Gaposchkin Daniel P, Farber Harrison W, Zoeller Raphael A
Department of Physiology and Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, Massachusetts 02118, USA.
Biochim Biophys Acta. 2008 Apr;1781(4):213-9. doi: 10.1016/j.bbalip.2008.01.007. Epub 2008 Feb 20.
We examined the dependence of stimulated arachidonic acid release on plasmalogens using the murine, macrophage cell line 264.7 and two plasmalogen-deficient variants, RAW.12 and RAW.108. All three strains responded to unopsinized zymosan to release arachidonic acid from phospholipid stores. Arachidonic acid release appeared to be dependent on calcium-independent phospholipase A(2) activation (iPLA(2)); bromoenol lactone, a specific inhibitor of calcium-independent iPLA(2), blocked arachidonic acid release with an IC(50) of approximately 2 x 10(-7)M. Propanolol, an inhibitor of phosphatidate phosphatase, and RHC-80267, an inhibitor of diglyceride lipase, had no effect on arachidonic acid release. Arachidonic acid release in the variants displayed similar magnitude, kinetics of response and sensitivity to the inhibitors when compared to the parent strain. Arachidonic acid was released from all major phospholipid head group classes with the exception of sphingomyelin. In wild-type cells, arachidonic acid released from the ethanolamine phospholipids was primarily from the plasmalogen form. However, in the plasmalogen-deficient cells release from the diacyl species, phosphatidylethanolamine, was increased to compensate. Restoration of plasmalogens by supplementation of the growth medium with the bypass compounds sn-1-hexadecylglycerol and sn-1-alkenylglycerol had no effect on arachidonic acid release. In summary, plasmalogen status appears to have no influence on the zymosan A stimulated release of arachidonic acid from the RAW 264.7 cell line.
我们使用小鼠巨噬细胞系264.7以及两个缺乏缩醛磷脂的变体RAW.12和RAW.108，研究了刺激的花生四烯酸释放对缩醛磷脂的依赖性。所有这三种细胞系对未调理的酵母聚糖均有反应，可从磷脂储存中释放花生四烯酸。花生四烯酸的释放似乎依赖于不依赖钙的磷脂酶A2（iPLA2）的激活；溴烯醇内酯是一种不依赖钙的iPLA2的特异性抑制剂，它以约2×10⁻⁷M的半数抑制浓度（IC50）阻断花生四烯酸的释放。丙醇（一种磷脂酸磷酸酶抑制剂）和RHC - 80267（一种甘油二酯脂肪酶抑制剂）对花生四烯酸的释放没有影响。与亲代细胞系相比，变体中的花生四烯酸释放表现出相似的幅度、反应动力学和对抑制剂的敏感性。除鞘磷脂外，花生四烯酸从所有主要的磷脂头部基团类别中释放出来。在野生型细胞中，从乙醇胺磷脂释放的花生四烯酸主要来自缩醛磷脂形式。然而，在缺乏缩醛磷脂的细胞中，来自二酰基种类磷脂酰乙醇胺的释放增加以进行补偿。通过在生长培养基中添加旁路化合物sn - 1 - 十六烷基甘油和sn - 1 - 烯基甘油来恢复缩醛磷脂，对花生四烯酸的释放没有影响。总之，缩醛磷脂状态似乎对酵母聚糖A刺激的RAW 264.7细胞系中花生四烯酸的释放没有影响。
