Tetrahydrobiopterin (BH4) is an essential cofactor for all three nitric oxide synthase (NOS isoforms), which plays an important role in vascular diseases. GTP cyclohydrolase 1 (GCH 1) is the first-step and rate-limiting enzyme for BH4 biosynthesis in its de novo pathway. Common GCH1 gene variant C+243T in the 3'-untranslated region predicts NO excretion. The present study examined the predictive role of GCH 1 gene 3'-UTR C+243T variant in the long-term outcome of ischemic stroke. A total of 142 patients with first-onset ischemic stroke were recruited and detected for genotype of GCH1 3'-UTR C+243T by a TaqMan SNP Genotyping assay. Subsequent vascular events and death were determined over a 5-year follow-up period. The frequency of GCH1 3'-UTR +243 C/T or T/T genotype was significantly increased in patients with endpoint events as compared with those without events (74% vs 57.8%, P=0.06). Cox regression survival analysis indicated that an increased probability of death or new vascular events was found in patients with GCH1 3'-UTR +243 C/T or T/T genotype compared with those with GCH1 3'-UTR C/C genotype (40.6% vs 25.5%), GCH1 3'-UTR +243 C/T or T/T genotype relative to GCH1 3'-UTR C/C genotype was associated with the increased risk of death or vascular events even after adjustment for other risk factors (OR=2.171, 95% CI: 1.066-4.424, P=0.033). It was concluded that GCH1 3'-UTR C+243T variant was an independent predictor of worsening long-term outcomes in patients with first-onset ischemic stroke.
3' Untranslated Regions ; genetics ; Aged ; Brain Ischemia ; genetics ; Female ; GTP Cyclohydrolase ; genetics ; Humans ; Male ; Middle Aged ; Nitric Oxide ; metabolism ; Prognosis ; Risk Factors ; Stroke ; diagnosis ; genetics

OBJECTIVETo study the incidence of various enzyme deficiency in tetrahydrobiopterin (BH4) metabolism and the related gene mutation among the patients with motor disturbance and mental retardation.

METHODSOne hundred patients with unknown motor disturbance and mental retardation were referred to this study. All patients were performed by phenylalanine (Phe) and BH4 loading test, urinary pterin analysis and dihydropteridine reductase (DHPR) activity. Some patients received the dopa treatment for diagnosis of dopa-responsive dystonia (DRD). The analysis of GTP cyclohydrolase 1 gene (GCH1) mutation for DRD patients and the analysis of 6-pyruvoyl tetrahydropterin synthase (PTS) gene mutations for PTS deficient patients were done under the consent from their parents.

RESULTSSeventy of 100 patients had normal basic blood Phe levels, six (6%) patients were diagnosed as DRD. Thirty patients had hyperphenylalaninemia (HPA), eight (8%) were diagnosed as PTS deficiency and 22(22%) were diagnosed as phenylalanine hydroxylase (PAH) deficiency. All patients had normal DHPR activity. The mutation IVS5+3insT of GCH1 was found in 2 patients with DRD. Seven kinds of PTS mutations were found in 8 patients with PTS deficiency, and 75% of the mutations were 259C-->T,286G-->A and 155A-->G.

CONCLUSIONSome patients with unknown motor disturbance and mental retardation may suffer from BH4 metabolism related diseases. Theses patients are necessary to be screened for such kind of diseases in order to confirm the diagnosis.

Adolescent ; Biopterin ; analogs & derivatives ; metabolism ; Child ; Child, Preschool ; Dihydropteridine Reductase ; genetics ; metabolism ; Dystonia ; genetics ; metabolism ; Female ; GTP Cyclohydrolase ; genetics ; metabolism ; Humans ; Infant ; Intellectual Disability ; genetics ; metabolism ; Male ; Mutation ; Phenylalanine Hydroxylase ; genetics ; metabolism ; Phosphorus-Oxygen Lyases ; genetics ; metabolism

Most attempts at rational development of new analgesics have failed, in part because chronic pain involves multiple processes that remain poorly understood. To improve translational success, one strategy is to select novel targets for which there is proof of clinical relevance, either genetically through heritable traits, or pharmacologically. Such an approach by definition yields targets with high clinical validity. The biology of these targets can be elucidated in animal models before returning to the patients with a refined therapeutic. For optimal treatment, having biomarkers of drug action available is also a plus. Here we describe a case study in rational drug design: the use of controlled inhibition of peripheral tetrahydrobiopterin (BH4) synthesis to reduce abnormal chronic pain states without altering nociceptive-protective pain. Initially identified in a population of patients with low back pain, the association between BH4 production and chronic pain has been confirmed in more than 12 independent cohorts, through a common haplotype (present in 25% of Caucasians) of the rate-limiting enzyme for BH4 synthesis, GTP cyclohydrolase 1 (GCH1). Genetic tools in mice have demonstrated that both injured sensory neurons and activated macrophages engage increased BH4 synthesis to cause chronic pain. GCH1 is an obligate enzyme for de novo BH4 production. Therefore, inhibiting GCH1 activity eliminates all BH4 production, affecting the synthesis of multiple neurotransmitters and signaling molecules and interfering with physiological function. In contrast, targeting the last enzyme of the BH4 synthesis pathway, sepiapterin reductase (SPR), allows reduction of pathological BH4 production without completely blocking physiological BH4 synthesis. Systemic SPR inhibition in mice has not revealed any safety concerns to date, and available genetic and pharmacologic data suggest similar responses in humans. Finally, because it is present in vivo only when SPR is inhibited, sepiapterin serves as a reliable biomarker of target engagement, allowing potential quantification of drug efficacy. The emerging development of therapeutics that target BH4 synthesis to treat chronic pain illustrates the power of combining human and mouse genetics: human genetic studies for clinical selection of relevant targets, coupled with causality studies in mice, allowing the rational engineering of new analgesics.
Analgesics ; therapeutic use ; Animals ; Biopterin ; analogs & derivatives ; metabolism ; Chronic Pain ; drug therapy ; genetics ; Disease Models, Animal ; Drug Discovery ; GTP Cyclohydrolase ; genetics ; metabolism ; Humans ; Rodentia ; Signal Transduction ; drug effects ; genetics

Recently it was shown that single nucleotide polymorphisms (SNPs) can explain individual variation because of the small changes of the gene expression level and that the 50% decreased expression of an allele might even lead to predisposition to cancer. In this study, we found that a decreased expression of an allele might cause predisposition to genetic disease. Dopa responsive dystonia (DRD) is a dominant disease caused by mutations in GCH1 gene. The sequence analysis of the GCH1 in a patient with typical DRD symptoms revealed two novel missense mutations instead of a single dominant mutation. Family members with either of the mutations did not have any symptoms of DRD. The expression level of a R198W mutant allele decreased to about 50%, suggesting that modestly decreased expression caused by an SNP should lead to predisposition of a genetic disease in susceptible individuals.
Child ; Clubfoot/genetics ; Dopamine/deficiency ; Dystonic Disorders/drug therapy/enzymology/*genetics/physiopathology ; GTP Cyclohydrolase/*genetics/metabolism ; Genes, Recessive ; *Genetic Predisposition to Disease ; Humans ; Levodopa/administration & dosage ; Male ; Mutation, Missense ; Pedigree ; Polymorphism, Genetic

OBJECTIVETo investigate the protective effect and its underlying mechanism of 2,4-diamino-6-hydroxy-pyrimidine (DAHP), an inhibitor of GTP-cyclohydrolase I (GTP-CHI), on postburn Staphylococcus aureus (S. aureus) sepsis in rats.

METHODSFifty-six Wistar rats were randomly divided into four groups, i.e. normal control, scalding control, postburn sepsis group and DAHP treatment group. Tissue samples from liver, kidneys, lungs and heart were aseptically taken, and in which the GTP-CHI and inducible nitric oxide synthase (iNOS) contents and the mRNA expression of tumor necrosis factor-alpha (TNFalpha) were determined. Furthermore, biopterin (BH(4)) and nitric oxide (NO) levels in these tissue were also measured.

RESULTSAfter the scalding injury followed by bacterial challenge, the GTP-CHI gene expression and biopterin levels were significantly increased in all tissue sampled, and so were iNOS mRNA expression and NO (P < 0.01), especially in liver and lungs. The expressions of GTP-CHI mRNA and iNOS mRNA and the production of BH(4) and NO in all tissue were evidently inhibited by the pretreatment with DAHP (P < 0.05 approximately 0.01). At the same time, the TNFalpha expression was also obviously decreased. In addition, The mortality at 6 hr in rats of DAHP treatment group was decreased.

CONCLUSIONThe prognosis of the scalding rats complicated by sepsis caused by G(+) bacteria could be improved by DAHP pretreatment, which might be related to the inhibition of the production of BH(4) and NO by DAHP.

Animals ; Biopterin ; metabolism ; Burns ; complications ; genetics ; metabolism ; Enzyme Inhibitors ; pharmacology ; GTP Cyclohydrolase ; antagonists & inhibitors ; genetics ; Gene Expression Regulation ; drug effects ; Heart ; drug effects ; Hypoxanthines ; pharmacology ; Kidney ; drug effects ; metabolism ; Liver ; drug effects ; metabolism ; Lung ; drug effects ; metabolism ; Male ; Myocardium ; metabolism ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; genetics ; RNA, Messenger ; drug effects ; genetics ; metabolism ; Rats ; Rats, Wistar ; Sepsis ; etiology ; prevention & control ; Staphylococcal Infections ; etiology ; prevention & control ; Staphylococcus aureus ; drug effects ; growth & development ; Sugar Acids ; Time Factors ; Tumor Necrosis Factor-alpha ; genetics

OBJECTIVETo observe the influence of treatment with the inhibitor of extracellular-signal regulated protein kinase (ERK) signal transduction pathway on the expression of biopterin/nitric oxide (NO) as well as the activation of nuclear factor-kappaB (NF-kappaB), and to clarify the potential cross-talk regulation mechanisms between ERK and NF-kappaB pathway in biopterin-mediated NO induction in rats with endotoxic shock.

METHODSUsing an endotoxic shock model, 60 male Wistar rats were randomly divided into normal controls (n = 8), endotoxic shock group (n = 32) and PD98059 treatment group (n = 20). At serial time points animals in each group were sacrificed, and tissue samples from liver, lungs as well as kidneys were harvested to detect NF-kappaB activity, guanosine triphosphate-cyclohydrolase (GTP-CHI) and inducible nitric oxide synthase (iNOS) mRNA expression. Biopterin and NO levels in plasma and tissues were also assayed.

RESULTSIt was found that after lipopolysaccharide (LPS) challenge, GTP-CHI mRNA expression and biopterin levels significantly elevated in liver, lungs and kidneys, keeping at high values up to 24 h, so did the values of iNOS mRNA expression and NO levels. NF-kappaB DNA binding activity was enhanced rapidly in various tissues, peaking at 2 h after LPS challenge. Treatment with PD98059, an inhibitor of ERK signal transduction pathway, could significantly inhibit GTP-CHI mRNA expression in kidneys, and GTP-CHI mRNA expression in liver and lungs showed certain down-regulation tendency. At the same time, biopterin level was significantly decreased in plasma, liver and kidneys at 12 h. Similarly, iNOS/NO induction at early stage markedly decreased in various tissues. In addition, treatment with PD98059 reduced NF-kappaB DNA binding activity in liver, lungs, as well as kidneys at 2-6 h, 2 h, 24 h and 24 h after LPS challenge, respectively.

CONCLUSIONSInhibition of ERK pathway could partially inhibit the production of biopterin/NO as well as the activation of NF-kappaB pathway, which indicated that cross-talk regulation seems to be existed between ERK and NF-kappaB pathway, and they might be involved in the regulatory process of biopterin-mediated nitric oxide induction in rats with endotoxic shock.

Animals ; Biopterin ; metabolism ; physiology ; Disease Models, Animal ; Extracellular Signal-Regulated MAP Kinases ; physiology ; GTP Cyclohydrolase ; biosynthesis ; genetics ; Male ; NF-kappa B ; metabolism ; Nitric Oxide ; biosynthesis ; Nitric Oxide Synthase Type II ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Wistar ; Shock, Septic ; physiopathology ; Signal Transduction