Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The P2RX7 gene is located within a region on chromosome 12q24.31 that has been identified as a susceptibility locus for affective disorders by linkage and association studies. P2RX7 is a purinergic ATP-binding calcium channel expressed in neurons as well as in microglial cells in various brain regions. We investigated 29 single nucleotide polymorphisms (SNPs) within the P2RX7 gene and adjacent genes in a sample of 1000 German Caucasian patients suffering from recurrent major depressive disorder (MDD). These were contrasted with diagnosed healthy Caucasian controls from the same population (n=1029). A non-synonymous coding SNP in the P2RX7 gene (rs2230912), previously found to be associated with bipolar disorder, was significantly associated (P=0.0019) with MDD. This polymorphism results in an amino acid exchange in the C-terminal cytosolic domain of the P2RX7 channel protein, suggesting that the observed P2RX7 polymorphism might play a causal role in the development of depression.
Hum Mol Genet 2006 Aug 15
PMID:P2RX7, a gene coding for a purinergic ligand-gated ion channel, is associated with major depressive disorder. 1682 51

Angiotensin-converting enzyme (ACE) is assumed to influence the activity of the hypothalamic-pituitary-adrenocortical (HPA) system, which shows hyperactivity in the majority of patients with major depression. The ACE gene, known to be associated with cardiovascular disorders, which in turn are accompanied with an increased susceptibility for depression, is therefore a promising candidate gene for affective disorders. We investigated the genetic association between 35 single-nucleotide polymorphisms (SNPs) and an insertion/deletion (I/D)-polymorphism in the ACE gene and the susceptibility for unipolar major depression together with the genetic association with ACE serum activity and functional parameters of the HPA system. Two independent case/control samples with a total of 843 unrelated unipolar depressed patients and 1479 healthy controls were investigated. A case/control sample was screened to detect genetic associations with unipolar major depression. In addition, a replication sample was used to confirm the detected associations and to further investigate functional consequences of the genetic variants associated with depression. In the screening sample, two SNPs within the ACE gene were significantly associated with unipolar major depression. The association with unipolar major depression of one SNP (rs4291) located in the promoter region of the ACE gene was confirmed in our replication sample. The T-allele of this SNP was associated with depression and depressed T-allele carriers showed higher ACE serum activity and HPA-axis hyperactivity. Variants of the ACE gene such as SNP rs4291 are suggested susceptibility factors for unipolar major depression. We could show that SNP rs4291 influences ACE activity and HPA-axis hyperactivity and might therefore represent a common pathophysiologic link for unipolar depression and cardiovascular disease.
Mol Psychiatry 2006 Nov
PMID:Polymorphisms in the angiotensin-converting enzyme gene are associated with unipolar depression, ACE activity and hypercortisolism. 1692 68

Disrupted-in-schizophrenia 1 (DISC1), identified in a pedigree with a familial psychosis with the chromosome translocation (1:11), is a putative susceptibility gene for psychoses such as schizophrenia and bipolar disorder. Although there are a number of patients with major depressive disorder (MDD) in the family members with the chromosome translocation, the possible association with MDD has not yet been studied. We therefore performed an association study of the DISC1 gene with MDD and schizophrenia. We found that Cys704 allele of the Ser704Cys single-nucleotide polymorphism (SNP) was associated with an increased risk of developing MDD (P=0.005, odds ratio=1.46) and stronger evidence for association in a multi-marker haplotype analysis containing this SNP (P=0.002). We also explored possible impact of Ser704Cys on brain morphology in healthy volunteers using MR imaging. We found a reduction in gray matter volume in cingulate cortex and a decreased fractional anisotropy in prefrontal white matter of individuals carrying the Cys704 allele compared with Ser/Ser704 subjects. In primary neuronal culture, knockdown of endogenous DISC1 protein by small interfering RNA resulted in the suppression of phosphorylation of ERK and Akt, whose signaling pathways are implicated in MDD. When effects of sDISC1 (Ser704) and cDISC1 (Cys704) proteins were examined separately, phosphorylation of ERK was greater in sDISC1 compared with cDISC1. A possible biological mechanism of MDD might be implicated by these convergent data that Cys704 DISC1 is associated with the lower biological activity on ERK signaling, reduced brain gray matter volume and an increased risk for MDD.
Hum Mol Genet 2006 Oct 15
PMID:Impact of the DISC1 Ser704Cys polymorphism on risk for major depression, brain morphology and ERK signaling. 1695 94

The prefrontal cortex, a part of the limbic-thalamic-cortical network, participates in regulation of mood, cognition and behavior and has been implicated in the pathophysiology of major depressive disorder (MDD). Many neuropsychological studies demonstrate impairment of working memory in patients with MDD. However, there are few functional neuroimaging studies of MDD patients during working memory processing, and most of the available ones included medicated patients or patients with both MDD and bipolar disorder. We used functional magnetic resonance imaging (fMRI) to measure prefrontal cortex function during working memory processing in untreated depressed patients with MDD. Fifteen untreated individuals with Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition recurrent MDD (mean age+/-s.d.=34.3+/-11.5 years) and 15 healthy comparison subjects (37.7+/-12.1 years) matched for age, sex and race were studied using a GE/Elscint 2T MR system. An echo-planar MRI sequence was used to acquire 24 axial slices. The n-back task (0-back, 1-back and 2-back) was used to elicit frontal cortex activation. Data were analyzed with a multiple regression analysis using the FSL-FEAT software. MDD patients showed significantly greater left dorsolateral cortex activation during the n-back task compared to the healthy controls (P<0.01), although task performance was similar in the two groups. Furthermore, the patients showed significant anterior cingulate cortex activation during the task, but the comparison subjects did not (P<0.01). This study provides in vivo imaging evidence of abnormal frontolimbic circuit function during working memory processing in individuals with MDD.
Mol Psychiatry 2007 Feb
PMID:Prefrontal hyperactivation during working memory task in untreated individuals with major depressive disorder. 1698 90

The limbic system has consistently been associated with the control of emotions and with mood disorders. The goal of this study was to identify new molecular targets associated with suicide and with major depression using oligonucleotide microarrays in the limbic system (amygdala, hippocampus, anterior cingulate gryus (BA24) and posterior cingulate gyrus (BA29)). A total of 39 subjects were included in this study. They were all male subjects and comprised 26 suicides (depressed suicides=18, non depressed suicides=8) and 13 matched controls. Brain gene expression analysis was carried out on human brain samples using the Affymetrix HG U133 chip set. Differential expression in each of the limbic regions showed group-specific patterns of expression, supporting particular neurobiological mechanisms implicated in suicide and depression. Confirmation of genes selected based on their significance and the interest of their function with reverse transcriptase-polymerase chain reaction showed consistently correlated signals with the results obtained in the microarray analysis. Gene ontology analysis with differentially expressed genes revealed an overrepresentation of transcription and metabolism-related genes in the hippocampus and amygdala, whereas differentially expressed genes in BA24 and BA29 were more generally related to RNA-binding, regulation of enzymatic activity and protein metabolism. Limbic expression patterns were most extensively altered in the hippocampus, where processes related to major depression were associated with altered expression of factors involved with transcription and cellular metabolism. Additionally, our results confirm previous evidence pointing to global alteration of gabaergic neurotransmission in suicide and major depression, offering new avenues in the study and possibly treatment of such complex disorders. Overall, these data suggest that specific patterns of expression in the limbic system contribute to the etiology of depression and suicidal behaviors and highlight the role of the hippocampus in major depression.
Mol Psychiatry 2007 Jul
PMID:Patterns of gene expression in the limbic system of suicides with and without major depression. 1735 12

Dysfunction in the monoamine systems of serotonin (5-HT), norepinephrine (NE) and dopamine (DA) may causally be related to major depressive disorder (MDD). Monoamine depletion studies investigate the direct effects of monoamines on mood. Acute tryptophan depletion (ATD) or para-chlorophenylalanine (PCPA) deplete 5-HT, acute phenylalanine/tyrosine depletion (APTD) or alpha-methyl-para-tyrosine (AMPT) deplete NE/DA. Available depletion studies found conflicting results in heterogeneous populations: healthy controls, patients with previous MDD in remission and patients suffering from MDD. The decrease in mood after 5-HT and NE/DA depletion in humans is reviewed and quantified. Systematic search of MEDLINE and EMBASE (1966-October 2006) and cross-references was carried out. Randomized studies applying ATD, PCPA, APTD or AMPT vs control depletion were included. Pooling of results by meta-analyses was stratified for studied population and design of the study (within or between subjects). Seventy-three ATD, 2 PCPA, 10 APTD and 8 AMPT studies were identified of which 45 ATD and 8 APTD studies could be meta-analyzed. 5-HT or NE/DA depletion did not decrease mood in healthy controls. 5-HT or NE/DA depletion slightly lowered mood in healthy controls with a family history of MDD. In drug-free patients with MDD in remission, a moderate mood decrease was found for ATD, without an effect of APTD. ATD induced relapse in patients with MDD in remission who used serotonergic antidepressants. In conclusion, monoamine depletion studies demonstrate decreased mood in subjects with a family history of MDD and in drug-free patients with MDD in remission, but do not decrease mood in healthy humans. Although depletion studies usefully investigate the etiological link of 5-HT and NE with MDD, they fail to demonstrate a causal relation. They presumably clarify a vulnerability trait to become depressed. Directions for further investigation of this vulnerability trait are proposed.
Mol Psychiatry 2007 Apr
PMID:Mood is indirectly related to serotonin, norepinephrine and dopamine levels in humans: a meta-analysis of monoamine depletion studies. 1738 2

Major depressive disorder (MDD) is a common and highly heterogeneous psychiatric disorder encompassing a spectrum of symptoms involving deficits to a range of cognitive, psychomotor and emotional processes. As is the norm for aetiological studies into the majority of psychiatric phenotypes, particular focus has fallen on the interplay between genetic and environmental factors. There are, however, several epidemiological, clinical and molecular peculiarities associated with MDD that are hard to explain using traditional gene- and environment-based approaches. Our goal in this study is to demonstrate the benefits of looking beyond conventional 'DNA+environment' and 'DNA x environment' aetiological paradigms. Epigenetic factors - inherited and acquired modifications of DNA and histones that regulate various genomic functions occurring without a change in nuclear DNA sequence - offer new insights about many of the non-Mendelian features of major depression, and provide a direct mechanistic route via which the environment can interact with the genome. The study of epigenetics, especially in complex diseases, is a relatively new field of research, and optimal laboratory techniques and analysis methods are still being developed. Incorporating epigenetic research into aetiological studies of MDD thus presents a number of methodological and interpretive challenges that need to be addressed. Despite these difficulties, the study of DNA methylation and histone modifications has the potential to transform our understanding about the molecular aetiology of complex diseases.
Mol Psychiatry 2007 Sep
PMID:Molecular studies of major depressive disorder: the epigenetic perspective. 1742 Jul 65

Highly prevalent stress-related disorders such as major depression (MD) are characterised by a dysregulation of the neuroendocrine system. Although heritability for these disorders is high, the role of genes in the underlying pathophysiology is poorly understood. Here, we show that polymorphic variations in genes coding for serotonin transporter (5-HTT), catechol-O-methyl transferase (COMT) and monoamine oxidase A (MAOA) as well as sex differences influence the regulation of hypothalamic-pituitary-adrenal (HPA)-axis response to acute psychological and endocrine challenges. In our sample, the effects of COMT on the release of adrenocorticotrophin hormone (ACTH) depend on the presence of the low-expression MAOA variant in the same individual. By including individuals varying in their degree of susceptibility to MD, we showed evidence of interactions between 5-HTT and MD susceptibility in baseline cortisol, and between MAOA and MD susceptibility in baseline ACTH measures, indicating a role for these genotypes in stable-state endocrine regulation. Collectively, these results indicate that the simultaneous investigation of multiple monoaminergic genes in interaction with gender have to be measured to understand the endocrine regulation of stress. These findings point towards a genetic susceptibility to stress-related disorders.
Mol Psychiatry 2007 May
PMID:Convergent genetic modulation of the endocrine stress response involves polymorphic variations of 5-HTT, COMT and MAOA. 1745 62

Tryptophan hydroxylase isoform 2 (TPH2) is expressed in serotonergic neurons in the raphe nuclei, where it catalyzes the rate-limiting step in the synthesis of the neurotransmitter serotonin. In search for functional polymorphisms within the TPH2 gene locus, we measured allele-specific expression of TPH2 mRNA in sections of human pons containing the dorsal and median raphe nuclei. Differences in allelic mRNA expression--referred to as allelic expression imbalance (AEI)--are a measure of cis-acting regulation of gene expression and mRNA processing. Two marker SNPs, located in exons 7 and 9 of TPH2 (rs7305115 and rs4290270, respectively), served for quantitative allelic mRNA measurements in pons RNA samples from 27 individuals heterozygous for one or both SNPs. Significant AEI (ranging from 1.2- to 2.5-fold) was detected in 19 out of the 27 samples, implying the presence of cis-acting polymorphisms that differentially affect TPH2 mRNA levels in pons. For individuals heterozygous for both marker SNPs, the results correlated well (r=0.93), validating the AEI analysis. AEI is tightly associated with the exon 7 marker SNP, in 17 of 18 subjects. Remarkably, expression from the minor allele exceeded that of the major allele in each case, possibly representing a gain-of-function. Genotyping of 20 additional TPH2 SNPs identified a haplotype block of five tightly linked SNPs for which heterozygosity is highly correlated with AEI and overall expression of TPH2 mRNA. These results reveal the presence of a functional cis-acting polymorphism, with high frequency in normal human subjects, resulting in increased TPH2 expression levels. The SNPs that correlate with AEI are closely linked to TPH2 SNPs previously shown to associate with major depression and suicide.
Mol Psychiatry 2007 May
PMID:Tryptophan hydroxylase 2 (TPH2) haplotypes predict levels of TPH2 mRNA expression in human pons. 1745 63

Beside the well-known deficiency in serotonergic neurotransmission as pathophysiological correlate of major depression (MD), recent evidence points to a pivotal role of increased glutamate receptor activation as well. However, cause and interaction of these neurotransmitter alterations are not understood. In this review, we present a hypothesis integrating current concepts of neurotransmission and hypothalamus-pituitary-adrenal (HPA) axis dysregulation with findings on immunological alterations and alterations in brain morphology in MD. An immune activation including increased production of proinflammatory cytokines has repeatedly been described in MD. Proinflammatory cytokines such as interleukin-2, interferon-gamma, or tumor necrosis factor-alpha activate the tryptophan- and serotonin-degrading enzyme indoleamine 2,3-dioxygenase (IDO). Depressive states during inflammatory somatic disorders are also associated with increased proinflammatory cytokines and increased consumption of tryptophan via activation of IDO. An enhanced consumption of serotonin and its precursor tryptophan through IDO activation could well explain the reduced availability of serotonergic neurotransmission in MD. An increased activation of IDO and its subsequent enzyme kynurenine monooxygenase by proinflammatory cytokines, moreover, leads to an enhanced production of quinolinic acid, a strong agonist of the glutamatergic N-methyl-D-aspartate receptor. In inflammatory states of the central nervous system, IDO is mainly activated in microglial cells, which preferentially metabolize tryptophan to the NMDA receptor agonist quinolinic acid, whereas astrocytes - counteracting this metabolism due to the lack of an enzyme of this metabolism - have been observed to be reduced in MD. Therefore the type 1/type 2 immune response imbalance, associated with an astrocyte/microglia imbalance, leads to serotonergic deficiency and glutamatergic overproduction. Astrocytes are further strongly involved in re-uptake and metabolic conversion of glutamate. The reduced number of astrocytes could contribute to both, a diminished counterregulation of IDO activity in microglia and an altered glutamatergic neurotransmission. Further search for antidepressant agents should take into account anti-inflammatory drugs, for example, cyclooxygenase-2 inhibitors, might exert antidepressant effects by acting on serotonergic deficiency, glutamatergic hyperfunction and antagonizing neurotoxic effects of quinolinic acid.
Mol Psychiatry 2007 Nov
PMID:The immune-mediated alteration of serotonin and glutamate: towards an integrated view of depression. 1745 12


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