Exogenously added human group X secreted phospholipase A2 but not the group IB, IIA, and V enzymes efficiently release arachidonic acid from adherent mammalian cells
Exogenously added human group X secreted phospholipase A2 but not the group IB, IIA, and V enzymes efficiently release arachidonic acid from adherent mammalian cells
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DOI：
10.1074/jbc.275.5.3179
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发表时间：
2000-02-04
影响因子：
4.8
通讯作者：
Gelb, MH
中科院分区：
文献类型：
--
作者：
Bezzine, S;Koduri, RS;Gelb, MH
哺乳动物分泌型磷脂酶A（2）（sPLA 2）包括一组至少8种酶，包括最近鉴定的X组sPLA 2。抑制研究表明，sPLA 2抑制剂LY 311727与人类IIA组sPLA 2的结合比与hGX的结合更紧密，并且IIA组sPLA 2的基于吡唑的抑制剂对hGX的活性低得多。确定了囊泡结合的hGX的磷脂头基偏好，hGX与磷脂酰胆碱囊泡紧密结合，这被认为是有效作用于细胞所需的。色氨酸67 hGX对与两性离子囊泡的界面结合做出显著贡献。当外源性加入粘附的哺乳动物细胞时，低至10 ng/ml的hGX释放花生四烯酸用于环氧合酶-2依赖性前列腺素E-2的产生。相比之下，人IIA组、大鼠V组和小鼠IB组sPLA 2在外源性添加到粘附细胞时在释放花生四烯酸方面几乎是无活性的。从生长表面去除细胞增强了所有sPLA 2释放脂肪酸的能力。CHO-K1细胞突变体的研究表明，sPLA 2与糖胺聚糖的结合不是IB、IIA和V组sPLA 2的质膜水解不良的基础。
Mammalian secreted phospholipases A(2) (sPLA2s) comprise a group of at least eight enzymes, including the recently identified group X sPLA2, A bacterial expression system was developed to produce human group X sPLA2 (hGX). Inhibition studies show that the sPLA2 inhibitor LY311727 binds modestly more tightly to human group IIA sPLA2 than to hGX and that a pyrazole-based inhibitor of group IIA sPLA2 is much less active against hGX. The phospholipid head group preference of vesicle-bound hGX was determined, hGX binds tightly to phosphatidylcholine vesicles, which is thought to be required to act efficiently on cells. Tryptophan 67 hGX makes a significant contribution to interfacial binding to zwitterionic vesicles. As little as 10 ng/ml hGX releases arachidonic acid for cyclooxygenase-2-dependent prostaglandin E-2 generation when added exogenously to adherent mammalian cells. In contrast, human group IIA, rat group V, and mouse group IB sPLA2s are virtually inactive at releasing arachidonate when added exogenously to adherent cells. Dislodging cells from the growth surface enhances the ability of all the sPLA2s to release fatty acids. Studies with CHO-K1 cell mutants show that binding of sPLA2s to glycosaminoglycans is not the basis for poor plasma membrane hydrolysis by group IB, IIA, and V sPLA2s.