2006 Fiscal Year Final Research Report Summary
The function and biological significance of nonselective cation channels expressed in endocine cells.
| Project/Area Number |
17590954
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Endocrinology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKANO Koji The University of Tokyo, Faculty of Medicine, Assistant Professor, 医学部附属病院, 助手 (20236243)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Ion channels / Endocrine cells / Hormone secretion / Pituitary cells / growth hormone / ghrelin / IGF-1 |
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| Research Abstract |
The significance of nonselective cation current in hormone secretion from anterior pituitary cells was investigated. Fusion gene of GH and yellow fluorescent protein was transfected into GH3 cells. Fusion protein was expressed in exocytotic vesicles and was observed by confocal microscope. Exocytotic events were visualized by confocal imaging of the fluorescent fusion protein. Depolarization by high extracellular K stimulated exocytosis. Nitrendipine, a blocker of L-type voltage-gated calcium channel almost abolished high K-induced exocytosis. TRH also stimulated the exocytosis that was attenuated by nitrendipine. Replacing the extracellular sodium by inert cation tetramethylammonium attenuated the TRH-induced exocytosis suggesting the role of nonselective cation current on the exocytotic events.
After the exocytotic events, hormone in the exocytotic vesicles should be refilled by activating the de-novo transcription of hormone. The transcription activation of GH was inventigated in GH3 by luciferase assay. Stimulators of exocytosis also stimulated transctiption activation in these cells. Regulators of hormone secretion such as calcium influx through L-type voltage-gated calcium channels and PKA were also involved in the regulation of GH transcription regulation.
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[Journal Article] Analysis of the mechanisms of intracellular transport and secretion of pituitary hormone, with an insight of subcellular localization of pituitary hormone and its nRNA2006
Author(s)
Matsuno A, Mizutani A, Takekoshi S, Itoh J, Okinaga H, Nishina Y, Takano K, Nagashima T, Osamura RY, Teramoto A.
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Journal Title
Description
「研究成果報告書概要(欧文)」より
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