2003 Fiscal Year Final Research Report Summary
A study on the Intracellular dynamics of insulin granules using a phogrin-GFP fused protein
| Project/Area Number |
13470006
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General anatomy (including Histology/Embryology)
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| Research Institution | Fujita Health University |
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Principal Investigator |
SENDA Takao Fujita Health University, School of Medicin, Professor, 医学部, 教授 (10187875)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Yoshimi Fujita Health University, School of Medicine, Research Associate, 医学部, 助手 (40288494)
HIDA Takehiko Fujita Health University, School of Medicine, Associate Professor, 医学部, 助教授 (20097736)
NIKI Ichiro Oita University, School of Medicine, Professor, 医学部, 教授 (10262908)
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| Project Period (FY) |
2001 – 2003
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| Keywords | insulin secretion / MIN6 cells / pancreatic B cells / phogrin / glucose / calmodulin / apoptosis / caveolin-1 |
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| Research Abstract |
1.We constructed an expression vector in which phogrin is bound to the C-terminus of GFP. Using the vector, we successfully expressed. GFP-phogxin in MIN6 cells.
2.We got several new findings concerning regulation mechanisms of the insulin granule traffic.
(1)Glucose accelerated the insulin granule traffic in MIN6 cells. The calmodulin-inhibitor W-7 inhibited the glucose-induced acceleration of the granule traffic, and myosin light chain kinase inhibited the glucose-induced acceleration of the granule traffic.
(2)The blockers to Ca^<2+> channels (nifedipine and nitrendipine) did not inhibit the glucose-induced acceleration of the granule traffic.
(3)The K_<ATP>-opener (diazoxide) did not inhibit the glucose-induced acceleration of the granule traffic.
(4)The glucose stimulation increased phosphatized myosin light chain in MIN6 cells.
3.We investigated the mechanism of B cell loss in transgenic mice with elevated levels of B cell calmodulin.
(1)The transgenic mice experienced a sudden rise in blood glucose levels, which was associated with developed of severe hypoinsulinemia and loss of B cells from the islets.
(2)Ultrastructural analysis revealed that compromised granule formation and apoptotic changes in the transgenic B cells preceded the onset of hyperglycemia.
(3)Intraperitoneal injection of tolbutamide, an antidiabetic sulfonylurea, decreased blood glucose levels but increased the number of apoptotic B cells.
(4)Injection of the mice with N^ω-nitro-L-arginine methyl ester, which inhibits nitric oxide synthase activity, prevented hyperglycemia and lessened the changes in number and size of B cells.
4.We found that caveolin-1 was expressed in MIN6 cells, and colocalized with γ-tubulin in microtubule-organizing center. The signal of caveolin-1 decreased after glucose stimulation.
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