Xu F Y, Taylor W A, Hatch G M
Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Canada.
Arch Biochem Biophys. 1998 Jan 15;349(2):341-8. doi: 10.1006/abbi.1997.0460.
The effect of phospholipase A2 treatment on cardiolipin biosynthesis was investigated in intact H9c2 cardiac myoblasts. Treatment of cells with Naja mocambique mocambique phospholipase A2 reduced the pool sizes of phosphatidylcholine and phosphatidylethanolamine compared with controls. The pool sizes of lysophosphatidylcholine and lysophosphatidylethanolamine were elevated, whereas the pool sizes of cardiolipin and other phospholipids were unaffected by phospholipase A2 treatment. Pulse labeling experiments with [1,3-3H]glycerol and pulse-chase labeling experiments with [1,3-3H]glycerol were performed in cells incubated or preincubated in the absence or presence of phospholipase A2. In all experiments, radioactivity incorporated into cardiolipin was reduced in phospholipase A2-treated cells with time compared with controls, indicating attenuated de novo biosynthesis of cardiolipin. The mechanism for the reduction in cardiolipin biosynthesis in phospholipase A2-treated cells was a decrease in the activity of phosphatidic acid:cytidine-5'-triphosphate cytidylyltransferase, the rate-limiting enzyme of cardiolipin biosynthesis, mediated by elevated cellular lysophosphatidylcholine levels. The results suggest that de novo cardiolipin biosynthesis in H9c2 cells may be regulated by the cellular level of lysophosphatidylcholine.
在完整的H9c2心肌成肌细胞中研究了磷脂酶A2处理对心磷脂生物合成的影响。与对照组相比，用莫桑比克眼镜蛇磷脂酶A2处理细胞可降低磷脂酰胆碱和磷脂酰乙醇胺的池大小。溶血磷脂酰胆碱和溶血磷脂酰乙醇胺的池大小升高，而心磷脂和其他磷脂的池大小不受磷脂酶A2处理的影响。在不存在或存在磷脂酶A2的情况下孵育或预孵育的细胞中进行了用[1,3-3H]甘油的脉冲标记实验和用[1,3-3H]甘油的脉冲追踪标记实验。在所有实验中，与对照组相比，磷脂酶A2处理的细胞中掺入心磷脂的放射性随时间减少，表明心磷脂的从头生物合成减弱。磷脂酶A2处理的细胞中心磷脂生物合成减少的机制是由细胞溶血磷脂酰胆碱水平升高介导的磷脂酸：胞苷-5'-三磷酸胞苷转移酶（心磷脂生物合成的限速酶）活性降低。结果表明，H9c2细胞中心磷脂的从头生物合成可能受细胞溶血磷脂酰胆碱水平的调节。
