Phosphatidylinositol-3,5-bisphosphate is a potent and selective inhibitor of acid sphingomyelinase
Phosphatidylinositol-3,5-bisphosphate is a potent and selective inhibitor of acid sphingomyelinase
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DOI：
10.1515/bc.2003.144
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发表时间：
2003-09-01
影响因子：
3.7
通讯作者：
Sandhoff, K
中科院分区：
文献类型：
--
作者：
Kölzer, M;Arenz, C;Sandhoff, K
酸性鞘磷脂酶（ASMase，EC 3.1.4.12）催化鞘磷脂的溶酶体降解为磷酸胆碱和神经酰胺。酸性鞘磷脂酶活性的遗传缺陷导致各种临床形式的尼曼匹克病，其特征在于鞘磷脂的大量溶酶体蓄积。酸性鞘磷脂酶和膜相关中性鞘磷脂酶对鞘磷脂的水解在调节增殖、细胞凋亡和分化的细胞信号系统中也发挥着重要作用。在这里，我们提出了一种有效的和选择性的新型ASMase抑制剂，L-α-磷脂酰-D-肌醇-3，5-二磷酸（PtdIns 3，5 P（2）），一种在哺乳动物，植物和酵母细胞中检测到的天然物质。用放射性标记的鞘磷脂作为底物和从昆虫细胞纯化的重组人ASMase，在胶束测定系统中测定，新ASMase抑制剂PtdIns 3，5 P（2）的抑制常数Ki为0.53 μ M。即使在浓度高达50 μ M时，PtdIns 3，5 P（2）既不降低质膜相关的镁依赖性中性鞘磷脂酶活性，也不是溶酶体水解酶β-己糖胺酶A和酸性神经酰胺酶的抑制剂。其他测试的磷酸肌醇对酸性鞘磷脂酶没有影响或影响弱得多。不同的肌醇二磷酸进行了研究，以阐明ASMase抑制的结构反应性关系。我们的研究提供了一个深入了解所需的结构特征选择性，有效抑制酸性鞘磷脂酶，也可以作为起点，为不同的应用优化的新的有效ASMase抑制剂的发展。
Acid sphingomyelinase (ASMase, EC 3.1.4.12) catalyzes the lysosomal degradation of sphingomyelin to phosphorylcholine and ceramide. Inherited deficiencies of acid sphingomyelinase activity result in various clinical forms of NiemannPick disease, which are characterised by massive lysosomal accumulation of sphingomyelin. Sphingomyelin hydrolysis by both, acid sphingomyelinase and membraneassociated neutral sphingomyelinase, plays also an important role in cellular signaling systems regulating proliferation, apoptosis and differentiation. Here, we present a potent and selective novel inhibitor of ASMase, L-alpha-phosphatidyl-D-myo-inositol-3,5-bisphosphate (PtdIns3,5P(2)), a naturally occurring substance detected in mammalian, plant and yeast cells. The inhibition constant K-i for the new ASMase inhibitor PtdIns3,5P(2) is 0.53 muM as determined in a micellar assay system with radiolabeled sphingomyelin as substrate and recombinant human ASMase purified from insect cells. Even at concentrations of up to 50 muM, PtdIns3,5P(2) neither decreased plasma membrane associated, magnesiumdependent neutral sphingomyelinase activity, nor was it an inhibitor of the lysosomal hydrolases beta-hexosaminidase A and acid ceramidase. Other phosphoinositides tested had no or a much weaker effect on acid sphingomyelinase. Different inositolbisphosphates were studied to elucidate structureactivity relationships for ASMase inhibition. Our investigations provide an insight into the structural features required for selective, efficient inhibition of acid sphingomyelinase and may also be used as starting point for the development of new potent ASMase inhibitors optimised for diverse applications.