GTP Cyclohydrolase I Gene Expression in the Brains of Male and Female <i>hph‐1</i> Mice

Shimoji, Mika; Hirayama, Kei; Hyland, Keith; Kapatos, Gregory

doi:10.1046/j.1471-4159.1999.0720757.x

Cited by 52 publications

(41 citation statements)

References 32 publications

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“…A similar finding is made in the human TH transgenic mouse model, which shows increased TH enzyme activity in the striatum, but only minor changes in the frontal cortex (Kaneda, et al, 1991). The inability to mount a measurable increase in cortical TH enzyme activity may be due to the absence of TH cofactor in this region (Shimoji et al, 1999). The TH enzyme has an obligatory cofactor, tetrahydrobiopterin (BH4), and the TH enzyme is not active in the absence of the local production of the BH4 cofactor (Hwang et al, 1998).…”

Section: Discussionsupporting

confidence: 72%

Non-Invasive Gene Therapy of Experimental Parkinson's Disease

Pardridge¹

2003

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The present research has developed a non-viral gene targeting technology, whereby the effects of a neurotoxin on the brain can be reversed shortly after the intravenous injection of a therapeutic gene medicine without the use of viral vectors. The brain gene targeting technology developed in this work creates an "artificial virus" which is comprised of non-immunogenic lipids and proteins, wherein the therapeutic gene is packaged in the interior of the gene delivery vehicle, which is called a pegylated immunoliposome (PIL). The PIL carrying the gene is a 85 nm "stealth" nanocontainer, which is relatively invisible to the body's reticuloendothelial system, which normally removes nanocontainers from the blood. The surface of the nanocontainer is studded with a receptor-specific monoclonal antibody (MAb). This MAb acts as a moleculr Trojan horse, and triggers the transport of the stealth nanocontainer across the 2 biologicial membrane barriers that separate the blood from the interior of brain cells. These barriers are the brain microvascular endothelial wall, which forms the blood-brain barrier in vivo, and the brain cell plasma membrane. Both barriers express the transferrin receptor, and the anti-receptor MAb enables the PIL to cross the membrane barriers via normal physiological transport processes usually used for endogeneous ligands such as transferrin. With this approach non-viral, non-invasive gene therapy of the brain is now possible. SUBJECT TERMS INTRODUCTIONNeurotoxins can cause serious derangements in brain biochemistry that can comprimise the cognitive and motor function of the individual. In the present studies an animal model of neurotoxin exposure is used, wherein 6-hyrdoxy dopamine is injected into the brain of rats, followed approximately 4 weeks later by a biochemical picture resembling Parkinson's disease (PD). On the side of the brain where the neurotoxin is injected, there is a 90% reduction in the level of a key enzyme, tyrosine hydroxylase (TH), that is a rate-limiting enzyme involved in dopamine production. Dopamine is the neurotransmitter that is deficient in PD. One way that brain TH levels can be restored in conditions such as PD is through gene therapy, wherein the TH gene is given to the individual afflicted with PD. However, with the conventional approach to gene therapy of the brain, there are two serious problems. First, virtually all present-day approaches use viral vectors to carry the gene to brain cells. However, these viral vectors are either highly inflammatory (such as adenovirus or herpes simplex virus) or stably alter the host genome in a random way (retrovirus, adeno-associated virus). These viruses do not enter the brain from blood, because they do not cross the blood-brain barrier (BBB). This creates the second problem with present-day approaches to gene therapy, which is the viral vector is administered to the brain by craniotomy and drilling a hole in the head. However, this only distributes the virus to a tiny region of the brain at the tip of the injection needle. ...

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Section: Discussionsupporting

confidence: 72%

Non-Invasive Gene Therapy of Experimental Parkinson's Disease

Pardridge¹

2003

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“…Moreover, expression of the GTPCH gene is highly dynamic, can be induced in cell types that do not normally express it, and is controlled by a growing number of signal transduction pathways that presumably converge on the GTPCH promoter (5)(6)(7)(8)(9). The genes encoding for human and mouse GTPCH have recently been cloned (10), and their 5Ј-flanking regions have been shown to promote transcription of heterologous reporter genes (11,12). Nonetheless, virtually nothing is known regarding either the cis-acting elements or trans-acting factors that control the expression of GTPCH.…”

mentioning

confidence: 99%

Identification and Characterization of Basal and Cyclic AMP Response Elements in the Promoter of the Rat GTP Cyclohydrolase I Gene

Kapatos

Stegenga

Hirayama

2000

Journal of Biological Chemistry

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5812 base pairs of rat GTP cyclohydrolase I (GTPCH) 5-flanking region were cloned and sequenced, and the transcription start site was determined for the gene in rat liver. Progressive deletion analysis using transient transfection assays of luciferase reporter constructs defined the core promoter as a highly conserved 142-base pair GC-rich sequence upstream from the cap site. DNase I footprint analysis of this region revealed (5 3 3) a Sp1/GC box, a noncanonical cAMP-response element (CRE), a CCAAT-box, and an E-box. Transcription from the core promoter in PC12 but not C6 or Rat2 cells was enhanced by incubation with 8-bromo-cyclic AMP. Mutagenesis showed that both the CRE and CCAAT-box independently contribute to basal and cAMP-dependent activity. The combined CRE and CCAAT-box cassette was also found to enhance basal transcription and confer cAMP sensitivity on a heterologous minimal promoter. The addition of the Sp1/GC box sequence to this minimal promoter construct inhibited basal transcription without affecting the cAMP response. EMSA showed that nuclear proteins from PC12 but not C6 or Rat2 cells bind the CRE as a complex containing activating transcription factor (ATF)-4 and CCAAT enhancer-binding protein ␤, while both PC12 and C6 cell nuclear extracts were recruited by the CCAAT-box as a complex containing nuclear factor Y. Overexpression of ATF-4 in PC12 cells was found to transactivate the GT-PCH promoter response to cAMP. These studies suggest that the elements required for cell type-specific cAMPdependent enhancement of gene transcription are located along the GTPCH core promoter and include the CRE and adjacent CCAAT-box and the proteins ATF-4, CCAAT enhancer-binding protein ␤, and nuclear factor Y.

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“…The only difference between these studies performed with the SV40 or the Gfap promoter was a 10-fold increase in the levels of TH activity seen in liver of animals injected with the SV40-TH construct, which is not seen with the Gfap-TH plasmid (Table II). The stability of the TH enzyme is associated with the availability of the biopterin cofactor, and the expression of the TH enzyme is found in regions of the brain that express GTP cyclohydrolase 1 (GTPCH) (44)(45)(46). The GTPCH is also expressed in peripheral tissues, like liver (47), which supports the increased expression in liver TH activity when this transgene is driven by the SV40 promoter (Table II) (20).…”

Section: Brain Expression Of Therapeutic Genesmentioning

confidence: 78%

Blood–brain Barrier Transport of Non-viral Gene and RNAi Therapeutics

Boado¹

2007

Pharm Res

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The development of gene- and RNA interference (RNAi)-based therapeutics represents a challenge for the drug delivery field. The global brain distribution of DNA genes, as well as the targeting of specific regions of the brain, is even more complicated because conventional delivery systems, i.e. viruses, have poor diffusion in brain when injected in situ and do not cross the blood-brain barrier (BBB), which is only permeable to lipophilic molecules of less than 400 Da. Recent advances in the "Trojan Horse Liposome" (THL) technology applied to the transvascular non-viral gene therapy of brain disorders presents a promising solution to the DNA/RNAi delivery obstacle. The THL is comprised of immunoliposomes carrying either a gene for protein replacement or small hairpin RNA (shRNA) expression plasmids for RNAi effect, respectively. The THL is engineered with known lipids containing polyethyleneglycol (PEG), which stabilizes its structure in vivo in circulation. The tissue target specificity of THL is given by conjugation of approximately 1% of the PEG residues to peptidomimetic monoclonal antibodies (MAb) that bind to specific endogenous receptors (i.e. insulin and transferrin receptors) located on both the BBB and the brain cellular membranes, respectively. These MAbs mediate (a) receptor-mediated transcytosis of the THL complex through the BBB, (b) endocytosis into brain cells and (c) transport to the brain cell nuclear compartment. The present review presents an overview of the THL technology and its current application to gene therapy and RNAi, including experimental models of Parkinson's disease and brain tumors.

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GTP Cyclohydrolase I Gene Expression in the Brains of Male and Female hph‐1 Mice

Cited by 52 publications

References 32 publications

Non-Invasive Gene Therapy of Experimental Parkinson's Disease

Non-Invasive Gene Therapy of Experimental Parkinson's Disease

Identification and Characterization of Basal and Cyclic AMP Response Elements in the Promoter of the Rat GTP Cyclohydrolase I Gene

Blood–brain Barrier Transport of Non-viral Gene and RNAi Therapeutics

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