biological markers for depression are of great interest to aid in elucidating the causes of major depression. We assess currently available biological markers to query their validity for aiding in the diagnosis of major depression. We specifically focus on neurotrophic factors, serotonergic markers, biochemical markers, immunological markers, neuroimaging, neurophysiological findings, and neuropsychological markers. We delineate the most robust biological markers of major depression. These include decreased platelet imipramine binding, decreased 5-HT1A receptor expression, increase of soluble interleukin-2 receptor and interleukin-6 in serum, decreased brain-derived neurotrophic factor in serum, hypocholesterolemia, low blood folate levels, and impaired suppression of the dexamethasone suppression test. To date, however, none of these markers are sufficiently specific to contribute to the diagnosis of major depression. Thus, with regard to new diagnostic manuals such as DSM-V and ICD-11 which are currently assessing whether biological markers may be included in diagnostic criteria, no biological markers for major depression are currently available for inclusion in the diagnostic criteria.

Clinical and genetic dissection of anger expression and CREB1 polymorphisms in major depressive disorder

BACKGROUND

Anger and irritability are prominent in a subset of individuals with major depressive disorder (MDD). Phosphorylation of the transcription factor cyclic adenosine monophosphate (cAMP) Response Element Binding Protein (CREB) has been associated with aggression or reward/aversion in rodents, and markers near CREB1 have been linked to MDD. Therefore, we examined the association between CREB1 polymorphisms and anger expression in MDD.

METHODS

A clinical sample of 94 Caucasian outpatients with MDD (42 male, 52 female) completed the Spielberger State-Trait Anger Expression Inventory. We examined six tagging single nucleotide polymorphisms (SNPs) spanning CREB1 and flanking regions for association with a summary measure of frequency and intensity of anger expression. We also introduced a novel statistical method to dissect the independent effect of individual SNPs and haplotypes.

RESULTS

For the sample as a whole, one of six SNPs tested was significantly associated with anger expression (empirical p = .003). Among the male subsample, this association was particularly marked (empirical p = 8 x 10(-5)). A global haplotype test of the six SNPs was likewise significant (p = 3.7 x 10(-6)). No single SNP or haplotype accounted for all of the association observed.

CONCLUSION

These preliminary results suggest a strong, gender-specific association between variation at the CREB1 locus and anger expression in MDD.