1996 Fiscal Year Final Research Report Summary
Studies on the coupling mechanism of phosphplioase D and protein kinase C activation.
| Project/Area Number |
07457042
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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 |
Pathological medical chemistry
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| Research Institution | Kobe University |
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Principal Investigator |
NAKAMURA Shun-ichi Kobe University, School of Medicine, Professor, 医学部, 教授 (40155833)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Kimihisa Kobe University, School of Medicine, Research Associate, 医学部, 助手 (50263372)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Siqnal transduction / Protein kinase C / tyrosine kinase / Phospholipase D / G-protein / ARF / RhoA |
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| Research Abstract |
The hydrolysis of phosphatidylcholine by phosphplioase D (PLD) is caused by a wide variety of external signals, and is now thought to generate several lipid messengers or mediators such as diacylglycerol which is essential to protein kinase C (PKC) activation. To date, some of small molecular weight G-proteins and protein phosphorylation may be involved in the activation of PLD,although precise mechanism of the enzyme regulation ramains to be elucidated. In the series of the present research, we have found that phorbolester or diacylglycerol enhanced GTPgammaS-dependent PLD activity in an ATP-Mg^<2+>-dependent manner in streptolysin-O__--permeabilized HL-60 cells. This enhancement was totally inhibited not only by PKC inhibitors but by tyrosine kinase inhibitors suggesting the involvement of protein kinase C and tyrosine kinase.
In a cell-free system, GTPgammaS was essential to PLD activity using rat kidney lysates. We also found that a novel protein factor other than G-protein is necessary for the action of small molecular weight G-proteins (ADP ribosylation factor or RhoA). The factor is a heat-atable protein with a molecular mass of about 36 kDa in a gel filtration analysis. We also found that phosphatidylethanolamine is essential for PLD activation. These results suggest that the mechanism underlying PLD activation is complex and exquisite forming a stringent regulation network with other signaling molecules.
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