脂多糖增加小鼠巨噬细胞多磷酸肌醇脂代谢转换

Lipopolysaccharide Enhances Polyphosphoinositide Turnover ofMouse Peritoneal Macrophages*

多磷酸肌醇脂（这里指ＰＩＰ和ＰＩＰ２）的代谢在细胞信息传递和膜运转中起着重要的作用．脂多糖（ｌｉｐｏｐｏｌｙｓａｃｃｈａｒｉｄｅ，ＬＰＳ）于激活小鼠腹腔巨噬细胞（Ｍφ）初期（０．５～１ｈ）和后期（１６ｈ）明显增加来自［γ－３２Ｐ］ＡＴＰ的３２Ｐ参入Ｍφ的ＰＩＰ和ＰＩＰ２，３２Ｐ参入ＰＩＰ２的显著性大于ＰＩＰ．ＬＰＳ的这种作用在其激活Ｍφ的初期不受酪氨酸蛋白激酶抑制剂ｇｅｎｉｓｔｅｉｎ、蛋白激酶Ａ激动剂（ｆｏｒｓｋｏｌｉｎ）及百日咳毒素的影响；但佛波酯（ＰＭＡ）长时间预处理的Ｍφ（其ＰＫＣ活性被耗竭）再受ＬＰＳ刺激，［３２Ｐ］ＰＩＰ２水平较ＬＰＳ刺激未受ＰＭＡ预处理的Ｍφ明显降低．结果表明，ＬＰＳ于激活Ｍφ的初期和后期更显著增加ＰＩ４Ｐ－５激酶的活性，导致ＰＩＰ２合成增加，ＰＩＰ２合成的增加可能与Ｍφ激活时不同时期所表达的功能相关．

The metabolism of polyphosphoinositide,phosphatidylinositol4phosphate(PIP) and phosphatidylinositol4,5bisphosphate(PIP 2),plays an important role in transmembrane signal transduction and cellular membrane traffic.In the experiments 1 μg/ml of lipopolysaccharide(LPS)significantly enhanced [32P] from [γ32P] ATP incorporation into PIP and PIP 2 of mouse peritoneal macrophages (Mφ) when they were treated with LPS for 05 h,1 h,16 h,and then pulsed for 05 h or 1 h.The increment of 32P incorporation into PIP 2(16-30 fold) appeared slightly higher than that of PIP(14-25 fold).The same results of 32P incorporation into PIP 2 and PIP of Mφ exposed to LPS for 1 h can also be observed when [32P]Pi was substituted for [γ32P] ATP in pulsing the Mφ.LPSinduced increases in PIP and PIP 2 turnovers of Mφs were not influenced by genistein(tyrosine protein kinase inhibitor),forskolin(protein kinase A activator) and pertussis toxin.The Mφ when pretreated with PMA for 16 h and then stimulated with LPS showed lower level of [32P] PIP 2 than that of treatment with LPS alone.These results indicate that LPS might enhance more significantly the activity of phosphatidylinositol4phosphate 5 kinase,and resulted in the increase in PIP 2 biosynthesis of Mφs.This increase suggests that PIP 2 biosynthesis could be associated with the changes of functional states of Mφs induced by LPS at various stages.