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T Nagatsu

Publications and source records attributed to T Nagatsu.

At least 91 records · Page 5Linked to original sources
PubMed1998

Prevention of dopaminergic neuron death by adeno-associated virus vector-mediated GDNF gene transfer in rat mesencephalic cells in vitro.

Glial cell line-derived neurotrophic factor (GDNF) is known as a potent neurotrophic factor for dopaminergic neurons. Since adeno-associated virus (AAV) vector is a suitable vehicle for gene transfer into neurons, rat E14 mesencephalic cells were transduced with an AAV vector expressing GDNF. When compared with mock transduction, a larger number of dopaminergic neurons survived in AAV-GDNF-transduced cultures (234% and 325% of controls at 1 and 2 weeks, respectively; P < 0.01). Furthermore, the dopaminergic neurons in the latter cultures grew more prominent neurites than those in the former. These findings suggest that AAV vector-mediated GDNF gene transfer may prevent dopaminergic neuron death, and is therefore a logical approach for the treatment of Parkinson's disease.

Animals↗
PubMed1998

Significant behavioral recovery in Parkinson's disease model by direct intracerebral gene transfer using continuous injection of a plasmid DNA-liposome complex.

As an alternative to virus-mediated gene transfer, we previously demonstrated a simple, safe, and efficient transfer of foreign gene into the central nervous system using continuous injection of a plasmid DNA-cationic liposome complex. To explore whether this approach can be applied to the treatment of certain neurological disorders, we used an experimental model of Parkinson's disease (PD) in the present study. Following continuous injection for 7 days, tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) genes carried by a bovine papilloma virus-based plasmid vector were efficiently introduced into glial cells in the striatum of 6-hydroxydopamine-lesioned rats. Significant recovery in apomorphine-induced rotational behavior of PD models was obtained by transfection of TH gene and this effect continued for up to 5 weeks after injection. Moreover, cotransfection of TH with AADC genes was readily accomplished by this procedure and resulted in a greater and longer-lasting improvement of apomorphine-induced rotational behavior than was achieved by transfection of TH gene alone. We suggest that this approach is a controllable and manageable alternative to other methods of gene therapy for the treatment of PD.

Animals↗
PubMed1998

Phenylethanolamine-N-methyltransferase - immunoreactive nerve terminals afferent to the mouse substantia nigra.

In the substantia nigra pars compacta, many phenylethanolamine-N-methyltransferase immunoreactive (PNMT-ir) terminals as well as serotonin-ir terminals were observed for the first time to be very closely situated to the tyrosine hydroxylase (TH)-ir, aromatic L-amino acid decarboxylase-ir, and GTP cyclohydrolase I (GCH)-ir dopaminergic cells [Nagatsu, I., Arai, R., Sakai, M., Yamawaki, Y., Takeuchi, T., Karasawa, N. and Nagatsu, T., Neurosci. Lett., 224 (1997) 185-188]. Immunohistochemical colocalization of TH with GCH or PNMT in the somata and dendrites of TH-positive neurons in the rostral ventrolateral reticular formation of the medulla oblongata (C1 region, [Hokfelt, T., Fuxe, K., Goldstein, M. and Johansson, O., Brain Res., 66 (1974) 235-251]) was proved by a double-labeling immunofluorescence method with a confocal laser-scanning microscope, indicating that the neurons are adrenergic. These results suggest that dopaminergic neurons in the substantia nigra receive PNMT-ir, adrenergic afferents from the C1 region of the medulla oblongata.

Animals↗
PubMed1998

Autonomic neuropathy in transgenic mice caused by immunotoxin targeting of the peripheral nervous system.

Autonomic neuropathy in several neurodegenerative disorders results from disturbance in physiological functions of different cell types in the central and peripheral nervous systems. For a clearer understanding of the etiology and pathogenesis of the autonomic disorders it is necessary to create animal models in which degeneration of the causative neuronal types can be induced. Immunotoxin-mediated cell targeting (IMCT) is a novel transgenic mouse technology for eliminating selective cell types with the cytotoxic activity of a recombinant immunotoxin anti-Tac(Fv)-PE40. In this study we conditionally disrupted peripheral catecholaminergic cells with IMCT to generate a mouse model developing autonomic failure based on primary defects of the sympathetic nervous system. Transgenic mice expressing human interleukin-2 receptor alpha subunit under the control of the dopamine beta-hydroxylase gene promoter were intravenously treated with a proper dose of anti-Tac(Fv)-PE40. The immunotoxin induced a selective loss of the target cells in peripheral tissues of the transgenic mice and an impairment of catecholamine metabolism in the tissues. Targeting of the peripheral catecholaminergic cells resulted in severe and progressive phenotypic abnormalities mainly characterized by cardiac dysfunction, hypoactivity, and hypothermia, which explain development of autonomic neuropathy. Our IMCT strategy is useful for elucidating the involvement of different neuronal types and their interactions in the development and symptom of autonomic disorders.

Animals↗
PubMed1998

IL-1 beta and TNF-alpha suppress apolipoprotein (apo) E secretion and apo A-I expression in HepG2 cells.

The effect of cytokines on apolipoprotein E (apo E) production and secretion was investigated in a human hepatoma cell line HepG2. Incubation of HepG2 cells with interleukin 1 beta (IL-1 beta) or tumour necrosis factor alpha (TNF-alpha) for 48 h resulted in a significant dose-related decrease of apo E concentration in the culture medium, while intracellular apo E content increased without change in mRNA level. In contrast, IL-1 beta and TNF-alpha decreased both intracellular and medium apo A-I. Elution profiles of cholesterol and apolipoproteins revealed that apo E was present in apo E-rich high density lipoprotein (HDL) fraction and apo A-I was in apo E-rich HDL and small HDL fractions. IL-1 beta and TNF-alpha decreased both apo E and apo A-I in these fractions. The present results suggest that IL-1 beta and TNF-alpha suppress hepatic apo A-I expression and secretion but not expression of apo E, which could contribute to the abnormal lipid metabolism in certain cytokine-mediated inflammatory diseases.

Apolipoprotein A-I↗
PubMed1998

Dopamine beta-hydroxylase: two polymorphisms in linkage disequilibrium at the structural gene DBH associate with biochemical phenotypic variation.

Levels of the enzyme dopamine beta-hydroxylase (DbetaH) in the plasma and cerebrospinal fluid (CSF) are closely related biochemical phenotypes. Both are under strong genetic control. Linkage and association studies suggest the structural gene encoding DbetaH (locus name, DBH) is a major locus influencing plasma activity of DbetaH. This study examined relationships of DBH genotype determined at two polymorphic sites (a previously described GT repeat, referred to as the DBH STR and a single-base substitution at the 3' end of DBH exon 2, named DBH*444 g/a), to CSF levels of DbetaH protein in European-American schizophrenic patients, and to plasma DbetaH activity in European-American patients with mood or anxiety disorders. We also investigated linkage disequilibrium (LD) between the polymorphisms in the pooled samples from those European-American subjects (n=104). Alleles of DBH*444 g/a were associated with differences in mean values of CSF DbetaH levels. Alleles at both polymorphisms were associated with plasma DbetaH activity. Significant LD was observed between respective alleles with similar apparent influence on biochemical phenotype. Thus, allele A3 of the DBH STR was in positive LD with DBH*444a, and both alleles were associated with lower plasma DbetaH activity. DBH STR allele A4 was in positive LD with DBH*444 g, and both alleles were associated with higher plasma DbetaH activity. The results confirm that DBH is a major quantitative trait locus for plasma DbetaH activity, and provide the first direct evidence that DBH also influences CSF DbetaH levels. Both polymorphisms examined in this study appear to be in LD with one or more functional polymorphisms that mediate the influence of allelic variation at DBH on DbetaH biochemical phenotypic variation

Anxiety Disorders↗
PubMed1998

Enzymes related to catecholamine biosynthesis in Tetrahymena pyriformis. Presence of GTP cyclohydrolase I.

We first identified GTP cyclohydrolase I activity (EC 3.5.4.16) in the ciliated protozoa, Tetrahymena pyriformis. The Vmax value of the enzyme in the cellular extract of T. pyriformis was 255 pmol mg-1 protein h-1. Michaelis-Menten kinetics indicated a positive cooperative binding of GTP to the enzyme. The GTP concentration producing half-maximal velocity was 0.8 mM. By high-performance liquid chromatography (HPLC) with fluorescence detection, a major peak corresponding to D-monapterin (2-amino-4-hydroxy-6-[(1'R,2'R)-1',2',3'-trihydroxypropyl]pteridin e, D-threo-neopterin) and minor peaks of D-erythro-neopterin and L-erythro-biopterin were found to be present in the cellular extract of Tetrahymena. Thus, it is strongly suggested that Tetrahymena converts GTP into unconjugated pteridine derivatives. In this study, dopamine was detected as the major catecholamine, while neither epinephrine nor norepinephrine was identified. Indeed, this protozoa was shown to possess the activity of a dopamine synthesizing enzyme, aromatic L-amino acid decarboxylase. On the other hand, activities of tyrosine hydroxylase or tyrosinase which converts tyrosine into dopa, the substrate of aromatic L-amino acid decarboxylase, could not be detected in this protozoa. Furthermore, neither dopamine beta-hydroxylase activity nor phenylethanolamine N-methyltransferase activity could be identified by the HPLC methods.

Amino Acid Sequence↗
PubMed1998

Cotransduction of tyrosine hydroxylase and aromatic L-amino acid decarboxylase genes into cultured striatal cells using adeno-associated virus vectors.

OBJECTIVE: To examine whether tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) genes can be cotransduced into the same target striatal cells using adeno-associated virus (AAV) vectors, and to determine whether the cotransduction would result in better biochemical change than the TH gene alone. METHODS: TH and AADC genes were cotransduced into cultured striatal cells with separate AAV vectors. Expressions of TH and AADC were detected by immunocytochemistry; intracellular catecholamine levels were assayed by high-performance liquid chromatography (HPLC). RESULTS: TH and AADC genes were efficiently cotransduced into the striatal cells. Specifically, the coexpression of TH and AADC resulted in more effective dopamine production compared with the TH gene alone. CONCLUSION: Using AAV vectors, coexpression of TH and AADC in the striatal cells might be a useful approach to gene therapy for Parkinson's disease.

Animals↗
PubMed1998

[Molecular biology of hereditary dystonia].

The causative genes of hereditary dystonia (hereditary progressive dystonia, HPD; dopa-responsive dystonia, DRD) were discovered in 1994-1995. HPD/DRD is caused by the deficiency of dopamine to less than 20% of the normal level in the nigro-striatum of the brain owing to the mutations of the dopamine synthesizing enzymes. Autosomal dominant dystonia (Segawa's disease) was found to be caused by mutations of GTP cyclohydrolase I which synthesizes tetrahydrobiopterin, the cofactor of tyrosine hydroxylase, by Ichinose et al. (Nature Genetics, 1994) in Japan. Autosomal recessive dystonia was reported to be caused by mutations of tyrosine hydroxylase by Lüdecke et al. (Human Genetics, 1995) in Germany. Hereditary dystonia, especially autosomal dominant Segawa's disease can be completely controlled by L-dopa administration. Measurement of the activity of GTP cyclohydrolase I in mononuclear blood cells is useful for the diagnosis of Segawa's disease.

Amino Acid Sequence↗
PubMed1998

[Structure and function of a novel ErbB ligand, NTAK].

A novel member of the epidermal growth factor (EGF) family, the neural and thymus-derived activator for ErbB kinase (NTAK) has been cloned from the cDNA library of a rat pheochromocytoma cell line, PC12 cells and human neuroblastoma cell line, SK-N-SH cells. Four alternative spliced isoforms from rat cDNA have been detected by the methods of RT-PCR. The rat NTAK alpha 2a isoform exhibits 94% identity in its sequence with the human NTAK alpha isoform. Three characteristic Ig-like, EGF-like and hydrophobic domains have been identified in rat and human NTAK molecules. Recombinant NTAK, the soluble 46 kDa form, binds directly to ErbB3 and ErbB4, but not ErbB1 and B2. NTAK, however, transactivates with heterodimer such as ErbB1/B3, B1/B4, B2/B3, B2/B4, and B3/B4. NTAK stimulates the differentiation of MDA-MB-453 cells, derived from blast carcinoma. NTAK competitively inhibits the binding of [125I] NRG-1 to these cells. Thus, NTAK is a new member of the EGF family displaying NRG-1 properties.

Animals↗
PubMed1997

Cloning and structural organization of the gene encoding the mouse glial cell line-derived neurotrophic factor, GDNF.

cDNA for glial cell line-derived neurotrophic factor (GDNF) was cloned from mouse neonatal brain by the method of 5'-rapid amplification of cDNA end (5'-RACE), and the sequence of it's 5'-untranslated region (5'-UTR) was determined. The mouse GDNF gene was then isolated from a genomic library and analyzed for its nucleotide sequence. In vitro translation analysis indicated that the second ATG codon in an open reading frame is the translation start point. Structural analysis of the isolated clones showed that the GDNF gene was separated into three exons and the actual translation start point was present in the second exon. RNA blot hybridization analysis indicated that the GDNF mRNA is approximately 4.5 kb long. The transcriptional start site in the GDNF gene was determined and a typical TATA box sequence was found in the promoter region. On the other hand, the gene expression of GDNF in C6 glioma cells was transiently induced by treatment with phorbol myristate acetate (PMA), but not by forskolin.

Amino Acid Sequence↗
PubMed1997

Effect of lipopolysaccharide on the gene expression of the enzymes involved in tetrahydrobiopterin de novo biosynthesis in murine neuroblastoma cell line N1E-115.

The amounts of messenger RNA for three enzymes, namely guanosine triphosphate (GTP) cyclohydrolase 1,6-pyruvoyltetrahydropterin synthase, and sepiapterin reductase, all of which are involved in the de novo biosynthesis of (6R)-L-erythrodihydroxypropyl-2-amino-4-hydroxy-5,6,7,8-tetrahydro pteridine (BH4) from GTP, were measured quantitatively in murine neuroblastoma cell line N1E-115 by the competitive polymerase chain reaction (PCR) technique after reverse transcription using a heterologous DNA fragment as an internal standard. Twenty-four hour activation of this cell line with 1 microg/ml lipopolysaccharide resulted in statistically significant increases in the amounts of the messages of all three enzymes. Our data suggest that lipopolysaccharide can activate the intrinsic pathway resulting in the enhanced gene expression of these three enzymes in neuron-derived cells such as N1E-115.

Alcohol Oxidoreductases↗
PubMed1997

Migration activity of microglia and macrophages into rat brain.

We examined the entry of intra-arterially injected microglia and macrophages into the brain using a rat muscle graft model to compare their respective abilities to invade the brain parenchyma. Isolated microglia without any activation treatment entered into the brain with or without the muscle graft, while macrophages activated by phorbol 12-myristate-13-acetate (PMA) entered the brain only in the presence of the muscle graft. These results suggest that microglia have a higher affinity for the brain than macrophages.

Animals↗
PubMed1997

Expression of mRNAs for neuropeptide receptors and beta-adrenergic receptors in human osteoblasts and human osteogenic sarcoma cells.

In human periosteum-derived osteoblastic cells (SaM-1) and human osteosarcoma-derived cells (SaOS-2, HOS, MG-63), the mRNA expressions of calcitonin gene-related peptide receptor (CGRP-R), substance P receptor (SP-R), neuropeptide Y receptor (NPY-R), beta-adrenergic receptors (beta1-R, beta2-R, beta3-R), vasoactive intestinal polypeptide type 1 and type 2 receptors (VIP-1R, VIP-2R) and pituitary adenylate cyclase activating polypeptide receptor (PACAP-R) were examined by reverse transcription-polymerase chain reaction (RT-PCR). According to the magnitude of the mRNA expression of alkaline phosphatase (ALP), the relative state of commitment of these osteoblastic cell lines to the osteoblast lineage was SaM-1 > SaOS-2 > HOS > MG-63. CGRP-R, NPY-R, VIP-1R and beta2-R, but not SP-R, VIP-2R, PACAP-R, beta1-R and beta3-R, were expressed in osteoblasts as well as osteosarcoma cells. Expression of these receptors seems to be a common feature in osteoblastic cells, but the magnitude of expression was not dependent upon the relative state of commitment of the osteoblastic cells to the osteoblast lineage. In addition, VIP mRNA was not expressed in osteoblastic cells, suggesting the absence of an autocrine system of VIP in osteoblasts. These observations suggest that these neuropeptides and norepinephrine are involved in local regulation of human bone metabolism.

Adult↗
PubMed1997

Enhancement or induction of neurite formation by a protein tyrosine phosphatase inhibitor, 3,4-dephostatin, in growth factor-treated PC12h cells.

We studied the effect of the 3,4-dihydroxy analogue of dephostatin (3,4-dephostatin), an inhibitor of protein-tyrosine phosphatase (PTPase), on the differentiation of rat pheochromocytoma PC12 cells. 3,4-Dephostatin accelerated NGF-induced neurite formation in PC12h cells, a subline of PC12 cells, whereas the inhibitor alone did not induce neurite formation. It sustained the NGF-induced tyrosine phosphorylation of several proteins, most prominently that of mitogen-activated protein (MAP) kinase. EGF alone did not induce differentiation in PC12h cells, but it induced neurite formation in the presence of 3,4-dephostatin. The inhibitor also prolonged EGF-induced tyrosine phosphorylation and activation of MAP kinase. An inactive analogue of dephostatin, 2'-O-methyl-dephostatin showed no effect on either neurite formation or MAP kinase tyrosine phosphorylation in NGF or EGF-treated PC12h cells. Thus, we demonstrated that the PTPase inhibitor could enhance growth factor-induced differentiation in PC12 cells possibly by sustaining the MAP kinase activity.

Animals↗