| Project/Area Number |
15500263
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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 |
Neurochemistry/Neuropharmacology
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| Research Institution | University of Miyazaki (2004)
宮崎医科大学 (2003) |
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Principal Investigator |
KOBAYASHI Hideyuki University of Miyazaki, Faculty of Medicine, Associate Professor, 医学部, 助教授 (40148953)
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| Co-Investigator(Kenkyū-buntansha) |
WADA Akihiko University of Miyazaki, Faculty of Medicine, Professor, 医学部, 教授 (30131949)
YANAGITA Toshihiko University of Miyazaki, Faculty of Medicine, Assistant Professor, 医学部, 助手 (60295227)
YOKOO Hiroki University of Miyazaki, Faculty of Medicine, Assistant Professor, 医学部, 助手 (30332894)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2003: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | voltage-dependent Na+ channel / β-subunit / cell adhesion molecule / cell differentiation / nerve growth factor / regulation of expression / intracellular trafficking / localization / 電位依存性Na+チャネル / 分化 / 強制発現 / GFP / PC12細胞 / MAPキナーゼ |
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| Research Abstract |
Voltage-dependent Na^+ channel β-subunits contain a single extracellular Ig-like domain with structural similarity to the cell adhesion molecules. In this project, we have studied the regulatory mechanisms of expression and intracellular trafficking of the β-subunits as well as their role in cell differentiation.
In cultured bovine adrenal chromaffin cells, insulin and IGF-1 increased cell surface expression of Na^+ channels. Insulin and IGF-1 increased Na^+ channel α-subunit mRNA level but not (β-subunit mRNA level. In rat pheochromocytoma PC 12 cells, neuronal differentiation by nerve growth factor increased β_1-subunit mRNA level but not β_3-subunit mRNA level, indicating that the mechanisms regulating the expression of a-subunit and β-subunits are different.
When HEK293 cells were transfected with GFP tagged β-subunit constructs, β_1-Subunit-GFP was expressed strongly at the cell surface and weakly in endoplasmic reticulum. β_2-Subunit-GFP was expressed predominantly at cell surface, and these cells extended many microvilli. β_3-Subunit-GFP was expressed strongly at cell membrane and at intracellular spherical membrane structure, and these cells also extended microvilli, indicating that the intracellular trafficking and the physiological function of the β-subunits are different. In addition, PC12 cells expressing each subunit tagged with GFP extended neuritis even in the absence of nerve growth factor, and the effects of β_2-GFP or β_3-GFP were stronger than that of β_1-GFP. The neurite extending effects of nerve growth factor were more pronounced in each β-subunit-GFP expressing cells than in the control cells.
These results indicate that β-subunits play a role in the regulation of cell differentiation, and that the intracellular trafficking mechanisms of the β-subunits and their regulatory mechanisms of expression are different.
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