| Project/Area Number |
10672072
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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 |
Biological pharmacy
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| Research Institution | Kyoto Pharmaceutical University |
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Principal Investigator |
SATO Takashi Kyoto Pharmaceutical University, School of Pharmaceutical Sciences, Professor, 薬学部, 教授 (40065917)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | cdramide / sphingomyelinase / mitogen-activated protein kinase / phospholipase AィイD22ィエD2 / arachidonic acid / platelet / スフィンゴ脂質 / ホスホリパーゼC |
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| Research Abstract |
The present study has been undertaken to investigate whether ceramide can regulate phospholipase activation in response to stimuli using cells increased with ceramide by phospholipase activation in response to stimuli using cells increased with ceramide by addition of cell permeable CィイD26ィエD2-ceramide (N-hexanoylsphingosine) or sphingomyelinase treatment. The results obtained are as follows.
1.Activation of cytosolic type "IV" phosholipase AィイD22ィエD2(cPLAィイD22ィエD2) and liberation of arachidonic acid in rabbit platelets in response to low concentration of thrombin, were stimulated by CィイD26ィエD2-ceramide. These effects of ceramide are clarified to be mediated by the mechanism by which ceramide enhances thrombin-stimulated phospholipase C and protein kinase C activation followed by sequential mitogen-activated protein kinase (MARK)-cPLAィイD22ィエD2 activation.
2.Stimulation of platelets with U46619 induced a little liberation of arachidonic acid, whereas it elicited the remarkable liberation
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without activation of cPLAィイD22ィエD2 in platelets with increased ceramide These results suggest that ceramide increased susceptibility of cPLAィイD22ィエD2 to lipid bilayer through modulation of phospholipid organization. This possibility was confirmed by the findings that CaィイD12+ィエD1 -dependent increase in cPLAィイD22ィエD2 proteins in membrane fractions when platelets were stimulated with CaィイD12+ィエD1 inophore or CaィイD12+ィエD1 was added into platelet lysate, was enhanced in the membrane fractions prepared from ceramide-increased platelets or its lysate.
3. We have shown that CィイD26ィエD2-ceramide decreased antigen-induced prostaglandin DィイD22ィエD2 generation in rat basophilic leukemia cells. Therefore, we investigated the effect of ceramide on MAPK, which regulates agonist-stimulated cPLィイD22ィエD2 activity. The results obtained indicate that ceramide inhibited antigen-simulated p42/p44 MARK activation and this inhibition was recovered by treatment with orthovanadate, suggesting a possibility that ceramide stimulated a protein tyrosine phosphatase.
These results indicate a possibility that ceramide generated under stimulation acts as a physiological factor to regulate agonist-stimulated phospholipase activation. Less
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