| 1 | Psychopharmacology (Berl.) 2005 Dec 183: 378-82 |
|---|---|
| PMID | 16240163 |
| Title | Tryptophan hydroxylase 2 gene expression and promoter polymorphisms in bipolar disorder and schizophrenia. |
| Abstract | The tryptophan hydroxylase isoform-2 gene (TPH2) is located on chromosome 12 and is expressed primarily in brain tissue. Although the tryptophan hydroxylase isoform-1 gene (Tph1) has been reported to have a genetic association with bipolar disorder and schizophrenia, the Tph1 isoform is expressed at much lower levels than TPH2 (150-fold less in the mouse brain). We hypothesized that bipolar disorder and schizophrenia are associated with abnormal levels of TPH2 mRNA in the brain. TPH2 and beta-actin mRNA levels in postmortem brain were quantified using real-time PCR. mRNA samples provided by the Stanley Foundation Array Collection were derived from the dorsolateral prefrontal cortex (Brodmann Area 46) of 35 bipolar, 35 schizophrenic, and 35 control subjects. There were significant differences in the mRNA levels among bipolar, schizophrenic, and normal subjects [F(2,102)=3.58; p=0.031]. A greater amount of TPH2 mRNA was found in the bipolar group in comparison with control subjects (Tukey's test: p=0.024). Further investigations of TPH2 are needed to clarify the potential role of this gene in the pathophysiology of bipolar disorder. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 2 | Psychopharmacology (Berl.) 2005 Dec 183: 378-82 |
| PMID | 16240163 |
| Title | Tryptophan hydroxylase 2 gene expression and promoter polymorphisms in bipolar disorder and schizophrenia. |
| Abstract | The tryptophan hydroxylase isoform-2 gene (TPH2) is located on chromosome 12 and is expressed primarily in brain tissue. Although the tryptophan hydroxylase isoform-1 gene (Tph1) has been reported to have a genetic association with bipolar disorder and schizophrenia, the Tph1 isoform is expressed at much lower levels than TPH2 (150-fold less in the mouse brain). We hypothesized that bipolar disorder and schizophrenia are associated with abnormal levels of TPH2 mRNA in the brain. TPH2 and beta-actin mRNA levels in postmortem brain were quantified using real-time PCR. mRNA samples provided by the Stanley Foundation Array Collection were derived from the dorsolateral prefrontal cortex (Brodmann Area 46) of 35 bipolar, 35 schizophrenic, and 35 control subjects. There were significant differences in the mRNA levels among bipolar, schizophrenic, and normal subjects [F(2,102)=3.58; p=0.031]. A greater amount of TPH2 mRNA was found in the bipolar group in comparison with control subjects (Tukey's test: p=0.024). Further investigations of TPH2 are needed to clarify the potential role of this gene in the pathophysiology of bipolar disorder. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 3 | Psychiatry Res 2005 Apr 134: 195-8 |
| PMID | 15840421 |
| Title | Promoter polymorphism of second tryptophan hydroxylase isoform (TPH2) in schizophrenia and suicidality. |
| Abstract | Allele and haplotype frequencies of a promoter polymorphism in the gene encoding tryptophan hydroxylase (TPH2) did not differ in 83 suicidal schizophrenic patients compared with 170 non-suicidal schizophrenic patients. These findings suggest that these 5' marker haplotypes in the TPH2 gene do not influence suicidal behavior in schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 4 | Psychiatry Res 2005 Apr 134: 195-8 |
| PMID | 15840421 |
| Title | Promoter polymorphism of second tryptophan hydroxylase isoform (TPH2) in schizophrenia and suicidality. |
| Abstract | Allele and haplotype frequencies of a promoter polymorphism in the gene encoding tryptophan hydroxylase (TPH2) did not differ in 83 suicidal schizophrenic patients compared with 170 non-suicidal schizophrenic patients. These findings suggest that these 5' marker haplotypes in the TPH2 gene do not influence suicidal behavior in schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 5 | J. Mol. Neurosci. 2005 -1 26: 33-7 |
| PMID | 15968084 |
| Title | Postmortem parietal cortex TPH2 expression is not altered in schizophrenic, unipolar-depressed, and bipolar patients vs control subjects. |
| Abstract | Serotonin (5-hydroxytryptamine [5-HT]) is a neurotransmitter synthesized in the raphe nuclei of the brain stem in the central nervous system (CNS) and also in the periphery. Dysfunction of the serotonergic system has been implicated in the pathogenesis of psychiatric disorders. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in 5-HT biosynthesis. For more than a decade, only one gene encoding TPH was identified in vertebrates. Recently, a second TPH gene, designated TPH2, was detected, located on human chromosome 12, a susceptibility region for affective disorders. TPH2 is predominantly expressed in the brain, whereas the classical TPH gene, TPH1, is expressed in peripheral tissues. The discovery of the brain-abundant TPH2 gene justifies a new concept of the CNS serotonergic system. TPH2, rather than TPH1, has now become a candidate gene for 5-HT-related affective disorders. We compared TPH2 mRNA levels in postmortem parietal cortex of unipolar-depressed, bipolar, and schizophrenic patients vs control subjects, using real-time reverse transcription polymerase chain reaction. No significant difference in TPH2 mRNA levels was found among the four diagnostic groups. The lack of difference might suggest that this gene is not involved in the etiology of of these psychiatric disorders. Alternatively, it is possible that the parietal cortex is not the relevant brain area involved in the pathophysiology of these disorders or that posttranscriptional modifications of TPH2 mRNA occur in these patients, causing changes in protein levels and/or enzymatic activity. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 6 | Genes Brain Behav. 2006 Feb 5: 107-10 |
| PMID | 16436194 |
| Title | The interaction between TPH2 promoter haplotypes and clinical-demographic risk factors in suicide victims with major psychoses. |
| Abstract | Tryptophan hydroxylase isoform 2 (TPH2) is a rate-limiting enzyme in the biosynthesis of serotonin (5-HT) and is predominantly localized in the brain. Previous studies have suggested that there is an association between serotonergic dysfunction in the brain and suicidality. This study was designed to examine whether the -473T > A and -8396G > C polymorphisms of the TPH2 gene may be associated with completed suicide in subjects with major psychoses from the Stanley Foundation Brain Bank sample. TPH2 genotypes were determined in 69 subjects with a diagnosis of schizophrenia or bipolar disorder, among which 22 died by suicide. Genomic DNA was amplified by polymerase chain reaction and typed by automated methods. Both markers were found to be in Hardy-Weinberg equilibrium and in strong linkage disequilibrium. No association with history of suicide was found for either polymorphism. Haplotype analysis with EHAP showed no association between completed suicide and haplotype distribution (chi2 = 1.877; 3 df; P = 0.598). Nor was there any association between suicide and these genetic markers even when clinical-demographic factors were considered as covariates in the haplotype analysis. These findings suggest that these 5' marker haplotypes in the TPH2 gene do not influence suicidal behaviour. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 7 | Psychiatry Clin. Neurosci. 2007 Feb 61: 3-19 |
| PMID | 17239033 |
| Title | Molecular genetics of bipolar disorder and depression. |
| Abstract | In this review, all papers relevant to the molecular genetics of bipolar disorder published from 2004 to the present (mid 2006) are reviewed, and major results on depression are summarized. Several candidate genes for schizophrenia may also be associated with bipolar disorder: G72, DISC1, NRG1, RGS4, NCAM1, DAO, GRM3, GRM4, GRIN2B, MLC1, SYNGR1, and SLC12A6. Of these, association with G72 may be most robust. However, G72 haplotypes and polymorphisms associated with bipolar disorder are not consistent with each other. The positional candidate approach showed an association between bipolar disorder and TRPM2 (21q22.3), GPR50 (Xq28), Citron (12q24), CHMP1.5 (18p11.2), GCHI (14q22-24), MLC1 (22q13), GABRA5 (15q11-q13), BCR (22q11), CUX2, FLJ32356 (12q23-q24), and NAPG (18p11). Studies that focused on mood disorder comorbid with somatic symptoms, suggested roles for the mitochondrial DNA (mtDNA) 3644 mutation and the POLG mutation. From gene expression analysis, PDLIM5, somatostatin, and the mtDNA 3243 mutation were found to be related to bipolar disorder. Whereas most previous positive findings were not supported by subsequent studies, DRD1 and IMPA2 have been implicated in follow-up studies. Several candidate genes in the circadian rhythm pathway, BmaL1, TIMELESS, and PERIOD3, are reported to be associated with bipolar disorder. Linkage studies show many new linkage loci. In depression, the previously reported positive finding of a gene-environmental interaction between HTTLPR (insertion/deletion polymorphism in the promoter of a serotonin transporter) and stress was not replicated. Although the role of the TPH2 mutation in depression had drawn attention previously, this has not been replicated either. Pharmacogenetic studies show a relationship between antidepressant response and HTR2A or FKBP5. New technologies for comprehensive genomic analysis have already been applied. HTTLPR and BDNF promoter polymorphisms are now found to be more complex than previously thought, and previous papers on these polymorphisms should be treated with caution. Finally, this report addresses some possible causes for the lack of replication in this field. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 8 | Hum. Mutat. 2008 Jul 29: 891-902 |
| PMID | 18444257 |
| Title | Mutations in human monoamine-related neurotransmitter pathway genes. |
| Abstract | Biosynthesis and metabolism of serotonin and catecholamines involve at least eight individual enzymes that are mainly expressed in tissues derived from the neuroectoderm, e.g., the central nervous system (CNS), pineal gland, adrenal medulla, enterochromaffin tissue, sympathetic nerves, and ganglia. Some of the enzymes appear to have additional biological functions and are also expressed in the heart and various other internal organs. The biosynthetic enzymes are tyrosine hydroxylase (TH), tryptophan hydroxylases type 1 and 2 (TPH1, TPH2), aromatic amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DbetaH), and phenylethanolamine N-methyltransferase (PNMT), and the specific catabolic enzymes are monoamine oxidase A (MAO-A) and catechol O-methyltransferase (COMT). For the TH, DDC, DBH, and MAOA genes, many single nucleotide polymorphisms (SNPs) with unknown function, and small but increasing numbers of cases with autosomal recessive mutations have been recognized. For the remaining genes (TPH1, TPH2, PNMT, and COMT) several different genetic markers have been suggested to be associated with regulation of mood, pain perception, and aggression, as well as psychiatric disturbances such as schizophrenia, depression, suicidality, and attention deficit/hyperactivity disorder. The genetic markers may either have a functional role of their own, or be closely linked to other unknown functional variants. In the future, molecular testing may become important for the diagnosis of such conditions. Here we present an overview on mutations and polymorphisms in the group of genes encoding monoamine neurotransmitter metabolizing enzymes. At the same time we propose a unified nomenclature for the nucleic acid aberrations in these genes. New variations or details on mutations will be updated in the Pediatric Neurotransmitter Disorder Data Base (PNDDB) database (www.bioPKU.org). |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 9 | Proc. Natl. Acad. Sci. U.S.A. 2008 Jan 105: 1333-8 |
| PMID | 18212115 |
| Title | Role of GSK3 beta in behavioral abnormalities induced by serotonin deficiency. |
| Abstract | Dysregulation of brain serotonin (5-HT) neurotransmission is thought to underlie mental conditions as diverse as depression, anxiety disorders, bipolar disorder, autism, and schizophrenia. Despite treatment of these conditions with serotonergic drugs, the molecular mechanisms by which 5-HT is involved in the regulation of aberrant emotional behaviors are poorly understood. Here, we generated knockin mice expressing a mutant form of the brain 5-HT synthesis enzyme, tryptophan hydroxylase 2 (TPH2). This mutant is equivalent to a rare human variant (R441H) identified in few individuals with unipolar major depression. Expression of mutant TPH2 in mice results in markedly reduced ( approximately 80%) brain 5-HT production and leads to behavioral abnormalities in tests assessing 5-HT-mediated emotional states. This reduction in brain 5-HT levels is accompanied by activation of glycogen synthase kinase 3beta (GSK3beta), a signaling molecule modulated by many psychiatric therapeutic agents. Importantly, inactivation of GSK3beta in TPH2 knockin mice, using pharmacological or genetic approaches, alleviates the aberrant behaviors produced by 5-HT deficiency. These findings establish a critical role of TPH2 in the maintenance of brain serotonin homeostasis and identify GSK3beta signaling as an important pathway through which brain 5-HT deficiency induces abnormal behaviors. Targeting GSK3beta and related signaling events may afford therapeutic advantages for the management of certain 5-HT-related psychiatric conditions. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 10 | Neuroscience 2009 Nov 164: 331-43 |
| PMID | 19358880 |
| Title | The genetics of bipolar disorder. |
| Abstract | Bipolar disorder is a mood disorder characterized by impairing episodes of mania and depression. Twin studies have established that bipolar disorder is among the most heritable of medical disorders and efforts to identify specific susceptibility genes have intensified over the past two decades. The search for genes influencing bipolar disorder has been complicated by a paucity of animal models, limited understanding of pathogenesis, and the genetic and phenotypic complexity of the syndrome. Linkage studies have implicated several chromosomal regions as harboring relevant genes, but results have been inconsistent. It is now widely accepted that the genetic liability to bipolar disorder reflects the action of many genes of individually small effect, a scenario for which linkage studies are poorly suited. Thus, association studies, which are more powerful for the detection of modest effect loci, have become the focus of gene-finding research. A large number of candidate genes, including biological candidates derived from hypotheses about the pathogenesis of the disorder and positional candidates derived from linkage and cytogenetic studies, have been evaluated. Several of these genes have been associated with the disorder in independent studies (including BDNF, DAOA, DISC1, GRIK4, SLC6A4, and TPH2), but none has been established. The clinical heterogeneity of bipolar disorder and its phenotypic and genetic overlap with other disorders (especially schizophrenia, schizoaffective disorder, and major depressive disorder) have raised questions about the optimal phenotype definition for genetic studies. Nevertheless, genomewide association analysis, which has successfully identified susceptibility genes for a variety of complex disorders, has begun to implicate specific genes for bipolar disorder (DGKH, CACNA1C, ANK3). The polygenicity of the disorder means that very large samples will be needed to detect the modest effect loci that likely contribute to bipolar disorder. Detailed genetic dissection of the disorder may provide novel targets (both pharmacologic and psychosocial) for intervention. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 11 | Neuroscience 2009 Apr 159: 1274-82 |
| PMID | 19233335 |
| Title | Predominant expression of tryptophan hydroxylase 1 mRNA in the pituitary: a postmortem study in human brain. |
| Abstract | Although the predominant role of tryptophan hydroxylase 2 (TPH2) in the CNS and its influence on the vulnerability to psychiatric disorders have clearly been demonstrated in several studies, the role of TPH1 on neuronal mechanisms, respectively on behavioral traits is still poorly understood. In a previous study of tryptophan hydroxylase 1 (TPH1) and TPH2 mRNA expression in different human brain regions we observed significantly higher TPH1 than TPH2 mRNA concentrations in the pituitary (unpublished observations). Considering the importance of the pituitary in the functional circuits between brain and body, we investigated the TPH1 and TPH2 mRNA expression in more detail, using human postmortem samples of the posterior and anterior pituitary compared to cortex, hippocampus and raphe nuclei. Specimens were available from different psychiatric patients (drug abusers, n=12; suicide victims, n=11; schizophrenics, n=9) and controls (n=15). Additionally we performed immunohistochemical analysis applying monospecific antibodies for both TPH isoforms to verify that the mRNA is of cellular and not just vascular or other origin. Highest TPH2 mRNA levels were observed in the raphe nuclei in patients and controls. By contrast, in the anterior and posterior pituitary TPH1 was found to be the predominantly expressed isoform in all subgroups. TPH1 and TPH2 mRNA expression in the further brain regions was only marginal and nearly identical except in the hypothalamus where higher TPH1 than TPH2 mRNA levels could be measured. Interindividual differences between the subgroups were not detectable. The results of the present study extended our previous findings by the additional immunohistochemical determination of the neuronal TPH1 and TPH2 protein expression in the anterior pituitary and provide evidence against a strictly separated duality of the serotonergic system. It seems that TPH1 might also have an impact on neuronal mechanisms via hypothalamic-pituitary-adrenal axis regulation by its predominant localization in the pituitary. These observations may open up new research strategies not only for several psychiatric disorders, but also for the relationship between psychiatric and somatic diseases. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 12 | Genet. Mol. Res. 2010 -1 9: 1274-8 |
| PMID | 20623453 |
| Title | Linkage of schizophrenia with TPH2 and 5-HTR2A gene polymorphisms in the Malay population. |
| Abstract | The serotoninergic system has been implicated in the etiology of schizophrenia and other behavioral disorders. Association studies have focused on the tryptophan hydroxylase 2 gene (TPH2) and the 5-hydroxytryptamine receptor 2A gene (5-HTR2A). We genotyped two single-nucleotide polymorphisms, A1438G of 5-HTR2A and intronic rs1386494 of TPH2 in the Malay population, using a sample size of 289 schizophrenic patients and 130 healthy controls. We found a significant association of A1438G of 5-HTR2A with schizophrenia in Malays. On the other hand, TPH2 polymorphism was not associated with schizophrenia. This is the first genetic association study concerning schizophrenia in the Malay population. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 13 | Genet. Mol. Res. 2010 -1 9: 1274-8 |
| PMID | 20623453 |
| Title | Linkage of schizophrenia with TPH2 and 5-HTR2A gene polymorphisms in the Malay population. |
| Abstract | The serotoninergic system has been implicated in the etiology of schizophrenia and other behavioral disorders. Association studies have focused on the tryptophan hydroxylase 2 gene (TPH2) and the 5-hydroxytryptamine receptor 2A gene (5-HTR2A). We genotyped two single-nucleotide polymorphisms, A1438G of 5-HTR2A and intronic rs1386494 of TPH2 in the Malay population, using a sample size of 289 schizophrenic patients and 130 healthy controls. We found a significant association of A1438G of 5-HTR2A with schizophrenia in Malays. On the other hand, TPH2 polymorphism was not associated with schizophrenia. This is the first genetic association study concerning schizophrenia in the Malay population. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 14 | Expert Opin. Ther. Targets 2010 Nov 14: 1259-71 |
| PMID | 20874521 |
| Title | Targeting tryptophan hydroxylase 2 in affective disorder. |
| Abstract | Serotonin (5-HT) has been implicated in several psychiatric disorders including schizophrenia, depressive disorder and suicide. The key and rate limiting enzyme of 5-HT synthesis is tryptophan hydroxylase 2 (TPH2). The association between TPH2 and affective disorders as well as future vistas of its potential clinical targeting: i) TPH2 in the regulation of 5-HT-dependent behavior, ii) TPH2 gene polymorphism and human behavior, iii) TPH2 and sensitivity to antidepressants and iv) effect of dietary tryptophan manipulation on affective behavior are described. The main conclusions of the review are: i) there is an association between TPH2 and genetically defined behavioral variations, ii) the haplotypes, including some human TPH2 gene SNPs, can predict the risk of affective disorders and the sensitivity to antidepressant therapeutics, iii) mutations decreasing TPH2 activity produce negative effects on behavior and, possibly, on survival, iv) the effect of dietary tryptophan manipulations on human mood and behavior is modest compared with that of inhibitors of 5-HT transporter and monoamine oxidase. More comprehensive study of TPH2 genetics is needed to increase the clinical value of the enzyme as a predictor of affective disorder risk and efficacy of antidepressant drugs. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 15 | Neurosci. Lett. 2010 Mar 472: 194-8 |
| PMID | 20144688 |
| Title | Common genetic variations in TPH1/TPH2 genes are not associated with schizophrenia in Japanese population. |
| Abstract | Alteration of serotonin transmission in the brain of patients with schizophrenia has been reported in postmortem brain studies, cerebrospinal fluid studies, and pharmacological challenges. Although a genetic association of tryptophan hydroxylase isoform 1 (TPH1), the rate-limiting enzyme in serotonin synthesis, with schizophrenia has been suggested by recent systematic meta-analyses, the newly identified neuronal isoform TPH2 is more relevant to the central nervous system and the association of TPH2 gene with schizophrenia has been much less explored. We, therefore, explored the association of TPH2 gene with schizophrenia using a case-control study of 720 Japanese populations and also tried to replicate the association of the TPH1 rs1800532 (A218C) single nucleotide polymorphism (SNP) with schizophrenia. We selected 15 tagging SNPs in the TPH2 gene. We found no significant differences in genotypic distributions (uncorrected P=0.18-0.98) or allelic frequencies (uncorrected P=0.18-0.98) of the 15 SNPs between the schizophrenia and control groups. Haplotypes constructed with these SNPs were also not associated with schizophrenia (uncorrected P=0.12-0.97). The genotypic and allelic distribution of the TPH1 rs1800532 SNP was also not different between the case and control groups in our samples. In addition, a subsequent meta-analysis including our results did not showed a significant association with schizophrenia in Asian populations. Our findings suggest that neither common genetic variations of TPH1 nor TPH2 are likely to contribute to the genetic susceptibility to schizophrenia in Japanese population. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 16 | PLoS ONE 2010 -1 5: e8956 |
| PMID | 20126463 |
| Title | Alternative splicing and extensive RNA editing of human TPH2 transcripts. |
| Abstract | Brain serotonin (5-HT) neurotransmission plays a key role in the regulation of mood and has been implicated in a variety of neuropsychiatric conditions. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the biosynthesis of 5-HT. Recently, we discovered a second TPH isoform (TPH2) in vertebrates, including man, which is predominantly expressed in brain, while the previously known TPH isoform (TPH1) is primarly a non-neuronal enzyme. Overwhelming evidence now points to TPH2 as a candidate gene for 5-HT-related psychiatric disorders. To assess the role of TPH2 gene variability in the etiology of psychiatric diseases we performed cDNA sequence analysis of TPH2 transcripts from human post mortem amygdala samples obtained from individuals with psychiatric disorders (drug abuse, schizophrenia, suicide) and controls. Here we show that TPH2 exists in two alternatively spliced variants in the coding region, denoted TPH2a and TPH2b. Moreover, we found evidence that the pre-mRNAs of both splice variants are dynamically RNA-edited in a mutually exclusive manner. Kinetic studies with cell lines expressing recombinant TPH2 variants revealed a higher activity of the novel TPH2B protein compared with the previously known TPH2A, whereas RNA editing was shown to inhibit the enzymatic activity of both TPH2 splice variants. Therefore, our results strongly suggest a complex fine-tuning of central nervous system 5-HT biosynthesis by TPH2 alternative splicing and RNA editing. Finally, we present molecular and large-scale linkage data evidencing that deregulated alternative splicing and RNA editing is involved in the etiology of psychiatric diseases, such as suicidal behaviour. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 17 | Behav. Genet. 2011 Sep 41: 709-15 |
| PMID | 21399903 |
| Title | Effect of serotonin-related gene polymorphisms on pathogenesis and treatment response in Korean schizophrenic patients. |
| Abstract | Serotonin has been implicated in the pathophysiology of several psychiatric disorders including schizophrenia. Serotonergic system-related genes may be good candidates in investigating the genetic basis of schizophrenia. We aimed to investigate the associations of HTR1A C-1019G, HTR2A-1438A/G, TPH1 218A/C, and TPH2-703G/T variants with schizophrenia. A total of 202 patients with schizophrenia and 165 normal controls were genotyped for HTR1A C-1019G, HTR2A-1438A/G, TPH1 218A/C, and TPH2-703G/T single nucleotide polymorphisms (SNPs). In order to assess the severity of a patient's psychiatric symptoms, the brief psychiatric rating scale (BPRS), the positive and negative symptom scale (PANSS), and the Calgary depression scale for schizophrenia (CDSS) were administered. Genotype and allele frequencies were compared between groups via ?(2) statistics. Associations between the genotypes of candidate SNPs with the severity of symptoms were examined with ANOVA by comparing the mean scores of BPRS, PANSS, and CDSS according to genotype. No significant differences in the genotype distributions and allele frequencies of four SNPs were found between patients with schizophrenia and normal controls. There was a trend towards association of HTR1A C-1019G polymorphism with negative symptom. Negative symptom score of PANSS was lower in the patients with CC genotype than in the G allele carriers. These results suggested that C allele might be associated with lesser negative symptom. More studies are needed to confirm these findings. In the future, we plan to study the associations between schizophrenia and other genetic polymorphisms. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 18 | Behav. Genet. 2011 Sep 41: 709-15 |
| PMID | 21399903 |
| Title | Effect of serotonin-related gene polymorphisms on pathogenesis and treatment response in Korean schizophrenic patients. |
| Abstract | Serotonin has been implicated in the pathophysiology of several psychiatric disorders including schizophrenia. Serotonergic system-related genes may be good candidates in investigating the genetic basis of schizophrenia. We aimed to investigate the associations of HTR1A C-1019G, HTR2A-1438A/G, TPH1 218A/C, and TPH2-703G/T variants with schizophrenia. A total of 202 patients with schizophrenia and 165 normal controls were genotyped for HTR1A C-1019G, HTR2A-1438A/G, TPH1 218A/C, and TPH2-703G/T single nucleotide polymorphisms (SNPs). In order to assess the severity of a patient's psychiatric symptoms, the brief psychiatric rating scale (BPRS), the positive and negative symptom scale (PANSS), and the Calgary depression scale for schizophrenia (CDSS) were administered. Genotype and allele frequencies were compared between groups via ?(2) statistics. Associations between the genotypes of candidate SNPs with the severity of symptoms were examined with ANOVA by comparing the mean scores of BPRS, PANSS, and CDSS according to genotype. No significant differences in the genotype distributions and allele frequencies of four SNPs were found between patients with schizophrenia and normal controls. There was a trend towards association of HTR1A C-1019G polymorphism with negative symptom. Negative symptom score of PANSS was lower in the patients with CC genotype than in the G allele carriers. These results suggested that C allele might be associated with lesser negative symptom. More studies are needed to confirm these findings. In the future, we plan to study the associations between schizophrenia and other genetic polymorphisms. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 19 | Psychiatry Res 2011 Aug 189: 26-32 |
| PMID | 21396719 |
| Title | Influence of TPH2 variants on diagnosis and response to treatment in patients with major depression, bipolar disorder and schizophrenia. |
| Abstract | The present study is aimed at exploring whether some single nucleotide polymorphisms (SNPs) within the tryptophan hydroxylase 2 gene (TPH2) could be associated with major depression (MD), bipolar disorder (BD) and schizophrenia and whether they could predict clinical outcomes in Korean in-patients treated with antidepressants, mood stabilizers and antipsychotics, respectively. One hundred forty-five patients with MD, 132 patients with BD, 221 patients with schizophrenia and 170 psychiatrically healthy controls were genotyped for six TPH2 SNPs (rs4570625, rs10748185, rs11179027, rs1386498, rs4469933, and rs17110747). Baseline and final clinical measures, including the Montgomery-Åsberg Depression Rating Scale (MADRS), Young Mania Rating Scale and Positive and Negative Syndrome Scale, for patients with MD, BD and schizophrenia, respectively were recorded. None of the SNPs under investigation were associated with MD, BD and schizophrenia. However, in patients with MD, the rs4570625-rs10748185 G-A haplotype was significantly associated with higher endpoint MADRS severity, though not with response. Our results suggest that TPH2 variants neither have a major role in MD, BD and schizophrenia nor in response to treatments. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 20 | PLoS ONE 2011 -1 6: e19239 |
| PMID | 21541283 |
| Title | Sim1 is a novel regulator in the differentiation of mouse dorsal raphe serotonergic neurons. |
| Abstract | Mesencephalic dopaminergic neurons (mDA) and serotonergic (5-HT) neurons are clinically important ventral neuronal populations. Degeneration of mDA is associated with Parkinson's disease; defects in the serotonergic system are related to depression, obsessive-compulsive disorder, and schizophrenia. Although these neuronal subpopulations reveal positional and developmental relationships, the developmental cascades that govern specification and differentiation of mDA or 5-HT neurons reveal missing determinants and are not yet understood. We investigated the impact of the transcription factor Sim1 in the differentiation of mDA and rostral 5-HT neurons in vivo using Sim1-/- mouse embryos and newborn pups, and in vitro by gain- and loss-of-function approaches. We show a selective significant reduction in the number of dorsal raphe nucleus (DRN) 5-HT neurons in Sim1-/- newborn mice. In contrast, 5-HT neurons of other raphe nuclei as well as dopaminergic neurons were not affected. Analysis of the underlying molecular mechanism revealed that tryptophan hydroxylase 2 (TPH2) and the transcription factor Pet1 are regulated by Sim1. Moreover, the transcription factor Lhx8 and the modulator of 5-HT(1A)-mediated neurotransmitter release, Rgs4, exhibit significant higher expression in ventral hindbrain, compared to midbrain and are target genes of Sim1. The results demonstrate for the first time a selective transcription factor dependence of the 5-HT cell groups, and introduce Sim1 as a regulator of DRN specification acting upstream of Pet1 and TPH2. Moreover, Sim1 may act to modulate serotonin release via regulating RGS4. Our study underscores that subpopulations of a common neurotransmitter phenotype use distinct combinations of transcription factors to control the expression of shared properties. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 21 | J. Mol. Neurosci. 2011 Mar 43: 406-11 |
| PMID | 20938755 |
| Title | Association study of tryptophan hydroxylase-2 gene in schizophrenia and its clinical features in Chinese Han population. |
| Abstract | schizophrenia is a chronic and severe mental illness which is characterized by the development of various detrimental clinical features, and its etiology still remains unknown. Based on the evidence from neurobiological and pharmacological research, dysfunctions in central serotonergic transmission may be involved in the development of schizophrenia. Tryptophan hydroxylase 2 (TPH2), a newly identified isoform of tryptophan hydroxylase (the rate limiting enzyme in the biosynthesis of serotonin), regulates the brain-specific serotonin synthesis. To further clarify the role of TPH2 in this disease, we performed a case-control study to examine the association of the TPH2 gene with schizophrenia and its clinical features. We genotyped three putative functional polymorphisms (rs4570625, rs7305115, and rs4290270) within the gene and carried out a case-control study consisting of 304 schizophrenia patients and 362 healthy subjects. The severity of psychotic symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). The frequencies of genotypes and alleles of rs4570625, rs7305115, and rs4290270 did not differ significantly between schizophrenic patients and controls. However, the PANSS positive symptom subcore was significantly associated with rs4570625 (P=0.022). These results suggest that rs4570625 of TPH2 may play an important role in the development of positive symptoms in Han Chinese schizophrenic patients. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 22 | J. Mol. Neurosci. 2011 Mar 43: 406-11 |
| PMID | 20938755 |
| Title | Association study of tryptophan hydroxylase-2 gene in schizophrenia and its clinical features in Chinese Han population. |
| Abstract | schizophrenia is a chronic and severe mental illness which is characterized by the development of various detrimental clinical features, and its etiology still remains unknown. Based on the evidence from neurobiological and pharmacological research, dysfunctions in central serotonergic transmission may be involved in the development of schizophrenia. Tryptophan hydroxylase 2 (TPH2), a newly identified isoform of tryptophan hydroxylase (the rate limiting enzyme in the biosynthesis of serotonin), regulates the brain-specific serotonin synthesis. To further clarify the role of TPH2 in this disease, we performed a case-control study to examine the association of the TPH2 gene with schizophrenia and its clinical features. We genotyped three putative functional polymorphisms (rs4570625, rs7305115, and rs4290270) within the gene and carried out a case-control study consisting of 304 schizophrenia patients and 362 healthy subjects. The severity of psychotic symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). The frequencies of genotypes and alleles of rs4570625, rs7305115, and rs4290270 did not differ significantly between schizophrenic patients and controls. However, the PANSS positive symptom subcore was significantly associated with rs4570625 (P=0.022). These results suggest that rs4570625 of TPH2 may play an important role in the development of positive symptoms in Han Chinese schizophrenic patients. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 23 | Schizophr. Res. 2012 May 137: 264-6 |
| PMID | 22342331 |
| Title | A two-stage case-control association study between the tryptophan hydroxylase 2 (TPH2) gene and schizophrenia in a Japanese population. |
| Abstract | -1 |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 24 | J. Mol. Neurosci. 2012 Jul 47: 465-9 |
| PMID | 22392150 |
| Title | Common variants in the TPH2 promoter confer susceptibility to paranoid schizophrenia. |
| Abstract | Serotonergic system-related genes may be good candidates in investigating the genetic basis of schizophrenia. Our previous study suggested that promoter region of tryptophan hydroxylase 2 gene (TPH2) may confer the susceptibility to paranoid schizophrenia. In this study, we investigated whether common variants within TPH2 promoter may predispose to paranoid schizophrenia in Han Chinese. A total of 509 patients who met DSM-IV criteria for paranoid schizophrenia and 510 matched healthy controls were recruited for this study. Five polymorphisms within TPH2 promoter region were tested. No statistically significant differences were found in allele or genotype frequencies between schizophrenic patients and healthy controls. The frequency of the rs4448731T-rs6582071A-rs7963803A-rs4570625T-rs11178997A haplotype was significantly higher in cases compared to the controls (P?=?0.003; OR?=?1.49; 95% CI, 1.15-1.95). Our results suggest that the common variants within TPH2 promoter are associated with paranoid schizophrenia in Han Chinese. Further studies in larger samples are warranted to elucidate the role of TPH2 in the etiology of paranoid schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 25 | J. Mol. Neurosci. 2012 Jul 47: 465-9 |
| PMID | 22392150 |
| Title | Common variants in the TPH2 promoter confer susceptibility to paranoid schizophrenia. |
| Abstract | Serotonergic system-related genes may be good candidates in investigating the genetic basis of schizophrenia. Our previous study suggested that promoter region of tryptophan hydroxylase 2 gene (TPH2) may confer the susceptibility to paranoid schizophrenia. In this study, we investigated whether common variants within TPH2 promoter may predispose to paranoid schizophrenia in Han Chinese. A total of 509 patients who met DSM-IV criteria for paranoid schizophrenia and 510 matched healthy controls were recruited for this study. Five polymorphisms within TPH2 promoter region were tested. No statistically significant differences were found in allele or genotype frequencies between schizophrenic patients and healthy controls. The frequency of the rs4448731T-rs6582071A-rs7963803A-rs4570625T-rs11178997A haplotype was significantly higher in cases compared to the controls (P?=?0.003; OR?=?1.49; 95% CI, 1.15-1.95). Our results suggest that the common variants within TPH2 promoter are associated with paranoid schizophrenia in Han Chinese. Further studies in larger samples are warranted to elucidate the role of TPH2 in the etiology of paranoid schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 26 | J. Psychopharmacol. (Oxford) 2012 May 26: 629-35 |
| PMID | 22158544 |
| Title | Boosting serotonin in the brain: is it time to revamp the treatment of depression? |
| Abstract | Abnormalities in serotonin systems are presumably linked to various psychiatric disorders including schizophrenia and depression. Medications intended for these disorders aim to either block the reuptake or the degradation of this neurotransmitter. In an alternative approach, efforts have been made to enhance serotonin levels through dietary manipulation of precursor levels with modest clinical success. In the last 30 years, there has been little improvement in the pharmaceutical management of depression, and now is the time to revisit therapeutic strategies for the treatment of this disease. Tryptophan hydroxylase (TPH) catalyzes the first and rate-limiting step in the biosynthesis of serotonin. A recently discovered isoform, TPH2, is responsible for serotonin biosynthesis in the brain. Learning how to activate this enzyme (and its polymorphic versions) may lead to a new, more selective generation of antidepressants, able to regulate the levels of serotonin in the brain with fewer side effects. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 27 | J Psychiatr Res 2012 Aug 46: 1073-80 |
| PMID | 22655589 |
| Title | Investigation of tryptophan hydroxylase 2 (TPH2) in schizophrenia and in the response to antipsychotics. |
| Abstract | Serotonergic transmission is considered relevant in the pathophysiology and the treatment of schizophrenia. Tryptophan hydroxylase (TPH) is the rate limiting enzyme in the biosynthesis of serotonin. While the TPH1 gene has been found to be associated with schizophrenia, studies focusing on TPH2 variants did not yield conclusive results for schizophrenia or the response to antipsychotic medication. We analyzed eleven TPH2 SNPs in two case-control samples consisting of 4453 individuals in total. Six SNPs were selected because of their potential functional relevance (rs4570625, rs11178997, rs11178998, rs7954758, rs7305115, and, rs4290270) and were supported by another 5 tagging SNPs selected based on HapMap LD information. In the discovery sample (1476 individuals), we observed a significant association with schizophrenia for rs10784941 (p = 0.009, OR minor G-allele 0.82 [0.71-0.95]) and rs4565946 (p = 0.011, OR minor T-allele 0.83 [0.71-0.96]). Association was also observed with a common rs4570625-rs4565946 haplotype (OR G-C haplotype 1.20 [1.02-1.40]; p = 0.0046). Single-marker associations could not be replicated in the replication sample consisting of 2977 individuals, but there was a strong trend regarding the rs4570625-rs4565946 G-C haplotype (OR 1.10 [0.98-1.24]; p(one-sided test) = 0.054). In smaller sub-samples, the rare rs4570625-rs4565946 T-T haplotype was associated with reduced processing speed (n = 193, p = 0.004) and sensorimotor gating (n = 68, p = 0.006) of schizophrenia patients. TPH2 variants and the rs4570625-rs4565946 G-C haplotype did not influence the beneficial response to antipsychotic drugs (n = 210) after four weeks of treatment administering the Positive and Negative Syndrome Scale of schizophrenia (PANSS). We also investigated the association of the SNPs to treatment response, but did not get significant results. In sum, our results argue for only a minor role of TPH2 in schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 28 | Behav Brain Funct 2014 -1 10: 26 |
| PMID | 25073638 |
| Title | Polymorphisms in genes implicated in dopamine, serotonin and noradrenalin metabolism suggest association with cerebrospinal fluid monoamine metabolite concentrations in psychosis. |
| Abstract | Homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) are the major monoamine metabolites in the central nervous system (CNS). Their cerebrospinal fluid (CSF) concentrations, reflecting the monoamine turnover rates in CNS, are partially under genetic influence and have been associated with schizophrenia. We have hypothesized that CSF monoamine metabolite concentrations represent intermediate steps between single nucleotide polymorphisms (SNPs) in genes implicated in monoaminergic pathways and psychosis. We have searched for association between 119 SNPs in genes implicated in monoaminergic pathways [tryptophan hydroxylase 1 (TPH1), TPH2, tyrosine hydroxylase (TH), DOPA decarboxylase (DDC), dopamine beta-hydroxylase (DBH), catechol-O-methyltransferase (COMT), monoamine oxidase A (MAOA) and MAOB] and monoamine metabolite concentrations in CSF in 74 patients with psychotic disorder. There were 42 nominally significant associations between SNPs and CSF monoamine metabolite concentrations, which exceeded the expected number (20) of nominal associations given the total number of tests performed. The strongest association (p = 0.0004) was found between MAOB rs5905512, a SNP previously reported to be associated with schizophrenia in men, and MHPG concentrations in men with psychotic disorder. Further analyses in 111 healthy individuals revealed that 41 of the 42 nominal associations were restricted to patients with psychosis and were absent in healthy controls. The present study suggests that altered monoamine turnover rates in CNS reflect intermediate steps in the associations between SNPs and psychosis. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 29 | Genet. Mol. Res. 2014 -1 13: 1497-507 |
| PMID | 24668623 |
| Title | TPH2 gene polymorphisms in the regulatory region are associated with paranoid schizophrenia in Northern Han Chinese. |
| Abstract | In the last years, serotonin (5-HT) has been related with the pathophysiology of several psychiatric disorders, including schizophrenia. Thus, genes related to the serotonergic (5-HTergic) system are good candidate genes for schizophrenia. The rate-limiting enzyme of 5-HT synthesis is tryptophan hydroxylase 2 (TPH2). Single nucleotide polymorphisms (SNPs) in the regulatory regions of TPH2 gene may affect gene expression and biosynthesis of 5-HT triggering to various neuropsychiatric disorders related to 5-HT dysfunction. The present study explored the association of SNPs within the TPH2 gene with paranoid schizophrenia in Han Chinese. A total of 164 patients with schizophrenia and 244 healthy controls were genotyped for six TPH2 SNPs (rs4570625, rs11178997, rs11178998, rs41317118, rs17110747, and rs41317114). Significant group differences were observed in the allele and genotype frequencies of rs4570625 and in the frequencies of GTA and TTA haplotypes corresponding to rs4570625-rs11178997-rs11178998. Our findings suggest that common genetic variations of TPH2 are likely to contribute to genetic susceptibility to paranoid schizophrenia in Han Chinese. Further studies in larger samples are needed to replicate this association. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 30 | Neuropsychopharmacology 2014 Apr 39: 1125-34 |
| PMID | 24196946 |
| Title | Stimulation of 5-HT2C receptors improves cognitive deficits induced by human tryptophan hydroxylase 2 loss of function mutation. |
| Abstract | Polymorphisms in the gene encoding the serotonin synthesis enzyme TPH2 have been identified in mental illnesses, including bipolar disorder, major depression, autism, schizophrenia, and ADHD. Deficits in cognitive flexibility and perseverative behaviors are shared common symptoms in these disorders. However, little is known about the impact of TPH2 gene variants on cognition. Mice expressing a human TPH2 variant (TPH2-KI) were used to investigate cognitive consequences of TPH2 loss of function and pharmacological treatments. We applied a recently developed behavioral assay, the automated H-maze, to study cognitive functions in TPH2-KI mice. This assay involves the consecutive discovery of three different rules: a delayed alternation task, a non-alternation task, and a delayed reversal task. Possible contribution of locomotion, reward, and sensory perception were also investigated. The expression of loss-of-function mutant TPH2 in mice was associated with impairments in reversal learning and cognitive flexibility, accompanied by perseverative behaviors similar to those observed in human clinical studies. Pharmacological restoration of 5-HT synthesis with 5-hydroxytryptophan or treatment with the 5-HT(2C) receptor agonist CP809.101 reduced cognitive deficits in TPH2-KI mice and abolished perseveration. In contrast, treatment with the psychostimulant methylphenidate exacerbated cognitive deficits in mutant mice. Results from this study suggest a contribution of TPH2 in the regulation of cognition. Furthermore, identification of a role for a 5-HT(2) receptor agonist as a cognition-enhancing agent in mutant mice suggests a potential avenue to explore for the personalized treatment of cognitive symptoms in humans with reduced 5-HT synthesis and TPH2 polymorphisms. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 31 | PLoS ONE 2015 -1 10: e0136422 |
| PMID | 26291320 |
| Title | Generation of a Tph2 Conditional Knockout Mouse Line for Time- and Tissue-Specific Depletion of Brain Serotonin. |
| Abstract | Serotonin has been gaining increasing attention during the last two decades due to the dual function of this monoamine as key regulator during critical developmental events and as neurotransmitter. Importantly, unbalanced serotonergic levels during critical temporal phases might contribute to the onset of neuropsychiatric disorders, such as schizophrenia and autism. Despite increasing evidences from both animal models and human genetic studies have underpinned the importance of serotonin homeostasis maintenance during central nervous system development and adulthood, the precise role of this molecule in time-specific activities is only beginning to be elucidated. Serotonin synthesis is a 2-step process, the first step of which is mediated by the rate-limiting activity of Tph enzymes, belonging to the family of aromatic amino acid hydroxylases and existing in two isoforms, Tph1 and TPH2, responsible for the production of peripheral and brain serotonin, respectively. In the present study, we generated and validated a conditional knockout mouse line, TPH2flox/flox, in which brain serotonin can be effectively ablated with time specificity. We demonstrated that the Cre-mediated excision of the third exon of TPH2 gene results in the production of a TPH2null allele in which we observed the near-complete loss of brain serotonin, as well as the growth defects and perinatal lethality observed in serotonin conventional knockouts. We also revealed that in mice harbouring the TPH2null allele, but not in wild-types, two distinct TPH2 mRNA isoforms are present, namely TPH2?3 and TPH2?3?4, with the latter showing an in-frame deletion of amino acids 84-178 and coding a protein that could potentially retain non-negligible enzymatic activity. As we could not detect Tph1 expression in the raphe, we made the hypothesis that the TPH2?3?4 isoform can be at the origin of the residual, sub-threshold amount of serotonin detected in the brain of TPH2null/null mice. Finally, we set up a tamoxifen administration protocol that allows an efficient, time-specific inactivation of brain serotonin synthesis. On the whole, we generated a suitable genetic tool to investigate how serotonin depletion impacts on time-specific events during central nervous system development and adulthood life. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 32 | Sci Rep 2015 -1 5: 11864 |
| PMID | 26154191 |
| Title | Metabolomics Approach Reveals Integrated Metabolic Network Associated with Serotonin Deficiency. |
| Abstract | Serotonin is an important neurotransmitter that broadly participates in various biological processes. While serotonin deficiency has been associated with multiple pathological conditions such as depression, schizophrenia, Alzheimer's disease and Parkinson's disease, the serotonin-dependent mechanisms remain poorly understood. This study therefore aimed to identify novel biomarkers and metabolic pathways perturbed by serotonin deficiency using metabolomics approach in order to gain new metabolic insights into the serotonin deficiency-related molecular mechanisms. Serotonin deficiency was achieved through pharmacological inhibition of tryptophan hydroxylase (Tph) using p-chlorophenylalanine (pCPA) or genetic knockout of the neuronal specific TPH2 isoform. This dual approach improved specificity for the serotonin deficiency-associated biomarkers while minimizing nonspecific effects of pCPA treatment or TPH2 knockout (TPH2-/-). Non-targeted metabolic profiling and a targeted pCPA dose-response study identified 21 biomarkers in the pCPA-treated mice while 17 metabolites in the TPH2-/- mice were found to be significantly altered compared with the control mice. These newly identified biomarkers were associated with amino acid, energy, purine, lipid and gut microflora metabolisms. Oxidative stress was also found to be significantly increased in the serotonin deficient mice. These new biomarkers and the overall metabolic pathways may provide new understanding for the serotonin deficiency-associated mechanisms under multiple pathological states. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 33 | Am. J. Med. Genet. B Neuropsychiatr. Genet. 2015 Jul -1: -1 |
| PMID | 26172220 |
| Title | Epistatic and gene wide effects in YWHA and aromatic amino hydroxylase genes across ADHD and other common neuropsychiatric disorders: Association with YWHAE. |
| Abstract | Monoamines critically modulate neurophysiological functions affected in several neuropsychiatric disorders. We therefore examined genes encoding key enzymes of catecholamine and serotonin biosynthesis (tyrosine and tryptophan hydroxylases-TH and TPH1/2) as well as their regulatory 14-3-3 proteins (encoded by YWHA-genes). Previous studies have focused mainly on the individual genes, but no analysis spanning this regulatory network has been reported. We explored interactions between these genes in Norwegian patients with adult attention deficit hyperactivity disorder (aADHD), followed by gene-complex association tests in four major neuropsychiatric conditions; childhood ADHD (cADHD), bipolar disorder, schizophrenia, and major depressive disorder. For interaction analyses, we evaluated 55 SNPs across these genes in a sample of 583 aADHD patients and 637 controls. For the gene-complex tests, we utilized the data from large-scale studies of The Psychiatric Genomics Consortium (PGC). The four major neuropsychiatric disorders were examined for association with each of the genes individually as well as in three complexes as follows: (1) TPH1 and YWHA-genes; (2) TH, TPH2 and YWHA-genes; and (3) all genes together. The results show suggestive epistasis between YWHAE and two other 14-3-3-genes - YWHAZ, YWHAQ - in aADHD (nominal P-value of 0.0005 and 0.0008, respectively). In PGC data, association between YWHAE and schizophrenia was noted (P?=?1.00E-05), whereas the combination of TPH1 and YWHA-genes revealed signs of association in cADHD, schizophrenia, and bipolar disorder. In conclusion, polymorphisms in the YWHA-genes and their targets may exert a cumulative effect in ADHD and related neuropsychiatric conditions, warranting the need for further investigation of these gene-complexes. © 2015 Wiley Periodicals, Inc. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 34 | Anal Bioanal Chem 2016 Apr 408: 2963-73 |
| PMID | 26780709 |
| Title | Lipidomic profiling of tryptophan hydroxylase 2 knockout mice reveals novel lipid biomarkers associated with serotonin deficiency. |
| Abstract | Serotonin is an important neurotransmitter that regulates a wide range of physiological, neuropsychological, and behavioral processes. Consequently, serotonin deficiency is involved in a wide variety of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, schizophrenia, and depression. The pathophysiological mechanisms underlying serotonin deficiency, particularly from a lipidomics perspective, remain poorly understood. This study therefore aimed to identify novel lipid biomarkers associated with serotonin deficiency by lipidomic profiling of tryptophan hydroxylase 2 knockout (TPH2-/-) mice. Using a high-throughput normal-/reversed-phase two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry (NP/RP 2D LC-QToF-MS) method, 59 lipid biomarkers encompassing glycerophospholipids (glycerophosphocholines, lysoglycerophosphocholines, glycerophosphoethanolamines, lysoglycerophosphoethanolamines glycerophosphoinositols, and lysoglycerophosphoinositols), sphingolipids (sphingomyelins, ceramides, galactosylceramides, glucosylceramides, and lactosylceramides) and free fatty acids were identified. Systemic oxidative stress in the TPH2-/- mice was significantly elevated, and a corresponding mechanism that relates the lipidomic findings has been proposed. In summary, this work provides preliminary findings that lipid metabolism is implicated in serotonin deficiency. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |