1
|
Jung-Klawitter S, Richter P, Yuan Y, Welzel K, Kube M, Bähr S, Leibner A, Flory E, Opladen T. Tyrosine hydroxylase variants influence protein expression, cellular localization, stability, enzymatic activity and the physical interaction between tyrosine hydroxylase and GTP cyclohydrolase 1. J Inherit Metab Dis 2024; 47:517-532. [PMID: 38084654 DOI: 10.1002/jimd.12690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 10/17/2023] [Accepted: 11/03/2023] [Indexed: 05/16/2024]
Abstract
Tyrosine hydroxylase (TH) is the rate-limiting enzyme in dopamine biosynthesis catalyzing the tetrahydrobiopterin (BH4)-dependent hydroxylation of tyrosine to L-DOPA. Here, we analyzed 25 TH variants associated with various degrees of dopa-responsive dystonia and evaluate the effect of each variant on protein stability, activity and cellular localization. Furthermore, we investigated the physical interaction between TH and human wildtype (wt) GTP cyclohydrolase 1 (GTPCH) and the effect of variants on this interaction. Our in vitro results classify variants according to their resistance to proteinase K digestion into three groups (stable, intermediate, unstable). Based on their cellular localization, two groups of variants can be identified, variant group one with cytoplasmic distribution and variant group two forming aggregates. These aggregates do not correlate with loss of enzymatic activity but nevertheless might be a good target for molecular chaperones. Unfortunately, no obvious correlation between the half-life of a variant and its enzymatic activity or between solubility, stability and enzymatic activity of a given variant could be found. Excitingly, some variants disrupt the physical interaction between TH and human wildtype GTPCH, thereby interfering with enzymatic activity and offering new druggable targets for therapy. Taken together, our results highlight the importance of an in-depth molecular analysis of each variant in order to be able to classify groups of disease variants and to find specific therapies for each subgroup. Stand-alone in silico analyses predict less precise the effect of specific variants and should be combined with other in vitro analyses in cellular model systems.
Collapse
Affiliation(s)
- Sabine Jung-Klawitter
- Medical Faculty, Center for Child and Adolescent Medicine, Pediatric Clinic I, Section of Neuropediatrics and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Petra Richter
- Medical Faculty, Center for Child and Adolescent Medicine, Pediatric Clinic I, Section of Neuropediatrics and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Yuheng Yuan
- Medical Faculty, Center for Child and Adolescent Medicine, Pediatric Clinic I, Section of Neuropediatrics and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Karin Welzel
- Division of Hematology, Cell and Gene Therapy, Paul-Ehrlich-Institute, Langen, Germany
| | - Marie Kube
- Institute of Molecular Biology, Mainz, Germany
| | - Stella Bähr
- Medical Faculty, Center for Child and Adolescent Medicine, Pediatric Clinic I, Section of Neuropediatrics and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Alexander Leibner
- Medical Faculty, Center for Child and Adolescent Medicine, Pediatric Clinic I, Section of Neuropediatrics and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Egbert Flory
- Division of Hematology, Cell and Gene Therapy, Paul-Ehrlich-Institute, Langen, Germany
| | - Thomas Opladen
- Medical Faculty, Center for Child and Adolescent Medicine, Pediatric Clinic I, Section of Neuropediatrics and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| |
Collapse
|
2
|
Ze LJ, Xu P, Wu JJ, Jin L, Ali Anjum A, Li GQ. Disruption of tetrahydrobiopterin (BH4) biosynthesis pathway affects cuticle pigmentation in Henosepilachna vigintioctopunctata. JOURNAL OF INSECT PHYSIOLOGY 2023; 144:104457. [PMID: 36427533 DOI: 10.1016/j.jinsphys.2022.104457] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 11/18/2022] [Accepted: 11/19/2022] [Indexed: 06/16/2023]
Abstract
Tetrahydrobiopterin (BH4) is produced from guanosine triphosphate (GTP) under catalyzation of GTP cyclohydrolase I (GTPCH), 6-pyruvoyltetrahydropterin synthase (PTPS) and sepiapterin reductase (SR), among others. In Drosophila melanogaster, BH4 and other pteridines are required for cuticle tanning and eye pigmentation. In this study, two Hvgtpch (Hvgtpch-a and Hvgtpch-b), an Hvptps and an Hvsr transcripts were identified in a serious defoliator Henosepilachna vigintioctopunctata. Hvgtpch-a and Hvgtpch-b were highly expressed just before and/or right after the molt, in contrast to Hvptps and Hvsr. RNA interference (RNAi) by injection of a dsgtpch targeting the common fragment of Hvgtpch-a and Hvgtpch-b into the third instar larvae caused albino fourth-instar larvae and pupae. Around 80% of the Hvgtpch RNAi larvae failed to pupate. The remaining 20% of Hvgtpch RNAi pupated beetles did not completely remove the larval/pupal exuviae after emerged as adults and eventually died. Depletion of Hvgtpch at the fourth instar stage resulted in under-pigmented pupae and adults, with significantly low pupation and emergence rates. The Hvgtpch RNAi adults rarely moved and fed on plant leaves; they died within a week after emergence. Silence of Hvptps or Hvsr at the third- and fourth-instar stages led to similar but less serious phenotypes, with lowest influence in the Hvsr RNAi ladybirds. Moreover, RNAi of Hvgtpch, Hvptps or Hvsr did not affect coloration of the larval ocelli and pupal/adult compound eyes. Therefore, our results demonstrated that pteridines are involved in melanin formation but not in eye pigmentation in H. vigintioctopunctata. Moreover, our findings will enable the development of a dsgtpch-based pesticide to control H. vigintioctopunctata larvae.
Collapse
Affiliation(s)
- Long-Ji Ze
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Ping Xu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Jian-Jian Wu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Lin Jin
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Ahmad Ali Anjum
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Guo-Qing Li
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| |
Collapse
|
3
|
Larbalestier H, Keatinge M, Watson L, White E, Gowda S, Wei W, Koler K, Semenova SA, Elkin AM, Rimmer N, Sweeney ST, Mazzolini J, Sieger D, Hide W, McDearmid J, Panula P, MacDonald RB, Bandmann O. GCH1 Deficiency Activates Brain Innate Immune Response and Impairs Tyrosine Hydroxylase Homeostasis. J Neurosci 2022; 42:702-716. [PMID: 34876467 PMCID: PMC8805627 DOI: 10.1523/jneurosci.0653-21.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 10/08/2021] [Accepted: 11/03/2021] [Indexed: 11/21/2022] Open
Abstract
The Parkinson's disease (PD) risk gene GTP cyclohydrolase 1 (GCH1) catalyzes the rate-limiting step in tetrahydrobiopterin (BH4) synthesis, an essential cofactor in the synthesis of monoaminergic neurotransmitters. To investigate the mechanisms by which GCH1 deficiency may contribute to PD, we generated a loss of function zebrafish gch1 mutant (gch1-/-), using CRISPR/Cas technology. gch1-/- zebrafish develop marked monoaminergic neurotransmitter deficiencies by 5 d postfertilization (dpf), movement deficits by 8 dpf and lethality by 12 dpf. Tyrosine hydroxylase (Th) protein levels were markedly reduced without loss of ascending dopaminergic (DAergic) neurons. L-DOPA treatment of gch1-/- larvae improved survival without ameliorating the motor phenotype. RNAseq of gch1-/- larval brain tissue identified highly upregulated transcripts involved in innate immune response. Subsequent experiments provided morphologic and functional evidence of microglial activation in gch1-/- The results of our study suggest that GCH1 deficiency may unmask early, subclinical parkinsonism and only indirectly contribute to neuronal cell death via immune-mediated mechanisms. Our work highlights the importance of functional validation for genome-wide association studies (GWAS) risk factors and further emphasizes the important role of inflammation in the pathogenesis of PD.SIGNIFICANCE STATEMENT Genome-wide association studies have now identified at least 90 genetic risk factors for sporadic Parkinson's disease (PD). Zebrafish are an ideal tool to determine the mechanistic role of genome-wide association studies (GWAS) risk genes in a vertebrate animal model. The discovery of GTP cyclohydrolase 1 (GCH1) as a genetic risk factor for PD was counterintuitive, GCH1 is the rate-limiting enzyme in the synthesis of dopamine (DA), mutations had previously been described in the non-neurodegenerative movement disorder dopa-responsive dystonia (DRD). Rather than causing DAergic cell death (as previously hypothesized by others), we now demonstrate that GCH1 impairs tyrosine hydroxylase (Th) homeostasis and activates innate immune mechanisms in the brain and provide evidence of microglial activation and phagocytic activity.
Collapse
Affiliation(s)
- Hannah Larbalestier
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Marcus Keatinge
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
- Centre for Discovery Brain Sciences, Chancellor's Building, The University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - Lisa Watson
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Emma White
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Siri Gowda
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Wenbin Wei
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
| | - Katjusa Koler
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
| | - Svetlana A Semenova
- Department of Anatomy, University of Helsinki, Helsinki, Finland, 00014
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892
| | - Adam M Elkin
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Neal Rimmer
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Sean T Sweeney
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Julie Mazzolini
- Centre for Discovery Brain Sciences, Chancellor's Building, The University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - Dirk Sieger
- Centre for Discovery Brain Sciences, Chancellor's Building, The University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - Winston Hide
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Department of Pathology, Beth Israel Medical Center, Boston, Massachusetts 02215
- Harvard Medical School, Boston, Massachusetts 02115
| | - Jonathan McDearmid
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Pertti Panula
- Department of Anatomy, University of Helsinki, Helsinki, Finland, 00014
| | - Ryan B MacDonald
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Oliver Bandmann
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| |
Collapse
|
4
|
Xiao G, Zhao M, Liu Z, Du F, Zhou B. Zinc antagonizes iron-regulation of tyrosine hydroxylase activity and dopamine production in Drosophila melanogaster. BMC Biol 2021; 19:236. [PMID: 34732185 PMCID: PMC8564973 DOI: 10.1186/s12915-021-01168-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 10/15/2021] [Indexed: 12/21/2022] Open
Abstract
Background Dopamine (DA) is a neurotransmitter that plays roles in movement, cognition, attention, and reward responses, and deficient DA signaling is associated with the progression of a number of neurological diseases, such as Parkinson’s disease. Due to its critical functions, DA expression levels in the brain are tightly controlled, with one important and rate-limiting step in its biosynthetic pathway being catalyzed by tyrosine hydroxylase (TH), an enzyme that uses iron ion (Fe2+) as a cofactor. A role for metal ions has additionally been associated with the etiology of Parkinson’s disease. However, the way dopamine synthesis is regulated in vivo or whether regulation of metal ion levels is a component of DA synthesis is not fully understood. Here, we analyze the role of Catsup, the Drosophila ortholog of the mammalian zinc transporter SLC39A7 (ZIP7), in regulating dopamine levels. Results We found that Catsup is a functional zinc transporter that regulates intracellular zinc distribution between the ER/Golgi and the cytosol. Loss-of-function of Catsup leads to increased DA levels, and we showed that the increased dopamine production is due to a reduction in zinc levels in the cytosol. Zinc ion (Zn2+) negatively regulates dopamine synthesis through direct inhibition of TH activity, by antagonizing Fe2+ binding to TH, thus rendering the enzyme ineffective or non-functional. Conclusions Our findings uncovered a previously unknown mechanism underlying the control of cellular dopamine expression, with normal levels of dopamine synthesis being maintained through a balance between Fe2+ and Zn2+ ions. The findings also provide support for metal modulation as a possible therapeutic strategy in the treatment of Parkinson’s disease and other dopamine-related diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01168-0.
Collapse
Affiliation(s)
- Guiran Xiao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.,School of Food and Biological Engineering, Hefei University of Technology, Hefei, 230009, Anhui, China
| | - Mengran Zhao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Zhihua Liu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, 230009, Anhui, China
| | - Fan Du
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Bing Zhou
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| |
Collapse
|
5
|
Khairallah A, Ross CJ, Tastan Bishop Ö. GTP Cyclohydrolase I as a Potential Drug Target: New Insights into Its Allosteric Modulation via Normal Mode Analysis. J Chem Inf Model 2021; 61:4701-4719. [PMID: 34450011 DOI: 10.1021/acs.jcim.1c00898] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Guanosine triphosphate (GTP) cyclohydrolase I (GCH1) catalyzes the conversion of GTP into dihydroneopterin triphosphate (DHNP). DHNP is the first intermediate of the folate de novo biosynthesis pathway in prokaryotic and lower eukaryotic microorganisms and the tetrahydrobiopterin (BH4) biosynthesis pathway in higher eukaryotes. The de novo folate biosynthesis provides essential cofactors for DNA replication, cell division, and synthesis of key amino acids in rapidly replicating pathogen cells, such as Plasmodium falciparum (P. falciparum), a causative agent of malaria. In eukaryotes, the product of the BH4 biosynthesis pathway is essential for the production of nitric oxide and several neurotransmitter precursors. An increased copy number of the malaria parasite P. falciparum GCH1 gene has been reported to influence antimalarial antifolate drug resistance evolution, whereas mutations in the human GCH1 are associated with neuropathic and inflammatory pain disorders. Thus, GCH1 stands as an important and attractive drug target for developing therapeutics. The GCH1 intrinsic dynamics that modulate its activity remains unclear, and key sites that exert allosteric effects across the structure are yet to be elucidated. This study employed the anisotropic network model to analyze the intrinsic motions of the GCH1 structure alone and in complex with its regulatory partner protein. We showed that the GCH1 tunnel-gating mechanism is regulated by a global shear motion and an outward expansion of the central five-helix bundle. We further identified hotspot residues within sites of structural significance for the GCH1 intrinsic allosteric modulation. The obtained results can provide a solid starting point to design novel antineuropathic treatments for humans and novel antimalarial drugs against the malaria parasite P. falciparum GCH1 enzyme.
Collapse
Affiliation(s)
- Afrah Khairallah
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, South Africa
| | - Caroline J Ross
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, South Africa
| | - Özlem Tastan Bishop
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, South Africa
| |
Collapse
|
6
|
Emery O, Schmidt K, Engel P. Immune system stimulation by the gut symbiont Frischella perrara in the honey bee (Apis mellifera). Mol Ecol 2017; 26:2576-2590. [PMID: 28207182 DOI: 10.1111/mec.14058] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 02/01/2017] [Accepted: 02/02/2017] [Indexed: 12/24/2022]
Abstract
Gut bacteria engage in various symbiotic interactions with their host and impact gut immunity and homeostasis in different ways. In honey bees, the gut microbiota is composed of a relatively simple, but highly specialized bacterial community. One of its members, the gammaproteobacterium Frischella perrara induces the so-called scab phenotype, a dark-coloured band that develops on the epithelial surface of the pylorus. To understand the underlying host response, we analysed transcriptome changes in the pylorus in response to bacterial colonization. We find that, in contrast to the gut bacterium Snodgrassella alvi, F. perrara causes strong activation of the host immune system. Besides pattern recognition receptors, antimicrobial peptides and transporter genes, the melanization cascade was upregulated by F. perrara, suggesting that the scab phenotype corresponds to a melanization response of the host. In addition, transcriptome analysis of hive bees with and without the scab phenotype showed that F. perrara also stimulates the immune system under in-hive conditions in the presence of other gut bacterial species. Collectively, our study demonstrates that the presence of F. perrara influences gut immunity and homeostasis in the pylorus. This may have implications for bee health, because F. perrara prevalence differs between colonies and increased abundance of this bacterium has been shown to correlate with dietary alteration and impaired host development. Our transcriptome analysis sets the groundwork for investigating the interplay of bee gut symbionts with the host immune system.
Collapse
Affiliation(s)
- Olivier Emery
- Department of Fundamental Microbiology, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Konstantin Schmidt
- Department of Fundamental Microbiology, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Philipp Engel
- Department of Fundamental Microbiology, University of Lausanne, CH-1015, Lausanne, Switzerland
| |
Collapse
|
7
|
Chen P, Wang J, Li H, Li Y, Chen P, Li T, Chen X, Xiao J, Zhang L. Role of GTP-CHI links PAH and TH in melanin synthesis in silkworm, Bombyx mori. Gene 2015; 567:138-45. [PMID: 25958343 DOI: 10.1016/j.gene.2015.03.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 10/23/2022]
Abstract
In insects, pigment patterns are formed by melanin, ommochromes, and pteridines. Here, the effects of pteridine synthesis on melanin formation were studied using 4th instar larvae of a wild-type silkworm strain, dazao (Bombyx mori), with normal color and markings. Results from injected larvae and in vitro integument culture indicated that decreased activity of guanosine triphosphate cyclohydrolase I (GTP-CH I, a rate-limiting enzyme for pteridine synthesis), lowers BH4 (6R-l-erythro-5,6,7,8-tetrahydrobiopterin, a production correlated with GTP-CH I activity) levels and eliminates markings and coloration. The conversion of phenylalanine and tyrosine to melanin was prevented when GTP-CH I was inhibited. When BH4 was added, phenylalanine was converted to tyrosine, and the tyrosine concentration increased. Tyrosine was then converted to melanin to create normal markings and coloration. Decreasing GTP-CH I activity did not affect L-DOPA (3,4-l-dihydroxyphenylalanine). GTP-CH I affected melanin synthesis by generating the BH4 used in two key reaction steps: (1) conversion of phenylalanine to tyrosine by PAH (phenylalanine hydroxylase) and (2) conversion of tyrosine to L-DOPA by TH (tyrosine hydroxylase). Expression profiles of BmGTPCH Ia, BmGTPCH Ib, BmTH, and BmPAH in the integument were consistent with the current findings.
Collapse
Affiliation(s)
- Ping Chen
- College of Biotechnology, Southwest University, Chongqing 400716, China.
| | - Jiying Wang
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Haiyin Li
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Yan Li
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Peng Chen
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Tian Li
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Xi Chen
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Junjie Xiao
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Liang Zhang
- College of Biotechnology, Southwest University, Chongqing 400716, China
| |
Collapse
|
8
|
Wakabayashi-Ito N, Ajjuri RR, Henderson BW, Doherty OM, Breakefield XO, O'Donnell JM, Ito N. Mutant human torsinA, responsible for early-onset dystonia, dominantly suppresses GTPCH expression, dopamine levels and locomotion in Drosophila melanogaster. Biol Open 2015; 4:585-95. [PMID: 25887123 PMCID: PMC4434810 DOI: 10.1242/bio.201411080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Dystonia represents the third most common movement disorder in humans with over 20 genetic loci identified. TOR1A (DYT1), the gene responsible for the most common primary hereditary dystonia, encodes torsinA, an AAA ATPase family protein. Most cases of DYT1 dystonia are caused by a 3 bp (ΔGAG) deletion that results in the loss of a glutamic acid residue (ΔE302/303) in the carboxyl terminal region of torsinA. This torsinAΔE mutant protein has been speculated to act in a dominant-negative manner to decrease activity of wild type torsinA. Drosophila melanogaster has a single torsin-related gene, dtorsin. Null mutants of dtorsin exhibited locomotion defects in third instar larvae. Levels of dopamine and GTP cyclohydrolase (GTPCH) proteins were severely reduced in dtorsin-null brains. Further, the locomotion defect was rescued by the expression of human torsinA or feeding with dopamine. Here, we demonstrate that human torsinAΔE dominantly inhibited locomotion in larvae and adults when expressed in neurons using a pan-neuronal promoter Elav. Dopamine and tetrahydrobiopterin (BH4) levels were significantly reduced in larval brains and the expression level of GTPCH protein was severely impaired in adult and larval brains. When human torsinA and torsinAΔE were co-expressed in neurons in dtorsin-null larvae and adults, the locomotion rates and the expression levels of GTPCH protein were severely reduced. These results support the hypothesis that torsinAΔE inhibits wild type torsinA activity. Similarly, neuronal expression of a Drosophila DtorsinΔE equivalent mutation dominantly inhibited larval locomotion and GTPCH protein expression. These results indicate that both torsinAΔE and DtorsinΔE act in a dominant-negative manner. We also demonstrate that Dtorsin regulates GTPCH expression at the post-transcriptional level. This Drosophila model of DYT1 dystonia provides an important tool for studying the differences in the molecular function between the wild type and the mutant torsin proteins.
Collapse
Affiliation(s)
- Noriko Wakabayashi-Ito
- Department of Neurology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, MA 02129, USA
| | - Rami R Ajjuri
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Benjamin W Henderson
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Olugbenga M Doherty
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Xandra O Breakefield
- Department of Neurology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, MA 02129, USA
| | - Janis M O'Donnell
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Naoto Ito
- Department of Neurology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, MA 02129, USA
| |
Collapse
|
9
|
Ajjuri RR, Hall M, Reiter LT, O’Donnell JM. Drosophila. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00005-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
|
10
|
Meiser J, Weindl D, Hiller K. Complexity of dopamine metabolism. Cell Commun Signal 2013; 11:34. [PMID: 23683503 PMCID: PMC3693914 DOI: 10.1186/1478-811x-11-34] [Citation(s) in RCA: 414] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 05/10/2013] [Indexed: 01/15/2023] Open
Abstract
: Parkinson's disease (PD) coincides with a dramatic loss of dopaminergic neurons within the substantia nigra. A key player in the loss of dopaminergic neurons is oxidative stress. Dopamine (DA) metabolism itself is strongly linked to oxidative stress as its degradation generates reactive oxygen species (ROS) and DA oxidation can lead to endogenous neurotoxins whereas some DA derivatives show antioxidative effects. Therefore, DA metabolism is of special importance for neuronal redox-homeostasis and viability.In this review we highlight different aspects of dopamine metabolism in the context of PD and neurodegeneration. Since most reviews focus only on single aspects of the DA system, we will give a broader overview by looking at DA biosynthesis, sequestration, degradation and oxidation chemistry at the metabolic level, as well as at the transcriptional, translational and posttranslational regulation of all enzymes involved. This is followed by a short overview of cellular models currently used in PD research. Finally, we will address the topic from a medical point of view which directly aims to encounter PD.
Collapse
Affiliation(s)
- Johannes Meiser
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, 7, avenue des Hauts-Fourneaux, L-4362 Esch-Belval, Luxembourg
| | - Daniel Weindl
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, 7, avenue des Hauts-Fourneaux, L-4362 Esch-Belval, Luxembourg
| | - Karsten Hiller
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, 7, avenue des Hauts-Fourneaux, L-4362 Esch-Belval, Luxembourg
| |
Collapse
|
11
|
Gunaratna RT, Jiang H. A comprehensive analysis of the Manduca sexta immunotranscriptome. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2013; 39. [PMID: 23178408 PMCID: PMC3595354 DOI: 10.1016/j.dci.2012.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
As a biochemical model, Manduca sexta has substantially contributed to our knowledge on insect innate immunity. The RNA-Seq approach was implemented in three studies to examine tissue immunotranscriptomes of this species. With the latest and largest focusing on highly regulated process- and tissue-specific genes, we further analyzed the same set of data using BLAST2GO to explore functional aspects of the larval fat body (F) and hemocyte (H) transcriptomes with (I) or without (C) immune challenge. Using immunity-related sequences from other insects, we found 383 homologous contigs and compared them with those discovered based on relative abundance changes. The major overlap of the two lists validated our previous research designed for gene discovery and transcript profiling in organisms lacking sequenced genomes. By concatenating the contigs, we established a repertoire of 232 immunity-related genes encoding proteins for pathogen recognition (16%), signal transduction (53%), microbe killing (13%) and others (18%). We examined their transcript levels along with attribute classifications and detected prominent differences in nine of the 30 level 2 gene ontology (GO) categories. The increase in extracellular proteins (155%) was consistent with the highly induced synthesis of defense molecules (e.g., antimicrobial peptides) in fat body after the immune challenge. We identified most members of the putative Toll, IMD, MAPK-JNK-p38 and JAK-STAT pathways and small changes in their mRNA levels. Together, these findings set the stage for on-going analysis of the M. sexta immunogenome.
Collapse
Affiliation(s)
- Ramesh T Gunaratna
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | | |
Collapse
|
12
|
Abstract
6R l-erythro-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for several enzymes including phenylalanine hydroxylase and the nitric oxide synthases (NOS). Oral supplementation of BH4 has been successfully employed to treat subsets of patients with hyperphenylalaninaemia. More recently, research efforts have focussed on understanding whether BH4 supplementation may also be efficacious in cardiovascular disorders that are underpinned by reduced nitric oxide bioavailability. Whilst numerous preclinical and clinical studies have demonstrated a positive association between enhanced BH4 and vascular function, the efficacy of orally administered BH4 in human cardiovascular disease remains unclear. Furthermore, interventions that limit BH4 bioavailability may provide benefit in diseases where nitric oxide over production contributes to pathology. This review describes the pathways involved in BH4 bio-regulation and discusses other endogenous mechanisms that could be harnessed therapeutically to manipulate vascular BH4 levels.
Collapse
Affiliation(s)
- Anna Starr
- Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College London, Franklin Wilkins Building, 150 Stamford Street,London SE1 9NH, United Kingdom
| | | | | |
Collapse
|
13
|
Caldwell KA, Shu Y, Roberts NB, Caldwell GA, O’Donnell JM. Invertebrate models of dystonia. Curr Neuropharmacol 2013; 11:16-29. [PMID: 23814534 PMCID: PMC3580786 DOI: 10.2174/157015913804999504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 06/02/2012] [Accepted: 07/03/2012] [Indexed: 01/15/2023] Open
Abstract
The neurological movement disorder dystonia is an umbrella term for a heterogeneous group of related conditions where at least 20 monogenic forms have been identified. Despite the substantial advances resulting from the identification of these loci, the function of many DYT gene products remains unclear. Comparative genomics using simple animal models to examine the evolutionarily conserved functional relationships with monogenic dystonias represents a rapid route toward a comprehensive understanding of these movement disorders. Current studies using the invertebrate animal models Caenorhabditis elegans and Drosophila melanogaster are uncovering cellular functions and mechanisms associated with mutant forms of the well-conserved gene products corresponding to DYT1, DYT5a, DYT5b, and DYT12 dystonias. Here we review recent findings from the invertebrate literature pertaining to molecular mechanisms of these gene products, torsinA, GTP cyclohydrolase I, tyrosine hydroxylase, and the alpha subunit of Na+/K ATPase, respectively. In each study, the application of powerful genetic tools developed over decades of intensive work with both of these invertebrate systems has led to mechanistic insights into these human disorders. These models are particularly amenable to large-scale genetic screens for modifiers or additional alleles, which are bolstering our understanding of the molecular functions associated with these gene products. Moreover, the use of invertebrate models for the evaluation of DYT genetic loci and their genetic interaction networks has predictive value and can provide a path forward for therapeutic intervention.
Collapse
Affiliation(s)
- Kim A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | | | | | | | | |
Collapse
|
14
|
The Protective Effect of Minocycline in a Paraquat-Induced Parkinson's Disease Model in Drosophila is Modified in Altered Genetic Backgrounds. PARKINSONS DISEASE 2012; 2012:938528. [PMID: 22900232 PMCID: PMC3413958 DOI: 10.1155/2012/938528] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 06/04/2012] [Indexed: 12/21/2022]
Abstract
Epidemiological studies link the herbicide paraquat to increased incidence of Parkinson's disease (PD). We previously reported that Drosophila exposed to paraquat recapitulate PD symptoms, including region-specific degeneration of dopaminergic neurons. Minocycline, a tetracycline derivative, exerts ameliorative effects in neurodegenerative disease models, including Drosophila. We investigated whether our environmental toxin-based PD model could contribute to an understanding of cellular and genetic mechanisms of minocycline action and whether we could assess potential interference with these drug effects in altered genetic backgrounds. Cofeeding of minocycline with paraquat prolonged survival, rescued mobility defects, blocked generation of reactive oxygen species, and extended dopaminergic neuron survival, as has been reported previously for a genetic model of PD in Drosophila. We then extended this study to identify potential interactions of minocycline with genes regulating dopamine homeostasis that might modify protection against paraquat and found that deficits in GTP cyclohydrolase adversely affect minocycline rescue. We further performed genetic studies to identify signaling pathways that are necessary for minocycline protection against paraquat toxicity and found that mutations in the Drosophila genes that encode c-Jun N-terminal kinase (JNK) and Akt/Protein kinase B block minocycline rescue.
Collapse
|
15
|
Wang Z, Ferdousy F, Lawal H, Huang Z, Daigle JG, Izevbaye I, Doherty O, Thomas J, Stathakis DG, O'Donnell JM. Catecholamines up integrates dopamine synthesis and synaptic trafficking. J Neurochem 2011; 119:1294-305. [PMID: 21985068 DOI: 10.1111/j.1471-4159.2011.07517.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The highly reactive nature of dopamine renders dopaminergic neurons vulnerable to oxidative damage. We recently demonstrated that loss-of-function mutations in the Drosophila gene Catecholamines up (Catsup) elevate dopamine pools but, paradoxically, also confer resistance to paraquat, an herbicide that induces oxidative stress-mediated toxicity in dopaminergic neurons. We now report a novel association of the membrane protein, Catsup, with GTP cyclohydrolase rate-limiting enzyme for tetrahydrobiopterin (BH(4)) biosynthesis and tyrosine hydroxylase, rate-limiting enzyme for dopamine biosynthesis, which requires BH(4) as a cofactor. Loss-of-function Catsup mutations cause dominant hyperactivation of both enzymes. Elevated dopamine levels in Catsup mutants coincide with several distinct characteristics, including hypermobility, minimal basal levels of 3,4-dihydroxy-phenylacetic acid, an oxidative metabolite of dopamine, and resistance to the vesicular monoamine transporter inhibitor, reserpine, suggesting that excess dopamine is synaptically active and that Catsup functions in the regulation of synaptic vesicle loading and release of dopamine. We conclude that Catsup regulates and links the dopamine synthesis and transport networks.
Collapse
Affiliation(s)
- Zhe Wang
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Wakabayashi-Ito N, Doherty OM, Moriyama H, Breakefield XO, Gusella JF, O'Donnell JM, Ito N. Dtorsin, the Drosophila ortholog of the early-onset dystonia TOR1A (DYT1), plays a novel role in dopamine metabolism. PLoS One 2011; 6:e26183. [PMID: 22022556 PMCID: PMC3192163 DOI: 10.1371/journal.pone.0026183] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 09/22/2011] [Indexed: 12/14/2022] Open
Abstract
Dystonia represents the third most common movement disorder in humans. At least 15 genetic loci (DYT1-15) have been identified and some of these genes have been cloned. TOR1A (formally DYT1), the gene responsible for the most common primary hereditary dystonia, encodes torsinA, an AAA ATPase family protein. However, the function of torsinA has yet to be fully understood. Here, we have generated and characterized a complete loss-of-function mutant for dtorsin, the only Drosophila ortholog of TOR1A. Null mutation of the X-linked dtorsin was semi-lethal with most male flies dying by the pre-pupal stage and the few surviving adults being sterile and slow moving, with reduced cuticle pigmentation and thin, short bristles. Third instar male larvae exhibited locomotion defects that were rescued by feeding dopamine. Moreover, biochemical analysis revealed that the brains of third instar larvae and adults heterozygous for the loss-of-function dtorsin mutation had significantly reduced dopamine levels. The dtorsin mutant showed a very strong genetic interaction with Pu (Punch: GTP cyclohydrolase), the ortholog of the human gene underlying DYT14 dystonia. Biochemical analyses revealed a severe reduction of GTP cyclohydrolase protein and activity, suggesting that dtorsin plays a novel role in dopamine metabolism as a positive-regulator of GTP cyclohydrolase protein. This dtorsin mutant line will be valuable for understanding this relationship and potentially other novel torsin functions that could play a role in human dystonia.
Collapse
Affiliation(s)
- Noriko Wakabayashi-Ito
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Neurology and Radiology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Olugbenga M. Doherty
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Hideaki Moriyama
- School of Biological Science, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Xandra O. Breakefield
- Department of Neurology and Radiology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, United States of America
| | - James F. Gusella
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Janis M. O'Donnell
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Naoto Ito
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Neurology and Radiology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
17
|
Blenau W, Thamm M. Distribution of serotonin (5-HT) and its receptors in the insect brain with focus on the mushroom bodies: lessons from Drosophila melanogaster and Apis mellifera. ARTHROPOD STRUCTURE & DEVELOPMENT 2011; 40:381-394. [PMID: 21272662 DOI: 10.1016/j.asd.2011.01.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 01/05/2011] [Accepted: 01/14/2011] [Indexed: 05/30/2023]
Abstract
The biogenic amine serotonin (5-hydroxytryptamine, 5-HT) plays a key role in regulating and modulating various physiological and behavioral processes in both protostomes and deuterostomes. The specific functions of serotonin are mediated by its binding to and subsequent activation of membrane receptors. The vast majority of these receptors belong to the superfamily of G-protein-coupled receptors. We report here the in vivo expression pattern of a recently characterized 5-HT(1) receptor of the honeybee Apis mellifera (Am5-HT(1A)) in the mushroom bodies. In addition, we summarize current knowledge on the distribution of serotonin and serotonin receptor subtypes in the brain and specifically in the mushroom bodies of the fruit fly Drosophila melanogaster and the honeybee. Functional studies in these two species have shown that serotonergic signaling participates in various behaviors including aggression, sleep, circadian rhythms, responses to visual stimuli, and associative learning. The molecular, pharmacological, and functional properties of identified 5-HT receptor subtypes from A. mellifera and D. melanogaster will also be summarized in this review.
Collapse
Affiliation(s)
- Wolfgang Blenau
- Institute of Biochemistry and Biology, University of Potsdam, Germany.
| | | |
Collapse
|
18
|
Ferdousy F, Bodeen W, Summers K, Doherty O, Wright O, Elsisi N, Hilliard G, O'Donnell JM, Reiter LT. Drosophila Ube3a regulates monoamine synthesis by increasing GTP cyclohydrolase I activity via a non-ubiquitin ligase mechanism. Neurobiol Dis 2010; 41:669-77. [PMID: 21147225 DOI: 10.1016/j.nbd.2010.12.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 11/13/2010] [Accepted: 12/02/2010] [Indexed: 11/18/2022] Open
Abstract
The underlying defects in Angelman syndrome (AS) and autism spectrum disorder (ASD) may be in part due to basic defects in synaptic plasticity and function. In some individuals serotonin reuptake inhibitors, which decrease pre-synaptic re-uptake of serotonin, can ameliorate symptoms, as can resperidone, which blocks both dopamine and serotonin receptors. Loss of maternal UBE3A expression causes AS, while maternal duplications of chromosome 15q11.2-q13 that include the UBE3A gene cause ASD, implicating the maternally expressed UBE3A gene in the ASD phenotype. In a Drosophila screen for proteins regulated by UBE3A, we identified a key regulator of monoamine synthesis, the gene Punch, or GCH1, encoding the enzyme GTP cyclohydrolase I. Here we show that Dube3a, the fly UBE3A orthologue, regulates Punch/GCH1 in the fly brain. Over-expression of Dube3a elevates tetrahydrobiopterin (THB), the rate-limiting cofactor in monoamine synthesis while loss of Dube3a has the opposite effect. The fluctuations in dopamine levels were associated with hyper- and hypoactivity, respectively, in flies. We show that changes in Punch/GCH1 and dopamine levels do not depend on the ubiquitin ligase catalytic domain of Dube3a. In addition, both wild type Dube3a and a ubiquitination-defective Dube3a-C/A form were found at high levels in nuclear fractions and appear to be poly-ubiquitinated in vivo by endogenous Dube3a. We propose that the transcriptional co-activation function of Dube3a may regulate GCH1 activity in the brain. These results provide a connection between monoamine synthesis (dopamine/serotonin) and Dube3a expression that may explain why some individuals with ASD or AS respond better to selective serotonin reuptake inhibitors than others.
Collapse
Affiliation(s)
- Faiza Ferdousy
- Department of Biology, University of Alabama, Box 870344, Tuscaloosa, AL 35487-0344, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Nallamothu G, Dammai V, Hsu T. Developmental function of Nm23/awd: a mediator of endocytosis. Mol Cell Biochem 2009; 329:35-44. [PMID: 19373545 PMCID: PMC2721904 DOI: 10.1007/s11010-009-0112-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 04/02/2009] [Indexed: 10/20/2022]
Abstract
The metastasis suppressor gene Nm23 is highly conserved from yeast to human, implicating a critical developmental function. Studies in cultured mammalian cells have identified several potential functions, but many have not been directly verified in vivo. Here, we summarize the studies on the Drosophila homolog of the Nm23 gene, named a bnormal w ing d iscs (awd), which shares 78% amino acid identity with the human Nm23-H1 and H2 isoforms. These studies confirmed that awd gene encodes a nucleoside diphosphate kinase, and provided strong evidence of a role for awd in regulating cell differentiation and motility via regulation of growth factor receptor signaling. The latter function is mainly mediated by control of endocytosis. This review provides a historical account of the discovery and subsequent analyses of the awd gene. We will also discuss the possible molecular function of the Awd protein that underlies the endocytic function.
Collapse
Affiliation(s)
- Gouthami Nallamothu
- Department of Pathology and Laboratory Medicine, and Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas St., Charleston, SC 29425, USA
| | - Vincent Dammai
- Department of Pathology and Laboratory Medicine, and Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas St., Charleston, SC 29425, USA
| | - Tien Hsu
- Department of Pathology and Laboratory Medicine, and Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas St., Charleston, SC 29425, USA
| |
Collapse
|
20
|
Abstract
Spatial orientation is critical for many behaviors. Intrinsic to the oriented state is the knowledge of past, present, and future spatial location relative to one or more landmarks. How do animals so fluidly solve this problem? Determining mechanisms of orientation may benefit from investigation of relatively simple organisms. Two behaviors that presumably use path integration as a major input to orientation--place learning and persistent target selection--allow for the examination of cellular and neural circuit mechanisms in Drosophila. Although our understanding of these processes is still relatively immature, some recent findings provide insights into the mechanisms supporting orientation. First, place learning provides good access to the past, present, and future aspects of orientation, but currently is less open to understanding how a fly establishes a relationship to landmarks. The change in behavior after learning is orientation away from, and avoiding, a place predicted to punish a fly, incorporating all temporal aspects of orientation, and can last for minutes to hours. This conclusion is supported by several learning phenomena. Second, persistent target selection provides the best access to the processes determining relationships to landmarks. Using a disappearing visual-landmark paradigm, persistent target selection was shown to require parts of the central complex for a seconds-long "path integration memory." How the path integration memory, on this short time scale, is related to longer lasting place memories is, as yet, unknown. Nevertheless, studies of place learning and persistent target selection may provide insights into orientation mechanisms in a simple brain.
Collapse
Affiliation(s)
- Troy Zars
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA.
| |
Collapse
|
21
|
Bowling KM, Huang Z, Xu D, Ferdousy F, Funderburk CD, Karnik N, Neckameyer W, O'Donnell JM. Direct binding of GTP cyclohydrolase and tyrosine hydroxylase: regulatory interactions between key enzymes in dopamine biosynthesis. J Biol Chem 2008; 283:31449-59. [PMID: 18801743 PMCID: PMC2581565 DOI: 10.1074/jbc.m802552200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 07/24/2008] [Indexed: 11/06/2022] Open
Abstract
The signaling functions of dopamine require a finely tuned regulatory network for rapid induction and suppression of output. A key target of regulation is the enzyme tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, which is activated by phosphorylation and modulated by the availability of its cofactor, tetrahydrobiopterin. The first enzyme in the cofactor synthesis pathway, GTP cyclohydrolase I, is activated by phosphorylation and inhibited by tetrahydrobiopterin. We previously reported that deficits in GTP cyclohydrolase activity in Drosophila heterozygous for mutant alleles of the gene encoding this enzyme led to tightly corresponding diminution of in vivo tyrosine hydroxylase activity that could not be rescued by exogenous cofactor. We also found that the two enzymes could be coimmunoprecipitated from tissue extracts and proposed functional interactions between the enzymes that extended beyond provision of cofactor by one pathway for another. Here, we confirm the physical association of these enzymes, identifying interacting regions in both, and we demonstrate that their association can be regulated by phosphorylation. The functional consequences of the interaction include an increase in GTP cyclohydrolase activity, with concomitant protection from end-product feedback inhibition. In vivo, this effect would in turn provide sufficient cofactor when demand for catecholamine synthesis is greatest. The activity of tyrosine hydroxylase is also increased by this interaction, in excess of the stimulation resulting from phosphorylation alone. Vmax is elevated, with no change in Km. These results demonstrate that these enzymes engage in mutual positive regulation.
Collapse
Affiliation(s)
- Kevin M Bowling
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487, USA
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Abstract
Biogenic amines, such as serotonin and dopamine, can be important in reinforcing associative learning. This function is evident as changes in memory performance with manipulation of either of these signals. In the insects, evidence begins to argue for a common role of dopamine in negatively reinforced memory. In contrast, the role of the serotonergic system in reinforcing insect associative learning is either unclear or controversial. We investigated the role of both of these signals in operant place learning in Drosophila. By genetically altering serotonin and dopamine levels, manipulating the neurons that make serotonin and dopamine, and pharmacological treatments we provide clear evidence that serotonin, but not dopamine, is necessary for place memory. Thus, serotonin can be critical for memory formation in an insect, and dopamine is not a universal negatively reinforcing signal.
Collapse
|
23
|
Hsouna A, Lawal HO, Izevbaye I, Hsu T, O'Donnell JM. Drosophila dopamine synthesis pathway genes regulate tracheal morphogenesis. Dev Biol 2007; 308:30-43. [PMID: 17585895 PMCID: PMC1995089 DOI: 10.1016/j.ydbio.2007.04.047] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 04/16/2007] [Accepted: 04/30/2007] [Indexed: 01/11/2023]
Abstract
While studying the developmental functions of the Drosophila dopamine synthesis pathway genes, we noted interesting and unexpected mutant phenotypes in the developing trachea, a tubule network that has been studied as a model for branching morphogenesis. Specifically, Punch (Pu) and pale (ple) mutants with reduced dopamine synthesis show ectopic/aberrant migration, while Catecholamines up (Catsup) mutants that over-express dopamine show a characteristic loss of migration phenotype. We also demonstrate expression of Punch, Ple, Catsup and dopamine in tracheal cells. The dopamine pathway mutant phenotypes can be reproduced by pharmacological treatments of dopamine and a pathway inhibitor 3-iodotyrosine (3-IT), implicating dopamine as a direct mediator of the regulatory function. Furthermore, we show that these mutants genetically interact with components of the endocytic pathway, namely shibire/dynamin and awd/nm23, that promote endocytosis of the chemotactic signaling receptor Btl/FGFR. Consistent with the genetic results, the surface and total cellular levels of a Btl-GFP fusion protein in the tracheal cells and in cultured S2 cells are reduced upon dopamine treatment, and increased in the presence of 3-IT. Moreover, the transducer of Btl signaling, MAP kinase, is hyper-activated throughout the tracheal tube in the Pu mutant. Finally we show that dopamine regulates endocytosis via controlling the dynamin protein level.
Collapse
Affiliation(s)
- Anita Hsouna
- Department of Pathology and Laboratory Medicine, and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | | | | | | | | |
Collapse
|
24
|
Chaudhuri A, Bowling K, Funderburk C, Lawal H, Inamdar A, Wang Z, O'Donnell JM. Interaction of genetic and environmental factors in a Drosophila parkinsonism model. J Neurosci 2007; 27:2457-67. [PMID: 17344383 PMCID: PMC6672491 DOI: 10.1523/jneurosci.4239-06.2007] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 01/02/2007] [Accepted: 01/21/2007] [Indexed: 12/21/2022] Open
Abstract
Catastrophic loss of dopaminergic neurons is a hallmark of Parkinson's disease. Despite the recent identification of genes associated with familial parkinsonism, the etiology of most Parkinson's disease cases is not understood. Environmental toxins, such as the herbicide paraquat, appear to be risk factors, and it has been proposed that susceptibility is influenced by genetic background. The genetic model organism Drosophila is an advantageous system for the identification of genetic susceptibility factors. Genes that affect dopamine homeostasis are candidate susceptibility factors, because dopamine itself has been implicated in neuron damage. We find that paraquat can replicate a broad spectrum of parkinsonian behavioral symptoms in Drosophila that are associated with loss of specific subsets of dopaminergic neurons. In parallel with epidemiological studies that show an increased incidence of Parkinson's disease in males, male Drosophila exhibit paraquat symptoms earlier than females. We then tested the hypothesis that variation in dopamine-regulating genes, including those that regulate tetrahydrobiopterin, a requisite cofactor in dopamine synthesis, can alter susceptibility to paraquat-induced oxidative damage. Drosophila mutant strains that have increased or decreased dopamine and tetrahydrobiopterin production exhibit variation in susceptibility to paraquat. Surprisingly, protection against the neurotoxicity of paraquat is conferred by mutations that elevate dopamine pathway function, whereas mutations that diminish dopamine pools increase susceptibility. We also find that loss-of-function mutations in a negative regulator of dopamine production, Catecholamines-up, delay the onset of neurological symptoms, dopaminergic neuron death, and morbidity during paraquat exposure but confer sensitivity to hydrogen peroxide.
Collapse
Affiliation(s)
- Anathbandhu Chaudhuri
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487-0344
| | - Kevin Bowling
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487-0344
| | - Christopher Funderburk
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487-0344
| | - Hakeem Lawal
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487-0344
| | - Arati Inamdar
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487-0344
| | - Zhe Wang
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487-0344
| | - Janis M. O'Donnell
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487-0344
| |
Collapse
|
25
|
Funderburk CD, Bowling KM, Xu D, Huang Z, O'Donnell JM. A typical N-terminal extensions confer novel regulatory properties on GTP cyclohydrolase isoforms in Drosophila melanogaster. J Biol Chem 2006; 281:33302-12. [PMID: 16966327 DOI: 10.1074/jbc.m602196200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cofactor tetrahydrobiopterin plays critical roles in the modulation of the signaling molecules dopamine, serotonin, and nitric oxide. Deficits in cofactor synthesis have been associated with several human hereditary diseases. Responsibility for the regulation of cofactor pools resides with the first enzyme in its biosynthetic pathway, GTP cyclohydrolase I. Because organisms must be able to rapidly respond to environmental and developmental cues to adjust output of these signaling molecules, complex regulatory mechanisms are vital for signal modulation. Mammalian GTP cyclohydrolase is subject to end-product inhibition via an associated regulatory protein and to positive regulation via phosphorylation, although target residues are unknown. GTP cyclohydrolase is composed of a highly conserved homodecameric catalytic core and non-conserved N-terminal domains proposed to be regulatory sites. We demonstrate for the first time in any organism that the N-terminal arms of the protein serve regulatory functions. We identify two different modes of regulation of the enzyme mediated through the N-terminal domains. The first is end-product feedback inhibition, catalytically similar to that of the mammalian enzyme, except that feedback inhibition by the cofactor requires sequences in the N-terminal arms rather than a separate regulatory protein. The second is a novel inhibitory interaction between the N-terminal arms and the active sites, which can be alleviated through the phosphorylation of serine residues within the N termini. Both mechanisms allow for acute and highly responsive regulation of cofactor production as required by downstream signaling pathways.
Collapse
|
26
|
Abstract
The yeast 2-hybrid system was used to identify protein domains involved in the oligomerization of human guanosine 5'-triphosphate (GTP) Cyclohydrolase I (GCH1) and the interaction of GCH1 with its regulatory partner, GCH1 feedback regulatory protein (GFRP). When interpreted within the structural framework derived from crystallography, our results indicate that the GCH1 N-terminal alpha-helices are not the only domains involved in the formation of dimers from monomers and also suggest an important role for the C-terminal alpha-helix in the assembly of dimers to form decamers. Moreover, a previously unknown role of the extended N-terminal alpha-helix in the interaction of GCH1 and GFRP was revealed. To discover novel GCH1 protein binding partners, we used the yeast 2-hybrid system to screen a human brain library with GCH1 N-terminal amino acids 1-96 as prey. This protruding extension of GCH1 contains two canonical Type-I Src homology-3 (SH3) ligand domains located within amino acids 1-42. Our screen yielded seven unique clones that were subsequently shown to require amino acids 1-42 for binding to GCH1. The interaction of one of these clones, Activator of Heat Shock 90 kDa Protein (Aha1), with GCH1 was validated by glutathione-s-transferase (GST) pull-down assay. Although the physiological relevance of the Aha1-GCH1 interaction requires further study, Aha1 may recruit GCH1 into the endothelial nitric oxide synthase/heat shock protein (eNOS/Hsp90) complex to support changes in endothelial nitric oxide production through the local synthesis of BH4.
Collapse
Affiliation(s)
- Lance Swick
- Cellular and Clinical Neurobiology Program, Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Gregory Kapatos
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Cellular and Clinical Neurobiology Program, Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| |
Collapse
|
27
|
Futahashi R, Fujiwara H. Expression of one isoform of GTP cyclohydrolase I coincides with the larval black markings of the swallowtail butterfly, Papilio xuthus. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2006; 36:63-70. [PMID: 16360951 DOI: 10.1016/j.ibmb.2005.11.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 10/27/2005] [Accepted: 11/02/2005] [Indexed: 05/05/2023]
Abstract
The larva of the swallowtail butterfly Papilio xuthus changes its body markings during the fourth ecdysis. We found that stage-specific cuticular black markings are mainly regulated by co-localization of two melanin synthesis enzymes; tyrosine hydroxylase (TH) and dopa decarboxylase (DDC). TH converts tyrosine to dihydroxyphenylalanine (dopa), and tyrosine itself is converted from phenylalanine by phenylalanine hydroxylase (PAH). Guanosine triphosphate cyclohydrolase I (GTPCHI) is essential for the synthesis of tetrahydrobiopterin (BH4) that is a cofactor of TH and PAH. In this report, we found that a GTPCHI inhibitor prevents pigmentation in cultured integuments, suggesting that the GTPCHI activity is also involved in cuticle pigmentation. We have cloned GTPCHI and PAH cDNAs from P. xuthus and investigated their spatial expression patterns in epidermis by whole-mount in situ hybridization. There are two isoforms of GTPCHI in larval epidermis (GTPCHIa and GTPCHIb). GTPCHIa is expressed at the black markings of the subsequent instar, similar to TH, whereas GTPCHIb is expressed uniformly, similar to PAH. This suggests that the region-specific expression of GTPCHIa supplies sufficient BH(4) reinforcing the TH activity in black marking area. Our results imply that larval markings are regulated by not only melanin synthesis enzymes but also the cofactor supplying enzyme.
Collapse
Affiliation(s)
- Ryo Futahashi
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Bioscience Building 501, Kashiwa, Chiba 277-8562, Japan
| | | |
Collapse
|
28
|
Kealey C, Roche S, Claffey E, McKeon P. Linkage and candidate gene analysis of 14q22-24 in bipolar disorder: support for GCHI as a novel susceptibility gene. Am J Med Genet B Neuropsychiatr Genet 2005; 136B:75-80. [PMID: 15909293 DOI: 10.1002/ajmg.b.30192] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Using a collection of Irish sib-pair nuclear families, we previously obtained modest evidence of linkage implicating 14q22-24 in bipolar disorder (BPD). To follow-up on this preliminary finding, an extended linkage analysis was performed which employed thirteen microsatellite markers, spanning a total distance of 85 cM on 14q. Effectively, P-values <0.05 were observed for a region extending over 41.88 cM, with the marker D14S281 displaying a peak multipoint non-parametric lod (NPL) score of 2.72 and an associated P-value of 0.003. Support for this finding was also obtained from flanking markers indicating excess allele sharing at 14q22-24 in Irish bipolar sib-pairs. A web-based candidate gene search of 14q22-24 resulted in the selection of GTP cyclohydrolase I (GCHI), located 200 kb 3' of D14S281, as the best plausible candidate gene for involvement in BPD. GCHI is the rate-limiting enzyme in the biosynthesis of tetrahydrobiopterin (BH(4)), a natural cofactor for tyrosine and tryptophan hydroxylases. These enzymes play an essential role in the biosynthesis of various hormones and neurotransmitters such as dopamine, noradrenaline, adrenaline, and serotonin. Numerous studies have also suggested that the clinical symptoms of depression might be related to a deficiency of BH(4). An association study between BPD and a novel single nucleotide polymorphism (SNP) in GCHI (G to A at position -959 bp, upstream of the ATG codon), is also presented here. This study revealed that the variant A allele is preferentially transmitted to BPI probands (chi(2) = 4.54, P = 0.033) suggesting that variants within GCHI may contribute to BPD in the Irish population.
Collapse
Affiliation(s)
- Carmel Kealey
- Department of Pharmacology and Centre for Pharmacogenetics, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
| | | | | | | |
Collapse
|
29
|
Zhang YQ, Friedman DB, Wang Z, Woodruff E, Pan L, O'donnell J, Broadie K. Protein Expression Profiling of the Fragile X Mutant Brain Reveals Up-regulation of Monoamine Synthesis. Mol Cell Proteomics 2005; 4:278-90. [PMID: 15634690 DOI: 10.1074/mcp.m400174-mcp200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fragile X syndrome is the most common form of inherited mental retardation, associated with both cognitive and behavioral anomalies. The disease is caused by silencing of the fragile X mental retardation 1 (fmr1) gene, which encodes the mRNA-binding, translational regulator FMRP. Previously we established a disease model through mutation of Drosophila fmr1 (dfmr1) and showed that loss of dFMRP causes defects in neuronal structure, function, and behavioral output similar to the human disease state. To uncover molecular targets of dFMRP in the brain, we use here a proteomic approach involving two-dimensional difference gel electrophoresis analyses followed by mass spectrometry identification of proteins with significantly altered expression in dfmr1 null mutants. We then focus on two misregulated enzymes, phenylalanine hydroxylase (Henna) and GTP cyclohydrolase (Punch), both of which mediate in concert the synthetic pathways of two key monoamine neuromodulators, dopamine and serotonin. Brain enzymatic assays show a nearly 2-fold elevation of Punch activity in dfmr1 null mutants. Consistently brain neurochemical assays show that both dopamine and serotonin are significantly increased in dfmr1 null mutants. At a cellular level, dfmr1 null mutant neurons display a highly significant elevation of the dense core vesicles that package these monoamine neuromodulators for secretion. Taken together, these data indicate that dFMRP normally down-regulates the monoamine pathway, which is consequently up-regulated in the mutant condition. Elevated brain levels of dopamine and serotonin provide a plausible mechanistic explanation for aspects of cognitive and behavioral deficits in human patients.
Collapse
Affiliation(s)
- Yong Q Zhang
- Department of Biological Science, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37232-1634, USA
| | | | | | | | | | | | | |
Collapse
|
30
|
Silverman N, Zhou R, Erlich RL, Hunter M, Bernstein E, Schneider D, Maniatis T. Immune Activation of NF-κB and JNK Requires Drosophila TAK1. J Biol Chem 2003; 278:48928-34. [PMID: 14519762 DOI: 10.1074/jbc.m304802200] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stimulation of the Drosophila immune response activates NF-kappaB and JNK signaling pathways. For example, infection by Gram-negative bacteria induces the Imd signaling pathway, leading to the activation of the NF-kappaB-like transcription factor Relish and the expression of a battery of genes encoding antimicrobial peptides. Bacterial infection also activates the JNK pathway, but the role of this pathway in the immune response has not yet been established. Genetic experiments suggest that the Drosophila homolog of the mammalian MAPK kinase kinase, TAK1 (transforming growth factor beta-activated kinase 1), activates both the JNK and NF-kappaB pathways following immune stimulation. In this report, we demonstrate that Drosophila TAK1 functions as both the Drosophila IkappaB kinase-activating kinase and the JNK kinase-activating kinase. However, we found that JNK signaling is not required for antimicrobial peptide gene expression but is required for the activation of other immune inducible genes, including Punch, sulfated, and malvolio. Thus, JNK signaling appears to play an important role in the cellular immune response and the stress response.
Collapse
Affiliation(s)
- Neal Silverman
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
| | | | | | | | | | | | | |
Collapse
|
31
|
Holdengreber V, Krieger C, Gütlich M, Schramek N, Vechoropoulos M, Fischer M, Bacher A, Ben-Shaul Y. Localization of two enzymes of the tetrahydrobiopterin biosynthetic pathway in embryonic chick retina. J Histochem Cytochem 2002; 50:265-74. [PMID: 11799145 DOI: 10.1177/002215540205000214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Tetrahydrobiopterin (BH4) is an essential co-factor for the biosynthesis of catecholamine-type neurotransmitters and of nitric oxide (NO). The expression of the enzymes catalyzing the first two steps of the BH4 biosynthetic pathway was studied in the developing chicken retina by in situ hybridization and immunocytochemistry. GTP-cyclohydrolase-I (GTP-CH-I) and 6-pyruvoyl-tetrahydropterin synthase (PTPS) were already expressed in the undifferentiated and proliferating retina of E7. At stage E11 both enzymes were expressed in photoreceptors, amacrine cells, displaced amacrine cells, and ganglion cells, and in the plexiform layers in which synaptic connections take place. At stage E18 the labeling was comparable to E11 but appeared to be more concentrated in photoreceptors and ganglion cells.
Collapse
Affiliation(s)
- Vered Holdengreber
- Tel-Aviv University, Department of Cell Research and Immunology, Tel Aviv, Israel
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Campbell JL, Nash HA. Volatile general anesthetics reveal a neurobiological role for the white and brown genes of Drosophila melanogaster. JOURNAL OF NEUROBIOLOGY 2001; 49:339-49. [PMID: 11745669 DOI: 10.1002/neu.10009] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Molecular and cellular evidence argues that a heterodimer between two ABC transporters, the White protein and the Brown protein, is responsible for pumping guanine into pigment-synthesizing cells of the fruit fly, Drosophila melanogaster. Previous studies have not detected White or Brown outside pigment-synthesizing cells nor have behavioral effects of null mutants been reported, other than those that are visually dependent. Nevertheless, we show here that exposure to the volatile general anesthetic (VGA) enflurane reveals a difference in neuromuscular performance between wild-type flies and those that carry a null allele in either the white or brown gene. Specifically, in a test of climbing ability, w1118 or bw1 flies are much less affected by enflurane than are congenic controls. Altered anesthetic sensitivity is still observed when visual cues are reduced or eliminated, arguing that white and brown contribute to neural function outside the eye. This hypothesis is supported by the detection of white message in heads of flies that are genetically altered so as to lack pigment-producing cells. The w1118 or bw1 mutations also alter the response to a second VGA, halothane, albeit somewhat differently. Under some conditions, the combination of w1118 with another mutation that affects anesthesia leads to a drastically altered phenotype. We consider several ways by which diminished transport of guanine could influence neural function and anesthetic sensitivity.
Collapse
Affiliation(s)
- J L Campbell
- Laboratory of Molecular Biology, National Institute of Mental Health, Bethesda, Maryland 20892-4034, USA
| | | |
Collapse
|
33
|
Neckameyer W, O'Donnell J, Huang Z, Stark W. Dopamine and sensory tissue development inDrosophila melanogaster. ACTA ACUST UNITED AC 2001; 47:280-94. [PMID: 11351339 DOI: 10.1002/neu.1035] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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 beta-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 beta-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.
Collapse
Affiliation(s)
- W Neckameyer
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63108, USA.
| | | | | | | |
Collapse
|