Kudoh T, Velkoff M A, Wenger D A
Biochim Biophys Acta. 1983 Nov 1;754(1):82-92. doi: 10.1016/0005-2760(83)90084-x.
The metabolism of [stearoyl-1-14C]- and [choline-methyl-14C]sphingomyelin, [stearoyl-1-14C]ceramide-1-phospho-N,N-dimethylethanolamine (demethylsphingomyelin) and [choline-methyl-14C]phosphatidylcholine was measured 1, 3 and 5 days after uptake from the media of cultured skin fibroblasts. This was done to measure the relative contributions of lysosomal sphingomyelinase and plasma membrane phosphocholine transferase on the metabolism of sphingomyelin, a component of all cell membranes. By using cell lines from controls and from patients with Niemann-Pick disease and other lysosomal storage diseases, it was concluded that a significant portion (10-15%) of the observed degradation of sphingomyelin is due to exchange of the phosphocholine moiety producing phosphatidylcholine. Although cell lines from type A and B Niemann-Pick disease have only 0-2% of lysosomal sphingomyelinase activity measured in vitro, three cell lines from type B Niemann-Pick disease could metabolize 54.4% of the labeled sphingomyelin by day 3 while cell lines from type A Niemann-Pick disease could only metabolize 18.5% by day 3. This compares to 86.7% metabolized in control cells by day 3. Cells from one patient with juvenile Niemann-Pick disease and one with type D Niemann-Pick disease metabolized sphingomyelin normally while cells from two other patients with juvenile or type C Niemann-Pick disease could only metabolize 58.2% by day 3. Cells from patients with I-cell disease and 'lactosylceramidosis' also demonstrated decreased metabolism of sphingomyelin (55.1 and 54.9% by day 3, respectively). Cells from the patient with Farber disease accumulated [14C]stearic acid-labeled ceramide produced from [14C]sphingomyelin. Studies with choline-labeled sphingomyelin and phosphatidylcholine demonstrated that phosphocholine exchange takes place in either direction in the cells, and this is normal in Niemann-Pick disease. Studies in cells from patients with all clinical types of sphingomyelinase deficiency have led to new methods for diagnosis and prognosis and to a better understanding of sphingomyelin metabolism.
在从培养的皮肤成纤维细胞培养基中摄取[硬脂酰-1-¹⁴C]-和[胆碱-甲基-¹⁴C]鞘磷脂、[硬脂酰-1-¹⁴C]神经酰胺-1-磷酸-N,N-二甲基乙醇胺（脱甲基鞘磷脂）和[胆碱-甲基-¹⁴C]磷脂酰胆碱1、3和5天后，对它们的代谢情况进行了测定。这样做是为了衡量溶酶体鞘磷脂酶和质膜磷酸胆碱转移酶对鞘磷脂（所有细胞膜的一种成分）代谢的相对贡献。通过使用来自对照以及患有尼曼-匹克病和其他溶酶体贮积病患者的细胞系，得出的结论是，观察到的鞘磷脂降解中有很大一部分（10 - 15%）是由于磷酸胆碱部分的交换产生了磷脂酰胆碱。尽管来自A型和B型尼曼-匹克病的细胞系在体外测得的溶酶体鞘磷脂酶活性仅为0 - 2%，但来自B型尼曼-匹克病的三个细胞系在第3天时可代谢54.4%的标记鞘磷脂而来自A型尼曼-匹克病的细胞系在第3天时仅能代谢18.5%。相比之下，对照细胞在第3天时可代谢86.7%。一名青少年型尼曼-匹克病患者和一名D型尼曼-匹克病患者的细胞正常代谢鞘磷脂，而另外两名青少年型或C型尼曼-匹克病患者的细胞在第3天时仅能代谢58.2%。患有I细胞病和“乳糖基神经酰胺贮积症”患者的细胞也显示出鞘磷脂代谢降低（分别在第3天时为55.1%和54.9%）。患有法布里病患者的细胞积累了由[¹⁴C]鞘磷脂产生的[¹⁴C]硬脂酸标记的神经酰胺。对用胆碱标记的鞘磷脂和磷脂酰胆碱的研究表明，磷酸胆碱在细胞中可双向交换，这在尼曼-匹克病中是正常的。对所有临床类型鞘磷脂酶缺乏症患者细胞的研究带来了新的诊断和预后方法，并增进了对鞘磷脂代谢的理解。
