Hydroxylase Gene (hydroxylase + gene)

Distribution by Scientific Domains

Selected Abstracts

A Functional Polymorphism in the Promoter Region of the Tryptophan Hydroxylase Gene Is Associated With Alcohol Dependence in One Aboriginal Group in Taiwan

ALCOHOLISM, Issue 1 2005
H Sunny Sun
Background: Polymorphisms within intron 7 of the tryptophan hydroxylase (TPH1) gene were found to be associated with alcohol dependence in different ethnic groups, including the aboriginal Bunun group in Taiwan. This study aimed to identify genetic variants at the TPH1 locus and to examine their associations with alcoholism. We hypothesized that the polymorphism of TPH1 gene is functional and influences the human circadian rhythm to contribute to the pathophysiology of alcohol dependence. Methods: DNA from the Taiwanese Han and Bunun was subjected to sequence for screening genetic variation in the coding and promoter regions of the TPH1 locus. Polymorphisms among individuals with alcohol dependence and control subjects in two ethnic groups in Taiwan were investigated. Results: Three variants in the TPH1 promoter region were identified, and the markers are in complete linkage disequilibrium in both populations. Positive associations at both allelic and genotypic levels were obtained between case and control groups in the Bunun. Expression studies demonstrated that the variants indeed affected reporter gene activity in human choriocarcinoma and colon adenocarcinoma cell lines. Conclusions: Polymorphisms in the promoter region may influence the function of the TPH1 gene and further influence the proclivity of alcohol dependence in one ethnic group in Taiwan. The associations between TPH1 genotypes and alcoholism may deserve further investigation. [source]

Four novel mutations in the Tyrosine Hydroxylase gene in patients with infantile parkinsonism

Mutation detection in the Tyrosine Hydroxylase gene (TH) was performed in patients from two families. DNA sequencing revealed the presence of four novel missense mutations (exon 9 and 14 in family A, exon 8 and 9 in family B); the mutations were confirmed with restriction enzyme analysis, and did not occur in control alleles. Three mutations are in the catalytic domain of the enzyme and one may disturb tetramerization. At the moment, all patients are in the fourth decade of life. For more than 30 years they have been able to live a normal life with low-dose l -DOPA medication. [source]

Dopamine and sensory tissue development in Drosophila melanogaster

Wendi Neckameyer
Abstract Dopamine is an important signaling molecule in the nervous system; it also plays a vital role in the development of diverse non-neuronal tissues in the fruit fly Drosophila melanogaster. The current study demonstrates that males depleted of dopamine as third instar larvae (via inhibition of the biosynthetic enzyme tyrosine hydroxylase) demonstrated abnormalities in courtship behavior as adults. These defects were suggestive of abnormalities in sensory perception and/or processing. Electroretinograms (ERGs) of eyes from adults depleted of dopamine for 1 day as third instar larvae revealed diminished or absent on- and off-transients. These sensory defects were rescued by the addition of L -DOPA in conjunction with tyrosine hydroxylase inhibition during the larval stage. Depletion of dopamine in the first or second larval instar was lethal, but this was not due to a general inhibition of proliferative cells. To establish that dopamine was synthesized in tissues destined to become part of the adult sensory apparatus, transgenic lines were generated containing 1 or 4 kb of 5, upstream sequences from the Drosophila tyrosine hydroxylase gene (DTH) fused to the E. coli ,-galactosidase reporter. The DTH promoters directed expression of the reporter gene in discrete and consistent patterns within the imaginal discs, in addition to the expected expression in gonadal, brain, and cuticular tissues. The ,-galactosidase expression colocalized with tyrosine hydroxylase protein. These results are consistent with a developmental requirement for dopamine in the normal physiology of adult sensory tissues. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 280,294, 2001 [source]

Low frequency of Parkin, Tyrosine Hydroxylase, and GTP Cyclohydrolase I gene mutations in a Danish population of early-onset Parkinson's Disease

J. M. Hertz
Autosomal recessive Parkinson's disease (PD) with early-onset may be caused by mutations in the parkin gene (PARK2). We have ascertained 87 Danish patients with an early-onset form of PD (age at onset ,40 years, or ,50 years if family history is positive) in a multicenter study in order to determine the frequency of PARK2 mutations. Analysis of the GTP cyclohydrolase I gene (GCH1) and the tyrosine hydroxylase gene (TH), mutated in dopa-responsive dystonia and juvenile PD, have also been included. Ten different PARK2 mutations were identified in 10 patients. Two of the patients (2.3%) were found to have homozygous or compound heterozygous mutations, and eight of the patients (9.2%) were found to be heterozygous. A mutation has been identified in 10.4% of the sporadic cases and in 15.0% of cases with a positive family history of PD. One patient was found to be heterozygous for both a PARK2 mutation and a missense mutation (A6T) in TH of unknown significance. It cannot be excluded that both mutations contribute to the phenotype. No other putative disease causing TH or GCH1 mutations were found. In conclusion, homozygous, or compound heterozygous PARK2 mutations, and mutations in GCH1 and TH, are rare even in a population of PD patients with early-onset of the disease. [source]

Disruption of dopamine homeostasis underlies selective neurodegeneration mediated by ,-synuclein

Soon S. Park
Abstract A key challenge in Parkinson's disease research is to understand mechanisms underlying selective degeneration of dopaminergic neurons mediated by genetic factors such as ,-synuclein (,-Syn). The present study examined whether dopamine (DA)-dependent oxidative stress underlies ,-Syn-mediated neurodegeneration using Drosophila primary neuronal cultures. Green fluorescent protein (GFP) was used to identify live dopaminergic neurons in primary cultures prepared on a marked photoetched coverslip, which allowed us to repeatedly access preidentified dopaminergic neurons at different time points in a non-invasive manner. This live tracking of GFP-marked dopaminergic neurons revealed age-dependent neurodegeneration mediated by a mutant human ,-Syn (A30P). Degeneration was rescued when ,-Syn neuronal cultures were incubated with 1 mm glutathione from Day 3 after culturing. Furthermore, depletion of cytoplasmic DA by 100 µm,-methyl- p -tyrosine completely rescued the early stage of ,-Syn-mediated dopaminergic cell loss, demonstrating that DA plays a major role in oxidative stress-dependent neurodegeneration mediated by ,-Syn. In contrast, overexpression of a Drosophila tyrosine hydroxylase gene (dTH1) alone caused DA neurodegeneration by enhanced DA synthesis in the cytoplasm. Age-dependent dopaminergic cell loss was comparable in ,-Syn vs dTH1-overexpressed neuronal cultures, indicating that increased DA levels in the cytoplasm is a critical change downstream of mutant ,-Syn function. Finally, overexpression of a Drosophila vesicular monoamine transporter rescued ,-Syn-mediated neurodegeneration through enhanced sequestration of cytoplasmic DA into synaptic vesicles, further indicating that a main cause of selective neurodegeneration is ,-Syn-induced disruption of DA homeostasis. All of these results demonstrate that elevated cytoplasmic DA is a main factor underlying the early stage of ,-Syn-mediated neurodegeneration. [source]

The PAH gene, phenylketonuria, and a paradigm shift,,

HUMAN MUTATION, Issue 9 2007
Charles R. Scriver
Abstract "Inborn errors of metabolism," first recognized 100 years ago by Garrod, were seen as transforming evidence for chemical and biological individuality. Phenylketonuria (PKU), a Mendelian autosomal recessive phenotype, was identified in 1934 by Asbjörn Fölling. It is a disease with impaired postnatal cognitive development resulting from a neurotoxic effect of hyperphenylalaninemia (HPA). Its metabolic phenotype is accountable to multifactorial origins both in nurture, where the normal nutritional experience introduces L-phenylalanine, and in nature, where mutations (>500 alleles) occur in the phenylalanine hydroxylase gene (PAH) on chromosome 12q23.2 encoding the L-phenylalanine hydroxylase enzyme (EC The PAH enzyme converts phenylalanine to tyrosine in the presence of molecular oxygen and catalytic amounts of tetrahydrobiopterin (BH4), its nonprotein cofactor. PKU is among the first of the human genetic diseases to enter, through newborn screening, the domain of public health, and to show a treatment effect. This effect caused a paradigm shift in attitudes about genetic disease. The PKU story contains many messages, including: a framework on which to appreciate the complexity of PKU in which phenotype reflects both locus-specific and genomic components; what the human PAH gene tells us about human population genetics and evolution of modern humans; and how our interest in PKU is served by a locus-specific mutation database (http://www.pahdb.mcgill.ca; last accessed 20 March 2007). The individual Mendelian PKU phenotype has no "simple" or single explanation; every patient has her/his own complex PKU phenotype and will be treated accordingly. Knowledge about PKU reveals genomic components of both disease and health. Hum Mutat 28(9), 831,845, 2007. Published 2007 Wiley-Liss, Inc. [source]

Overexpression of c-Fos is sufficient to stimulate tyrosine hydroxylase (TH) gene transcription in rat pheochromocytoma PC18 cells

Baoyong Sun
Abstract The AP1 site within the tyrosine hydroxylase gene proximal promoter is essential for the response of the gene to numerous stimuli. Stimulation of this gene is often associated with induction of the AP1 transcription factor, c-Fos. However, many stimuli activate or induce multiple transcription factors that interact with this AP1 site or other sites within the gene's proximal promoter. Hence, it remains unclear whether c-Fos induction by itself is sufficient to stimulate the tyrosine hydroxylase gene. In this study we produce rat pheochromocytoma PC18 cells that overexpress c-Fos under control of the tet-inducible system. We demonstrate that induction of c-Fos leads to dramatic stimulation of tyrosine hydroxylase gene transcription rate measured using nuclear run-on assays. This stimulation is closely associated quantitatively with the induction of c-Fos and does not apparently require phosphorylation of c-Fos. The response is partially dependent on the AP1 site within the tyrosine hydroxylase proximal promoter. However, the response of the proximal promoter to c-Fos induction is relatively small compared with that of the endogenous gene. Consequently, our results suggest that c-Fos exerts its influence on the tyrosine hydroxylase gene via multiple mechanisms that are dependent and independent of the proximal promoter AP1 site. [source]

Prenatal diagnosis of 21-hydroxylase deficiency caused by gene conversion and rearrangements: pitfalls and molecular diagnostic solutions

Rong Mao
Abstract Objectives The present paper reports the prenatal diagnosis of congenital adrenal hyperplasia (CAH) in two cases of 21-hydroxylase deficiency. DNA diagnostic errors can be caused by the presence of the highly homologous 21-hydroxylase pseudogene, CYP21P, adjacent to the functional gene, CYP21. The present paper details how complex gene conversions and rearrangements between the CYP21 and CYP21P pose unique complications for prenatal diagnosis. Methods Analysis of eight common mutations in the 21-hydroxylase gene as well as deletion of the entire gene is accomplished using polymerase chin reaction (PCR) followed by amplified created restriction site (ACRS) or allele-specific oligohybridization (ASO) and Southern blot followed by hybridization to a CYP21-specific probe. Linkage analysis was performed using microsatellite markers flanking the CYP21 gene. Results The direct mutation detection assay indicated a complicated gene conversion and rearrangement in the probands of both families. Interpretation of these rearrangements made it difficult to determine whether or not the fetuses would be affected with CAH. Linkage studies revealed that each fetus had inherited both parental disease chromosomes and was therefore predicted to be affected with CAH. Conclusion As observed in the two reported cases, direct DNA analysis may provide limited information due to gene conversion or rearrangement between the CYP21 and CYP21P genes. These cases suggest that direct mutation detection should be supported by linkage analysis, whenever possible, to provide more comprehensive information for the family. Copyright © 2002 John Wiley & Sons, Ltd. [source]

The Arabidopsis thaliana TIR-NB-LRR R-protein, RPP1A; protein localization and constitutive activation of defence by truncated alleles in tobacco and Arabidopsis

L. Michael Weaver
Summary Specific recognition of Hyaloperonospora parasitica isolate Cala2 by Arabidopsis thaliana Ws-0 is mediated by the resistance gene RPP1A. Transient expression of different truncations of RPP1A in tobacco leaves revealed that its TIR-NB-ARC portion is sufficient to induce an elicitor-independent cell death. In stable transgenic lines of Arabidopsis, overexpression of the RPP1A TIR-NB-ARC domains (E12) using the 35S promoter leads to broad-spectrum resistance to virulent strains of H. parasitica and Pseudomonas syringae DC3000. The TIR-NB-ARC-mediated constitutive immunity is due to activation of the salicylic acid-dependent resistance pathway and is relieved by either a mutation in EDS1 or the presence of the salicylate hydroxylase gene, NahG. Growth of 35S::E12 plants is reduced, a phenotype observed in many constitutively resistant mutants. RPP1A carries a hydrophobic peptide at its N-terminus that directs the RPP1A protein into membranes, though it may not be the sole determinant mediating membrane association of RPP1A. Two-phase partitioning and sucrose density gradient sedimentation established that RPP1A resides in the endoplasmic reticulum and/or Golgi apparatus. [source]

Mutations in the cyclic adenosine monophosphate response element of the tyrosine hydroxylase gene

Marcel M. Verbeek PhD
Tyrosine hydroxylase (TH) deficiency (OMIM 191290) is one cause of early-onset dopa-responsive dystonia. We describe seven cases from five unrelated families with dopa-responsive dystonia and low homovanillic acid in cerebrospinal fluid who were suspected to suffer from TH deficiency. Analysis of part of the TH promotor showed five homozygous and two heterozygous mutations in the highly conserved cyclic adenosine monophosphate response element. Our data suggest that, if no mutations are found in the coding regions of the gene in patients strongly suspected of TH deficiency, the search for pathogenic mutations should be extended to regulatory promotor elements. Ann Neurol 2007 [source]

A functional polymorphism regulating dopamine ,-hydroxylase influences against Parkinson's disease

Daniel G. Healy MRCPI
A functional ,1021C , T polymorphism in the dopamine ,-hydroxylase gene has been demonstrated to regulate plasma DBH activity. We report that individuals with genetically determined low serum DBH activity (genotype T/T) have protection against Parkinson's disease (p = 0.01). In particular, we observed an underrepresentation of the T/T genotype odds ratio = 0.46 (CI = 0.27-0.8). Rather than identifying a haplotype, or a marker in linkage disequilibrium with the risk variant, this to our knowledge is the first report directly linking PD susceptibility with a proven functional variant. Ann Neurol 2004 [source]

cDNA cloning and induction of tyrosine hydroxylase gene from the diamondback moth, Plutella xylostella

Se Hui Hwang
Abstract We cloned a full-length tyrosine hydroxylase cDNA from the integument of the diamondback moth, Plutella xylostella. In the phylogenetic tree, tyrosine hydroxylase (PxTH) clustered with the other lepidopteran THs. Serine residues in the PxTH sequence, namely Ser24, Ser31, Ser35, Ser53, and Ser65, were predicted to be the target sites for phosphorylation based on PROSITE analysis. In particular, Ser35 of PxTH is highly conserved across a broad phylogenetic range of animal taxa including rat and human. Western blot analysis using both PxTH-Ab1 and PxTH-Ab2 polyclonal antibodies verified the expression of PxTH in all life cycle stages of P. xylostella, namely the larval, pupal, and adult stages. To examine the possible immune function of PxTH in P. xylostella, PxTH gene expression was investigated by RT-PCR and western blotting analysis after challenging P. xylostella with bacteria. PxTH expression was elevated 1,h post-infection and was continued till 12,h of post-infection relative to control larvae injected with sterile water. © 2010 Wiley Periodicals, Inc. [source]

Use of knockout technology to resolve pharmacological problems

J R Docherty
Knock-out (KO) mouse technology has given pharmacologists a powerful tool to study function in the absence of selective antagonists or inhibitors. Such KO technology can confirm predicted function, serendipitously reveal unrecognized function, or help define the mode of action of a drug. In this issue, Liles et al. demonstrate, employing mice unable to synthesize noradrenaline due to the KO of the dopamine- , -hydroxylase gene, that the sympathomimetic actions of ephedrine are directly, rather than indirectly, mediated. This may end 50 years of debate about the actions of ephedrine. British Journal of Pharmacology (2007) 150, 1,2. doi:10.1038/sj.bjp.0706941 [source]

A Novel Mycolactone Toxin Obtained by Biosynthetic Engineering

CHEMBIOCHEM, Issue 17 2007
Hui Hong Dr.
A novel structural variant of the mycobacterial polyketide toxin mycolactone has been obtained by cloning a P450 hydroxylase gene from a related strain. This technique increases the range of available mycolactones for studies on the mode of action of the toxin. [source]

Screening for soluble methane monooxygenase in methanotrophic bacteria using combined molecular and biochemical methods for hydroxylase detection

Stephan Grosse Dr.
Three well known methanotrophic bacteria (Methylosinus trichosporium OB3b, Methylocystis sp. WI 14, and Methylocystis sp. GB 25) and three newly isolated methanotrophic bacteria (Methylocystis sp. WI 11, Methylocystis sp. X, and FI-9) were screened for sMMO considering the existence of hydroxylase (component A) genes as well as its gene expression. For these purposes monoclonal antibodies that specifically recognize each subunit of the hydroxylase of Methylocystis sp. WI 14 (, -subunit [9E5/F2], , -subunit [4E2/G11], , -subunit [10G3/D7]) were produced. PCR amplification using well known primers showed that the hydroxylase encoding genes appear to be only present in M. trichosporium OB3b, Methylocystis sp. WI 11 and WI 14, and in the isolate FI-9. Western and ELISA analysis using the monoclonal antibodies revealed that all subunits of hydroxylase were present. However, in FI-9, only the , -subunit of the hydroxylase might be expressed. Surprisingly, in Methylocystis sp. GB 25, where no sMMO activity and no amplification with sMMO specific primers was obtained, the antibody 4E2/G11 recognized a protein band with exactly the same molecular mass as the , -subunit of the hydroxylase. Methylocystis sp. X showed no positive reaction in any of the tests. In combination with the detection methods currently used, the described antibodies provide a powerful tool for detecting even partially expressed hydroxylase genes. [source]

Expression levels of genes for ATP-binding cassette transporters and sterol 27-hydroxylase in liver and intestine of baboons with high and low cholesterolemic responses to dietary lipids

Rampratap S. Kushwaha
Abstract:, Baboons with high and low lipemic responses to dietary lipids differ in intestinal cholesterol absorption and hepatic cholesterol metabolism. ATP-binding cassette (ABC) transporters play an important role in cholesterol absorption and hepatic cholesterol metabolism. Using frozen tissues from high- and low-responding baboons maintained on the cholesterol and fat-enriched diet, we determined the relative expression of ABCA1, ABCG5, ABCG8, and 27-hydroxylase genes in the liver and intestine using TaqMan® real-time polymerase chain reaction. There was no consistent difference in the expression of ABC-transporters and 27-hydroxylase in the intestine between high- and low-responding baboons. However, hepatic expression of sterol 27-hydroxylase, ABCG5, and ABCG8 was higher in low-responding baboons than in high-responding baboons. There was also a significant correlation between the expression of sterol 27-hydroxylase and ABCG5, and ABCG8 in both the liver and the intestine. These results suggest that differences in hepatic lipid metabolism but not in cholesterol absorption between high- and low-responding baboons observed previously may be mediated by the differences in the expression levels of 27-hydroxylase, ABCG5, and ABCG8. [source]