| Project/Area Number |
06454182
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Pathological medical chemistry
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| Research Institution | Fujita Health University |
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Principal Investigator |
KOBAYASHI Kazuto Fujita Health University, Institute for Comprehensive Medical Science (Neurochemistry), Assistant Professor, 総合医科学研究所(神経化学), 講師 (90211903)
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| Co-Investigator(Kenkyū-buntansha) |
NAGATSU Toshiharu Fujita Health University, Institute for Comprehensive Medical Science, (Neuroche, 総合医科学研究所(神経化学), 教授 (40064802)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1994: ¥6,700,000 (Direct Cost: ¥6,700,000)
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| Keywords | Catecholaminergic Neurons / Tyrosine Hydroxylase / Dopamine beta-Hydroxylase / Phenylethanolamine N-Methyltransferase / Adrenergic Receptors / Immunotoxin-Mediated Cell Targeting / Transgenic Mouse / Gene Targeting |
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| Research Abstract |
(1) Genetic alteration of catecholamine specificity and regulated expression of adrenergic receptor subtypes-Transgenic mice expressing PNMT under the control of the DBH promoter were generated to switch catecholamine specificity. In the targeted tissues innervated by sympathetic neurons of transgenic mice, the number of beta2-AR binding sites was dramatically decreased, and beta1-AR binding sites were regulated in a different fashion among the tissues. Our data indicate that alteration of catecholamine specificity in transgenic mice leads to regulated expression of the beta-AR subtypes in the target tissues. (2) High level expression of dopamine beta-hydroxylase and regulation of catecholamine metabolism-Transgenic mice were generated with multiple copies of a human DBH minigene construct to achieve overexpression of DBH.The transgene products were correctly processed to a glycosylated mature polypeptide. Expression of human DBH in transgenic mice led to marked increase in the enzyme
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activity in various catecholamine-containing tissues, but the steady-state levels of noradrenaline and adrenaline were normally maintained without the acceleration of the catecholamine turnover rate, suggesting some regulatory mechanisms to preserve a constant rate of noradrenaline synthesis in spite of the increased amount of DBH protein. (3) Catecholamine depletion and perinatal lethality in tyrosine hydroxylase-mutant mice-Mice lacking the TH gene generated by gene targeting showed the lethality at a late stage of embryonic development or shortly after birth. The TH mutation resulted in severe depletion of three kinds of catecholamine, but did not affect gross morphological development of the cells that normally produce catecholamines. Analysis of electrocardiograms of surviving mutants showed bradycardia, suggesting an alteration of cardiac funcitons in the homozygous mice. In addition, tranfer of a human TH transgene into the homozygous mice corrected the mutant phenotype, showing recovery of TH activity by expression of the human enzyme. Our results represent that TH is essential for survival of the animals during the late gestational development and after birth. (4) Conditional disruption of specific neuronal types by immunotoxin-mediated cell targeting-We have developed a novel transgenic approach to ablate inducibly selective neurons in the brain with the cytotoxic activity of immunotoxins. Transgenic mice were created that express the human IL-2Ralpha under the control of the DBH promoter. The animals were treated i.c.v. with an immunotoxin anti-Tac (Fv) -PE40, which selectively kills animal cells bearing human IL-2Ralpha. The immunotoxin caused a characteristic behavioral abnormality only in transgenic mice, which was accompanied by a dramatic loss of DBH-containing neurons and a significant decrease in DBH activity and noradrenaline levels. This approach provides a general technique to create animal models of human neurodegenerative disorders by targetin Less
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