Hinkovska-Galcheva V T, Boxer L A, Mansfield P J, Harsh D, Blackwood A, Shayman J A
Department of Pediatrics, Division of Hematology/Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA.
J Biol Chem. 1998 Dec 11;273(50):33203-9. doi: 10.1074/jbc.273.50.33203.
Ceramide, a product of agonist-stimulated sphingomyelinase activation, is known to be generated during the phagocytosis of antibody-coated erythrocytes by polymorphonuclear leukocytes. Agonist-stimulated formation of ceramide-1-phosphate is now shown to occur in 32PO4-labeled neutrophils. Ceramide-1-phosphate is formed by a calcium-dependent ceramide kinase, found predominately in the neutrophil plasma membrane. The neutrophil kinase is specific for ceramide because, in contrast to the bacterial diglyceride kinase, ceramide is not phosphorylated under conditions specific for diglyceride phosphorylation. Conversely, 1,2-diacylglycerol does not serve as substrate for the neutrophil ceramide kinase. Ceramide kinase activation occurs in a time-dependent fashion, reaching peak activity 10 min after formyl peptide stimulation and challenge with antibody-coated erythrocytes. The lipid kinase activity is optimal at pH 6.8. Because the formation of the phagolysosome is a critical event in phagocytosis, the effect of ceramide-1-phosphate in promoting the fusion of liposomes was determined. Both the addition of increasing concentrations of sphingomyelinase D and ceramide-1-phosphate promoted liposomal fusion. In summary, ceramide-1-phosphate is formed during phagocytosis through activation of ceramide kinase. Ceramide-1-phosphate may promote phagolysosome formation.
神经酰胺是激动剂刺激的鞘磷脂酶激活的产物，已知在多形核白细胞吞噬抗体包被的红细胞过程中产生。现在表明，在32PO4标记的中性粒细胞中发生激动剂刺激的1-磷酸神经酰胺的形成。1-磷酸神经酰胺由主要存在于中性粒细胞膜中的钙依赖性神经酰胺激酶形成。中性粒细胞激酶对神经酰胺具有特异性，因为与细菌甘油二酯激酶不同，在甘油二酯磷酸化的特定条件下神经酰胺不会被磷酸化。相反，1,2-二酰基甘油不是中性粒细胞神经酰胺激酶的底物。神经酰胺激酶的激活以时间依赖性方式发生，在甲酰肽刺激和用抗体包被的红细胞刺激后10分钟达到峰值活性。脂质激酶活性在pH 6.8时最佳。由于吞噬溶酶体的形成是吞噬作用中的关键事件，因此确定了1-磷酸神经酰胺在促进脂质体融合中的作用。增加浓度的鞘磷脂酶D和1-磷酸神经酰胺的添加均促进脂质体融合。总之，1-磷酸神经酰胺在吞噬过程中通过神经酰胺激酶的激活而形成。1-磷酸神经酰胺可能促进吞噬溶酶体的形成。
