| Project/Area Number |
16590165
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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 |
General physiology
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| Research Institution | Shiga University of Medical Science |
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Principal Investigator |
OMATSU Mariko Shiga University of Medical Science, Assistant Professor, 医学部, 助教授 (80161397)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | store-operated Ca^<2+> entry / P2 receptor / ATP / intracellular Ca^<2+> / cytoskeleton / actin / endoplasmic reticulum / brown adipocyte / 容量生カルシウム流入 |
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| Research Abstract |
Stimulation of P2 receptors with micromolar concentration of ATP not only evokes a transient increase in intracellular free Ca^<2+> concentration ([Ca^<2+>]_i), primarily due to release of Ca^<2+> from intracellular stores ; such stimulation also triggers almost complete suppression of thapsigargin-evoked sustained [Ca^<2+>]_i elevation mediated through a store-operated Ca^<2+> entry pathway in rat brown adipocytes. We investigated the role of cytoskeletal actin in the inhibitory effect which extracellular ATP has on store-operated Ca^<2+> entry, using fura-2 fluorescence for continuous measurement of [Ca^<2+>]_i_, and using Alexa fluor 488-phalloidin staining of actin. Disassembly of actin networks by cytochalasin D (1 μM) or latrunculin A (3 μM) prevented the inhibitory effect of ATP (10 μM) on the thapsigargin (100 μM)-evoked store-operated Ca^<2+>entry, without changing the effect of ATP in raising [Ca^<2+>]_i. In normal cells, bath application of ATP induced a transient [Ca^<2+>]_i elevation consisting of a rapid increase (the rising phase) and the subsequent decrease (the declining phase) to a lower steady level despite the continued presence of the agonist. Disruption of actin assemblies did not significantly affect the rising phase, but prevented the declining phase. Cells incubated with 10 μM ATP for 4 min demonstrated marked accumulations of actin filaments at the cell periphery, showing protrusions at the cell surface ; this actin-assembly process is mediated through P2 receptors. In cells treated with cytochalasin D or latrunculin A, extracellular ATP did not induce actin redistribution. These results suggest the actin reorganization plays a role in ATP-induced inhibition of store-operated Ca^<2+> entry in rat brown adipocytes.
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