The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Nenad Blau - One of the best experts on this subject based on the ideXlab platform.
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Clinical Chemistry 47:3 477–485 (2001) Molecular Diagnostics and Genetics Diagnosis of Dopa-responsive Dystonia and Other Tetrahydrobiopterin Disorders by the Study of Biopterin Metabolism in Fibroblasts
2013Co-Authors: Luisa Bonafé, Walter Leimbacher, Beat Thöny, Lucja Kierat, Nenad BlauAbstract:(BH 4) defects are inherited disorders characterized by monoamine neurotransmitter deficiency with decreased activity of one of the BH 4-metabolizing enzymes. The aim of the study was to determine the utility of cultured skin fibroblasts for the diagnosis of these diseases. Methods: Neopterin and biopterin production and GTP cyclohydrolase I (GTPCH) activity were measured in cytokine-stimulated fibroblasts; 6-Pyruvoyltetrahydropterin Synthase (PTPS), sepiapterin reductase (SR), and dihydropteridine reductase (DHPR) activities were measured in unstimulated fibroblasts. We examined 8 patients with DRD, 3 with autosomal recessive GTPCH deficiency, 7 with PTPS deficiency, 3 with DHPR deficiency, and 49 controls (35 fibroblast and 14 amniocyt
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novel mutation affecting the pterin binding site of pts gene and review of pts mutations in thai patients with 6 Pyruvoyltetrahydropterin Synthase deficiency
Journal of Inherited Metabolic Disease, 2009Co-Authors: Nithiwat Vatanavicharn, Nenad Blau, Tze-tze Liu, Kwang-jen Hsiao, C Kuptanon, S Liammongkolkul, P Ratanarak, Pornswan WasantAbstract:Tetrahydrobiopterin (BH4) deficiency comprises heterogeneous disorders resulting in hyperphenylalaninaemia (HPA) and lack of monoamine neurotransmitters. Among these, 6-pyruvoyl-tetrahydropterin Synthase (PTPS) deficiency is the most common disorder. We report a female Thai patient with PTPS deficiency who was initially detected by newborn screening for HPA, and later treated by supplements of BH4, l-dopa/carbidopa, and 5-hydroxytryptophan. Monitoring of serum prolactin representing dopamine sufficiency is used for optimizing the dosage of l-dopa. She showed a remarkable progress of development despite delayed treatment at 5 months of age. Mutation analysis revealed two heterozygous missense mutations of the PTS gene: c.259C>T (p.P87S) inherited from the father; and c.147T>G (p.H49Q) inherited from the mother. The latter is a novel mutation that affects the pterin-binding site of the PTPS enzyme. This novel mutation expands the mutation spectrum of PTPS deficiency. Notably, some PTS mutations have been reported in both Thai and Chinese patients. Whether these common mutations are the result of a founder effect with common ancestors of Thai and Chinese people or intermarriage between Thai and Chinese descents in Thailand remain unclear. In conclusion, severe neurological impairment from BH4 deficiency could be prevented by newborn screening for HPA and proper metabolic management. However, pterin analysis for early diagnosis of BH4 deficiency is still not available in most developing countries.
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Critical Role of Interleukin-1β for Transcriptional Regulation of Endothelial 6-Pyruvoyltetrahydropterin Synthase
Arteriosclerosis thrombosis and vascular biology, 2003Co-Authors: Nicola Franscini, Nenad Blau, Andreas Schaffner, Roland B. Walter, Gabriele SchoedonAbstract:Objective— Synthesis of tetrahydrobiopterin (BH 4 ), an essential cofactor for nitric oxide Synthases, is strongly induced on immunostimulation in vascular endothelial cells (VECs). Expression of GTP cyclohydrolase I (GTPCH), the first enzyme in BH 4 biosynthesis, is regulated by cytokines and considered rate-limiting. Herein we investigated the molecular mechanism and relevance of cytokine-dependent regulation of 6-Pyruvoyltetrahydropterin Synthase (PTPS), the second enzyme in BH 4 synthesis, in human coronary artery endothelial cells (HCAECs). Methods and Results— Real-time polymerase chain reaction revealed a 4-fold induction of PTPS and a 300-fold induction of GTPCH expression by interleukin (IL)-1β/tumor necrosis factor-α/interferon-γ, mainly through de novo transcription. On immunostimulation, PTPS became rate-limiting. Importantly, IL-1β induced PTPS rather than GTPCH. As a result, IL-1β contributed significantly to the amount of BH 4 produced (+40%) but concomitantly reduced the accumulation of the GTPCH intermediate, 7,8-dihydroneopterin triphosphate (−50%). Conclusion— Our data show that PTPS induction is necessary for optimized BH 4 synthesis in cytokine-stimulated HCAECs and point to IL-1β as a leading cytokine in this process.
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Dwarfism and low insulin-like growth factor-1 due to dopamine depletion in Pts-/- mice rescued by feeding neurotransmitter precursors and H4-biopterin.
The Journal of biological chemistry, 2003Co-Authors: Lina Elzaouk, Nenad Blau, Walter Leimbacher, Matteo Turri, Birgit Ledermann, Kurt Bürki, Beat ThönyAbstract:The tetrahydrobiopterin (BH4) cofactor is essential for the biosynthesis of catecholamines and serotonin and for nitric-oxide Synthase (NOS). Alterations in BH4 metabolism are observed in various neurological and psychiatric diseases, and mutations in one of the human metabolic genes causes hyperphenylalaninemia and/or monoamine neurotransmitter deficiency. We report on a knockout mouse for the Pts gene, which codes for a BH4-biosynthetic enzyme. Homozygous Pts / mice developed with normal morphology but died after birth. Upon daily oral administration of BH4 and neurotransmitter precursors the Pts / mice eventually survived. However, at sexual maturity (6 weeks) the mice had only one-third of the normal body weight and were sexually immature. Biochemical analysis revealed no hyperphenylalaninemia, normal brain NOS activity, and almost normal serotonin levels, but brain dopamine was 3% of normal. Low dopamine leads to impaired food consumption as reflected by the severe growth deficiency and a 7-fold reduced serum insulin-like growth factor-1 (IGF1). This is the first link shown between 6-Pyruvoyltetrahydropterin Synthase- or BH4-biosynthetic activity and IGF-1.
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Retrovirus-mediated double transduction of the GTPCH and PTPS genes allows 6-Pyruvoyltetrahydropterin Synthase-deficient human fibroblasts to synthesize and release tetrahydrobiopterin.
Journal of neurochemistry, 2002Co-Authors: Stephanie Laufs, Nenad Blau, Beat ThönyAbstract:The tetrahydrobiopterin (BH 4 ) cofactor is essential for the aromatic amino acid hydroxylases that are involved in phenylalanine degradation and catecholamine and serotonin biosynthesis. Furthermore, BH 4 is an essential and limiting cofactor for all types of nitric oxide Synthases. BH 4 deficiency results in hyperphenylalaninemia and monoamine neurotransmitter depletion associated with progressive mental retardation and is most commonly due to autosomal recessive mutations in 6-Pyruvoyltetrahydropterin Synthase (PTPS), the second enzyme for cofactor biosynthesis. Due to the relatively poor blood-brain barrier penetration of the cofactor, conventional therapy requires, besides oral doses of synthetic BH 4 , administration of neurotransmitter precursors and an aromatic amino acid decarboxylase inhibitor. The outcome of this therapy is not always beneficial. In this study we transduced into primary patient fibroblasts the human cDNAs for the BH 4 biosynthetic enzymes GTP cyclohydrolase I and PTPS, expressed from different retroviral vectors. This allowed BH 4 biosynthesis in originally PTPS-deficient cells. Moreover, the double-transduced fibroblasts released between 200 and 800 pmol of BH 4 / 10 6 cells/day. Such engineered fibroblasts may be grafted into the central nervous system and used as depository cells for constitutive delivery of BH 4 .
Young Shik Park - One of the best experts on this subject based on the ideXlab platform.
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Structural basis of a novel activity of bacterial 6-Pyruvoyltetrahydropterin Synthase homologues distinct from mammalian 6-Pyruvoyltetrahydropterin Synthase activity.
Acta Crystallographica Section D Biological Crystallography, 2014Co-Authors: Kyung Hye Seo, Young Shik Park, Ningning Zhuang, Ki Hun Park, Kon Ho LeeAbstract:Escherichia coli 6-carboxytetrahydropterin Synthase (eCTPS), a homologue of 6-Pyruvoyltetrahydropterin Synthase (PTPS), possesses a much stronger catalytic activity to cleave the side chain of sepiapterin in vitro compared with genuine PTPS activity and catalyzes the conversion of dihydroneopterin triphosphate to 6-carboxy-5,6,7,8-tetrahydropterin in vivo. Crystal structures of wild-type apo eCTPS and of a Cys27Ala mutant eCTPS complexed with sepiapterin have been determined to 2.3 and 2.5 A resolution, respectively. The structures are highly conserved at the active site and the Zn2+ binding site. However, comparison of the eCTPS structures with those of mammalian PTPS homologues revealed that two specific residues, Trp51 and Phe55, that are not found in mammalian PTPS keep the substrate bound by stacking it with their side chains. Replacement of these two residues by site-directed mutagenesis to the residues Met and Leu, which are only found in mammalian PTPS, converted eCTPS to the mammalian PTPS activity. These studies confirm that these two aromatic residues in eCTPS play an essential role in stabilizing the substrate and in the specific enzyme activity that differs from the original PTPS activity. These aromatic residues Trp51 and Phe55 are a key signature of bacterial PTPS enzymes that distinguish them from mammalian PTPS homologues.
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Purification, crystallization and preliminary crystallographic analysis of a 6-Pyruvoyltetrahydropterin Synthase homologue from Esherichia coli.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, 2008Co-Authors: Kyung Hye Seo, Young Shik Park, Che Ok Jeon, Supangat, Hye Lim Kim, Kon Ho LeeAbstract:6-Pyruvoyltetrahydropterin Synthase from E. coli (ePTPS) has been crystallized using the hanging-drop vapour-diffusion method. Hexagonal- and rectangular-shaped crystals were obtained. Diffraction data were collected from the hexagonal and rectangular crystals to 3.0 and 2.3 A resolution, respectively. The hexagonal plate-shaped crystals belonged to space group P321, with unit-cell parameters a = b = 112.59, c = 68.82 A , and contained two molecules in the asymmetric unit. The rectangular crystals belonged to space group I222, with unit-cell parameters a = 112.76, b = 117.66, c = 153.57 A , and contained six molecules in the asymmetric unit. The structure of ePTPS in both crystal forms has been determined by molecular replacement.
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6-Pyruvoyltetrahydropterin Synthase orthologs of either a single or dual domain structure are responsible for tetrahydrobiopterin synthesis in bacteria
FEBS letters, 2006Co-Authors: Jin Sun Kong, Kon Ho Lee, Hye Lim Kim, Ji-youn Kang, O-seob Kwon, Young Shik ParkAbstract:6-Pyruvoyltetrahydropterin Synthase (PTPS) catalyzes the second step of tetrahydrobiopterin (BH4) synthesis. We previously identified PTPS orthologs (bPTPS-Is) in bacteria which do not produce BH4. In this study we disrupted the gene encoding bPTPS-I in Synechococcus sp. PCC 7942, which produces BH4-glucoside. The mutant was normal in BH4-glucoside production, demonstrating that bPTPS-I does not participate in BH4 synthesis in vivo and bringing us a new PTPS ortholog (bPTPS-II) of a bimodular polypeptide. The recombinant Synechococcus bPTPS-II was assayed in vitro to show PTPS activity higher than human enzyme. Further computational analysis revealed the presence of mono and bimodular bPTPS-II orthologs mostly in green sulfur bacteria and cyanobacteria, respectively, which are well known for BH4-glycoside production. In summary we found new bacterial PTPS orthologs, having either a single or dual domain structure and being responsible for BH4 synthesis in vivo, thereby disclosing all the bacterial PTPS homologs.
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Functional role of sepiapterin reductase in the biosynthesis of tetrahydropteridines in Dictyostelium discoideum Ax2
Biochimica et biophysica acta, 2005Co-Authors: Yong Kee Choi, Jin Sun Kong, Young Shik ParkAbstract:In Dictyostelium discoideum Ax2 l-erythro-tetrahydrobiopterin (BH4) is produced in much smaller amount than its stereoisomer d-threo-tetrahydrobiopterin (DH4), both of which are catalyzed by sepiapterin reductase (SR) at the terminal steps. In order to investigate their putative function and biosynthetic regulation, we performed quantitative analysis of not only the intracellular pteridines by HPLC but also the biosynthetic enzymes (GTP cyclohydrolase I, 6-Pyruvoyltetrahydropterin Synthase, SR, and aldose reductase-like enzyme) by Northern blot analysis and activity assay. We found that both SR transcript and activity increased in parallel with a remarkable decline in aldose reductase-like enzyme activity when BH4 increased transiently in the early development. Through in vitro assay of BH4/DH4 synthesis and in vivo rescue experiment of SR knockout mutant, we demonstrated that Dictyostelium SR favors DH4 synthesis while human SR does BH4 synthesis. The results suggest that Dictyostelium SR prefers 1'-oxo-2'-d-hydroxypropyl-tetrahydropterin to 6-Pyruvoyltetrahydropterin as a substrate, thereby maintaining dominant production of DH4 over BH4 in sufficient supply of AR-like enzyme, while allowing increase of BH4 when SR prevails quantitatively over aldose reductase-like enzyme. On the other hand, a transient increase of BH4 may imply that BH4 has an independent function from DH4 in Dictyostelium.
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Escherichia coli 6-Pyruvoyltetrahydropterin Synthase ortholog encoded by ygcM has a new catalytic activity for conversion of sepiapterin to 7,8-dihydropterin.
FEBS letters, 2002Co-Authors: Hyun Joo Woo, Jee Yun Kang, Yong Kee Choi, Yoon Kyung Hwang, Yeon Jung Kim, Chun Gyu Kim, Young Shik ParkAbstract:The putative gene (ygcM) of Escherichia coli was verified in vitro to encode the ortholog of 6-Pyruvoyltetrahydropterin Synthase (PTPS). Unexpectedly, the enzyme was found to convert sepiapterin to 7,8-dihydropterin without any cofactors. The enzymatic product 7,8-dihydropterin was identified by HPLC and mass spectrometry analyses, suggesting a novel activity of the enzyme to cleave the C6 side chain of sepiapterin. The optimal activity occurred at pH 6.5-7.0. The reaction rate increased up to 3.2-fold at 60-80 degrees C, reflecting the thermal stability of the enzyme. The reaction required no metal ion and was activated slightly by low concentrations (1-5 mM) of EDTA. The apparent K(m) value for sepiapterin was determined as 0.92 mM and the V(max) value was 151.3 nmol/min/mg. The new catalytic function of E. coli PTPS does not imply any physiological role, because sepiapterin is not an endogenous substrate of the organism. The same activity, however, was also detected in a PTPS ortholog of Synechocystis sp. PCC 6803 but not significant in Drosophila and human enzymes, suggesting that the activity may be prevalent in bacterial PTPS orthologs.
Beat Thöny - One of the best experts on this subject based on the ideXlab platform.
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Clinical Chemistry 47:3 477–485 (2001) Molecular Diagnostics and Genetics Diagnosis of Dopa-responsive Dystonia and Other Tetrahydrobiopterin Disorders by the Study of Biopterin Metabolism in Fibroblasts
2013Co-Authors: Luisa Bonafé, Walter Leimbacher, Beat Thöny, Lucja Kierat, Nenad BlauAbstract:(BH 4) defects are inherited disorders characterized by monoamine neurotransmitter deficiency with decreased activity of one of the BH 4-metabolizing enzymes. The aim of the study was to determine the utility of cultured skin fibroblasts for the diagnosis of these diseases. Methods: Neopterin and biopterin production and GTP cyclohydrolase I (GTPCH) activity were measured in cytokine-stimulated fibroblasts; 6-Pyruvoyltetrahydropterin Synthase (PTPS), sepiapterin reductase (SR), and dihydropteridine reductase (DHPR) activities were measured in unstimulated fibroblasts. We examined 8 patients with DRD, 3 with autosomal recessive GTPCH deficiency, 7 with PTPS deficiency, 3 with DHPR deficiency, and 49 controls (35 fibroblast and 14 amniocyt
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Pseudoexon exclusion by antisense therapy in 6-pyruvoyl-tetrahydropterin Synthase deficiency.
Human mutation, 2011Co-Authors: Sandra Brasil, Belén Pérez, Magdalena Ugarte, Lourdes R. Desviat, Hiu Man Viecelli, David Meili, Anahita Rassi, Beat ThönyAbstract:Antisense oligonucleotide therapy to modulate splicing mutations in inherited diseases is emerging as a treatment option also for metabolic defects. In this article, we report the effect of cellular antisense therapy to suppress pseudoexon activation in primary dermal fibroblasts from patients with mutations in the PTS gene encoding 6-Pyruvoyltetrahydropterin Synthase (PTPS), which leads to tetrahydrobiopterin and monoamine neurotransmitter deficiency. Pathogenic inclusion of SINE or LINE-derived cryptic exons in different PTPS patients due to the intronic mutations c.84-322A>T, c.163 + 695_163 + 751del57, or c.164-712A>T was demonstrated by transcript analysis in fibroblasts and minigene ex vivo assays. Antisense morpholino oligonucleotides (AMOs) directed to the pseudoexons 3' or 5' splice sites were designed with the aim of preventing the pathological pseudoexon inclusion. At the time of AMO transfection, we investigated patients' cells for correct PTS-mRNA splicing and functional recovery of the PTPS protein. Transcriptional profiling after 24 hr posttransfection revealed a dose- and sequence-specific recovery of normal splicing. Furthermore, PTPS enzyme activity in all three patients' fibroblasts and the pterin profile were close to normal values after antisense treatment. Our results demonstrate proof-of-concept for pseudoexon exclusion therapy using AMO in inherited metabolic disease. Hum Mutat 32:1-9, 2011. © 2011 Wiley-Liss, Inc.
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Dwarfism and low insulin-like growth factor-1 due to dopamine depletion in Pts-/- mice rescued by feeding neurotransmitter precursors and H4-biopterin.
The Journal of biological chemistry, 2003Co-Authors: Lina Elzaouk, Nenad Blau, Walter Leimbacher, Matteo Turri, Birgit Ledermann, Kurt Bürki, Beat ThönyAbstract:The tetrahydrobiopterin (BH4) cofactor is essential for the biosynthesis of catecholamines and serotonin and for nitric-oxide Synthase (NOS). Alterations in BH4 metabolism are observed in various neurological and psychiatric diseases, and mutations in one of the human metabolic genes causes hyperphenylalaninemia and/or monoamine neurotransmitter deficiency. We report on a knockout mouse for the Pts gene, which codes for a BH4-biosynthetic enzyme. Homozygous Pts / mice developed with normal morphology but died after birth. Upon daily oral administration of BH4 and neurotransmitter precursors the Pts / mice eventually survived. However, at sexual maturity (6 weeks) the mice had only one-third of the normal body weight and were sexually immature. Biochemical analysis revealed no hyperphenylalaninemia, normal brain NOS activity, and almost normal serotonin levels, but brain dopamine was 3% of normal. Low dopamine leads to impaired food consumption as reflected by the severe growth deficiency and a 7-fold reduced serum insulin-like growth factor-1 (IGF1). This is the first link shown between 6-Pyruvoyltetrahydropterin Synthase- or BH4-biosynthetic activity and IGF-1.
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Retrovirus-mediated double transduction of the GTPCH and PTPS genes allows 6-Pyruvoyltetrahydropterin Synthase-deficient human fibroblasts to synthesize and release tetrahydrobiopterin.
Journal of neurochemistry, 2002Co-Authors: Stephanie Laufs, Nenad Blau, Beat ThönyAbstract:The tetrahydrobiopterin (BH 4 ) cofactor is essential for the aromatic amino acid hydroxylases that are involved in phenylalanine degradation and catecholamine and serotonin biosynthesis. Furthermore, BH 4 is an essential and limiting cofactor for all types of nitric oxide Synthases. BH 4 deficiency results in hyperphenylalaninemia and monoamine neurotransmitter depletion associated with progressive mental retardation and is most commonly due to autosomal recessive mutations in 6-Pyruvoyltetrahydropterin Synthase (PTPS), the second enzyme for cofactor biosynthesis. Due to the relatively poor blood-brain barrier penetration of the cofactor, conventional therapy requires, besides oral doses of synthetic BH 4 , administration of neurotransmitter precursors and an aromatic amino acid decarboxylase inhibitor. The outcome of this therapy is not always beneficial. In this study we transduced into primary patient fibroblasts the human cDNAs for the BH 4 biosynthetic enzymes GTP cyclohydrolase I and PTPS, expressed from different retroviral vectors. This allowed BH 4 biosynthesis in originally PTPS-deficient cells. Moreover, the double-transduced fibroblasts released between 200 and 800 pmol of BH 4 / 10 6 cells/day. Such engineered fibroblasts may be grafted into the central nervous system and used as depository cells for constitutive delivery of BH 4 .
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Diagnosis of Dopa-responsive Dystonia and Other Tetrahydrobiopterin Disorders by the Study of Biopterin Metabolism in Fibroblasts
Clinical chemistry, 2001Co-Authors: Luisa Bonafé, Walter Leimbacher, Beat Thöny, Lucja Kierat, Nenad BlauAbstract:Background: Dopa-responsive dystonia (DRD) and tetrahydrobiopterin (BH4) defects are inherited disorders characterized by monoamine neurotransmitter deficiency with decreased activity of one of the BH4-metabolizing enzymes. The aim of the study was to determine the utility of cultured skin fibroblasts for the diagnosis of these diseases. Methods: Neopterin and biopterin production and GTP cyclohydrolase I (GTPCH) activity were measured in cytokine-stimulated fibroblasts; 6-Pyruvoyltetrahydropterin Synthase (PTPS), sepiapterin reductase (SR), and dihydropteridine reductase (DHPR) activities were measured in unstimulated fibroblasts. We examined 8 patients with DRD, 3 with autosomal recessive GTPCH deficiency, 7 with PTPS deficiency, 3 with DHPR deficiency, and 49 controls (35 fibroblast and 14 amniocyte samples). Results: Fibroblasts from patients with DRD and autosomal recessive GTPCH deficiency showed reduced GTPCH activity (15.4% and 30.7% of normal activity, respectively) compared with controls ( P
Takahide Nomura - One of the best experts on this subject based on the ideXlab platform.
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Partial Biopterin Deficiency Disturbs Postnatal Development of the Dopaminergic System in the Brain
The Journal of biological chemistry, 2010Co-Authors: Daigo Homma, Chiho Sumi-ichinose, Takahide Nomura, Kazuhisa Ikemoto, Kazunao Kondo, Hirofumi Tokuoka, Setsuko Katoh, Hiroshi IchinoseAbstract:Postnatal development of dopaminergic system is closely related to the development of psychomotor function. Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the biosynthesis of dopamine and requires tetrahydrobiopterin (BH4) as a cofactor. To clarify the effect of partial BH4 deficiency on postnatal development of the dopaminergic system, we examined two lines of mutant mice lacking a BH4-biosynthesizing enzyme, including sepiapterin reductase knock-out (Spr−/−) mice and genetically rescued 6-Pyruvoyltetrahydropterin Synthase knock-out (DPS-Pts−/−) mice. We found that biopterin contents in the brains of these knock-out mice were moderately decreased from postnatal day 0 (P0) and remained constant up to P21. In contrast, the effects of BH4 deficiency on dopamine and TH protein levels were more manifested during the postnatal development. Both of dopamine and TH protein levels were greatly increased from P0 to P21 in wild-type mice but not in those mutant mice. Serotonin levels in those mutant mice were also severely suppressed after P7. Moreover, striatal TH immunoreactivity in Spr−/− mice showed a drop in the late developmental stage, when those mice exhibited hind-limb clasping behavior, a type of motor dysfunction. Our results demonstrate a critical role of biopterin in the augmentation of TH protein in the postnatal period. The developmental manifestation of psychomotor symptoms in BH4 deficiency might be attributable at least partially to high dependence of dopaminergic development on BH4 availability.
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Advanced research on dopamine signaling to develop drugs for the treatment of mental disorders: regulation of dopaminergic neural transmission by tyrosine hydroxylase protein at nerve terminals.
Journal of pharmacological sciences, 2010Co-Authors: Chiho Sumi-ichinose, Takahide Nomura, Hiroshi Ichinose, Kazuhisa Ikemoto, Kazunao KondoAbstract:5R-L-Erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) is an essential cofactor for tyrosine hydroxylase (TH). Recently, a type of dopa-responsive dystonia (DRD) (DYT5, Segawa's disease) was revealed to be caused by dominant mutations of the gene encoding GTP cyclohydrolase I (GCHI), which is the rate-limiting enzyme of BH(4) biosynthesis. In order to probe the role of BH(4) in vivo, we established BH(4)-depleted mice by disrupting the 6-Pyruvoyltetrahydropterin Synthase (PTS) gene (Pts(-/-)) and rescued them by introducing human PTS cDNA under the control of the human dopamine β-hydroxylase (DBH) promoter (Pts(-/-)-DPS). The Pts(-/-)-DPS mice developed hyperphenylalaninemia. Interestingly, tyrosine hydroxylase protein was dramatically reduced in the dopaminergic nerve terminals of these mice, and they developed abnormal posture and motor disturbance. We propose that the biochemical and pathologic changes of Pts(-/-)-DPS mice are caused by mechanisms common to human DRD, and understanding these mechanisms could give us insight into other movement disorders.
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Genetically rescued tetrahydrobiopterin-depleted mice survive with hyperphenylalaninemia and region-specific monoaminergic abnormalities.
Journal of neurochemistry, 2005Co-Authors: Chiho Sumi-ichinose, Fumi Urano, Hiroaki Shiraishi, Hiroshi Ichinose, Kazuhisa Ikemoto, Atsushi Shimomura, Takashi Sato, Takao Senda, Takahide NomuraAbstract:One of the possibly mutated genes in DOPA-responsive dystonia (DRD, Segawa's disease) is the gene encoding GTP cyclohydrolase I, which is the rate-limiting enzyme for tetrahydrobiopterin (BH4) biosynthesis. Based on our findings on 6-Pyruvoyltetrahydropterin Synthase (PTS) gene-disrupted (Pts–/–) mice, we suggested that the amount of tyrosine hydroxylase (TH) protein in dopaminergic nerve terminals is regulated by the intracellular concentration of BH4. In this present work, we rescued Pts–/– mice by transgenic introduction of human PTS cDNA under the control of the dopamine β-hydroxylase promoter to examine regional differences in the sensitivity of dopaminergic neurons to BH4-insufficiency. The DPS-rescued (Pts–/–, DPS) mice showed severe hyperphenylalaninemia. Human PTS was efficiently expressed in noradrenergic regions but only in a small number of dopaminergic neurons. Biopterin and dopamine contents, and TH activity in the striatum were poorly restored compared with those in the midbrain. TH-immunoreactivity in the lateral region of the striatum was far weaker than that in the medial region or in the nucleus accumbens. We concluded that dopaminergic nerve terminals projecting to the lateral region of the striatum are the most sensitive to BH4-insufficiency. Biochemical and pathological changes in DPS-rescued mice were similar to those in human malignant hyperphenylalaninemia and DRD.
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Catecholamines and serotonin are differently regulated by tetrahydrobiopterin. A study from 6-Pyruvoyltetrahydropterin Synthase knockout mice.
The Journal of biological chemistry, 2001Co-Authors: Chiho Sumi-ichinose, Fumi Urano, Risa Kuroda, Tamae Ohye, Masayo Kojima, Masahiro Tazawa, Hiroaki Shiraishi, Yasumichi Hagino, Toshiharu Nagatsu, Takahide NomuraAbstract:(6R)-L-erythro-5,6,7,8-Tetrahydrobiopterin (BH4) is an essential cofactor for tyrosine hydroxylase (TH), tryptophan hydroxylase, phenylalanine hydroxylase, and nitric-oxide Synthase. These enzymes synthesize neurotransmitters, e.g. catecholamines, serotonin, and nitric oxide (NO). We established mice unable to synthesize BH4 by disruption of the 6-Pyruvoyltetrahydropterin Synthase gene, the encoded protein of which catalyzes the second step of BH4 biosynthesis. Homozygous mice were born at the almost expected Mendelian ratio, but died within 48 h after birth. In the brain of homozygous mutant neonates, levels of biopterin, catecholamines, and serotonin were extremely low. The number of TH molecules was highly dependent on the intracellular concentration of BH4 at nerve terminals. Alteration of the TH protein level by modulation of the BH4 content is a novel regulatory mechanism. Our data showing that catecholaminergic, serotonergic, and NO systems were differently affected by BH4 starvation suggest the possible involvement of BH4 synthesis in the etiology of monoamine-based neurological and neuropsychiatric disorders.
H Wachter - One of the best experts on this subject based on the ideXlab platform.
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Determination of tetrahydrobiopterin biosynthetic activities by high-performance liquid chromatography with fluorescence detection
Methods in Enzymology, 1997Co-Authors: E R Werner, H Wachter, Gabriele Werner-felmayerAbstract:Publisher Summary Tetrahydrobiopterin serves as cofactor of phenylalanine 4-monooxygenase, tyrosine 3-monooxygenase, glyceryl-ether monooxygenase, and nitric oxide Synthase. Because intracellular tetrahydrobiopterin concentrations affect the amount of metabolites of, for example, nitric oxide Synthase formed by intact cells, regulation of the biosynthesis of tetrahydrobiopterin is of interest. This chapter discusses assays of the three biosynthetic enzymes involved in the formation of tetrahydrobiopterin from guanosine 5'-triphospate (GTP) based on highperformance liquid chromatography (HPLC) with fluorescence detection. While the assay of GTP cyclohydrolase I, the first enzyme of the pathway that is regulated by cytokines, as well as the assay for sepiapterin reductase, can be run with materials that are commercially available, 6-Pyruvoyltetrahydropterin Synthase assays are performed with two purified enzymes, GTP cyclohydrolase I and sepiapterin reductase, to synthesize the labile substrate and to help convert the unstable product to a stable metabolite.
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Impact of tumour necrosis factor-α and interferon-γ on tetrahydrobiopterin synthesis in murine fibroblasts and macrophages
Biochemical Journal, 1991Co-Authors: E R Werner, Gabriele Werner-felmayer, Arno Hausen, J.j. Yim, D. Fuchs, Gilbert Reibnegger, H WachterAbstract:Tumour necrosis factor-alpha causes an up to 30-fold induction of GTP cyclohydrolase I (EC 3.5.4.16) activity in murine dermal fibroblasts in a dose-dependent manner. Owing to the high constitutive activities of 6-Pyruvoyltetrahydropterin Synthase and sepiapterin reductase (EC 1.1.1.153), this potentiates biosynthesis of tetrahydrobiopterin. Murine macrophages already contain high activities of GTP cyclohydrolase I when unstimulated, and this is further augmented up to 4-fold by tumour necrosis factor-alpha/interferon-gamma. In Western blots an antiserum to murine liver GTP cyclohydrolase I does not stain cell extracts with high enzyme activities, suggesting that the cytokine induced peripheral form of GTP cyclohydrolase I might differ from the liver form.
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Impact of tumour necrosis factor-alpha and interferon-gamma on tetrahydrobiopterin synthesis in murine fibroblasts and macrophages.
The Biochemical journal, 1991Co-Authors: E R Werner, Gabriele Werner-felmayer, J.j. Yim, D. Fuchs, Gilbert Reibnegger, A Hausen, H WachterAbstract:Tumour necrosis factor-alpha causes an up to 30-fold induction of GTP cyclohydrolase I (EC 3.5.4.16) activity in murine dermal fibroblasts in a dose-dependent manner. Owing to the high constitutive activities of 6-Pyruvoyltetrahydropterin Synthase and sepiapterin reductase (EC 1.1.1.153), this potentiates biosynthesis of tetrahydrobiopterin. Murine macrophages already contain high activities of GTP cyclohydrolase I when unstimulated, and this is further augmented up to 4-fold by tumour necrosis factor-alpha/interferon-gamma. In Western blots an antiserum to murine liver GTP cyclohydrolase I does not stain cell extracts with high enzyme activities, suggesting that the cytokine induced peripheral form of GTP cyclohydrolase I might differ from the liver form.
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Biochemistry and function of pteridine synthesis in human and murine macrophages.
Pathobiology : journal of immunopathology molecular and cellular biology, 1991Co-Authors: Ernst R. Werner, Gabriele Werner-felmayer, Dietmar Fuchs, Arno Hausen, R. Reibnegger, J.j. Yim, H WachterAbstract:We investigated intracellular pteridine concentrations, activities of pteridine biosynthetic enzymes and formation of nitrogen oxides from arginine in human peripheral-blood-derived macrophages and in myelomonocytoma (THP-1) cells, as well as in murine peritoneal and spleen-derived macrophages and in murine macrophage lines (P388-D1, J774-A.1). Interferon-γ (IFN-γ) induces the activity of GTP-cyclohydrolase I up to 40-fold in human cells. In human macrophages and THP-1 cells, this induced activity is higher than the constitutively present activity of the subsequent enzyme, the 6-Pyruvoyltetrahydropterin Synthase. As a consequence, large amounts of neopterin are formed during IFN-γ-triggered synthesis of tetrahydrobiopterin. Murine macrophages constitutively synthesize tetrahydrobiopterin. The activity of GTP-cyclohydrolase I remains unchanged by treatment with IFN-γ or tumor necrosis factor-α. This activity is lower than the subsequent 6-Pyruvoyltetrahydropterin Synthase activity, thus explaining the lack of neopterin in murine cells, tissues and body fluids. Inhibition and reconstitution of pteridine synthesis in activated murine macrophages by specific drugs demonstrate that tetrahydrobiopterin regulates the amount of nitrogen oxides formed from arginine in intact cells, thus providing a rationale for therapeutic intervention.
