| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Plasma PAF-acetylhydrolase (PAF-AH) preferentially hydrolyzes phosphatidylcholines with ω-carboxyl and ω-aldehydic short fatty acyl chains at the sn-2 position. Since these phospholipids are generated by non-enzymatic radical mediated oxidation, this LDL-associated enzyme is hypothesized to play a protective role in removal of pro-inflammatory phospholipids generated by oxidation of LDL particles. On the other hand, a loss-of-function mutation (Val279Phe) is found in 4% of Japanese populations and epidemiological studies suggest that this mutation is a risk factor for atherosclerotic diseases related to oxidative stress. In this study, we examined if accumulation of oxidized phosphatidylcholines is caused in the subjects with Val279Phe mutation by ESI-MS/MS analysis. When the LDL was treated with 5μM of Cu^<2+> for 3 h, 16:0-18:2 (+O), 18:0-18:2 (+P), 16:0-18:2 (+2O) and 18:0-18:2 (+2O) were accumulated in the LDL from the subject with this mutation. In addition, 16:0-18:2 (+O), 18:0-18:2 (+O) and 16:0-18:2 (+2O) were detected by incubating the LDL without Cu^<2+> for 16 h. By contrast, these oxidized phospholipids were not detected, when the LDL from the subjects with normal plasma PAF-AH activity was treated with Cu^<2>+. Furthermore, when the LDL from the subjects with normal PAF-AH enzyme activity was treated with DFP, the amounts of these oxidized phosphatidylcholines, which were accumulated in the LDL from the subjects with PAF-AH deficiency, were significantly increased. These results suggest that phosphatidylcholines with hydroxyl and hydroperoxyl long fatty acyl chains are one of the physiological substrates for this enzyme and this enzyme might play a role in degradation of these oxidized phospholipids.
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