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Klauspeter Lesch - One of the best experts on this subject based on the ideXlab platform.
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altered behaviour dopamine and norepinephrine regulation in stressed mice heterozygous in TPH2 gene
Progress in Neuro-psychopharmacology & Biological Psychiatry, 2021Co-Authors: Tatyana Strekalova, Jonas Waider, Klauspeter Lesch, Anna Gorlova, Allan V Kalueff, Evgeniy Svirin, Raymond Cespuglio, Igor Pomytkin, Angelika G Schmittboehrer, Daniel C AnthonyAbstract:Gene-environment interaction (GxE) determines the vulnerability of an individual to a spectrum of stress-related neuropsychiatric disorders. Increased impulsivity, excessive aggression, and other behavioural characteristics are associated with variants within the tryptophan hydroxylase-2 (TPH2) gene, a key enzyme in brain serotonin synthesis. This phenotype is recapitulated in naive mice with complete, but not with partial TPH2 inactivation. TPH2 haploinsufficiency in animals reflects allelic variation of TPH2 facilitating the elucidation of respective GxE mechanisms. Recently, we showed excessive aggression and altered serotonin brain metabolism in heterozygous TPH2-deficient male mice (TPH2+/-) after predator stress exposure. Here, we sought to extend these studies by investigating aggressive and anxiety-like behaviours, sociability, and the brain metabolism of dopamine and noradrenaline. Separately, TPH2+/- mice were examined for exploration activity in a novel environment and for the potentiation of helplessness in the modified swim test (ModFST). Predation stress procedure increased measures of aggression, dominancy, and suppressed sociability in TPH2+/- mice, which was the opposite of that observed in control mice. Anxiety-like behaviour was unaltered in the mutants and elevated in controls. TPH2+/- mice exposed to environmental novelty or to the ModFST exhibited increased novelty exploration and no increase in floating behaviour compared to controls, which is suggestive of resilience to stress and despair. High-performance liquid chromatography (HPLC) revealed significant genotype-dependent differences in the metabolism of dopamine, and norepinephrine within the brain tissue. In conclusion, environmentally challenged TPH2+/- mice exhibit behaviours that resemble the behaviour of non-stressed null mutants, which reveals how GxE interaction studies can unmask latent genetically determined predispositions.
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reverse phenotyping can the phenotype following constitutive TPH2 gene inactivation in mice be transferred to children and adolescents with and without adhd
Brain and behavior, 2021Co-Authors: Klauspeter Lesch, Atae Akhrif, Arunima Roy, Katharina Peters, Marcel Romanos, Angelika G Schmittbohrer, Susanne NeufangAbstract:Introduction Experimental models of neuropsychiatric disorders, for example, ADHD, are used to mimic specific phenotypic traits of a complex human disorder. However, it remains unresolved to what extent the animal phenotype reflects the specific human trait. The null mutant mouse of the serotonin-synthesizing tryptophan hydroxylase-2 (TPH2-/- ) gene has been proposed as experimental model for ADHD with high face validity for impulsive, aggressive, and anxious behaviors. To validate this ADHD-like model, we examined the TPH2-/- phenotype in humans when considering allelic variation of TPH2 function ("reverse phenotyping"). Methods 58 participants (6 females, 8-18 years) were examined, of whom 32 were diagnosed with ADHD. All participants were phenotyped for impulsivity, aggression, and anxiety using questionnaires, behavioral tests, and MRI scanning while performing the 4-choice serial reaction time task. Additionally, participants were genotyped for the TPH2 G-703T (rs4570625) polymorphism. To analyze the relation between TPH2 G-703T variants and the impulsive/aggressive/anxious phenotype, mediation analyses were performed using behavioral and MRI data as potential mediators. Results We found that the relation between TPH2 G-703T and aggression as part of the reverse TPH2- /- phenotype was mediated by structure and function of the right middle and inferior frontal gyrus. Conclusion At the example of trait aggression, our results support the assumption that the TPH2 null mutant mouse reflects the TPH2 G-703T-dependent phenotype in humans. Additionally, we conclude that "reverse phenotyping" is a promising method to validate experimental models and human findings for refined analysis of disease mechanisms.
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increased functional coupling of 5 ht1a autoreceptors to girk channels in TPH2 mice
European Neuropsychopharmacology, 2017Co-Authors: Boris Mlinar, Jonas Waider, Klauspeter Lesch, Alberto Montalbano, Renato CorradettiAbstract:Firing activity of serotonergic neurons is under regulatory control by somatodendritic 5-HT1A autoreceptors (5-HT1AARs). Enhanced 5-HT1AAR functioning may cause decreased serotonergic signaling in brain and has thereby been implicated in the etiology of mood and anxiety disorders. Tryptophan hydroxylase-2 knockout (TPH2-/-) mice exhibit sensitization of 5-HT1A agonist-induced inhibition of serotonergic neuron firing and thus represents a unique animal model of enhanced 5-HT1AAR functioning. To elucidate the mechanisms underlying 5-HT1AAR supersensitivity in TPH2-/- mice, we characterized the activation of G protein-coupled inwardly-rectifying potassium (GIRK) conductance by the 5-HT1A receptor agonist 5-carboxamidotryptamine using whole-cell recordings from serotonergic neurons in dorsal raphe nucleus. TPH2-/- mice exhibited a mean twofold leftward shift of the agonist concentration-response curve (p < 0.001) whereas the maximal response, proportional to the 5-HT1AAR number, was not different (p = 0.42) compared to TPH2+/- and TPH2+/+ littermates. No differences were found in the basal inwardly-rectifying potassium conductance, determined in the absence of agonist, (p = 0.80) nor in total GIRK conductance activated by intracellular application of GTP-γ-S (p = 0.69). These findings indicate increased functional coupling of 5-HT1AARs to GIRK channels in TPH2-/- mice without a concomitant increase in 5-HT1AARs and/or GIRK channel density. In addition, no changes were found in α1-adrenergic facilitation of firing (p = 0.72) indicating lack of adaptive changes TPH2-/- mice. 5-HT1AAR supersensitivity may represents a previously unrecognized cause of serotonergic system hypofunction and associated disorders and provides a possible explanation for conflicting results on the correlation between 5-HT1AAR density and depression in clinical imaging studies.
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cellular resilience 5 ht neurons in TPH2 mice retain normal firing behavior despite the lack of brain 5 ht
European Neuropsychopharmacology, 2015Co-Authors: Alberto Montalbano, Jonas Waider, Klauspeter Lesch, Mario Barbieri, Ozan Baytas, Renato Corradetti, Boris MlinarAbstract:Considerable evidence links dysfunction of serotonin (5-hydroxytryptamine, 5-HT) transmission to neurodevelopmental and psychiatric disorders characterized by compromised "social" cognition and emotion regulation. It is well established that the brain 5-HT system is under autoregulatory control by its principal transmitter 5-HT via its effects on activity and expression of 5-HT system-related proteins. To examine whether 5-HT itself also has a crucial role in the acquisition and maintenance of characteristic rhythmic firing of 5-HT neurons, we compared their intrinsic electrophysiological properties in mice lacking brain 5-HT, i.e. tryptophan hydroxylase-2 null mice (TPH2(-/-)) and their littermates, TPH2(+/-) and TPH2(+/+), by using whole-cell patch-clamp recordings in a brainstem slice preparation and single unit recording in anesthetized animals. We report that the active properties of dorsal raphe nucleus (DRN) 5-HT neurons in vivo (firing rate magnitude and variability; the presence of spike doublets) and in vitro (firing in response to depolarizing current pulses; action potential shape) as well as the resting membrane potential remained essentially unchanged across TPH2 genotypes. However, there were subtle differences in subthreshold properties, most notably, an approximately 25% higher input conductance in TPH2(-/-) mice compared with TPH2(+/-) and TPH2(+/+) littermates (p<0.0001). This difference may at least in part be a consequence of slightly bigger size of the DRN 5-HT neurons in TPH2(-/-) mice (approximately 10%, p<0.0001). Taken together, these findings show that 5-HT neurons acquire and maintain their signature firing properties independently of the presence of their principal neurotransmitter 5-HT, displaying an unexpected functional resilience to complete brain 5-HT deficiency.
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GABA concentration and GABAergic neuron populations in limbic areas are differentially altered by brain serotonin deficiency in TPH2 knockout mice
Histochemistry and Cell Biology, 2013Co-Authors: Jonas Waider, Klauspeter Lesch, Florian Proft, Georg Langlhofer, Esther Asan, Lise GutknechtAbstract:While tryptophan hydroxylase-2 ( TPH2 ) null mutant ( TPH2 ^−/−) mice are completely deficient in brain serotonin (5-HT) synthesis, the formation of serotonergic neurons and pathfinding of their projections are not impaired. However, 5-HT deficiency, during development and in the adult, might affect morphological and functional parameters of other neural systems. To assess the influence of 5-HT deficiency on γ-amino butyric acid (GABA) systems, we carried out measurements of GABA concentrations in limbic brain regions of adult male wildtype ( wt ), heterozygous ( TPH2 ^+/−) and TPH2 ^−/− mice. In addition, unbiased stereological estimation of GABAergic interneuron numbers and density was performed in subregions of amygdala and hippocampus. Amygdala and prefrontal cortex displayed significantly increased and decreased GABA concentrations, respectively, exclusively in TPH2 ^+/− mice while no changes were detected between TPH2 ^−/− and wt mice. In contrast, in the hippocampus, increased GABA concentrations were found in TPH2 ^−/− mice. While total cell density in the anterior basolateral amygdala did not differ between genotypes, the number and density of the GABAergic interneurons were significantly decreased in TPH2 ^−/− mice, with the group of parvalbumin (PV)-immunoreactive (ir) interneurons contributing somewhat less to the decrease than that of non-PV-ir GABAergic interneurons. Major morphological changes were also absent in the dorsal hippocampus, and only a trend toward reduced density of PV-ir cells was observed in the CA3 region of TPH2 ^−/− mice. Our findings are the first to document that life-long reduction or complete lack of brain 5-HT transmission causes differential changes of GABA systems in limbic regions which are key players in emotional learning and memory processes. The changes likely reflect a combination of developmental alterations and functional adaptations of emotion circuits to balance the lack of 5-HT, and may underlie altered emotional behavior in 5-HT-deficient mice. Taken together, our findings provide further insight into the mechanisms how life-long 5-HT deficiency impacts the pathogenesis of anxiety- and fear-related disorders.
Lise Gutknecht - One of the best experts on this subject based on the ideXlab platform.
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interaction of brain 5 ht synthesis deficiency chronic stress and sex differentially impact emotional behavior in TPH2 knockout mice
Psychopharmacology, 2015Co-Authors: Sandy Popp, Lise Gutknecht, Andreas Reif, Jonas Waider, Frank M J Sommerlandt, Corinna Goppner, Antonia Post, Daniel L A Van Den Hove, Tatyana StrekalovaAbstract:Rationale While brain serotonin (5-HT) function is implicated in gene-by-environment interaction (GxE) impacting the vulnerability-resilience continuum in neuropsychiatric disorders, it remains elusive how the interplay of altered 5-HTsynthesis and environmental stressors is linked to failure in emotion regulation. Objective Here, we investigated the effect of constitutively impaired 5-HT synthesis on behavioral and neuroendocrine responses to unpredictable chronic mild stress (CMS) using a mouse model of brain 5-HT deficiency resulting from targeted inactivation of the tryptophan hydroxylase-2 (TPH2) gene. Results Locomotor activity and anxiety- and depression-like behavior as well as conditioned fear responses were differentially affected by TPH2 genotype, sex, and CMS. TPH2 null mutants (TPH2 �/� ) displayed increased general metabolism, marginally reduced anxiety- and depression-like behavior but strikingly increased conditioned fear responses. Behavioral modifications were associated with sex-specific hypothalamic-pituitaryadrenocortical (HPA) system alterations as indicated by plasma corticosterone and fecal corticosterone metabolite concentrations. TPH2 �/� males displayed increased impulsivity and high aggressiveness. TPH2 �/� females displayed greater emotional
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GABA concentration and GABAergic neuron populations in limbic areas are differentially altered by brain serotonin deficiency in TPH2 knockout mice
Histochemistry and Cell Biology, 2013Co-Authors: Jonas Waider, Klauspeter Lesch, Florian Proft, Georg Langlhofer, Esther Asan, Lise GutknechtAbstract:While tryptophan hydroxylase-2 ( TPH2 ) null mutant ( TPH2 ^−/−) mice are completely deficient in brain serotonin (5-HT) synthesis, the formation of serotonergic neurons and pathfinding of their projections are not impaired. However, 5-HT deficiency, during development and in the adult, might affect morphological and functional parameters of other neural systems. To assess the influence of 5-HT deficiency on γ-amino butyric acid (GABA) systems, we carried out measurements of GABA concentrations in limbic brain regions of adult male wildtype ( wt ), heterozygous ( TPH2 ^+/−) and TPH2 ^−/− mice. In addition, unbiased stereological estimation of GABAergic interneuron numbers and density was performed in subregions of amygdala and hippocampus. Amygdala and prefrontal cortex displayed significantly increased and decreased GABA concentrations, respectively, exclusively in TPH2 ^+/− mice while no changes were detected between TPH2 ^−/− and wt mice. In contrast, in the hippocampus, increased GABA concentrations were found in TPH2 ^−/− mice. While total cell density in the anterior basolateral amygdala did not differ between genotypes, the number and density of the GABAergic interneurons were significantly decreased in TPH2 ^−/− mice, with the group of parvalbumin (PV)-immunoreactive (ir) interneurons contributing somewhat less to the decrease than that of non-PV-ir GABAergic interneurons. Major morphological changes were also absent in the dorsal hippocampus, and only a trend toward reduced density of PV-ir cells was observed in the CA3 region of TPH2 ^−/− mice. Our findings are the first to document that life-long reduction or complete lack of brain 5-HT transmission causes differential changes of GABA systems in limbic regions which are key players in emotional learning and memory processes. The changes likely reflect a combination of developmental alterations and functional adaptations of emotion circuits to balance the lack of 5-HT, and may underlie altered emotional behavior in 5-HT-deficient mice. Taken together, our findings provide further insight into the mechanisms how life-long 5-HT deficiency impacts the pathogenesis of anxiety- and fear-related disorders.
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brain specific conditional and time specific inducible TPH2 knockout mice possess normal serotonergic gene expression in the absence of serotonin during adult life
Neurochemistry International, 2010Co-Authors: C Kriegebaum, Lise Gutknecht, Andreas Reif, Angelika Schmitt, Ningning Song, Ying Huang, Yuqiang Ding, Klauspeter LeschAbstract:Several lines of evidence implicate a dysregulation of tryptophan hydroxylase (TPH)-dependent serotonin (5-HT) synthesis in emotional behaviour and stress, and point to its relevance for the etiology and pathogenesis of various neuropsychiatric disorders. We therefore studied different animal models featuring reduced TPH2 expression to investigate the consequences of impaired brain 5-HT synthesis on neuronal development. Specifically, brain-specific conditional and time-specific inducible TPH2 knockout (KO) models were generated and investigated for altered serotonergic neuron-specific gene expression. Raphe neurons of a brain-specific constitutive TPH2 KO were completely devoid of TPH2-positive neurons and, consequently, 5-HT in the brain, and also displayed no compensatory up-regulation of Tph1 expression. In contrast, an inducible TPH2 KO mouse facilitates the generation of a brain-specific 5-HT-reduction model selectively during adult life. This resulted in a highly reduced number of TPH2-positive cells and thus 5-HT in the brain. Intriguingly, expression studies detected no alteration in the expression of genes relevant to the 5-HT system in the brain-specific TPH2 KO and the 5-HT-reduction models. These findings confirm the specificity of TPH2 in brain 5-HT synthesis across the lifespan, yet also suggest that neither developmental nor adult 5-HT synthesis is required for the expression of genes specific for serotonergic signalling. The formation of the serotonergic system thus seems to be a preserved expressional pattern due to intrinsic cellular programs which occurs also in the absence of its key molecule, namely 5-HT.
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spatio temporal expression of tryptophan hydroxylase isoforms in murine and human brain convergent data from TPH2 knockout mice
European Neuropsychopharmacology, 2009Co-Authors: Lise Gutknecht, C Kriegebaum, Jonas Waider, Angelika Schmitt, Klauspeter LeschAbstract:Dysregulation of tryptophan hydroxylase (TPH)-dependent serotonin (5-HT) synthesis, has been implicated in various neuropsychiatric disorders, although the differential expression pattern of the two isoforms is controversial. Here, we report a comprehensive spatio-temporal isoform-specific analysis of TPH1 and TPH2 expression during pre- and postnatal development of mouse brain and in adult human brain. TPH2 expression was consistently detected in the raphe nuclei, as well as in fibers in the deep pineal gland and in small intestine. Although TPH1 expression was found in these peripheral tissues, no significant TPH1 expression was detected in the brain, neither during murine development, nor in mouse and human adult brain. In support of TPH2 specificity in brain 5-HT synthesis, raphe neurons of TPH2 knockout mice were completely devoid of 5-HT, with no compensatory activation of Tph1 expression. In conclusion, our findings indicate that brain 5-HT synthesis across the lifespan is exclusively maintained by TPH2.
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deficiency of brain 5 ht synthesis but serotonergic neuron formation in TPH2 knockout mice
Journal of Neural Transmission, 2008Co-Authors: Lise Gutknecht, Andreas Reif, C Kriegebaum, Jonas Waider, Stefanie Kraft, A Bettina E Holtmann, Angelika Schmitt, Klauspeter LeschAbstract:The relative contribution of the two tryptophan hydroxylase (TPH) isoforms, TPH1 and TPH2, to brain serotonergic system function is controversial. To investigate the respective role of TPH2 in neuron serotonin (5-HT) synthesis and the role of 5-HT in brain development, mice with a targeted disruption of TPH2 were generated. The preliminary results indicate that in TPH2 knockout mice raphe neurons are completely devoid of 5-HT, whereas no obvious alteration in morphology and fiber distribution are observed. The findings confirm the exclusive specificity of TPH2 in brain 5-HT synthesis and suggest that TPH2-synthesized 5-HT is not required for serotonergic neuron formation.
Donald M Kuhn - One of the best experts on this subject based on the ideXlab platform.
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tryptophan hydroxylase 2 aggregates through disulfide cross linking upon oxidation possible link to serotonin deficits and non motor symptoms in parkinson s disease
Journal of Neurochemistry, 2011Co-Authors: Donald M Kuhn, Timothy J Geddes, Catherine E Sykes, Karen Eskow L Jaunarajs, Christopher BishopAbstract:Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopamine neurons of the nigrostriatal system, resulting in severe motor disturbances. Although much less appreciated, non-motor symptoms are also very common in PD and many can be traced to serotonin neuronal deficits. Tryptophan hydroxylase (TPH) 2, the rate-limiting enzyme in the serotonin biosynthesis, is a phenotypic marker for serotonin neurons and is known to be extremely labile to oxidation. Therefore, the oxidative processes that prevail in PD could cause TPH2 misfolding and modify serotonin neuronal function much as is seen in dopamine neurons. Oxidation of TPH2 inhibits enzyme activity and leads to the formation of high molecular weight aggregates in a dithiothreitol-reversible manner. Cysteine-scanning mutagenesis shows that as long as a single cysteine residue (out of a total of 13 per monomer) remains in TPH2, it cross-links upon oxidation and only cysteine-less mutants are resistant to this effect. The effects of oxidants on TPH2 catalytic function and cross-linking are also observed in intact TPH2-expressing HEK293 cells. Oxidation shifts TPH2 from the soluble compartment into membrane fractions and large inclusion bodies. Sequential non-reducing/reducing 2-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting confirmed that TPH2 was one of a small number of cytosolic proteins that form disulfide-bonded aggregates. The propensity of TPH2 to misfold upon oxidation of its cysteine residues is responsible for its catalytic lability and may be related to loss of serotonin neuronal function in PD and the emergence of non-motor (psychiatric) symptoms.
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phosphorylation and activation of tryptophan hydroxylase 2 identification of serine 19 as the substrate site for calcium calmodulin dependent protein kinase ii
Journal of Neurochemistry, 2007Co-Authors: Donald M Kuhn, Stacey A Sakowski, Timothy J Geddes, Curtis G Wilkerson, John W HaycockAbstract:Tryptophan hydroxylase (TPH) is the initial and rate-limiting enzyme in the biosynthesis of serotonin. TPH was once thought to be a single-gene product but it is now known to exist in two isoforms. TPH1 is found in the periphery and pineal gland whereas TPH2 is expressed specifically in the CNS. Both TPH isoforms are known to be regulated by protein kinase-dependent phosphorylation and the sites of modification of TPH1 by protein kinase A have been identified. While TPH2 is activated by calcium, calmodulin-dependent protein kinase II (CaMKII), the sites at which this isoform is modified are not known. Treatment of wild-type TPH2 with CaMKII followed by mass spectrometry analysis revealed that the enzyme was activated and phosphorylated at a single site, serine-19. Mutagenesis of serine-19 to alanine did not alter the catalytic function of TPH2 but this mutant enzyme was neither activated nor phosphorylated by CaMKII. A phosphopeptide bracketing phosphoserine-19 in TPH2 was used as an antigen to generate polyclonal antibodies against phosphoserine-19. The antibodies are highly specific for phosphoserine-19 in TPH2. The antibodies do not react with wild-type TPH2 or TPH1 and they do not recognize phophoserine-58 or phosphoserine-260 in TPH1. These results establish that activation of TPH2 by CaMKII is mediated by phosphorylation of serine-19 within the regulatory domain of the enzyme. Production of a specific antibody against the CaMKII phosphorylation site in TPH2 represents a valuable tool to advance the study of the mechanisms regulating the function of this important enzyme.
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differential tissue distribution of tryptophan hydroxylase isoforms 1 and 2 as revealed with monospecific antibodies
Brain Research, 2006Co-Authors: Stacey A Sakowski, Timothy J Geddes, David M Thomas, Edi Levi, James S Hatfield, Donald M KuhnAbstract:Abstract Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of the neurotransmitter serotonin. Once thought to be a single-gene product, TPH is now known to exist in two isoforms—TPH1 is found in the pineal and gut, and TPH2 is selectively expressed in brain [Walther, D.J., Peter, J.U., Bashammakh, S., Hortnagl, H., Voits, M., Fink, H., Bader, M., 2003. Synthesis of serotonin by a second tryptophan hydroxylase isoform. Science 299, 76.]. Heretofore, probes used for localization of TPH protein or mRNA could not distinguish between the TPH isoforms because of extensive homology shared by them at the nucleotide and amino acid level. We have produced monospecific polyclonal antibodies against TPH1 and TPH2 using peptide antigens from nonoverlapping sequences in the respective proteins. These antibodies allow the differentiation of TPH1 and TPH2 upon immunoblotting, immunoprecipitation, and immunocytochemical staining of tissue sections from brain and gut. TPH1 and TPH2 antibodies do not cross-react with either tyrosine hydroxylase or phenylalanine hydroxylase. Analysis of mouse tissues confirms that TPH1 is the predominant form expressed in pineal gland and in P815 mastocytoma cells with a molecular weight of 51 kDa. TPH2 is the predominant enzyme form expressed in brain extracts from mesencephalic tegmentum, striatum, and hippocampus with a molecular weight of 56 kDa. Antibody specificity against TPH1 and TPH2 is retained across mouse, rat, rabbit, primate, and human tissues. Antibodies that distinguish between the isoforms of TPH will allow studies of the differential regulation of their expression in brain and periphery.
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mouse tryptophan hydroxylase isoform 2 and the role of proline 447 in enzyme function
Journal of Neurochemistry, 2006Co-Authors: Stacey A Sakowski, Donald M Kuhn, Timothy J GeddesAbstract:Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of the neurotransmitter serotonin (5-HT). Once thought to be a single gene product, TPH is now known to exist in two isoforms. Isoform 1 (TPH1) is found in the pineal gland and gut, and isoform 2 (TPH2) is selectively expressed in brain. A single-nucleotide polymorphism in TPH2 results in a proline-to-arginine mutation at residue 447 and substantially lowers catalytic activity. In view of the importance of TPH in determining brain 5-HT function, we cloned TPH2 and produced the P447R mutant to assess the importance of this proline in enzyme function. Catalytically active TPH2 and the P447R mutant were expressed at the predicted subunit molecular mass of 56 kDa. The P447R mutant expressed less than 50% of the activity of TPH2. Mutation of this conserved proline in TPH1 (P403R) also resulted in an enzyme with significantly lower activity than the wild-type enzyme. The P447R mutant had a Vmax 50% lower than that of TPH2. The P447R mutation did not alter the oligomeric assembly of the protein, nor change its responsiveness to cysteine modification. The P447R mutation did not alter enzyme substrate specificity or stability, but conferred slightly enhanced sensitivity to inhibition by dopamine and diminished sensitivity to iron in catalysis. The conserved proline in TPH (residue 447 in TPH2 and 403 in TPH1) plays an important role in enzyme function by regulating Vmax of the catalytic reaction.
Jonas Waider - One of the best experts on this subject based on the ideXlab platform.
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altered behaviour dopamine and norepinephrine regulation in stressed mice heterozygous in TPH2 gene
Progress in Neuro-psychopharmacology & Biological Psychiatry, 2021Co-Authors: Tatyana Strekalova, Jonas Waider, Klauspeter Lesch, Anna Gorlova, Allan V Kalueff, Evgeniy Svirin, Raymond Cespuglio, Igor Pomytkin, Angelika G Schmittboehrer, Daniel C AnthonyAbstract:Gene-environment interaction (GxE) determines the vulnerability of an individual to a spectrum of stress-related neuropsychiatric disorders. Increased impulsivity, excessive aggression, and other behavioural characteristics are associated with variants within the tryptophan hydroxylase-2 (TPH2) gene, a key enzyme in brain serotonin synthesis. This phenotype is recapitulated in naive mice with complete, but not with partial TPH2 inactivation. TPH2 haploinsufficiency in animals reflects allelic variation of TPH2 facilitating the elucidation of respective GxE mechanisms. Recently, we showed excessive aggression and altered serotonin brain metabolism in heterozygous TPH2-deficient male mice (TPH2+/-) after predator stress exposure. Here, we sought to extend these studies by investigating aggressive and anxiety-like behaviours, sociability, and the brain metabolism of dopamine and noradrenaline. Separately, TPH2+/- mice were examined for exploration activity in a novel environment and for the potentiation of helplessness in the modified swim test (ModFST). Predation stress procedure increased measures of aggression, dominancy, and suppressed sociability in TPH2+/- mice, which was the opposite of that observed in control mice. Anxiety-like behaviour was unaltered in the mutants and elevated in controls. TPH2+/- mice exposed to environmental novelty or to the ModFST exhibited increased novelty exploration and no increase in floating behaviour compared to controls, which is suggestive of resilience to stress and despair. High-performance liquid chromatography (HPLC) revealed significant genotype-dependent differences in the metabolism of dopamine, and norepinephrine within the brain tissue. In conclusion, environmentally challenged TPH2+/- mice exhibit behaviours that resemble the behaviour of non-stressed null mutants, which reveals how GxE interaction studies can unmask latent genetically determined predispositions.
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stress induced aggression in heterozygous TPH2 mutant mice is associated with alterations in serotonin turnover and expression of 5 ht6 and ampa subunit 2a receptors
Journal of Affective Disorders, 2020Co-Authors: Jonas Waider, Anna Gorlova, G Ortega, Natalia Bazhenova, Ekaterina Veniaminova, Andrey Proshin, Allan V KalueffAbstract:Abstract Background The contribution of gene-environment interactions that lead to excessive aggression is poorly understood. Environmental stressors and mutations of the gene encoding tryptophan hydroxylase-2 (TPH2) are known to influence aggression. For example, TPH2 null mutant mice (TPH2−/−) are naturally highly aggressive, while heterozygous mice (TPH2+/−) lack a behavioral phenotype and are considered endophenotypically normal. Here we sought to discover whether an environmental stressor would affect the phenotype of the genetically ‘susceptible’ heterozygous mice (TPH2+/−). Methods TPH2+/− male mice or TPH2+/+ controls were subjected to a five-day long rat exposure stress paradigm. Brain serotonin metabolism and the expression of selected genes encoding serotonin receptors, AMPA receptors, and stress markers were studied. Results Stressed TPH2+/− mice displayed increased levels of aggression and social dominance, whereas TPH2+/+ animals became less aggressive and less dominant. Brain tissue concentrations of serotonin, its precursor hydroxytryptophan and its metabolite 5-hydroxyindoleacetic acid were significantly altered in all groups in the prefrontal cortex, striatum, amygdala, hippocampus and dorsal raphe after stress. Compared to non-stressed animals, the concentration of 5-hydroxytryptophan was elevated in the amygdala though decreased in the other brain structures. The overexpression of the AMPA receptor subunit, GluA2, and downregulation of 5-HT6 receptor, as well as overexpression of c-fos and glycogen-synthase-kinase-3β (GSK3-β), were found in most structures of the stressed TPH2+/− mice. Limitations Rescue experiments would help to verify causal relationships of reported changes. Conclusions The interaction of a partial TPH2 gene deficit with stress results in pathological aggression and molecular changes, and suggests that the presence of genetic susceptibility can augment aggression in seemingly resistant phenotypes.
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increased functional coupling of 5 ht1a autoreceptors to girk channels in TPH2 mice
European Neuropsychopharmacology, 2017Co-Authors: Boris Mlinar, Jonas Waider, Klauspeter Lesch, Alberto Montalbano, Renato CorradettiAbstract:Firing activity of serotonergic neurons is under regulatory control by somatodendritic 5-HT1A autoreceptors (5-HT1AARs). Enhanced 5-HT1AAR functioning may cause decreased serotonergic signaling in brain and has thereby been implicated in the etiology of mood and anxiety disorders. Tryptophan hydroxylase-2 knockout (TPH2-/-) mice exhibit sensitization of 5-HT1A agonist-induced inhibition of serotonergic neuron firing and thus represents a unique animal model of enhanced 5-HT1AAR functioning. To elucidate the mechanisms underlying 5-HT1AAR supersensitivity in TPH2-/- mice, we characterized the activation of G protein-coupled inwardly-rectifying potassium (GIRK) conductance by the 5-HT1A receptor agonist 5-carboxamidotryptamine using whole-cell recordings from serotonergic neurons in dorsal raphe nucleus. TPH2-/- mice exhibited a mean twofold leftward shift of the agonist concentration-response curve (p < 0.001) whereas the maximal response, proportional to the 5-HT1AAR number, was not different (p = 0.42) compared to TPH2+/- and TPH2+/+ littermates. No differences were found in the basal inwardly-rectifying potassium conductance, determined in the absence of agonist, (p = 0.80) nor in total GIRK conductance activated by intracellular application of GTP-γ-S (p = 0.69). These findings indicate increased functional coupling of 5-HT1AARs to GIRK channels in TPH2-/- mice without a concomitant increase in 5-HT1AARs and/or GIRK channel density. In addition, no changes were found in α1-adrenergic facilitation of firing (p = 0.72) indicating lack of adaptive changes TPH2-/- mice. 5-HT1AAR supersensitivity may represents a previously unrecognized cause of serotonergic system hypofunction and associated disorders and provides a possible explanation for conflicting results on the correlation between 5-HT1AAR density and depression in clinical imaging studies.
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cellular resilience 5 ht neurons in TPH2 mice retain normal firing behavior despite the lack of brain 5 ht
European Neuropsychopharmacology, 2015Co-Authors: Alberto Montalbano, Jonas Waider, Klauspeter Lesch, Mario Barbieri, Ozan Baytas, Renato Corradetti, Boris MlinarAbstract:Considerable evidence links dysfunction of serotonin (5-hydroxytryptamine, 5-HT) transmission to neurodevelopmental and psychiatric disorders characterized by compromised "social" cognition and emotion regulation. It is well established that the brain 5-HT system is under autoregulatory control by its principal transmitter 5-HT via its effects on activity and expression of 5-HT system-related proteins. To examine whether 5-HT itself also has a crucial role in the acquisition and maintenance of characteristic rhythmic firing of 5-HT neurons, we compared their intrinsic electrophysiological properties in mice lacking brain 5-HT, i.e. tryptophan hydroxylase-2 null mice (TPH2(-/-)) and their littermates, TPH2(+/-) and TPH2(+/+), by using whole-cell patch-clamp recordings in a brainstem slice preparation and single unit recording in anesthetized animals. We report that the active properties of dorsal raphe nucleus (DRN) 5-HT neurons in vivo (firing rate magnitude and variability; the presence of spike doublets) and in vitro (firing in response to depolarizing current pulses; action potential shape) as well as the resting membrane potential remained essentially unchanged across TPH2 genotypes. However, there were subtle differences in subthreshold properties, most notably, an approximately 25% higher input conductance in TPH2(-/-) mice compared with TPH2(+/-) and TPH2(+/+) littermates (p<0.0001). This difference may at least in part be a consequence of slightly bigger size of the DRN 5-HT neurons in TPH2(-/-) mice (approximately 10%, p<0.0001). Taken together, these findings show that 5-HT neurons acquire and maintain their signature firing properties independently of the presence of their principal neurotransmitter 5-HT, displaying an unexpected functional resilience to complete brain 5-HT deficiency.
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interaction of brain 5 ht synthesis deficiency chronic stress and sex differentially impact emotional behavior in TPH2 knockout mice
Psychopharmacology, 2015Co-Authors: Sandy Popp, Lise Gutknecht, Andreas Reif, Jonas Waider, Frank M J Sommerlandt, Corinna Goppner, Antonia Post, Daniel L A Van Den Hove, Tatyana StrekalovaAbstract:Rationale While brain serotonin (5-HT) function is implicated in gene-by-environment interaction (GxE) impacting the vulnerability-resilience continuum in neuropsychiatric disorders, it remains elusive how the interplay of altered 5-HTsynthesis and environmental stressors is linked to failure in emotion regulation. Objective Here, we investigated the effect of constitutively impaired 5-HT synthesis on behavioral and neuroendocrine responses to unpredictable chronic mild stress (CMS) using a mouse model of brain 5-HT deficiency resulting from targeted inactivation of the tryptophan hydroxylase-2 (TPH2) gene. Results Locomotor activity and anxiety- and depression-like behavior as well as conditioned fear responses were differentially affected by TPH2 genotype, sex, and CMS. TPH2 null mutants (TPH2 �/� ) displayed increased general metabolism, marginally reduced anxiety- and depression-like behavior but strikingly increased conditioned fear responses. Behavioral modifications were associated with sex-specific hypothalamic-pituitaryadrenocortical (HPA) system alterations as indicated by plasma corticosterone and fecal corticosterone metabolite concentrations. TPH2 �/� males displayed increased impulsivity and high aggressiveness. TPH2 �/� females displayed greater emotional
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characterization of a functional promoter polymorphism of the human tryptophan hydroxylase 2 gene in serotonergic raphe neurons
Biological Psychiatry, 2007Co-Authors: Kathrin Scheuch, Diego J Walther, Marion Lautenschlager, Maik Grohmann, Silke Stahlberg, Julia Kirchheiner, Peter Zill, Andreas Heinz, Josef PrillerAbstract:Background Tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in brain serotonin (5-HT) biosynthesis. Although dysfunction of 5-HT neurotransmission has been implicated in a variety of neuropsychiatric conditions, the human TPH2 promoter has not been characterized in vitro. Methods The functional relevance of TPH2 promoter polymorphisms was determined with luciferase assays in primary serotonergic neurons from rat raphe nuclei and in human small cell lung carcinoma cells (SHP-77 cells). We also investigated transcription factor binding to the variant promoter sequence with electrophoretic mobility shift assay (EMSA). Results The polymorphism rs11178997 of the human TPH2 promoter significantly reduced TPH2 transcriptional activity by 22% and 7% in primary serotonergic neurons and in SHP-77 cells, respectively. In contrast, no significant differences in promoter activity were observed for the G- and T-alleles of rs4570625. The EMSA revealed reduced binding of the transcription factor POU3F2 (also known as Brn-2, N-Oct-3) to the A-allele of the polymorphism rs11178997. Overexpression of POU3F2 resulted in a robust activation of the TPH2 promoter (2.7-fold). Conclusions Our data suggest that the human TPH2 promoter polymorphism rs11178997 impacts on gene expression, which might have implications for the development and function of the serotonergic system in the brain.
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snp and haplotype analysis of the tryptophan hydroxylase 2 gene in alcohol dependent patients and alcohol related suicide
Neuropsychopharmacology, 2007Co-Authors: Peter Zill, B Bondy, Ulrich W Preuss, G Koller, Michael SoykaAbstract:Several lines of evidence indicate that disturbances of the central serotonergic system are involved in the pathophysiology of alcohol dependence and suicidal behavior. Recent studies have indicated that a newly identified second isoform of the tryptophan hydroxylase gene (TPH2) is preferentially involved in the rate limiting synthesis of neuronal serotonin. Genetic variations in the TPH2 gene have been associated with an increased risk for major depression and suicidal behavior. We performed single SNP (single nucleotide polymorphism), linkage disequilibrium and haplotype studies on 353 alcohol-dependent patients of whom 102 individuals had a history of at least one suicide attempt and 305 healthy controls with 20 SNPs covering the entire gene region of TPH2. Neither single SNP-, nor haplotype analysis could detect significant associations with alcohol dependence and/or suicidal behavior among alcohol-dependent patients. One major haplotype block of strong linkage disequilibrium between introns 5 and 8 of the TPH2 gene has been found in alcoholics and controls, which is in concordance with recent reports. In conclusion, our results suggest that single SNPs, respectively, haplotypes of the TPH2 gene are unlikely to play a major role in the pathophysiology of alcohol dependence or the alcoholism-related phenotype suicidal behavior. Further analysis are needed to confirm these results.
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snp and haplotype analysis of a novel tryptophan hydroxylase isoform TPH2 gene provide evidence for association with major depression
Molecular Psychiatry, 2004Co-Authors: Peter Zill, Thomas C Baghai, Cornelius Schule, Rainer Rupprecht, B Bondy, Peter Zwanzger, Daniela Eser, H J Moller, M AckenheilAbstract:Tryptophan hydroxylase (TPH), being the rate-limiting enzyme in the biosynthesis of serotonin plays a major role as candidate gene in several psychiatric disorders. Recently, a second TPH isoform (TPH2) was identified in mice, which was exclusively present in the brain. In a previous post-mortem study of our own group, we could demonstrate that TPH2 is also expressed in the human brain, but not in peripheral tissues. This is the first report of an association study between polymorphisms in the TPH2 gene and major depression (MD). We performed single-nucleotide polymorphism (SNP), haplotype and linkage disequlibrium studies on 300 depressed patients and 265 healthy controls with 10 SNPs in the TPH2 gene. Significant association was detected between one SNP (P=0.0012, global P=0.0051) and MD. Haplotype analysis produced additional support for association (P<0.0001, global P=0.0001). Our findings provide evidence for an involvement of genetic variants of the TPH2 gene in the pathogenesis of MD and might be a hint on the repeatedly discussed duality of the serotonergic system. These results may open up new research strategies for the analysis of the observed disturbances in the serotonergic system in patients suffering from several other psychiatric disorders.
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single nucleotide polymorphism and haplotype analysis of a novel tryptophan hydroxylase isoform TPH2 gene in suicide victims
Biological Psychiatry, 2004Co-Authors: Peter Zill, Andreas Buttner, Wolfgang Eisenmenger, Hansjurgen Moller, B Bondy, M AckenheilAbstract:Background Tryptophan hydroxylase, the rate-limiting enzyme in the biosynthesis of serotonin, represents a major candidate in numerous genetic association analyses of suicidal behavior; however, the results are so far inconclusive. Recently, a second tryptophan hydroxylase isoform (TPH2) was identified in mice, which was exclusively present in the brain. In a previous postmortem study of our own group, we could demonstrate that TPH2 is also expressed in the human brain but not in peripheral tissues. Methods We performed single nucleotide polymorphisms, haplotypes, and linkage disequilibrium studies on 263 suicide victims and 266 healthy control subjects with 10 single nucleotide polymorphisms in the TPH2 gene. Results Significant association was detected between one single nucleotide polymorphism ( p = .004, global p = .01) and suicide. Additionally, haplotype analysis also produced support for association ( p p = .0001). Conclusions This is the first report about an association between TPH2 gene polymorphisms and completed suicide. Our findings provide evidence for an involvement of genetic variants in the TPH2 gene in suicidal behavior. These results might open up new research strategies for the analysis of the observed disturbances in the serotonergic system in several other psychiatric disorders.
